ISSN 1348-8236

USE2008
The 29th Symposiumon
ULTRASONICELECTRONICS
Nov.11-13, 2008 / Sendai╙29࿁⿥㖸ᵄ䉣䊧䉪䊃䊨䊆䉪䉴䈱ၮ␆䈫ᔕ↪䈮㑐䈜䉎䉲䊮䊘䉳䉡䊛⻠Ṷ⺰ᢥ㓸ᐔᚑ䋲䋰ᐕ䋱䋱᦬䋱䋱ᣣ䌾䋱䋳ᣣ ઄บ

主催：超音波シンポジウム運営委員会
共催：応用物理学会
協賛：映像情報メディア学会, 海洋音響学会, 精密工学会, 超音波工業会
電気学会, 電子情報通信学会, 日本音響学会, 日本化学会
日本学術振興会弾性波素子技術第150委員会, 日本機械学会
日本金属学会, 日本生体医工学会, 日本超音波医学会
日本非破壊検査協会, 日本物理学会, 日本分光学会
日本分析化学会, 日本分析機器工業会, IEEE UFFC Society Japan
ChapterProgram of

USE2008
The 29th Symposiumon
ULTRASONICELECTRONICS

Nov.11-13, 2008
Sendai, Japan
URL: http://www.use-jp.org

第２９回 超音波エレクトロニクスの基礎と応用に関するシンポジウム プログラム†講演者*奨励賞応募講演【 】付の題目は論文委員による和訳
第 1 日：11 月 11 日(火)09:00 受付開始
09:50 開会式
10:00-10:45 超音波物性・材料・フォノン物理
1J1-1*
1J1-2
1J1-3*

座長：山中一司 (東北大)超音波共鳴法を用いた金属薄膜の弾性定数の高速回復現象に関する研究
中島丈雄† 中村暢伴 荻博次 平尾雅彦 西山雅祥 （大阪大）
光音響分光法による CdSe 量子ドットを吸着したナノ結晶 Si の熱拡散率評価
小鹿倉淳† 加藤侑志 沈青 豊田太郎 （電通大）
水熱合成法による KNbO3 エピタキシャル膜の作製と特性評価
石河睦生† 宇津木覚 藤澤隆志 安井伸太郎 山田智明 黒澤実 森田剛１ 舟窪浩 (東工大 １東大)1
3
5

10:45-10:50 休憩
10:50-11:50 光－超音波エレクトロニクス / 水中音響
1J3-1*
1J3-2*
1J9-1
1J9-2*

座長：土屋健伸 (神奈川大)FBG を用いたファブリ・ペロー干渉計による振動センシングの検討
和田篤† 杣友宏行 田中哲 高橋信明 (防衛大)
ラム波を用いた高効率な光モード変換器
齋藤光希† 中川恭彦 垣尾省司 (山梨大）
タイムリバーサルによる陰影領域中の物体の探知
鶴ヶ谷芳昭† 菊池年晃１ 水谷孝一２ (NEC １防衛大 ２筑波大)
アプラナートフレネル音響レンズの設計
佐藤裕治† 水谷孝一 若槻尚斗 中村敏明１ (筑波大 １防衛大)

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11:50-13:00 昼食
13:00-14:00 測定技術
1J2a-1*
1J2a-21J2a-3*1J2a-4

座長：大野正弘 (千葉工大)

LFB 超音波材料解析システムによる漏洩弾性表面波伝搬特性の測定モデル
大津賢治† 荒川元孝 櫛引淳一 (東北大)光熱分光法と表面光起電力法による GaAs/AlAs-MQW の電子遷移過程の研究
王萍† 境健太郎 福山敦彦 碇哲雄 （宮大）半導体ナノピラーにおける振動モードのピコ秒音響法による観測
佐久間洋宇† 友田基信 松田理 福井孝志 富岡克広 Oliver B. Wright (北大)
水平すべり波（ＳＨ）波の表面励振
尾上守夫† (東大)

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14:00-16:00 ポスターセッション
1P1-8

矩形断面を持つナノワイヤー超格子に生じる振動モード

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水野誠司† 中村祐史 （北大）

1P1-9
1P1-10
1P1-11*

1P1-12
1P1-13粒子配向型(Bi1/2K 1/2)TiO3-BaTiO3 セラミックスの電気的諸特性
根本正博† 晝間裕二 永田肇 竹中正 (東理大)【離散電極を有する圧電体メンブレン内のラム波の精密解析】
Yung Yu Chen† (Tatung Univ.)【大気圧プラズマ処理の超音波バンプボンディングにおよぼす影響】
Jung-Lae Jo† Ja-Myeong Koo Jong-Bum Lee Seung-Boo Jung Jeong-Hoon Moon１(Sungkyunkwan Univ. １Suwon Sci. Coll.)【フレキシブル電極パターンのガラス基板上への超音波ボンディングと諸条件の影響】
Jong-Bum Lee† Jong-Gun Lee Jung-Lae Jo Ja-Myeong Koo Seung-Boo Jung (Sungkyunkwan Univ.)
球回転式粘度計による界面活性剤水溶液のレオロジー測定
細田真妃子† 小川英生 野村浩康 酒井啓司１ (東京電機大 １東大)

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1P1-14*
1P1-15*
1P1-16*
1P1-17*
1P1-18*
1P2a-1
1P2a-2
1P2a-3
1P2a-4
1P2a-5
1P2a-6*
1P2a-7
1P2a-8*
1P2a-9
1P2a-10
1P2a-11*
1P2a-12*
1P2a-13
1P2a-14*
1P2a-15*
1P2a-16*
1P3-1
1P3-2*
1P3-3*
1P3-4*
1P3-5
1P3-6
1P3-7*
1P3-8(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 三成分系の相関系と電気的諸特性
晝間裕二† 永田肇 竹中正 （東理大）
LiNbO3 の弾性・圧電定数計測と群論による解析
林勇気† 垂水竜一 平尾雅彦 (大阪大)QCM-D 法によるポリスチレンフィルムの粘弾性評価
白井愛子† 浅野洋平 前林正弘１ 香田忍 (名大 １名城大)Brillouin 散乱法による圧電半導体の電気機械結合係数の評価
吉田泰祐† 柳谷隆彦１ 松川真美 (同志社大 １名工大)KNbO3 系強誘電体セラミックスのシェアモード圧電特性疋田康平† 晝間裕二 永田肇 竹中正 (東理大)
超音波マイクロスペクトロスコピー技術による合成石英ガラスの評価
荒川元孝† 島村秀樹 櫛引淳一 (東北大)
レーザ熱波プローブによる高分子透明膜の熱拡散率の推定
得永嘉昭 小林弘幸† 會澤康治 (金工大)
電磁超音波共鳴法による熱時効 Fe-Cu 合金の Cu 析出挙動評価
鎌田康寛† 千種成彦 大谷俊博１ 菊池弘昭 小林悟 (岩手大 １湘南工科大)
非発光遷移検出によるポリジへキシルシランの光分解性評価
福山敦彦† 黒木貴裕 境健太郎 岩本朋久 古川昌司１ 碇哲雄 (宮崎大 １九工大)
ポリ尿素可変線集束トランスデューサの周波数特性
青柳貴洋† 中澤麻梨江 中村健太郎 (東工大)
光学的方法を用いた段付き平板を伝搬する Lamb 波の測定工藤良太† 今野和彦 (秋田大)光干渉計を用いた水中超音波音圧計測における音響光学効果の評価
松田洋一† 吉岡正裕 菊池恒男 (産総研)【水中における水晶型天秤の異常周波数ジャンプ】
Sunhee Choi Mikyung Lim† Young.H. Kim (Korea Sci. Acad.)
マイクロ LFB 超音波デバイスの開発
櫛引淳一 大橋雄二 荒川元孝 田中智也 吉田翔† (東北大)
少量液体試料の非線形パラメータ B/A の自動測定斎藤繁実† 金正鎬１ (東海大 １ジーダブリュー)
非同期型音響波プローブで構成するセンシンググリッドによる気温計測
片野洋介† 若槻尚斗 水谷孝一 (筑波大)
超音波による材料内部および表面の温度分布計測
高橋学† 井原郁夫 (長岡技科大)音響遅延線による湿度計測
昆昭彦† 若槻尚斗 水谷孝一 (筑波大)
フーリエ変換スペクトロメータを用いる円管内の流速測定
泉智之† 若槻尚斗 水谷孝一 (筑波大)反射を用いる音響波プローブによる垂直温度分布計測
吉齋藤育† 水谷孝一 若槻尚斗 川辺聡 (筑波大)【超音波を用いた粘土の先行圧密応力の決定】
Hyung-Koo Yoon† Joon Han Kim Young-Uk Kim１ Jong-Sub Lee (Korea Univ. １Myongji Univ.)
光音響顕微鏡による複合溶接欠陥の非破壊評価
白石大二郎† 遠藤春男 星宮務 (東北学院大)アモルファス Si-Ge-Au 薄膜の光音響スペクトルと熱電特性の相関
滝口裕章† 阿部誠 岡本庸一 宮崎尚 守本純 (防衛大)キャピラリー流路中の光熱変換信号の検出と解析
平島諭† 片江等 原田明 (九大)
固体と気体のブリュアン散乱のミリ秒観察
南康夫† 酒井啓司 (東大生研)
異なるクラッドモード次数を用いた長周期光ファイバグレーティング振動センサの特性杣友宏行† 和田篤 田中哲 高橋信明 (防衛大)
波長多重階層化光ラベルの音響光学導波路回路による認識
後藤信夫† 宮崎保光１ (徳島大 １愛知工大)
弾性表面波を用いたタンデム音響光学周波数シフタの高効率化
新海進† 垣尾省司 川恭彦 原武文１ 伊藤弘昌１ (山梨大 １東北大)弾性表面波を用いた広帯域可視光変調素子
垣尾省司† 新海進 川手寛之 中川恭彦 (山梨大)

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1P3-9*1P4-1*
1P4-2
1P4-3*
1P4-4
1P4-5*
1P4-6
1P4-7
1P4-8
1P4-9
1P4-10*
1P4-11
1P9-6
1P9-7
1P9-8

1P9-9
1P9-10
1P9-11*
1P5-1*
1P5-2*
1P5-3*
1P5-4*
1P5-5
1P5-6*
1P5-7
1P5-8*
1P5-9*
1P5-10*
1P5-11

LiTaO3 および LiNbO3 基板上へのコンタクトエピタキシーによる磁気光学薄膜の形成
田代博之† 野毛悟１ 宇野武彦 (神奈川工大 １沼津高専)
ラム波型弾性波素子基板の伝搬特性
吉田斉師† 中川恭彦 垣尾省司 (山梨大)
機械的インピーダンス不整合系における空間伝達特性計算の行列定式化
大木道生† (防衛大)【指数関数状テーパーをつけた圧電セラミックトランスデューサの解析】
Jungsoon Kim1† Moojoon Kim１ Kanglyeol Ha１ (Tongmyong Univ. １Pukyong Univ.)
熱弾性方程式による音叉型水晶振動子のＱ値の解析
伊藤秀明† 玉木悠也 (信州大)LiNbO3 結合モード利用モータ振動子の負荷影響に関する解析的検討
柴田恭佑† 田村英樹 青柳学１ 高野剛浩２ 富川義朗 広瀬精二 (山形大 １室蘭工大 ２東北工大)
圧電振動型触覚センサの振動子形状の検討
工藤すばる† (石巻専修大)
周波数変化型力センサの感度に関する研究
菅原澄夫 山川将貴† 工藤すばる (石巻専修大)
圧電振動子表面誘起電荷測定用探針の量的評価
加賀重隆† 尾上守夫１ (日本電波工業 １東大)(1120)配向 AlN 薄膜を用いた純横波モード共振子
柳谷隆彦† 木内正人１ (名工大 １産総研)
ワンチップマイコンを用いたウェアラブルデバイス用超音波通信システムの開発
鈴木真ノ介† 石原学 小林幸夫 片根保１ 斉藤制海１ 小林和人２ (小山高専 １千葉大 ２本多電子)
電磁リレーにおける開離接点の動的挙動の解析
高津宣夫† 若月昇 及川雅弘 (石巻専修大)
位相共役通信への流れの影響の基礎検討
志村拓也† 渡邊佳孝 越智寛 服部岳人１ (海洋研究開発機構 １日本海洋事業)
深海域の広帯域音響通信における受信チャンネル数の影響について
越智寛† 渡邊佳孝 志村拓也 服部岳人１ (海洋研究開発機構 １日本海洋事業)【海表面のゆらぎによるコヒーレンズの時間的変動】
Jihyun Park Jong R. Yoon† Kyongbeak Ryu Joung-Soo Park１(Pukyong National Univ. １Agency Defense Development, Korea)
南極リツォホルム湾における伝搬パルス波の数値解析
土屋健伸 高橋茉里† 牛尾収輝１ 穴田哲夫 遠藤信行 (神奈川大 １国立極地研究所)
音場に対する内部波の数と間隔の影響
鶴ヶ谷芳昭† 菊池年晃１ 水谷孝一２ (NEC １防衛大 ２筑波大)
走水港内音波伝搬における潮汐の影響
小笠原英子† 中村敏明 森和義 水谷孝一１ (防衛大 １筑波大)
SiO2/Al/LiNbO3 構造を用いた Band IV 用小型 SAW デュプレクサの開発
中西秀和† 中村弘幸 鶴成哲也 上口洋輝 濱岡陽介 後藤令 岩崎行緒 (ﾊﾟﾅｿﾆｯｸ ｴﾚｸﾄﾛﾆｯｸ ﾃﾞﾊﾞｲｽ)
SiO2/高密度電極 /LiTaO3 構造共振子 SAW フィルタの肩特性改善村田崇基† 門田道雄 中尾武志 松田賢二 (村田製作所)【SiO2/金属電極/回転 Y-X LiNbO3 基板構造弾性表面波の伝搬特性の解析】
Yiliu Wang† 橋本研也 大森達也 山口正恆 (千葉大)【SAW 並びにラム波素子の高速解析のための内挿手法】
Jan H. Kuypers† Albert P. Pisano (Univ. California Berkeley)
LiNbO3 薄膜を用いた高周波ラム波デバイス
門田道雄 小上貴史† 山本観照 根来泰宏 栃下光 (村田製作所)
表面張り合わせによる SAW 素子の基礎検討
山崎貴紀† 黄啓新 宝川幸司 (神奈川工大)
SiO2 装荷による SAW 伝搬特性制御に関する実験的検討
小西くみこ† 小俣晋紀 大森達也 橋本研也 山口正恆 (千葉大)逆プロトン交換 LiNbO3 基板上のリーキー表面波伝搬特性
清水秀徳† 垣尾省司 中川恭彦 (山梨大)
埋め込み形電極構造を用いた AlGaN/GaN 素子
寺尾有司† 押山聡 黄啓新 宝川幸司 (神奈川工大)
高周波スパッタリング法による高配向 Ta2O5 圧電薄膜の作製
三井剛† 土屋彰教 垣尾省司 中川恭彦 (山梨大)
結晶粒界による薄膜 SAW 速度と損失の変化
千田進悟† 唐木智明 安達正利 古畑誠１ 樋口天光１ 舩坂司１ (富山県立大 １セイコーエプソン)

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1P5-12
1P10-1
1P10-2*

1P10-3
1P10-4*
1P10-5*
1P10-6*【水晶基板上の SAW に対する酸化アルミニウムによる速度上昇】
Wen-Ching Shih Tzyy-LongWang† Yi-Ling Kuo (Tatung Univ.)
Dye レーザ照射によるカポックの熱波信号に関する研究
得永嘉昭 吉村政俊 石丸幸大† 平間淳司 (金沢工大)
生物超音波によるアクティブソナーシステム～採餌行動時における野生コウモリの 3 次元飛行ルートと放射パルスの関係～
藤岡慧明† 萬谷重樹 飛龍志津子 力丸裕 渡辺好章 (同志社大)壁面と平行移動するロボット用の超音波センサについて
石原学† 椎名誠 鈴木真ノ介 (小山高専)
M 系列信号の同時送波による室内ターゲット検出能の検討松尾宏† 山口匡 蜂屋弘之１ (千葉大 １東工大)
FDTD 法と PSTD 法による時間領域における音場数値解析の高精度設計法
大久保寛† 大宮理生 土屋隆生１ 田川憲男 (首都大 １同志社大)
CIP 法を用いた非線形音波伝搬の 2 次元数値解析
紺野正仁† 大久保寛 土屋隆生１ 田川憲男 (首都大 １同志社大)
16:00-17:15 バルク波デバイス / 弾性表面波デバイス

1J4-1
1J4-2*
1J5-1*
1J5-2
1J5-3

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座長：近藤淳 (静岡大)LiTaO3 トランスジューサを用いた横波ＳＭＲの検討

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宇野武彦† 笠原慧 田代博之 (神奈川工大)
無線・無電極 QCM を用いたアミロイド β 凝集過程のモニタリング
福西勇志† 畑中健一 荻博次 平尾雅彦 西山雅祥 (大阪大)
凹凸 SiO2/Cu 電極/LiNbO3 構造弾性表面波デュプレクサ
中井康晴† 中尾武志 西山健次 門田道雄 (村田製作所)
ZnO/高密度電極/水晶構造高周波共振子型フィルタ
門田道雄 中尾武志 松田賢二 村田崇基† (村田製作所)
変調 IDT を用いた Cu 電極/15°YX-LiNbO3 基板構造広帯域 DMS フィルタ宮本宗† 大森達也 橋本研也 山口正恆 (千葉大)

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第 2 日：11 月 12 日(水)9:00 受付開始
9:10-10:10 一般英語口演Ⅰ
2E1*
2E2a
2E2b

2E2c

座長：酒井啓司 (東大)ピコ秒レーザー超音波法による酸化物薄膜の弾性定数測定と組織評価
舎川知広† 荻博次 中村暢伴 平尾雅彦 小高秀文１ 木原直人１ (大阪大 １旭硝子)
高温一体型超音波トランスジューサによる軽金属成形モニタリングの検討
小林牧子† 任正魁 (カナダ国立研究所)
音響整流器構造における表面音響波伝播の実時間イメージング
Sorasak Danworaphong† Timothy A. Kelf1 松田理 Oliver B. Wright 上野貢生 西島喜明
Saulius Juodkazis 三澤弘明 (北大)
ガイド波によるレール底端部検査装置の開発
常俊傑† 林高弘 村瀬守正 片岡慶太１ (名工大 １JR 東日本)

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10:10-10:15 休憩
10:15-11:00 一般英語口演Ⅱ
2E4*
2E5*
2E3*

座長：中村健太郎 (東工大)【圧電窒化アルミニウム音叉の熱弾性制動のモデリング】
Gabriele Vigevani† Jan H. Kuypers Albert P. Pisano (Univ. California Berkeley)【レーザプローブによる RF BAW 素子における横方向へのエネルギーもれの研究】
Nan Wu† 橋本研也 柏景介 大森達也 山口正恆 (千葉大)シリコンナノフォームの音響光学特性
飯野剛† 中村健太郎 (東工大)
11:00-11:05 休憩

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11:05-11:50 一般英語口演Ⅲ
2E6
2E8*
2E9*

座長：黒澤実 (東工大)【有機溶媒中に散逸した超音波エネルギーに対する液高さの影響】
Maricela Toma† Satoshi Fukutomi 朝倉義幸１ 香田忍 (名大 １本多電子)
ループ管に接続した共鳴管内にヒートポンプを設置することによる冷却効果の向上
坂本眞一† 吉田秀穂１ 坂口敦１ 渡辺好章１ (滋賀県立大 １同志社大)
SS 信号を用いた SSBL 水中音響測位に関する研究渡邊佳孝† 越智寛 志村拓也 服部岳人１ (海洋機構 １日海事)

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11:50-13:00 昼食
13:00-15:00 ポスターセッション
2P1-1*

顕微ブリルアン散乱法によるタンパク質結晶多形の音波物性
青木雄一郎† 橋本英二 金沢一史 池祐治 小島誠治 (筑波大)
2P1-2
ブリルアン散乱による広い濃度範囲のカリウムホウ酸塩ガラスの弾性的性質
川島充† 松田裕 布川泰輝 間宮精一 小玉正雄１ 小島誠治 (筑波大 １崇城大)2P1-3*
超音波共鳴法を用いた C12A7 単結晶の弾性定数計測山本昌孝† 垂水竜一 平尾雅彦 平野正浩１ 金聖雄１ 細野秀雄１ (大阪大 １東工大)
2P1-4
ｈ－BN セラミックの超音波による研究（Ⅲ）
柏倉伸男† 佐藤元樹 山家光男 秋田正之 上岡宏彰 (岐阜大)2P1-5*
分極処理が水熱合成 PZT 多結晶膜の特性におよぼす影響
入澤信哉† 遠藤聡人１ 黒澤実２ 川島徳道 竹内真一 (桐蔭横浜大 １産総研 ２東工大)
2P1-6*【介在物が消失する複合体の横波音速】
Q. Hung Truong† Yong-Hun Eom Changho Lee１ Jong-Sub Lee (Korea Univ. １Georgia Inst. Tech.)
2P1-7*【複合介在物のセメント化にともなう弾性定数変化】
Changho Lee† Q. Hung Truong１ Hyung-Koo Yoon１ Jong-Sub Lee１ (Georgia Inst. Tech. １Korea Univ.)
2P2a-17* 線形周期変調信号を用いたパルス圧縮とドップラーシフト補正による高精度距離計測
平田慎之介† 黒澤実 片桐崇１ (東工大 １すてきな)
2P2a-18 エネルギー閉じ込めモード厚み振動を利用した微小液面レベル変化の検知山田顕† 本田斐聡 堀内修平 木内哲也 (東北学院大)2P2a-19 超音波適応信号とパルス圧縮を併用した距離測定陶良† 千村大 本岡誠一 (千葉工大)
2P2a-20 超音波を用いた水素センサーに関する研究加藤喜峰† (九大)
2P2a-21 電気機械結合系における容量比の更に精密な評価
大木道生† (防衛大)2P2a-22* 等価回路モデルに基づくラウドスピーカのインパルス応答の改善
井上俊二† 若槻尚斗 水谷孝一 (筑波大)
2P2b-10* 矩形音源による反射点探索の少数要素アレイの導入による改善
増山裕之† 水谷孝一１ (鳥羽商船高専 １筑波大)
2P2b-11* パルス光源を用いるガラス板内 Lamb－Type Wave の可視化
西宮康治朗† 水谷孝一 若槻尚斗 大淵武史 山本健 (筑波大 １関西大)
2P2b-12* 音響ホログラフィ法を用いる二次元音場からの三次元音場再構成
大淵武史† 水谷孝一 若槻尚斗 西宮康治朗 増山裕之１ (筑波大 １鳥羽商船高専)
2P2b-13* SLDV を用いた極浅層地中映像化に関する研究阿部冬真† 杉本恒美 (桐蔭横浜大)
2P2b-14* 冠水土壌中での極浅層超音波イメージングに関する研究
瀬尾邦彦† 白川貴志 杉本恒美 (桐蔭横浜大)
2P2b-15* パルス圧縮を用いた地中映像分解能の改善
川﨑拓† 杉本恒美 (桐蔭横浜大)
2P2b-16* 【水侵超音波走査法によるポアソン比マッピングシステム】
SeoYoung Oh† Young H. Kim Yosub Shin Hyun-Joon Cho１
(Korea Sci. Acad. １Advanced Inst. Quality and Safety)
2P2b-17 【超音波顔識別システムの開発】
Zhenwei Miao Wei Ji Yong Xu Jun Yang† (Chinese Acad. Sci.)
2P2c-6* 電磁超音波探触子を用いた移動型配管探傷センサの開発
大川悠助† 村山理一 諸岡秀昭 山下雄介 (福岡工業大)

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2P2c-7

非接触空中超音波によるパイプ円周方向探傷の開発
高橋雅和† 星野秀和 小倉幸夫 北川秀昭１ 楠元淳一１ 金谷章宏１ 西野秀郎２(ジャパンプローブ １九州電力 ２徳島大)
2P2c-8
非線形超音波法を用いた Cr-Mo-V 鋼のクリープ損傷評価
大谷俊博† (湘南工大)
2P2c-9* 熱損傷を受けたグラナイトの非線形超音波計測
Claude Inserra† 琵琶志朗 Youqing Chen (京大)
2P2c-10 逐次最小 2 乗プレフィルタリングを用いるランダムアレイの最適時間反転集束法
Dengyong Ma Jun Yang† (Chinese Acad. Sci.)
2P5-13
センサネットワーク用弾性表面波ガスセンサの高性能化の研究
平泉康志† 青木宏融 渡邊友章 松田潤治 疋田光孝 (工学院大)2P5-14* 多種類の揮発性有機化合物分析のためのボール SAW ガスクロマトグラフシステム
山本祐太朗† 赤尾慎吾 佐久間正典 小針健太郎 野口和洋１ 辻俊宏 中曽教尊 山中一司
(東北大 １凸版印刷)
2P5-15
IDT 位置を最適化した方位制御ボール SAW 素子の開発と伝搬特性の評価
柳沢恭行† 大木恒郎 中曽尊教 山中一司１ (凸版印刷 １東北大)
2P5-16* 軸外スピンコート法を用いたボール SAW センサの感応膜の作製
小針健太郎† 山本祐太朗 佐久間正典 赤尾慎吾１ 辻俊宏 山中一司 (東北大 １凸版印刷)
2P5-17弾性表面波を用いた匂い供給装置の開発
文字太郎† 齋藤敦史 野村徹 (芝浦工大)
2P5-18* SAW 圧電結晶を用いたマイクロ実験室
安田宣之† 杉本光範 近藤淳 (静岡大)2P5-19* 横波型弾性表面波を用いた粘度標準液の測定
森田武† 杉本光範 近藤淳 (静岡大)
2P6-1
気泡数の変動を取り入れたキャビテーション・ノイズの数値シミュレーション
安井久一† 辻内亨 Judy Lee 小塚晃透 砥綿篤哉 飯田康夫 (産総研)
2P6-2*
１ＭＨz ソノケミルミネセンスのパルス波依存性
小澤綾子† 崔博坤 (明大)
2P6-3
ソノルミネセンスにおける Na 発光と連続スペクトル成分の時間空間分離崔博坤† 阿部将吾 (明大)2P6-4*
気泡の二次的な音響放射が他気泡の振動位相に与える影響
藤川貴彬† 吉田憲司 渡辺好章 (同志社大)2P6-5*
超音波場における二つの壁面付着気泡の崩壊挙動：同時発生する複数の微小流
吉田憲司† 渡辺好章 (同志社大)2P6-6
ソノケミカル反応容器の音場設計における圧電共振特性の FEM 解析
岡田長也† 佐藤正典 朝倉義幸 (本多電子)
2P6-7
超音波霧化中の多泡性ソノルミネッセンス
原田久志† 岩田尚大 白鳥啓介 (明星大)
2P7a-14 光アシスト超音波速度変化イメージング法による初期癌検出のための基礎的検討
堀中博道† 川上俊介 石橋賢 松山哲也 和田健司 松中敏行 (大阪府大)2P7a-15* 医用超音波イメージングにおけるエコー信号間の相関を用いた微小結石検出法
瀧宏文† 松田哲也 佐藤亨 (京大)
2P7a-16* 周波数領域干渉計法による複数目標検出における高分解能超音波イメージングの実験検討
木村智樹† 瀧宏文 阪本卓也 佐藤亨 (京大)
2P7a-17* ノイズ源を遮蔽するビーム設計
山本真理子† 梅村晋一郎１ 東隆 (日立 １東北大)
2P7a-18 【非線形超音波画像のための最適 2 次フィルタ】
Pornchai Phukpattaranont† Chusak Limsakul (Prince Songkla Univ.)
2P7a-19 固有値分解による組織境界イメージング
増井裕也† 東隆 佐々木一昭１ (日立 １農工大)
2P7a-20 ずり弾性率と力源の再構成
炭親良† 末包明夏 (上智大)
2P7b-1* 【超音波により生成したたんぱく質マイクロバブルの評価：生成から崩壊まで】
Judy Lee† 砥綿篤哉 安井久一 小塚晃透 辻内亨 飯田康夫 (産総研)
2P7b-2流路分岐部における照射超音波の変化に対するマイクロカプセルの流路選択効率の検討
村松悠佑† 上田沢美 中元隆介 中屋敷悠介 桝田晃司 石原謙１ (農工大 １愛媛大)
2P7b-3* 多周波超音波イメージングのための二周波駆動振動子
吉住夏輝† 斎藤繁実１ 小山大介２ 中村健太郎２ 秋山いわき (湘南工大 １東海大 ２東工大)

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2P7b-4
2P7b-5*
2P7b-6*
2P7b-72P8-1*
2P8-2*

2P8-3

2P8-4*

2P8-5

2P8-6*
2P8-7*
2P8-8*

2P8-9

2P8-10*

2P9-1
2P9-2
2P9-3
2P9-4
2P9-5*

2P10-7
2P10-8*
2P10-9*超音波分子イメージングのための高出力アレイプローブ
東隆† 薗田志保 川畑健一 梅村晋一郎１ (日立 １東北大)微小超音波プローブ用音響レンズに関するスケールサイズ実験と解析の音場特性比較内藤史貴† 松本さゆり１ 高橋茉里 土屋健伸 遠藤信行 (神奈川大 １港空研)
水熱合成法による PZT 多結晶膜を用いた小型超音波プローブの指向性に対するエッジモード共振の影響長谷川智仁† 黒澤実 竹内真一１ (東工大 １桐蔭大)
酸化亜鉛を添加したシリコーンゴム製低減衰音響レンズの機械強度特性
山本紀子† 山下洋八１ 逸見和弘 (東芝 １東芝ﾘｻｰﾁｺﾝｻﾙﾃｨﾝｸﾞ)導波路管型超音波洗浄機用振動子の試作
鈴木一成† 潘毅 岡野勝一 副島潤一郎 小池義和１ (カイジョー １芝浦工大)【強力超音波によるアルミ合金の核生成の促進】
Jeong IL Youn1† Byoung IL Kang Beom Suk Han１ Young Jig Kim(Sungkyunkwan Univ. １Korea Automotive Tech.)【生活汚泥処理における超音波の効果】
Jiho Park Young Uk Kim† Jong-Sub Lee１ Mian Chen Wang２(Myongji Univ. １Korea Univ. ２Pennsylvania State Univ.)【大型ソノリアクタ設計のための音場分布測定】
Younggyu Son1† Myunghee Lim Ik-Beom Park１ Mingcan Cui1 Jeehyeong Khim
(Korea Univ. １Gyeonggi-do Instit. Health Environment)【超臨界 CO2 と超音波を用いた汚泥からの金属抽出】
Ik B. Park† Younggyu Son Il S. Song１ Kyung H. Na１ Jongchan Kim１ Jeehyeong Khim
(Korea Univ. １Gyeonggi-do Instit. Health Environment)【ディーゼルエンジン排出微粒子を含む泥の洗浄における超音波照射の最適化】
Beomguk Park† Jihoon Cha Younggyu Son Myunghee Lim Jeehyeong Khim (Korea Univ.)
超音波振動を用いた絶縁被膜鉄粒子の圧縮成形
菊池慎一† 小山大介 中村健太郎 Hyun-Loc Cha１ (東工大 １KITECH)【超音波振動を用いて圧縮成型した SMC モータコアの磁気的特性の比較】
Hyun Rok Cha† 菊池慎一１ Seoung Kyu Jeon Sung Ho Lee Cheol Ho Yun１ 中村健太郎１(KITECH １東工大)【Die Attach Film を介してガラス基板上に半導体 Die を溶着する室温超音波溶接】
Siu Wing Or† Sui Yin Wong Ho Chi Wong Yiu Ming Cheung１ Ping Kong Choy１(Hong Kong Polytech. Univ. １ASM Assembly Automation)【マイクロ電子部品用超音波ホーンの設計】
Minseok Bae† Young H. Kim Jeong-Hoon Moon１ Kyung-soo Kim２
(Korea Sci. Acad. １Suwon Sci. Coll. ２Changjo Eng.)
単一非球面音響レンズの収束特性の精密計測
松本さゆり 進雄一†１ 内藤史貴１ 土屋健伸１ 遠藤信行１ 武山芸英２ (港空研 １神奈川大 ２ジェネシア)周囲雑音イメージングのためのアプラナート音響レンズの集束音場
森和義† 小笠原英子 中村敏明 佐藤裕治１ 土屋健伸２ 遠藤信行２ (防衛大 １筑波大 ２神奈川大)
差動接続を用いた屈曲円板型低周波送波器アレイの広帯域化に関する FEM 解析
山本満† 井上嵩梓 芝博史 北村佑太 (NEC)【バーレル板フレクステンショナルトランスデューサの最適設計】
Hoeyong Kim Yongrae Roh† (Kyungpook National Univ.)【ソーナードームからの反射波の円筒状アレイの放射インピーダンスへの影響の解析】
Jungsoon Kim† Moojoon Kim１ Kanglyeol Ha１ Heeseon Seo２ Cheeyoung Joh２
(Tongmyong Univ. １Pukyong Univ. ２Agency Defense Development)
FDTD 法と境界積分方程式法の結合解法による音場シミュレーション
土屋隆生† 熊谷篤志 (同志社大)
通信系のインパルス応答を考慮した PSK 変調方式
海老原格† 水谷圭一１ 若槻尚斗 水谷孝一 森川浩一 (筑波大 １東工大)
差動位相偏移変調を用いる空中音響通信における通信領域の局所性
水谷圭一† 海老原格１ 若槻尚斗１ 水谷孝一１ (東工大 １筑波大)

15:00-15:50 招待講演Ⅰ
2INV1

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337

座長：山中一司 (東北大)

高温超音波プローブ及びその応用可能性

339
任正魁† 小林牧子 （カナダ国立研究所）

15:50-16:40 招待講演Ⅱ
2INV2

座長：梅村晋一郎 (東北大)【マイクロバブルと超音波：医用イメージングにおける新しいパートナー】
Peter N. Burns† (University of Toronto)

341

16:40-16:45 休憩
16:45-17:15 一般英語口演Ⅳ
2E7a
2E7b

座長：松川 真美 (同志社大)【2 次ボルテラシステム同定に基づいた非線形超音波信号の分離】
Pornchai Phukpattaranont† (Prince Songkla Univ.)【超音波顕微鏡を用いた骨の微小領域の弾性評価：ナノインデンテーションとの比較】
Pascal Laugier† Fabienne Rupin Davy Dalmas１ Francoise Peyrin２ Kay Raum３ Etienne Barthel１ Amena Said
(Univ. Paris 06 １Unite Mixte CNRS/Saint-Gobain ２CNRS ３Martin Luther Univ. Halle-Wittenberg)

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345

17:15-17:30 表彰式
17:45-

懇親会

第 3 日：11 月 13 日(木)9:00 受付開始
9:10-10:10 映像法 / 非破壊検査
3J2b-1*

座長：荻博次 (大阪大)

紫外励起光熱変換顕微鏡の開発と無染色生細胞の観察347
藤井宣行† 原田明 (九大)

3J2b-23J2c-13J2c-2*

超音波による電気・磁気特性の画像化349

生嶋健司† 樋田啓１ 小宮山進１ (農工大 １東大)
サブハーモニック超音波フェーズドアレイ SPACE を用いた閉じた応力腐食割れの計測小原良和† 遠藤宏明 三原毅１ 山中一司 (東北大 １富山大)
二層型圧電振動子を用いた閉じた亀裂から発生する Lamb 波の非線形成分の検出福田誠† 今野和彦 (秋田大)

351
353

10:10-10:15 休憩
10:15-10:45 ソノケミストリー
3J6-1
3J6-2

座長：松岡辰郎 (名古屋大)

超音波反応槽内における気泡構造形成過程の観察
飯田康夫† 砥綿篤哉 安井久一 小塚晃透 辻内亨 Judy Lee (産総研)
超音波照射時間の変化によるナノダイヤモンド微粒子の分散への影響
内田武吉† 菊池恒男 青木貴宏１ 川島徳道１ 竹内真一１ (産総研 １桐蔭横浜大)

355
357

10:45-10:50 休憩
10:50-11:50 強力超音波
3J8-1
3J8-2
3J8-3
3J8-4*

座長：工藤すばる (石巻専修大)

V 型超音波モータを用いた高速高分解能ステージ
阿隅一将† 福永了一 藤村健 黒澤実１ (太平洋セメント １東工大)
導波路管型超音波洗浄機用振動子の CMP 後洗浄への適用-スポット型振動子の洗浄評価鈴木一成 潘毅† 岡野勝一 副島潤一郎 小池義和１ (カイジョー １芝浦工大)
無鉛圧電セラミックスと超音波洗浄機への応用
董敦灼† 浜口佑樹 舞田雄一 山森春男 高橋和利１ 寺嶋良充１ (本多電子 １富士チタン工業)
エアロゾルデポジション法による PZT 膜を用いた高周波超音波プローブの音響特性
遠藤聡人† 明渡純 (産総研)
11:50-13:00 昼食

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365

13:00-15:00 ポスターセッション
3P2b-1

牛骨を透過する超音波波面の可視化による検討367
大野正弘† (千葉工大)

3P2b-2*

超音波 CT 法による内臓脂肪測定のファントム評価実験369
川本幸一郎† 山田晃 田村美希 (農工大)

3P2b-3

直角四方向観測型超音波逆散乱トモグラフィ371
山田晃† (農工大)

3P2b-4*
3P2b-5
3P2b-6
3P2b-7*
3P2b-83P2b-9*3P2c-1*3P2c-2*3P2c-3*3P2c-43P2c-5
3P6-8*
3P6-9*
3P6-10
3P6-11*
3P6-12*

3P6-13*

3P6-14*
3P6-15*
3P6-16*3P6-17*
3P6-183P6-19*3P6-20

画像処理に基づいた圧電デバイス振動変位分布測定法の改良
橘健太朗† 渡部泰明 今枝憲幸 五箇繁善 佐藤隆幸 関本 仁 (首都大)フォトリフラクティブ映像法による弾性波の可視化三浦崇広† 落合誠 小原良和１ 山中一司１ (東芝電力ｼｽﾃﾑ １東北大)
円、楕円、放物線境界での表面音響波の反射や収束のイメージング
友田基信† Oliver B. Wright 上野貢生 西島喜明 Saulius Juodkazis 三澤弘明 (北大)
バルク音響振動子における GHz 音響波伝搬の実時間イメージング
藤倉崇† 松田理 Oliver B. Wright Jeremy Masson１ Sylvain Ballandras１ (北大 １FEMTO-ST)
くさび構造におけるラム波伝播の実時間イメージングと分散解析
松枝真之介† 友田基信 松田理 Oliver B. Wright (北大)
不等角間隔投影データを用いた音響トモグラフィ法による矩形空間内部温度分布計測
南出歩† 水谷孝一 若槻尚斗 (筑波大)【構造物の損傷を検出する圧電振動センサ】
Hyeoksang Kwon† Byungsoo Kim Yongrae (Kyungpook National Univ.)【矩形き裂におけるラム波の反射と透過】
Byungsoo Kim † Hyeoksang Kwon Yongrae (Kyungpook National Univ.)
角鋼片の内部欠陥の超音波による検出
三井秀人† 水谷孝一 若槻尚斗 山野正樹１ (筑波大 １住友金属)【パイプ欠陥からのガイド波の可視化とモード解析】
Nor Salim Bin Muhammad† 林高弘 村瀬守正 神谷庄司 (名工大)反射体を利用した高効率ガイド波励起検出法による欠陥の検出
西野秀郎† 小倉圭二 吉田憲一 (徳島大)【パイロット規模の超音波反応装置を用いた廃油からバイオディーゼル生成】
Le Tu Thanh† 興津健二 定永靖宗 竹中規訓 坂東博 (大阪府大)【ディーゼルオイル油汚染土壌の界面活性剤添剤を用いた超音波洗浄】
Jihoon Cha† Beomguk Park Younggyu Son Mingcan Cui Jeehyeong Khim (Korea Univ.)
超音波による乳酸発酵促進と発酵温度との関係
小山聡† 増澤信義 (武蔵工大)【汚水のタンニンの生分解性についての増強効果】
Junghyun Lim† Eunju Cho Mingcan Cui Myunghee Lim Jeehyeong Khim (Korea Univ.)【大腸菌の塩素殺菌の超音波照射効果】
Hoang Lam Pham† Hyunjun Kim Myunghee Lim Iordache Ioan１ Jeehyeong Khim
(Korea Univ. １Nat. Res. Development Inst., Romania)【大腸菌の超音波殺菌に対する超音波強度の効果】
Hyunjun Kim† Hoang Lam Pham Myunghee Lim Mingcan Cui David Elena１ Jeehyeong Khim
(Korea Univ. １Nat. Res. Development Inst., Romania)【色素の生分解脱色に対する超音波による増強効果】
Eunju Cho† Junghyun Lim Mingcan Cui Younggyu Son Jeehyeong Khim (Korea Univ.)
キャビテーションバブル気液界面領域の物理化学的解明
南齋勉† 興津健二 竹中規訓 坂東博 (大阪府大)混合溶液中におけるフェノールとシクロヘキサノールの超音波分解
石川健太† 南齋勉 興津健二 竹中規訓 坂東博 (大阪府大)炭素数及び不飽和度の異なる各種ジカルボン酸水溶液の超音波化学反応
守谷怜† 成毛由紀夫 田中寿 原田久志 (明星大)
超音波化学反応性能に及ぼす攪拌条件の影響
安田啓司† 松浦一真 堀添浩俊 (名大)【フェノールの超音波分解における過酸化水素と周波数の影響】
Myunghee Lim† Younggyu Son Mingcan Cui Jeehyeong Khim (Korea Univ.)
液体中の含有気体が超音波照射下のフリーラジカル発生閾値におよぼす影響
岡田健吾† 工藤信樹 Mariame A. Hassan１ 近藤隆１ 山本克之 (北大 １富山大)

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3P7a-1

加圧方法最適化による組織内歪み均一性の向上及び elastogram の改善佐藤翔† 佐藤隆幸 相浦紗雪 渡部泰明 五箇繁善 関本仁 (首都大)3P7a-2横方向変調の最適化
炭親良† 小宮勇一 宇賀真也 (上智大)
3P7a-3* 仮想ビームでの双曲線走査による横方向変調と変位ベクトル計測
近藤健悟† 山川誠１ 椎名毅１ (筑波大 １京大）
3P7a-4* 配列型合成開口処理と制限付き最小二乗法を用いた高速二次元変位ベクトル推定精度の検討
横山亮太† 八木晋一 田村清１ 佐藤正和２ (明星大 １アロカ ２マイクロソニック)
3P7a-5* グラフカットを用いた弾性イメージング赤澤直人† 大久保寛 田川憲男 (首都大)3P7a-6微小変位検出に基づく精細組織弾性イメージング
相浦紗雪† 佐藤隆幸 佐藤翔 渡部泰明 関本仁 (首都大)3P7a-7* 超音波乳腺画像の採取・表示システムの開発小沢智志† 斎藤北茉１ 佐藤正和２ 橘内洋２ 入江喬介２ 吉沢昌純１ 大久保寛 田川憲男 横井浩３
本田伸行４ (首都大 １都立高専 ２マイクロソニック ３横井整形外科 ４寺元記念病院）
3P7a-8
超音波画像における細径血管抽出のための前処理手法の評価
大澤康明† 伊東正安 (電機大)3P7a-9* 断層像の動画像処理による左心室運動ベクトルの交点描出法とその応用
高橋累† 桝田晃司 吉永崇 松浦宏尚 内堀駿 (農工大)3P7a-10 肝エコー画像におけるスペックルリダクションへの独立成分解析の適用
山口匡† 須鎗弘樹 (千葉大)
3P7a-11 血流内のずり速度推定における血管壁運動の影響新田尚隆† (産総研)
3P7a-12 高周波超音波を用いた橈骨動脈壁粘弾性計測法の基礎実験による精度評価
池下和樹† 長谷川英之 金井 浩 (東北大)
3P7a-13 心筋収縮拡張特性計測における 2 次元相関窓長と探索領域の最適化
本庄泰徳† 長谷川英之 金井 浩 (東北大)3P7b-8* 近距離音場における ISPTA を用いた Soft-Tissue Thermal Index(TIS)算出の問題点
吉岡正裕† (産総研)
3P7b-9* 超音波凝固切開装置の生体作用の基礎検討
大屋優† 山口匡 林秀樹 蜂屋弘之１ (千葉大 １東工大)
3P7b-10 穿刺型超音波顕微鏡用面走査手法の開発
吉澤昌純† 江本龍二 川畑宏貴 入江喬介１ 伊東紘一２ 守屋正３
(都立産技高専 １マイクロソニック ２常陸大宮済生会病院 ３首都大)3P7b-11* 送信信号の直接受信を回避可能なインライン送受信システム
田邉将之† 大久保寛 田川憲男 (首都大)3P7b-12* インライン送受信システムにおいて受信機として用いる PVDF の整合層機能
宮田誠† 田邉将之 大久保寛 田川憲男 (首都大)3P7b-13* 【高周波超音波を用いたヒトリンパ節の散乱体サイズの 3 次元評価】
Jonathan Mamou† Alain Coron１ Masaki Hata２ Junji Machi２ Eugene Yanagihara２ Pascal Laugier１
Ernest J. Feleppa (Riverside Research Inst. １UPMC Univ. Paris 06 ２Univ. Hawaii)
3P7b-14* 【ウシ皮質骨中の超音波伝搬特性の周波数依存性】
Guillaume Haïat† Magali Sasso１ Salah Naili１ 松川真美２ (Univ. Paris 7 １Univ. Paris 12 ２同志社大)
3P7b-15* 【海綿骨中の多重散乱と吸収が音速分散に及ぼす影響】
Guillaume Haïat† Alain Lhémery１ Frédéric Padilla２ Pascal Laugier２ Salah Naili３(Univ. Paris 7 １Commissariat à l’énergie Atomique ２Univ. Paris 6 ３Univ. Paris 12)
3P7b-16 In vivo 海綿骨弾性定数の評価
大谷隆彦† 真野功１ 辻本敏行２ 山本真人３ 豊島良太３ 中弘志４
(同志社大 １応用電機 ２堀場製作所 ３鳥取大 ４大阪市大)3P7b-17* ウシ皮質骨中の超音波縦波音速の異向性と HAp 結晶配向矢追佑一郎† 山本和史１ 柳谷隆彦２ 松川真美 山崎薫１ 長野昭１ (同志社大 １浜松医大 ２名工大)3P7b-18 海綿骨中の軟組織が超音波の伝搬に与える影響
佐伯崇† 久保智宏 松川真美 長谷芳樹１ (同志社大 １神戸高専)
3P7b-19 層状構造海綿骨ファントム中を斜方向伝搬する高速波・低速波における骨梁要素の影響
細川篤† (明石高専)
3P7b-20* 体内音場解析のための“ディジタル人体弾性モデル”実現に向けて長谷芳樹† 細川篤１ 阪口剛史２ 松川真美３ 渡辺好章３ (神戸高専 １明石高専 ２奈良医大 ３同志社大)3P8-11弾性表面波素子による金接合における接合状態の検討
成瀬健悟† 森きよみ１ 渡辺裕二１ (精電舎電子工業 １拓殖大)

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3P8-12
3P8-13
3P8-14
3P8-15
3P8-16*
3P8-17*
3P8-18*3P8-19*3P8-20*
3P8-21*

3P8-22
3P8-23
3P8-24*
3P8-25*
3P8-26
3P8-273P8-28

超音波浮揚における強力音場生成のための音源および反射板の検討
小塚晃透† 安井久一 辻内亨 Judy Lee 砥綿篤哉 飯田康夫 (産総研)
凸端駆動による縞モードたわみ振動板型空中超音波音源
三浦光 石川整† (日大)
有限振幅の空中超音波を用いてモルタルの受熱を判定する方法の検討
伊藤洋一 朝倉直人† (日大)
音波の入射角度を変更できる線集束空中超音波音源とその音場
伊藤洋一† (日大)
ループ管型熱音響システムの低温度差駆動に向けた分岐管の利用
石野貴廣† 坂本眞一１ 西川昌宏 渡辺好章 (同志社大 １滋賀県立大)熱音響システムにおいて積層メッシュが音から熱へのエネルギー変換に及ぼす影響
坂口敦† 坂本眞一１ 辻良行 渡辺好章 (同志社大 １滋賀県立大)熱音響システムにおいて薄膜の設置位置が管内音場に与える影響
西川昌宏† 坂本眞一１ 石野貴廣 渡辺好章 (同志社大 １滋賀県立大)屈曲超音波伝搬路における表面粒子運動の回転位相解析
田中亮† 田邉将之 友田耕平 大久保寛 田川憲男 (首都大)カンチレバーの共振を利用した球体の精密回転マニピュレータの開発
冨田輝之† 辻俊宏 山中一司 (東北大)
超音波モータを用いたスピーカの制御方法
増田裕輔† 東田啓吾 千葉俊輔 根岸廣和１ 大賀寿郎１ 前田和昭２ 久保田一
(千葉工大 １MIX 音研 ２TOA)【超音波リニアモータの性能向上のための重りの効果の評価】
Chaodong Li† Jian Jin (Shanghai University)
高速回転超音波アクチュエータの予圧制御と等価回路解析
青柳学† 関舞子 高野剛浩１ 田村英樹２ 富川義朗２ (室蘭工大 １東北工大 ２山形大)
縦１次屈曲 1 次多重モード利用矩形板型超音波モータ
福永了一† 阿隅一将 浅倉綾太 稲田豊 (太平洋セメント)
超音波モータの弾性保持機構
井上尚武† 石井孝明 (山梨大)
多自由度超音波マイクロモータの 2 次元アレイ化設計
合田泰之† 小山大介 中村健太郎 (東工大)
自走式超音波浮上２次元ステージ
小山大介† 中村健太郎 (東工大)
屈曲振動円板を用いた非接触型超音波モータの回転速度特性に及ぼすギャップ長の影響
山吉康弘† 中川友裕 田村英樹 広瀬精二 (山形大)
15:00-16:00 医用超音波イメージング

3J7a-1*
3J7a-2*
3J7a-3
3J7a-4*

3J7b-1
3J7b-2*
3J7b-3
3J7b-4

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507

座長：山越芳樹 (群馬大)心筋歪みイメージングのための高性能の時空間的変位平滑化フィルター
布樹輝† 椎名毅１ 山川誠１ 滝沢穂高 (筑波大 １京大)
肝線維症の定量化のための散乱体密度に依存するパラメータの検討
江塚大史† 山口匡 神山直久１ 蜂屋弘之２ (千葉大 １東芝ﾒﾃﾞｨｶﾙｼｽﾃﾑｽﾞ ２東工大)
赤血球凝集度評価を目指した超音波散乱波の周波数特性の散乱体サイズ依存性の計測
齋藤靖好† 長谷川英之 金井浩 (東北大)血管壁評価に向けた脈波解析
齋藤雅史† 松川真美 渡辺好章 (同志社大)
16:00-16:05 休憩
16:05-17:05 医用超音波（その他）

475

509
511
513
515

座長：山田晃 (農工大)

超音波の周波数走査法によるターゲット壁への微小気泡の付着
山越芳樹† 三輪空司 (群馬大)
相変化ナノ液滴の粒径による音響特性の違いを用いた多機能超音波イメージング
浅見玲衣† 東隆 川畑健一 (日立)
純水を発熱体とする calorimetry 法による超音波パワー計測－諸問題を軽減する水温測定法の提案－
菊池恒男† 内田武吉 (産総研)
超音波メス使用時の発熱量推定のための軟組織の粘弾性特性推定
鈴木直貴† 長谷川英之 金井 浩 (東北大)
17:05-17:15 閉会式

517
519
521
523

The 29th Symposium on Ultrasonic Electronics (USE 2008) Program†Speaker*Applying to Young Scientists Award
Tuesday, November 11
09:00- Registration
09:50 Opening Ceremony
10:00-10:45 Ultrasonic properties of materials, Phonon physics

1J1-1*
1J1-2

1J1-3*

Chair: Kazushi Yamanaka (Tohoku Univ.)

Study on fast recovery of elastic constants of metallic thin films by resonant-ultrasound spectroscopy
Takeo Nakashima†, Nobutomo Nakamura, Hirotsugu Ogi, Masahiko Hirao, Masayoshi Nishiyama (Osaka Univ.)
Characterization of thermal properties of porous Si film adsorbed with CdSe quantum dots using photoacoustic
techniqueJun Kogakura†, Yushi Kato, Qing Shen, Taro Toyoda (Univ. Electro-Com.)
Epitaxial KNbO3 films grown on SrRuO3/SrTiO3 using hydrothermal method and their electromechanicalproperties
Mutsuo Ishikawa†, Satoru Utsugi, Takashi Fujisawa, Shintaro Yasui, Tomoaki Yamada, Minoru Kurosawa, Takeshi
Morita１, Hiroshi Funakubo (Tokyo Instit. Tech.; １Univ. Tokyo)

1

3

5

10:45-10:50 Break
10:50-11:50 Acousto-optics / Underwater ultrasound
1J3-1*
1J3-2*
1J9-1
1J9-2*

Chair: Takenobu Tsuchiya (Kanagawa Univ.)

Vibration sensing by using Fabry-Perot interferometer with FBG reflectors
Atsushi Wada†, Hiroyuki Somatomo, Satoshi Tanaka, Nobuaki Takahashi (National Defense Acad.)High efficient optical mode converter using Lamb wave
Koki Saito† , Yasuhiko Nakagawa, Shoji Kakio (Univ. Yamanashi)
Detection of objects in shadow region using time reversal
Yoshiaki Tsurugaya†, Toshiaki Kikuchi１, Koichi Mizutani２ (NEC; １National Defence Acad.; ２Univ. Tsukuba)
Design for aplanatic Fresnel acoustic lens
Yuji Sato†, Koichi Mizutani, Naoto Wakatsuki, Toshiaki Nakamura１ (Univ. Tsukuba; １National Defense Acad.)

7
9
11
13

11:50-13:00 Lunch
13:00-14:00 Measurement techniques
1J2a-1*

1J2a-21J2a-3*1J2a-4Chair: Masahiro Ohno (Chiba Inst. of Tech.)

Measurement model for propagation characteristics of leaky surface acoustic waves by the line-focus-beamultrasonic material characterization system
Kenji Otsu†, Mototaka Arakawa, Jun-ichi Kushibiki (Tohoku Univ.)
Investigation of carrier recombination processes in GaAs/AlAs multiple quantum wells using piezoelectric
photothermal and surface photovoltage techniques
Ping Wang†, Kentaro Sakai, Atsuhiko Fukuyama, Tetsuo Ikari (Miyazaki Univ.)
Vibrational modes of semiconductor nanopillars studied by picosecond ultrasonics
Hirotaka Sakuma†, Motonobu Tomoda, Osamu Matsuda, Takashi Fukui, KatsuhiroTomioka, Oliver B. Wright(Hokkaido Univ.)
Surface excitation of shear horizontal waves
Morio Onoe† (Univ.Tokyo)

15

17
19

21

14:00-16:00 Poster Session
1P1-8
1P1-9
1P1-10Vibrational modes in rectangular cross-section nanowire superlattices
Seiji Mizuno†, Yushi Nakamura (Hokkaido Univ.)
Electrical properties of textured (Bi1/2K 1/2)TiO3-BaTiO3 ceramics
Masahiro Nemoto†, Yuji Hiruma, Hajime Nagata, Tadashi Takenaka (Tokyo Univ. Sci.)
Exact analysis of Lamb waves in piezoelectric membranes with distinct electrode arrangements
Yung Yu Chen† (Tatung Univ.)

23
25
27

1P1-11*

1P1-12
1P1-13
1P1-14*

1P1-15*
1P1-16*
1P1-17*
1P1-18*
1P2a-1
1P2a-2
1P2a-3

1P2a-4

1P2a-5
1P2a-6*
1P2a-7

1P2a-8*
1P2a-9
1P2a-10
1P2a-11*
1P2a-12*
1P2a-13
1P2a-14*
1P2a-15*
1P2a-16*
1P3-1
1P3-2*

Effect of atmospheric pressure plasma treatment on ultrasonic bumpless flip chip bonding
Jung-Lae Jo†, Ja-Myeong Koo, Jong-Bum Lee, Seung-Boo, Jung Jeong-Hoon Moon１(Sungkyunkwan Univ.; １Suwon Sci. Coll.)
Effect of bonding parameters on ultrasonic bonding of flexible printed board (FPCB) on glass substrate
Jong-Bum Lee†, Jong-Gun Lee, Jung-Lae Jo, Ja-Myeong Koo, Seung-Boo Jung (Sungkyunkwan Univ.)
Rheology measurement of surfactant solutions by electro-magnetically spinning viscometer
Maiko Hosoda†, Hideo Ogawa, Hiroyasu Nomura, Keiji Sakai１ (Tokyo Denki Univ.;１Univ. Tokyo.)Phase relations and electrical properties of the lead-free (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 ternary
systems
Yuji Hiruma†, Hajime Nagata, Tadashi Takenaka (Tokyo Univ. Sci.)
Elastic and piezoelectric coefficients of LiNbO3 single crystal: RUS measurement and group theoretical analysis
Yuki Hayashi1†, Ryuichi Tarumi, Masahiko Hirao (Osaka Univ.)
Study on viscoelastic properties of polystyrene films by a QCM-D technique
Aiko Shirai †, Yohei Asano, Masahiro Maebayashi１, Shinobu Koda (Nagoya Univ.; １Meijo Univ.)
Electromechanical coupling coefficient of semiconducting piezoelectric crystal measured by Brillouin scattering
Taisuke Yoshida†, Takahiko Yanagitani１, Mami Matsukawa (Doshisha Univ.; １Nagoya Inst. Tech.)Shear mode piezoelectric properties of KNbO3-based ferroelectric ceramics
Kouhei Hikita†, Yuji Hiruma, Hajime Nagata, Tadashi Takenaka (Tokyo Univ. Sci.)
Evaluation of synthetic silica glasses by the ultrasonic microspectroscopy technology
Mototaka Arakawa†, Hideki Shimamura, Jun-ichi Kushibiki (Tohoku Univ.)
Thermal diffusivities of high polymer transparent films investigated by laser induced thermal wave probing
Yoshiaki Tokunaga, Hiroyuki Kobayshi†, Koji Aizawa (Kanazawa Inst. Tech.)
Copper precipitation process of thermally aged Fe-Cu alloys evaluated by EMAR method
Yasuhiro Kamada†, Shigehiko Chigusa1, Toshihiro Ohtani１, Hiroaki Kikuchi, Satoru Kobayashi(Iwate Univ.; １Shounan Inst. Tech.)Non-radiative investigation of photodecomposition of poly(di-hexyl silane) thin films by using the piezoelectric
photo-thermal spectroscopy
Atsuhiko Fukuyama†, Takahiro Kuroki, Kentaro Sakai１, Tomohisa Iwamoto, Shoji Furukawa, Tetsuo Ikari(Univ. Miyazaki; １Kyushu Ins. Tech.)Frequency characteristics of the polyurea ultrasonic variable-line-focus-beam-transducer
Takahiro Aoyagi†, Marie Nakazawa, Kentaro Nakamura (Tokyo Inst. Tech.)
Optical observation of Lamb wave in metal plate having a stepped thickness
Ryota Kudo†, Kazuhiko Imano (Akita Univ.)
Evaluation of acousto-optic effect in underwater ultrasonic pressure measurement
using an opticalinterferometer
Youichi Matsuda†, Masahiro Yoshioka, Tsuneo Kikuchi (NMIJ/AIST)
Abnormal frequency jump of quartz crystal microbalance in liquid
Sunhee Choi, Mikyung Lim†, Young.H. Kim (Korea Sci. Acad.)
Development of micro-LFB ultrasonic device
Jun-ichi Kushibiki, Yuji Ohashi, Mototaka Arakawa, Tomoya Tanaka, Sho Yoshida† (Tohoku Univ.)
Automatic measurement of nonlinearity parameter B/A for small volume liquid samples
Shigemi Saito†, Jung-Ho Kim１ (Tokai University; １GW Corporation)
Sensing grid for air temperature composed of asynchronous-type sound probe
Yosuke Katano†, Naoto Wakatsuki, Koichi Mizutani (Univ. Tsukuba)
Ultrasonic measurements of temperature distributions of the inside and surface of materials
Manabu Takahashi1†, Ikuo Ihara (Nagaoka Univ. Tech.)
Measurement of air humidity using ultrasonic delay line
Akihiko Kon†, Naoto Wakatsuki, Koichi Mizutani (Univ. Tsukuba)
Measurement of flow velocity in circular tube using a Fourier transform spectrometer
Tomoyuki Izumi†, Naoto Wakatsuki, Koichi Mizutani (Univ. Tsukuba)
Measurement of vertical temperature distribution using sound probe with reflectors
Ikumi Saito†, Koichi Mizutani, Naoto Wakatsuki, Satoshi Kawabe (Univ. Tsukuba)
Preconsolidation stress determination of clay by using ultrasonic waves
Hyung-Koo Yoon†, Joon Han Kim, Young-Uk Kim１, Jong-Sub Lee (Korea Univ.; １Myongji Univ.)
Nondestructive evaluation of compound weld defect by photoacoustic microscopy
Daijiroh Shiraishi†, Haruo Endoh, Tsutomu Hoshimiya (TohokuGakuin Univ.)
Relationship between photoacoustic spectra and thermoelectric properties of amorphous Si-Ge-Au thin film
Hiroaki Takiguchi†, Makoto Abe, Yoichi Okamoto, Hisashi Miyazaki, and Jun Morimoto (National Defence Acad.)

29

31
33

35
37
39
41
43
45
47
49

51

53
55

57
59
61
63
65
67
69
71
73
75
77
79

1P3-3*
1P3-4*
1P3-5
1P3-6
1P3-7*

1P3-8
1P3-9*
1P4-1*
1P4-2
1P4-3*
1P4-4
1P4-5*

1P4-6
1P4-7
1P4-8
1P4-9
1P4-10*

1P4-11
1P9-6

1P9-7

1P9-8

1P9-9
1P9-10
1P9-11*

1P5-1*

Detection and analysis of photothermal signal generated in capillary channel flow
Satoshi Hirashima†, Hitoshi Katae, Akira Harata (Univ. Kyushu)
Millisecond Brillouin scattering spectroscopy in solid and gas materials
Yasuo Minami†, Keiji Sakai (Univ. Tokyo)
Cladding-mode dependence of long-period fiber grating vibration sensor
Hiroyuki Somatomo†, Atsushi Wada, Satoshi Tanaka, Nobuaki Takahashi (National Defense Acad.)
Recognition of wavelength-multiplexed hierarchical label with acoustooptic waveguide circuit
Nobuo Goto1†, Yasumitsu Miyazaki１ (Univ. Tokushima; １Aichi Univ. Tech.)
Improvement of diffraction efficiency in surface-acoustic-wave-driven tandem acoustooptic frequency shifter
Susumu Shinkai†, Shoji Kakio, Yasuhiko Nakagawa, Takefumi Hara１, Hiromasa Ito１
(Univ. Yamanashi; １Tohoku Univ.)
Surface-acoustic-wave-driven acoustooptic modulator with wide wavelength range for visible laser light
Shoji Kakio†, Susumu Shinkai, Hiroyuki Kawate, Yasuhiko Nakagawa (Univ. Yamanashi)
Fabrication of magneto-optic thin films on LiTaO3 and/or LiNbO3 substrates by contact epitaxy
Hiroyuki Tashiro1†, Satoru Noge１, Takehiko Uno (Kanagawa Inst. Tech.;１Numazu Nation. College Tech.)
Propagation characteristics of substrates for lamb wave type elastic wave devices
Hitoshi Yoshida†, Yasuhiko Nakagawa, Shoji Kakio (Univ. of Yamanashi)
Matrix formulation for calculating spatial transfer characteristics in mechanical impedance mismatch system
Michio Ohki† (National Defense Acad.)
Characteristics of piezoelectric ceramic transducers tapered with exponential function
Jungsoon Kim1†, Moojoon Kim１, Kanglyeol Ha１ (Tongmyong Univ.; １Pukyong Univ.)
Analysis of Q-value of quartz crystal tuning fork using thermoelastic coupling equations
Hideaki Itoh†, Yuhya Tamaki（Shinshu Univ.）
Analytical study on load effects of LiNbO3 vibrator for ultrasonic motor using vibration mode coupling
Kyousuke Shibata†, Hideki Tamura, Manabu Aoyagi１1, Takehiro Takano２, Yoshiro Tomikawa, Seiji Hirose(Yamagata Univ.,１Muroran Inst. of Tech.,２Tohoku Inst. of Tech.)
A study on the shape of longitudinal bar resonators used as piezoelectric vibratory tactile sensors
Subaru Kudo† (Ishinomaki Senshu Univ.)
A study on sensitivity of frequency-change-type force sensor
Sumio Sugawara, Masaki Yamakawa†, Subaru Kudo (Ishinomaki Senshu Univ.)
Characterization of electrical probe for measuring induced charge on surface of piezoelectric vibrator
Shigetaka Kaga1† and Morio Onoe１ (Nihon Denpa Kogyo; １Univ. Tokyo)
Pure-shear mode BAW resonator consisting of (1120) textured AlN films
Takahiko Yanagitani†, Masato Kiuchi１ (Nagoya Inst. Tech.; １NMIJ/AIST)
Development of the ultrasonic information transmission system using one-chip microcomputer for wearable
devices
Shin-nosuke Suzuki1†, Manabu Ishihara, Yukio Kobayashi, Tamotsu Katane１, Osami Saito１,
Kazuto Kobayashi２ (Oyama N. C. T; １Chiba Univ.; ２Honda Electronics)
Mechanical transient analysis of breaking contact in a magnetic relay
Nobuo Takatsu†, Noboru Wakatsuki, Masahiro Oikawa (Ishimomaki Senshu Univ.)
Basic study on effect of current flow to time-reversal communication
Takuya Shimura†, Yoshitaka Watanabe, Hiroshi Ochi, Takehito Hattori１(JAMSTEC; １Nippon Marine Enterprises)
The effect of the number of receiving channels in wideband acoustic communication at deep sea
Hiroshi Ochi1†, Yoshitaka Watanabe, Takuya Shimura, Takehito Hattori１(JAMSTEC; １Nippon Marine Enterprises)
Temporal coherence variation for sea surface fluctuation
Jihyun Park, Jong R. Yoon†, Kyongbeak Ryu, Joung-Soo Park１(Pukyong National Univ.; １Agency Defense Development, Korea)
Numerical analysis of pulse wave propagated in Luzow-Holm Bay of Antarctic Ocean
Takenobu Tsuchiya, Mari Takahashi1†, Shuki Ushio１, Tetsuo Anada, Nobuyuki Endoh (Kanagawa Univ.; １NIPR)
Influence on sound field by number and interval of internal waves
Yoshiaki Tsurugaya1†, Toshiaki Kikuchi１, Koichi Mizutani２ (NEC; １National Defense Acad.; ２Univ. Tsukuba.)
Tidal effect of sound propagation at Hashirimizu Port
Hanako Ogasawara†, Toshiaki Nakamura, Kazuyoshi Mori, Koichi Mizutani１(National Defense Acad.; １Univ. Tsukuba)
SAW Development of small-sized SAW duplexer on SiO2/Al/LiNbO3 structure for Band IV system
Hidekazu Nakanishi†, Hiroyuki Nakamura, Tetsuya Tsurunari, Hiroki Kamiguchi, Yosuke Hamaoka, Rei Goto,
Yukio Iwasaki (Panasonic Electronic Devices)

81
83
85
87
89

91
93
95
97
99
101
103

105
107
109
111

113

115
117

119

121

123
125
127

129

1P5-2*
1P5-3*

1P5-4*
1P5-5
1P5-6*
1P5-7
1P5-8*
1P5-9*
1P5-10*
1P5-11

1P5-12
1P10-1
1P10-2*

1P10-3
1P10-4*
1P10-5*

1P10-6*

Improvement of shape factor of SAW resonator filter composed of SiO2/high-density-electrode/LiTaO3
Takaki Murata†, Michio Kadota, Takeshi Nakao, Kenji Matsuda (Murata Mfg.)
A full-wave analysis of surface Acoustic waves propagating on a SiO2 overlay/metal grating/rotated YX-LiNbO3
substrate structure
Yiliu Wang†, Ken-ya Hashimoto, Tatsuya Omori, Masatsune Yamaguchi (Chiba Univ.)
Interpolation technique for fast analysis of SAW and Lamb wave devices
Jan H. Kuypers†, Albert P. Pisano (Univ. California Berkeley)High frequency lamb wave device of LiNbO3 thin filmMichio Kadota, Takashi Ogami†, Kansho Yamamoto, Yasuhiro Negoro, Hikari Tochishita (Murata Mfg.)
A Basic study on face to face bonded SAW devices
Takanori Yamazaki†, Keishin Koh, Kohji Hohkawa (Kanagawa Inst. Tech.)Experimental study of SAW propagation characteristics under selectively deposited SiO2 on 128°YX-LiNbO3
Kumiko Konishi†, Akitoshi Omata, Tatsuya Omori, Ken-ya Hashimoto, Masatsune Yamaguchi (Chiba Univ.)
Leaky-SAW properties on reverse-proton-exchanged LiNbO3
Hidenori Shimizu†, Shoji Kakio, Yasuhiko Nakagawa (Univ. Yamanashi)
AlGaN/GaN device using buried electrode structure
Yuji Terao†, Satoshi Oshiyama, Keishin Koh, Kohji Hohkawa (Kanagawa Inst. Tech.)
Fabrication of highly oriented Ta2O5 piezoelectric thin films by RF-magnetron sputtering
Takeshi Mitsui†, Akinori Tsuchiya, Shoji Kakio, Yasuhiko Nakagawa (Univ. Yamanashi)
Variation of SAW velocity and propagation loss by grain boundaries
Shingo Chida†, Tomoaki Karaki, Masatoshi Adachi, Makoto Furuhata１, Takamitsu Higuchi１, Tsukasa Funasaka１(Toyama Prefectural Univ.; 2１SEIKO EPSON)
Speeding-up effects of aluminum oxide films on surface acoustic wave on cystalline quartz
Wen-Ching Shih, Tzyy-LongWang†, Yi-Ling Kuo (Tatung Univ.)
Research on photo-thermal signal of a scheffelera arboricola caused by Dye laser radiation
Yoshiaki Tokunaga, Masatoshi Yoshimura, Yukihiro Ishimaru†, Junji Hirama (Kanazawa Inst. Tech.)
Active ultrasonic SONAR system of bat: Relationship between 3-D flight path and acoustical characteristics ofecholocation sounds during foraging
Emyo Fujioka†, Shigeki Mantani, Shizuko Hiryu, Hiroshi Riquimaroux, Yoshiaki Watanabe (Doshisha Univ.)
Development of ultrasonic sensor for mobile robot to measure the normal direction and parallel of walls
Manabu Ishihara1†, Makoto Shiina, Shin-nosuke Suzuki1 (Oyama National College Tech.)
Target detection using multiple M-sequence signals in indoor environments
Hiroshi Matsuo†, Tadashi Yamaguchi, Hiroyuki Hachiya１ (Chiba Univ.; １Tokyo Inst. Tech.)
Design for high-accurate numerical simulation of acoustic field in time domain using finite difference time domain(FDTD) method and pseudospectral time domain (PSTD) method
Kan Okubo†, Masaki Omiya, Takao Tsuchiya１, Norio Tagawa (Tokyo Met. Univ.;１Doshisha Univ.)
Two dimensional simulation of nonlinear acoustic wave propagation using constrained interpolation profile (CIP)
methodMasahito Konno†, Kan Okubo, Takao Tuchiya１, Norio Tagawa1 (Tokyo Met. Univ.;１Doshisha Univ.)
16:00-17:15 Bulk wave devices / Surface wave devices

1J4-1
1J4-2*

1J5-1*

1J5-2
1J5-3

131

133
135
137
139
141
143
145
147
149

151
153

155
157
159

161

163

Chair: Jun Kondo (Shizuoka Univ.)

Shear mode type solidly mounted piezoelectric resonator using a LiTaO3 transducer
Takehiko Uno†, Kei Kasahara, Hiroyuki Tashiro (Kanagawa Inst. Tech.)
Monitoring of aggregation behavior of amyloid β peptide using wireless-electrodeless quartz-crystal
microbalance
Yuji Fukunishi1†, Kenichi Hatanaka, Hirotsugu Ogi1, Masahiko Hirao1, Masayoshi Nishiyama (Osaka Univ.)
Surface acoustic wave duplexer composed of SiO2/Cu-electrode/LiNbO3 structure having convex and concave
portions
Yasuharu Nakai†, Takeshi Nakao, Kenji Nishiyama, Michio Kadota (Murata Mfg.)
High frequency SAW resonator filter composed of ZnO/high-densityelectrode/quartz structureMichio Kadota, Takeshi Nakao, Kenji Matsuda, Takaki Murata† (Murata Mfg.)
Wideband DMS filter employing pitch modulated IDTs on Cu-grating/15°YX-LiNbO3-substrate structure
Takashi Miyamoto†, Tatsuya Omori, Ken-ya Hashimoto and Masatsune Yamaguchi (Chiba Univ.)

165

167

169
171
173

Wednesday, November 12
9:00- Registration
9:10-10:10 Aural English SessionⅠ
2E1*

2E2a
2E2b

2E2c

Chair: Keiji Sakai (Univ. Tokyo)

Elastic constant and microstructure of oxide thin films studied by picosecond laser ultrasounds
Tomohiro Shagawa†, Hirotsugu Ogi, Nobutomo Nakamura, Masahiko Hirao, Hidefumi Odaka１, Naoto Kihara１(Osaka Univ.; １Asahi Glass Co., LTD)High temperature integrated ultrasonic transducers for light-weight metal process monitoring
Makiko Kobayashi†, Cheng-Kuei Jen (National Research Council, Canada)
Imaging the acoustic rectification of surface acoustic waves
Sorasak Danworaphong†, Timothy A. Kelf, Osamu Matsuda, Oliver B. Wright, Kosei Ueno, Yoshiaki Nishijima,
Saulius Juodkazis, Hiroaki Misawa (Hokkaido Univ.)
Development of inspection equipment for bottom edges of rails with guided waves
Junjie Chang†, Takahiro Hayashi, Morimasa Murase, Keita Kataoka１ (Nagoya Inst. Tech.; １East Japan Railway)

175

177
179

181

10:10-10:15 Break
10:15-11:00 Aural English SessionⅡ
2E4*
2E5*
2E3*

Chair: Kentaro Nakamura (Tokyo Inst. Tech.)

Modeling of thermoelastic damping in piezoelectric aluminum nitride tuning forks
Gabriele Vigevani†, Jan H. Kuypers, Albert P. Pisano (Univ. California Berkeley)
Study on the frequency dependence of lateral energy leakage in RF baw device by laser probe system
Nan Wu†, Ken-ya Hashimoto, Keisuke Kashiwa, Tatsuya Omori, Masatsune Yamaguchi (Chiba Univ.)
Acousto-optic characteristics of silicon nanofoam
Takeshi Iino†, Kentaro Nakamura１ (P&I Lab.; １Tokyo Inst. Tech.)

183
185
187

11:00-11:05 Break
11:05-11:50 Aural English Session Ⅲ
2E6
2E8*

2E9*

Chair: Minoru Kurosawa (Tokyo Inst. Tech.)

The influence of liquid height on the ultrasonic power dissipated in organic solvents
Maricela Toma†, Satoshi Fukutomi, Yoshiyuki Asakura１, Shinobu Koda (Nagoya Univ.; １Honda Electronics)
Heat pump placed in the resonance tube connected to the loop-tube-type thermoacoustic cooling system
improves the cooling effectShin-ichi Sakamoto†, Hideo Yoshida１, Atsushi Sakaguchi１, Yoshiaki Watanabe１(Univ. Shiga Prefecture; １Doshisha Univ.)
A Study on SSBL underwater positioning using SS communication
Yoshitaka Watanabe†, Hiroshi Ochi, Takuya Shimura, Takehito Hattori (JAMSTEC; １NME)

189

191

193

11:50-13:00 Lunch
13:00-15:00 Poster Session
2P1-1*
2P1-2

2P1-3*

2P1-4
2P1-5*

Elastic properties of polymorphic protein crystals studied by micro-Brillouin scattering
Yuichiro Aoki†, Eiji Hashimoto, Hitoshi Kanazawa, Yuji Ike, Seiji Kojima (Univ. Tsukuba)
Elastic properties of potassium borate glasses in a wide composition range studied by Brillouin scattering
Mitsuru Kawashima†, Yu Matsuda, Yasuteru Fukawa, Seiichi Mamiya, Masao Kodama１, Seiji Kojima(Univ. Tsukuba;１SojoUniv. )Elastic constants of C12A7 single crystals studied by resonance ultrasound spectroscopy
Masataka Yamamoto†, Ryuichi Tarumi, Masahiko Hirao, Masahiro Hirano１, Sung Wng Kim１, Hideo Hosono１(Osaka Univ.; １Tokyo Inst. Tech.)
Ultrasonic study of h-BN machinable ceramic (Ⅲ)
Nobuo Kashiwagura†, Motoki Satoh, Mitsuo Yamaga, Masayuki Akita, Hiroaki Kamioka (Gifu Univ.)
Effect of polling process on property of hydrothermally synthesized PZT polycrystalline film
Shinya Irisawa†, Akito Endo１, Minoru Kurosawa２, Norimichi Kawashima, Shinichi Takeuchi(Toin Univ. Yokohama; １AIST; ２Tokyo Inst. Tech.)

195
197

199

201
203

2P1-6*

Shear wave velocity of vanishing materials
Q. Hung Truong†, Yong-Hun Eom, Changho Lee１, Jong-Sub Lee (Korea Univ.; １Georgia Inst. Tech.)
2P1-7*
Modulus change of rigid-soft mixtures during cementation
Changho Lee†, Q. Hung Truong１, Hyung-Koo Yoon１, Jong-Sub Lee１ (Georgia Inst. Tech.; １Korea Univ.)
2P2a-17* Accurate distance measurement by pulse compression using linear-period-modulated signals and calibration of
Doppler shift
Shinnosuke Hirata†, Minoru Kurosawa, Takashi Katagiri１ (Tokyo Inst. Tech.; １Sutekina)
2P2a-18 A study on liquid-level sensing by using trapped-energy-mode thickness vibrations
Ken Yamada†, Hisato Honda, Shuhei Horiuchi, Tetsuya Kinai (Tohoku Gakuin Univ.)
2P2a-19 Target ranging by using ultrasonic adaptive signal and pulse compression
Ryo Toh†, Dai Chimura, Seiichi Motooka (Chiba Inst. Tech.)
2P2a-20 A hydrogen sensor using ultrasonicYoshimine Kato† (Kyushu Univ.)
2P2a-21 More precise estimation of capacitance ratio in electromechanical coupling system
Michio Ohki† (National Defenese Acad.)
2P2a-22* Improvement of impulse response of loudspeaker based on equivalent circuit model
Syunji Inoue†, Naoto Wakatsuki, Koichi Mizutani (Univ. Tsukuba)
2P2b-10* Improvement of reflection point search by rectangular sound source through introducing array with small numberof element
Hiroyuki Masuyama1†, Koichi Mizutani１ (Toba Natl. Coll. Mar. Tech.; １Univ. of Tsukuba)
2P2b-11* Visualization of Lamb-type waves in glass plates using pulsed light source
Kojiro Nishimiya†, Koichi Mizutani, Naoto Wakatsuki, Takeshi Ohbuchi, Ken Yamamoto１(Univ. Tsukuba; １Kansai Univ.)
2P2b-12* Reconstruction of 3D sound field from 2D sound field using acoustical holography
Takeshi Ohbuchi†, Koichi Mizutani, Naoto Wakatsuki, Kojiro Nishimiya, Hiroyuki Masuyama１(Univ. Tsukuba;１Toba Natl. Coll. Mar. Tech.)
2P2b-13* Study on the extreme shallow underground imaging using SLDV
Touma Abe†, Tsuneyoshi Sugimoto (Toin Univ. Yokohama)
2P2b-14* Study on the ultrasonic imaging at the extreme shallow underground in submerged soil
Kunihiko Seo†, Takashi Shirakawa, Tsuneyoshi Sugimoto (Toin Univ. Yokohama)
2P2b-15* Resolution improvement of underground image using pulse compression
Hiraku, Kawasaki†, Tsuneyoshi Sugimoto (Toin Univ. Yokohama)
2P2b-16* Poisson’s ratio mapping system using immersion ultrasonic scanning
SeoYoung Oh†, Young H. Kim, Yosub Shin, Hyun-Joon Cho１
(Korea Sci. Acad.; １Advanced Inst. Quality and Safety)
2P2b-17 Development of an ultrasonic face classification system
Zhenwei Miao, Wei Ji, Yong Xu, Jun Yang† (Chinese Acad. Sci.)
2P2c-6* Development of a movable inspection sensor for a pipe using an EMAT
Yusuke Okawa†, Riichi Murayama, Hideaki Morooka, Yusuke Yamashita (Fukuoka Inst. Tech.)
2P2c-7Development of circumferential scan in pipes by non contact air coupled ultrasonic testing
Masakazu Takahashi†, Hidekazu hoshino, Yukio Ogura, Hideaki Kitagawa１, Junichi Kusumoto１, Akihiro Kanaya１,
Hideo Nishino２ (Japan Probe; １Kyushu Electric Power; ２Univ. Tokushima )2P2c-8Nonlinear acoustic evaluation of creep damage in a Cr-Mo-V steel
Toshihiro Ohtani† (Shonan Inst. Tech.)
2P2c-9* Nonlinear ultrasonic characterization of thermally damaged Westerly granite
Claude Inserra†, Shiro Biwa, Youqing Chen (Kyoto University)
2P2c-10 Optimal time reversal focusing of random array using an iterative least squares pre-filtering method
Dengyong Ma, Jun Yang† (Chinese Acad. Sci.)
2P5-13
Study of SAW excitation efficiency for novel gas sensor installed in “Sensor Network”
Y.Hiraizumi†, H.Aoki, T.Watanabe, J.Matsuda, M.Hikita (Kogakuin University)
2P5-14* Ball SAW gas chromatograph system for analysis of mixed volatile organic compounds
Yutaro Yamamoto†, Shingo Akao, Masanori Sakuma, Kentaro Kobari, Kazuhiro Noguchi１, Noritaka Nakaso,
Toshihiro Tsuji, Kazushi Yamanaka (Tohoku Univ.; １TOPPAN Print.)
2P5-15Development of orientation controlled ball surface acoustic wave device with optimal IDT position and analysis ofpropagation characteristics
Takayuki Yanagisawa†, Tsuneo Ohgi, Noritaka Nakaso, Kazushi Yamanaka１ (TOPPAN Print.; １Tohoku Univ.)
2P5-16* Fabrication of thin sensitive film of ball SAW sensor using off-axis spin coating method
Kentaro Kobari†, Yutaro Yamamoto, Masanori Sakuma, Shingo Akao１, Toshihiro Tsuji1, Kazushi Yamanaka(Tohoku Univ.; １TOPPAN Print.)

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2P5-17Development of odor display device using surface acoustic wave
Taro Monji†, Atsushi Saitoh, Toru Nomura (Shibaura Inst. Tech.)
2P5-18* Micro-Laboratory on SAW piezoelectric crystal
Noriyuki Yasuda†, Mitsunori Sugimoto, Jun Kondoh (Shizuoka Univ.)
2P5-19* Measurements of standard viscosity liquid using shear horizontal surface acoustic wave sensor
Takeshi Morita†, Mitsunori Sugimoto, Jun Kondoh (Shizuoka Univ.)
2P6-1
Numerical simulations of acoustic cavitation noise with temporal variation of the number of bubbles
Kyuichi Yasui†, Toru Tuziuti, Judy Lee, Teruyuki Kozuka, Atsuya Towata, Yasuo Iida (AIST)
2P6-2*
Dependence of sonochemiluminescence on pulsed-wave conditions at 1 MHz
Ayako Ozawa†, Pak-Kon Choi (Meiji Univ.)
2P6-3
Spatio-temporal separation of Na-atom emission and continuum in sonoluminescence
Pak-Kon Choi†, Shogo Abe (Meiji Univ.)
2P6-4*
Influence of the secondary acoustic radiation from a bubble on the vibration phase of the other bubble
Takaaki Fujikawa†, Kenji Yoshida, Yoshiaki Watanabe (Doshisha Univ.)
2P6-5*
Collapsing behaviors of two bubbles adhered to the rigid wall in an ultrasonic field: Simultaneous generation of
micro flows
Kenji Yoshida1†, Yoshiaki Watanabe (Doshisha Univ.)
2P6-6
FEM Analysis of piezoelectric resonance characteristics on the geometrical configuration of a sonochemical
reactorNagaya Okada1†, Masanori Sato, Yoshiyuki Asakura (Honda Electronics)
2P6-7
The intensity of MBSL in aqueous solutions at 2.4 MHz
Hisashi Harada†, Naohiro Iwata, Keisuke Shiratori (Meisei Univ.)
2P7a-14 Basic investigation for detection of early cancer by optically assisted ultrasonic velocity change imaging
Hiromichi Horinaka†, Syunsuke Kawakami, Satoshi Ishibashi, Tetsuya Matsuyami, Kenji Wada,
Toshiyuki Matsunaka (Osaka Prefecture Univ.)
2P7a-15* Small calculi detection for medical acoustic imaging with correlation between ultrasonic echo signals
Hirofumi Taki†, Tetsuya Matsuda, Toru Sato (Kyoto Univ.)
2P7a-16* Experimental study of high-resolution ultrasonic imaging for multiple target detection with frequency domaininterferometry
Tomoki Kimura†, Hirofumi Taki, Takuya Sakamoto, Toru Sato (Kyoto Univ.)
2P7a-17* Beamformer design to shield noise sources
Mariko Yamamoto†, Shin-ichiro Umemura１, Takashi Azuma (Hitachi; １Tohoku Univ.)
2P7a-18 Optimum quadratic filters for nonlinear ultrasonic imaging
Pornchai Phukpattaranont†, Chusak Limsakul (Prince Songkla Univ.)
2P7a-19 Tissue boundary imaging based on eigenvalue decomposition
Hironari Masui1†, Takashi Azuma, Kazuaki Sasaki１ (Hitachi; １Tokyo Univ. A&T)
2P7a-20 Reconstruction of shear modulus with mechanical source
Chikayoshi Sumi†, Sayaka Suekane (Sophia Univ.)
2P7b-1* Characterization of ultrasound generated protein microbubbles: from production to destruction
Judy Lee†, Atsuya Towata, Kyuichi Yasui, Teruyuki Kozuka, Toru Tuziuti, Yasuo Iida (AIST)
2P7b-2
Study of effect in active path selection of fluid microcapsules to the variation of ultrasound emission at thebifurcation point
Yusuke Muramatsu†, Sawami Ueda, Ryusuke Nakamoto, Yusuke Nakayashiki, Kohji Masuda, Ken Ishihara１(Tokyo Univ. A&T; １Ehime Univ.)
2P7b-3* Bi-frequency driven transducers for multi-frequency ultrasonic imaging
Natsuki Yoshizumi1†, Shigemi Saito１, Daisuke Koyama２, Kentaro Nakamura２, Iwaki Akiyama1 (Shonan Inst.
Tech.; １Tokai Univ.; ２Tokyo Inst.Tech.)
2P7b-4High-amplitude and long-burst pulse transmission array probe for phase-conversion molecular imaging
Takashi Azuma†, Shiho Sonoda, Ken-ichi Kawabata, Shin-ichiro Umemura１ (Hitachi; １Tohoku Univ.)
2P7b-5* Comparison of sound pressure distribution analysis with scale up experiment for small ultrasonic acoustic lens
probe
Fumitaka Naitou1†, Sayuri Matsumoto１, Mari Takahashi, Takenobu Tsuchiya, Nobuyuki Endoh(Kanagawa Univ.; １PARI)
2P7b-6* Effect of edge mode resonance on directivity of small ultrasound probe fabricated with Lead Zirconate Titanate
polycrystalline film deposited by hydrothermal method
Tomohito Hasegawa†, Minoru Kurosawa , Shinichi Takeuchi１ (Tokyo Inst. Tech.; １Toin Univ. Yokohama)
2P7b-7
Mechanical properties of low attenuation silicone rubber acoustic lens material doped with zinc oxide for medicalecho probe
Noriko Yamamoto1†, Yohachi Yamashita１, Kazuhiro Itsumi (Toshiba; １Toshiba Research Consulting)

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2P8-1*
2P8-2*

2P8-3

2P8-4*

2P8-5

2P8-6*
2P8-7*
2P8-8*

2P8-9

2P8-10*

2P9-1

2P9-2

2P9-3

2P9-4
2P9-5*

2P10-7

2P10-8*

2P10-9*A novel cleaning equipment using ultrasonic waveguide mode
Kazunari Suzuki1†, Ki Han, Shoichi Okano, Jyunichiro Soejima, Yoshikazu Koike (KAIJO; １Shibaura Inst. Tech.)
Nucleation enhancement of al alloys by high intensity ultrasoundJeong IL Youn1†, Byoung IL Kang, Beom Suk Han１, Young Jig Kim(Sungkyunkwan Univ.; １Korea Automotive Tech.)
Ultrasonically induced enhancement in treatment of livestock waste sludge
Jiho Park, Young Uk Kim†, Jong-Sub Lee１, Mian Chen Wang２(Myongji Univ.; １Korea Univ.; ２Pennsylvania State Univ.)
Estimation of sound energy distribution for the design optimization of large-scale sonoreactors
Younggyu Son1†, Myunghee Lim, Ik-Beom Park１, Mingcan Cui1, Jeehyeong Khim
(Korea Univ.; １Gyeonggi-do Instit. Health Environment)
Extraction of metal species from contaminated soils utilizing supercritical CO2 and ultrasoundIk B. Park†, Younggyu Son, Il S. Song１, Kyung H. Na１, Jongchan Kim１, Jeehyeong Khim
(Korea Univ.; １Gyeonggi-do Instit. Health Environment)
Optimization of ultrasound irradiation for the soil washing of diesel-contaminated fine particles
Beomguk Park†, Jihoon Cha, Younggyu Son, Myunghee Lim, Jeehyeong Khim (Korea Univ.)
Compaction of soft magnetic composite powder using ultrasonic vibrations
Shinichi Kikuchi1†, Daisuke Koyama, Kentaro Nakamura, Hyun-Lok Cha１ (Tokyo Inst. Tech.; １KITECH)
Comparison of magnetic properties of SMC motor core fabricated by ultrasonic vibration compaction
Hyun Rok Cha†, Shinichi Kikuchi１, Seoung Kyu Jeon, Sung Ho Lee, Cheol Ho Yun１, Kentaro Nakamura１(KITECH.; １Tokyo Inst. Tech.)Room-temperature ultrasonic bonding of semiconductor thin-dies with die attach films on glass substrates
Siu Wing Or†, Sui Yin Wong, Ho Chi Wong, Yiu Ming Cheung１, Ping Kong Choy１(Hong Kong Polytech. Univ.; １ASM Assembly Automation)
Design of ultrasonic horn for microelectronic parts: material dependence
Minseok Bae†, Young H. Kim, Jeong-Hoon Moon１, Kyung-soo Kim２
(Korea Sci. Acad.; １Suwon Sci. Coll.; ２Changjo Eng.)
Precision measurement of convergence characteristic of single aspheric acoustic lens
Sayuri Matsumoto, Yuichi Shin†１, Fumitaka Naito１, Takenobu Tsuchiya１, Nobuyuki Endoh１, Hidenori Takeyama２(PARI; １Univ. Kanagawa; ２Genesia)
Sound pressure field focused by aplanatic acoustic lens for ambient noise imaging
Kazuyoshi Mori†, Hanako Ogasawara, Toshiaki Nakamura, Yuji Sato１, TakenobuTsuchiya２,
Nobuyuki Endoh２ (National Defense Acad.; １Univ. Tsukuba; ２Kanagawa Univ.)
FEM Analysis of low frequency and wideband array composed of disk bender transducers having differential
connections
Mitsuru Yamamoto†, Takeshi Inoue, Hiroshi Shiba, Yuta Kitamura (NEC)Optimal design of a barrel stave flextensional transducer
Hoeyong Kim, Yongrae Roh† (Kyungpook National Univ.)
Analysis of the effect of reflected wave from sonar-dome on radiation impedance for cylindrical array
Jungsoon Kim†, Moojoon Kim１, Kanglyeol Ha１, Heeseon Seo２, Cheeyoung Joh２
(Tongmyong Univ.; １Pukyong Univ.; ２Agency Defense Development)
Numerical simulation of sound field in time domain using a combination of FDTD method and boundary integral
equation method
Takao Tsuchiya, Atsushi Kumagai (Doshisha Univ.)
Phase shift keying modulation with impulse response for ultrasonic communication
Tadashi Ebihara†, Keiichi Mizutani１, Naoto Wakatsuiki, Koichi Mizutani, Koichi Morikawa(Univ. Tsukuba; １Tokyo Inst. Tech.)
Locality of area coverage on acoustic communication in air using differential phase shift keying
Keiichi Mizutani†, Tadashi Ebihara１, Naoto Wakatsuki１, Koichi Mizutani１ (Tokyo Inst. Tech.; １Univ. Tsukuba)

15:00-15:50 Invited LectureⅠ
2INV1

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Chair: Kazushi Yamanaka (Tohoku Univ.)

High temperature ultrasonic probes and their potential applications
Cheng-Kuei Jen†, Makiko Kobayashi (National Research Council, Canada)339

15:50-16:40 Invited LlectureⅡ
2INV2Chair: Shin-ichiro Umemura (Tohoku Univ.)

Bubbles and ultrasound: A new partnership for medical imaging

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Peter N. Burns† (University of Toronto)

16:40-16:45 Break
16:45-17:15 Aural English Session Ⅳ
2E7a
2E7b

Chair: Mami Matsukawa (Doshisha Univ.)

Separation of nonlinear ultrasound signals based on second-order volterra system identification
Pornchai Phukpattaranont† (Prince Songkla Univ.)
Bone microelastic properties assessed by scanning acoustic microscopy : a face-to-face comparison withnanoindentation
Pascal Laugier†, Fabienne Rupin, Davy Dalmas１, Francoise Peyrin２, Kay Raum３, Etienne Barthel１, Amena Said
(Univ. Paris 06; １Unite Mixte CNRS/Saint-Gobain; ２CNRS; ３Martin Luther Univ. Halle-Wittenberg)

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17:15-17:30 Award Ceremony
17:45-

Reception

Thursday, November 13
9:00-

Registration

9:10-10:10 Imaging methods / Nondestructive testing
3J2b-1*3J2b-23J2c-13J2c-2*Chair: Hirotsugu Ogi (Osaka Univ.)

Development of ultraviolet-excitation photothermal microscope and observation of non-stained biological cells
Noriyuki Fujii†, Akira Harata (Kyushu Univ.)
Imaging of electromagnetic properties via ultrasound waves
Kenji Ikushima†, Hiraku Toida１, Susumu Komiyama１ (Tokyo Univ. A&T; １Univ. Tokyo)
Ultrasonic measurement of closed stress corrosion crack depth using subharmonic phased array
Yoshikazu Ohara†, Hiroaki Endo, Tsuyoshi Mihara１, Kazushi Yamanaka (Tohoku Univ.; １Univ. Toyama)
A detection of nonlinear components of Lamb wave generated from closed cracks using double-layered
piezoelectric transducer
Makoto Fukuda†, Kazuhiko Imano (Akita Univ.)

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10:10-10:15 Break
10:15-10:45 Sonochemistry
3J6-1
3J6-2

Chair: Tatsuro Matsuoka (Nagoya Univ.)

Observation of bubble population phenomena in sonochemical reactor
Yasuo Iida†, Atsuya Towata, Kyuichi Yasui, Teruyuki Kozuka, Toru Tuziuti, Judy Lee (AIST)
Effects of ultrasound exposure time on dispersion of nanometer-sized diamond particles
Takeyoshi Uchida†, Tsuneo Kikuchi, Takahiro Aoki１, Norimichi Kawashima１, Shinichi Takeuchi１(AIST; １Toin Univ. Yokohama)

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10:45-10:50 Break
10:50-11:50 High power ultrasound
3J8-1

3J8-2

Chair: Subaru Kudo (Ishinomaki Senshu Univ.)

High speed and quick response precise linear stage system using V-shape transducer ultrasonic motors
Kazumasa Asumi†, Ryouichi Fukunaga,Takeshi Fujimura, Minoru Kuribayashi Kurosawa１(Taiheiyo-Cement; １Tokyo Inst. Tech.)
Application of a novel cleaning equipment using ultrasonic waveguide mode to the post CMP cleaning: Cleaning
efficiency of spot type shower
Kazunari Suzuki, Ki Han†, Shoichi Okano, Jyunichiro Soejima Yoshikazu Koike１

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3J8-4*(KAIJO; １Shibaura Inst.of Tech.)
Properties of lead-free piezoelectric ceramics and its application to ultrasonic cleaner
Tonshaku Tou†, Yuki Hamaguti, Yuichi Maida, Haruo Yamamori, Kazutoshi Takahashi１,
Yoshimitsu Terashima１ (Honda Electronics; １Fuji Titanium Industry)
Acoustic characteristics of high frequency ultrasound probe using piezoelectric film deposited by aerosol
deposition method
Akito Endo†, Jun Akedo (AIST )

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365

11:50-13:00 Lunch
13:00-15:00 Poster Session
3P2b-1
3P2b-2*3P2b-3
3P2b-4:

3P2b-5
3P2b-6

3P2b-7:

3P2b-83P2b-9*3P2c-1*3P2c-2*3P2c-3*3P2c-43P2c-5
3P6-8*
3P6-9*
3P6-10
3P6-11*
3P6-12*

3P6-13*Visualization of the wavefronts of ultrasound passed through bovine bones
Masahiro Ohno† (Chiba Inst. Tech.)Phantom evaluation experiment of ultrasound CT for visceral fat measurement
Koichiro Kawamoto†, Akira Yamada, Miki Tamura (Tokyo Univ. A&T)
Quadrangular view ultrasound inverse scattering computed tomography
Akira Yamada† (Tokyo Univ. A&T)
Improvement of vibrational distribution measurement of piezoelectric devices based on image processings
Kentaro Tachibana†, Yasuaki Watanabe, Noriyuki Imaeda, Shigeyoshi Goka, Takayuki Sato, Hitoshi Sekimoto(Tokyo Metropolitan Univ.)
Visualization of elastic waves by photorefractive imaging method
Takahiro Miura†, Makoto Ochiai, Yoshikazu Ohara１, Kazushi Yamanaka１ (Toshiba; １Tohoku Univ.)
Imaging of surface acoustic wave reflection and focusing using circular, ellipsoidal and parabolic boundaries
Motonobu Tomoda†, Oliver B. Wright, Kosei Ueno, Yoshiaki Nishijima, Saulius Juodkazis, Hiroaki Misawa(Hokkaido Univ.)
Real-time imaging of GHz acoustic waves on bulk acoustic resonators
Takashi Fujikura†, Osamu Matsuda, Oliver B. Wright, Jeremy Masson１, Sylvain Ballandras１(Hokkaido Univ.; １FEMTO-ST)
Real time imaging and dispersion behavior of Lamb waves in an elastic wedge
Shinnosuke Matsueda†, Motonobu Tomoda, Osamu Matsuda, Oliver B. Wright (Hokkaido Univ.)
Temperature distribution measurement in rectangular space by acoustic computerized tomography using
projection data of unequal angular intervals
Ayumu Minamide†, Koichi Mizutani, Naoto Wakatsuki (Univ. Tsukuba)
Piezoelectric oscillator sensor to detect damages in a structure
Hyeoksang Kwon†, Byungsoo Kim, Yongrae (Kyungpook National Univ.)
Investigation on the reflection and transmission of Lamb waves across a rectangular crack
Byungsoo Kim†, Hyeoksang Kwon, Yongrae (Kyungpook National Univ.)
Acoustical detection of internal cracks of square billets
Hideto Mitsui†, Koichi Mizutani, Naoto Wakatsuki, Masaki Yamano１ (Univ. Tsukuba; １Sumitomo Metal)
Visualization and modal analysis of guided waves from a defect in a pipe
Nor Salim Bin Muhammad†, Takahiro Hayashi, Morimasa Murase, Shoji Kamiya (Nagoya Inst. Tech.)
Defect detections of pipes using guided waves generated by an efficient transduction method with a reflector
Hideo Nishino†, Keiji Ogura, Kenichi Yoshida (The Univ. Tokushima)
Biodiesel production from virgin and waste oils using ultrasonic reactor in pilot scale
Le Tu Thanh†, Kenji Okitsu, Yasuhiro Sadanaga, Norimichi Takenaka, Hiroshi Bandow (Osaka Prefecture Univ.)
Ultrasonic soil washing with surfactants for the remediation of diesel-contaminated soil
Jihoon Cha†, Beomguk Park, Younggyu Son, Mingcan Cui, Jeehyeong Khim (Korea Univ.)
Relationship between the lactic fermentation promoted by ultrasound and the fermentation temperature
Satoshi Koyama†,Nobuyoshi Masuzawa (Musashi Inst. Tech.)Enhancement in removal efficiency of tannins in livestock wastewater using ultrasound/ozone
Junghyun Lim†, Eunju Cho, Mingcan Cui, Myunghee Lim, Jeehyeong Khim (Korea Univ.)
The effect of sonication on chlorine disinfection in the inactivation of E.coli
Hoang Lam Pham†, Hyunjun Kim, Myunghee Lim, Iordache Ioan１, Jeehyeong Khim
(Korea Univ.; １Nat. Res. Development Inst., Romania)
The effects of power density and irradiation time for ultrasonic inactivation of E. coli
Hyunjun Kim†, Hoang Lam Pham, Myunghee Lim, Mingcan Cui, David Elena１, Jeehyeong Khim
(Korea Univ., １Nat. Res. Development Inst., Romania)

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3P6-14*

Biodegradability enhancement in ultrasound-assisted oxidation for the removal of dye
Eunju Cho†, Junghyun Lim, Mingcan Cui, Younggyu Son, Jeehyeong Khim (Korea Univ.)
3P6-15* Physicochemical elucidation of cavitation bubble interfacial region
Ben Nanzai†, Kenji Okitsu, Norimichi Takenaka, Hiroshi Bandow (Osaka Prefecture Univ.)
3P6-16* Sonochemical degradation of phenol and cyclohexanol in mixed solution
Kenta Ishikawa†, Ben Nanzai, Kenji Okitsu, Norimichi Takenaka, Hiroshi Bandow (Osaka Prefecture Univ.)
3P6-17* Sonolysis of dicarboxylic acids in aqueous solution
Rei Moriya†, Yukio Naruke, Hisashi Tanaka, Hisashi Harada (Meisei Univ.)
3P6-18
Effect of agitation condition on performance of sonochemical reaction
Keiji Yasuda†, Kazumasa Matsuura, Hirotoshi Horizoe (Nagoya Univ.)
3P6-19* Effect of hydrogen peroxide and frequency on sonochemical degradation of phenol
Myunghee Lim†, Younggyu Son, Mingcan Cui, Jeehyeong Khim (Korea Univ.)
3P6-20Effects of gas content in a liquid on the threshold for free radical production
Kengo Okada†, Nobuki Kudo, Mariame A. Hassan１, Takashi Kondo１, Katsuyuki Yamamoto(Hokkaido Univ.; １Univ. Toyama)
3P7a-1
Improvement of tissue strain uniformity and elastogram by compression optimizing
Shizuka Sato†, Takayuki Sato, Sayuki Aiura, Yasuaki Watanabe, Shigeyoshi Goka, Hitoshi Sekimoto(Tokyo Metropolitan Univ.)
3P7a-2
Optimization of apodization function for lateral modulation
Chikayoshi Sumi†, Yuuichi Komiya, Shinya Uga (Sophia Univ.)
3P7a-3* Lateral modulation and displacement vector measurement using hyperbolic scan by virtual beam forming
Kengo Kondo†, Makoto Yamakawa１, Tsuyoshi Shiina１ (Univ. Tsukuba; １Kyoto Univ.)
3P7a-4* Experimental evaluation of high-speed 2D motion vector measurement by combining synthetic aperture arrayprocessing with constrained least squares method
Ryouta Yokoyama†, Shin-ichi Yagi, Kiyoshi Tamura１, Masakazu Sato２ (Meisei Univ.; １Aloka; ２Microsonic)
3P7a-5* Elastography using graph cuts
Naoto Akazawa†, Kan Okubo, Norio Tagawa (Tokyo Metropolitan Univ.)
3P7a-6
Precise tissue elasticity reconstruction based on detection of small displacements
Sayuki Aiura†, Takayuki Sato, Shizuka Sato, Yasuaki Watanabe, Hitoshi Sekimoto (Tokyo Metropolitan Univ.)
3P7a-7* Development of ultrasound breast imaging system
Satoshi Ozawa†, Hokuma Saito１,Masakazu Sato２, Hiroshi Kitunai２, Takasuke Irie２, Masasumi Yoshizawa１,
Kan Okubo, Norio Tagawa, Hiromu Yokoi３, Nobuyuki Honda４ (Tokyo Metropolitan Univ.;
１
Tokyo Metropolitan Coll.; ２Microsonic; ３Yokoi Orthopedic Clinic; ４Teramoto Memorial Hospital)
3P7a-8
Evaluation of preprocessing operations for the extraction of fine blood vessels from ultrasound images
Yasuaki Osawa†, Masayasu Ito (Tokyo Denki Univ.)
3P7a-9* Visualization of intersection points of motion vectors in left ventricle by processing successive echograms
Rui Takahashi†, Kohji Masuda, Takashi Yoshinaga, Hirotaka Matsuura, Shun Uchibori (Tokyo Univ. A&T )3P7a-10 Application of independent component analysis to speckle reduction in liver echo image
Tadashi Yamaguchi1†, Hiroki Suyari (Chiba Univ.)
3P7a-11 Influence of blood vessel wall motion on shear rate estimation in blood flow
Naotaka Nitta† (AIST)
3P7a-12 Accuracy evaluation for high-frequency ultrasonic measurement of viscoelasticity of radial arterial wall by basic
experiments
Kazuki Ikeshita†, Hideyuki Hasegawa, Hiroshi Kanai (Tohoku Univ.)
3P7a-13 Optimization of window size and search region in 2D correlation function for assessment of regional myocardial
contraction and relaxation
Yasunori Honjo†, Hideyuki Hasegawa, Hiroshi Kanai (Tohoku Univ.)
3P7b-8* Problems in deriving the soft-tissue thermal index(TIS) using ISPTA in the near field
Masahiro Yoshioka† (AIST)
3P7b-9* Basic verification of the tissue effect of an ultrasonically activated scalpel
Masaru Oya†, Tadashi Yamaguchi, Hideki Hayashi, Hiroyuki Hachiya１ (Chiba Univ.;１Tokyo Inst. Tech.)
3P7b-10 Development of area image sensing method for puncture needle type ultrasonography
Masasumi Yoshizawa†, Ryuuji Emoto, Hirotaka Kawabata, Takasuke Irie, Kouichi Itoh２, Tadashi Moriya３(Tokyo MetropolitanColl.; １Microsonic; ２Hitachi-Omiya Saiseikai Hospital; ３Tokyo Metropolitan Univ.)
3P7b-11* Inline transmitter/receiver system without direct receiving of transmitted signals
Masayuki Tanabe†, Kan Okubo and Norio Tagawa (Tokyo Metropolitan Univ.)
3P7b-12* Matching layer function of PVDF receiver in inline transmitter/receiver system
Makoto Miyata†, Masayuki Tanabe, Kan Okubo and Norio Tagawa (Tokyo Metropolitan Univ.)

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3P7b-13* Three-dimensional scatterer-size estimation in dissected human lymph nodes using high-frequency ultrasoundJonathan Mamou†, Alain Coron１, Masaki Hata２, Junji Machi２, Eugene Yanagihara２, Pascal Laugier１,
Ernest J. Feleppa (Riverside Research Inst.; １UPMC Univ. Paris 06; ２Univ. Hawaii)
3P7b-14* Frequency dependence of ultrasonic properties of bovine cortical bone samples
Guillaume Haïat†, Magali Sasso１, Salah Naili１, Mami Matsukawa２(Univ. Paris 7 ; １Univ. Paris 12; ２Doshisha Univ.)
3P7b-15* Influence of multiple scattering and of absorption on velocity dispersion in trabecular bone
Guillaume Haïat†, Alain Lhémery１, Frédéric Padilla２, Pascal Laugier２, Salah Naili３(Univ. Paris 7; １Commissariat à l’énergie Atomique; ２Univ. Paris 6; ３Univ. Paris 12)
3P7b-16 Estimation of in vivo cancellous bone elasticity
Takahiko Otani†, Isao Mano１, Toshiyuki Tsujimoto２, Tadahito Yamamoto4, Ryota Teshima３, and Hiroshi Naka４(Doshisha Univ.; １OYO Electric; ２Horiba; ３Tottori Univ.; ４Osaka City Univ.)
3P7b-17* Anisotropy of longitudinal ultrasound velocity and HAp orientation in bovine cortical bone
Yuichiro Yaoi†, Kazufumi Yamamoto１, Takahiko Yanagitani２, Mami Matsukawa, Kaoru Yamazaki１,
Akira Nagano１ (Doshisha Univ.; １Hamamatsu Univ. Sch. Med. ; ２Nagoya Inst. Tech.)
3P7b-18 The effect of soft tissue on the ultrasonic wave propagation in cancellous bone
Takashi Saeki†, Tomohiro Kubo, Mami Matsukawa, Yoshiki Nagatani１ (Doshisha Univ.; １Kobe City Coll. Tech.)
3P7b-19 Influence of trabecular elements on fast and slow wave propagations in oblique directions to layers of a stratifiedtrabecular phantom
Atsushi Hosokawa† (Akashi Coll. Tech.)
3P7b-20* Introduction of “Digital elastic model of human body” for 3-D FDTD simulation: Elastic wave propagation inhuman body
Yoshiki Nagatani†, Atsushi Hosokawa１, Takefumi Sakaguchi２, Mami Matsukawa３, Yoshiaki Watanabe３(Kobe City Coll. Tech.; １Akashi Colle. Tech.; ２Nara Medical Univ.; ３Doshisha Univ.)
3P8-11
A Study on structure of joined surfaces on ultrasonic joining of Au by use of surface acoustic wave device
Kengo Naruse†, Kiyomi Mori１, Yuji Watanabe１ (Seidensha Electronics; １Takushoku Univ.)
3P8-12
Study on the sound source and the reflector to generate strong acoustic field for levitation
Teruyuki Kozuka†, Kyuichi Yasui, Toru Tuziuti, Judy Lee, Atsuya Towata, Yasuo Iida (AIST)
3P8-13
Aerial ultrasonic source using stripe-mode transverse vibrating plate with jutting driving point
Hikaru Miura , Hitoshi Ishikawa† (Nihon Univ.)
3P8-14
Examination of method for judging heat receiving of mortar by using aerial ultrasonic waves having finite
amplitudes
Youichi Ito, Naoto Asakura† (Nihon Univ.)
3P8-15
Linearly convergent type aerial ultrasonic source with changeable incidence angle of sound waves and its
high-intensity sound field.
Youichi Ito† (Nihon Univ.)
3P8-16* Applying diverging tube for the low temperature drive on the loop-tube type thermoacoustic system
Takahiro Ishino†, Shin-ichi Sakamoto１, Masahiro Nishikawa, Yoshiaki Watanabe(Doshisha Univ.; １Univ. Shiga Pref.)3P8-17* Effect of lamination mesh on energy conversion from sound to heat in thermoacoustic system
Atsushi Sakaguchi†, Shin-ichi Sakamoto１, Tsuji Yoshiyuki, Yoshiaki Watanabe(Doshisha Univ.; １Univ. of Shiga Pref.)3P8-18* The effect of membrane insert position on the acoustic field in a thermoacoustic system
Masahiro Nishikawa†, Shin-ichi Sakamoto１, Takahiro Ishino, Yoshiaki Watanabe(Doshisha Univ.; １Univ. of Shiga Pref.)3P8-19* Rotation phase analysis of surface particle motion of coiled waveguide for flexural ultrasound wave
Ryo Tanaka†, Masayuki Tanabe, Kohei Tomoda, Kan Okubo, Norio Tagawa (Tokyo Metropolitan Univ.)
3P8-20* Development of precise rotation manipulator of a ball based on resonant vibration of cantilever
Teruyuki Tomita†, Toshihiro Tsuji, Kazushi Yamanaka (Tohoku Univ.)
3P8-21* Loudspeaker by ultrasonic motors and it’s control system
Yusuke Masuda†, Keigo Higashida, Syunsuke Chiba, Hirokazu Negishi１, Juro Ohga１, Kazuaki Maeda２,
Hajime Kubota (Chiba Inst. Tech.; １MIX Acous. Lab; ２TOA.)
3P8-22
Evaluating the efficacy of counterweight structure in improving the performance of linear ultrasonic motors
Chaodong Li†, Jian Jin (Shanghai University)
3P8-23
Preload control of high-speed ultrasonic actuator and equivalent circuit analysis
Manabu Aoyagi†, Maiko Seki１, Takehiro Takano１, Hideki Tamura２, Yoshiro Tomikawa２(Muroran Inst. Tech.; １Tohoku Inst. Tech.; ２Yamagata Univ.)

457

459

461

463

465

467

469

471

473
475
477

479

481
483

485

487

489
491
493

495
497

3P8-24*

3P8-25*
3P8-26
3P8-273P8-28A new type rectangular plate type linear ultrasonic motor using a double mode piezoelectric vibrator of the firstlongitudinal mode and the first flexural mode
Ryouichi Fukunaga†, Kazumasa Asumi, Ryouta Asakura, Yutaka Inada (Taiheiyo Cement)
Elastic holding mechanism for ultrasonic motors
Naotake Inoue†, Takaaki Ishii (Univ. Yamanashi)
Design of a two-dimensional array of multi-degree-of-freedom ultrasonic micro motors
Yasuyuki Goda†, Daisuke Koyama, Kentaro Nakamura (Tokyo Inst. Tech.)
A self-running ultrasonically levitated 2D stage
Daisuke Koyama†, Kentaro Nakamura (Tokyo Inst. Tech.)
Effects of gap distance on revolution speed of non-contact type ultrasonic motor using flexurally vibrating disk
Yasuhiro Yamayoshi†, Tomohiro Nakagawa, Hideki Tamura, Seiji Hirose (Yamagata Univ.)
15:00-16:00 Medical imaging

3J7a-1*
3J7a-2*

3J7a-3

3J7a-4*

499
501
503
505
507

Chair: Yoshiki Yamakoshi (Gunma Univ.)

A high-performance spatio-temporal displacement smoothing filter for myocardial strain imaging
Shuhui Bu†, Tsuyoshi Shiina１, Makoto Yamakawa１, Hotaka Takizawa (Univ. Tsukuba; １Kyoto Univ.)
Examination of parameters depending on scatterer density for quantification of liver fibrosis
Hiroshi Eduka†, Tadashi Yamaguchi, Naohisa Kamiyama１, Hiroyuki Hachiya２(Chiba Univ.; １Toshiba Medical Systems; ２Tokyo Inst. Tech.)
Measurement of scatterer-size dependent frequency characteristics of high frequency ultrasonic echoes forassessment of red blood cell aggregation
Nobutaka Saitoh†, Hideyuki Hasegawa, Hiroshi Kanai (Tohoku Univ.)
An analysis of the pulse wave for the blood vessel evaluation
Masashi Saito†, Mami Matsukawa, Yoshiaki Watanabe (Doshisha Univ.)

509
511

513
515

16:00-16:05 Break
16:05-17:05 Medical ultrasound
3J7b-1
3J7b-2*
3J7b-3

3J7b-4Chair: Akira Yamada (Tokyo Univ. A&T)

Micro bubble adhesion to target wall by ultrasonic wave frequency sweep method
Yoshiki Yamakoshi†, Takashi Miwa (Gunma Univ.)
Ultrasound based multi-functional imaging using size dependent characteristics of phase change nano droplet
Rei Asami†, Takashi Azuma, Ken-ichi Kawabata (Hitachi)
Calorimetric method for measuring high ultrasonic powers using distilled water as the heating material: Eliminating
the effects of acoustic streaming, viscous heating and thermocouple position
Tsuneo Kikuchi†, Takeyoshi Uchida (AIST)
Viscoelasticity estimation of soft tissue for estimation of heat generation in application of ultrasonic surgicalknife
Naoki Suzuki†, Hideyuki Hasegawa, Hiroshi Kanai (Tohoku Univ.)
17:05-17:15 Closing Ceremony

517
519

521

523

USE2008
The 29th Symposiumon
ULTRASONICELECTRONICS

Tuesday, November 11, 2008

1J1-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 1- 2
11-13 November, 2008

Study on Fast Recovery of Elastic Constants of Metallic
Thin Films by Resonant-Ultrasound Spectroscopy.
超音波共鳴法を用いた金属薄膜の弾性定数の高速回復現象に関する研究
Takeo Nakashima1‡, Nobutomo Nakamura1, Hirotsugu Ogi1, Masahiko Hirao1,
Masayoshi Nishiyama2 (1 Grad. Sch. Eng. Sci., Osaka Univ.; 2 Reno. Cent. Instru.,
Osaka Univ.)
中島丈雄 1‡，中村暢伴 1，荻博次 1 , 平尾雅彦 1 , 西山雅祥 2 （1 大阪大 基礎工; 2 大阪大 機器セ）

1. Introduction
It has been reported that the recovery andrecrystallization occur in thin films after thedeposition, and they continue for several hours or
several days. During this period, the microstructure
and residual stress evolve. X-ray diffraction,1)
positron annihilation,2) atomic-force microscopy,3)and curvature measurement4) have been used forstudying the mechanism of them. However,recovery behavior of elastic constants has not beenstudied because of difficulty of the measurement,
despite that the elastic constants are required fordesigning the devices.
In this study, we propose a new method forstudying the recovery of the elastic constants,
which is based on the resonant-ultrasoundspectroscopy.5) This method enables the continuous
monitoring of the change in the elastic constants
during and after the deposition. Considering thatthe elastic constants change with the microstructure,
we can evaluate the microstructure by measuring
the elastic constants, and it gives us the valuableknowledge to clarify the recovery mechanism ofthin films. We show the measurement setup
integrated in a sputtering system, and the recoveryof the elastic constants of Ag thin films on Si
substrate.
2. Specimens and Experiment
Metallic thin films such as Cu, Ag, Au and Al
were deposited on (001) plane of a single-crystal Si
substrate (3.000 mm × 3.500 mm × 0.100 mm) by
the RF (or DC) magnetron sputtering method atroom temperature. Background pressure was 1.7
× 10-4 ~ 6.3 × 10-3 Pa, and the deposition was
performed in Ar gas at a pressure of 0.4 Pa.
Deposition time was 15 ~120 min at the sputtering
rate of 0.4 ~ 0.8 Å/s. Film thickness, which wasmeasured by the x-ray reflectivity measurements8)
after the measurement, was 82 ~ 400 nm.
Resonance frequencies of the free vibration of alayered specimen consisting of a substrate and athin film depend on their elastic constants.6) By

DC or RF power source

Metallic target
Specimen
Thermocouple

Piezoelectrictransducers

Vacuum pump

Output signal

cw signal(±5 V)

Temperature

Controller

Amplifier(60 dB)

Synthesizer
Control

Fig. 1 Setup of sputtering/RUS monitoring system.

monitoring the resonance frequency, we canevaluate the change of the thin-film elastic
constants before, during and after deposition.
Figure 1 shows our measurement setup. Resonancefrequency is measured by a tripod needle-shapesensor, which is placed in the deposition chamber.
The sensor consists of two piezoelectrictransducers and a thermocouple, and a substrate isput on them. The synthesizer inputs cw signal into
one of the transducers to oscillate the film/substrate,
and the other detects the oscillation amplitude. We
sweep the excitation frequency. When the cw
frequency equals the resonance frequency of thespecimen, a standing wave is generated, and aresonance peak appears in the resonance spectrum.
The resonance frequency is measured by fitting a

20∆C11/C11 (%)

Gaussian function to the peak. The thermocouple
measures the temperature at the back of substrate.
The resonance frequencies and the temperature aremeasured every 10 seconds. The vibration mode ofmonitored resonance frequency was identified bymeasuring the distribution of the out-of plane
displacement by the laser-Doppler interferometry.7)

10

0
0

3. Results and discussions
Figure 2 shows the typical changes oftemperature and the resonance frequency (∆f/f0) of
the Ag/Si specimen before, during and after
deposition. During the deposition, the temperature
increased linearly (Fig.2 (a)) and the frequency
decreased (Fig.2 (b)). After finishing the deposition,
the temperature decreased gradually, and thefrequency increased rapidly by 0.06 %. Thisfrequency increment originates from the following
factors: (i) temperature dependence of elastic
constants of the substrate and the thin film and (ii)the change of thin-film elastic constants. We cancalculate the temperature dependence of theresonance frequency of Si substrate from thetemperature dependence of the bulk Si elastic
constants, and it is shown in Fig. 2(c) by open
triangles (△ ). That of the thin film is assumed
negligible because the volume fraction of the thinfilm is very small (less than 0.3 %). We observedthat the temperature dependence of the elastic
constants hardly affect the resonance frequency,
and the recovery of the thin-film elastic constants
governs the change of the resonance frequency. We
then estimate the fractional change of the elastic
constant reflecting the recovery. Figure 3 shows

200

400
Time (sec)

600

800

Fig. 3 Elastic constant change, ∆C11/C11, calculated
from measured frequency change, ∆f/f0 of Ag thinfilm.

the fractional change of the in-plane longitudinalelastic constant (∆C11/C11) of Ag thin-film after
deposition, which was calculated from thecontribution ratio of C11 to the resonance frequency,∂C11/∂f, and the measured frequency change, ∆f/f0.5)
From this result, we found that the elastic constantincreased about 20 % in 5 minutes after finishingthe deposition.
The increment behavior of C11 in Fig. 3 is similar
to the change of the residual stress in Ag thin film
reported by Chason et al.4) As a cause of theevolution of the residual stress, they proposed amodel that is based on the flow of the excess atoms
into the grain boundaries of the polycrystalline film
due to a nonequilibrium surface chemical potential
during deposition. In the present study, we consider
that the flow of the atoms improve the binding
condition at the grain boundaries, which results in
the recovery of the elastic constants.

Frequency change,∆f/f0 (%) Temp ( ℃)

References
deposition
25
24
23
0.4

(a)
(b)
0.06

0.3

0.04

(c)

0.02

0.2

0
0

0.1

10
20
Time (min)

30

0
0

50

100

150

Time (min)Fig. 2
Changes of (a) temperature and (b)resonance frequency of the Ag/Si specimen before,
during, and after the deposition. Ag film is 255 nm
thick. (c) An inset enlarges the measured resonancefrequency (○) and temperature dependence of theresonance frequency calculated from that of theelastic constants of the Si substrate (△).

1. J. W. Pattern, E. D. McClanahan and J. W.
Johnston: J. Appl. Phys. 42 (1971) 4371.
2. A. Uedono, T. Suzuki, T. Nakamura, T. Ohdaira
and R. Suzuki: J. Appl. Phys. 98 (2005) 043504.
3. D. N. Buckley and S. Ahmed: Electrochem.
Solid-State Lett. 6, 3 (2003) C33.
4. E. Chason, B. W. Sheldon and L. B. Freund:Phys. Rev. Lett. 88 (2002) 156103.
5. N. Nakamura, H. Ogi, T. Nakashima, M. Hirao
and M. Nishiyama: Jpn. J. Appl. Phys. 46 (2007)
4450.
6. N. Nakamura, H. Ogi, N. Nitta, H. Tanei, M.
Fujii, T. Yasui and M. Hirao: Jpn. J. Appl. Phys.
45 (2006) 4580.
7. H. Ogi, K. Sato, T. Asada, and M. Hirao: J.
Acoust. Soc. Am. 112 (2002) 2553.
8. L. G. Parratt: Phys. Rev. 95 (1954) 359.

1J1-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 3- 4
11-13 November, 2008

光音響分光法による CdSe 量子ドットを吸着したナノ結晶 Si の熱拡散率評価
Characterization of thermal properties of porous Si film adsorbed with
CdSe quantum dots using photoacoustic technique
小鹿倉淳†、加藤侑志、沈青、豊田太郎（電通大 量子・物質工）
Jun Kogakura, Yushi Kato, Qing Shen and Taro Toyoda (Depertment of Appl. Phys. and Chem., The Univ.
of Electro-Com.)

A strong interest has been attracted on nanocrystalline Si (NSi) since it was found to show efficient luminescence at room
temperature. In addition, NSi has the thermal conductivity much smaller than that of Si. Therefore, the NSi has been expected tobe applied to light emitting devices, thermal insulators, and optical devices. But there are few reports about the thermal property ofNSi. In particular, the mechanism of thermal conductive process in the NSi adsorbed with molecules and/or quantum dots is notclear. In this paper, we report our experimental results on the measurements of thermal properties of NSi film adsorbed with CdSequantum dots using photoacousic technique.

1.

はじめに

結晶化されている Si とその表面に吸着された分子やナノ粒

ナノ結晶 Si (NSi)は可視発光特性が発見されて以来[1]、子間での熱伝導過程についてのメカニズムは、まだ十分には発光デバイスへの応用が研究されてきた。また NSi の持つ興解明されていない。そこで今回、NSi 表面に CdSe 量子ドット

味深い特性の一つとして、熱伝導率が Si と比べ極めて小さを吸着させた系での熱拡散率について評価を行った。CdSe

いことが挙げられる。そのため、マイクロシステムなどに適

量子ドットの物性はよく知られており、今回の試料作製法で用可能な新しい熱絶縁材料としても注目されている。ここでは吸着時間に応じて粒径と吸着量を変化できることから、ナ

光音響(PA)分光法は、光励起後の無輻射遷移緩和による熱エノ粒子のモデル材料として選んだ。透過型 PA 法を用いて PA

ネルギーを測定するため、半導体の光物性・熱物性・電子物

信号の変調周波数依存性を測定し、その結果から試料を均一性を非破壊的に評価することに対して有効である[2,3]。PA

と仮定した実効的な熱拡散率を計算し評価を行った。

法は、光熱変換現象に基づいた手法の一つである。PA 法を利用する測定手段には様々な利点がある。その特徴として次の

2.

実験法

ようなことが挙げられる。

2.1

試料作製法

(1)不透明、散乱が大きい試料に対しても光吸収評価が可能。

p型Si単結晶基板（ホウ素ドープ、厚さ 525 μm、面方位(2)非破壊、非接触の分析が可能。

〈100〉、抵抗率 1～10 Ω・cm）を基板として陽極化成法に(3)熱定数、光学定数や、緩和現象の同時評価が可能。

よりNSi試料を作製した。陽極化成法とは陽極にSi、陰極に(4)光源の変調周波数を変化させることで、試料の深さ方向

Ptを用いた電気溶解反応である。電流密度は 10 mA/cm2、陽の分析が可能。

極化成時間は 30 分の条件下で反応させた。

これまで我々は PA 法を利用して NSi/Si の２層構造試料におまた、化学吸着法によりCdSe量子ドットを吸着した[5]。

ける熱拡散率・熱伝導率を測定してきた[4]。一方、ナノ

CdSO4水溶液、N(CH2COOHNa)3水溶液、Na2SeSO4水溶液を混合し-----------------------------------------------------て作られる吸着溶液にNSiを浸漬させ、恒温槽で 10℃に温度

E-mail: kogakura@jupiter.pc.uec.ac.jpを保った状態で吸着を行った。今回、吸着時間は 2 時間とTable 1 Value of fmin and effective thermal diffusivity of NSi
adsorbed with CdSe QDs.
CdSe adsorbtion time [h]

0

2

24

fmin [Hz]

80

34

25

Effective Thermal diffusivity

28

12

8.6

PA Intensity [V]Figure 1 Arrangement of the transmission PA method.

no adsorbtion
CdSe 2h adsorption
CdSe 24h adsorption

0.01[×10-3 cm2/s]の変調周波数依存性を示す。PA信号はある周波数fmin において極小値を示し、この値を境に低周波数側を熱拡散が支配的な過程、高周波数側は光励起キャリア拡散によって生じる
発熱が支配的な過程と考えることができる[6, 7]。fminの値
から試料を均一と仮定した実効的な熱拡散率を下記に示す

1E-3
10

100

解析式(1)を用いて導出した[6]。

Modulation Frequency [Hz]α πf min ≈ L 5

Figure 2 Modulation frequency dependence of PA signal
intensity of NSi adsorbed with CdSe QDs.

(1)

ここで、α、Lはそれぞれ熱拡散率と試料の厚さを表す。fminの値と、その値を用いて算出した熱拡散率の値を表 1 に示す。

24 時間に限定した。

これらの結果から、CdSe量子ドットの吸着時間の増加に応じてfminの値が低周波数側にシフトすることが確認された。す2.2

PA 法の測定系

光源に 300W の Xe ランプからの白色光を分光器で単色化し、

なわち、CdSe量子ドットを吸着したNSiの熱拡散率がCdSeの吸着時間の増加に従い減少することを示している。この原因

チョッパーを通して変調して試料に照射した。試料表面ではとしては、CdSe-NSiもしくはCdSe-CdSe粒子間の界面抵抗に光照射により熱が発生し、表面層の空気が膨張と収縮を繰り

より熱拡散が妨げられることが考えられる。

返し、この空気の圧力変化を音響信号としてマイクロフォン

今後は過渡応答評価からキャリアの寿命や緩和過程を調で検出する。検出された音響信号はロックインアンプでチョべ、さらに詳細な熱物性とキャリアの移動特性の評価を行っッパーの周波数と同期させ検出した。

ていく。

今回の測定は光照射面と信号検出面が異なる側の面で行われる透過型 PA 法を用いた[6](Fig. 1)。励起光変調周波数

引用文献を変化させることによって試料の熱的性質を見積もること

1) L.T.Canham: Appl. Phys. Lett. 57 (1990) 1046.

ができる。光照射によって発生じた熱またはキャリアが試料

2) A. Rosencwaing, A. Gersho: J. Appl. Phys. 47 (1976) 64.

内を拡散し、光照射面とは反対側の面で音響波を発生し、こ3) 沢田嗣郎; 「光音響分光法とその応用―PAS」 (学会出版

れを検出する。今回は励起光の波長を 400 nm、変調周波数をセンター, 1982).

15 ~ 350 Hz と設定して PA 信号の変調周波数依存性の測定を

4) 加藤侑志: 学士論文: 電気通信大学量子物質工学科(2007).

行った。

5) S. Gorer, G. Hose: J. Phys. Chem. 98 (1994) 5338.
6) Q. Shen, T. Toyoda: Jpn. J. Appl. Phys. 39 (2000) 3164

3.

結果と考察

Fig. 2 に、CdSe 量子ドットを吸着した NSi 試料の PA 信号

7) M. D. Dramicanin, Z. D. Ristovski, P. M. Nikolic, D. G.
Vasiljevic D. M. Todorovic: Phys. Rev. B 51 (1995) 14226

1J1-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 5- 6
11-13 November, 2008

水熱合成法による KNbO3 エピタキシャル膜の作製と特性評価
Epitaxial KNbO3 Films Grown on SrRuO3/SrTiO3 using Hydrothermal Method
and Their Electromechanical Properties
石河睦生 1‡，宇津木覚 1，藤澤隆志 1，安井伸太郎 1，山田智明 1，黒澤実 1，森田
剛 2，舟窪浩 1 (1 東工大 総理工; 2 東大 新領域）

Mutsuo Ishikawa1†, Satoru Utsugi1, Takashi Fujisawa1, Shintaro Yasui1, Tomoaki Yamada1, Minoru
Kuribayashi Kurosawa1, Takeshi Morita2, Hiroshi Funakubo1, (1Institute of Technology; 2Frontire science,
The Univ. of Tokyo)

High quality epitaxial KNbO3 films were successfully grown on (100)SrRuO3//(100)SrTiO3 substrates by hydrothermal method.
The KNbO3 or KNbO3-based materials are one of the promising lead-free piezoelectric materials as an environmental friendly
material; however, the main interest in the KNbO3-based piezoelectric materials have limited on bulk ceramics materials owing to thedifficulty in thin or thick films preparation. Therefore the hydrothermal method has utilized for the growth of KNbO3 films. Because,hydrothermal method has number of advantages for fabrication method of ultrasonic transducers; low deposition temperature, good
conformability, high-purity deposition on a substrate. In this study, epitaxial SrRuO3 film was used as bottom electrodes, which weregrown on (100) SrTiO3 substrate by sputter method. KNbO3 films were prepared on (100) SrRrO3//SrTiO3 substrates at 210 °C byhydrothermal method. The KNbO3 films were 7.5 μm thicknesses, and the K/Nb ratio measured by EDS was 50/50. The piezoelectricperformance and material constants of the prepared KNbO3 thick film were measured.

3. 実験結果

KNbO3 は有力な非鉛系圧電材料の一つであり、また、大きな電気機械結合係数を有する1)ことから、超音波トランスデューサ材料として魅力的である。近年、開発が進む数十MHz以上の周波数の超音波送受信を行うデバイスを想定した場合、構造上は厚膜や薄膜のKNbO3結晶の利用が望ましい。しかし、KNbO3結晶は基板上への成膜が困難で、報告例が少なく、基板上へ成膜されたKNbO3結晶膜2)の圧電特性は不明
な点が多かった。最近、NaNbO3及び(K,Na)NbO3結晶膜の優れた圧電特性の報告3)があり、純粋なKNbO3 結晶膜における圧電特性の評価は重要となっている。そこで本研究では水熱合成法
4,5)を用いることで高品質な単結晶KNbO3 の成膜を行った。

Figure 1 に(100)SrRuO3 //(100)SrTiO3 基板上に水熱合成した KNbO3 膜の X 線回析(XRD, Philips
X'Pert MRD system）パターンを示す。

2. 実験方法
本研究では、KNbO3 単結晶膜を成膜する基板として、(100)SrRuO3 を成膜した(100)SrTiO3 基板を用いた。SrRuO3 は導電性酸化物であり、下部電極として用いることが可能である。はじめに厚み 0.5 mm の(100)SrTiO3 基板上に、スパッタ法により厚み 60 nm の(100)SrRuO3 膜を成膜した。次に、得られた(100)SrRuO3 //(100)SrTiO3
基板を保持具に固定し、出発原料と共にオート
クレーブ内に投入し密閉した後、温度 210 度で30 時間の水熱合成を行った。出発原料には 1.56
g の Nb2O5 を 9 mol/l の KOH 水溶液中に混合したものを用いた。
-----------------------------------------------------------Ishikawa.m.ai@m.titech.ac.jp

3200 KNbO
3

SrRuO 100

Intensity (arb. unit)

3011 KNbO 3
100 KNbO

3022 KNbO 3
SrRuO 200
3
SrTiO 200

1. はじめに

20

25

30

35

40

45

50

2θ (degree)

Fig.1 XRD pattern of KNbO3 film grown on(100)SrRuO3//SrTiO3 substrate using hydrothermal
method.
XRD パターンからは、(100)SrRuO3 //(100)SrTiO3 および KNbO3 の(100)と(011)が観察された。また、(101)面による X 線極点図形から、得られた KNbO3 膜の面内配向を確認し、基板に対してエピタキシャル成長していることが分かった。次に走査型電子顕微鏡(FE-SEM, HITACH
S-4800)を用い、KNbO3 膜の断面観察を行った結果を Fig.2 に示す。FE-SEM 像から、得られた(100)/( 011)配向エピタキシャル KNbO3 膜の膜

厚は約 7.5μm (成膜速度、7.5μm /30h)であった。
膜の組成は、EDX ( HORIBA, 7593H )を用いて分析した結果、K/Nb 比は 50/50 であった。

Vibration displacement (nm)7.5 μm KNbO3

60 nm SrRuO3
SrTiO3
Fig.2 Cross-sectional SEM photograph of 7.5
μm-thick epitaxial KNbO3 film.
次に、(100)/(011) KNbO3 膜の表面をメタルマ
スクで覆い、電子ビーム蒸着装置（ANELVA）
を用いて直径 100μm の Pt 上部電極を作製した。
この Pt 上部電極と SrRuO3 下部電極を用い、KNbO3 膜の分極－電界（P-E）特性を、周波数100 kHz において測定した。得られた結果から、Fig. 3 のようにヒステリシスループおよび約-40
kV/cm のインプリントが観察された。また、電圧 150 V(電界 200 kV/cm)加えた残留分極値は約28 μC/cm2 であった。
- 3 0 V (-4 0 k V /c m )2

Polarization (μ/cm )

30
20
10
0
-10
-20
-30
- 2 0 0- 1 5 0- 1 0 0 - 5 0

作製したユニモルフ振動子の先端の振動変位を Laser Doppler Velocimeter（LDV, Polytec OFV3001）を用いて測定した結果を Fig.4 に示す。
駆動周波数については、ユニモルフ振動子の共振周波数の影響を受けていない 50Hz とした。

0

50 100 150 200

V o lta g e (V )Fig.3 P - E hysteresis loops for (100)/(011)-oriented
epitaxial KNbO3 films grown on(100)SrRuO3//(100)SrTiO3.
次に、Dicing saw(Disco DAD321) を用いて(100)/(011)KNbO3//(100)SrRuO3//(100)SrTiO3 基
板を幅 1.5mm×7mm で切断し、片端を固定する
ことで長さ 3.53mm のユニモルフ振動子を作製した。振動子の表面には真空蒸着装置（ULVAC）
により幅 1mm の Au 上部電極を形成している。

40
35
30
25
20
15
10
5
0

0 0.5 1 1.5 2 2.5 3 3.5 4
Driving voltage (V)Fig.4 Relationship between vibration displacement
and applied voltage at 50 Hz.
以上の結果から、振動変位は駆動電圧に対して線形的に増加することが分かった。
4. 考察
水熱合成法を用いて膜厚 7.5μm の(100)/(011)
配向したエピタキシャル KNbO3 膜を成膜した。
組成は K/Nb = 50/50 であり、高品質な KNbO3の厚膜が得られることが分かった。水熱合成法
によりエピタキシャル KNbO3 膜を用いて試作したユニモルフ振動子の圧電効果を利用し、振動変位を測定することが可能であり、今後は、
圧電定数等の材料定数を測定し報告を行う予定である。また、(111) SrRuO3//(111)SrTiO3 基板等を用いることで結晶方位依存について、比較検討を行いたいと考えている。
謝辞
本研究の一部は井上科学振興財団の研究助成を受けて行われました。
引用文献
1. K. Nakamura, et al, J. Appl. Phys., 91, 11,
pp.9272-9276 (2002)
2. T. Arai et al, JJAP., 42, pp.6019-6022 (2003)
3. I. Kanno, et al., IEEE Transaction on UFFC.,
54(12), pp.2562 – 2566 (2007)
4. T. Morita, et al., J. Mater. Res., 19(6), pp.
1862-1868 (2004)
5. Wojciech L. Suchanek, Chem. Mater.
vol.16, pp.1083-1090 (2004)

1J3-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 7- 8
11-13 November, 2008

FBG を用いたファブリ・ペロー干渉計による振動センシングの検討
Vibration sensing by using Fabry-Perot interferometer with FBG reflectors
和田篤†，杣友宏行，田中哲，高橋信明 (防衛大)Atsushi Wada, Hiroyuki Somatomo, Satoshi Tanaka, and Nobuaki Takahashi (National Defense Academy)

In vibration sensing by use of a FBG based on intensity modulation, light incident on a FBG is narrow-band light tuned
to the slope in a transmittance spectrum of the FBG. Since the sensor sensitivity is proportional to the slope of thespectrum curve, enhancement of the sensitivity requires steeper slope of the curve. In this paper, vibration sensing by
use of Fabry-Perot interferometer with FBG reflectors (FBG-FPI) is numerically investigated. Because a transmittancespectrum of an FBG-FPI has steeper slope, the FBG-FPI can yield improvement in sensitivity of the sensing.

1. はじめに
1.0

2. 数値計算
数値計算によって FBG と FBG-FPI の反射率
スペクトルを算出し，両者を比較する．数値計算には特性マトリックスの手法を用いた[1]．算出した
FBG の反射率スペクトルを Fig. 1 に示す．数値
計算のパラメータは紫外光に感度を持つファイバに周期 1060 nm の位相マスクを用いて紫外光を照射して屈折率分布を構成する作製手法を想定して選択した．FBG の周期 Λ を 530 nm，長さ
LFBG を 4 mm，ファイバの屈折率 n を 1.458，紫外
光感光によるファイバ屈折率の増加率 Δn/n を0.01% とした．
FBG 2 つを反射鏡として用いて共振器を構成しているファブリ・ペロー干渉計 (FBG-FPI)の反射率スペクトルを Fig. 2 に示す．FBG-FPIのモデルを Fig. 3 に示す．このモデルでは同じ条
件の共振器の鏡として用いる FBG 間の距離 LFPI
は 4 mm とした．また，両端の FBG についてはFig. 1 に示した計算と同様に，周期 Λ を 530 nm，
長 さ LFBG を 4 mm ， フ ァ イ バ の 屈 折 率 n を1.458，紫外光感光によるファイバ屈折率の増加率
Δn/n を 0.01 % とした．Fig. 2 を見ると FBG-FPIの反射率スペクトルが Fig. 1 に示した単一の FBG----------------- ------------------------------------------†

a24wada@nda.ac.jp

Transemittance

0.9
0.8
0.7
0.6
0.5

1545.21545.41545.61545.81546.0

Wavelength (nm)Fig.1 Transmittance spectrum of FBG.

1.0

Transmittance

これまで我々は，固体振動や水中音響の計測を行うため，強度変調方式に基づいた各種の FBG
センサの提示を行ってきた．この方式では，FBGの透過（あるいは反射）スペクトルの傾斜部に同調した狭帯域光を FBG に入射させると，FBG に振動や音圧を印加したときに透過光（反射光）が強度変調を受けることを利用し，簡単な構成でひずみや圧力の波形を直接観測することができる．また，この方式によるセンサの感度は FBG の透過（反射）スペクトルの傾斜部分の傾きに依存し，高感度な計測を行うためには，この傾斜が急峻であることが必要となる．本研究では FBG を用いて構成したファブリ・ペロー干渉計 (FBG-FPI) による振動計測の検討を数値計算によって行った．FBG を用いた
ファブリ・ペロー干渉計の透過スペクトルは単一のFBG によるものよりも急峻な傾きを持つ為，計測の高感度化が期待できる．

0.8
0.6
0.4
0.2
1545.21545.41545.61545.81546.0

Wavelength (nm)Fig. 2 Transmittance spectrum of FPI with FBG
mirrors.

Fig.3 FPI with FBG mirrors.

の反射率スペクトルよりも急峻な傾斜部を持っていることを確認できる．

よりも急峻な傾きの傾斜部を持ち，計測の高感度化が期待できることが確認できた．

傾斜の急峻さを比較するため，単一の FBG と
FBG-FPI のそれぞれについて反射率スペクトルの傾きを算出した．算出した傾きを Fig. 4 に示す．
Fig. 4 を見ると，FBG-FPI の反射率スペクトルの傾きは単一の FBG の反射率スペクトルの傾きの約10 倍であることがわかる．

参考文献
1. 田中 哲，横須賀 泰輝，高橋 信明，第52回春季応物講演会予稿集，31p-D-7，p.1354，
2005．

40

dT/dλ

20
0

Transmittance

1.0
FBG
FBG-FPI

0.8
0.6

Strain (με)
0
4
8
12

0.4

-20

0.2
-40

1545.21545.21545.41545.61545.81545.41545.61545.81546.0

Wavelength (nm)1546.0

Wavelength (nm)FBG-FPI にひずみを加えた場合の反射率スペ
クトルを算出した．ひずみは 2 つの FBG を含む共振器全体に加えるものとした．結果を Fig. 5 に示す．算出した反射率スペクトルを基にひずみに対するスペクトル関数の波長シフト量を計算したと
ころ， 1.6 pm/μεであった．一方，単一の FBG に対してもひずみを加えた場合の反射率スペクトルを計算し，波長シフト量を計算したところ，FBG-FPIと同様に 1.6 pm/με であり，今回示した条件下では両者の間に有意な差は見られなかった．
FBG-FPI の波長シフト量は FBG 間の距離に依存しており，LFPI が大きい場合には単一の FBGよりも大きな波長シフト量が得られた．
強度変調方式の計測を想定し，単一の FBG と
FBG-FPI のそれぞれについて，反射率スペクトルの勾配が大きな点を動作点に選び，ひずみに対する透過率の変化を調べた．算出した透過率のひ
ずみ依存性を Fig. 6 に示す．10 με 程度のひずみに対して単一の FBG の透過率が 5% 程度しか変動していないのに対し，ファブリ・ペロー干渉計の透過率は 60% 程度変動しており，強度変調
方式の計測の高感度化が期待できることが確認で
きる．
3.

まとめ

FBG を用いて構成したファブリ・ペロー干渉計
による高感度振動センサの検討を数値計算によって行った．数値計算には特性マトリックスの手法を用いた．FBG-FPI の透過スペクトルが単一の FBG

1.0

FBG
FBG-FPI

0.9

TransmittanceFig. 4 Slope of transmittance spectra of FBG and
FBG-FPI.

Fig. 5 Strain dependence of transmittance spectrumof FBG-FPI.

0.8
0.7
0.6
0.5
0.4
0.3

0

2

4

6

8

10

12

Strain (με)
Fig. 6 Strain dependence of transmittance of FBG
and FBG-FPI.

1J3-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 9- 10
11-13 November, 2008

ラム波を用いた高効率な光モード変換器
High efficient optical mode converter using Lamb wave
齋藤光希†,

中川恭彦,

垣尾省司（山梨大院・医工）Koki Saito† , Yasuhiko Nakagawa and Shoji Kakio(Interdisciplinary Graduate School of Med. Eng., Univ. of
Yamanashi)
When Lamb wave propagates in a crystal, the photo-elastic effect induces a refractive index change in a crystal and makes phasegrating in a crystal. Therefore optical mode conversion occurs in the crystals which Lamb wave propagating. Using this phenomenon,
it can be expect the Lamb wave type crystal substrate apply to the optical communication system. In this study, we had theoreticallyexamined the optical mode conversion during refractive index period structure. The theoretical calculation result predicted a least
power for the mode conversion at a mode1 in various modes. Furthermore, when Lamb wave Λ =270μm and substrate thickness
H=20μm in mode 1, Lamb wave power P100 to need for 100% optical mode conversion was 12.8mW. Which is very small power forthe optical mode converter.

1. はじめに本報では、ラム波型結晶基板の光通信への応用を目指し、ラム波[1,2]による屈折率周期構造
中の光波伝搬について理論的な検討を行った。
ラム波型結晶基板に光を入射すると、結晶中のラム波と光波との相互作用により、モード変換が生じる。これらについて検討を行った結果、高効率でモード変換が行えることを確認した。

とすると、媒質中のトータル場は次式となる。

2. ラム波による屈折率周期構造
ラム波解析に用いる座標系を図１に示す。ラ
ム波の伝搬方向を X１方向、基板表面に垂直な方向を X3 方向、ラム波波長がΛ、基板の厚さ Hとして波動解析を行った。ラム波は,圧電基本式を満たし、(1)、(2)式の運動方程式とラプラスの方程式を満す。
 uj
2



t

E
 c ijkl

2

 uk
 
  ikS 0
xixlxix k2e ikl

 2u k 2
 e kijxi x lxi x k

…(1)

2

…(2)

基板表面と裏面による粒子変位、応力、電気的変位、電位の連続性による８つの境界条
件下で一般解(3),(4)式が求まる。
u j   j exp( ikbx 3 ) exp( ikx 1  i  t )…(3)   4 exp( ikbx 3 ) exp( ikx 1  i  t )…(4)

ラム波による結晶中の屈折率は, (4),(5)式により求まる。
1
 B ij  p i j k l S k l   i j k E k  c .c . 2 B I  p IJ S J   Ik E k  p IJ S J   Ik  , k
3.

…(5)
…(6)

光モード変換は図 1 の LiTaO3 基板を用いた。
X2 方向偏波光と X3 方向偏波光の X1 軸に沿った
振幅,波数ベクトルを…(7)---------------------------------------------------------------------------

nakagawa@es.yamanashi.ac.jp

E T   2 ( x1 )E 2  3 ( x1 )E 3

H T   2 ( x1 )H 2  3 ( x1 )H 3…(8)

ここで,ラム波による屈折率周期場の波数を K とすると、波数整合条件は次式となる。

2  K  3…(9)K  3  2 

2 n 330

2 n 330

2  ( n 33  n 22 )0

   0 /( n 33  n 22 )…(10),(11)
この関係を用い、振幅に関する関係式は、
以下のように求まる。[3]1d 2 ( x1 ) 2 (  j 2 )E 20   2  0 0   23  E 30 3 ( x1 )
2
dx1
d
1
3 ( x1 ) 2 (  j 3 ) E 30   2  0 0   32  E 20  2 ( x1 )
2
dx1
…(12)

(12)式を解くと、X２方向偏波光と X３方向偏波光の振幅はそれぞれ

2(x1 ) cos(x1 ), 3(x1 )  j C32 /C23 sin(x1 )…(13)

ここで、C23 と C32 は結合係数であり、*C 23  C 32
[j

0
1
*
( E 20  23  E 30 ) dx 3 ]480  0  H

  C 23C32

ラム波による光モード変換理論(  2 ( x 1 ),  2 ), (  3 ( x 1 ),  3 )Fig.1 polarized wave rotation experimental Lamb wave
substrate.

…(14)

100％モード変換するに要するラム波パワー
を P100 とすると、P100   ( D / L2 ),   2 /(2 ) 2…(15)

ここで、D：IDT の交差幅、Ｌ：相互作用長である。

LT H =130 m

4. 計算結果

1 .0

図 2 に H=130μm,Λ=132μm の LT.X-Y 伝搬ラ

0 .8
0 .6
0 .4
0 .2
0 .0
100

150

200

250

300

350

  m )Fig.5 Λ dependency with η.(H=130μm)
L T  = 1 3 2  m (         m )0 .1 00 .0 8

W ・m)

きのηの H 依存性を示す。
ここで、D=1mm,L=10mm とすると(15)式より
Λ=270μm,H=20μm,の時 P100=12.8mW と小さい
ラム波パワーで光モード変換できる。

W・m)2

ム波の各モードの K の計算値を示す。また図 3に各モードのηの計算値を示す。図 4 には図 3で最もηが小さかった Mode１(23.29MHz)での基板中の歪みの分布を示す。図から歪み S13 が基板中に大きく分布しているため、小さなラム波パワーで光モード変換が起こることがわかった。図 5 に H=130μm としたときのηのΛ依
存 性 を 示 す 。 図 6,7 に 、 Λ を そ れ ぞ れ
132μm( 0 =0.63μm),270μm( 0 =1.3μm)としたと

0 .0 60 .0 4

4

0 .0 02

K (%)

0 .0 2

0

2

20

40

60

80

100

120

140

160

H [ m ]Fig.6 H dependency with η.(Λ=132μm)
0

20

40

60

80

100

Frequency(MHz)Fig.2 Analytical result of K
lamb wave.

2in each mode for
0.04

・ m)
(W

LT H=130m , =132m
1e+8
1e+7
1e+6
1e+5

 (W・m)  270m (=1.3m )

0.05

1e+4

0.03
0.02
0.01

1e+3
1e+2

0.00

1e+1
1e+0

0

Mode 1

1e-2
20

40

60

80

100

Frequency (MH z)

Fig.3 Analytical result of Lamb wave power in eachmode for polarized wave rotation.
1e-6

F=23.29MHz,H=130m,=132m

Strain(S23,S13)

5e-7

S 23

0

-1e-6

S 13
-2e-6

0.2

60

80

100

120

Fig.7

H dependency with η.(Λ=270μm)

5. あとがき
本報告では、ラム波による光モード変換について検討を行い、論理計算の結果から、高効率な光モード変換器を提案した。
今後は、さらに高い変換効率を得るための設計指針を理論的、実験的に求める予定である。
参考文献[1] Y. Nakagawa et al. Jpn.J.Appl.Phys.,
42(5B), 3086-3090, 2003.
[2] Y. Nakagawa et al. Jpn.J.Appl.Phys.,
43(5B), 3020-3023, 2004.

-5e-7

-2e-6
0.0

40

H(m )

1e-1
0

20

0.4

0.6

0.8

Position (X3/H)

Fig.4 Strain distribution for mode1.

1.0[3] 小山次郎,西原浩共著，“光波電子工学”，
コロナ社

1J9-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 11- 12
11-13 November, 2008

タイムリバーサルによる陰影領域中の物体の探知
Detection of objects in shadow region using time reversal
鶴ヶ谷芳昭 1‡，菊池年晃 2，水谷孝一３ (1NEC; 2 防衛大;3 筑波大）

Yoshiaki Tsurugaya1†, Toshiaki Kikuchi2 and Koichi Mizutani3 (1NEC; 2NDA; 3Univ. of Tsukuba.)

A method of detecting targets present in the shadow area of an obstacle like a seamount by applying a time reversal is described.
Transmission signals of two types with a different phase are used. First, the signal of a normal phase is transmitted in the propagation
environment without a target, and the signal received with each element of a transducer array is preserved. Next, the signal of ananti-phase is transmitted in the propagation environment with the target, and the signals received with each element of the transducer
array are preserved. The received signals of two types are added in the vector. The time reversal sound field (TRSF) to the target isformed by time-reversing and re-emitting the added signal.

1. はしがき
最近、タイムリバーサルを利用した水中物体の探知に関する研究が注目されている 1,2)。 C.
Prada らは、複数ターゲットからの反射波にタ
イムリバーサルを適用した波を放射して、ター
ゲットに収束する波を生起させた。その波に対する反射波に再びタイムリバーサルを適用して再放射する。この操作を繰り返すことによって、個々のターゲットに収束する波を生起させた。この方法は、タイムリバーサルを反復する必要がある。一方、鶴ヶ谷ら 3)は、音源からの進行波を除去して、ターゲットからの前方散乱波に対してタイムリバーサルを適用して、個々のターゲットに収束させた。この方法では単純な参照音場を用いたが、ターゲットの配置によって、一部のターゲットの識別が困難になることがある。そこで、今回は複雑な伝搬環境における参照音場について検討する。
2. タイムリバーサル音場
浅海中に設置された音源と変換器アレイを用いて、次式に従って、タイムリバーサル音場を求める。
JPpc (r , z; t ) = å ò Gw (r , z , z j )Gw* ( R; z j , z ps )j =1

´eiwT S * (w )e - iwt d w(1)
ここで Gw ( R; z j , z ps ) は、音源からアレイ素子に及ぼすグリーン関数で、Gw (r , z , z j ) はアレイ素

Fig. 1 Schematic
simulation model.

representation

of

the

ような、海山を有する浅海域を設定する。平坦部の水深は 100m、海山頂部の深さは 50m である。音源から海山と変換器アレイまでの距離はそれぞれ 1km と 3km である。はじめは、海山を有する海域で、ターゲットを挿入せずに、タイムリバーサル音場を求める。すなわち、(1)式を用いて、音源からアレイの間の点(r,z)での音圧を求め、その音圧振幅分布を Fig. 2 に示す。
距離 3km に位置する変換器アレイから放射されたタイムリバーサル波は、距離 1km に位置す
る海山を越えて音源位置(距離 0m、深度 50m)に収束することが分かる。
次に、ターゲットを挿入した場合のタイムリ
バーサル音場を求める。ターゲットの大きさは縦横共に 2m で、その音速は 4350m/s である。
それを音源からみて海山の陰影部に相当する
位置(距離 1.5km 深度 70m)に挿入する。そのときのタイムリバーサル音場は Fig. 2 とほとんど子から点(r,z)に及ぼすグリーン関数である。
S (w ) は音源から放射されるパルスの周波数スペクトルである。放射されるパルスは中心周波数 500Hz のトーンバースト波である。グリーン関数の算出には結合モード法を用いる。
3.

シミュレーション

3.1 海山の陰影にある物体
複雑な伝搬環境の一つとして、Fig. 1 に示した-----------------------------------------------------------y-tsurugaya@bp.jp.nec.com

Fig. 2 TRSF in shallow water with a seamountby a normal method.

同じで、ターゲットの付近の音場には全く変化が見られない(図は省略する)。その理由は、音源から変換器アレイへ進行する進行波のレベ
ルがターゲットによる散乱波のレベルより大きいためと考えられる。
次に、進行波の成分を除去して、散乱波のみのタイムリバーサル音場を求める。進行波成分を除去するために、音源から放射する二種類の音波パルスを用いる。まず、始めに、ターゲッ
トが挿入されない状態(参照音場)で、音源から正相の音波パルスを放射して、変換器アレイの各素子で受波して、保存する(参照波)。次に、ターゲットを挿入した状態(ターゲット音場)で、逆相の音波パルスを放射して、変換器アレイの各素子で受波する(ターゲット波)。そして先に保存した参照波とターゲット波をベクトル的に加算する。この操作によって、進行波の成分は打ち消されて、変換器アレイの各素子にはターゲットからの散乱波の成分のみが残される。
この残された成分を、各素子から放射することにより、散乱波のみのタイムリバーサル音場が求められる。
求められた散乱波に対するタイムリバーサ
ル音場を Fig. 3 に示す。この図から明らかなよ
うに、ターゲットの位置にのみ収束し、音源位置への収束はみられない。また、Fig.2 と比較す
ると、収束点の上部のレベルがかなり低い。すなわち、進行波成分がほとんど現れていないことが分かる。更に、Fig. 2 と比較すると、Fig. 2で見られる海山は Fig. 3 では全く見ることが出来ない。このことから、散乱波のタイムリバー
サル波には、海山などの伝搬環境は影響しない
ことが分かる。

Fig. 3 TRSF for the target after traveling wave
is deleted.
3-2 物体の陰影にある物体
我々は先に 3)、参照波を作成する伝搬環境として単純な伝搬環境を用いた。しかし、前項に示したように、複雑な伝搬環境でも、参照波の作成が可能であることが明らかになった。そこで、ここでは一部のターゲットを伝搬環境に含めることを検討する。二つのターゲットがほぼ水平に配置した場合、Fig. 4 に示したように、

距離 1.7km、深度 50m にあるターゲット(第 2ターゲット)の識別が困難になりやすい。これは第 2 ターゲットには、音源からの進行波と距離
1.5km、50m 音源にある第 1 ターゲットの散乱波が当たるためと考えられる。そこで、第 1 ターゲットを伝搬環境の中に含めて、参照波を求める。そして第 2 ターゲットに対するタイムリ
バーサル音場を求めた結果を Fig. 5 に示す。第2 ターゲットのみに収束していることが分かる。
4. まとめターゲットのタイムリバーサル音場を求める
際の参照音場について検討した。その結果、海山のある伝搬環境や、不要なターゲットを含む伝搬環境をも参照音場として利用出来ることが明らかになった。

Fig. 4 TRSF for two targets that queue up
horizontally.

Fig. 5 TRSF for the target right in Fig.4.

引用文献
1. C. Prada, et al : J.Acoust.Soc.Am. 99(1996)
2067.
2. G. Montaldo et al : J. Acoust. Soc. Am. 115(2004) 776
3. Y. Tsurugaya et al: Acoustics’08 Paris. 2aSPb(2008) 1395

1J9-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 13- 14
11-13 November, 2008

Design for Aplanatic Fresnel Acoustic Lens
アプラナートフレネル音響レンズの設計
Yuji Sato1‡, Koichi Mizutani1 , Naoto Wakatsuki1 , and Toshiaki Nakamura2(1University of Tsukuba; 2National Defense Academy)
佐藤裕治 1‡，水谷孝一 1，若槻尚斗 1，中村敏明 2 (1 筑波大院 シス情工; 2 防衛大 地球海洋）

1. Introduction
Underwater acoustic lenses are useful device
for the beam forming of an underwater imaging
system because the lenses can make the system size
small. An Autonomous Underwater Vehicle“URASHIMA” equipped the acoustic lens for the
obstacle avoidance sonar for an actual example1).
A low-frequency sound must be used for longrange detection. The aperture of lens should beenough larger than the wavelength and the lensbecomes thick. It is a problem because the soundpressure is seriously attenuated in the lens and it
becomes heavy. A Fresnel lens which has stair-likesurface is useful to reduce the thickness and it canfocus higher sound pressure than an ordinary
convex lens2). Another problem is an aberration. A
spherical lens has a spherical aberration. The
spherical aberration is compensated in asphericallenses but a coma aberration appears in case of an
oblique incidence. An aplanatic lens has two
aspherical surfaces and the spherical and coma
aberrations are both compensated in paraxial area3).
Thus, it is considered that an aplanatic
Fresnel lens is better than the aplanatic lens. We
designed an aplanatic Fresnel lens using an opticalmethod and evaluated it using ray tracing method
and the 2 dimensional finite difference time domain(2D FDTD) method.
2. Design for aplanatic Fresnel lens
An aplanatic lens is designed by solving
following equations.
h(1)
sin u 2 = ,f(2)
a + nb + c = nd + s ,(3)
e = d + s − f cos u 2 − a ,2(4)b 2 = e 2 + ( f − c ) − 2e( f − c ) cos u 2 ,
f −c
b ,
(5)
=
sin u1 sin u 2
n sin u1da.
(6)=
dh n cos u1 − 1Here, n is the refractive index of the lens and other------------------------------------------------------------

yuji@aclab.esys.tsukuba.ac.jp

parameters are shown in Fig. 1. The 1st surface isdetermined by a and h, and the 2nd surface isdetermined by c and u2. There is an infinite shape oflens which has same d and f. The shapes are
determined by the central curvature radius of the 1st
surface r1. It is called as bending. A sphericalaberration and the thickness of the rim become
smallest when the r1 satisfies the following
relation4).
(2n + 1)n .
1(7)=
r1 2(n − 1)(n + 2 ) f
An aplanatic Fresnel lens is designed by
combining some lenses, which are designed to havethe same focal point. Additionally, if the 1st or 2nd
surfaces of these lenses are overlapped each otherthe shape becomes simple. Fig. 2 shows an instanceof the 2nd surfaces overlapping. The lens 1 which issmaller than lens 2 is assigned to the inner part ofthe combined lens and the lens 2 is assigned theouter part. d1 is determined arbitrarily. d2, d3, … ,dN
are derived by the following equation.
(N − 1)λw(8)dN =+ d1 .
n −1
Here, λw is the wavelength in water.
Designed lenses are shown in Fig. 3. The
lenses in Fig. 3 (b) and 3 (c) are named as “the First
surface Stepped aplanatic Fresnel lens (FSF)” and“the Second surface Stepped aplanatic Fresnel lens(SSF)”, respectively. Fig. 3 (a) shows the outer lensof the FSF which is named as “the Aplanatic
Convex lens (AC)”. FSF and SSF are thinner thanAC and each lens has 12 steps.
Ray

a e
u b
1

h

f
c

u2
Lens
s
d
Fig. 1 Diagram of an aplanatic lens.
Lens N
Axis

Lens 3
Lens 2
Lens 1d1
d2
d3

Fig. 2

Combined lensCombining lenses for a Fresnel lens.

100(a) AC(b) FSF (c) SSF

0

0

-100
-50

0 -50

0 0
50
x (mm)
Fig. 3 Shapes of lenses.
(a) Aplanatic Convex lens (AC),(b) First surface Stepped aplanatic Fresnel lens (FSF),(c) Second surface Stepped aplanatic Fresnel lens (SSF).
y

Relative pressure (dB)y (mm)

-10
-20

SSF
FSF
AC

-30
0
-10
-20
-30
0

0.2

0.4

0.6

Fig. 5 On ξ axis characteristics.
0

Acoustic Lens

-10

Focal Point
SourceFig. 4 Arrangement of the 2D FDTD analysis.

3. 2D FDTD analysis
Converged sound pressure fields of the 3lenses are evaluated by the 2D FDTD method. An
arrangement of the 2D FDTD analysis is shown in
Fig . 4. The origin is located on the center of the 1st
surface of FSF or SSF. The x axis is identical to thelens axis and the y axis lies on the radial direction.
The ξ axis is passing through the origin and the
focal point and η axis is parallel to the y axis andpassing through the focal point. The lens is assumed
to be made of silicone rubber which has 1000 m/s
sound speed, 1490 kg/m3 density and 1 dB/λattenuation. Here, λ is the wavelength in the lens.
The lens is surrounded by water which has 1500
m/s sound speed and 1000 kg/m3 density. A plane
wave is incident to the lens with the incidence angle
θi. The incident wave is 500 kHz and 25 cycles
burst wave. The discretizing interval is 0.2 mm inspace and 0.02 ms in time. The sound field issurrounded by the absorbing layer and the exterior
boundary is Mur’s 1st order non-reflective
boundary.
The characteristics on ξ and η axes with θi =0 and 10 (o) are shown in Fig. 5 and 6, respectively.
These are the integrated RMS of the sound pressure
normalized by the maximum sound pressure of the
FSF with θi = 0o. The sound pressures of FSF and
SSF are larger than AC. Thus, the 2 aplanatic

Relative pressure (dB)

x

SSF
FSF
AC

-20
-30
0
-10
-20
-30
-20

-10

0

10

20

Fig. 6 On η axis characteristics.

Fresnel lenses have better property than AC. The
sound pressure of SSF is slightly larger than that of
FSF. The focal sound pressure of the SSF is larger
than that of FSF about 0.5dB.
4. Conclusion
The 2 shapes of the aplanatic Fresnel lenses
were designed and evaluated using the 2D FDTD
method. In conclusion, the property of SSF is bestof all. It is future problems to design the mostappropriate lens shape because the SSF designed inthis report is one of the extreme shapes.
References
1). S. Tsukioka, T. Aoki, H. Ochi, T. Shimura, T. Sawa, T.
Nakamura, T. Anada, I. Kaihou and H. Noda: Jpn. J. Appl.
Phys. 41 (2002) 3970.
2). Y. Sato, K. Mizutani, N. Wakatsuki, and T. Nakamura: Jpn. J.
Appl. Phys. 47 (2008) 4354.
3). Y. Sato, A. Miyazaki, K. mori, and T. Nakamura: Jpn. J.
Appl. Phys. 46 (2007) 4982.
4). Y. Tanaka, M. Yamagata, and T. sasano: Kogaku 27 (1998)
720 [in Japanese].

1J2a-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 15- 16
11-13 November, 2008

LFB 超音波材料解析システムによる漏洩弾性表面波伝搬特性の測定モデル
Measurement model for propagation characteristics of leaky surface acoustic waves
by the line-focus-beam ultrasonic material characterization system
大津賢治1‡，荒川元孝2，櫛引淳一212(1東北大院 医工; 2東北大院 工）Kenji Otsu , Mototaka Arakawa , and Jun-ichi Kushibiki2 (1Graduate School of Biomedical Engineering,Tohoku Univ.; 2Graduate School of Engineering, Tohoku Univ.)
The line-focus-beam ultrasonic material characterization system can perform material characterization by accurately measuring the
propagation characteristics (viz., phase velocity VLSAW and attenuation αLSAW) of leaky surface acoustic waves (LSAWs) excited on
the water-loaded specimen surface. In the conventional theoretical calculations, water was treated as an ideal fluid and theshear-wave component was not considered for the boundary conditions. In this paper, we studied an exact measurement model of
LSAW propagation characteristics for synthetic silica glass and borosilicate glass, considering the shear-wave component in thewater-loading effect and viscosities of longitudinal and shear waves for both specimen and water. The calculated results for thisadvanced measurement model exhibit dispersion for both LSAW velocities and normalized attenuation coefficient factors. This ismainly caused by the effect of shear-wave component of water.

1. まえがき直線集束ビーム超音波材料解析（line-focus-beamultrasonic material characterization: LFB-UMC）システ
ム1) は，水を負荷した試料表面を伝搬する漏洩弾性
表面波（leaky surface acoustic wave: LSAW）の伝搬特性（位相速度VLSAW，規格化伝搬減衰αLSAW）を高精度に計測でき，材料評価に用いられている．従来の測定モデルでは水を理想流体と仮定し，水の横波の効果を無視していた．本研究ではその効果を測定モ
デルに導入して検討を行ったところ，従来の解析値との間に顕著な差が見られたので報告する．
2. 漏洩弾性表面波の伝搬特性の理論解析モデル
Fig. 1 は水の横波を考慮したLSAW伝搬特性の解析モデルとその新しい概念を示すものであり，基板深さ方向を + z 方向とし， + x 方向に伝搬するLSAWの伝搬解を与える境界条件2) は，水と試料の境界において以下のように表される．
(1)
Tzzs = Tzzw
U zs = U zw

(2)

Tzxs = Tzxw

(3)

U xs = U xw

(4)

ただし，上付き添え字 s は試料（specimen）， w は水（water）のパラメータであることを意味する．
水を理想流体として取り扱う場合，境界条件は式(1), (2)および式(3)において Tzxs = 0 とする 3 式で与えられる．
水の横波の効果に対して考慮しなければな
らない境界条件として式(3), (4)が加わり，これら 4 式を解くことで新しい測定モデルにおける LSAW 伝搬特性が得られる．
ここで複素弾性率は一般に c = c′ + jc′′ と表せ，これに関係する定数は Fig. 1 に示すパラメータにより計算される．ここでは試料として 2 種類の等方性固体，
すなわち合成石英ガラス C-7980 と硼珪酸ガラス--------------------------------------------------------------------otsu@ecei.tohoku.ac.jp

SOLID SPECIMENWATER

MEASUREMENT OFBULK PROPERTIESMEASUREMENT OFBULK PROPERTIES

Vls , α ls , Vss , α ss , ρ s

Vlw , α lw , Vsw , α sw , ρ w

WATER w w
CALCULATION OF
cij , ρLSAW PROPAGATIONCHARACTERISTICSVLSAW , α LSAW

cijs , ρ s

LSAW

SPECIMENFig. 1 New concept of theoretical analysis of LSAW
propagation characteristics.
Table I Bulk propagation characteristics of C-7980. [Refs.[3],[4]]Longitudinal

Shear

Velocity [m/s]5929.133767.62

Attenuation coefficient [m−1]1.1 × 10−16 × f 2

Density [kg/m3]

1.9 × 10−16 × f 2

2199.82

Table II Bulk propagation characteristics of C-7740. [Refs.[3],[4]]Longitudinal
Velocity [m/s]5538.29 + 0.0328 × f
−1

−9

Shear
0.27

3401.95 + 1.53 × f 0.10

Attenuation coefficient [m ] 2.30 ×10 × f
1.82 × 10 −9 × f 1.33
3
Density [kg/m ]2222.48
1.29

Table III Bulk propagation characteristics of water. [Refs.[5]-[8]]Velocity [m/s]Longitudinal

Shear

1491.23

10.5 + 2.42 × 10 −7 × f

Attenuation coefficient [m−1] 2.23 × 10−14 × f 2
3

Density [kg/m ]2.64 ×103 × f 0.48

997.54

C-7740 を取り上げる．試料のバルク音響特性をTable I, II 3, 4) に，水に対するそれをTable III 5-8) にまとめ，これらのデータをもとに，新しい測定モデルを用いたLSAW伝搬特性の数値計算を行った．

3432

4. 検討
従来の理論解析法では水の音響特性については水の縦波音速 Vlw のみを考慮している．そこで，水の負荷効果として水の縦波減衰係数 α lw ，横波音速 Vsw ，
横波減衰係数 α sw の各パラメータが LSAW 伝搬特性に与える影響を数値計算により検討した．考慮したパラメータの組み合わせを Table IV に示す．Case①
は水を理想流体と仮定した従来の測定モデルであり，Case②と①の差が α lw の影響，同様に③と②の差がVsw の影響，④と③の差が α sw の影響を表す．
C-7980 および C-7740 の 2 種類の等方性固体試料に対して周波数特性を求めた．225 MHz における値を Table V に示す．その結果，いずれの試料に対しても水の負荷効果として Vsw および α sw の影響が大きく， α lw の影響は十分に小さいことが示された．
また，Fig. 2 において VLSAW ，α LSAW がともに単調増加の傾向を示したことは，Table III より水の音響イ
ンピーダンスの周波数特性がこの周波数範囲で増加したため，漏洩波が大きくなったと考えられる．
さらに Fig. 1 に示した全てのパラメータを考慮した場合を Case⑤とすると，Case⑤と④の差が試料の吸収減衰 α b による影響を表し，それを Table V に併記した．C-7740 の変化は C-7980 のそれより大きく，
C-7740 のバルク損の特性を反映している．

3430
3428

C-7980

3426
3132
3130

C-7740

3128
3126
100

NORMALIZED ATTENUATION COEFFICIENT

Fig. 2 に 100 ~ 300 MHz における LSAW 伝搬特性の数値計算結果を示す．実線は式(1)~(4)の境界条件を適用し，Fig. 1 に示した全ての成分を考慮した新しい測定モデルの計算値，破線は水を理想流体と仮定した従来の測定モデルの計算値を表す．C-7980 の場合，周波数が増加するにつれて，V LSAW およびαLSAW はともに単調に増加した．従来の方法と今回の方法による数値計算結果と比較すると，225 MHzにおいて VLSAW は 3426.22 m/s から 3428.76 m/s へ
0.07 % 増加し，αLSAW は 0.03896 から 0.03934 へ 1.0 %増加した．また C-7740 の場合も同様の傾向を示し，
225 MHzにおいて，VLSAW は 0.09 % 増加し，αLSAW は
2.9 % 増加した．

LSAW VELOCITY [m/s]3. 数値計算結果

150

200
FREQUENCY [MHz]

250

300

(a) LSAW velocity
0.04300.04250.0420C-77400.04150.04100.0395

C-79800.03900.0385
100

150

200
FREQUENCY [MHz]

250

300

(b) Normalized attenuation coefficientFig. 2
Calculated results of LSAW propagation
characteristics for C-7980 and C-7740. Solid lines denote theresults considering the shear-wave component of water,
broken lines denote the results treating water as an ideal fluid.
Table V Water-loading effect of each parameter on LSAW
propagation characteristics at 225 MHz.
C-7980C-7740Diff.(VLSAW ) Diff.(α LSAW )−5

Diff.(VLSAW ) Diff.(α LSAW )②－①w( αl )−0.19 m/s(−0.01 %)1.5×10(0.04 %)

−0.19 m/s(−0.01 %)2.0×10−5(0.05 %)③－②
w
( Vs )−3.51 m/s(−0.10 %)6.6×10−4(1.70 %)

−3.78 m/s(−0.12 %)6.1×10−4(1.48 %)

④－③
w
(αs )

6.23 m/s(0.18 %)

−3.3×10−4(−0.85 %)6.46 m/s(0.21 %)

−1.6×10−4(−0.40 %)⑤－④( αb )

0.01 m/s(0.00 %)

3.1×10−5(0.08 %)

0.35 m/s(0.01 %)

7.2×10−4(1.76 %)

ことが示された．本研究が測定モデルの完成へ貢献できるものと考える．

5. あとがき
本報では LSAW 伝搬特性の測定モデルにおいて，これまで考慮されていなかった水の横波の効果についてガラスを対象に数値計算を行った．その結果，
得 ら れ た 分 散 特 性 は 水 の 横 波 成 分 が 支 配 的 で あるTable IV Considered parameters as water-loading effect on
calculation of LSAW propagation characteristics.
○: considered, ×: ignored

Case①
Case②
Case③
Case④

Vlw

α lw

Vsw

α sw

○
○
○
○

×
○
○
○

×
×
○
○

×
×
×
○

引用文献
1. J. Kushibiki and N. Chubachi: IEEE Trans. Sonics Ultrason.
SU-32 (1985) 189.
2. J. J. Campbell and W. R. Jones: IEEE Trans. Sonics
Ultrason. SU-17 (1970) 71.
3. J. Kushibiki, R. Okabe, and M. Arakawa: J. Acoust. Soc.
Am. 113 (2003) 3171.
4. 櫛引, 荒川, 鈴木, 小野: 信学技報 US2007-52 (2007) 55.
5. W. Kroebel and K.-H. Mahrt: Acustica 35 (1976) 154.
6. F. E. Jones and G. L. Harris: J. Res. Natl. Inst. Stand.
Technol. 97 (1992) 335.
7. 橋本, 明石, 櫛引: 信学技報 US97-50 (1997) 37.
8. 小林, 明石, 櫛引: 電気学会計測研究会資料 IM-96-89(1996).

1J2a-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 17- 18
11-13 November, 2008

Investigation of carrier recombination processes in GaAs/AlAs
multiple quantum wells using piezoelectric photothermal andsurface photovoltage techniques
光熱分光法と表面光起電力法による GaAs/AlAs-MQW の電子遷移過程の研究
Ping Wang†, Kentaro Sakai, Atsuhiko Fukuyama, Tetsuo Ikari ( Facult. Eng., Miyazaki
Univ.)王萍‡, 境健太郎, 福山敦彦, 碇哲雄 （宮大 工）

1. Introduction

2. Experimental procedure
A high-quality undoped GaAs/AlAs MQW
sample was grown on a semi-insulating (SI) GaAs
(100) substrate by molecular beam epitaxy. The
MQW layer was composed of 50 periods of
12.8-nm-thick GaAs wells and 5.9-nm-thick AlAs
barriers. 2)
For the SPV measurements, the sample was
first mounted on the cold finger as the groundedback electrode with an insulating sheet, and an
indium tin oxide (ITO) film, as a transparent front
electrode, was placed on this sample.1, 3) The
voltage between the ITO film and the cold finger
generated by the photoinduced changes in thesurface potential was detected as a SPV signal.
For the PPT measurements, a disk-shaped
piezoelectric transducer (PZT) was directly attachedto the sample surface using a conducting paste todetect the heat and/or strain generated bynonradiative transitions. The detailed PPTexperimental setup has already been reported. 4, 5)
The subtracted PPT and SPV spectra were
measured at temperature range from 80 to 300K by-----------------------------------------------------------wping@ssp.phys.miyazaki-u.ac.jp

Peak Signal Intensity (arb.unit)

For improving the performance of quantum
structure optical devices, it is important toinvestigate the carrier generation, confinement, andrecombination processes in quantum wells. We havereported that the excitonic and two-dimensional
step-like subband absorptions up to 3rd ordersubband of GaAs/AlAs multiple quantum wells(MQW) were successfully obtained by using thepiezoelectric photothermal (PPT) and the surface
photovoltage (SPV) methods at room temperature(As shown in the insets of Fig. 1).1) We also
concluded that the subtracted SPV signal detected
the photoexcited carriers confined in MQW,
whereas the subtracted PPT signal implies theradiative recombination of carriers in MQW. In thisstudy, we investigate the temperature dependence ofconfinement,
radiative,andnonradiative
recombinations of photoexcited carriers in MQW.

Subtracted signal intensity
room temperature
3LH
3HH
PPT
2HH
1HH
SPV

1.5

1.6
1.7
1.8
Photon Energy (eV)subtracted SPV

1.9

3HH
2HH
1HH

0

160 180 200 220 240 260 280 300
Temperature (K)Fig. 1
Temperature dependence of subtracted SPV
signal intensities at 1HH, 2HH and 3HH peaks. The
insets show the subtracted PPT and SPV spectra atroom temperature from Ref.1.

deducing the background signal from GaAs
substrate.1) The modulation frequency of the
probing light was set at 100 Hz, where the thermal
diffusion length was larger than the sample
thickness.
3. Results and discussion
Figure 1 shows the temperature dependenceof subtracted SPV signal intensities at 1st- (1HH),
2nd- (2HH), and 3rd- (3HH) subband absorptions,
respectively. Since the subtracted SPV implied thecarrier confinement within MQW,1) the carrierconfinement showed the maximum at around 260K,
and then decreased with decreasing temperature. In
this situation, the confined carriers should comeback to the ground states both through radiative andnonradiative recombinations. Figure 2 shows thetemperature dependence of subtracted PPT signal
intensities at same point. The subtracted PPT
spectra indicated the radiative recombination
component of confined carriers in MQW.1) As thetemperature decreased, a significant decrease ofrelaxation process is now in progress.
In conclusion, we had investigate thetemperature dependence of confinement,
radiative, and nonradiative recombinations ofphotoexcited carriers in MQW. As thetemperature decreased, decrease of carrier con-Peak Signal Intensity (arb.unit)

subtracted PPT

3HH
2HH
1HH
0
160 180 200 220 240 260 280 300

Temperature (K)Fig. 2Temperature dependence of subtracted
PPT signal intensities at 1HH, 2HH and 3HH peaks.

1HH
PL Peak Intensity (arb.unit)

radiative recombination component was observed.
Below 220K, the radiative recombination
component showed negative signals. This behavior
should be interpreted as an increase of thenonradiative recombination component in the MQW.
This behavior was remarkable in the higher ordersubband such as 3HH. It is considered as follows.
When the photoexcited carriers in the higher ordersubband relax to the lowest subband, phonons will
be emitted. These phonons can be detected as thenonradiative recombination signals. If thisrelaxation process dominant at low temperature, thenonradiative recombination component will
increase and then subtracted PPT will show thenegative signal at low temperature.
Figure 3 shows the temperature dependenceof photoluminescence (PL) peak intensities
associated with 1HH, 1LH, and 2HH transitions. It
is obvious that the higher subband luminescence of
2HH can only be observed at higher temperature
above 220K. It can be explained that carriers
pohotoexcited in 2nd electron subband first relaxed
to the 1st electron subband emitting with phonons,
and finally recombined radiatively as 1HH PL
signal. This phonon emitting inter-subband
relaxation process may become dominant when thetemperature decreased. These experimental results
also give an additional evidence for the increase ofnonradiative recombination component at low
temperature. Detailed explanation of this1HH 1LH 2HH

1LH

2HH
0

50

100

150

200

250

300

Temperature (K)Fig. 2Temperature dependence of 1HH, 1LH, and
2HH PL peak intensities

finement and increase of nonradiative
recombination were observed. It was found thatthe phonon emitting inter-subband relaxation
was dominant at low temperature.
Acknowledgment
This work was partly supported by a Grant-in-Aid
for Scientific Research from the Ministry of
Education, Culture, Sports, Science and Technology.
The authors wish to thank to Dr. Kenzo Fujiwara of
Kyushu Institute of Technology for supplying highquality samples.
References
1. P. Wang S. Kurayama, A. Fukuyama,Y. Akashi
and T. Ikari: Jpn. J. Appl. Phys. 46 (2007) 6857.
2. K. Fujiwara, N. Tsukada, and T. Nakayama: Jpn.
J. Appl. Phys. 27 (1988) L1832.
3. L. Kronik, and Y. Shapira: Surface Science
Reports 37 (1999) 1.
4. T. Ikari, S. Shigetomi, Y. Koga, H. Nishimura, H.
Yayama, and A. Tomokiyo: Phys. Rev. B 37
(1988) 886.
5. T. Ikari and A. Fukuyama: in Progress in
Photothermal and Photoacoustic Science andTechnology Vol. IV, ed. A. Mandelis and P. Hess(SPIE, Washington, 2000), Chap. 5, p. 145.

1J2a-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 19- 20
11-13 November, 2008

半導体ナノピラーにおける振動モードのピコ秒音響法による観測
Vibrational modes of semiconductor nanopillars
studied by picosecond ultrasonics
佐久間洋宇 1‡，友田基信 1，松田理 1 , 福井孝志 2 , 富岡克広 2 , Oliver B. Wright1(1 北大院工 ; 2 北大院情科研及び量集センター ）Hirotaka Sakuma1‡, Motonobu Tomoda1 , Osamu Matsuda1, Takashi Fukui2, Katsuhiro
Tomioka2 and Oliver B. Wright1 (1Grad. Sch. Eng., Hokkaido Univ.; 2Grad. Sch. Info. and
RCIQE, Hokkaido Univ.)
We investigate the vibrational modes of GaAs nanopillars of hexagonal cross section on a GaAs substrate using an
ultrafast optical technique. The motions of the pillars after excitation with visible light pulses are detected using atime-delayed infrared light pulses. Thickness modes of the pillars are detected in the 10-30 GHz range.

1. はじめに
近年、ナノマテリアルすなわちナノサイズの物質あるいは構造物に対する振動の研究がなされている。例えば、超短パルスレーザーによるピコ秒音響法を用いて非破壊的に、ナノキューブ[1,2]、ナノディスク[3]、ナノロッド[4]の構造の情報がその GHz 振動から解明されている。
本研究では、新しい形のナノ構造、六角形のGaAs ナノピラーに注目する。ピコ秒音響法を用いてこのナノピラーのピコ秒時間領域の反射率測定を行い、固有振動数を得た。今回の実験で用いたナノピラーの振動数は 10 ~ 30 GHz程度である。
ナノマテリアルの~10 GHz オーダーにおける振動の測定方法としては、ピコ秒音響法が最も適切である。他にも固有振動数を観測する方法としてはピエゾ素子を用いた振動数領域での測定方法[5]、ラマン散乱分光法[6]などが考えられるが、~10 GHz の固有振動数に対して、前者は観測可能振動数領域が低すぎ、後者はラマンシフト量が小さすぎ困難である。
2.

試料

本研究では、試料として GaAs(111)B 面基板に有機金属気相選択成長法により作製した六角形の GaAs ナノピラーを用いた。有機金属気相選択成長法とは半導体ウェハ上に堆積した誘電体マスクに予めパターニングを施し、マスク開口部にのみ所望のナノ構造を自在に形成-----------------------------------------------------------loghiro@eng.hokudai.ac.jp

Fig.1 (a), (b) Typical scanning electron
microscope images of GaAs nanopillars takenfrom different angles.

させる半導体結晶成長法である[7]。この試料の特徴としては、ナノピラーは直径 100 ~ 200 nm、
高さ 300 ~ 800 nm、ナノピラーの間隔 200 ~1000 nm で、空間的周期性を持って配置されている (Fig. 1)。
3. 実験
測定は、光源にモードロック Ti-サファイア
レーザーを用いたピコ秒音響法によって行った[1-4]。ピコ秒音響法とは、ポンプ・プローブ法の一種であり、光パルスを２つに分け、1 つの光パルス(ポンプ光)を用いて試料に
GHz-THz の振動を起こし、その振動によって試料に起こった過渡的光反射率変化をもう１つの光パルス(プローブ光)を用いて測定する方法である。実験に用いた光学系を Fig. 2 に示す。ポンプ光、プローブ光の中心波長はそれぞれ 415 nm、830 nm で光パルス幅は 150 fs、繰り返し周波数は 80 MHz（12.5 ns 周期）である。ポンプ光パルスを対物レンズで直径数 μmに集光し、試料に垂直入射する。このとき熱弾性的または変形ポテンシャルによりナノピラ
ー群に振動が励起される。測定されるプローブ

3

10 X Δ R/R

4
2
0
-2
-4
0

200

400

600

800

Time delay (ps)

光の反射率変化は微小なので、ポンプ光パルス
列を、音響光学素子(AOM)を用いて 1 MHz に変調し、ロックイン増幅器を用いてプローブ光の検出信号の中から、この変調周波数成分のみを検出する。この方法によりピコ秒の時間領域
で試料の 10-6 程度の微小な反射率変化が得られる。
4. 結果と考察
様々なサイズのナノピラーに対してデータを取得した。一例として、直径 180 nm、高さ
290 nm のナノピラーの過渡的な光反射率変化
を Fig. 3 に挙げた。0 ps においてポンプ光が当たり、キャリア励起によるプローブ光の急激な反射率変化が起こっている。その後、0 ～400 ps 程度の時間範囲においてナノピラーの振動による反射率変化が観測されている。
そのデータに対して、フーリエ変換を行うことにより Fig. 4 に示すような周波数スペクトルを得た。20 GHz 付近に表れている反射率変化の最も大きなピークについて取得したデータを検証したところ、このピークがとる振動数がナノピラーの直径に反比例しているという特性を得た。これは六角柱断面における動径方向に振動する単ナノピラーモードであることを示唆している。このナノピラー振動の減衰時
間は~100 ps である。また 50 GHz 付近にある
ピークは基板内を伝播する縦波音響波からのブリルアン散乱によるものである[8]。
5. まとめ
私たちは有機金属気相選択成長法を用いて作られた六角形断面の GaAs ナノピラーの振動
モードを励起・検出する実験を行った。ナノピ

Fig. 3 Relative reflectivity change versus thetime delay between the pump and the probe
pulses. The nanopillar has a height of 290 nm
and a width of 180 nm.
Amplitude (Arb. Units)

Fig. 2 Experimental setup for generation anddetection of nanopillar vibrations. AOM:
acousto-optic modulator, PBS: polarizing beam
splitter, NPBS: non-polarizing beam splitter, PC:personal computer, λ/4: quarter-wave plate.

100
80
60
40
20
0
10

20

30 40 50 60
Frequency (GHz)70

80

Fig. 4 Vibrational amplitude spectrum
obtained from the modulus of the Fouriertransform of the data in Fig. 3.

ラーの断面において動径方向に伸縮するモー
ドが立つことを確認した。
今後は今回観測した以外の振動モードを観測する方法、減衰機構の解明、ナノピラーの周期性による連成的な振動の探求を行っていく予定である。
引用文献
1. H. Petrova et al.: J. Chem. Phys. 126(2007) 094709.
2. J. F. Robillard et al.: Phys. Rev. B 76
(2007) 092301.
3. C. Giannetti et al.: Phys. Rev. B 76 (2007)
125301.
4. G. M. Sando et al.: J. Chem. Phys. 127(2007) 074705
5. J. Fujita et al.: J. Vac. Sci. Technol. B 19
(2001) 2834.
6. H. Portales et al.: Phys. Rev. B 65 (2002)
165422.
7. J. Motohisa et al.: Physica E 23 (2004) 298.
8. C. Thomsen et al.: Opt. Commun. 60(1986) 55.

1J2a-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 21- 22
11-13 November, 2008

Surface Excitation of Shear Horizontal Waves
水平すべり波（ＳＨ）波の表面励振
Morio Onoe

(Professor Emeritus, University of Tokyo)

尾上守夫（東京大学名誉教授）

1. Introduction
Shear horizontal (SH) waves guided in a plate
and torsional waves guided in a rod or pipe havebeen widely used in electronic devices forfrequency control and selection and in ultrasonicnon-destructive testing(NDT). The lowest(fundamental) mode of propagation of both types ofwaves is non-dispersive, namely its phase andgroup velocity are independent of frequency, andhence it can propagate for a long distance without
distortion of waveform. This is a desirable feature
for NDT of such elongated objects as beams andpipes.
In previous papers, a new ultrasonic guided
wave testing were presented. 1 - 3) A trappedenergy mode of vibration of a portion underinspection is excited by mode conversion from a
propagating mode. The resonant freqency and Q are
sensitive to such changes in the portion as thickness,
surface corrosion, etc. It can be remotely measured
by reflection of a propagating mode at the boudaryof the portion. Although a higher mode ofpropagatin may be used, the use of thefoundamental mode has a tangible advantage
mentioned above in order to avoid complexity of
intepretation of test results due to waveform
distortion and multiple propagation of plural modesof propagation.
In such an electronic device as ultrasonicdelay line, a transducer is mounted on a side edgeof a plate. A particular mode can be selectively
excited by a design of configuratin of a transducer.
A transducer fully covered the edge can excite only
the fundamental mode. 4) In NDT, however, it isoften required to mount transducers on the surefaceof a plate or a pipe. Transducers on the surface
usually excites plural modes but not selectively asingle mode.
Hence it is important to study a configurationof transducers, which effectively excites a desiredmode, specifically the fundamental mode.
This paper presents an analysis of excitationof SH waves by transducers mounted on the surface
of a plate. A multiple transmission line model
previously used in an analysis of remote excitationof trapped energy mode is also useful in the present
study.
-------------------------------------------------------------e-mail: m.onoe@ieee.org

As previously reported, dispersion curves of
torsional waves in a rod or a pipe, axiallysymmetric waves in a plate and circumferential SH
waves in a pipe are similar to those of SH waves ina plate. Hence the present analysis yield a good
approximation for all these waves, when the
thickness is small.
2. Multiple transmission line model
SH waves in a plate consists of plural modes.
Their dispersion curves are shown in Fig. 1. The
vertical axis is for normalized frequency, thehorizontal axis is for normalized wave number
and m is the order of mode. The fundamental (m=0)
mode is non-dispersive, whereas higher modes are
dispersive. A higher mode has a cutoff frequency,
which corresponds to an overtone resonance ofthickness shear mode in an infinite plate. At afrequency higher than a cutoff frequency, the wave
number becomes real as shown in the right halfplane of Fig. 1 and hence waves can freely
propagate. At a frequency lower than a cutoff
frequency, the wave number becomes pure
imaginary (evanescent) as shown in the left halfplane and hence waves cannot propagate. A tangent
to a dispersion curve in the right half plane yields
group velocity, which is close to zero at near acutoff frequency with severe dispersion.

Fig. 1 Dispersion curves of SH waves in a platePropagation characteristics of each mode canbe represented by a transmission line, based on theforce-voltage and particle velocity-current analogue
as shown in Fig. 2. Frequency response of each line
is also included. Distribution of displacement acrossthe thickness of each mode constitutes a Fourier cos
series, which can expand any distribution. across across section. 4) Specifically impulse excitation at
surface is expanded into impulses of equal
amplitude (like white noise) as input for each line.
Impulse response of each line can be obtained
from frequency characteristics. For any input
waveform, an output waveform of each line after acertain propagation distance can be obtained as a
convolution of input waveform and impulse
response of each line. (Alternatively a product infrequency domain. ) A summation of all the output
as a cosine series yields a whole distribution at thecross section.
If all the frequency components of an input
waveform are below the first cutoff frequency, only
the fundamental (m=0) mode remains and all thehigher modes decay out in the far distance. In order
to excite a trapped energy mode, however, an input
waveform should contain some frequency
components above the first cutoff frequency. These
components propagate in the first (m=1) mode as
well as the fundamental (m=0) mode. But thesecomponents near the cutoff frequency in the firstmode have very small group velocity and also
encounter severe dispersion and hence spread out ina wide time span. Hence only the fundamental
mode remains after some distance of propagation.
Fig. 3 shows output waveforms after
propagation of normalized distance (x = distance/
plate thickness) of 2 and 10, respectively. The input
waveform is a burst sine wave with envelope ofraised cosine starting at the time step of 50. Its
normalized frequency is 0.7 and bandwidth is 52 %.
The output waveform of the fundamental mode is
the same as the input waveform. Output waveformof the first mode at x = 10 shows more spread thanwaveform at x = 2 as expected. Hence, practicallyspeaking, it is possible to generate only thefundamental mode by surface excitation.
Characteristics of a transducer with any
configuration can be calculated from impulse
response. Design techniques of interdigitaltransducer for SAW devices can be utilized torealize more efficient or unidirectional excitation.
References
1. M. Onoe: IEICE Technical Report, US2006-78,(2006). (in Japanese).
2. M. Onoe: Proc. FCS, (2007) pp.488-493.

3. M. Onoe, K. Oka, T. Suzuki: Proc. USE, (2008)
pp.75-80. (in Japanese)
4. M. Onoe: J. Acoust. Soc. Am., 35 (1963) pp.
1003-1008.

Fig. 2 Multiple transmission line modelFig. 3 Output waveforms for x = 2 and 10.

1P1-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 23- 24
11-13 November, 2008

Vibrational Modes in Rectangular Cross-Section
Nanowire Superlattices
矩形断面を持つナノワイヤー超格子に生じる振動モード
Seiji Mizuno† and Yushi Nakamura (Dept. Appl. Phys., Hokkaido Univ.)
水野誠司，中村祐史（北大院工）1. Introduction
Recently, advances in fabrication methods
enablerealizationof
one-dimensional
compositionally modulated nanowires. For example,
GaAs/GaP, Si/SiGe, InAs/InP, and ZnSe/CdSenanowire superlattices (NWSLs) were synthesized,
and their electronic, optical, and transport properties
were studied [1-4]. It has been shown that the
NWSLs offer unique features, which are radicallydifferent from plain nanowires and quantum wells intheir electronic, optical, and transport properties [5].
The NWSLs lead to a variety of possible
applications [6, 7]. Moreover, it is expected that the
NWSLs yield interesting physical effects on phonon
properties.
In previous papers [8, 9], we studied thetorsional modes generated in isotropic NWSLs. In
the present work, we theoretically study all the
acoustic phonon modes in NWSLs composed of"anisotropic" materials. Based on the group theory,
the acoustic phonon modes are classified anddiscussed.

phonon displacements at the corners of therectangular section are shown. These modes are
named as follows: A1 mode is the dilatational mode,
A2 mode is the torsional or shear mode, and B1 andB2 modes are the flexural modes.

)

)

*

*

y

2. Symmetry and vibrational modes
Here, we consider acoustic phonon modes in arectangular cross-section NWSL consisting of cubic
materials [Fig. 1].

xFig. 1. Rectangular cross-section nanowire superlattice.

The point group of the rectangular cross-section
is C2v, whose irreducible representations are A1, A2,
B1, and B2. Using their projection operators, we canconstruct symmetry-adopted basis functions
belonging to the irreducible representations of thisgroup. The symmetries of these basis functions areschematically illustrated in Fig. 2, in which only the†e-mail address: mizuno@eng.hokudai.ac.jp

xFig. 2. Symmetry-adopted basis functions belonging to
the irreducible representations of C2v. Arrows and ±show the phonon displacements at the corners.

3.

y
z

z

Mathematical method

We calculate numerically all the acoustic
phonon modes generated in the free-standing
NWSL with the use of the XYZ algorithm [10].
This method was developed in resonant ultrasoundspectroscopy for deriving the free vibrationalmodes of inhomogeneous objects and later applied
to homogeneous plain wires [11]. We modify thismethod and apply to the present problems.
By solving the elastic wave equation with thesymmetry-adopted basis functions, the dispersion
relations and phonon displacements are obtained foreach phonon mode.

4. Numerical examples
As a numerical example, we consider a NWSL
consisting of the alternate stacking of GaAs andAlAs, i.e. A = GaAs and B = AlAs. The size of thisNWSL is as follows: X = 5 nm, Y = 10 nm, and dA= dB = D/2 = 50 nm (see Fig. 1).
30Frequency (GHz)

25

20

B2
A1

15

A2
10

B1

5

phononic band gaps are generated at the center andedges of the mini-BZ. In the present example, thefrequency gaps of B1 and B2 modes (flexuralmodes) are small compared with the other modes.
5.

Summary

In the present work, we theoretically studied theacoustic phonon modes in a NWSL composed of
cubic materials. Based on the group theory, theacoustic phonon modes were classified. We foundthere exist four independent phonon modes in therectangular cross-section GaAs/AlAs NWSLs.
Using the XYZ algorithm, we calculated dispersion
relations for each mode. The overall structure of thephonon dispersion relations can be understood by
the folding of the dispersion curves in the subband
structure of a homogeneous plain wire. Phononic
band gaps are generated at the center and edges ofthe mini-BZ.
Here, we note that dispersion relations dependon the shape of the cross-section of a NWSL. The
results for square and circular cross-section NWSLs
will be given elsewhere. Furthermore, it would beinteresting to consider a phononic crystal consistingof two-dimensional arrays of NWSLs.
Acknowledgment

0
0

qD

π

Fig. 3. Phonon dispersion relations of the rectangularcross-section nanowire superlattice consisting of GaAs
and AlAs.

The calculated dispersion relations are shown in
Fig. 3. Here, q is the Bloch wave number in the z
direction. The numbers of basis functions used in
the present calculation is empirically selected to be
336 for each mode. These dispersion relations
become complicated structure due to the effects ofboth the confinement of phonons in the lateral
direction and superlattice modulation in thelongitudinal direction. However, the overall
structure of each phonon dispersion relation can beapproximately understood by the folding of thedispersion curves for a homogeneous cylinder into
the mini-Brillouin zone (BZ) determined by theperiodicity D of the NWSL.
Subband structure exists originally in thedispersion relation of the homogeneous plain
nanowire. This is due to the fact that the wave
vectors in the lateral direction are discretizedbecause of the lateral confinement. Each dispersion
curve in this subband structure is folded into themini-BZ. In the folded dispersion relation,

The authors had useful discussion with N.
Nishiguchi.
References
1. M. S. Gudikson L. J. Lauhon, J. Wang, D. C.
Smith, and C. M. Lieber, Nature (London) 415,
617 (2002).
2. Y. Wu, R. Fan, and P. Yang, Nano Lett. 2, 83(2002).
3. M. T. Bjork, B. J. Ohlosson, T. Sass, A. I.
Persson, C. Thelander, M. H. Magnusson, K.
Deppert, L. R. Wallenberg, L. Samuelson, Nano
Lett. 2, 87 (2002).
4. R. Solanki, J. Huo, and J. L. Freeouf and B.
Miner, Appl. Phys. Lett. 81, 3864 (2002).
5. L. C. Lew Yan Voon and M.Willatzen, J. Appl.
Phys. 93, 9997 (2003).
6. M. T. Bjork, B. J. Ohlosson, C. Thelander, A. I.
Persson, K. Deppert, L. R. Wallenberg, L.
Samuelson, Appl. Phys. Lett. 81, 4458 (2002).
7. C. Thelander, T. Martensson, M. T. Bjork, B. J.
Ohlosson, M. W. Larsson, L. R. Wallenberg, L.
Samuelson, Appl. Phys. Lett. 81, 4458 (2002).
8. S. Mizuno, Phys. Rev. B 71, 085303 (2005).
9. S. Mizuno, Jpn. J. Appl. Phys. 47, 3817 (2007).
10. W. M. Visscher, A. Migliori, T. M. Bell, and R.
A. Reinert, J. Acoust. Soc. Am. 90, 2154 (1991).
11. N. Nishiguchi, Phys. Rev. B 50, 10970 (1994).

1P1-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 25- 26
11-13 November, 2008

Electrical Properties of Textured(Bi1/2K1/2)TiO3-BaTiO3 Ceramics
粒子配向型(Bi1/2K1/2)TiO3-BaTiO3 セラミックスの電気的諸特性
Masahiro Nemoto†, Yuji Hiruma, Hajime Nagata and Tadashi Takenaka(Faculty of Science & Technology, Tokyo University of Science)
根本正博†，晝間裕二，永田肇，竹中正 （東理大 理工）

1. Introduction
A (1-x)(Bi1/2K1/2)TiO3-xBaTiO3 [abbreviated to
BKT-BT100x] solid solution attracts attention as a
candidate material for lead-free piezoelectric
actuator applications. In particularly, the BKT-BT(x<0.4) seems to be a considerably promising
candidate material for lead-free piezoelectrics witha wide working temperature range because thedepolarization temperatures, Td, for BKT-BT100x(x=0-0.4) are higher than 300°C. Although theCurie temperature, Tc, decreased with increasing theamount of BT in BKT-BT, the larger anisotropy c/a(~1.025) has been obtained at BT content (x) lessthan 30 mol%.[1] Moreover, BKT-BT10 has arelatively high piezoelectric constant (d33=73.4
pC/N), however, it is not sufficient for use inpractical actuators. For the enhancement of its
piezoelectric properties, the grain oriented
BKT-BT100x ceramics are prepared by a reactive
templated grain growth (RTGG) method.[2-5]Grain orientation processe are superior method
for enhancing piezoelectric properties; particularly,
the
RTGG
is
very
effectiveforperovskite-structured ferroelectrics.[2-5] RTGG
enables us to prepare textured solid solutions,which is difficulty in making single crystals. Grain
orientation process was developed by the growth oftemplate grains at the expense of matrix grains
during sintering. In other words, the growth oftemplate grains is responsible for the texture
development and the grain growth itself is also very
important for obtaining highly textured samples.
In this study, we attempted to prepare
grain-oriented
0.9BKT-0.1BT(BKT-BT10)
ceramics by the RTGG method with long soaking
time (2~200 h) and to investigate their electricalproperties.
2. Experimental Procedure
Textured specimens were prepared by RTGG
with matrix and template of platelike Bi4Ti3O12(BiT) particles for BKT-BT. Platelike BiT particles
were prepared by a molten salt synthesis. Bi2O3 and-----------------------------------------------------------E-mail : tadashi@ee.noda.tus.ac.jp

TiO2 were mixed with an equal weight of salt andheated at 1070~1100°C for 0.5 h. Platelike BiTparticles with an average diameter of about 10-20µm and a thickness of about ~0.4 µm were obtained.
The starting materials for matrix particles wereBaTiO3, Bi2O3, TiO2, and K2CO3 with purities of
3-4 N. Calcined BKT-BT10 powders were preparedby a solid-state reaction. Raw powders were mixed
by ball milling for 10 h with ethanol. Resulting
powders were calcined at 950-1000°C followed byball milling for 20 h.
The reactive template consists of platelike BiTparticles (the template content ≈35 wt %), and thecomplementary compounds (matrix particles) are
BaTiO3, Bi2O3, TiO2, K2CO3, and calcined
BKT-BT10 powder. The slurries for tape casting
were prepared by mixing the starting mixtures,
solvent, binder, and plasticizer. The sheets were cut,laminated, and pressed to form green compacts. The
green compacts were heated to remove organic
ingredients and sintered at 1080°C for 2-200 h.
Moreover, nontextured BKT-BT10 ceramic wasalso prepared by a conventional ceramic fabrication
technique for comparisons with textured ceramics.
These ceramics were cut and polished for physicalmeasurements. The crystal phase of these ceramics
was determined using an X-ray diffractometer(XRD; Rigaku RINT-2000). The orientation factor,F, was determined from the XRD pattern by the
Lotgering method. Microstructures were observed
by a scanning electron microscopy (SEM: Hitachi
S-2400). Electric-field-induced strains were
measured by unipolar driving at 0.1 Hz using acontact-type displacement sensor (Millitron Model
1240).
3. Results and Discussion

X-ray analyses were carried out on the top
surface of the specimen in grain-oriented samples.
All samples showed a single-phase perovskite
structure with a tetragonal symmetry at room
temperature. The density in the textured specimen
increased with increasing the sintering time. The
density ratio to the theoretical density was ~97% fortextured specimens sintered at 1080°C-200 h.
Figure 1 shows the degree of orientation, F, for
textured BKT-BT10 sintered at 1080°C as a

4. Conclusions
BKT-BT10 ceramics were prepared by theordinary solid state reaction and the RTGG method.
The textured ceramics without matrix grains wereobtained by increasing the sintering time to increase
the grain growth. Field induced strains of
BKT-BT10 ceramic were improved by grainorientation. The d33* (=Smax/Emax) increased withincreasing the degree of orientation, F, and reached
267 pm/V at F≈74%. The textured BKT-BT10
ceramic seems to be a superior candidate material
for lead-free piezoelectric ceramics with large strain
and wide working temperature range.
Acknowledgments
The authors would like to thank Toho Titanium
Co., Ltd., for providing high-purity titanium
dioxide powders. This work was supported in partby Grants-in-Aid for Scientific Research (B) (No.
19360302) from the Japan Society for the
Promotion of Science.

Degree of orientation, F [%]80

BKT-BT1060
40
20@ 1080 ºC

0

50
100
150
200
Sintering time [h]Fig. 1 Degree of orientation, F, for textured BKT-BT10
sintered at 1080°C as a function of sintering time.

0

Strain, S [%]0.25

BKT-BT10
F≈74%

0.2

F≈63%

0.15

F≈35%

0.1

F≈53%

0.05

Random(nontextured)@ 0.1 Hz

0
0

20
40
60
80
100
Electric field, E [kV/cm]
Fig. 2 The strain behavior of BKT-BT10 ceramic under
unipolar driving of electric field, E, from 0 to 80 kV/cm.

300
d33* [pm/V]

function of sintering time. The F increased withincreasing the sintering time and almost saturated at
the sintering time for 100 h. The specimen sinteredfor 200 h indicated higher F than 60%.
The F value was closely related to themicrostructure. The grain sizes were increased withincreasing sintering temperatures and longer
soaking times. It is very important to perform longsintering in order to promote the grain growth andimprove the orientation factor. The matrix grains
remained in textured BKT-BT10 sintered at
1080°C-10 h. The presence of matrix grains
reduced the F.[4] At 1080°C-40 h, however, almost
all matrix grains disappeared, and themicrostructure was composed of only template
grains at 1080°C-100 h. The largest F obtained by
100~200 h sintering is caused by the disappearanceof matrix grains.
Figure 2 shows field-induced strains, S, for
textured and nontextured BKT-BT10 in the
direction parallel (//) to the tape stacking direction
at E=0~80 kV/cm. It can be seen that the strain of
the textured specimen was higher than that of thenontextured (random) specimen. The field-induced
strains of BKT-BT10 ceramic were improved by thegrain orientation.
Figure 3 shows the normalized strain d33*(=Smax/Emax) of textured and nontextured BKT-BT10
ceramics as a function of the degree of orientation,
F. The d33* increased with increasing the F. The d33*of the textured BKT-BT10 ceramic (F≈74%) in the
direction parallel (//) to the tape stacking direction
was 267 pm/V at 80 kV/cm.

BKT-BT10

200
100
0
0

20
40
60
80 100Degree of orientation, F [%]Fig. 3 The normalized strains d33* (=Smax/Emax) of
textured and nontextured BKT-BT10 ceramics as afunction of the degree of orientation, F.

References[1] Y. Hiruma, R. Aoyagi, H. Nagata, and T.
Takenaka: Jpn. J. Appl. Phys. 43 (2004) 7556.
[2] T. Kimura: J. Ceram. Soc. Jpn. 114 (2006) 15.
[3] E. Fukuchi, T. Kimura, T. Tani, T. Takeuchi, and
Y. Saito: J. Am. Ceram. Soc. 85 (2002) 1461.
[4] K. Fuse and T. Kimura: J. Am. Ceram. Soc. 89(2006) 1957.
[5] T. Kimura, T. Takahashi, T. Tani, and Y. Saito: J.
Am. Ceram. Soc. 87 (2004) 1424.

1P1-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 27- 28
11-13 November, 2008

Exact Analysis of Lamb Waves in Piezoelectric Membranes with
Distinct Electrode Arrangements
Yung Yu Chen (Tatung University, Department of Mechanical Engineering)

1. Introduction
Piezoelectric membranes have been widelyused in electro-acoustic and microfluidic devices[1-4]. When the membrane thickness is less than awavelength, Lamb wave modes exist and propagate
in the membrane; hence, these devices are so-called
Lamb wave devices. In order to improve theirperformances, the phase velocity dispersion andelectromechanical coupling coefficient (ECC) of
the Lamb wave must be calculated exactly during
designing.
Currently, two methods have been widely used
to calculate the ECC. One is the acoustic velocity
difference method, based on the velocity difference
under free-surface and metalized-surface electicalboundary conditions. Adler [5] adopted this method
to analyze Lamb waves in piezoelectric membranes
with distinct electrode arrangements. However, thisis an approximation method. The other is theGreen’s function method. Joshi and Jin [6] adopted
this method to calculate the ECC of Lamb waves insingle piezoelectric plate; nevertheless, distinct
electrode arrangements were not taken into account.
This paper aims at analylzing exactly Lambwaves in a single piezoelectric membrane with
distinct electrode arrangements. First, a transfer
matrix [5-8] is used to calculate the phase velocity
dispersion. For exact analyses, the Green’s function
method is employed to calculate the ECC under
distinct electrical boundry conditions. Finally, thecalculated results are compared with that by using
the acoustic velocity difference method..
2. The electromechanical coupling coefficient
2.1 The acoustic velocity difference method
The electromechanical coupling coefficient
K S2 of a piezoelectric membrane is obtained
approximately by [6-8]
v vm
(1)
K S2 2 ovowhere vm and vo are the Lamb wave velocity withmetallized and free surface respectively.
2.2 The Gr
e
e
n’
sf
unc
t
i
onme
thod
The electromechanical coupling coefficient
K S2 of a piezoelectric medium is obtained exactly-------------------------------------------------------------yychen@ttu.edu.twby [6-7]( )
K S2 2s ε
(2)
s
( )
where εistheeffective
permittivity
atinfinitesslowness and s is a coupling parameter.

3. Calculation results

ZnO thin films with c axis have been widelyused to configure electro-acoustic devices due totheir high ECCs. Therefore, a ZnO membrane istaken as the calculation example. Moreover, there
are two electrode arrangements, shown in Fig. 1, in
the calculation; the IDTs are deposited on top
surface and the down surface can be either
electrically free or metallized. The metallizationmeans zero potential and no mechanical loading.
Shown in Fig. 2 is the phase velocity
dispersion of the first three Lamb wave modes withfree surface, which was calculated by using thetransfer matrix. This result shows that the firsttwo modes are all-pass modes, but the A2 (second
antisymmetrial) mode is a high pass mode. We notethat except for the A1 (first antisymmetrical) mode,
phase velocity is larger than that of surface wave.
Fig. 3 and Fig. 4 show the ECCs for the freesurface case and metalized surface case calculated
by using the Green’s function method,respectively. Results show that the ECCs
deeplydependsontheelectrodearrangement. Moreover, at most of thefrequency-thickness products, the ECC of the Lambwave is larger than that of surface wave. This is oneof the reasons why the Lamb wave devices attract
increasing attentions recently. It is worth noting that
the ECC of the A2 mode for the free surface caseincreases with decreasing the frequency-thickness
product and is much larger than that of other modes.
However, the dispersions of not only phase velocity
but ECC for this mode are obvious. This will
increase the fabrication difficulty.
Fig. 5 and Fig. 6 show the ECCs for the freesurface case and metalized surface case calculated
by using the acoustic velocity difference
method. Although most of the results is close
to that calculated by us
i
ng t
he Gr
een’
s
function method, the difference exists for theS1 (first symmetrical) mode with metalized
surface. This reminds us to use carefully thecalculated results of the acoustic velocity
difference method during designing eventhough this method is simple.

Conclusions

Acknowledgment
The author thanks the financial support of thisresearch from the National Science Council of ROC
through the grant NSC 97-2221-E-036-020-MY3.
References
1. R.M. White, P.J. Wicher, S.W. Wenzel, and E.T.
Zellers：IEEE Trans. Ultrason. Ferroelectr. Fre.
Control 34 (1987) 162.
2. N. Yamamoto, Y. Nakagawa, and S. Kakio：Jpn.
J. Appl. Phys. 47 (2008) 4024.
3. Y. Nakagawa, M. Momose, and S. Kakio：Jpn. J.
Appl. Phys. 46 (2007) 4665.
4. N.T. Nguyen and R.M. White：Sensor Actuat.
A-Phys. 77 (1999) 229.
5. E.L. Adler：IEEE Trans. Ultrason. Ferroelectr.
Fre. Control 36 (1989) 223.
6. L. Fan, S.Y. Zhang, K. Zheng, W. Lin and H.D.
Gao：Ultrason. 44 (2006) e849.
7. T.T. Wu and Y.Y. Chen：IEEE Trans. Ultrason.
Ferroelectr. Fre. Control 49 (2002) 142.
8. T.T. Wu and Y.Y. Chen：J. Mech. 19 (2003) 225.
IDT

IDT

piezoelectric membranepiezoelectric membrane

free surface

metalized surface(a)(b)
Fig. 1 Two types of electrode arrangements.

A2
S1
A1

8

6

4

2

0

0

fh (m/s)

2000

3000

8

6

A2
S1
A1

4

2

0

0

1000

fh (m/s)

2000

3000

Fig.4 Coupling coefficient for metalized surface
calculated by the Gr
e
e
n’
sf
unc
t
i
onme
t
hod.
10
A2
S1
A1

8

6

4

2

0

0

1000

fh (m/s)

2000

3000

Fig.5 Coupling coefficient for free surface
calculated by the acoustic velocity difference
method.
10

10000

coupling coeffecient (%)

A2
S1
A1

8000

Phase Velocity (m/s)

1000

Fig. 3 Coupling coefficient for free surface
calculated by the Gr
e
e
n’
sf
unc
t
i
onme
t
hod.

coupling coeffecient (%)

This paper proposes a exact analysis of
Lamb waves in the ZnO membrane with two
types of electrode arrangements by theGreen’s function method. By comparing the
calculated results of the two methods, we cansee that the difference indeed exists,
especially for the S1 mode. Moreover, thecoupling coefficients deeply depends on theelectrode arrangement. Results show that
the S1 mode for the metalized surface case is abetter choice for a Lamb wave device due to
its larger velocity, higher coupling coefficientand less dispersion.

coupling coeffecient (%)

10coupling coeffecient (%)

4.

6000

4000

8

6
A2
S1
A1

4

2

2000
0

0

0

1000

fh (m/s)

2000

3000

Fig. 2 Phase velocity dispersion of the first three
Lamb modes with free surface.

0

1000

fh (m/s)

2000

3000

Fig.6 Coupling coefficient for metalized surface
calculated by the acoustic velocity difference
method.

1P1-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 29- 30
11-13 November, 2008

Effect of atmospheric pressure plasma treatment on
ultrasonic bumpless flip chip bonding
Jung-Lae Jo‡, Ja-Myeong Koo, Jong-Bum Lee, Seung-Boo Jung (Sungkyunkwan
Univ. , School of Adv. Mat. Sci. & Eng.) and Jeong-Hoon Moon (Suwon Sci.
College, Dept. of Mechanical Eng.)
1. Abstract
A transverse ultrasonic vibration was
employed to bond the Cu flip chip bump with
Cu finished glass substrate. This study was
focused on the atmospheric pressure plasma
treatment conditions on the ultrasonic bonding
strength between the Cu bump and Cu finishedsubstrate because the cleanness and roughnessof the bonding surface strongly affected the joint
integrity. The optimized ultrasonic conditions
greatly enhanced the joint strength bonded using
ultrasonic energy, while the excessive plasma
treatment degraded the joint integrity. In thisstudy, the mechanisms why the joint strength
was determined by the treatment conditions
were examined and discussed using X-ray
photoelectron spectroscopy (XPS), Auger
electron spectroscopy (AES).
2. Introduction
The miniaturized, multi-functional andportable electronics is realized by thedevelopment of flip chip bonding (FCB)
technology using solder or adhesive.1) Solder
bump connections show high electrical andmechanical properties, while the excessive
growth of intermetallic compounds(IMCs) at thejoint interface significantly degrades theperformance and reliability of the solder joint
during bonding and system operation.2)
Furthermore, electronic devices can experience
heat damage during bonding due to highbonding temperature of conventional lead-freesolders.3) Adhesive bonding methods using
anisotropic conductive adhesive (ACA) or nonconductive adhesive (NCA) furnish shorter
bonding time, lower bonding temperature andfiner pitch than the conventional solder bumps,
but show poor electrical property and low
mechanical reliability.4) Additionally, the thinchip die easily broke off during bonding, due tohigh bonding pressure. Recently, interest in
ultrasonic bumpless flip chip bonding
technology has been growing, due to its
potential advantages such as fast bonding time,

low bonding temperature, low bonding pressure,environment-friendly rocess, high electrical andmechanical performances and good reliability.
However, the joint strength bonded using
ultrasonic vibration is sensitive to roughness andcleanness of the joint surface. The atmosphericpressure plasma cleaning technique is one of themost effective methods to clean the bumpsurface, because of its simple structure, highproductivity and easy configuration of in-line
process. 5) However, plasma cleaning withimproper conditions can do more harm than
good.6) Cu has been used as a good electrodematerial for ultrasonic bonding. The interest in
bumpless flip chip bonding are growing in the
portable multi-media electronics, because of its
advantages such as great thermo-stability,
thinner and lighter, lower resistance and power.
However The Cu oxidizes easily. Therefore, thepurpose of this study is to optimize theatmospheric pressure plasma treatment
conditions, gas and treatment time, forultrasonic bumpless flip chip bonding.
3. Experimental Procedure

Figure 1 shows the cross-sectional
schematic structure of the upper flip chipand lower glass substrate. To fabricate theupper substrate, Si wafers were prepared byforming a 0.1 µm-thick SiO2 layer on thebare Si wafer, after which 100 nm-thick Ti
and 500 nm-thick Cu layers were
subsequently sputtered. The lower substrate
was fabricated with 50 nm-thick Cr and 500
nm-thick Cu layers on glass wafer. The SiO2,
Ti, and Cu layers acted as a passivation
layer, adhesion layer between the SiO2, andCu and interconnection, respectively. Afterthe photolithography process, 64 Cu bumps,
of dimensions 22 (W) x 22 (D) x 11 (H) µm,
were electroplated on the sputtered Cu
surface. After another photolithography
process, the Ti/Cu layers were selectively

etched for the patterning of the Kelvinstructure. Four bonding pads were formed ina package, with sixteen bumps on a pad anda pitch size between bumps of 40 µm. Afterthe lower substrate was fabricated byphotolithography process, the glass wafer
was sputtered with 100 nm-thick Cr and 500
nm-thick Cu, which acted as the adhesion
layer between the wafer and Cu and thebonding pad, respectively. Finally, the upperand lower substrates were diced todimensions of 3 x 3 mm2 and 15 x 15 mm2,
respectively.
The samples were cleaned with different
gases and times using atmospheric pressureplasma treatment equipment (SE Plasma Co.,
Korea). The samples underwent plasma
treatment without wet etching. All tests andanalyses were conducted within 1 hour after
the treatment, because the plasma treatment
effect is continually reduced over time. The
contents and structures of the elements on
the surface after the treatment with different
gases and times were analyzed using Auger
electron spectroscopy (AES: Model 660,
Perkin-Elmer Physical Electronics Inc.).
The contents of copper, carbon and oxygen
were analyzed according to Ar sputteringtime.
The spreading test of de-ionized (DI) water
was conducted on the lower substrate after
the treatment with different gases andtreatment times. The distilled DI water was
dropped on the Cu substrate, the lateralimages were recorded by a spreading angle
analyzer, and then the spreading angle wasmeasured using an image tool program(UTHSCSA, U.S.A.).
The upper and lower substrates weredirectly bonded using an ultrasonic bonder(Fineplacer-Lambda, Germany) after thetreatment with different gases and treatment
times. After bonding, the samples were diesheared using a bonding tester (PTR-1000,
Rhesca Co., Japan), for which the 5 kgf loadcell used in this study was calibrated with a
1 kgf standard weight. The fracture mode
was analyzed with scanning electron
microscopy (SEM) after the die shear test.

To investigate the effect of the plasma
treatment on the Cu surface cleanliness, theelements on the surface underwent
quantitative analysis using AES.
3. Results and Discussion

The joint strength was strongly dependent
on the plasma treatment conditions: gases
and treatment time. Too long treatment
increased the O2 concentration of the Cu
surface, thereby decreasing bonding strength.
This showed that the optimization of thecleaning conditions was important toimprove the bonding strength between Cu
bumps and Cu pad. More studies and results
will be discussed in this presentation.
Acknowledgment
This work was supported by grant No.RTI0403-04 from the Regional Technology Innovation
Program of the Ministry of Commerce, Industry
and Energy (MOCIE).
References
1. H. Maruo, Y. Seki and Y. Unami: Assembly
48 (2005) 72.
2. J.W. Yoon, H.S. Chun, J.M. Koo, H.J. Lee
and S.B. Jung: Scripta Mater. 56 (2007) 661.
3. J.H. Lee, J.H. Kim and C.D. Yoo: J. Electron.
Mater. 34 (2005) 96.
4. H. Maruo, Y. Seki and Y. Unami: Proc.
HDP’04 IEEE, 2004, p. 307.
5. H.M. Ho, W. Lam, S. Stoukatch, P. Ratchev,
C.J. Vath and E. Beyne: Microelectron. Reliab.
43 (2003) 913.
6. Ja-Myeong KOO, Jung-Lae JO, Jong-Bum
LEE, Yu-Na KIM, Jong-Woong KIM, Bo-In
NOH, Jeong-Hoon MOON, Dae-Up KIM, andSeung-Boo JUNG : Japanese Journal of applied
Physics Vol. 47, No. 5, 2008, pp. 4309–4313.

Fig. 1 Schematic diagrams of the upper (a) and lower(b) substrates used in this study.

1P1-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 31- 32
11-13 November, 2008

Effect of bonding parameters on ultrasonic bonding offlexible printed board (FPCB) on glass substrate
Jong-Bum Lee, Jong-Gun Lee, Jung-Lae Jo, Ja-Myeong Koo and Seung-Boo Jung
(Sungkyunkwan Univ., School of Adv. Mat. Sci. & Eng.)

1. Abstract
The purpose of this paper is to find bonding
parameters of electrodes between the glass andflexible printed circuit board (FPCB) using
ultrasonic vibration. The electrodes of FPCB andwere electroless-plated with Sn and the glass
substrate was sputtered with Cu.
The peel strengths of the joints were
investigated with various parameters, such as
bonding pressure and time. This study showed thatthe electrodes between the glass and FPCB weresuccessfully bonded without any adhesive at a lowtemperature during a short time, compared to otherbonding methods: adhesive bonding andthermo-compression bonding.
2. Introduction
As the application of the FPCB on glass(FOG) with anisotropic conductive film (ACF) andnon-conductive film (NCF) to the liquid crystal
displays (LCDs), there are some reliability issues in
the industry such as warpage of glass packages,
interfacial delamination and increasing contact
resistance. Also high cost and low feasibility to fine
pitch application issues still exist1). Ultrasonicbonding process is one of the most suitable bonding
methods, because of its high mechanical andelectrical performance, high reliability, shortprocessing time, low processing temperature andenvironment-friendly process.2) Unfortunately,
however, the literature and reliability data about
ultrasonic bonding of the electrodes between PCB
and glass have rarely been reported. In this study,
therefore, the microstructural evolution andmechanical property of the glass to FPCB joint
bonded using ultrasonic vibration were investigatedwith increasing bonding pressure and time.
3. Experimental Procedure
In this study, the thickness of FPCB and glass
was 18 μm and 1 mm, respectively. The Cu
electrodes of FPCB were electroless-plated with Sn
and the glass substrate was sputtered with Cu.
The FPCB was bonded with glass After wet
cleaning with 10 vol.% H2SO4 solution. The glass†

sbjung@skku.ac.kr (S. B. Jung)†

substrate was fixed using a fixture to prevent
mis-alignment during bonding. The electrodes werebonded with different bonding time and pressureusing ultrasonic energy.
Upon completion of ultrasonic bonding, thesamples were mounted in cold epoxy, ground using
100, 800, 1,200, 1,500 and 2,000-grid SiC papers
through a row of electrodes and polished with 0.3
μm Al2O3 powder. The microstructure of the sample
was observed using scanning electron microscopy(SEM) in back-scattered electron imaging mode
(BEI). Elemental analysis was also carried out
using energy dispersive X-ray spectroscopy (EDS).

In-situ temperature variation during
ultrasonic bonding was measured to investigate
the effect of bonding time. The in-situ NCF
temperature measurement was set up with 500
um-thick k-type thermocouples and athermometer with 500 ms sampling period.

To investigate the effect of bonding
conditions on the bonding strength, the peel test
was carried out at ambient temperature andhumidity. The testing speed and angle were 100
μm/s and 90 °, respectively. The fracture surface
was observed and analyzed using SEM and EDS.
4. Results and Discussion
Figure 1 shows the changes of thetemperature at the interface between the electrodes
during ultrasonic bonding. During ultrasonicbonding at room temperature, the temperaturereached to 317.4 °C and 489.3 °C within 3 and 4 s,
respectively. The electrodes of FPCB were fully
bonded on the Cu metallization on glass substratebecause of highly increased temperature during
ultrasonic bonding.
Excessive ultrasonic energy (long bondingtime and high pressure) caused the glass substrategoing to pieces. This showed that the optimizationof the ultrasonic bonding parameter was important
to improve the bonding strength between them.
More studies and results will be discussed inthis presentation.

Acknowledgment
This work was supported by grant No.
RTI04-03-04 from the Regional Technology
Innovation Program of the Ministry of Commerce,
Industry and Energy (MOCIE).
References
1. J.H. Lee, J.H. Kim and C.D. Yoo: J. Electron.
Mater. 34 (2005) 96.
2. K. Tanida, M. Umemoto, Y. Tomita, M. Tago, R.
Kajiwara, Y. Akiyama and K. Takahashi: Jpn. J.
Appl. Phys. 42 (2003) 2198.

Fig. 1 Temperature rise during 3 and 4 s of ultrasonicbonding

1P1-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 33- 34
11-13 November, 2008

Rheology Measurement of Surfactant Solutions
by Electro-Magnetically Spinning Viscometer
球回転式粘度計による界面活性剤水溶液のレオロジー測定
Maiko Hosoda1†, Hideo Ogawa1, Hiroyasu Nomura1 and Keiji Sakai2(1 School of Science and Engineering, Tokyo Denki Univ.; 2 Institute of Industrial
Science, Univ. of Tokyo.)
細田真妃子 1‡，小川英生 1，野村浩康 1，酒井啓司 2（1 東京電機大 理工; 2 東大生研）

1. Introduction
Ultrasonic spectroscopy is applied to the studyof micro-structure and molecular dynamics ofmaterials through the measurement of thevisco-elastic characteristics in the frequency
domain. The observation of the visco-elasticity at
the lower frequency limit is important as it yields
the fundamental reference of the frequency spectra
observed by the ultrasonic spectroscopy.
In this presentation, we introduce a newexperimental technique to give the fundamental
visco-elasticity of soft condensed materials, which
requires a quite small quantity of samples in adisposable manner. The newly developed
viscometer is thus applicable especially to the
medical field, such as the rheology measurement of
the blood and other body fluids, where the pollution
should seriously be prevented.
2. Electro-Magnetically Spinning viscometerWe describe here the brief account of newly
developed Electro-Magnetically Spinning (EMS)
viscometer. The viscometer has a couple of magnets
attached on the rotator, which applies the rotating
magnetic field. A sample cell is a commerciallyavailable small glass tube with smooth concave
bottom, in which an aluminum sphere with 2 mmdiameter is included and set at the center of themagnets.
The rotating magnetic field causes the induced
current in the sphere, and then the Lorentz
interaction between the magnetic field and thecurrent applies torque to rotate the sphere. The
principle is same as that of the Zimm typeviscometer; however, a metal sphere is set at thebottom of the cell in our method. The idea enables
the rheology observation with non-contact anddisposable manner.
Here, let us consider that the magnetic field isrotating in the horizontal plane and is given in theform, B = ( B0 cos Ωt , B0 sin Ωt , 0) . An induced
electric field, which satisfies rot E = −dB / dt
drives the current in the metal sphere, thatis I = σ E , where σ is the electric conductivity andE=ΩB0( − z cos ωt , − z sin ωt , x cos ωt + y sin ωt ) .
2

Lorentz force F then works on the sphere,
which is⎛ −( x cos ωt + y sin ωt ) sin ωt ⎞
ω B0 2σ ⎜⎟F=( x cos ωt + y sin ωt ) cos ωt ⎟
2 ⎜⎜
⎟
0
⎝
⎠
We can calculate the torque T to rotate thesphere to T = π 3σ B0 R 5Ω / 5 , where R is the radiusof the sphere.
The feature of the Zimm-type viscometer isthat the rotator is floated on the surface of thesample fluid to prevent the rotational friction
between the rotator and the bottom. The system has
been effective to accurately investigate the rheology
especially in the low viscosity region; however,some experimental difficulties still remain: The
surface level of the sample must be adjusted
severely to maintain the stable floating, and wehave to take the effect of the surface visco-elasticity
into account.
In our viscometer, instead, we employed asmall metal sphere as the rotator and completely
immersed it in the sample liquid. Let us consider
the resistant torque applied to the rotating sphere:
One is the viscous effect and the other is therotational friction between the sphere and thebottom of the sample cell.
It is known that the resistant torque applied to
the rotating sphere in the viscous liquid on the flatbottom is proportional to the sphere volume and theviscosity and given by Tr＝(4π / 3) β R 3ωη ,where η is the viscosity, β is the coefficient in theorder of unity. On the other hand, the torque due tothe friction is given by Tｆ＝(8π / 9)αμΔρ gR 4 .
Here, μ is the friction coefficient, Δρ is thedifference between the densities of the sphere andsample liquid, g is the gravity acceleration, and weassume that the radius of the real touching area2

3. Experiment
The torque applied to the sphere is
proportional to the difference in the angularvelocities of the magnetic field ΩB and that of thesphere ΩS, and the shear rate of the flow is linearly
related to ΩS. We can, therefore, obtain the viscosity
depending on the shear rate by measuring ΩSchanging ΩB.

various concentrations and temperatures. Typicalresults are shown in Fig.4 and the detailed analysis
would be given in the presentation.
(ΩB-ΩS) (s-1)

100
10
1
0.1

0.01
0.1

1

ΩS

100

1000
100
10
1
0.1
0.01

3.5

1

10

100

1000

10000

Viscosity (cP)3

ΩS (s-1)

10

(s-1)

Fig.2 Relation between (ΩB-ΩS) and ΩS obtained forvarious viscosities. The viscosities are 5, 10, 50, 100,
500, 1000, 5000 and 10000 cP, respectively, from top
to bottom.

(ΩB-ΩS)/ΩS (s-1)

between the sphere and the bottom is αR (α<<1).
Note here that Tf<Tr holds at the small limit of R.
Therefore, the effect of friction is overcome by theviscosity if we use a sphere with enough small
radius as a rotator. Under the condition of η=1.0
mPa·s, Δρ=2000 kg/m3, α≈1/100, β≈1, and μ≈0.1,
the threshold angler velocity giving Tf=Tr, iscalculated to Ωc=10 s-1 for R=1 mm.
At the steady state, the torque applied to thesphere satisfies the equation of
Tｆ＝(4π / 3) β R 3ηω + (8π / 9)αμΔρ gR 4 .
The torque T is written by the first orderfunction with respect to ω, whose gradient and thex-axis intercept give the information on the viscousand frictional force applied to the sphere,
respectively.

Fig.3 The ratio (ΩB-ΩS)/ΩS obtained for various
viscosities.

2.5
2
1.5
1

1000

0.5

25 C
0

0.5

1
(ΩB-ΩS) (s-1)

1.5

Fig.1 Relation between (ΩB-ΩS) giving the applied
torque and ΩS representing the shear rate.

Figure 1 shows the relation between (ΩB-ΩS)
giving applied torque, and ΩS, obtained for theviscosity standard silicone oil with η=10 mPa·s. As
seen, the data are well fitted by the straight line andthe intercept on x-axis gives the friction force. The
logarithmic plot obtained for variety of viscous
samples is shown in Fig.2.
Figure 3 shows the relation between thegradient (ΩB-ΩS)/ ΩS, which is expected to be
proportional to the viscosity, and the literature valueof the viscosity for different standard samples. The
linearity is well examined as seen, and we conclude
that the system could be used as the viscometerwith high accuracy and reproducibility.
The system is applied for the measurement of
the viscosity of rod-like-micellar solutions at

Viscosity (cP)

0
100

30 C
10

35 C
45 C

1
0.1

1

10

100

1000

Shear rate (s-1)

Fig.4 Shear rate dependence of viscosity obtained for
aqueous solution of CTAB and Sal-Na.

Conclusion
The most remarkable feature of the system isthat EMS viscometer is completely free from thepollution and the advantage would be usefulespecially for the medical use. The system isalready applied for the medical measurement of theviscosity of human blood, and the results would
soon be reported.

1P1-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 35- 36
11-13 November, 2008

Phase Relations and Electrical Properties of the Lead-Free(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 Ternary Systems(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3 三成分系の相関系と電気的諸特性
Yuji Hiruma*, Hajime Nagata and Tadashi Takenaka( Facult. Sci. Tech., Tokyo Univ. of Sci.)
晝間裕二, 永田肇, 竹中正（東京理科大学 理工）

1.

Introduction

Piezoelectrics play an important role in electronic
devices such as actuators, resonators and sensors.
Most of piezoelectric materials were composed of
PbZrO3-PbTiO3 (PZT)-based three component
system. However, lead-free piezoelectric materials
were recently required because of theenvironmental protection. Therefore, lead-freepiezoelectric materials with perovskite structure
have been actively studied.
(Bi1/2Na1/2)TiO3 (BNT), (Bi1/2K1/2)TiO3 (BKT)
and BaTiO3 (BT) are well known lead-freeferroelectric materials with relatively highpiezoelectric activities in the lead-free piezoelectricmaterials. Therefore, the BNT-BKT-BT based
ternary system has attracted much attention for a
candidates of lead-free piezoelectric materials withlarge piezoelectric properties. The Curie
temperatures, TC, of BT, BKT and BNT are 135,
400, and 540ºC, respectively.1 However, thedepolarization temperatures Td of BKT and BNT
are approximately 310 and 185ºC, respectively. In
addition, BNT has the rhombohedral-tetragonalphase transition, TR-T, and the temperature of the
maximum dielectric constant, Tm, at approximately
300 and 340ºC, respectively1. There are somestudies on the electrical properties for BNT-BT,
BNT-BKT, and BT-BKT systems. However, thepiezoelectric working temperatures have not beenclarified yet. To use for piezoelectric devices, it isvery important to clarified the phase transition
temperatures.
Thus, in this presentation, we revealed the phaserelations and piezoelectric properties of the
BNT-BKT-BT ternary system. In particular,
depolarization temperatures have been measured
from temperature dependence of piezoelectric
properties.
----------------------------------------------------------e-mail : hirumay@takenaka.ee.noda.tus.ac.jp

BKT(y)BNBK2:1(x)(1-y)BT-yBKT→BTBKy(1-y)BNT-yBKT→BNKTy
MPB
Tetr

BT(z)

(1-z)BNT-zBT→BNBTzRhomb.
BNT(x)

Fig. 1 Schematic diagram of BNT-BKT-BT
ternary systems.

2.

Experimental

The prepared ceramics of x(Bi1/2Na1/2)TiO3y(Bi1/2K1/2)TiO3-zBaTiO3 are shown in Fig. 1.
(1-y)BNT-yBKT, (1-z)BNT-zBT, (1-y)BT-yBKT,
and the inside of xBNT-yBKT-zBT were named as
BNKTy, BNBTz, BTBKy, and BNBKy:z(x)(y:z=2:1). These ceramics were prepared by aconventional ceramic fabrication process. All
higher than 99.9% purity of carbonates and oxides
were used as starting materials. The crystal
structures were identified by the X-ray powder
diffraction patterns using Cu-Kα radiation. The
phase transition temperatures were determined by
the temperature dependence of dielectric andpiezoelectric properties2. The dielectric properties
were measured using an LCR meter (YHP4275 andWayne Kerr 3440). The piezoelectric properties
were measured by the resonance and antiresonancemethod using an impedance analyzer (HP4294A).
The temperature dependences of the piezoelectric
properties were measured using 33-mode specimens.
In particular, we measured the original sample
holder with accuracy of ±2ºC to measure 33-mode
because it is very difficult to measure accurate
temperature of 33-mode specimens.

3.

Results and discussion
TC
400ºC
Temp.

TC

Td

540ºC

310ºC

Tm
340ºC
300ºC
TR-T
185ºC

BKT
TC

Td

135ºC
BT

BNT

MPB

BNBK2:1(x)Fig. 2 The phase relations of the BNT-BKT-BT system.
0.45

(a)

0.40

90-α [ º]Td [ºC]

220
180
140
100

1.020

(b)

1.015

0.35
1.010
0.30
1.005

0.25
Rhomb.
0.0

MPB

0.1

Tetr.

0.2

c/a

260

0.20

0.3

1.000
0.0

0.1

0.2

0.3

y in BNKTy

Fig. 3 Compositional dependence of (a) depolarization
temperature, Td, and (b) rhombohedral distortion,
90º-α, and tetragonality, c/a, for BNKTx.
200

MPB

300
250

160

200
120
150
80
Tetr.

40
0.3

0.4

0.5

0.6

0.7

0.8

Td [ºC ]d33 [pC/N]

Bysummarizing
the
phase
transition
temperatures of BNBTz, BNKTy, BTBKy, and
the
phase
relationsof
BNBK2:1(x),2-4
BNT-BKT-BT ternary systems were revealed, as
shown in Fig. 2. In this study, the variation in TC for
BNT was not clarified; however, Tm of BNT wasclarified to achieve TC of BT and BKT. Meanwhile,
the Td corresponded to the TC with increasing theamount of BT for BNBTz and BTBKy. The highest
Td of BNBTz was approximately 220ºC. On theother hand, the Td shows approximately 300ºC at
the BKT content of y>0.6 in xBNT-yBKT-zBT.
Figure 3 show the compositional dependence ofTd ,rhombohedral
distortion,
90º-α,
andtetragonality, c/a, for BNKTy. It can be seen that Td
is dependent on 90-α at the rhombohedral side andc/a at the tetragonal side of the MPB composition.
On the other hand, in the case of BTBKy, thevariation in c/a was also similar to Td rather than TC.
The Td and the d33 of BNBK2:1(x) weresummarized in Fig. 4. While the MPB was thehighest d33 value of 181 pC/N, the Td was especially
low temperature of approximately 100ºC. Although
the d33 of the tetragonal side is lower than that of
the MPB, the Td of tetragonal side was much higher
than that of the MPB composition. Therefore,
considering both high Td and d33, slightly thetetragonal side of the MPB composition is the
optimum composition for BNT-BKT-BT ternary
system. Further tetragonal compositions at
Td>250ºC were very difficult to pole fully becauseof high c/a. Therefore, it was very difficult to obtainlarge piezoelectricity by the usual poling process.

100
Rhomb.
50
0.9 1.0

x in BNBK2:1(x)4.

Conclusions
In this study, we clarified the phase diagram of
BNT-BKT-BT ternary systems. Considering both
high Td and d33, slightly the tetragonal side of the
MPB composition is the optimum composition, and
it is considered to be promising candidate forlead-free piezoelectric actuator applications.
5.

Acknowledgment

This study was partially supported by Grants-in-Aid
for Scientific Research (B) (No. 19360302) fromthe Japan Society for the Promotion of Science.

Fig. 4 The piezoelectric constant, d33,
depolarization temperature, Td, of BNBK2:1(x).

andReference
1. J. V. Zvirgzds, P. P. Kapostis, and T. V. Kruzina:
Ferroelectrics. 40 (1982) 75.
2. Y. Hiruma, R. Aoyagi, H. Nagata, and T.
Takenka: Jpn. J. Appl. Phys. 43 (2004) 7556.
3. Y. Hiruma, R. Aoyagi, H. Nagata, and T.
Takenka: Jpn. J. Appl. Phys. 44 (2005) 5040.
4. Y. Hiruma, H. Nagata and T. Takenaka: Jpn. J.
Appl. Phys. 45 (2006) 7049.

1P1-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 37- 38
11-13 November, 2008

Elastic and piezoelectric coefficients of LiNbO3 single crystal- RUS measurement and group theoretical analysis LiNbO3 の弾性・圧電定数計測と群論による解析
Yuki Hayashi1†, Ryuichi Tarumi2 and Masahiko Hirao3(1Department of Eng. Science,
Osaka Univ.; 2Graduate School of Eng., Osaka Univ.; 3Graduate School of Eng.
Science, Osaka Univ.)
林勇気 1†, 垂水竜一 2, 平尾雅彦 3 (1 大阪大学 基礎工; 2 大阪大学 工; 3 大阪大学 基礎工)

1. Introduction
Piezoelectric materials are now used in manykinds of sensors, filters and actuators. In addition,
they are one of the potential candidate materials for
future application to MEMS and/or NEMS devices.
Within the framework of linear approximation, theconstitutive equation for stress σij, strain εij andelectric field Ei can be expressed in the following
form,
σij = Cijklεkl + ekijEk.
Where the fourth and the third rank tensors, Cijkl andekij, are the elastic constants and piezoelectriccoefficients, respectively. Hereafter, we express
them by contractive notations; CIJ and eIJ (I,J =1~6).
From the equation one can see that
piezoelectric materials convert electric field Ei into
Precisemechanical stress σij through eIJ.
measurements of CIJ and eIJ are therefore essential
for designing of devices, especially for the above
mentioned small-scaled devices.
Resonance ultrasound spectroscopy (RUS) is an
attracting method to determine CIJ and eIJ
simultaneously from a single crystal specimen.1-2
Recently, low-temperature CIJ and eIJ of trigonal
crystals (α-SiO2 and langasite) were measured by
the RUS and a notable correlation was confirmed
between the temperature dependences of CIJ andeIJ.3 This can be explained with the internal strains
induced by thermal contraction. LiNbO3 also
belongs to the trigonal class. The low-temperature
CIJ and eIJ, and their connection with internal strains
are, however, still uncertain. In this study, weinvestigate CIJ and eIJ of LiNbO3 single crystal by
RUS from ambient temperature to 6 K and discuss
their temperature behaviors from a grouptheoretical point of view.
2. Experiment procedure
2-1. Crystallography of LiNbO3
LiNbO3 belongs・ to trigonal class with its point
group symmetry of 3m (space group symmetry isR3c).4 The independent elastic and piezoelectriccomponents are C11, C12, C13, C14, C33, C44, e15, e22,
hayasi-y@mbox.me.es.osaka-u.ac.jp

e31, and e33. It has 30 atoms in the unit cell as
illustrated in Fig. 1. The normal vibration modes
can be expressed as a direct sum4, in case of
LiNbO3, is expressed through the three irreducible
representations (A1, A2 and E) as follow,(A1+E)AM+(16A1+13A2+29E)OM.
Where, the subscripts represent the acoustic (AM)and optical (OM) vibration modes, respectively.
The specimen used in this study has arectangular parallelepiped shape with a dimension
Theof 9.97x10.03x10.01 mm3, respectively.
mass-density is 4631.7 kg/m3.

Fig. 1 Crystalline structure and Wyckoff position of
LiNbO3.

2-2. RUS measurements
Complete set of elastic constants CIJ andpiezoelectric coefficients eIJ can be determined by
RUS. The crystal specimen is mounted on a
tripod type of ultrasound transducers.
One
transducer excites ultrasound vibration in thespecimen and the other detects the vibration
amplitude while the input frequency is swept.
Free vibration resonance spectrum is then obtained.
Resonance frequencies are determined byleast-square fitting of resonance peaks to Lorenzfunction. Note that the measurement accuracy ofresonance frequency is usually better than 10-5.
The RUS unit is set in a cryogenic chamber, which
can control the temperature from 4 to 300 K within
the accuracy of 0.1 K.

Fig. 2 Temperature dependence of elastic and piezoelectric coefficients of LiNbO3.
C/m2 for eIJ.

3. Results and discussion
Figure 2 summarizes the temperaturedependence of CIJ and eIJ obtained by RUS. We
observe that all components show monotonic
increase with temperature decreasing.
Solidcurves represent the least square fitting results toVarshni’s function,s
C ij (T ) = C ij (0 ) −.
exp(Θ E − T )Here, CIJ(0) is zero-temperature elastic constant (orpiezoelectric coefficient), which includes zero-point
lattice vibration effect. ΘE can be interpreted as an
Einstein temperature.
Results of the present
analysis are summarized in Table I. We note that
ΘE of two piezoelectric components, e15 and e22, arerelatively small among the CIJ and eIJ and also thatthe temperature coefficients, s, of these components
are extremely small.
Table I
Einstein temperature ΘE (K) and fitting
parameter s of LiNbO3.
C12
C13
C14
C33
C11
ΘE
276.2
328.8
261.0
367.0
252.8
s
10.9
4.7
3.0
0.3
8.5
e15
e22
e31
e33
C44
ΘE
267.92
67.3
57.7
551.2
256.3
s
3.5
0.005
0.002
0.3
0.1

LiNbO3 has positive thermal expansion
coefficients so that thermal contraction occurs at
low temperatures. Since the 3m group does nothave inversion symmetry, internal strains are
expected to occur with the contraction. According
to group theory, internal strains can be expressed asa direct sum of irreducible representations, namely,
superposition of optical-mode phonon type atomic
displacements.
On the other hand, latticedynamics perturbation analysis reveals contributionof the normal displacements on CIJ and eIJ.
Results of the analysis are summarized in Table II,
where we see that E mode internal strain can affectHere, theC11, C12, C14, C44, e15 and e22.

The units are GPa for CIJ andcontributions on e15 and e22 are P1F23 and P2F11,
whereas both A1 and A2 cannot influence thesecomponents. It is therefore reasonable to supposethat the notable properties of e15 and e22 would beoriginated from E type internal strain, whichappears due to thermal contraction at low
temperatures.
Table II Effects of internal strains on elastic constants
CIJ and piezoelectric coefficients eIJ.
A1
A2
E
CIJ, eIJ
C11
F11F11
F11F11
C12
F11F11‐F11F11
C13
F11F33C14±F11F23
C33
F33F33
F23F23
C44
e15
P1F23
e22
P2F11
e31
P3F11
e33
P3F33
-

4. Conclusions
In summary, we have determined the complete
set of elastic constants CIJ and piezoelectriccoefficients eIJ of LiNbO3 single crystal using
resonance ultrasound spectroscopy from ambient
temperature down to 6 K. Most of CIJ and eIJ
showed usual temperature dependence whileslightly peculiar properties are found in e15 and e22.
Group theoretical lattice dynamics perturbation
analysis revealed that the origin would be thethermal-contraction induced E mode internal strain.
References
1. I. Ohno: J. Phys. Earth 24 (1976) 335.
2. A. Migliori: Phys. B 183 (1993) 1.
3. R. Tarumi, K. Nakamura, H. Ogi and M. Hirao: J.
Appl. Phys., 102 (2007) 113508.
4. T. Inui and Y. Tanabe and Y. Onodera: Group
Theory of Crystal Lattice and Its Applications inPhysics (Spinger-Verlag, Berlin, 1996).

1P1-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 39- 40
11-13 November, 2008

Study on viscoelastic properties of polystyrene films by a
QCM-D technique
QCM-D 法によるポリスチレンフィルムの粘弾性評価
Aiko Shirai, 1† Yohei Asano, 1 Masahiro Maebayashi2 and Shinobu Koda1 (1 Graduate
School of Eng., Nagoya Univ.; 2Facult. Agric., Meijo Univ.)
白井愛子 1‡，浅野洋平 1，前林正弘 2, 香田忍 1（1 名大 院工; 2 名城大 農）

1. Introduction
It is very important to know dynamic
properties of polymers in the melting region for the
molding and drawing processes. Extensive works ofbulk plymer have been done. However, theexpermental methods to evaluate the dynamic
properties of films at higher temperatures arelimmited. In this work, we develop a QCM-D(Quartz Crystal Microbalance with Dissipation)1-3
technique operated at higher temperatures andexamine the viscoelastic properties of polystyrene
thin films around glass transition and melting
temperatures.
2. Experimental

QCM-D measurement: the experimental setup
was shown in Fig. 1. A 5 MHz AT-cut quartz was
driven by a signal generator (WF1943, NF
ELECTRIC Instruments). The transducer was
disconnected from a driving circuit by a relay(G6Z-1PE-A, Omron) controlled by a function
generator (FG-272, KENWOOD). The decay curveof the QCM oscillation is recorded on an
oscilloscope (DSO3062A, Agelent). The envelopeof the representative decay curve was shown in Fig.
2. It is shown that when the driving power to thequartz oscillator is switched off at time t = 0, thevoltage over the crystal, U(t), decays as an
exponentially damped sinusoidal:
U (t ) = U 0 e −t τ sin(2πft + φ )(1)

frequency. f and f0 are the resonant frequency inmeasurement samples, and the resonant frequencyof the quartz oscillator, respectively. ∆D is thechange of dissipation. D and D0 are the dissipation
in measurement and dissipation of only quartz,
respectively.
The temperature was regulated by a heater
around the sample cell made of brass involving thequartz crystal. The measurements were carried out
in the temperature range from 25 to 200 °C.
Sample Preparation: Polystyrene (PS) withmolecular weight of 45,000 was purchased fromSCIENTIFIC POLYMER PRODUCTS, INC., andwas used as received. PS films were prepared by acasting method from PS-toluene solutions atambient temperature under air atmosphere. Those
concentrations were 0.3, 0.5, and 1wt %.

Computer

Cell
QuartzOscilloscope
Thermostat
Toroidal coil

Relay

Signal generator

TTL

Function generator

Fig. 1 A schematic illustrationof the experimental setup

where U0 is the amplitude at t = 0, τ is the decay
time constant, and φ is the phase.2 The frequency
when the amplitude of decay curve becomes the
maximum is defined as the resonant frequency f. thedissipation factor D is related to the decay time
constant as
D=

1
π fτ

(2)

For each samples, ∆f (∆f = f- f0) and ∆D (∆D =
D - D0) were measured. ∆f is the change of resonant-----------------------------------------------------------A.Shirai: shirai.aiko@d.mbox.nagoya-u.ac.jp

Fig. 2 An envelope of decay curveReferences
1. M. Rodahl and B.Kasemo: Rev. Sci. Instrum. 67(1996) 9.
2. M. Rodahl and B. Kasemo: Sensors Actuators
B37 (1999) 111.
3. M.V.Voinova, M. Rodahl, M. Jonson and B.
Kasemo: Physica Scripta, 59 (1999) 391.

0
-500
-1000
-1500
-2000
-2500
-3000
-3500
-4000

Run1
Run2
Run3

CoolingHeating
0

50

100
150
T[℃]

200

250

Δｆ [Hz]Fig. 3 Temperature dependence of ∆ffor PS film prepared with 0.5 wt%
solution.

0
-1000
-2000
-3000
-4000
-5000
-6000
-7000
-8000
-9000

0.3wt%
0.5wt%
1wt%
0

50

100
150
T[℃]

200

250

Fig. 4 Temperature dependence of ∆f
of PS films.

600
0.3wt%
0.5wt%
1wt%

500
ΔD ×10 6

The temperature dependence of ∆f wasinvestigated through three heating and coolingcycles for the same sample at a temperature change
rate of 1°C /min and the results shown in Fig. 3. In
the case of the first cycle, a difference in the initialand final ∆f was noticed and it is reasonable toassume that this difference is caused by theevaporation of the residual solvent in the film after
casting. Moreover, the quantity of the evaporated
solvent measured by us counts for 12% of thesample. It was also noticed that this difference isdramatically reduced with increasing the number ofcycles carried out for the same sample, this clearly
indicates that the residual solvent in the films after
casting is almost entirely removed during the firstheating process. Hereafter, we present the results ofthe second cycle.
Figures 4 and 5 show the temperaturedependence of resonant frequency shifts anddissipation for three PS films. The magnitude of ∆fdepends on the concentration of PS solutions. The
glass transition temperature and melting
temperature of polystyrene is around 100°C and
230°C, respectively. In the heating and coolingprocesses, the ∆f at temperature below ca. 100°C in
Fig. 5 shows a very weak temperature dependence
and above this temperature, the absolute value of ∆fdecreases. At the low temperature region, ∆f mainlyreflects the quantity of polymers mounted on thequartz oscillator, that is the thickness of the films.
In this work, the thickness of the PS film preparedwith 0.5 wt% PS solution are roughly estimated as
300 nm. The theoretical study of ∆f and ∆D by
Voinova et al. shows that ∆f and ∆D of polymer
films are expressed by functions of viscosity, shear
modulus, density, and thickness of polymer films.3
Therefore, the changes in viscoelastic properties
contribute to the decrease or increase in ∆f and ∆D.
The ∆D increases above theglass transition
temperature, attains the maximum around 160°C
and then decreases.
The magnitude of ∆D
increases with increasing the PS concentration.
∆D is considered to be due to the increase in the
thickness and in the fluidity.

Δｆ [Hz]3. Results and Discussion

400
300
200
100
0
0

50

100

150

200

250

T[℃]

Fig. 5 Temperature dependence of ∆D
of PS films.

1P1-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 41- 42
11-13 November, 2008

Electromechanical coupling coefficient of semiconducting
piezoelectric crystal measured by Brillouin scattering
Brillouin 散乱法による圧電半導体の電気機械結合係数の評価
Taisuke Yoshida 1†, Takahiko Yanagitani 2 and Mami Matsukawa 1 (1 Doshisha Univ.;2
Nagoya Institute of Technology)
吉田泰祐 1‡，柳谷隆彦 2，松川真美 1 （1 同志社大学; 2 名古屋工業大学）

1. Introduction

2. Measurement of piezoelectric property
In general, piezoelectric properties of acrystal are measured by comparing piezoelectrically“unstiffened” and “stiffened” acoustic wave
velocities, V E and V D 2). Electromechanicalcoupling coefficient k of the crystal is written as k2= 1-(V E/V D) 2. However, in a semiconducting
crystal, VD value cannot be determined bywell-known ultrasonic method below UHF ranges,
such as pulse-echo methods, resonance method, andacoustic microscopy. The ”piezoelectric stiffening”
is caused by internal electric field due topiezoelectric polarization. In the case that acoustic
wave frequency is much lower than the carrier
mobility, the space charge distribution due to thepiezoelectric polarization should be screened by the
carriers, and ”piezoelectric stiffening” does notoccur. Figure 1 shows theoretically estimatedresistivity and frequency dependence of the shear
wave velocities of a ZnO crystal, neglecting carrier
diffusion. As can be seen in the figure, highfrequency measurement above the GHz range isrequired to detemine V D value (black part) in thesemiconducting piezoelectric crystal whose resistivity
is less than 101 Ω·m range. Acurally, VHF acoustic
microscopy suffers from the conductivity in thepiezoelectric measurement for ZnO crystal. 3)
Phonon spectroscopy such as Brillouin scattering
method 4) is suitable for measuring piezoelectric
properties in the semiconducting crystal.
-----------------------------------------------------------mmatsuka@mail.doshisha.ac.jp

ZnO crystal
in this study
100 GHz
Phonon spectroscopy

10 GHzFrequency (Hz)

Semiconducting hexagonal crystals such as
AlGaN, GaN, ZnO have been extensively used fortransistors and LEDs. Electronic and opticalproperties in these devices are strongly affected by
the internal piezoelectric field induced by the strain
at boundary of the heterostructure 1). Therefore, it isimportant to know piezoelectric properties of thesecrystals. In this study, we have demonstrated themeasurement of piezoelectric properties ofsemiconducting ZnO crystal by Brillouin scattering
method.

1 GHz
100 MHz

Pulse-echo method,
Acoustic microscopy

10 MHz
1 MHz
Resonance method

100 kHz
10 kHz -4
10

10-2

100

102

104

Resistivity (Ω·m)
Conductor

Semiconductor
2760

VE

= (cE/ρ)1/2= 27332780

Insulator

2800

Shear wave velocity
(m/s)

VD
= (cD/ρ)1/2= 2829Fig. 1 Theoretically estimated resistivity andfrequency dependence of the shear wave velocities ofa ZnO crystal. White part and black part correspond to
the V E and V D values, respectively.

3. Method
A semiconducting ZnO single crystal(10×10×0.5 mm3, MTI Corporation) was used forthe measurement. Resistivity (dc) of the crystal was
30 Ω·m at room temperature, which was simply
measured using Au/ZnO/Au sandwich structure.
For a-plane hexagonal plate, V E and V D
correspond to the velocity of shear horizontal
waves: propagating along c-axis (V ‖ ) andperpendicular to the c-axis (V⊥), respectively. These
two velocities of in-plane direction qΘA were
measured by reflection induced ΘA (RIΘA)
scattering geometry 5,6) as shown in Fig. 2. Typical
Brillouin spectra are shown in Fig. 3. Peaks around
7.5 GHz and 17 GHz correspond to the scatteringfrom shear phonon and longitudinal phonon which
travel in-plane direction. Acoustic velocities VΘAV ΘA = f ΘAλiΘ
2 ⋅ sin 2Here, the f ΘA is shift frequency, λi is wavelength of

the incident light, and Θ/2 is incident angle. The
Brillouin scattering measurement was performed
using a six-pass tandem Fabry-Perot interferometer(JRS Scientific Instruments) with an Argon ion
laser at a wavelength of 514.5 nm. The laser
power near the sample was 54 mW. We haveconfirmed the heating effect of laser beam was very
few from long time continuous measurements. The
actual diameter of the focused laser beam in thesample was approximately 50 µm.

these velocities was in good accordance with theSmith’s constant (k15=0.26).

Shear wave velocity (m/s)

can be determined from shift frequencies of thesepeaks using following equation.

3300

Experiment (Brillouin scattering)Calculated curve (Smith's constant)Calculated curve (Non-piezoelectic)

3200
3100
3000
2900
2800
2700
-10 0 10 20 30 40 50 60 70 80 90 100

Relative Φ (deg.)

SampleksΘΑ,ks180 ki180
Θ/2

qΘA

q180
Θ/2

Fig. 4In-plane anisotropy of shear horizontal
wave velocity of the ZnO single crystal measured by
Brillouin scattering.

Φ
Mirror

5. ConclusionkiΘA

Fig. 2 RIΘA scattering geometry where Φ is thein-plane rotation angle.
4

Light intensity (a.u.)

10Rayleigh (Reference)

Φ= 0, V
Φ= 90, V⊥
‖

ΘA

fs

3

10

Brillouin(Shear)

Brillouin(Longi.)

2

10

1

10

0

10

0

5

10

15

Shift frequency (GHz)
Fig. 3 Typical Brillouin spectra obtained from theZnO single crystal. Open circle and solid triangle
show the spectra measured at Φ = 0º(V ‖ ), Φ =90º(V⊥), respectively.

4. Results
In-plane anisotropy of shear horizontal wave
velocity of the ZnO single crystal was plotted in Fig.
4. Calculated curve with or without piezoelecity
using the Smith’s constant 7) was also shown.
Measured values of V E and V D are 2738 m/s and2838 m/s, respectively, which almost correspond tothe calculated curve. Error bar of the velocity isapproximately 1.6 m/s. k15 value determined fromWe have succeeded in the simple and local
measurement of electromechanical coupling
coefficient k15 of a ZnO crystal by using Brillouinscattering method. Brillouin scattering enables thesimultaneous measurement of in-plane longitudinaland shear wave velocities at hypersonic frequencies.
Moreover, using a microscope system, we will beable to observe much smaller regions. In case of
low resistivity samples, this technique makes
precise and easy nondestructive measurement of k15
distribution possible.
References
1. O. Ambacher, et. al.: J. Appl. Phys. 87 (2000)
334.
2. B. A. Auld: Acoustic fields and waves in solids(John Wiley & Sons, Inc., New York, 1973) pp.
296-307.
3. T. Tanaka, Y. Ohashi, M. Arakawa, J. Kushibiki,
and N. Sakagami: Proc. Piezoelect. Mater. &Device Symp., (2008) 41.
4. K. Shintani, T. Yanagitani, M. Matsukawa, and T.
Otani: Proc. IEEE Ultrason. Symp., 3 (2004)
1864.
5. J. K. Krüger, J. Embs, J. Brierley and R.
Jiménez: J. Phys. D: Appl. Phys., 31 (1998)
1913.
6. S. Murata, T. Kawamoto, M. Matsukawa, T.
Yanagitani, and N. Ohtori: Jpn. J. Appl. Phys. 46(2007) 4626.
7. R T. Smith and V. E. Stubblefield, J. Acoust. Soc.
Am., 46 (1969) 105.

1P1-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 43- 44
11-13 November, 2008

Shear Mode Piezoelectric Properties of
KNbO3-based Ferroelectric Ceramics
KNbO3 系強誘電体セラミックスのシェアモード圧電特性
Kouhei Hikita†, Yuji Hiruma, Hajime Nagata and Tadashi Takenaka(Faculty of Sience and Technology, Tokyo University of Science)疋田康平，晝間裕二，永田肇, 竹中正

INTRODUCTION
Lead-free piezoelectric materials have recently
been demanded from the viewpoint ofenvironmental protection. Potassium niobate,
KNbO3 (KN), has attracted considerable attention
as a candidate material for lead-free piezoelectric
applications, because the KN single-crystal has alarge piezoelectricity and a high Curie point.[1] The
electromechanical coupling factor, k24 and thepiezoelectric strain constant, d24, in the
thickness-shear mode of the KN crystal show ashigh as 0.88 and 205 pC/N, respectively, which are
the highest among those values of current lead-freepiezoelectrics.[1] In terms of KN ceramic, there are
few reports on the piezoelectric properties [2-3],
because of the poor sinterability and the low
resistivity of KN ceramic. To solve these problems,
the modified processes such as hot-press method,
doping effect, atmosphere control have been carriedout so far. Also, our group have successfully
obtained the dense and non-deliquescent KN
ceramic by the modified conventional ceramicfabrication process in air and it indicated highresistivity enough to be poled under the highelectric field [4]. Then, we reported that the k33 of theKN ceramic was 0.50 [4]. However, the piezoelectric
properties for the thickness-shear mode have notmade enough investigation, even though the KN
single crystal shows large shear mode piezoelectric
properties such as k24 and d24 [1]. In this study,
MnCO3 (0.1 wt%)-doped KN (KN-Mn0.1) ceramic
wes prepared by a modified conventional
processing route in air. Also, the shear modepiezoelectric properties such as k15, d15, and themechanical quality factor, Qm, were investigated forthe dense KN-Mn0.1 ceramic.
EXPERIMENTAL PROCEDURE
KNbO3+MnCO3 0.1 wt % (KN-Mn0.1) ceramic
prepared by the modified conventional ceramicfabrication process[4]. Calcination temperatures
were 600ºC for 4 h as the first stage and 1000oC for
4 h as the second stage. And the final sintering was
carried out at 1047 ºC for 2 h in air.
The density of the sintered sample was measured（東理大 理工）by the Archimedes technique. The sintered sample
was characterized using an X-ray diffractometer(Rigaku RINT2000). For the measurements ofelectrical properties such as dielectric andpiezoelectric properties, the samples were
electroded with sputtered gold. Resistivity wasmeasured with a high-resistance meter (HP 4339B).
The samples were cut and polished into appropriate
shapes for the determination of their piezoelectric
properties in the (15) mode. Specimens for the
piezoelectric measurements were poled in silicone
oil bath heated at 150 ºC. A dc electric field of 5
kV/mm was applied to the samples for 5 min during
the poling. Piezoelectric properties were measured
by the resonance-antiresonance method on the basisof the EMAS standard using an impedance analyzer(HP4294A). The k15 was calculated from theresonance and antiresonance frequencies, using
Onoe’s formula. Also, the k15 was found by the ratio
between fundamental and odd-overtone frequencies,
fr(3)/fr(1), fr(5)/fr(1) or fr(5)/fr(3) on the basis of
EMAS-6005. The free permittivities, ε11T, wasdetermined from the capacitances at 1 kHz of thepoled specimen. The elastic compliance constant,s55E, was calculated from the frequency constant, N15,
and the measured density ρ0. Finally, thepiezoelectric strain constant, d15, was calculated fromk15, ε11T and s55E as follow.

d15 = k15 ε 11 ⋅ s55 ,T

E

RESULTS and DISCUSSION
X-ray diffraction pattern of KN-Mn0.1 ceramic
showed a single phase of perovskite structure withan orthorhombic symmetry at RT. A density ratio of
the KN-Mn0.1 ceramic was higher than 96%. From
the temperature dependence of dielectric properties,
Curie temperature, Tc, was 424oC, which is almost
the same as that of pure KN ceramic [5]. The
resistivity, ρ, of the KN-Mn0.1 is higher than
1012 Ω･cm.
Figure 1 shows the frequency dependence ofimpedance, Z, in the (15) mode for the KN–Mn0.1.
Generally, it is very difficult for the (15) mode toCONCLUSIONS
MnCO3 (0.1 wt%)-doped KNbO3 (KN-Mn0.1)
ceramic was prepared by the modified conventional
processing route. Also, the shear mode piezoelectric
properties such as the electromechanical coupling
factor, k15, and the piezoelectric strain constant, d15,
were investigated for the dense KN-Mn0.1 ceramic.
We first revealed accurate value of the k15=0.50 andthe d15=169 pC/N, respectively, for KN-Mn0.1

90k15=0.50
θmax=77.8

|z|

103

45
Phase, θ (deg)

Impedance , |Z| (Ω)

104

0

θ

102

-45

-90

101
2.4

2.9

3.4
3.9
Frequency, f (MHz)

4.4

Fig. 1 Frequency dependence of impedance, Z, in the(15) mode for KN-Mn0.1.
90

104

45
103

0

|z|

102

fr(3)

fr(1)

θ

Phase, θ (deg)

Impedance , |Z| (Ω)

show a good resonance and anti-resonancecharacteristic without spurious peaks because of the
thickness errors. As can be seen in Fig. 1, there aresome spurious peaks in the impedance, |Z|, andphase, θ. The sample shape in Fig. 1 is a rectangularplate with 0.5×3×8 mm3. The length of the poling
direction is l=8 mm and the thickness of the shear
mode is t=0.5 mm. When we changed the sample
dimensions, longer l minimized the intensity of
spurious peaks without arrows in Fig. 1. From thisresult, the frequencies with arrows seem to be theresonance and antiresonance frequencies of the (15)mode. Also, spurious peaks may relate to the lengthof the poling direction. It is still unclear for theorigin of the spurious peaks, so that further studies
are required. Anyhow, the k15 was calculated using
the frequencies with arrows and the value was
k15=0.50. To confirm the accuracy of the k15 value,
we checked this value from the ratio between
fundamental and odd-overtone frequencies, fs(3)/fs(1),fs(5)/fs(1) or fs(5)/fs(3) on the basis of EMAS-6005.
Figure 2 shows frequency dependence ofimpedance, Z, in the (15) mode for KN-Mn0.1 withwide frequency range. The fundamental frequency,f(1), third and fifth harmonics, f(3) and f(5) can beclearly observed. The k15 values from f(3)/f(1) andf(5)/f(3) were 0.48 and 0.50, respectively, which were
almost consistent with that from calculated byresonance and antiresonance method. Additionally,
we compare the k15 value with those from the KN
single crystal. Considering the k15 (0.44) and k24(0.88) in the KN single crystal [1], the k15 value inthe ceramic places to the mean value between k15
and k24 in the single crystal. From these
considerations, the k15 of 0.50 is thought to bereasonable.
Table I summarized piezoelectric properties of
KN-Mn-0.1 ceramic. The relative free permittivity,
ε11T/ε0 was 544, which was larger than the non-poleddielectric constant, εr, (=468). Piezoelectric strain
constant, d15, was 169 pC/N which is lager becauseof large ε11T/ε0 (544) and s55E (24.1 pm2/N). The
shear mode vibration of KN-Mn0.1 ceramic seems
to be a considerably promising candidate for
actuator and high power applications.

-45

fr(5)

101

-90
1

4

7
10
13
Frequency, f (MHz)16

19

Fig. 2 Frequency dependence of impedance, Z, in the(15) mode for KN-Mn0.1 with wide frequency range.
Table I Piezoelectric properties of KN-Mn0.1 ceramic.
N 15
d 15
s 55E
k 15
Qm
ε11T /ε0[Hz·m] [pC/N] [pm2/N]
132
544
0.50
1798
169
24.1

ceramic in this study. The shear mode vibration of
KN-based ceramics seems to be a considerably
promising candidate for actuator and high power
applications.
ACKNOWLEDGEMENTS
This study was partially supported by
Grants-in-Aid for Scientific Research (B) (No.
19360302) from the Japan Society for the
Promotion of Science.
REFERENCES[1] S. Wada, A. Seike, and T. Tsurumi: Jpn. J. Appl.
Phys. 40 (2001) 5690.
[2] T. Yoshida, Y. Hiruma, R. Aoyagi, H. Nagata, andT. Takenaka: Key Eng. Mater. 301 (2006) 19.
[3] H. Matsumoto, Y. Hiruma, H. Nagata, and T.
Takenaka: Jpn. J. Appl. Phys. 45 (2006) 4479.
[4] H. Nagata, T. Hirosue, K. Matsumoto, Y. Hiruma
and T. Takenaka, Jpn. J. Appl. Phys. 46 (2007) 7084.

1P2a-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 45- 46
11-13 November, 2008

Evaluation of Synthetic Silica Glasses by the UltrasonicMicrospectroscopy Technology
+.
/





$

!&'Mototaka Arakawa†, Hideki Shimamura, and Jun-ichi Kushibiki(Graduate School of Engineering, Tohoku Univ.)(†,)#"% -0*

1. Introduction
We have been developing an evaluation method ofglass materials by the ultrasonic microspectroscopy(UMS) technology. Variations in acoustic properties,
viz., bulk-wave velocities, leaky surface acoustic wave
(LSAW) velocity VLSAW, and density , caused by small
amounts of impurities, such as hydroxyl (OH) and
chlorine (Cl), were detected by applying the UMS
Various physicaltechnology to silica glasses1).
properties of glasses depend on the fictive temperature Tf
that is a representative parameter related to the thermal
history.2, 3) In this paper, relationships among acoustic
properties, Tf, and Cl concentration C(Cl) are discussed.
2. Specimen
Specimens were prepared from commercial silica
glasses (ED-B and ED-C, Nippon Silica Glass Co. Ltd.)
manufactured by the vapor phase axial deposition (VAD)
method. Three specimens A, B, and C were preparedfrom the different lots of each glass. Impurities of theglasses were less than 10 wtppm except for OH and Cl
from the catalog.
3. Results
LSAW and bulk-wave velocities were measured by
the line-focus-beam and plane-wave ultrasonic material
characterization system.4, 5) Density was measured by
the Archimedes method.
OH concentration wasmeasured by FT-IR6), and C(Cl) was measured by X-ray
fluorescence analysis.
Measurement results of longitudinal velocities Vl,
shear velocities Vs, , VLSAW, and C(Cl) were summarizedin Table I. Measurement errors were within ±0.11 m/s,
±0.09 m/s, ±0.05 kg/m3, ±0.32 m/s, and ±100 wtppm,
respectively. Velocity dispersions were not observed
for bulk velocities measured in the VHF range. OH
concentrations were 0 wtppm for all specimens.
Maximum differences among specimens were 7.86 m/s
for Vl, 11.75 m/s for Vs, 8.17 m/s for VLSAW, and 0.48kg/m3 for . Maximum difference of C(Cl) was 460
wtppm among the ED-C specimens.
The differencesof acoustic properties among the ED-B specimens could
be caused by the difference of Tf, and those among the
ED-C specimens could be caused by the differences inboth Tf and C(Cl).
--------------------------------------------------------------------E-mail: arakawa@ecei.tohoku.ac.jp

4. Discussion
The relationship between  and Tf was obtained fromrefs. 2 and 3 as follows.

 = 0.0094  (Tf - 1132) + 2202.93(1)

Tf of ED-B(A, B, C) were obtained as 1038°C, 1085°C,
and 1083°C, respectively, by substituting the densities
into eq. (1).
The relationships between acoustic
The
properties and Tf were shown in Fig. 1.
sensitivities of the acoustic properties to Tf were shownin Table II.
The resolutions to Tf were also shown in
Table II, where the measurement accuracies of Vl, Vs,
VLSAW, and  were ±0.1 m/s, ±0.1 m/s, ±0.3 m/s, and ±0.1
kg/m3, respectively.
C(Cl) dependence of density was determined in ref. 3
as follows.

 /T f = {2.44 C (Cl) + 9.10}  103

(2)

The sensitivity of density to C(Cl) was obtained as -2.64(kg/m3)/wt% by substituting Tf of ED-B(C), 1083°C, intoeq. (2).  of ED-C(A, B, C) were calculated from thesensitivity,  of ED-B(C), and C(Cl) of ED-C (A, B, C).
Tentative Tf were obtained using eq. (1) by comparing
the measured and calculated densities.
Then,sensitivities of Vl, Vs, and  to C(Cl) and Tf of ED-C(A,B, C) were obtained with the least squares method for themeasured results of ED-B(C) and ED-C(A, B, C).
The
results are shown in Fig. 2. Tf of ED-C(A, B, C) were
estimated as 1111°C, 1112°C, and 1114°C, respectively.
The sensitivities and resolutions to C(Cl) by acoustic
property measurements were shown in Table II. Vl has
highest resolutions for both Tf and C(Cl).
5. Summary
In this paper, relationships among acoustic properties,
fictive temperatures, and chlorine concentrations werediscussed for silica glasses.
Hereafter, we will
investigate relationships between the acoustic properties
and OH concentrations.

Acknowledgements
The authors are very grateful to H. Sudo and M.
Kudo of Nippon Silica Glass Co. Ltd. for preparation of
the specimens, Dr. Y. Kimura of Research Institute ofElectrical Communication, Tohoku University, forTable I. Acoustic properties at 23°C and Cl concentrations for synthetic silica glass specimens.

Vl
Vs
VLSAW
C(Cl)
Specimen[kg/m3]
[m/s]
[m/s]
[m/s]
[wtppm]ED-B (A)
2202.01 5957.15 3768.31 3429.69
0ED-B (B)
2202.46 5964.84 3764.60 3428.26
0ED-B (C)2202.44 5965.01 3764.66 3428.33
0ED-C (A)
2202.49 5959.39 3756.56 3421.52
1740
ED-C (B)
2202.24 5961.50 3758.29 3423.30
1390
ED-C (C)2202.29 5961.89 3758.52 3423.59
1280
5970

5970
(a) LONGITUDINALVELOCITY
B(C)
5960
C(B)
C(A)
C(C)
5955

(a) LONGITUDINAL
5965
VELOCITY
CB
5960

3765
3435
3760

DENSITY [kg/m3]

3770
5950
3765

(b) SHEAR VELOCITY

3760
3755
3430

(c) LSAW VELOCITY(c) LSAW VELOCITY

3425

3425
2203
(d) DENSITY
2202

2201
1020 1040 1060 1080 1100
FICTIVE TEMPERATURE [°C]

Fictive temperature dependences of acoustic
properties of ED-B specimens.
Table II.

Vl
Vs

VELOCITY [m/s]3770 (b) SHEAR VELOCITY

3430

Fig. 1.

A

3775
5950

VLSAW


DENSITY [kg/m3]

VELOCITY [m/s]

5955

5965

3420
2203
(d) DENSITY
2202

2201

0
500 1000 1500 2000
Cl CONCENTRATION [wtppm]

Fig. 2. Cl concentration dependences of acoustic
properties of synthetic silica glass specimens.

Sensitivities and resolutions to fictive temperature and Cl concentration for synthetic
silica glasses by acoustic property measurements.
Tf
C(Cl)Sensitivity
Resolution
Sensitivity
Resolution
5.99°C/(m/s)
0.6°C-164 wtppm/(m/s)
16 wtppm-12.7°C/(m/s)
1.3°C-320 wtppm/(m/s)
32 wtppm-33.4°C/(m/s)
10°C-339 wtppm/(m/s)
102 wtppm
106°C/(kg/m3)
11°C-4116 wtppm/(kg/m3)
412 wtppm

measurements of OH concentrations. This work waspartially supported by a Grant in Aid for the GCOE
Program.
References
1. J. Kushibiki et al.: J. Appl. Phys. 87 (2000) 3113.
2. J. E. Shelby: J. Non-Cryst. Solids 349 (2004) 331.

3. H. Kakiuchida et al.: Appl. Phys. Lett. 86 (2005)
161907.
4. J. Kushibiki et al.: IEEE Trans. Ultrason.,Ferroelect., Freq. Contr. 49 (2002) 827.
5. J. Kushibiki and M. Arakawa: J. Acoust. Soc. Am. 108(2000) 564 .
6. K. M. Davis et al.: J. Non-Cryst. Solids 203 (1996) 27.

1P2a-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 47- 48
11-13 November, 2008

Thermal diffusivities of high polymer transparent films
investigated by laser induced thermal wave probing
レーザ熱波プローブによる高分子透明膜の熱拡散率の推定(1 blank line)

Yoshiaki Tokunaga, Hiroyuki Kobayshi †and Koji Aizawa ( Kanazawa Inst. Tech)
得永嘉昭，小林弘幸‡，會澤康治 （金工大）(2 blank lines)

1. Introduction
Recently, remarkable attention of the industrial
and academic fields is transiting fromcharacterization of solid material such as a ceramic
or a single crystal to characterization of highpolymer transparent films such as poly (ethylene
terephthalate) (hereafter called PET) ,polyimide（ hereafter called PI ） and poly(vinylidene
fluoride) (hereafter called PVDF).
Since 1989,
we have developed a scanning photo-acoustic
microscope (hereafter called SPAM) and studiedmaterial characters using it [1-2]. Although our
SPAM can be used to the characterization of bulk
materials, unfortunately it cannot be done to thoseof these films [3-5]. The main goal of our present
research is to develop a multi-purpose type of laser
induced thermal wave microscope (hereafter called
LITWM) which can be fully used for these films
and bio materials. As a first step to develop, we
intend to develop measurement technique ofthermal diffusivity of the high polymer transparent
film.
Actual thermal diffusivity, α, may bedifferent remarkably with a value estimated fromphysical parameters of film published by makerbecause it depends strongly on the crystallization
temperature, mechanical stress, casting solvent,electric field and other conditions. In this paper
we describe the experimental results on values ofthe α of high polymer transparent films measured
by our proposed method.
2. Sample preparation and Experimental Setup
Figure 1 shows a photograph of our experimental
sample and a principle of measurement,
respectively [6]. We employed a carbon material(Touyoutanso Co.Ltd. , ISEM-3) as a black
substrate. The representative dimension of thesubstrate was 1.0cm×1.0cm×0.5cm.
Figure 2 shows an illustration of the experimental
setup. A CW laser (Spectra Physics Co. Ltd.
model 127) at the wavelength of 632 nm was used
as an energy source. The laser power and the-----------------------------------------------------------toklab@mlist.kanazawa-it.ac.jp

beam diameter at the irradiated surface were about
9 mW and 300 μm, respectively. The laser light
was modulated by using an acousto-optic modulator(Hoya Co.Ltd, A-100). A microphone (RION
Co.Ltd, NC53A) was used for detecting the PA
signal.
A digital oscilloscope (Iwatsu-Lecroy
Co.Ltd, LC6840) was used for the observation of
the detected signal and signal processing.

Fig.1 Principle of measurement

Fig.2 LITW microsocpe

3. Experimental results and discussion
Our method has advantage in that the α can be
estimated simply by obtaining a relation of phasedifference of the LITW signal generated on thesubstrate with transparent film or without it.
Figure 3 shows an experimental result on arelation of surface temperature, θ, and f whenthe 28-μm-thick PVDF film is used. In this case,the d/μ0 values of 1.2 and 2.0 correspond tomodulation frequency of about 49 and 130 Hz,
respectively. From a slope of solid line by a leastsquare fitting, we can calculate value of the α andobtain value of 3.9×10-8 m2/s. Figure 4 shows anexperimental result on a relation between θ and f
in the film with the thickness of 52 μm. In thiscase, the modulation frequencies corresponding thethermal diffusion length from μ0=42 to 26 μm wereabout 14 to 36 Hz. The value of the α evaluatedfrom a slope of solid line in this region was about
3.4×10-8 m2/s.
μ 0 =23 [ μ m] μ 0 =14[ μ m]

Phase θ

[rad]

0

-2 π
5

6
7
8
9
10 11 12Modulation Frequency √f [Hz 1/ 2 ]Fig.3 Relation between θ andf in the 28μm.

μ 0 = 42 [ μ m] μ 0 = 26[ μ m]

Table I shows representative data on measured
films. In this table a symbol “ d ” represents film
thickness of polymer.
Table I. Measured results of α on various films
filmd[μm] α [m2/s]
Company-8PVDF
28
3.9×10Tokyo Sensor
-8
PVDF
52
3.4×10Tokyo Sensor
-7
PET
100
1.25×10
Teijin Chemicals-7PI
25
1.29×10
DuPont Toray-7
Araldite54
1.13×10
Cemedine

4. Conclusions
We described the experimental results on valuesof the α of high polymer transparent films such as
PVDF, PET, and PI measured by our proposed
method.

0Phase θ[rad]Acknowledgements
This work was partially supported by a
High-Tech Research Center Project Grant.

-π
3

4
5
6
7
Modulation Frequency √f [Hz 1/ 2 ]Fig.4 Relation between θ andf in the 52μm

The measured values of the α in the 28 and
52-mm-thick PVDF film were fairly closed to thepredicted value evaluated indirectly from
representative parameters of the PVDF polymer
published by production maker [7].
Figure 5 shows an experimental result on arelation between θ and f in the PET film. From
this result we could get the α =1.25×10-7 m2/s. Thisvalue was also closed to the predicted one evaluatedindirectly from maker’s publication parameters [8].
μ 0 = 86 [ μ m] μ 0 = 48[ μ m]

Phase θ[rad]0

- π /2
1

2
3
4
Modulation Frequency √f [H z 1/ 2 ]Fig.5 Relation between θ andf in the PET film

References1). Y. Tokunaga, A. Minamide, K. Tamura and S.
Teraoka: Jpn. J. Appl. Phys. 29(1990) Suppl
29-1 283
2). Y. Tokunaga and A. Minamide : Jpn. J. Appl.
Phys. 31(1992) Suppl 31-1 149
3). Y. Tokunaga, A. Minamide, K. Tamura and N.
Nakada : Jpn. J. Appl. Phys. 32 (1993) 2573.
4). Y. Tokunaga, A. Minamide, K. Tamura and N.
Nakada : Jpn. J. Appl. Phys. 33 (1994) 3246.
5). Y. Tokunaga, A. Minamide, and N. Nakada : Jpn.
J. Appl. Phys. 34 (1995) 2900.
6). Y. Tokunaga, M. Imai, M. Suzuki and A.
Minamide : J. Acoust. Soc. Jpn, 63 No.5 (2007)
262[in Japanese].
7). KYNAR PIEZO FILM TECNICAL MANUAL(1987).
8). K. Yugi : Saturated polyester resins handbook.
Nikkan Kogyo Shimbun ,LTD. (1989)233. [inJapanese]

1P2a-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 49- 50
11-13 November, 2008

Copper precipitation process of thermally aged
Fe-Cu alloys evaluated by EMAR method
電磁超音波共鳴法による熱時効 Fe-Cu 合金の Cu 析出挙動評価
Yasuhiro Kamada1†, Shigehiko Chigusa1, Toshihiro Ohtani2, Hiroaki Kikuchi1 andSatoru Kobayashi1 (1 Faculty of Eng., Iwate Univ.; 2Shounan Insitute of Technology)
鎌田康寛 1‡，千種成彦 1, 大谷俊博 2, 菊池弘昭 1, 小林悟 1 （1 岩手大工; 2 湘南工科大）

1. Introduction
It is known that Cu-rich precipitates are oneof the origins of the irradiation embrittlement of
nuclear reactor pressure vessels (RPV) steels [1–3].
The clarification of the degradation mechanism andthe development of nondestructive evaluation(NDE) techniques are important for prolonging the
lifetime of present nuclear power plants. Ultrasoniccharacterization is one of the candidates of NDE
methods and several studies have been reported [4,5]. Although ultrasonic velocity and attenuation
seem to be promising parameters, there has been
little discussion on the effect of Cu precipitation.
Moreover, most of the previous studies were carriedout using conventional ultrasonic techniques using
a piezoelectric transducer that inherently includes
contact problems. In order to clarify the irradiation
effects, precise measurement is necessity tosuppress data scatter and improve reliability.
Recently, an electromagnetic acoustic resonance(EMAR) method, a contactless measurement,
attracts much attention in precise ultrasoniccharacterization [6, 7]. The purpose of this study is
to investigate the copper precipitation process ofthermally aged Fe–Cu model alloys, simulating theirradiation embrittlement of RPV steels, by EMAR
method.
2. Experimental Procedure
The specimens of Fe–1wt.%Cu model alloy
were quenched from 1123 K for preparing thesupersaturated solid solution state. They were
thermally aged at 773 K and the aging time wassystematically varied. In this study, plate-shaped
specimens (L1 × L2 × L3 = 12.1 mm × 11.5 mm ×
2.0 mm) were used. Figure 1 shows the setup for
EMAR measurement and the specimen orientations.
The specimen is inserted into the exciting anddetecting coils located between the magnets. In thecase of ferromagnetic metals, elastic waves are
excited by dynamic magnetic fields from an RF
burst current through the magnetostriction
mechanism [6]. The signal of the excited vibration
was detected by the coil and pre-amplified.
Amplitude and phase information of the signal wereacquired by a personal computer through analog
superheterodyne processing. All the abovemeasurements were carried out using a RITEC
RAM system at room temperature. For anotherseries of specimens, the dependence of hardness
and conductivity on aging time were also measured
at room temperature.
Superheterodyne Data
PC
spectroscopy
ControlPreampRf burst
SignalCoils
Magnets

N

S

S

N

L3
Specimen
Fig. 1
setup.

3.

L1

L2

Schematic representation of the measurement

Results and Discussion

Figure 2 shows the aging time dependence of
the Vickers hardness [8], conductivity, and a typicalresonant frequency of the Fe–1wt.%Cu specimen.
Hardness of the alloy initially increased withincreasing aging time, but started to decrease after
103 min aging (Fig. 2 (a)). This peaking trend was
directly caused by the change of Cu precipitatesstate, formation, growth, structural transformation,and coarsening [8, 9]. On the other hand,
conductivity of the alloy gradually increased withincreasing aging time and approached to the valueof pure iron at the longer aging time (Fig. 2 (b)). It
has been reported that the conductivity of Fe–Cu
alloys in a solid-solution state decreases linearlywith Cu content due to the electron scattering by Cu
solute atoms [10]. This characteristic suggeststhat the observed change of conductivity would be a
result of matrix solute depletion by thermal aging.
The resonant frequency also increased withincreasing aging time, and did not decrease even

after long-time aging (Fig. 2 (c)). This trend issimilar to the change of conductivity caused by adepletion of Cu solute atoms in the matrix. The
resonant frequency is related to the elastic constantof the specimens. Therefore, the similarity of thetrend indicates that the elastic constant of aged
Fe–Cu alloys correlates to the state of solute atoms,
not to that of precipitates. According to the firstprinciples calculation, the elastic constant of bcc
Fe–Cu alloys are smaller than that of bcc Fe, and it
increases with decreasing Cu content [11].
Therefore, the observed behavior of resonancefrequency is attributable to the increase of theelastic constant of the matrix due to Cu solutedepletion during copper precipitation process.

Vickers hardness, HV

200(a) Vickers hardness

180
160
140
120
100

0
-1

9.5

Conductivity,  / 10 Sm

10.0

6

10.5

10

0

10

1

10

2

10

3

10

4

(b) Conductivity
pure Fe

9.0
8.5
8.0

RT

7.5
7.0
6.5

0

0.668

10

0

10

1

10

2

10

3

10

4

10

3

10

4

Frequency, f / MHz(c) Reasonant frequency
0.667

0.666

0.665

0.664

0

10

0

10

1

10

2

Aging time, t / minFig. 2 Aging time dependence of the Vickers
hardness, conductivity and typical resonant frequency.

Attenuation coefficients, , were evaluatedfrom the analysis of the ring-down curves, and thedependence of attenuation coefficient against aging
time was also investigated. A clear trend was notobserved, but it seemed to show a slightly
increasing behavior, which would be due to theincrease of mobile dislocation density [12] and/or
the reduction of Cu solute atoms that enhances the
movement of each mobile dislocation. Further
studies are desirable to understand the details.
The present study shows that the solutedepletion during copper precipitation processes
would change the elastic constant of model alloys,
which suggests the potential of EMAR

measurement as a tool for NDE of irradiated RPVsteels especially on solute depletion.
4. Conclusion
Precipitation process of thermally aged
Fe–1wt.%Cu alloys were evaluated by the EMAR
method. The aging time dependence of resonancefrequencies showed an increasing behavior, which
is different from the peaking trend of the hardness.
This phenomenon relates to the increase of elastic
constant originated from the depletion of Cu soluteatoms in matrix, not from the formation of Cu
precipitates. This study suggests a possibility of theapplication of the EMAR method for NDE of thematrix state of irradiated RPV steels.
Acknowledgment
This work was supported in part by aGrant-in-Aid
for
Young
Scientists(A),
No.19686058, from the Ministry of Education,
Culture, Sports, Science and Technology of Japan.
The authors would like to thank Dr. H. Ogi foruseful discussions.
References
1. G. R. Odette and G. E. Lucas, Radiat. Eff.
Defects Solids, 144 (1998) 189.
2. K. Fukuya, K. Ohno, H. Nakata, S. Dumbill, andJ. M. Hyde, J. Nucl. Mater. 312, (2003) 163.
3. Y. Nagai, T. Toyama, Y. Nishiyama, M. Suzuki,
et al, Appl. Phys. Lett. 87 (2005) 261920.
4. T. Ishii, N. Ooka, T. Hoshiya, H. Kobayashi, J.
Saito, et al, J.Nucl.Mater. 307-311, (2002) 240.
5. A.L. Hiser and R.E. Jr Green, Mat. Res. Soc.
Symp. Proc., 503, (1998) 175.
6. M. Hirao and H. Ogi, EMATs for Science andIndustry, (Kluwar Academic Publishers, Boston,
2003)
7. T. Ohtani and K. Takei, J. Soc. Mat. Sci., Japan,
54, (2005) 607.
8. Y. Kamada, D. G. Park, S. Takahashi, et al, IEEE
Trans. Magn. 43 (2007) 2701.
9. A. Deschamps, M. Militzer, and W. J. Poole, ISIJInternational, 41 (2001) 196.
10. M. H. Mathon, A. Barbu, F. Dunstetter, F.
Maury, et al, J. Nucl. Mater. 245 (1997) 224.
11. J. Z. Liu, A. van de Walle, G. Ghosh and M.
Asta, Phys.Rev. B, 72, (2005) 144109.
12. H. Ogi, H. Ledbetter and S. Kim, Metall. Mater.
Trans. A, 32A (2001) 1671.

1P2a-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 51- 52
11-13 November, 2008

Non-Radiative Investigation of Photodecomposition ofPoly(di-hexyl silane) Thin Films by Using the Piezoelectric
Photo-Thermal Spectroscopy
非発光遷移検出によるポリジへキシルシランの光分解性評価
Atsuhiko Fukuyama1†, Takahiro Kuroki1, Kentaro Sakai2, Tomohisa Iwamoto3, Shoji
Furukawa3 and Tetsuo Ikari1 (1 Facult. Eng., Univ. of Miyazaki; 2 CRC, Univ. ofMiyazaki; 3 Graduate School of Computer Science and Sys. Eng., Kyushu Ins. Tech.)

福山敦彦 1，黒木貴裕 1, 境健太郎 2, 岩本朋久 3, 古川昌司 3, 碇哲雄 1（1 宮崎大 工; 2 宮崎大 産連
セ, 3 九工大 情報工学研究院）

1. Introduction

2. Experimental Procedures
PDHS thin films were prepared by using spin
coating method. After the 2 wt.% PDHS solution
was placed on the quartz glass substrate, substrate
was then rotated at 500, 1000, and 1500 rpm for 10s followed by additional rotation at 2000 rpm for 30s, respectively. The film thickness were measured tobe 211, 178, and 142 nm by using a contact typefilm thickness meter, respectively.
-----------------------------------------------------------a-fukuyama@cc.miyazaki-u.ac.jp

0.5

AbsorbancePolysilanes, as one dimensional semiconductors, have attracted much attention as new
materials for future optical and electonic devices
due to their unique properties resulting from thedelocalization of σ electrons along the silicon
backbone. For example, polysilanes exhibit anultraviolet (UV) absorption assigned to a σ-σ*electronic transition, its wavelength and intensity
are strongly related to the conformation of thesilicon backbone.1) Among them, Poly(di-n-hexyl
silane) (PDHS) has been investigated by many
researchers because it shows the phase transition
above room temperature with the thermochromism.
We have succesfully described the crystal structureof PDHS, silicon backbone has an all-transconformation, whereas the n-hexyl substituents
have an asymmetical conformation.2) However, aphotodecomposition caused by the UV-lightirradiation in air, has not been understood yet.
In this study, we have investigate thephotodecomposition mechanism from the electron
non-radiative recombination view point. We thenadopted the piezoelectric photo-thermal (PPT)
spectroscopy.3) By monitoring the non-radiativeelectron recombination, the PPT is a high-sensitive
method for investigating the optical property
especially for the very low absorption region. FromtheUV-light
irradiation
time
dependent
measurement in vacuum, the photodecomposition
mechanism are discussed.

0.6RT
211nm-PDHS

0.4
0.3
0.2

0s
100s
300s
500s
700s
900s
1400s
1900s
5900s

0.1
0
280 300 320 340 360 380 400 420 440

Wavelength (nm)Fig. 1
Effects of UV-light irradiation on the OA
spectrum of 211-nm-thickness sample
A 150-W Xe lamp attached with amonochromator was used as the probing light (20µW/cm2 at 380 nm) for the convensional opticalabsorption (OA) and PPT measurements. In the
PPT measurements, the probing light was focusedon the substrate side and the PZT detector was
directly attatched to PDHS film surface of thesample. Details of the PPT experimental procedureand setup have already been reported.3) All themeasurements were performed in vacuum at room
temperature. When the effects of UV-lightirradiation were measured, the intensity of the
probing light was set at 70 µW/cm2 at 380 nm tocause the photodecomposition of PDHS.
3. Results and Discussion
Figure 1 shows the effects of UV-lightirradiation on the OA spectrum of 211-nm-thicnkess
sample. Irradiation time was defined as the time
during the probing light of 350-380 nm were
irradiated on the sample. A strong absorption peakat about 370 nm and a broad absorption bandaround 320 nm that appeared in the 0-s spectrum
come from the σ-σ* electron transition in the
all-trans and helical conformations, respectively.1)

Acknowledgment
This work was supported in part by The Iwatani
Naoji Foundation’s Research Grant and by The
Saneyoshi Scholarship Foundation.

Normalized PPT Int. (a. u.)

25
0s
100s
300s
500s
700s
900s
1400s
5900s

RT
211nm-PDHS

20
15
10
5

0
280 300 320 340 360 380 400 420 440

Wavelength (nm)Fig. 2
Effect of UV-light irradiation on the PPT
spectrum of 211-nm-thickness sample

100

Transmittance (%)

With increasing the UV-light irradiation time,decreasing their intensities and blue-shifts wereobserved. These behaviors were caused by thedecrease of grain size of PDHS crystal, or decreaseof the effective length of the Si backbone chain.4)
Same behaviors were also observed in 178- and
142-nm-thickness samples.
Figure 2 shows the effects of UV-lightirradiation on the PPT spectrum of same sample. As
in the case for OA measurements, a strong peak at
about 370 nm was also observed, this is caused by
the electron non-radiative recombination of σ-σ*transition in the all-trans conformation. Most
important finding was that the PPT signal around
290 nm increased after irradiation. This peak is dueto σ-σ* electron transition in the helicalconformation. We have already reported an increaseof optical absorption around 267 nm inpoly(di-methyl silane) thin film after UV-lightirradiation.5) We also concluded that this caused byan increase of Si-O bonds due to the oxidization.
To investigate Si-O bonds, we measured the
FTIR spectra from 1500 to 4000 cm-1 before (0 s)and after (5900 s) the UV-light irradiation. Results
are shown in Fig. 3. Unfortunately, an absorption ofquartz glass substrate hindered the measurement of
Si-O bond absorption about 1050 cm-1. However,since all the measurements in the present study
were carried out in vacuum, the possibility of theoxidization of film may be very low.
As shown in Fig. 3, a fine structured
absorption around 2800 cm-1 was observed after
irradiation, this is due to C-H bonds.6) To increase
the C-H bonds, Si-C bond between backbone andside chain or C-C bond in the side chain groupshould be cut off. In this situation, Si-C bondhaving lower binding energy is a candidate for cut
by the UV-light irradiation. It seems reasonable tosuppose that the Si dangling bonds (DB) was
formed as a result of cut the Si-C bond by the
UV-light irradiation.7) In general, non-radiative
recombination provability via DB is high, this may
provide an increase of the PPT signal intensities
corresponding to σ-σ* transition in the helicalconformation.
To conclude, effects of the UV-lightirradiation in vacuum on the OA, PPT, and FTIR
spectra of PDHS were investigated. In addition to
cut of Si-Si main chain, a cut of Si-C bond wassuggested. This may yielded a formation of DB
resulting in the increase of PPT signal around 290
nm.

Quartz glass

RT

80
60
0s

40

5900s

20
0
1500

2000

2500

3000

3500

-1

4000

Wavenumber (cm )Fig. 3FTIR spectra before and after UV-lightirradiation
References
1. R. D. Miller and J. Michl: Chem. Rev. 89 (1989)
1359.
2. K. Takeuchi and S. Furukawa: J. Phys.: Condens.
Matter 5 (1993) L601.
3. T. Ikari and A. Fukuyama: Progress in
Photothermal and Photoacoustic Science andTechnology, Vol. IV, ed. A. Mandelis and P. Hess(SPIE, Washington, 2000) p. 145.
4. S. Furukawa and H. Ohta: Thin Solid Films
438-439 (2003) 48.
5. H. Ohta, T. Takamoto, T. Yasuda and S.
Furukawa: Thin Solid Films 449 (2006) 129.
6. N. Ostapenko, N. Kotova, V. Lukashenko, G.
Telbiz, V. Gerda, S. Suto and A. Watanabe: J.
Lumin. 112 (2005) 381.
7. F. Schauer, I. Kuřitka, P. Sáha, S. Nešpůrek, and
S. Lipson: J. Non-Cryst. Solids 352 (2006) 1679.

1P2a-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 53- 54
11-13 November, 2008

Frequency characteristics of the polyurea ultrasonicvariable-line-focus-beam-transducer
ポリ尿素可変線集束トランスデューサの周波数特性
Takahiro Aoyagi†, Marie Nakazawa and Kentaro Nakamura (Tokyo Inst. of Tech.)
青柳貴洋 ，中澤麻梨江，中村健太郎（東工大）

1. Introduction
Polyurea piezoelectric polymer films can beeasily fabricated by evaporative polymerization
through a complete dry process.1) The authors havestudied the applications of polyurea piezoelectricfilms such as ultrasonic transducers,2) a film-shaped
earphone3) and a three-axis-motion sensor.4) For theapplication of the ultrasonic transducer, the authors
have proposed the variable-line-focus-beamtransducer to measure surface acoustic wave
velocities,5) and theoretically analyzed the radiatedultrasonic beam6) as like in the V(z) curve method.7)
The calculated surface acoustic velocity has good
agreement with measured one8),9). However, thefrequency characteristics of the polyurea transducer
and V(W) curve were not described before. In thisreport, the detail of the polyurea film and thefrequency characteristics of the V(W) curve aredescribed.
2. Characteristics of the polyurea film ultrasonictransducer.
Figure 1 shows the geometry of the polyurea
film transducer. The top aluminum (Al) electrode(thickness, 3.3 µm), polyurea (PU) piezoelectricmaterial (thickness, 3.5 µm), and bottom aluminumelectrode (thickness 1.7 um), were deposited on apolyimide (PI) film (thickness, 25 µm). The active
region of the PU film where the electric field isapplied is confined to a rectangle of 2 mm×3 mm
area.

Fig. 1 Geometry of a polyurea ultrasonic transducer.

Fig. 2 Frequency characteristics for sound pressure of the water
loaded polyurea ultrasonic transducer.

Figure 2 shows frequency characteristics forsound pressure of the transducer when it is loadedwith the water. The sound pressure is analyzed byan equivalent circuit of a Langevin type vibrator10).
As shown in the figure, resonance frequencies are
obtained at about 30 MHz intervals. The resonancefrequency of the polyurea layer shown in the Fig. 1
is very high, such as GHz order. Essentially, theprinciple of the transducer is a Langevin typevibrator that has four layers. Thus, the transducer
has multiple thickness resonance characteristics. In
this report, V(W) curves of frequencies 30, 60, and
120 MHz are theoretically calculated.
3. Measurement system
Figure 3 shows the geometry for the surface
acoustic wave velocity measurements system.
Movable fixtures buckle the transducer to a curved
shape so that a focus beam is radiated from thetransducer. In this report, the transducer curvature isassumed to the sinusoidal shape described below.6)

Fig. 3 Geometry of the surface acoustic wave velocity
measurement.

y = "Rsin(

!

#
x)
W

(1)

Where x and y are coordinates of the transducer surface,
W is an interval of the movable fixtures, R is the curveheight that depends on W. A distance between thetransducer curve base and the specimen varies from 0.1
mm to 0.8 mm. The water fills between the transducer
and the specimen. The radiated beam reflects on thespecimen surface, while some parts of the radiated wave
excites the leaky surface acoustic wave on thespecimen-water boundary. By measuring the transducer
output for each width W, we can observe the ripple
caused by the interference between the reflected wave
and the radiation of leaky surface acoustic wave. The
surface acoustic wave velocity can be estimated by theripple period and amplitude change.

Fig. 5 V(W) curve for several LSAW velocities (h=0.1 mm,
Frequency=120MHz, vLSAW=2500, 3000, 4000 m/s).

3. Numerical calculations of the surface acoustic
velocity

4.

Figure 4 shows calculated responses forseveral frequencies using the calculation method
described in ref. 6. The height h is 0.5 mm. The
leaky surface acoustic wave velocity is assumed
3000 m/s. A solid line shows the case that there isno surface acoustic wave. Dotted lines show thecases of frequencies 30, 60, and 120 MHz.
Amplitude of each curves are normalized by thepeak value of without-LSAW case for eachfrequencies. The ripples caused by interference areobserved. Locations and amplitudes of the ripple
are varied depending on the frequency. The rippleof the V(W) curve decreases as the frequency
increases, and the number of the ripple increases as
the frequency increases.
Figure 5 shows a calculated V(W) curves for
120 MHz. The height h is 0.1 mm. The solid line
shows the without-LSAW case. Dotted lines show
the case LSAW velocity vLSAW is 2500, 3000, 4000m/s respectively. As shown in the figure, locationsof the peak of ripples vary with vLSAW.

Fig. 4 Frequency characteristics of V(W) curve (h=0.5 mm,
Frequency=30, 60, 120MHz, vLSAW =3000 m/s).

Conclusion

In this report, we presented the frequency
characteristics of the surface acoustic wave velocity
measurement using a polyurea piezoelectricvariable-line-focus-beam-transducer.
The interference ripple caused by the leaky surface
acoustic wave radiation varies as the input
frequency and the LSAW velocity. Optimaltransducer size and frequency for measurements
should be carried out for future study.
References
1. M. Iijima, S. Ukishima, K. Iida, Y. Takahashi
and E. Fukuda : Jpn. J. Appl. Phys. 34 (1995)
L65.
2. M. Nakazawa, M. Tabaru, K. Nakamura andS. Ueha : Jpn J. Appl. Phys. 46 (2007) 4466.
3. M. Nakazawa, K. Nakamura and S. Ueha : IEICE
Tech. Rep. EA2006-40 (2006) [in Japanese].
4. M. Tabaru, M. Nakazawa, K. Nakamura andS. Ueha : Jpn J. Appl. Phys. 47 (2008) 4044.
5. M. Nakazawa, T. Kosugi, A. Maezawa, K.
Nakamura and S. Ueha : Proc. Spring Meet.
Acoust. Soc. Jpn, 2006, p. 973 [in Japanese].
6. T. Aoyagi, M. Nakazawa, K. Nakamura andS. Ueha : Jpn. J. Appl. Phys. 46 (2007) 4486.
7. J. Kushibiki and N. Chubachi : IEEE Trans.

Sonics Ultrason. 32 (1985) 189.
8. T. Aoyagi, M. Nakazawa, M. Tabaru, K.
Nakamura and S. Ueha: Proc. Symp.
Ultrason. Electron, 28 (2007) 353.
9. T. Aoyagi, M. Nakazawa, M. Tabaru, K.
Nakamura and S. Ueha: Proc. IEICE generalconf. A-9-3 (2007) [in Japanese].
10. K.
Nakamura,etal.:Chouonpa(Ultrasonics) (Corona publishing, Tokyo,
2001) p. 54 [in Japanese].

1P2a-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 55- 56
11-13 November, 2008

Optical observation of Lamb Wave in Metal Plate Having a
Stepped Thickness
光学的方法を用いた段付き平板を伝搬する Lamb 波の測定
Ryota Kudo‡ and Kazuhiko Imano (Faculty of Engineering and Resource Science,
Akita University)
工藤良太‡，今野和彦(秋田大・工学資源)

1. Introduction

A1

Group velocity cg [km/s]

Phase velocity c [km/s]

S1 S2 A2

8
6 S0
4
A0

2
0
0

5 S0
4
3
A0

2

S2

1

A1

0
0

2
4
6
8
10
Frequency × Thickness fd [MHz mm](a) Phase velocity c

S1(b) Group velocity cg

A0

60

30 S0
A1

0
0

S1

S2 A2

2
4
6
8
10
Frequency × Thickness fd [MHz mm](c) Critical angle θc
Fig.1 Dispersion curves of Lamb wave inaluminum.
Personal Computer

Propagation characteristic of Lamb wave

The propagation modes of Lamb wave depend on
the thickness of materials and frequency of theultrasonic waves. The propagation characteristic of
Lamb waves can be theoretically calculated by theRayleigh-Lamb equation. The dispersion curves ofphase velocity c and group velocity cg in aluminum
plate (cL=6410 m/s, cT=3040 m/s) as shown in Figs.
1(a) and 1(b), respectively. Lamb wave can be
efficiently excited when the incident angle satisfies
the phase matching condition. This angle, which is
critical angle θc, is calculated from the Snell’s lawas,θ c = sin −1

cw
,
c

GP-IB
Trigger
Function Generator

Oscilloscope
0.2 mm interval scan

AmplifierReflect
MirrorLaser Doppler
Vibrometer

A0 Transducer
x = 0 mmx = 100 mm

x = 200 mm
x

Lamb wave
Aluminum
Plate

Fig.2 Experimental setup.
launch the A0-mode Lamb wave in the aluminum
plate.

(1)

where c is the phase velocity of Lamb wave, andcw(= 2500 m/s) is the velocity of the wedge. The
dispersion curves of the critical angle in aluminum
plate as shown in Fig.1(c). Thickness d andfrequency f used in this study are 1.0 mm and 2.0
MHz, respectively. In case of fd = 2.0 MHz mm,
the incidence angle θc was set to 72°(A0-mode), to-----------------------------------------------------------imanoken@ee.akita-u.ac.jp

A2

2
4
6
8
10
Frequency × Thickness fd [MHz mm]

90
Circle angle θc [deg]Propagation characteristic of Lamb wave isaffected by both the thickness of material andfrequency.1),2) The propagation behaviors in theplate having different thicknesses might be useful toobtain the defect information, however their
behaviors are very complex. Theoretical research of
the propagation of Lamb wave in plate having
variation thickness have been presented.3) On theother hand, there are few number of experimental
researches have been reported. The propagation
characteristic of Lamb wave having different
thicknesses is very important for the nondestructive
testing to understand the properties such as flaw,
hole, crack and abrasion.
In this paper, the propagation characteristic of
Lamb wave which propagating in aluminum plate
having a step variation of thickness is measured by
an optical observation method.
2.

6

10

3. Experimental Method and Results
Lamb wave measurement system is shown in
Fig.2. Transmission signal of 2.0 MHz, 1.0 Vp-p
and 10 cycles burst sin wave were applied to theA0-mode transducer. The laser vibrometer isscanned along the propagation direction of Lambwave from x = 0mm to x = 200.0 mm at intervals of
0.2 mm. In each point the surface vibrations of
Lamb waves are measured. The received vibrating

150 mm

150 mmd=1.0 mm-20

d=0.5 mmTransducer
Lamb wave

200 mm

100 mmAluminumPlate

1.0 mmdefectarea

Propagation time t [μs]

0
20
40
60
80
100

0.5 mm120

Fig.3 Aluminum plate used in this experiment.

0

100

200

distance x [mm]Fig.4 x-t distribution.

waveforms are digitized and fed to a personal
computer via a general purpose interface bus(GPIB).

4.

Conclusions

A0-mode Lamb wave converts to S0 mode inaluminum plate having a stepped thickness wasobserved. The mode conversion from A0-mode to
S0-mode would be occurred by the thickness change,
so that the mode properties of Lamb wave become
useful index to find the defect such as abrasion.

References
1.K.Horie et al.: Jpn. J. Appl. Phys. 44 (2005) 4333.
2.M.Watanabe et al.: Jpn. J. Appl. Phys. 45(2006)
4565.
3.P.Marical et al.: Ultrasonics 47, (2007)1.

2 A1
1

0

S0
A0

200 400 600 800 1000
Wave number k [m-1](a) d = 1.0 mm
4
3

A1

2

Normalized Amplitude [dB]

Frequency f [MHz]

S1

3

0
0

Frequency f [MHz]The k-f charts using two dimension Fouriertransform of x-t data are shown Figs.5(a) and 5(b),respectively. The peak of k-f distribution wascorresponded to the dispersion curve of theA0-mode in d = 1.0 mm. On the other hand, thepeaks were also corresponded to the dispersion
curves both A0-mode and S0-mode in d=0.5 mm.
The results were implied that A0-mode Lamb wave
converted to the S0-mode, in different thickness
area. The peak values of the spectrum of each modeare shown in Fig.6. The amplitude of A0-mode isdecreased by approximately 5 dB and that of
S0-mode is conversely increased by approximately
12 dB between 45 and 50 μs, so that mode
conversion would be occurred around the step of
the aluminum plate.

S2

-20
S0

1
0
0

A0

200 400 600 800 1000
Wave number k [m-1](b) d = 0.5 mm
Fig.5 k-f image lapped dispersion curves.
Normalized amplitude [dB]

The geometry of the aluminum plate used inthis study is illustrated in Fig.3, which has a step of
0.5 mm at the center of plate. Two dimensions
distribution of propagation distance x - time t of the
waveform received by the measurement system isshown Fig.4.

4

10
0
-10
-20
-30
20

○…A0-mode●…S0-mode
30
40
50
60
Propagation time [μs]Fig.6 Time - spectrum characteristic.

1P2a-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 57- 58
11-13 November, 2008

Evaluation of Acousto-optic Effect in Underwater UltrasonicPressure Measurement Using an Optical Interferometer
光干渉計を用いた水中超音波音圧計測における音響光学効果の評価
Youichi MATSUDA, Masahiro YOSHIOKA and Tsuneo KIKUCHI (NMIJ/AIST)
松田洋一，吉岡正裕，菊池恒男 （産総研）

1.

Introduction

A combination of a homodyne
interferometer and a pellicle normally arranged tothe ultrasonic propagation direction, featuring
non-contact and a small active element, has been
adopted for absolute pressure measurement [1,2]and visualization [3,4] of underwater ultrasound.
Because the interferometer probe beam transverses
and interacts with ultrasound, the interferometer
outputs include both pellicle displacement and thechange in the refractive index caused by theultrasound. The two effects have been evaluatedquantitatively using theoretical analyses [1,3,4], but
only for far-field ultrasound. Consequently,
evaluation of the two effects for near-field or
focused ultrasound is necessary. For this study, wedeveloped a system to discriminate the two effects.
Measurement results in a far-field ultrasound forsystem validation and in a small amplitude focusedultrasound are described herein.
2.

Comparing changes of the optical path length
observed using the two methods, the acousto-optic
effect was extracted.

Experimental

In this experiment, a tone burst ultrasoundfrom a transducer is detected using a combinationof a path-stabilized Michelson interferometer and apellicle stretched over a circular frame in water. A
1-μm-thick polyester film with a 300 nm gold
coating is used as the pellicle, which is acousticallytransparent and optically reflective. Generated
ultrasound is detected at almost identical positions
using two methods––a transmission method and areflection method––to discriminate ultrasonicdisplacement from the acousto-optic effect. Figure
1 depicts a sketch of the two methods. Because only
the pellicle is arranged in the transmission method,
ultrasound travels in water, passes through thepellicle, and interacts with the probe beam of theinterferometer. Both ultrasonic displacement andthe acousto-optic effect are observed there.
Meanwhile, because an air layer is introduced
behind the pellicle in the reflection method,
ultrasound travels in water, is almost perfectlyreflected at the pellicle–air interface; it does notinteract with the interferometer probe beam. Only
ultrasonic displacement is observed there.

Fig. 1 Two methods for underwater ultrasounddetection using a Michelson interferometer: (a)Transmission method and (b) Reflection method.

3.

Result for far-field ultrasound

For this study, the effective refractive
index of water using far-field ultrasound ismeasured and compared with the theoretical value
for the developed system validation. A planartransducer with a radius a of 6.3 mm generates
tone burst ultrasound. Ultrasonic frequency f is
1–10 MHz. The transducer-detection point distancez is approximately 37 cm i.e. the normalized
distance S = zλ a 2 is 1.5–15. Here, λ isultrasonic wavelength. Sound pressures at then* =2 × OPT ( f )× t R ( f ),OPR ( f ) × t T ( f )(1)

Effective refractive index n*

where OPT ( f ) and OPR ( f ) are changes of the
optical path length obtained using theinterferometer, and t R ( f ) and t T ( f ) are thedisplacement transmission coefficients through thepellicle. Subscripts T and R respectively represent
the values for the transmission method and thereflection method. The theoretical effective
refractive index n * for a light wavelength of 633
nm at 20°C is n* = 1.009±0.003 and is expected tovary by 0.01% for temperatures of 15°C to 25°C
[1,4]. Figure 2 portrays the experimental results.
The standard deviations of four independentmeasurements are about 1%. Measured values were
1.008–1.010, except for those at 7 MHz, 9 MHz,and 10 MHz. Furthermore, differences between
these three values and the theoretical value arewithin 1%. The measured values are roughly
equivalent to the theoretical ones.

1.02

1.15

1.1

1.05

1
0

5
Frequency (MHz)10

Fig. 3 Measured effective refractive index for small
amplitude focused ultrasound (Light wavelength =633 nm, Water temperature = 22.0°C).

1.01

5.

1
0

5
Frequency (MHz)10

Fig. 2 Measured effective refractive index for
far-field ultrasound (Light wavelength = 633 nm,
Water temperature = 22.0°C).
4.

pressures at the detection point are 5–200 kPa.
Ultrasonic frequency f and water temperature
are identical to those described in the previous
section. Results confirmed that the coefficients oft R ( f ) and t T ( f ) are regarded as the same as
those for the previous section. Figure 3 presents
experimental results of eight independentmeasurements. Measured values were 1.000–1.008;
their standard deviations are about 1% at
frequencies of 1–5 MHz. However, measured
values changed rapidly; their standard deviations
increased at frequencies of 6–10 MHz, probably
because of the increasing complexity of a focusedultrasonic field near the focal point at highfrequencies.

Effective refractive index n*detection point with no pellicle are 5–80 kPa forwater temperature of 22±0.5°C. The effective
refractive index n * is given as

Results for focused ultrasoundThe effective refractive index of water fora small amplitude focused ultrasound near the focal
point is measured. A 6.3 mm radius point focusingtransducer with a 10 cm focal length generates tone
burst ultrasound. The transducer-detection point
distance z is approximately 10 cm. Sound

Conclusion
A system to discriminate ultrasonicdisplacement from the acousto-optic effect wasdeveloped. The measured effective refractive index
of water for far-field ultrasound was roughly
equivalent to the theoretical value. The
acousto-optic effect in a small amplitude focusedultrasound was also evaluated using the system.
References
1. D. R. Bacon: NPL Report (AC 109) (1986).
2. T. J. Esward and S. P. Robinson: IEEE Trans.
Ultrason. Ferroelectr. Freq. Control 46(3),737-744 (1999).
3. R. S. Mezrich, K. F. Etzold, and D. H. R.
Vilkomerson: RCA Review 35, 483-519 (1974)
4. C. B. Scruby and L. E. Drain: Laser Ultrasonic:
Techniques and Applications. (Hilger, Bristol,1990), 148-164.

1P2a-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 59- 60
11-13 November, 2008

Abnormal Frequency Jump of Quartz Crystal Microbalance in Liquid
Sunhee Choi, Mikyung Lim*, Young.H. Kim (Korea Science Academy)

1. Introduction
Since Pierre and Marie Curie had discovered
piezoelectric effect, a quartz crystal has been widelyused for an accurate oscillator. Especially AT-cut
quartz crystal is mostly used because of the greatstability against temperature change. A quartz
crystal microbalance (QCM) is a device whichmeasures very small mass changes with thefrequency change of the quartz crystal in real-time.
The major application of QCM is thickness
monitoring in thin film deposition and a gas
detector.
Nowadays QCM is being developed as
biological sensors and therefore the behavior ofquartz crystal in a liquid has been studied. For
example, Kanazawa has proposed an equation
which described the frequency shift related todensity and viscosity of the liquid which quartz
crystal is immersed in [1]. König reported influenceof water droplet on the crystal and it seems contact
area have a relationship with the frequency shift [2].
In the present work, however, we observed thefrequency jump from near 6MHz to 9MHz whenquartz crystal is immersed in water. The frequency
will be changed in a small amount along the contact
area according to König’s research, but it justjumped regardless of the contact area. This work
tried to investigate this abnormal phenomenon andto explain the reason.

In order to clarify the frequency jump, time
domain waveform as well as frequency counting
were investigated. Frequency spectrum obtained by
FFT (Fast Fourier Transform) of time-domain
waveform was also investigated. For these purpose,the frequency counter (Agilent 53132A) and A/Dboard (NI PXI-5124) were employed in the present
work.
3. Result and discussion
Frequencies of quartz crystal were measured
1000 times for 10 minutes using frequency counter.
The average value and standard deviation of
frequency of quartz crystal are listed inTable 1. As shown in Table 1, quartz crystal in air
vibrates at about 6MHz, whereas frequency ofquartz crystal in water jumped to the 9.5MHz. It
was also found that oscillation in water is more
Table I the average and the standard deviation of thefrequency of quartz crystal in air and in water

average(Hz)in air

5.989507×10

in water

9.540×10

6

standard deviation(Hz)6

5.25
2.297×103

2. Experimental details
Fig.1 shows AT-cut quartz crystal of 6MHz
resonant frequency and 14mm diameter (Tangidyne,
TAN06IG). A dip holder is fabricated in order toisolate electrodes in liquid. Sycon VSO-100 was
employed for exciting quartz crystal, and its output
is ready for connection to the frequency counter.

Fig. 1 The electrode shape of TAN06IG [3]---------------------------------------------------------------------cjtwo120@hanmail.net* current address : KAIST, Dae-jeon, Korea

Fig. 2 The waveform of the signals from quartz crystal(a) in air, (b) in water

abnormal frequency jump. Since shear andlongitudinal wave speeds are 3.52×103m/s and5.57×103m/s, respectively, the ratio of jumped
frequency will be equal to the ratio of wave speeds,
5.57×103 / 3.52×103 = 1.58 [4]. The measured
frequency ratio, 1.59, shows good agreement withthe wave speed ratio.
4. Conclusion
In the present work, we investigated the
behavior of quartz crystal when it is immersed inliquid. The frequency was very unstable andjumped to near 9MHz in liquid. It was found thatwater makes frequency of quartz crystal jump tohigher frequency. Abnormal frequency jump seems
to be concerned with the longitudinal wave modeeven though the mechanism of mode change is not
explained.

Fig. 3 FFT of the waves from quartz crystal (a) in air(b) in water

unstable compared to that in air.
Time domain waveform was captured by A/Dboard. In order to observe the detail of waveform,
sampling rate was set to 1GS/s. In order to capture
waveform for frequency spectrum, sampling rate
was set 200MS/s with 107 data points so thatfrequency resolution was 20 Hz.
The waveforms of the signals from thequartz crystal in air and water are shown in Fig 2.
The waveform in air is similar to the square wave
with one high peak. The waveform in water issharper and takes shape of triangle. It is also foundthat the frequency is shifted from 6MHz to
9.5MHz.
Fig. 3 shows the frequency spectra. The
frequency spectrum shows a narrow resonant peaknear 6MHz in Fig. 3(a). On the contrary, those in
Fig. 3(b) shows broadly spread frequency
components near 9.5MHz.

Considering the measured results, there is
no doubt that water contact to quartz crystal
makes resonant frequency jump to higher
frequency. It implies that the water changes thevibration mode of crystal. Abnormal frequency
jump to higher frequency will be concernedwith a higher wave speed mode. AT cut quartz
crystal is normally oscillating in shear mode,and longitudinal wave speed is faster than shear
wave speed. Therefore longitudinal vibration
crystal is one of possible explanation ofReferences
1. K. K. Kanazawa, J. G. Gordon Ⅱ : Anal. Chem.
52, 1929 (1980)
2. A. M. K önig, M. Düwel, B. Du, M. Kunze, and
D. Johannsmann : Langmuir 22 (2006) 229-233
3. http://www.tangidyne.com/replacement.html
4. J. Krautkrämer, H. Krautkrämer : Ultrasonic
testing of Materials 4th Edition, (Springer-Verlag,
Berlin, 1990) p.561

1P2a-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 61- 62
11-13 November, 2008

Development of Micro-LFB Ultrasonic Device LFB$!

Jun-ichi Kushibiki, Yuji Ohashi, Mototaka Arakawa, Tomoya Tanaka, and
Sho Yoshida‡ (Grad. Sch. Eng., Tohoku Univ.)


, #

, , ‡,  %"

1. Introduction

2. Micro-LFB Device
Configuration of the micro-LFB device and its
measurement region on a specimen surface areillustrated in Fig. 1. A different point from thenormal-LFB device is that the micro-LFB device
has a cylindrically convex surface with a large
curvature radius RT for fabricating a ZnO-film
transducer. We made a micro-LFB device withthe following parameters: lens curvature radius-------------------------------------------------------------E-mail: kushi@ecei.tohoku.ac.jp

ZnO-FILM
TRANSDUCER

2b

RT

2a

l

L

θ

R

The line-focus-beam ultrasonic material
characterization (LFB-UMC) system1) is capable ofquantitatively evaluating various solid materials,
including single crystals, by measuring the phasevelocity of leaky surface acoustic waves (LSAWs)
propagating on a water-loaded specimen surface.
Perfect directionality of the LSAW propagation
direction that is realized by converging ultrasonicbeam into a wedge shape using a cylindricalultrasonic lens enables measuring the LSAW
velocity precisely. The spatial resolution of thissystem depends on a measurement region ofultrasonic beam widths along the focused direction,
W, and the along unfocused direction, D, formed by
the LFB device2). W is defined as W=2|z|tan LSAW
where z is the defocus distance in V(z) curvemeasurements and LSAW is the critical angle of
LSAW. As D for the normal LFB device isrelatively large, it is difficult to detect steep
variations of acoustic properties along theunfocused direction on specimen surface. Besides,
higher spatial resolution is required to evaluate
small crystals in a developmental stage. Although
directional point-focus-beam (PFB) device has beendeveloped in a viewpoint of the higher spatial
resolution,3,4) this is not sufficient for quantitativeevaluation because of imperfect directionality of the
LSAW propagation direction in principle. It isalso insufficient to simply reduce the transducer
width along the unfocused direction because ofdiffraction effect of the acoustic field.
In this paper, we develop a micro-LFB
ultrasonic device to improve the spatial resolution
along the unfocused direction.

&

z

x
y

y
z

x

SAPPHIRE
RODy

SPECIMENSURFACExz

CYLINDRICALCONCAVE
SURFACEDx

Wy
ULTRASONICBEAMREGIONz

LSAWPROPAGATIONDIRECTION

Fig. 1. Illustration of micro-LFB device andmeasurement region on specimen surface.
RL=1.0 mm, half-aperture angle =60°, transducer
curvature radius RT=13.0 mm, rod length l=12.0mm, and transducer widths of 2a=1.73 mm along
focused direction and 2b=1.50 mm along unfocused
direction.
3. Experiments and Discussion
We evaluate spatial resolution of the device at
225 MHz by measuring focused acoustic fields
using a PFB device as a detecting probe. Results
for the normal-LFB and micro-LFB devices areshown in Fig. 2. 3dB-down width of the acoustic
fields along unfocused direction was improved to0.26 mm for the micro-LFB device, as comparedwith that of 0.92 mm for the normal LFB device.
We also verified a capability of anisotropy
detection through measurements of angulardependence of LSAW velocities for anisotropicThe
crystal [(110)Ge standard specimen5)].
measured and calculated results are shown in Fig. 3.
Although measured velocities without calibration
do not coincide with those of calculated ones,
velocity variations reflect crystal symmetry as

RELATIVE INTENSITY [dB]0Normal-LFB

-5
-10
-15
-20
Micro-LFB

-25
-30
-2.0

-1.0
0.0
1.0
y POSITION [mm]2.0

Fig. 2. Acoustic field along y-axis direction(ultrasonic frequency: 225 MHz, transducer widthalong y-axis direction: 1.50 mm).

3100

4. Conclusion
We proposed a micro-LFB device with higher
spatial resolution and demonstrated its performance.
We succeeded in developing the device withmeasurement region of smaller than 1/3 incomparison with that for the normal-LFB device,
maintaining perfect directionality of the LFB device.
This device will be useful for characterizing small
precious samples.

5

LSAW VELOCITY [m/s]

predicted by theoretical calculations. We could
confirm the capability of anisotropy detection inthis micro-LFB device.
Furthermore, we demonstrated spatialdetectability through measurements of LSAW
velocity distributions for a Z-cut ZnO single crystal
specimen with large inhomogeneity. Results areshown in Fig. 4. Measurements were conducted
in 0.25-mm steps along x-axis and y-axis directions
with LSAW propagation direction parallel to thex-axis direction.
As the ZnO single crystal
specimen employed has large inhomogeneity inresistivity, we can observe LSAW velocity
distributions of more than 60 m/s in both results.
However, configuration of a region with low
LSAW velocities spreading around (x, y)=(-1.5 mm,
0 mm) obtained by the micro-LFB device is clear
triangle form while that by the normal-LFB device
is in blurred form. Besides, the lower velocity
area extended from (x, y)=(-1.0 mm, +2.5 mm) to
obliquely right downward in Fig. 4(b) could be
detected only by the micro-LFB device. These
results demonstrate that the micro-LFB device candetect finer velocity variations and inhomogeneities,
which could not be observed by the normal-LFB
device.

3000
2900

calculated

2800
2700

measured

2600-90 -60 -30 0 30 60
-100
[110]
[001]
DIRECTION [deg]90Fig. 3. Angular dependences of LSAW velocities
measured for (110)Ge standard specimen using
micro-LFB device.

Acknowledgement
The authors thank K. Asano for his great
effort with the experiments at the beginning of this
work.

3

3

2

2

y POSITION [mm]1) J. Kushibiki and N. Chubachi: IEEE Trans.
Sonics Ultrason. SU-32 (1985) 189.
2) J. Kushibiki, A. Ohkubo, and N. Chubachi:Electron. Lett. 17 (1981) 520.
3) J. A. Hildebrand and L. K. Lam: Appl. Phys. Lett.
42 (1983) 413.
4) J. Kushibiki, N. Chubachi, and E. Tejima:
Ultrason. Inter. 89 Conf. Proc. (1989) 736.
5) J. Kushibiki, M. Arakawa, and R. Okabe: IEEE
Trans. Ultrason., Ferroelectr., Freq. Control 49(2002) 827.

(b) Micro-LFB(a) Normal-LFB

y POSITION [mm]References

4

4

1
0
-1

1

2680

0

2660

-1

2640

-2

-2

-3

-3

-4

-4
-2

-1 0
1
2
x POSITION [mm]LSAW
velocity
[m/s]

2620
2600
-2

-1 0
1
2
x POSITION [mm]Fig. 4. LSAW velocity distributions measured for
Z-cut ZnO single crystal specimen.

1P2a-10

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 63- 64
11-13 November, 2008

Automatic Measurement of Nonlinearity Parameter B/A
for Small Volume Liquid Samples
少量液体試料の非線形パラメータ B/A の自動測定
Shigemi Saito1† and Jung-Ho Kim2 (1 School of Marine Science and Technology,
Tokai University 2 GW Corporation)
斎藤繁実 1†，金正鎬 2（1 東海大・海洋; 2 ジーダブリュー）

1. Introduction
The automatic measurement method for acoustic
nonlinearity parameter B/A in liquid sample has
previously been presented.[1] However the method
is only available to samples with attenuation
coefficients much lower than 200 Np/m at 19 MHz.
By setting a thin sample in the focal region of a
focused Gaussian beam, B/A in a more dissipative
sample has been successfully measured lately.[2,3]With the aim to generate the image of B/A
distribution, the automatization of the measurement
is examined in this work.
2. Measurement System
As shown in Fig.1, the LN transducer with aninverted polarization layer driven by 7-cycle burst
voltages of frequency f=18.6 MHz radiates a focused
Gaussian beam of 10.65 mm focal length in water(density ρW=1000 kg/m3, sound speed cW=1483 m/s)
through a solid acoustic lens. A space in a sample
container provided by a ring spacer inserted between
a PS plate and tungsten rod is filled with a liquidsample that forms a layer of thickness L≈1 mm. In
PS, the density ρd, longitudinal sound speed cd,
transverse sound speed ct and B/A are assumed to be1049 kg/m3, 2333 m/s, 1120 m/s and 11.4.[4] The 7
cycle burst waves take roundtrips across the sample.
The distance zR of the end of a brass rod from thelens surface is controlled with a stepping motor.

Brass rod
Sample container

Tungsten rod
SampleSpacerDistilled water
Polystyrene
plate
Lens

20°C water

LN transducer

Electronics

Fig.1. Experimental setup of acoustic system.

-----------------------------------------------------------ssaito@scc.u-tokai.ac.jp

To measure the magnitude of the reflected soundfrom any boundary, zR is adjusted so that theboundary locates on the focal plane. Since the soundreflected at the focal plane returns to the transducer
in phase, the signal obtained with the highest
sensitivity is accurately proportional to themagnitude of the reflected waves. All the acoustic
system is settled in an incubator at 20°C. In addition,
the sample and water couplant is held at 20°C withcirculation of cooling water.
3. Procedure of Automatic Measurement
The sound speed c and attenuation coefficient α
are determined by the time of flight and the
reduction rate of the sound passing through thesample, respectively. The density ρ is estimatedfrom the reflection coefficient at the interface
between the polystyrene plate and the sample.
Summarizing all the linear properties and amplitude
data of the second harmonic component in the soundtransmitted through the sample, the B/A value isfinally determined from the magnitude of second
harmonic generation. To compensate the influenceon the second harmonic generation, the velocity
dispersion is measured using a phase delay of 2f
sounds relative to f sounds in dual-frequency sounds.
To derive the acoustic properties, the parameterssuch as amplitudes, phases and time intervals areautomatically measured and executed using
LabVIEW programs constructed on the basis of theprevious method.[1]The range to maximize the amplitude of the wave
reflected from the rear surface of the PS plate,zR=D+(1-cd/cW)d, is registered as the reference
position of the z stage. The tungsten rod is immersed
alone in water, the waveform of the sound reflectedfrom its surface is recorded first as the reference
waveform used in cross-correlation computations.
Further, the amplitude PRB of the reflected wave
from the rear surface of the PS plate directly
attached to the tungsten rod is also obtained from the
maximum value of the cross-correlation function.
After setting the container filled with the sample,
the amplitude PSB of the reflected wave from the rearsurface of the PS plate is measured. The timeinterval τS to the subsequent wave reflected from theof the unknown parameter B/A in dependent of suchsensitivities. When B/A is adjusted so that thetheoretical PSN2/PWN2 equals to the experimental one,
B/A is determined to be the value.
4. Example of Measurement Results
The measurement result for the concentration
dependence of B/A in aqueous solutions of bovine
hemoglobin is shown in Fig.2. The trend of B/A
increasing with the concentration agrees with thevalue measured with thermodynamic method.[6]Further study is necessary for interpreting the reasonof discrepancy in B/A at high concentrations. The
manual operation of the measurement system would
require a time as long as 15 minutes for each point
except for the computation. This automatic
measurement including computations, however, wascompleted in 14 seconds.
5. Conclusions
By using an acoustic window of polystyrene plate,the automatic measurement for B/A of the sample
with a volume as small as 0.1 ml was carried out.
The imaging of the B/A distribution will be
investigated later as well as the speedup of thisautomated method.
Acknowledgment
This work was supported by a Grant-in-Aid for
Scientific Research (C) 19560429 from the Japan
Society for the Promotion of Science.
References
1. S. Saito, J.-H. Kim and K. Nakamura: Ultrasonics
44 (2006) e1429-e1433.
2. S. Saito, K. Saida and S. Takahashi: Jpn. J. Appl.
Phys. 47 (2008) 3859.
3. S. Saito, T. Watanabe and J.-H. Kim: IEICE Tech.
Rep. US2008-5 (April, 2008).
4. S. Saito and Y. Motohashi: Jpn. J. Appl. Phys. 47(2008) to be published.
5. S. Saito and T. Watanabe: IEICE Tech. Rep.
US2007-105 (January, 2008).
6. W. K. Law, L. A. Frizzell and F. Dunn: UltrasoundMed. Biol. 11 (1985) 307.
9
8
7
6
B /A

tungsten rod is simultaneously measured.
Furthermore, the following process is carried out.
(i) The tungsten rod is lowered by cL/cW. Then theamplitudes PS1 and PS2 are obtained with FFT for thesignal receiving the wave reflected from the tungsten
rod during the radiation of dual frequency wave
consisting of frequencies f and 2f. The phase delayΦS of 2f component relative to f component issimultaneously measured.
(ii) The second harmonic component PSN2 isobtained by the FFT of the reflected wave during thesound radiation of frequency f.
Prior to the sample measurement, the process of(i) and (ii) is applied to distilled water filling thecontainer, where c in (i) is cW. The corresponding
values PW1, PW2, ΦW and PWN2 are then obtained.
a) Determination of sound speed The sound speed
c is determined with the following equation.
2L
c=
(1)
τS
b) Determination of density Considering thetransformation from longitudinal to transverse waves,the reflection coefficient S=PSB/PRB at the rearsurface of the PS plate must satisfy
ρc − ρ d c d
S=R
,
(2)
ρc + ρ d c dwhere R is defined by ρ and c as follows[5]:R=A0-A1x-A2x2;c≤794 [m/s](3)=B0-B1y-B2y2-B3y3-B4y4-B5y5; c>794 [m/s]-22where x=log10c-3-4.377×10 q-2.4718×10 3q , y=log10c-3.7138×10-2q-1.425×10-3q2 and q=(1000-ρ)/100. The coefficients in Eq.(3) are A0=0.9087,
A1=0.114, A2=0.1181, B0=0.9047, B1=0.1842,
B2=0.5079、B3=1.2389, B4=6.884 and B5=21.126. By
substituting the measured values of S and c into
Eq.(2), the unknown ρ is determined.
c) Determination of attenuation coefficient The
diffeence of PS1 and PS2 from PW1 and PW2 isprimarily attributed to the difference of the sample
from distilled water in its attenuation. Considering
the impedance mismatching and focal shifting, theattenuation coefficients at f and 2f are derived ascP1
α n = n 2α W+ln(Q Wn ) ,(n=1,2),
(4)
cW 2L
PSn
where Q=ρc(ρdcd+ρWcW)2 /[ρWcW(ρdcd+ρc)2] and αW
is the attenuation coefficient in water at 18.6
MHz, namely, 8.65 Np/m.
d) Determination of B/A The amplitude PSN2
theoretically depends on B/A and velocity dispersionof the sample ΦW-ΦS as well as other linear
properties such as ρ, c, α1 and α2.[3] Although boththe amplitudes PSN2 and PWN2 are dependent on thetransmitting and receiving sensitivities of thetransducer, the ratio PSN2/PWN2 becomes the function

5

Prsent method

4

Literature value at 25 C

3
2
1
0
0

5

10

15

20

25

30

35

40

% Concentration

Fig.2. Measured B/A of aqueous hemoglobin solution.

1P2a-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 65- 66
11-13 November, 2008

Sensing Grid for Air Temperature Composed of
Asynchronous-Type Sound Probe
非同期型音響波プローブで構成するセンシンググリッドによる気温計測
Yosuke Katano‡, Naoto Wakatsuki and Koichi Mizutani (Univ. Tsukuba)
片野洋介‡,若槻尚斗,水谷孝一 (筑波大院 シス情工)

1. Introduction
In recent years, a thermal environmental
measurement is required in various fields to maintain an optimum environment for life space,large-scale farm, and so on.1,2) And, the heat island
phenomenon and global warming progress. Therefore, the temperature management in the building
group in the big city or the large-scale facilities are
regarded as very important.
In conventional temperature measurement
method in large-scale space, contact-type sensors
like thermocouples and thermistor have been used.
Although the temperature distribution measurement
using these sensors is easy, a lot of sensors are required for large-scale measurement.3) In addition,
the disturbances such as direct sunshine and radiantheats influence the measurement. Because contact-type sensors are required to be installed in themeasurement area, they consume some space there.
On the other hand, temperature measurement using
sound probe is non-contact and non-destructive
measurement, and a measurement method is tolerant of such a disturbance. Sound probes have an
advantage of measurement ability by a little number of sensors and less space consumption.4)
The network of the measurement system
for temperature distribution in a large-scale space
has been suggested by the authors.5) In the network,a trigger line was wired by cable for accurate synchronization while data communication was done
by wireless. It becomes easy to construct a sensing
grid if trigger cables are omitted. This gives flexibility to the sensor arrangement. Therefore, wesuggest a temperature measurement by acousticalmeans without trigger signal as the former stage ofthe large-scale space measurement. The validity ofthe measurement principle is confirmed by experiment.
2. Principle
The temperature measurement principle
using sound probe is transferred to reference.5) In
the conventional temperature measurement using
sound probe, the operation beginnings of two
acoustic sensors are completely synchronized tomeasure time of flight (TOF), tf . Synchronous accuracy influences the measurement accuracy at the
TOF. Because wireless LAN causes the variation of
the delay of a few milliseconds, it cannot be used

(a)

τ1

t1

t21
t12
(b)

∆t

t2

τ2
Time
Fig.1 Measurement principle Outline(a) :Reception waveform of MIC1(b) :Reception waveform of MIC2

to transmit and receive the trigger signal. In former
research of authors, synchronization was taken by
the trigger line using a coaxial cable. To achievecompletely wireless sensing grid in this research,the measurement method without trigger signal wasinvestigated. The delays caused in wireless LAN
are compensated by using the round-trip TOF.
Figure 1 shows the timings of signal receptions. The times between the transmissions ofcommand to start the measurement and actual beginnings of measurement on MIC1 and MIC2 aredefined as t1 and t2, respectively. The difference
between t1 and t2 is defined as ∆t. TOFs from the
speaker 1, 2 to the microphone 2, 1 are respectively
defined as t12 and t21. Signal arrival times from two
speakers are defined as τ1 andτ2. These relations aredescribed asτ1 = t12 + ∆tτ 2 = t21 − ∆tt total = τ1 + τ 2= t12 + t 21
ttotal ≈

2Lc
2L
≈
2
c
c −Vd
2

(1)

(2)

(3)

Adding τ1 to τ2 can eliminate the influence of thedelay be eliminated, and gives the round-trip TOF
ttotal. Thus, the sound speed is obtained from eq. (3),and air temperature is derived.
The component of the wind velocity parallel to the propagation path is defined as Vd. Whenthe velocity of the wind is substantially smaller
than sound speed, the influence can be disregarded.

Sensor 1

Sensor 2

Pa

th

4

Pa

Path 5

Path 2

7.16m

4.55m

Path 1th

3

Path 6
Sensor 3

4.54m

Sensor 4

roof hight = 3.08m

Thermocouple
SensorN

Fig.2 Experimental composition.

29
Path 128
27

Sound Probe
Thermocouple

29
28
27

Path 2Temperature( )3. Experimental validation
3.1 Experiment Setup
Figure 2 illustrates a composition of theexperiment. Air temperature are measured in theroom (7.16 × 7.44 × 3.08 (m)). Four acoustic sensors are set at the corner of the 4.55 × 4.54 m2
square and form the network by wireless LAN(IEEE802.11b). Each sensor, which consists of a
microphone and loudspeaker and amplifiers, isconnected to the PC via A-D/D-A converter. The
experiment was carried out at 10s intervals fromlocal time of 0:00 to 5:30. The temperature at thecenter of the room has been changed by heating
wire from 2:30 to 3:30. The Reference used thermocouple. The thermocouple was set up in nine
points as shown in Figure 2. For separating fromthe signal received on each acoustic sensor, fourkinds of signals were used. First and second signal
was a ten-wavelength burst sound modulated from
7 to 3 kHz and from 3 to 7 kHz in linear frequency
at sensor 1, 2. Third and Fourth signal was used a
22-wavelength curst sound modulated from 7 to 17
kHz and from 17 to 7 kHz in linear frequency at
sensor 3, 4. Because the sampling rate of the
A-D/D-A was 250 kHz, the time resolution was 4
µs.

7.44m

29 Path 3
28
27

29
28
27

Path 4

29
Path 5
28
27
Path 6

3.2 Results of temperature measurement
Figure 3 shows measured temperatures
along acoustic paths. The solid lines and brokenlines represent the temperatures measured by soundprobes and thermocouples, respectively. Similar
behaviors are observed by both asynchronous-typesound probe and thermocouple. Because of thevariation of ∆t, the measurement fails to detect apeak in cross-correlation once in a while.

4. Conclusions
In order to measure the air temperature of
the large space, we examined the measurement
method using the asynchronous-type sound probe.
We experimentally verified the adequacy of thismeasurement method in a room as the primarystage. The wiring is omitted using the asynchronous-type sound probe and the flexibility of thecomposition of the sensing grid increases. The conclusive peak detection technique would be requiredin order to eliminate measurement failures.
.

0:00

1:00

2:00

3:00

4:00

Time (1 hour/div)
Fig.3 Temperature transitions along six acoustic paths.

References1). J. E. Son, J. S. Park and H. Lee: Acta Hort. 578(2002) 257.
2). D. J. Tanner and N. D. Amos: Acta Hort. 599(2002) 193.
3). I. Saito, N. Wakatsuki, K. Mizutani, M. Ishii, L.
Okushima and S. Sase: Jpn. J. Appl. Phys. 47(2008) 4329.
4). K. Mizutani, K. Itoga, K. Kudo, L. Okushima,
and N. Wakatsuki: Jpn. J. Appl. Phys. 43 ,(2004) 3090.
5). K. Sawamura, K.Mizutani, Kashiwazaki, and I.
Odanaka: The 26th Symposium on UltrasonicElectronics, P2-13, (2005) 237.

29
28
27
5:00

1P2a-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 67- 68
11-13 November, 2008

Ultrasonic Measurements of Temperature Distributions of the
Inside and Surface of Materials
超音波による材料内部および表面の温度分布計測
Manabu Takahashi1‡ and Ikuo Ihara2 (1Graduate Student of Nagaoka Univ. of Tech.;2
Dept. of Mech. Eng., Nagaoka Univ. of Tech.)高橋学 1‡，井原郁夫 2 （1 長岡技科大院; 2 長岡技科大）1. Introduction

In various fields of science andengineering, there are growing demands fornoninvasive measurements of the temperature
distribution and its transient variation of amaterial being heated. In our previous work1), an
ultrasonic inverse method to determine thetemperature distribution inside material was

proposed and its validity was demonstrated.
In this work, an improved ultrasonicmethod that can be used for practical andversatile applications has been developed. The

method consists of an ultrasonic pulse-echomeasurement and an inverse analysis coupled witha one-dimensional finite difference calculation. To

evaluated. Using a concept of trapezoidal
integration, the transit time tL given in equation (1)can be calculated from
N −1
 1
1 
1
t L = h n + n  + 2h ∑ n ,i =2 vi
 v1 v N (3)where h is the grid interval, N is the number of thegrid, vin is the ultrasonic velocity at each grid
position, i and n are indices corresponding to spatial
coordinate and consecutive time, respectively.
Considering that the single side of the medium
having a uniform temperature Tn at time step n isbeing heated, temperatures at each grid point in themedium at time step n+1 that is a very short elapsed
time can be given by2)(

) (i = 2,", N −1) (4)demonstrate the practical feasibility of themethod, temperature distributions of internaland surface of a material are evaluated.

Ti n+1 = Ti n + r Ti+n1 + Ti−n1 − 2Ti n

2. Ultrasonic Inversion Method for Determining
Temperature Distributions

where α is the thermal diffusivity, τ is the time
step. Using equation (3) and the relation between
temperature and ultrasonic velocity, the temperatureof the heated surface at time step n+1, T1n+1, can begiven by

The principle of temperature measurement by
ultrasound is based on temperature dependence ofthe velocity of the ultrasonic wave that propagates
through a medium. Assuming a one-dimensionaltemperature distribution in a medium, the transit
time of ultrasonic pulse-echo in the direction of thetemperature distribution can be given by1dx ,0 v(T )

tL = 2∫L(1)where L is half the transit distance of ultrasound,v(T) is the ultrasonic velocity that is a function oftemperature T. In general, the T in a medium being
heated can be given as a function of location x andtime t. It is also noted that the temperaturedependence of the velocity v(T) may have anapproximate linear relation in a certain temperature
range and can be given by
v(T)= -aT+b,(2)
where, a and b are constants.
We now consider a one-dimensional finite
difference model consisting of a large number ofsmall elements and grids, for the medium to be-----------------------------------------------------------E-mail address: ihara@mech.nagaokaut.ac.jp

r=

ατ
h2

T1n +1 = −(5)

1t  11 a  L −  n +1 + 2∑ n +1 i = 2 vi h  vN
N −1

+

b
,
a

(6)

where tL is the transit time of ultrasonic wave
measured at the time step n+1. It is noted that thetemperature of the other side of the medium, TNn+1,
is assumed to be known because such temperature
at a low temperature side can be easily obtainedusing any conventional technique such as athermocouple. Once the temperatures of all grid
points in the medium at the time step n+1, T1n+1,…,
TNn+1 are obtained, the temperature distribution attime step n+2 can also be determined by the sameprocedure using the transit time tL measured at thetime step n+2. Thus, we can continuously obtain thetemperature distribution.
3. Experiments and Results
At first, the proposed method has been applied
to an internal temperature measurement of a thicksteel plate being heated and cooled. A surface of asteel plate of 30 mm thickness is heated bycontacting with a heater of 200 oC for 100 s, andthen the surface is cooled by water. Ultrasonicpulse-echo measurements at 2 MHz are made forthe plate and the transit time tL through the plate ismeasured during the heating and cooling. Theinternal temperature and its variation estimatedfrom the tL is shown in Fig. 1. It can be seen that theultrasonically estimated results almost agree withthose measured using thermocouples.
Next, we attempt surface temperature
measurements by a surface acoustic wave (SAW).
Figure 2 shows a schematic of the experimental
setup used for SAW measurements. Using a laser
ultrasound system consisting of a pulse laser
generator (Nd:YAG, 1064 nm, 20 mJ, 10 ns) and alaser interferometer based on photorefractive
two-wave mixing (Nd:YAG, 532 nm, 200 mW), theSAW propagating on the surface of a steel plate
being heated is measured. Taking the difference inthe transit time between SAW1 and SAW2, thetransit time tL of the SAW propagating through the
distance between A and B can be determined. An
infrared camera is used to obtain a reference valueof surface temperature distribution of the plate.
Figure 3 shows the variations of thetemperatures at A and B and the tL of SAW on thesteel surface during heating. As we expected, thetemperatures start to rise just after the heating starts
and we can see that the transit time increases
drastically with the rise in temperature of the plate.
Figure 5 shows the variations of the estimatedsurface temperature distributions with the elapsed
time, where the ultrasonically estimated results arecompared with those measured using an infrared
camera. It can be seen that both temperature
distributions almost agree.

Scientific Research (B19360330) from the JSPS,
and Toyota Motor Co. are greatly appreciated.

Acknowledgment
Financial supports by the Grant-In-Aid forFig. 3 Variations of the temperatures and the transit
time of the SAW on the steel surface during heating.

120 s
50 s

60

200 s

20 s
40

300 s

SAW2

0

PBS

B

Infraredthermography

Pulse laser
Generator
λ/4 BE

90mm
SAW1
A
Heater350 oC

Mirror
Cylindrical lens

160
140
120
100
80
60
40
20
0

29.9

Temperature at A

29.8

Transit time
Raw data
Averaged

29.7

Temperature at B

0

100

200

300

29.6

Transit time (µs)

Temperature (oC)Fig. 2 Schematic of the laser ultrasonic system used
for measuring SAWs on a steel plate being heated.

400

Measurement time (s)IR-camera
Ultrasound

100
360 s
120 s
30 s

50

10 s
0s

0s

20

Laser
Interferometer

C
20mm

150

Thermocouple
IR camera
Ultrasound

100 s

80

Steel
Plate

Temperature (oC)

Temperature (oC)100

References
1. M. Takahashi and I. Ihara. Jpn J. Appl. Phys. 47(2008) 3894.
2. W. Press, S. Teukolsky, W. Vetterling and B.
Flannery: NUMERICAL RECIPES in C++(Cambridge Univ., NY, 2003) p.849.

5

10

15

20

25

30

Distance from heated surface (mm)Fig. 1 Internal temperature distribution of the steel
plate and its variation during heating and cooling.

0

20

40

60

80

Distance from A (mm)Fig. 4 Surface temperature distribution of the steel
plate and its variation during heating.

1P2a-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 69- 70
11-13 November, 2008

Measurement of Air Humidity Using Ultrasonic Delay Line
音響遅延線による湿度計測
Akihiko Kon†(Univ. of Tsukuba/Yamatake),
Naoto Wakatsuki and Koichi Mizutani (Univ. of Tsukuba)
昆昭彦†（筑波大院･シス情工/山武）、若槻尚斗、水谷孝一 （筑波大院･シス情工）

1. Introduction
To measure many physical factors like distance[1], sound velocity[2], temperature[3,4] and humidity[5] using ultrasound are widely used becauseof the features of the ultrasound such as non-contact
and non-disturbing for the measured environment.
Measurement method of the air temperature using atime of flight (TOF) or an ultrasound velocity
measured has been accepted. When the condition of
the air humidity becomes nearly saturated and temperature has higher values than the temperature
without humidity namely “dry temperature (Td)”,
the value of TOF becomes smaller and the soundtravels faster. This decreased TOF induces errors
for measurement of distance, temperature and humidity. There are several works[6,7] on the relation
between humidity and properties of the sound in aclosed space but the measurement of humidity were
not described. New non-contact measurement
method of relative humidity is described and experimentally verified at several humidity andtemperatures.
2. Principle Measurement
When an ultrasound with frequency f (kHz) istransmitted from a speaker (SP) to a microphone(MIC), which makes the ultrasonic delay line withlength L (m), the measured TOF introduces soundvelocity c (m/s) as c = L / TOF. The sound velocity
has relation with air temperature T (°C) as c =331.5 × [(273.17+T) / 273.15]1/2 = 20.067 × (273.17+T)1/2. This temperature must be virtual temperature.
A new equation of relative humidity U (%) is introduced as following: Parameters γ (=1.4 air), P(Pa), Pv (Pa) and Pd (Pa) are ratio of specific heats,
atmospheric pressure, vapor pressure and dry airpressure, respectively. Parameters ρ (kg/m3), ρv(kg/m3) and ρd = 1.29 × 273.15 / (273.15 +Td) × P /101325 (kg/m3) are air density, density of vapor anddensity of dry air, respectively. And parameters M(kg/mol), Md (=0.028966) (kg/mol), MV (=0.018)(kg/mol) and R (=8.324472) (J/mol·K) are mass ofair, molecular mass of vapor, molecular mass of dry
air and gas constant, respectively. Pv and Pd arepresented as Pv = γ × R × (273.15 + Td) / Mv and Pd= γ × R × (273.15+Td) / Md. With saturated vapor-------------------------------------------------------------kon-akihiko@jp.yamatake.com

pressure Pm (Pa), the relative humidity U is defined
as U=100×Pv/Pm. Using sound velocity c = (γ × P /ρ)1/2, the ratio Pv / Pm is presented as
PV
P × M d × ρV
= dPm Pm × M V × ρ d⎞⎛c2 × M d⎜−1 ⎟P ⎜ γ × R × ( 273.15 + Td ) ⎟ .
= d ×⎜⎟Pm ⎜c2 × MV⎟1−⎜ γ × R × (273.15 + T ) ⎟
d ⎠
⎝

(1)

When the empirical Antoine equation is adopted
to the saturated vapor pressure and an assumption
P=Pd is considered because Pv is smaller than Pd,
the relative humidity is obtained as
100 × P⎛
4030.183 ⎞⎟133.322 × exp⎜⎜18.6686 −
253 + Td ⎟⎠⎝⎛⎞c 2 × 1.293 × 273.15⎜−1 ⎟
γ × (273.15 + Td ) × 101325
⎜
⎟.
×⎜
⎟
2
MV
×
1
.
293
×
273
.
15
c
⎜1−
⎟
×
⎜
M d γ × (273.15 + Td ) × 101325 ⎟⎠
⎝

U=

(2)

Our experiments are validated using eq. (2), whichshows the principle for the non-contact measurement of the relative humidity using sound velocity.
3. Experimental setup and Results
Figure 1 shows experimental layout of SP and
MIC and equipments for measurement. The SP and
MIC (PT40-18N, PR40-18N/Nippon Ceramic) operate for sinusoidal ultrasound at 40 kHz. The pairof SP and MIC was fixed on a rail for optical use.
The SP and MIC constitute an ultrasonic delay line
whose length L was set to 89.45 mm. A function
generator (AGF310/Sony Tektronix) and a digital
oscilloscope (2230/Tektronix) were used for generating probing signal and for comparing phase difference Δφ (rad) between transmitted and received
ultrasound. Calibrated a humidity sensor/ thermometer (MS-6503/Mastech) and a pressure sensor(TSD01V/VITEC) were used for the references.

Fig. 2 Relative humidity measured in the chamber
at various temperatures.
Experiment data are obtained using eq. (2) at reference temperatures.

Fig. 1 Schematic of experiment.
Δφ is measured and converted into ΔTOF. Reference humidity and reference temperature in thechamber are also measured. Humidity is set at 30,
50, 75 and 100 % RH and temperature is set at 10,
20, 35 and 50 °C.
In order to change the environments at temperatureand humidity a temperature & humidity chamber(PR-3KF/ESPEC) was used. The temperature was
set to 10, 20, 35 and 50 °C. The relative humidity
was set to 30, 50, 75 and 100 %RH. The pair of SP
and MIC and the probe of the humidity sensor/thermometer were put in the chamber. The humidity affects the TOF of ultrasound. The base of
TOF is that measured at 0 °C. The change of soundvelocity Δc (m/s) from 331.5 m/s is determinedfrom the difference of TOF (ΔTOF) from the base
TOF as⎛⎞1
20.067Δc = 20.067 × ⎜⎜−× ΔTOF ⎟⎟L⎝ 273.15
⎠

−1

(3)

Figure 2 shows measured relative humidity.
The experimental data were 54.2, 59.7, 63.7 and40.0 %RH, whereas reference data were 48.9, 48.2,
51.7 and 53.2 % RH for set value of 50 % RH for
example. Nevertheless the differences between thereference and experimental data at 50 °C appear
clearly and the errors between the reference and theexperiment data are 17.8 % or less, the experimental data have same tendency with the reference data
and are close to the reference data. These results
suggest the experiments were valid and thenon-contact measurement of the relative humidity
using eq. (2) is useful and acceptable.
4. Conclusion
Conventional method of humidity measurement
using ultrasound velocity measured has some errors
because of the increased sound velocity caused by
the air humidity. A new equation is introduced for
non-contact measurement of relative humidity usingreference temperature, atmospheric pressure andsound velocity measured. Experiments based on themethod using the equation (2) were carried out. The
experimental data of relative humidity approximately agree with the reference data so that it suggests that this non-contact measurement of the relative humidity using the sound velocity affected by
the humidity could be adaptable for practical use.
We will perform experiments for data to establish
more accurate measurement method of relative humidity.
References
1. F. E. Gueuing et al.: IEEE Trans. Instrum. Meas.
46 (1997) 1236.
2. K. Ikeda: Jpn. J. Appl. Phys. 37(1998) 3047.
3. K. Mizutani, S. Kawabe, I. Saito and H. Masuyama: Jpn. J. Appl. Phys. 45 (2006) 4516.
4. K. Mizutani, K. Itoga, K. Kudo, L. Okushima
and N. Wakatsuki: Jpn. J. Appl. Phys. 43 (2004)
3090.
5. E.J.Evans and E.N.Bazley: Acoustica 6(1956)
238
6 R. Raspt, C.J. Hickey and J. M. Sabatier:J.Acoust.Soc.Am. 105 (1999) 65.
7. Y. Mao: J.Acoust.Soc.Am. 104 (1998) 664.

1P2a-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 71- 72
11-13 November, 2008""# $ #"# $ !
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1P2a-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 73- 74
11-13 November, 2008

Measurement of Vertical Temperature Distribution
Using Sound Probe with Reflectors
反射を用いる音響波プローブによる垂直温度分布計測
Ikumi Saito‡, Koichi Mizutani, Naoto Wakatsuki and Satoshi Kawabe (Univ. Tsukuba)
齋藤育‡，水谷孝一，若槻尚斗，川辺聡 （筑波大院・シス情工）

1.

Reflector nIntroduction

Area ncn
Tn

Efficient airconditioning systems are neededfrom various perspectives such as realization of
comfortable working conditions and energy
saving1,2). To maintain adequate indoor temperatureis the most important. In recent years, facilities tend
to grow in size for the mechanization andautomation. Therefore, it is difficult to keep
adequate indoor temperature in whole spaces. It isnecessary to measure temperature distribution forrealization of the efficient airconditioning
systems3,4). In particular, the vertical temperature
distribution is more apparent more than thehorizontal one. However, the vertical temperature
distribution is difficult to measure in large scale
spaces. In this paper, we discribe a measurement
system of a vertical temperature distribution using
sound probes with reflectors. By using thereflectors, the temperature distribution can bemeasured by a single pair of a loudspeaker (SP) anda microphone (MIC).
2.

Figure 1 shows a schematic of themeasurement of the vertical temperature
distribution using sound probes with reflectors. Thismeasurement system consists of a single pair of aSP, MIC and n reflectors. Therefore, this system hasn sound probes. Here, areas bounded by reflectors
are defined as Area 1, Area 2, … and Area n. The
propagation paths between the acoustic sensor andeach reflector are defined as L1, L 2, … and L n (m)and times of flights (TOFs) of each sound probe aredefined as t1, t2, … and t n (s). In addition, the meansound velocity of each area is defined as c1, c 2, …
and c n (m/s) and the mean temperature of that isdefined as T1, T2, … and Tn (°C). The temperature
distribution can be measured from the temperaturesof these areas. The sound velocity in Area 1, c1 isexpressed as

2 L1
.
t1

(1)

-------------------------------------------------------------E-mail:saitou@aclab.esys.tsukuba.ac.jp

Area n-1
cn-1
Tn-1

Ln

ln
Reflector3

Ln-1

Area 3c3
T3

ln-1

Reflector2
l3

L3

Area 2c2
T2

L2

Area 1c1
T1

Reflector1
l2
l1

L1

SP and MIC
Acoustic Reflector
Sound path

Fig. 1 Schematic of a measurement of temperature distribution
using sound probes with reflectors.

Principle of measurementc1 =Reflector n-1

The sound velocity depends on the mean
temperature on the propagation path. Therefore, themean temperature T (°C) is expressed asT=T0c 2 − T0 (T0 = 273.15 K).
331.32 2(2)

The mean temperature in Area 1, T1 can be obtained
from eq. (2) by substituting the sound velocity, c1.
In addition, the TOF in Area 2, t2 is expressed as
t2 =2l1 L2 2(l 2 − l1 )L2+,
l1c1
l 2 c2(3)where l1, l2, … and ln denote the heights ofreflectors from the acoustic sensor. c2 is given bysolving eq. (3),c2 =2(l 2 − l1 )L2 c1,
l 2 t 2 c1 − 2l1 L2(4)

c1 has already been obtained by eq. (1). Thus, themean temperature in Area 2, T2 can be calculated.
Here, the general form of eq. (3) is expressed as

2l n−1 Ln 2(l n − l n−1 )Ln+,l n cnl n cn' −1

where c’n-1 is the apparent velocity of the soundreflected by Reflector n-1, c’n-1 is expressed as

c

'
n −1

32.0

(5)

2L
= n −1 .
t n −1(6)

30.0

Temperature ( C )tn =Experimental verification and result

Figure 2 shows a schematic of theexperimental setup. The experiment was carried out
in an anechoic room. A SP and MIC was located on
the floor and three acoustic reflectors were locatedat the heights 1.00, 1.45 and 1.95 (m) from theacoustic sensor, respectively. That is, thismeasurement system has three sound probes. The
reflectors are made of plastic disks of 0.2 m (H) ×
0.3 m (V). The transmitted and received signals
were processed using a personal computer. The
received signals are sampled by the A-D and D-A
converter (National Instruments) with the sampling
frequency at 250 kHz. The transmitted signals werechirp signals of 5.0 ± 2.5 kHz with ten waves. The
TOFs were determined from the cross correlation of
the transmitted and received signals. The measured
Acoustic reflector3

0.2 m

0.3 m
Ref. 1

0.5 m
Acoustic reflector
Acoustic reflector2

SP and MIC
Thermocouple
Sound path

Ref. 3

0.25
0.1

2.21
Ref. 40.45 m

1.76

1.38
1.0 m

Ref. 7

0.25
0.125

0

15

30

45

Table I Mean temperature results for 45 minutes in each area.
Measured ( C)
References ( C)
Error ( C)

Area1

Area2

Area3

26.4
25.5
1.1

27.1
26.0
1.1

27.7
26.8
0.9

TOFs were obtained by averaging from fivemeasurements. The temperature was measured
every 20 seconds for 45 minutes. Reference valuesof the temperature were measured using eight
thermocouples.
Figure 3 shows the experimental result ofmean temperature in each area. Table I shows themean temperature results for 45 minutes in eacharea. The mean temperature in each area contains
error within 1.1 °C. From these results, it wasverified that this measurement system using thereflectors is superior to the response against thetemperature change and it can measure the verticaltemperature distribution.
4.

Conclusion

In this paper, we described a measurement ofa vertical temperature distribution using soundprobes with reflectors. The mean temperature ineach area could be measured with errors within
1.1 °C. In addition, we verified the response ofsound probes against the temperature change andcould simplify the system to measure thetemperature distribution. It is considered that theconstitution of this system can more simplify byusing the wall and ceiling of spaces.

Acoustic reflector1

Ref. 5

Ref. 6

Average of Ref. 1 and 2
Average of Ref. 3 and 4
Average of Ref. 5 - 8

Area3
Area2
Area1

Fig. 3 Experimental result of mean temperature in each area.

(7)

The mean sound velocity in each area is calculatedsequentially. Therefore, the mean temperature ofeach area is obtained by use of eqs. (2) and (7).

0.15

22.0

18.0

−1

Ref. 224.0Time (min)⎛t l t l ⎞cn = 2(ln − ln −1 )⎜⎜ n n − n −1 n −1 ⎟⎟ .
Ln −1 ⎠
⎝ Ln

0.2

26.0

20.0

The general form of eq. (4) is expressed as

3.

28.0

Ref. 8

A-D/D-A
converter

PC

Fig. 2 Experimental setup. Vertical temperature distribution
was measured by three sound probes.

References
1. G. C. Bakos, E. Tsioliaridou and N. F. Tsagas:
Energy Build. 38 (2006) 45.
2. I. Saito, N. Wakatsuki, K. Mizutani, M. Ishii, L.
Okushima and S. Sase: Jpn. J. Appl. Phys. 47(2008) 4329.
3. K. Mizutani, S. Kawabe, I. Saito and H.
Masuyama: Jpn. J. Appl. Phys. 45 (2006) 4516.
4. K. Kudo and K. Mizutani: Jpn. J. Appl. Phys. 43(2004) 3095.

1P2a-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 75- 76
11-13 November, 2008

Preconsolidation stress determination of clay
by using ultrasonic waves
Hyung-Koo Yoon 1‡, Joon Han Kim 1, Young-Uk Kim 2, Jong-Sub Lee1
(1 Korea University, 2 Myongji University)

1.

Introduction

When the load or stress is applied, soil starts
to deform. The vertical deformation under no lateralstrain is related to the compressibility of the soils.
The compressibility increases dramatically at
preconsolidation stress. The preconsolidation stressis the maximum stress, which was applied into thesoil.
Many methods, such as Casagrnade andOnitsuka methods, have been proposed to evaluate
the preconsolidation stress. These methods use theglobal settlement without considering the
micro-strain behavior. In this paper, the new method
for the evaluation of the preconsolidation stressusing ultrasonic shear waves is suggested. This
paper includes, the currently used methods for thepreconsolidation stress evaluation, the new method,experiments, result analyses, and conclusion.
2.

Preconsolidation stress evaluation

The preconsolidation stress has been
evaluated by several methods, such as Casagrande,
Janbu, Onitsuka, and so on. One of the mostcommonly used methods is the Casagrande method[1]. Casagrande method is based on the void ratio eand the vertical effective stress p' in logarithmic
scale (log). The void ratio is the ratio of the net
volume of the void to the total solid volume.
Because the lateral strain is not allowed in thissystem, the void ratio is directly calculated bymeasuring the vertical settlement. In e-log p' curve,
the minimum radius of curvature is selected; thehorizontal and tangential lines are drawn at theminimum radius; the bisector line between
horizontal and bisector lines is drawn; and thetangential line is drawn in e-log p' curve. Theintersection is preconsolidation stress. This method,
however, is user dependent. The Casagrande
method produces 15~50% higher value [2].
Janbu proposed the constrained modulus
method. The constrained modulus M is thereciprocal value of the column compressibility
coefficient mv (M=1/mv). The huge drop of theconstrained modulus, which is the breakdown ofsoil resistance stress, captures the preconsolidationstress. The Janbu’s constrained modulus method ismainly used for the high sensitive and low
overconsolidation ratio(OCR) clay.
Email: jongsub@korea.ac.kr

Another method was suggested by Jose [2].
In Jose’s method, log e is used instead of e in e-log
p' curve. The Jose’s method determines thepreconsolidation stress based on the intersection
between pre-yield and post-yield. The Jose’s
method was modified by Onitsuka [3]. Onitsuka use
ln(1+e)-log p' instead of log e-log p' to avoid thenegative value in void ratio term. The
preconsolidation stress in Onitsuka method is theintersection of pre-yield and post-yield lines. It is
known that the Onitsuka method produces the mostprecise preconsolidation stress.
3.

Shear wave velocity method

The previous methods are based on the void
ratio, which reflects the global vertical settlement.
The global vertical settlement results in therearrangement, rotation, and sliding of particles.
The strain level of the global vertical settlement ismiddle strain.
The small strain instead of the middle or large
strain may be captured by the ultrasonic waves. The
ultrasonic waves in this study are shear waves,which can capture inter-particle contact behavior.
The inter-particle contact behavior changes
dramatically at the preconsolidadtion stress because
the inter-particle forces such as cementation or
bonding are broken. The shear wave velocity versus
the vertical effective stress (Vs-log p') is plotted
during consolidadtion test. Vs-log p' produces thebilinear curve and intersection of the bilinear curveis corresponding to the preconsolidation stress. At
the preconsolidation stress, inter-particle contact
starts to break. Thus, the shear wave velocity
method considers the small strain inter-particle
contact behavior.
4.

Experiment program

A series of the verification tests are carriedout by using undisturbed specimen obtained atIncheon(I), Busan(B) and Kwangyang(K) in Korea.
The conventional oedometer cell, which is equippedwith bender elements, is used to measure thesettlement and the shear wave velocity. Note thebender elements are double-layer PZT elements.
The dimension of oedometer cell is 74mm indiameter and 63mm in height. And the benderelement is 11 mm in length, 4 mm in width, and 0.6
mm in thickness. For the generation and detection

of the shear waves in the soil, the signal generator,
filter-amplifier, and oscilloscope are used.
After soil specimen is placed into theoedometer cell, the normal stress is applied. The
load increment ratio is about one. Each loading
steps is about 24~48 hours to ensure the dissipationof the all excess pore pressure when the settlement
does not proceed after the dissipation of the excess
pore pressure, the vertical settlement and shear
waves are measured.

velocity. The currently used method evaluates thepreoconsolidation stress based on the global verticalsettlement. The preconsolidation stress by the shear
wave velocity is the intersection point at thebilinear curve of Vs-log p'. The preconsolidationstresses estimated by the new shear wave velocity
method produce the very similar values evaluatedby the Onitsuka method, which yields the almost
real preconsolidation stress. This study confirmsthat the new method is simple, easy, and producing
the reliable preconsolidation stress.
(a)5. Analyses of experimental results

6 kPa

6 kPa

11 kPa

11 kPaTime [ms]

1.0

1

(c)

10

100

1000

10000

log p'

240
180

631 kPa

2

0

0

0.5

1

1.5

2

Post-yield

120

Pre-yield

60

Pc= 30kPa

Time [ms]0Fig. 1 Measured shear wave signatures: (a) Incheon ; (b)Busan.

The evaluation of the preconsolidadtion
stress is demonstrated in Fig. 2 by using Casagende,
Onitsuka, and shear wave velocity methods for
Incheon clay. The preconsolidation stress evaluatedby the shear wave velocity method is almost
identical with that estimated by Onitsuka method.
The Casagrande method, however, produces thehighestpreconsolidationstress.
The
preconsolidation stresses evaluated by threemethods are summarized in Table I. Table I
confirms again that the Onitsuka and shear wave
velocity
methodproducethesimilarpreconsolidation stress, and the Casagrande method
yields the highest value.
6.

Post-yield

Pre-yield

0.6

Pc= 30kPa

Vs [m /s]

1.5

10000

315 kPa

315 kPa

1

1000

0.4

158 kPa

158 kPa100

0.8

80 kPa80 kPa

0.5

(b)

10

log p'

41 kPa

41 kPa0

1

21 kPa

21 kPa0.8

Pc= 34kPa

P′
2 kPa

(b)

1.2

0.4

ln(1+e)

P′
2 kPa

(a)

void ratio

At each loading stage, the vertical settlement
and shear waves are measured. The measured shear
wave signatures are plotted in Fig. 1 for clays
obtained at Incheon and Busan. As the verticaleffective stress p' increases, the first arrival of shear
waves decreases and the resonant frequency
increases.

1.6

Conclusion

This paper reviews the preconsolidationstress evaluation methods, which are commonly
used, and new method using ultrasonic shear wave

1

10

100

1000

10000

log p'

Fig. 2 Determinating preconsolidation stress at Incheonsite: (a) Casagrande; (b) Onitsuka; (C) shear wave
method.
Table I. Preconsolidation stress comparison.
Site

depth

Casagrande

Onitsuka

Shear wave

I6m

34 kPa

30 kPa

30 kPaB

10m

28 kPa

19 kPa

18 kPaK

3m

20 kPa

18 kPa

18 kPaReferences
1. A. Casagrande: BSCE, April(1932) 72.
2. B. T. Jose, A. Sridharan and B. M. Abraham:
ASTM. 12(1989).230.
3. K. Onitsuka, Z. Hong, Y. Hara and S. Yoshitake:35(1995).61.

1P3-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 77- 78
11-13 November, 2008

Nondestructive Evaluation of Compound Weld Defectby Photoacoustic Microscopy
光音響顕微鏡による複合溶接欠陥の非破壊評価
Daijiroh Shiraishi†, Haruo Endoh and Tsutomu Hoshimiya (Facult. Eng., Tohoku
Gakuin Univ.)
白石大二郎，遠藤春男，星宮務 （東北学院大 工）

1. Introduction
In indutry, the nondestructive inspection(NDI) of the existence of surface and internal
defects at their early stage has become more andmore important. The photoacoustic microscopy(PAM) 1) has been applicable to the NDI at thecircumstance in which the X-ray penetration orintersectional side-view inspection is not available
but front-view illumination is only available.
In this paper, nondestructive evaluation ofcompound defect in weld metal of aluminum plates
was carried out using PAM and the results werecompared with those obtained by the X-ray
micrograph obtained by tomography and thescanning laser microscope (SLM).

40
25
z

3

y

Unit (mm)Weld Metalx
Fig. 1 Schematic drawing showing specimen preparation
Measuring object area by the PAM

2. Experimental Apparatus and Specimen

E-mail : enpal@tjcc.tohoku-gakuin.ac.jp

Surface defect1mm(a) xy-plane view from z-direction

1mm(b) xz-plane view from y-direction
Fig. 2 Photograph of compound weld defect by thelack of joint penetration by X-ray permeation testing
500μm

500μm

The basic arrangement of the PAM systemconstructed for this experiment is the same as that
described in a previous publication.2) The
specimens used in the experiments were aluminum
plates. The aluminum specimen sampled fromwelded plates was chosen to include the compound
weld defect in which the surface and internal
defects were combined together. Two 45 degree-cut
aluminum plates with the dimension of 25mm×40mm and a thickness of 4mm were welded alongy-direction as shown in Fig. 1. Reconstructed X-ray
tomographic images with the intersection of
xy-plane viewed from z-direction and xz-planeviewed from y-direction were shown in Figs. 2 (a)and (b), respectively. A dark area at the center ofthe X-ray photograph corresponds to the internal
weld defect located in the position of approximately
0.5mm depth from the specimen surface. The
region shown by the arrow in Fig. 2 (a) corresponds
to the measured area by the PAM. The dotted line
surrounded in the round in Fig.2 (a) shows
approximate position and size of surface defect. Fig.
3 shows the cross sectional view of the defectobtained by SLM measurement. The defect width,
length and depth are approximately 300μm, 530μm
and 790μm, respectively. Welded aluminum plate
was mechanically fined with the thickness of 3mm
and set in the photoacoustic (PA) cell.
------------------------------------------------------------

Fig. 3 Cross sectional view of the surface
defect obtained by scanning laser microscopy

350

In this study, we carried out thenondestructive evaluation of the compound defectgenerated by the welding by PAM, and compared
it with X-ray tomographic image and SLM. The
separation of surface and internal defects were well
performed by changing modulation frequency, andPAM measurement agreed well with X-ray
micrograph and SLM measurements.

B'

3.0

mm

2.0

A

A'

300
250
200
150
100

A

50
0.0

A'
0.6

1.2

1.8 2.4ｍｍ

3.0(b) Signal distribution
line A-A’

1.0350
1.0 B 2.0mm

Signal Intensity(μV)

0.0
0.0

3.0

(a) Amplitude image

300
250
200
150
100 B
50
0.0

B'
0.6

1.2

1.8
ｍｍ

2.4

3.0

(c) Signal distribution line B-B’
Fig. 4 PA amplitude image and signal distribution
for the specimen with compound weld defect(modulation frequencies: 90Hz)

Signal Intensity(μV)

3.0

2.0
mm

A'

A
1.0

0.0
0.0

1.0

mm

2.0

(a) Amplitude image

3.0

250
200
150
100
50

A

0.0

A'
0.6

1.2

1.8
ｍｍ

2.4

3.0

(b) Signal distribution line A-A’

Fig. 5 PA amplitude image and signal distribution
for the specimen with compound weld defect(modulation frequencies: 270Hz)
3.0

2.0
mm

The experiments were carried out at different
modulation frequencies to obtain the depth
profiling by changing the thermal diffusion length.
Fig. 4 (a) shows the amplitude image obtainedat the modulation frequency of 90 Hz for the
specimen for the compound weld defect in which
the surface defect combined with internal defectand the measured area was 3.0 mm× 3.0 mm. The
thermal diffusion length at the modulation
frequency of 90 Hz is about 566 μm. A bright areaat the center of the PA amplitude image in Fig.
4(a) corresponds to the compound weld defect. In
this amplitude image, a particularly round brightarea is the surface defect region. In the SLM
analysis result, the depth of the surface defect isabout 790μm from the specimen surface tointernal defect bottom. In the meantime, theinternal defect is detected by the X-ray analysis at
about 5mm depth. Therefore, the thermal diffusion
length is sufficiently long for the thermal wave topenetrate and reach the internal defect. In Fig. 4(a),length of the compound weld defect and size of thesurface defect were obtained. Figures 4(b) and 4(c)show the signal distributions along the A-A' line
and B-B' line of the PA amplitude image in Fig.
4(a), respectively. The size of compound defectlength is guessed again in Fig. 4(b), and it ispossible to estimate the measurement of thesurface defect in Fig.4(c). Fig. 5(a) shows the PA
amplitude image obtained at the modulation
frequency of 270 Hz for the same specimen for thecompound defect. Fig. 5(b) shows the signal
intensity distribution on the A-A’ line of the PA
amplitude image in Fig. 5(a). The thermal
diffusion length is approximately 327 μm. It isfound that the size of internal defect detected fromboth of Fig. 5(a) and (b) generally decreases. Fig.
6 shows the PA amplitude image obtained at themodulation frequency of 450 Hz for the specimen
for the compound defect and the thermal diffusion
length is about 253 μm. In Fig. 6, it is found that
the PA signal for the surface defect dominated in
the image.
4. Conclusion

Signal Intensity(μV)

3. Experimental Results and Discussions

1.0

0.0
0.0

1.0

mm

2.0

3.0

Amplitude image
Fig. 6 PA amplitude image and signal distribution
for the specimen with compound weld defect(modulation frequencies: 450Hz)

References
1. H.Endoh, Y.Hiwatashi and T.Hoshimiya: Jpn. J.
Appl. Phys. 36(1997)3312.
2. T. Hoshimiya and K. Miyamoto: Jpn. J. Appl.
Phys. 39 (2000) 3172.

1P3-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 79- 80
11-13 November, 2008

Relationship between Photoacoustic Spectra and Thermoelectric
Properties of Amorphous Si-Ge-Au Thin Film)/0-(+ Si-Ge-Au KO':59+.*,0&IGHB'
D6
Hiroaki Takiguchià, Makoto Abe, Yoichi Okamoto, Hisashi Miyazaki, and Jun Morimoto(Dept. of MSE, NDA)
F;

PAà, 1L

C#4N

Q2, 8=

1. Introduction
Recently, thermoelectric materials haveattracted great deals of attention from the point of
the saving energy and the environmental protection.
The thermoelectric power generation is thetechnique to use the wasted heat, which is
exhausted from electric power plants, factories, andauto mobiles.
The characteristicts of thermoelectricmaterials are evaluated by dimensionless figureof merit ZT= α2T/(ρκ), where α, T, ρ, and κ arethermoelectric
power, absolutetemperature,electrical resistivity, and thermal conductivity,
respectively. One of the criteria for the practical useof the thermoelectric materials is ZT >1. However,
the thermal conductivity of thin film is difficult tomeasure. Therefore, the power factor P = α2/ρ iscommonly used.
We
have
reported
extremely
large
thermoelectric power of Si-Ge-Au amorphous thinfilm which maximum ZT value reached around103.1,2) It was reported that quasi-stable amorphous
phase and/or mixture of microcrystal would be
responsible for the large thermoelectric power.3,4)
But the mechanism and appropriate composition
ratio of Si, Ge and Au were not clarified sufficiently.
In the previous paper,5) the compostion ratio of Si
and Ge was fixed, and photoacoustic (PA) spectra
and thermoelectric properties with various Au
concentration were measured.
In this paper, we show photoacoustic spectra
and thermoelectric properties with various Si andGe composition ratio, where the Au concentration isfixed at the value where the sign of a thermoelectric
power changed.
2. Experiments
The sample preparation procedure was almost
same as previous paper.5) Samples were prepared byalternate deposition of Si, Ge and Au in the ultrahigh vacuum system. The samples were deposited-------------------------------------------------------------g47097@nda.ac.jp@, >N?$M3E7J<R%

at room temperature. They have 4 layers of
Si/Au/Ge/Au as 1 period of deposition. The
artificial intervals and total number of periods were
kept in 10 nm and 30, respectively. The thickness ofthe samples was 300 nm. We denoted the samples
as (Si layer (nm)/ Au layer (nm)/ Ge layer (nm)/ Au(nm)/ number of intervals) = (x/ 0.2/ 9.6 -x/ 0.2/ 30),
where x ranged from 0 to 9.6.
The thermoelectric power and electricalresistivity were measured by four terminal methods
during annealing cycles. Annealing temperature
was set at 673 K, and one annealing cycle was heatup and cool down between room temperature and673 K at a rate of 10 K/min.
PA spectra were measured using gasmicrophone photoacoustic spectroscopy (PAS)system. The wavelength of excitation light wasscanned from 400 nm to 1600 nm with 5 nm step.
Measurements were carried out at room temperature.
3. Results and Discussion

Figure 1 shows Si concentration dependenceof electrical resistivity at the second annealing cycle.
The electrical resistivity decreases with Siconcentration increasing. However, the electricalresistivity of one sample of Si: 50 % was one orderof magnitude smaller than that of the other samples.
Figure 2 shows PA spectra of as-deposited
samples. Sample (5.3/ 0.2/ 4.3/ 0.2/ 30) has
electrical resistivity which smoothly depends on Si
concentration. Sample (4.8/ 0.2/ 4.8/ 0.2 /30) has
electrical resistivity around one order lower thanthat of the other samples. The peaks at around 1400
nm come from the absorption of surface adsorbed
water. The arrows indicate absorption edge
wavelength corresponding to amorphous Si.5) The
wavelengths are 1115 nm in sample (5.3/ 0.2/ 4.3/
0.2/ 30) and 930 nm in sample (4.8/ 0.2/ 4.8/ 0.2/30). The composition of two samples is almost thesame, but the wavelength is apparently different.
Figure 3 shows Si concentration dependenceof absorption edge wavelength of samples
corresponding to amorphous Si. The absorption
edge wavelength data could be separated into two10 -3

10 -4

10 -5

380 K
630 K
0

PA intensity (arb .units)
PA intensity (arb. units)(5.3/ 0.2/ 4.3/ 0.2/ 30)

Fig. 1 Si concentration dependence of electricalresistivity at second annealing cycle.
groups. In the samples which has longer
wavelength (marked by ÒAÓ), electrical resistivity
increases with Si concentration increasing. In the
shorter wavelength samples (marked by ÒBÓ),sample of Si: 70 % has electrical resistivity whichsmoothly depends on Si concentration, and sampleof Si: 50 % has lower electrical resistivity than theother samples.
These results would indicate existence of two
or more amorphous phases. When electrical resistivity
and absorption edge wavelength smoothly depend on
Si concentration, the single amorphous phase would
be formed, not multi phases. In the other case(electrical resistivity or the wavelength of sample
distinctively change with Si concentration), different
amorphous phase would be made. Especially, fromPAS measurements, the existence of different opticalband gaps was found. This fact suggests the formationof the other amorphous phases.
It is well known that substrate temperature
has large effects on the degree of crystallinity (orÒdegree of amorphousÓ) of deposited thin film. In
ref. 6, substrate temperature dependence of power
factor was reported. Even if samples had same
composition, thermoelectric properties changed
with changing substrate temperature. We deducedthatÒdegreeofamorphousÓ
influenced
thermoelectric properties. To control Òdegree ofamorphousÓ, the change of substrate temperature
would be effective.
4. Conclusion
Optical band gap changed when electricalresistivity changed distinctively. Therefore, theexistence of different amorphous phase could be
confirmed. Especially, the difference of opticalband gap by PAS suggested the existence of two or(4.8/ 0.2/ 4.8/ 0.2/ 30)

400

20
40
60
80
100
Si concentration (volume%)

800
1200
Wavelength (nm)1600

Fig. 2 PA spectra of as-deposited samples.

1200
PeakWavelength
wavelength(nm)(nm)

Electrical resistivity (Ωm)

10 -2

1100

A

1000
B
900
800

0

20
40
60
80
100
Si concentration (volume%)

Fig. 3 Si concentration dependence of absorption
band edge wavelength of amorphous Si.
more amorphous phase. Amorphous phase that wasappropriate to thermoelectric materials existed. To
control amorphous phase, the change of substratetemperature was one of the effective ways.
References
1. Y. Okamoto, H. Uchino, T. Kawahara, and J.
Morimoto: Jpn. J. Appl. Phys. 38 (1999) L945.
2. H. Uchino, Y. Okamoto, T. Kawahara, and J.
Morimoto: Jpn. J. Appl. Phys. 39 (2000) 1675.
3. K. Fukui, M. Nakamori, Y. Okamoto, and J.
Morimoto: Proc. 24th Int. Conf. Thermoelectrics,
2005, p. 172.
4. H. Takiguchi, Y. Okamoto, and A. Aruga: Jpn. J.
Appl. Phys. 46 (2007) 4622.
5. H. Takiguchi, Y. Okamoto, H. Miyazaki, and J.
Morimoto: Jpn. J. Appl. Phys. 47 (2008) 3980.
6. A. Miyata, Y. Sato, Y. Okamoto, T. Kawahara,
and J. Morimoto: Proc. 21st Int. Conf.
Thermoelectrics , 2002, p. 442.

1P3-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 81- 82
11-13 November, 2008

Detection and Analysis of Photothermal
Generated in Capillary Channel flow

Signalキャピラリー流路中の光熱変換信号の検出と解析
Satoshi Hirashima, Hitoshi Katae, Akira Harata(Univ. Kyushu, Development of Molecular and Material Sciences.)
平島諭，片江等、原田明 （九大院 総理工）

1. Introduction
Recently, microfluidic devices, called lab-on-chipor µ-TAS atracts great attention. These devices
have more advantages, include reduction of reagent,
reaction time, and cost than traditional devices.
Highly sensitive detection technique is necessary
for these devices, because smaller volume are
disadvantage to detect target chemical substances.
Laser induced fluorescence (LIF) method has
excellent sensitivity. However, the LIF can detect
only fluorescent chemicals; unfortunately mostchemicals
aregenerally
nonfluorescent.
Photothermal spectroscopy containing photothermallens (PTL) method is one of the most sensitive
detection methods for nonfluorescent chemicals1-2).
Conventionally, visible laser have been utilized for
excitation beam source of PTL system. Ultraviolet
excitation laser is desired to detect more kinds ofchemicals, which absorb only UV light and aretransparent to visible light. We designed andmanufactured
ultraviolet
excitation-visible
enhancement photothermal lens system utilized
ultraviolet excitation beam in the range of 212 to
220nm, and detected non-labeled amino acids inaqueous solution.3)
Ultraviolet laser excited PTL system enables todetect many nonfluorescent chemicals, while
separation techniques to distinguish many kinds ofnonfluorescent chemicals are desired. Highperformance liquid chromatography adapting
capillary channel flow and micro-separation column(µ-HPLC) is one of the separation techniques suited
to PTL. The linear flow rate of capillary channel
flow dominates sensitivity of PTL system andseparation performance. In addition to linear flow
rate, excitation beam chopping frequency isimportant factor, affecting thermal diffusion length,
signal amplitude, and back ground noise. In thiswork we investigated dependence of linear flowrate and chopping frequency on the PTL signal
2. Theory
Photothermal lens signal (S)can be written as

S∝

1
vf

(1)

v is linear flow rate, and f is excitation beam
chopping frequency.
3. Experimental
Syringe pump

Sample cell
Objective lensFaraday
isolator

Photo diode

Probe
laser

FilterLock-in
amplifier

RecorderConvex lens
Chopper

Excitation laser

Figure1. Schematic diagram of photothermal lensdetection system

Figure 1 shows the schematic diagram ofphotothermal lens system. It consisted of a diodelaser (λ=408nm) as excitation laser and a diodelaser (λ=682nm) as the probe laser. Excitation
beam irradiated the sample solution in the capirally
cell (ID 100µm) with a convex lens (focal length,
100mm). Photothermally generated heat in thesample solution was monitored with probe beam,
which was focused with an objective lens (x40).
Excitation and probe beams were crossed in thesolution. Reducing the reflected light of probe
beam is achieved with a Faraday isolator. The
light intensity was measured with a photodiode, and
the PTL signal intensity was measured with alock-in amplifier. The sample solution was run
through the sample cell at a linear flow rate of
3.5-35 mm/sec with using a syringe pump.
Chopping frequency of excitation beam wasadjusted 20-600 Hz with a function generator. All
experiments were carried out with rhodamine B inmethanol as the sample solution (sample
concentration, 14µM).

4. Results and discussion
300

Signal amplitude [uV]300

Signal amplitude [uV]4.1 Chopping frequency dependence

3.5mm/sec
7.1mm/sec
11mm/sec
14mm/sec
18mm/sec

200

100

20Hz
100Hz
200Hz

50Hz
150Hz

200

100

0
0

0.1

0.2

0.3

1/v [sec/mm]

0
0

0.02

0.04

0.06

1/f [sec]

Figure 2. Inverse of chopping frequency (f)dependence of signal amplitude(flow rate=3.5-18mm/sec)

Figure.2 shows chopping frequency dependenceof signal amplitude. Signal was average value
measured in 30 sec. In a high chopping frequency,
signal amplitude was inversely proportional tochopping frequency. This shows that increase of
chopping frequency decrease signal amplitude as
decreasing of irradiates time. In a low chopping
frequency, signal amplitude reached to a steadystate strongly affected by the flow rate. This is dueto heat diffusion form the excitation laser spot tothe surroundings and motion of the heated area.
4.2 Linear flow rate dependence
Figure.3 shows linear flow rate dependence of
signal amplitude. In a fast linear flow rate, signal
amplitude was inversely proportional to the flow
rate. This is because increase of the flow rateincreases the volume of the heated region. In aslow linear flow rate, signal amplitude reached to asteady state. This is due to a size balance of theheated volume and the thermal diffusion length.
4.3 Sensitivity and separation performance
To evaluate of sensitivity of system, back groundnoise was measured for 20-600 Hz of chopping
frequency, and for 3.5-21 mm/sec of linear flow rate.
This result shows that decreasing of chopping
frequency contributes increasing of backgroundnoise, while linear flow rate doesn’t effectFigure3. Inverse of linear flow rate (v) dependenceof signal amplitude(chopping frequency=20-200Hz)

background noise. Therefore, the optimum
chopping frequency is consider to 50-100Hz, andthe optimum linear flow rate is consider to slower
as possible. However a slow linear flow rate
contributes negative effects to separation
performance in µ-HPLC, photolysis of reagents,
and collection time of experimental data. Increaseof the capillary crosssection for the sample celldecrease collection time, while harms the separation
performance. We investigated effect of increasing
capillary crosssection on separation performance,
indicated that allowable maximum crosssection size
is lower than 960mm2.
5. Conclusion

To optimize experimental conditions ofphotothermal detection for a µ-HPLC separation
technique, chopping frequency of excitation beamand linear flow rate were investigated. It is showedthat decreasing of chopping frequency and linear
flow rate contributes is required to increase of
signal amplitude. Optimum chopping frequency is
considered to 50-100Hz to decrease back groundnoise. A slow linear flow rate with a large cross size
capillary cell is the best solution for thephotothermal detection. Optimization of flow
condition contributes development microfluidic
devices.
References
1. A. Harata, K. Fukushima, Y. Hatano,：Anal. Sci.,
18 (2002) 13.
2. S.Hirashima, A.Harata : Proc. Symp. Ultrason.
Electron., Vol.26,(2005) pp.333 16-18 Nov,2005
3. S.Hirashima, A.Harata：Jpn. J. Appl. Phys. 47(2007) 3970.

1P3-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 83- 84
11-13 November, 2008

Millisecond Brillouin Scattering Spectroscopy in Solidand Gas Materials
固体と気体のブリュアン散乱のミリ秒観察
Yasuo Minami‡ and Keiji Sakai(Inst. Indust. Sci., Univ. of Tokyo)
南康夫，酒井啓司（東大生研）

1. Introduction
We improved sensitivity of the millisecond
optical beating Brillouin spectroscopy, andobserved the Brillouin scattering spectra in solid(polymethylmethacrylate, PMMA) and gas (air)materials. Though the measurable sample has been
restricted to liquid materials due to poor scattering
efficiencies of solids and gases, it is now possible toapply the technique to all kinds of materials.
This technique enables us to observe slow
dynamics in frequency range from 3 MHz to 300
MHz in non-contact manner.
2. Experiment
The measurement were carried out with themillisecond optical beating spectroscopy.1) Figure.
1 shows the block diagram of the experimental
setup. The incident light and the reference lightintersect in the specimen. Then, the scattered light
collinear with the reference light is detected by ahigh-speed photo detector, and they make theoptical beating signal. The beating signal iscaptured by digital oscilloscope in time domain.
Finally, we obtain the power spectrum of thephonon by FFT of the signal.
To demonstrate the improved sensitivity, we
performed the millisecond Brillouin scatteringexperiments in PMMA as solid specimen and air as
gas specimen.
3. Results and discussions
Figure 2 shows the typical Brillouin peakobserved with the millisecond optical beating
Brillouin spectroscopy in PMMA. Since anincreased instrumental width would be dominant in
the Brillouin line, a typical spectrum of theBrillouin peak obtained is expected to be a curve ofGaussian shape.2) The scattering efficiency of thisspecimen is very poor and is about 1 5 of that of-----------------------------------------------------------------------------E-mail: yminami@iis.u-tokyo.ac.jp

Fig. 1 Block diagram of the millisecond opticalbeating Brillouin spectroscopy.

liquid. As shown in the figure, the observed
spectrum is well fitted by Gaussian curve
representing the instrumental broadening caused by
the focusing the Gaussian beams of the incident
and reference lights. We could improve thedetection sensitivity and determine the phonon
velocity within a few ms at the cost of decay
measurement. We observed the dispersion relationin PMMA over the wavenumber range fromk = 8.1 × 104 m −1 to k = 5.3 × 105 m −1 at 300 K
and the result is shown in Fig. 3. The solid line
shows the best fitted relation of ω = vk giving
2860 m s for PMMA. This phonon velocity
agrees with the value of 2770 m s obtained withthe conventional optical beating spectroscopy at
100 MHz.3)
We carried out the real time Brillouinscattering experiment also for air, and the typical
Brillouin peak observed is shown in Fig. 4. The
scattering efficiency of air is only about 1 100 ofthat of liquid. As shown in the figure, the observed
spectra are also well fitted by Gaussian curve. The
dispersion relation obtained for air at 300 K isshown in Fig. 5. The solid line shows the best fitted
relation of ω = vk giving 350 m s for air. Thisvalue is close to the literature value of 348 m s at
300 K.

Intensity (arb. u.)

Intensity (arb. u.)
25

30

35
40
Frequency6 (MHz)
x10

3.5

45

4.0
4.5
5.0
6
Frequency
x10 (MHz)

5.5

Fig. 4
Brillouin peak observed with themillisecond Brillouin spectroscopy in air. The whitesolid line is the best-fitted Gaussian curve. The
sampling rate and measurement time are 250 MS s
and 200 ms, respectively. The scattering
wavenumber is k = 8.1 × 104 m -1 .

Fig. 2 Brillouin peak in PMMA observed with themillisecond Brillouin spectroscopy. The white solidline is the best-fitted Gaussian curve. The sampling
rate and measurement time are 500 MS s and 10
ms, respectively. The scattering wavenumber is
k = 8.1 × 104 m -1 .

Frequency (MHz)Frequency (MHz)

30

200
150
100
50
0

20
10
0

0

1

2
3
4
5
5
Wavenumber (x10 /m)
Fig. 3 Dispersion relation of acoustic phonon in
PMMA obtained with the millisecond Brillouinspectroscopy over the wavenumber range fromk = 8.1 × 104 m −1 to k = 5.3 × 105 m −1 at 300 K.
The experimental points (□) are well fitted by astraight line, of which the gradient yields the phasevelocity, 2860 m s for PMMA.

0

1

2
3
4
5
5
Wavenumber (x10 /m)
Fig. 5 Dispersion relation of acoustic phonon in air
obtained with the millisecond Brillouin spectroscopy
over the wavenumber range from k = 8.1 × 104 m −1
to k = 5.3 × 105 m −1 at 300 K. The experimental
points (□) are well fitted by a straight line, of which
the gradient yields the phase velocity, 350 m s for
air.

Error in determining the phonon velocity at a
certain frequency can be estimated from the scatterof the data from the line, which is better than 3 %.

Ministry of Education, Culture, Sports, Science andTechnology of Japan. This work was also partly
supported by Research Fellowships of the Japan
Society for the Promotion of Science for Young
Scientists.

4. Conclusion
We performed millisecond observation of
Brillouin scattering from solid and gas materials
with optical beating method, and obtain appropriate
dispersion relations of them.
This technique is applicable to the observationof the dynamics of fast reaction and phasetransitions, and so on.

References
1) Y. Minami, T. Yogi, S. Mitani, and Keiji Sakai: J.
Appl. Phys. 102 (2007) 013111.
2) Y. Minami, T. Yogi and K. Sakai: Jpn. J. Appl.
Phys. 45 (2006) 4469.
3) K. Hattori, T. Matsuoka, K. Sakai, and K.
Takagi: Jpn. J. Appl. Phys. 33 (1994) 3217.

Acknowledgment
This work was partly supported by aGrant-in-Aid for Scientific Research from the1P3-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 85- 86
11-13 November, 2008

Cladding-Mode Dependence of Long-Period Fiber
Grating Vibration Sensor
異なるクラッドモード次数を用いた長周期光ファイバ
グレーティング振動センサの特性
Hiroyuki Somatomo, Atsushi Wada, Satoshi Tanaka and Nobuaki Takahashi(National Defwnse Academy)
杣友 宏行，和田 篤，田中 哲，高橋 信明 （防衛大学校）

1. Introduction

2. Operation Principle
In general, grating-based fiber-optic components,
in which periodic refractive index modulation isapplied to core of single-mode fiber, are divided
into two types, FBG and LPG. The period of therefractive index modulation is less than 1 μm for
FBG whereas for LPG the period is several tens ~hundreds μm. In typical FBGs, incident light wave
is totally reflected at the specific wavelength, Bragg
wavelength (λB), so that the there is a sharp spectral
dip in the transmittance at λB. On the other hand,
LPG has several dips in the transmission spectrum
due to mode-couplings from core-mode to leaky
cladding- modes. The wavelengths of the dips λ(m)p
are given by the following equation

λ(m)p = Λ (ncore − n(m)clad)(1)

where Λ is the period of refractive index
modulation, ncore and n(m)clad denote effective
refractive indices for core mode and m-th cladding
mode respectively. Since several cladding-modes
g46011@nda.ac.jp

Optical Source

TransmittanceIn recent years there has been attracted muchattention in application of fiber-optic sensors forenvironmental monitoring, smart structure, smart
manufacturing, and so on. This is because suchsensors have various practical advantages: low loss,
immunitytoelectromagnetic
interference,
distributed or quasi-distributed sensing capability,
etc [1].
In these circumstances we have proposed
various fiber-optic sensors using specially designed
fiber-optic component so-called fiber Bragg
gratings (FBGs) [2-3]. In addition, we havefabricated another type of grating-based fiber
components, long period fiber gratings (LPGs), andhave applied to fiber-optic sensors for vibration ofsolid and underwater acoustic waves. In the present
paper, we have investigated characteristics of LPG
depending on the order of cladding-mode and havedemonstrated sensitivity enhancement of LPG
vibration sensor.

ModulatedLight

λp
Wavelength

Fig.1. Principle of LPG vibration sensor.
exist in normal fiber, there are several dips in thetransmission spectrum.
Conceptual scheme for the operation principleof the LPG vibration sensor is shown in Fig. 1.
With reference to the figure, when a vibration isapplied to LPG, the grating period Λ as well as theindices ncore and n(m)clad change periodically due tothe vibration- induced strain. As a result, thespectral dip λ(m)p shifts periodically in wavelengthdomain. In this situation, if an incident light from alaser source of which wavelength is tuned to a slopeof a spectral dip is launched into the LPG, thetransmitted light through the LPG is modulated inintensity according to the vibration. Since theintensity modulation depends on strain-sensitivityof λ(m)p and gradient of the slope of the spectral dip,higher sensitive operation can be achieved by using
LPGs having steeper dips with high strain-sensitive
wavelength-shift for λ(m)p.

3. Experiment and Results
We fabricated LPG by illuminating 248 nm
KrF excimer laser light to a single-mode opticalfiber that was photosensitized with boron doping.
Figure 2 shows the transmission spectrum of
typical LPG we fabricated. In the figure, Dip1,
Dip2, and Dip3 denote the spectral dips due tomode couplings from core-mode to claddingmodes; the dips caused by higher cladding-modes

100

0
-5
-10
-15
-20

Dip3

-25
-30

Dip2

Dip1

-35
1100

1200

1300

1400

1500

1600

1700

Transmittance [%]Transmittance [dB]

5

80
60
40

Fig.2. Typical transmission spectrum of LPG.

LPG2

20
0

Wavelength [nm]

LPG1

1500

1510

1520

1530

1540

Wavelength [nm]

1550

1560

Fig.4. Transmission spectra of sensing LPGs.
Wavelength shift [nm]5Dip1(1200 nm)
Dip2(1300 nm)
Dip3(1570 nm)

4
3
2
1
0
0

500 1000 1500 2000 2500 3000 3500

Static strain [με]Fig.3. Strain-induced wavelength-shifts for
Dip1, Dip2 and Dip3.
appears at longer wave- length. The dependence of
wavelength shift of the dips on static strain applied
to the LPG is shown in Fig. 3. As can be seen fromthe figure, dip with higher cladding-modes showshigher sensitive wavelength- shift to applied strain.
In order to construct LPG vibration sensor, wefabricated two LPGs in which spectral dip isadjusted within a wavelength region of a tunable
laser we used, from 1520 to 1590 nm, by changing
Λ in the writing processes. As shown in Fig. 4.,
Dip2 is adjusted to 1525 nm for LPG1 and Dip3 is1538 nm for LPG2. For a demonstration of LPG
vibration sensor, LPG1 and LPG2 are exerted by a
PZT; LPGs are fixed to a rectangular type PZT(140×5×10 mm) and driven by sinusoidal electric
signal at its resonant frequency (10.22 kHz).
Typical sensor output using LPG2 is shown in
Fig. 4. As can be seen from the figure, waveform
due to applied vibration is observed clearly.
Comparing the sensor outputs between for LPG1and LPG2, the sensitivity of the sensor with LPG2
Table 1.
Sensing LPG

Characteristics of sensing LPG.
Strain sensitivity Slope (ΔT/Δλ)[%/pm][pm/με]LPG1 (Dip2)

0.86

0.0057

LPG2 (Dip3)

2.00

0.0100Fig.5. Waveform of sensor output using LPG2.
is about 4 times higher than that with LPG1. The
experimental result is in good agreement with therelationship estimated from the strain sensitivity of
the wavelength shift and gradient of the slope ofdips as indicated in Table 1. Accordingly, it was
confirmed that higher sensitive operation of LPG
vibration sensor can be achieved by utilizing thespectral dip due to higher cladding-mode.

4. Concluding Remarks
In this research, we have investigatedsensitivity of wavelength shift of spectral dip for
LPG depending on order of cladding modes inorder to enhance the sensitivity of LPG vibration
sensor. In addition, we have demonstrated thathigher sensitive operation can be achieved byadopting higher cladding-mode.

References[1] A.D. Kersey, M.A. Davis, H.J. Patrick, M.
LeBlanc, K.P. Koo, C.G. Askins, M.A. Putnam,
E.J. Friebele, J. Lightwave Technol. 15, 1442
(1997).
[2] N. Takahashi, K. Yoshimura, S. Takahashi, K.
Imamura, Ultrasonics 38, 581 (2000).
[3] S. Tanaka, T. Ogawa, H. Yokosuka and N.
Takahashi, Jpn. J. Appl. Phys. 43, 2969 (2004).

1P3-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 87- 88
11-13 November, 2008

Recognition of Wavelength-Multiplexed Hierarchical Labelwith Acoustooptic Waveguide Circuit
波長多重階層化光ラベルの音響光学導波路回路による認識
Nobuo Goto1†and Yasumitsu Miyazaki 2(1Univ. of Tokushima, Dept. of Optical Sci. & Tech.,2
Aichi Univ. of Tech., Dept. of Media Informatics)
後藤信夫1†，宮崎保光2（1徳島大

光応用工学科, 2愛知工科大 情報メディア学科）

High-speed optical processing for packet routing
can overcome bottleneck in large-capacity photonic
networks. In label routing networks, various label
processing methods have been proposed to use
effectively the potential of optical signal processing.
The authors have studied on collinear acoustooptic(AO) switches1,2 and applications to optical label
recognition.3-6 Since parallel combination of collinear
AO switches can handle wavelength-divisionmultiplexed (WDM) optical pulses, recognition for
optical labels encoded in spectral and time domains
can be realized. In this paper, we discuss recognitionof layer-structure labels for hierarchical routing
control.

c M , Nt

2. Routing in hierarchical network
Fig.1 illustrates an example of hierarchicalnetworks. In the layer-structure label routing network,
processing of the labels can be simpler and faster.

Layer 1
Layer 2 Router

RouterRouterLayer 2

RouterRouterRouterRouterRouter

Fig.1 Two-layer photonic network.
Recognitionof c 2m
F-F

Delay

F-F

F-F

F-F

c1m = c1k
Label
Extraction

OpticalSwitch (default)

c1m ≠ c1k

OpticalSwitchPort 1
Port 2
Port N

Local
network

Port 0(cut through to border router)Fig.2 Configuration of optical label router
goto@opt.tokushima-u.ac.jp

c1, Nt

c1,1

cid 2

cidM
Mth

cid1
1st

2nd

t

Δ tp

Nt Δ tp

MNt Δ tp

λM ,1 L λM , N λλ2,1 L λ2,N λ

Nt Δ tp

Nt Δ tp

λ1,1 L λ1, N λλ1,1Fig.3 Structure of layer label.
(Nt-1)Δ tp

SAW(code k)S1k ( z, t )(Nt-2)Δ tp

Divider

Δ tp

S2k ( z, t )mClabelC lm'(Nt-l’)Δ tp

WDM(λ1,…,λΜNλ)PD
ElectricalmultipliertMatchedoutputSlk' ( z, t )S Nk t ( z , t )[(M+1)Nt-1]Δ tp
Delay
lines

Only a partial label corresponding to layer 1 can beused for global routing, where the rest of detail label
information is used for local routing. A configurationof the optical label router is shown in Fig.2. The
extracted label of a packet is optically processed andthe label information is used to reconfigure opticalswitches to forward the packet. We consider M-layer
label as shown in Fig.3, where M identifying bits areplaced ahead of the routing coded labels. Each of the
N t-bit layered codes has different wavelengths. In thenext section, we discuss recognition of the partial
label.

RouterRecognitionof c1m

ID bits

1st Nt bit

Fig.4 Configuration of collinear AO processor.

Layer 1
RouterRouterc2, Ntc M ,1t

Layer 1
Layer 2

2nd Nt bit

Mth Nt bit

1. Introduction

3. AO processor and layer labels
An integrated-optic processor consisting ofparallel AO switches and delay lines is shown in Fig.4.
The incident label is divided into N t +1 pulse trains.
The partial labels or the whole label to be matched inthis device are represented by frequency-multiplexed

2

SAWs. The label pulse trains are wavelengthselectively switched and the outputs are balanced
detected with photodiodes (PDs). The electrical
output signals are electrically multiplied. The M
matched output pulses correspond to label matching ofeach layer codes.

Output Current

1
0
-1
-2
-3
-4
0

100

4. Simulation⎧⎛1 ⎞ ⎛ 0 ⎞ ⎛1 ⎞⎫⎪⎜ ⎟ ⎜ ⎟ ⎜ ⎟⎪c im = {a1 , a 2 , a 3 } = ⎨⎜ 0 ⎟, ⎜1 ⎟, ⎜1 ⎟⎬⎪⎜1 ⎟ ⎜1 ⎟ ⎜ 0 ⎟⎪⎩⎝ ⎠ ⎝ ⎠ ⎝ ⎠⎭ngth
Wavele

λ22
λ23

λ33
50

150

100

200

250

Time (ps)1.4

Output Current

1.2
1
0.8
0.6
0.4
0.2
0
200

100

200

300

Fig. 8 The output for matching the second unmatchedlabel.

routing in layer-structure networks. If only the firstpartial label is required as the routing information, theSAWs of just the frequencies corresponding to thefirst label are required. The output current for
matching the first label is shown in Fig.7. The signals
at the timing of the second and the third ID bits areminus current. Similarly, the output for matching thesecond label is shown in Fig.8, where the second label
is unmatched.

300

Fig.5 Incident pulse train of an optical label.

100

-3.5

5. Conclusions
We discussed optical label matching using an
integrated-optic device and an electrical multiplier. By
introducing WDM address bits and identifying bits,
partial label matching is performed. We will further
investigate the layer-structure routing.

λ21

Optical code

-2
-2.5

Time (ps)λ13

a1a1a1 a1a2a3 a1a2a3

-1
-1.5

0

1

λ32

0
-0.5

-4

λ110
λ12

λ31

0.5

-3

(1)

Optical incident pulses Em(t) are shown for the case of
Cm = (a1 , a1 , a1 ,a1 , a2 , a3 ,a1 , a2 , a3 ) in Fig. 5.
When the SAW represents a different code Ck= (a1 ,
a1 , a1 ,a2 , a2 , a2 ,a1 , a2 , a3 ), the output electricalpulse train is obtained as shown in Fig.6. Since thesecond partial label is different, no second pulse is
output. Thus, these code matching can be used for

0300

Fig.7 The output for matching the first matched label.

Output Current

As a numerical example, we assume a bandwidth
limited optical pulse train with pulse period 12 ps,
pulse width 5.9 ps, bandwidth 160 GHz and N t = 3.
The interaction length of collinear AO switch isassumed to be lSW = 16 mm. We assume an OOK
orthogonal code set as given by

0200Time (ps)300Time (ps)Fig.6 Output when the second partial label is unmatched.

References[1] T. Kondo, Y. Miyazaki and Y. Akao, Jpn. J. Appl.
Phys. vol.17, no.7, pp.1231-1243, 1978.
[2] N. Goto and Y. Miyazaki, Trans. IEICE Electron.,
vol.J86-C, no.12, pp.1272-1281, 2003.
[3] N. Goto and Y. Miyazaki, Jpn. J. Appl. Phys.,vol.44, no.6B, pp.4449-4454, 2005.
[4] N. Goto and Y. Miyazaki, Jpn. J. Appl. Phys.,vol.45, no.5B, pp.4625-4630, 2006.
[5] N. Goto and Y. Miyazaki, Jpn. J. Appl. Phys.,vol.46, no.7B, pp.4602-4607, 2007.
[6] N. Goto and Y. Miyazaki, Jpn. J. Appl. Phys.,vol.47, no.5, pp.3974-3979, 2008.

1P3-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 89- 90
11-13 November, 2008

Improvement of Diffraction Efficiency in Surface-AcousticWave-Driven Tandem Acoustooptic Frequency Shifter
弾性表面波を用いたタンデム音響光学周波数シフタの高効率化
Susumu Shinkai‡, Shoji Kakio, Yasuhiko Nakagawa, (Univ. of Yamanashi)
Takefumi Hara and Hiromasa Ito (Tohoku University)
新海 進‡，垣尾省司，中川恭彦（山梨大院・医工） 原 武文，伊藤弘昌（東北大院・工）the 3-output-ports type AOFS was designed on
128˚-rotated Y-cut LiNbO3 substrate for an optical
wavelength of 1.55 μm and SAW wavelength Λ of
32 μm (the driving frequency of 125MHz). The
analytical model in the diffraction region is shownin Fig. 1. An output port O2 which is not needed toobtain the doubly diffracted light was removed
from the waveguide pattern of the previous tandem
AOFS1. It can shorten the length of the straightwaveguide between the 1st and 2nd gratings. Byutilizing this margin, the length of a tapered
waveguide can be increased from 3.3 mm of theprevious tandem AOFS to 9 mm while the total
length size of 30 mm was maintained. As a result,the vertex angle of the tapered waveguide can be
decreased from 0.78° of the previous tandem AOFS
to 0.32°. It may improve a complicated opticalinterference4 in the tapered waveguide. Therefore,
the improvement of the diffraction properties can be
expected.

1．Introduction
The optical frequency of laser beam diffracted
by an elastic wave through an acoustooptic effect is
Doppler shifted by the acoustical frequency. Thisphenomenon can be used as an acoustooptic
frequency shifter (AOFS). However, the frequency
shift of a simple AOFS is almost fixed at around thecenter frequency of the transducer. To solve thisproblem, we proposed a monolithically integrated
tandem waveguide-type AOFS driven by a surface
acoustic wave (SAW) and observed frequency
shifted lights corresponding to sum of two driving
frequencies and the difference frequency.1
Moreover, using this tandem AOFS, thefrequency-shifted-feedback (FSF) fiber laser
oscillation was realized and an optical frequency
domain range was demonstrated.2 The practicalapplications of the FSF fiber laser with the tandem
AOFS, such as that to the optical three-dimensional
shape measurement with high accuracy,3 can be
expected upon increasing diffraction efficiency.
In this paper, to improve the diffraction
properties of the tandem AOFS, a novel waveguideshape, hereafter called “3-output-ports type”, wasdesigned and the diffraction properties were
simulated using the beam-propagation method(BPM).

3． Simulated Diffraction Properties
OptiBPM6.0 of Optiwave was used for the
analysis. Port I2 was defined as the input port and a
Gaussian beam with an optical wavelength of 1.55
μm and a beam waist diameter of 5 μm wasassumed as the incident light. The analysis of thediffraction properties resulting from the SAW was
performed by setting the refractive index grating
expressed as Δngsin(2πx/Λ) in the 1st and 2nd

2．Design of Tandem AOFS
As a tandem AOFS with a novel waveguide shape,
1st-GratingxyPort I1z

2nd-Grating
Lg

Grating Width Lg
Lg

Port O1

10μ m

100μm
Port O3

0.32°
125 μm

125 μm

250 μmIncident light
Port I2

L=4mm
L=4
Cross WG length L

1.27 °
Port O4
L =4 mm
30mm

Fig. 1 Analytical model of 3-output-ports type tandem AOFS.

-----------------------------------------------------------g08me017@yamanashi.ac.jp

Normalized amplitude of E y

Beam Power (Normalized)

1

Lg=2mm0.9: sin curve: O1: O3 (Diffracted)

0.8

0.09

2

: O2
: O4 (Undiffracted)

0.09

0.7

0.43

0.6

250

0.5

0.20

0.4
0.3

0

0.2

x
(μm)

0.1
0

0

1

2

3

4

-4

Δ ng in 2nd Grating (× 10 )

30
18

5

12
6

-250

z (mm)

0(a) Previous 4-output-ports type.

(a) Previous (4-output-ports) type.

1

Beam Power (Normalized)

24

1.0

2

Lg=2mm0.9: sin curve: O1: O3 (Diffracted): O4 (Undiffracted)

0.8
0.7

Normalized amplitude of E y

0.09

0.55

0.6
0.5
0.4

250

0.08

0.3
0.2
0.1
0

0
0

1

2

3

4

-4

Δ ng in 2nd Grating (× 10 )5(b) Novel 3-output-ports type.
Fig. 2 Simulated diffraction properties.

x
(μm)

30
24
18

1.0
12
6

-250

z (mm)

0(b) Novel 3-output-ports type.

AO interaction regions with the width Lg of 2 mm
for TM-mode propagation.
Figures 2(a) and 2(b) show the light powers ofPorts O1, O3, and O4 power as a function of Δng inthe 2nd grating at the maximum diffraction
efficiency by the 1st grating, in the previous
4-output-ports type and the novel 3-output-ports
type, respectively. The values of output beam power
were normalized by incident light power. The beam
power in Port O3 corresponds to the doubly
diffracted beam power. The maximum doubly
diffraction beam power was increased from 0.43 in
the previous type to 0.55. The minimum
undiffracted beam power in Port O4 was also
improved from 0.20 to 0.08.
Figure 3 shows the three-dimensional display ofthe simulated optical field distribution of Ey for the
maximum doubly diffraction efficiency. It can beseen that the beam power of the undiffracted beamin the 2nd grating was reduced by adopting the
3-output-ports type. It may be caused by decreasing
the vertex angle of the tapered waveguide because
the incident beam thorough the tapered waveguidecan generate the diffracted beam with themaintained equiphase surface in the 1st grating.
Moreover, an influence to other ports due to theremoval of the output port O2 was not observed.

Fig. 3 Amplitude distribution of Ey simulated by BPM.

4． Conclusions
The novel 3-output-ports type AOFS was
designed and the diffraction properties were
simulated. The diffraction properties were improvedby decreasing the vertex angle of the tapered
waveguide. The maximum doubly diffraction beam
power was increased from 0.43 in the previous type
AOFS to 0.55.
In the future, the novel tandem AOFS will befabricated and the optical diffraction properties will
be evaluated.
References
1. S. Kakio, S. Uotani, M. Kitamura Y . Nakagawa,
T. Hara, H. Ito, T. Kobayashi and M. Watanabe,
Jpn. J. Appl. Phys. 46 (2007) 4608.
2. S. Kakio, M. Kitamura, Y . Nakagawa, T. Haraand H. Ito, Jpn. J. Appl. Phys. 47 (2008) 3992.
3. C. Ndiaye, T. Hara, N. Hamada and H. Ito, Proc.
23rd Int. Laser Radar Conf. (ILRC23) 8O-1
(2006) 719.
4. S. Kakio, S. Uotani, Y . Nakagawa, T. Hara, H.
Ito, T. Kobayashi and M. Watanabe, Jpn. J. Appl.
Phys. 46 (2007) 669.

1P3-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 91- 92
11-13 November, 2008

Surface-Acoustic-Wave-Driven Acoustooptic Modulator
with Wide Wavelength Range for Visible Laser Light
弾性表面波を用いた広帯域可視光変調素子
Shoji Kakio, Susumu Shinkai, Hiroyuki Kawate and Yasuhiko Nakagawa(Univ. Yamanashi)
垣尾 省司，新海 進，川手 寛之，中川 恭彦（山梨大院・医工）

1. Introduction
The authors have proposed a waveguide-type
acoustooptic modulator (AOM) driven by a surface
acoustic wave (SAW) in a tapered crossed-channel
proton-exchanged (PE) waveguide on a 128° Y-cut
LiNbO3 substrate for an optical wavelength of 1.55
μm.1 One of the features of the waveguide-type
AOM is that it has a wide wavelength range
compared with a bulk-type AOM.2 By applying the
waveguide-type AOM to the visible range, an AOM
can be realized in which laser light of the three
primary colors of red, green, and blue can be
modulated by the same modulator.
In this paper, we first designed thewaveguide-type AOM and simulated the optical
diffraction properties using the beam-propagation
method (BPM). Next, the waveguide-type AOM
was fabricated and the optical diffraction properties
and the driving SAW power were measured.
2. BPM analysis
The overall configuration and the analyticalmodel used for the diffraction region of the
waveguide-type AOM are shown in Figs. 1 and 2,
respectively. Ports 1, 3, and 4 were defined as the
input, diffracted output, and undiffracted output
ports, respectively. The width of the waveguide ofeach port was designed to be 3 or 6 μm. Thesewaveguides were expanded to the waveguide width
W using tapered waveguides that crossed each otherwith the Bragg angle 2θB. The SAW wavelength Λwas designed to be 16 μm.
The extraordinary refractive index change Δne in
the waveguide was assumed to be 0.02. The Bragg
angle 2θB was determined by the optical wavelengthof blue light or the average wavelengths of red andB

B

Grating (Λ=16μm)
xyPort 2

Port 2
Port 1mm
12

Lg =2mm

PE waveguide

IDT (Λ=16μm)

128 Y-X

LiNbO
3
2 8m mFig. 1

Lg =1mm2θB= 0.84° or 0.70°mm

Port 4m Port 3

Undiffracted light

Diffracted light
8mm

Fig. 2 Shape of the diffraction region of waveguide-type AOM.
kakio@yamanashi.ac.jp

0.5

Port 40.2°------------------------------------------------------------μm

1μblue light, that is, green light. The refractive index
change was assumed to be induced by the SAW by
setting up a refractive index grating, which was
expressed as Δngsin(2πx/Λ). OptiBPM 6.0 of
Optiwave was used for the analysis. Optical
wavelengths of 633, 532, and 473 nm were used for
red, green, and blue light, respectively.
First, the leakage power of Port 3 without thegrating (Δng=0) was calculated. The leakage power
decreased with increasing waveguide width W. For
W>60 μm, the leakage power, which was
normalized by the input light power, was less than
1%. Therefore, W was designated as 60 μm and thelengths of the diffraction region on the waveguide L
for blue and green light were determined to be 4.1
and 4.7 mm, respectively.
Second, the output beam power P3 in thediffracted output port, Port 3, was calculated for
TM mode propagation as a function of theamplitude of Δng. Figure 3 shows the optical
diffraction properties for Lg=1 mm. The maximum
values P3max for optical wavelengths of 633, 532,
and 473 nm were 78, 77, and 65%, respectively.
The optical wavelength dependence of P3max isshown in Fig. 4, together with the experimental
results. The peak of P3max appeared at the optical
wavelength for which the Bragg angle wasdesigned.

Grating width Lg

Incident light 3 or 6μm

r6
3o

μm

Configuration of waveguide-type AOM.

W=60μmz Port 1

0
17

Bending part

Port 3

2

2: sin curve

0

1

3 -4

Fig. 3Calculated diffraction properties.

Δ ng× 10451
0.9 Lg=1mm
0.8
0.7
0.6
0.5
0.4
: 2θ B=0.70° for Blue, Calculation
0.3: 2θ B=0.70° for Blue, Experimental
0.2: 2θ B=0.84° for Green, Calculation: 2θ B=0.84° for Green, Experimental
0.1
0
400
450
500
550
600
650
700
Optical Wavelength (nm)Fig. 4Beam Power P 3 (Normalized)

Lg=1mm, 2θ B=0.84°:Red (633nm):Green (532nm):Blue (473nm)

P3max vs optical wavelength.

3. Experiment
The channel waveguide was fabricated by first
forming an RF-sputtered SiO2 mask with a film
thickness of 0.25 μm by the liftoff method on a
128° Y-cut LiNbO3 substrate followed by the PE
process and postannealing. The PE was carried out
for 4 min in a solution of benzoic acid containing
0.2 mol% lithium benzoate at 240°C, and theannealing time was 2 h at 400°C. A Gaussian index
profile with Δne=0.02 and a waveguide depth of 1.0
μm were obtained.
After polishing the end face of the waveguide, apair of normal interdigital transducers (IDTs) with aperiod length Λ of 16 μm and an overlap length Lgof 1 (30 finger pairs) or 2 mm (20 finger pairs) wereformed on the substrate. A red (633 nm), green (532nm), or blue (473 nm) laser beam was guided into
the end face of the PE waveguide through an
objective lens with a magnification of x40. The
diffracted light power as a function of the input
voltage of an RF burst signal of 245 MHz wasmeasured using a photomultiplier. Figure 5 shows
the measured diffraction properties for Lg=1 mm.
The measured P3 was normalized by the output
light power in Port 4 without an input voltage.
The peak diffraction efficiencies for optical
wavelengths of 633, 532, and 473 nm were 85, 82,
and 47%, respectively. As shown in Fig. 4, for
optical wavelengths of 633 and 532 nm, similar
optical wavelength dependences to those in theanalytical results were obtained. On the other hand,

1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

Lg=1mm, 2θ B=0.84°:Red:Green
:Blue

0

2

4

Fig. 55

SAW Power P100 (mW)Beam Power P 3 (Normalized)
max

Beam Power P3

1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

2

: sin curve

6 8 10 12 14 16 18 20
Input Voltage (Vrms)

Measured diffraction properties.

2θ B=0.84° for Green3: Lg=1mm, Experiment: Lg=2mm, Experiment

10

5

2

10

5

: Lg=1mm, Theory: Lg=2mm, Theory

1

10

5

400

450

500
550
600
650
Optical Wavelength (nm)700

Fig. 6 SAW power P100 vs optical wavelength.

compared with the analytical results, the maximum
diffraction efficiency for the optical wavelength of
473 nm was relatively small.
Figure 6 shows the optical wavelength
dependence of the measured driving SAW power(P100) required to obtain the maximum diffraction
efficiency. The theoretical results obtained fromcoupled-mode theory3, in which a planar waveguide
was assumed, are also shown in this figure. The
values of the experimentally obtained P100 were anorder of magnitude larger than the theoreticalvalues. The causes of the difference between thetheoretical and experimental values in the
waveguide-type AOM will be investigated.
4. Conclusions
The diffraction properties of a waveguide-type
AOM were evaluated. For 633 and 532 nm,
according to the analytical results, a maximum
diffraction efficiency ranging from 74 to 85% was
obtained. On the other hand, in contrast with theanalytical results, the maximum diffraction
efficiency for 473 nm was as small as 47%. The
values of the P100 were an order of magnitude larger
than the theoretical values.
References
1. S. Kakio et al, Jpn. J. Appl. Phys. 42 (2003) 3063.
2. S. Kakio et al, IEICE Trans. J-86-C (2003) 1263
[in Japanese].
3. K. W. Loh et al, Appl. Opt. 15 (1976) 156.

1P3-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 93- 94
11-13 November, 2008

Fabrication of Magneto-optic Thin Films on LiTaO3 and/or
LiNbO3 Substrates by Contact Epitaxy
LiTaO3 および LiNbO3 基板上へのコンタクトエピタキシーによる磁気光学薄膜の形成
Hiroyuki Tashiro1†, Satoru Noge2 and Takehiko Uno1 (1 Facult. Eng., Kanagawa Inst.
Tech, 2 Numazu Nation. College Tech.)田代博之 1‡，野毛悟 2，宇野武彦 1 （1 神奈川工大 工; 2 沼津高専）

1. Introduction
We propose multifunctional thin films for
integration of optical and acoustic-wave devices.
LiTaO3 (LT) and LiNbO3 (LN) crystals have been
widely utilized for piezoelectric and electro-optical(EO) devices. However, magneto-optical devices
have not been realized on LT and/or LN substrates.
Because the magneto-optical (MO) effect exists inspecial materials such as YIG (yttrium iron garnet),integration of MO and EO or acousto-optical (AO)
effects is difficult to realize.
We have been studied a method to control crystal
orientations of thin films by contact epitaxy
method1). By this method, we obtained cerium
substituted yttrium iron garnet (Ce:YIG) films withlarge Faraday rotation on silica glass substrates.
Furthermore, we observed a sign of orientation
control for LiNbO3 thin films. In this paper, we
discuss the possibility of integration of EO, AO andMO effects on LiTaO3 and/or LINbO3 substrates.
2. Cerium substituted YIG films
We investigated fabrication of cerium substituted
yttrium iron garnet (Ce:YIG) film on LT and/or LN
substrates. It is well known that YIG (Y3Fe5O12)
have a superior Faraday rotation for visible light.
However, the Faraday rotation of YIG is not solarage for use of thin-film type MO devices. To
improve Faraday rotation characteristic, bismuth
substituted or rare-earth matal substituted YIG havebeen
developed.
Ce
substituted
YIG2-4)(CexY3-xFe5O12) is one of the promissing materials
for a thin-film MO device in near-infrared band.
Ce:YIG with a large substitution amount canfabricate by thermal nonequilibrium processes suchas sputtering deposition. Therefore, Ce:YIG can beobtained in the form of thin films. To obtain asuperior MO characteristic, single crystal thin filmof Ce:YIG is needed, and epitaxial growthtechnique of Ce:YIG on gadolinium-gallium-garnet(GGG) substrate had been established4). To realize
thin-film type MO devices, a method to fabricate-----------------------------------------------------------hiloyuki@ele.kanagawa-it.ac.jp

single crystal films on various substrates must be
developed. We have been studied a method tocontrol film orientation deposited on silica
substrated. We call the method “contact-epitaxy”
and a sign of epitaxial growth of Ce:YIG on silica
glass have been obtaied1).
By use of the contact-epitaxy technique forfabrication of Ce:YIG on LT and/or LN substrates,
multifunctional thin films of EO, AO and MO
effects may be realized.
3. Configuration of the film
Figure 1 shows a configuration of a Ce:YIG film
on a LT or LN substrate. The Ce:YIG thin film is
not directly formed on the substrate, but a very thin
SiO2 layer is interleaved between the substrate andthe film. The SiO2 layer prevents the affect of thesubstrate on crystallization of the film during
thermal treatment process of contact-epitaxy.
Furthermore, it suppresses the diffusion of Li to thefilm. The thickness of the SiO2 film must be thinenough to avoid optical and mechanical affects.

Magneto optical thin film (Ce:YIG)

SiO2 layer
LiTaO3 or LiNbO3
substrate

Fig. 1

Configuration of the MO film on LT
or LN substrates.

To utilize the Ce:YIG film as optical wave-guide,refractive index of the film, nf, must be larger thanthat of the substrate, ns. Refractive index of
Ce1Y2Fe5O12 is 2.21, and the indices for LT and LN
are,
LT: no=2.178, ne=2.18
LN: no=2.29, ne=2.20.
Therefore, optical wave-guide can be formed on
LT substrates. To utilize acousto-optical effect, LT
substrate of around 124˚ or 36˚ rotated Y-cut

Ce:YIG(opt. guide)

free

4000

1

LT substrate

Subst. : LT 36˚RY
Film: YIG

2

4
5

Fig. 4

3500

Electric field distribution of TE-mode.
(Calculated)
Film thickness: 1.2 m,=1.55 m3250

Fig. 2

1

metallized

3750

3000

0.2 0.4 0.6 0.8

3

4250

SAW velocity (m/s)

Electric field (TE-mode)0x (micron)(RY-cut) is suitable. In 36˚ RY-cut LT substrate,
leaky SAW having a large electromechanicalcoupling constant is excited5), and propagation loss
is small enough for practical use. Dependencies of
SAW velocity and electromechanical coupling
constant on the film thickness are shown in Figs. 2
and 3.

00.2

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
kH

Dependency of SAW velocity on
Ce:YIG film thickness.

0.1

Vacuum chamber(a)Sputtered film
(Amorphous)

Subst. : LT 36˚RY
Film: YIG

0.08

plasmaLT
substrate
Ar gask2

0.06

ElectrodeSinglecrystal chip
(GGG)
Vacuum pump

(b)

0.04

Electrode

0.02
0

0

0.2 0.4 0.6 0.8

1
kH

1.2

1.4 1.6

1.8

2

Fig. 3 Dependency of coupling constant on
Ce:YIG film thickness
For a case of 1.2 m film thickness, kH=1.5 for1GHz. In this case coupling constant of about 0.04
can be obtained.
Figure 4 shows an example of field distribution
for TE-mode guided light. From this distribution,
control of the guided light wave by EO, MO andAO effects will possible with enough efficiency.
4. Fabrication technique
The Ce:YIG films can be fabricated by thecontact-epitaxy shown in Fig. 5. Both of (100) and(111) direction Ce:YIG films having high Faraday
rotation constants are possible to prepare.
5. Conclusion
We have basically studied multifunctional films
having EO, MO and AO effects.
Ceriumsubstituted YIG films on rotated Y-cut LiTaO3
substrates will be a suitable configuration for it.
Acknowledgement
This work is supported by a Grant-in Aid for Scientific
Research from the Japanese Ministry of Education,

Ar gas(c)

Vacuum pump

HeaterElectrode

Pressure

Fig. 5.

Vacuum pump

Fabrication process by the contactepitaxy

Culture, Sports, Science and Technology.

References
1. T. Uno, S. Ohta and S. Noge: Int. Conf.
Electroceramics, (2003, Boston) OS2-CRY-4-0.
2. M. Gomi, K. Satoh and M. Abe: Proc. Fifth
Intern. Conf. Ferrites (1989, India) p.919.
3. T. Shintaku and T. Uno: J. Appl. Phys. 76(1994)
8155
4. A. Tate, T. Uno, S. Mino, A. Shibukawa, and T.
Shintaku: Jpn. J. Appl. Phys. 35(1996), 3419.
5. K. Nakamura, M. Kazumi and H. Shimizu: Proc.
IEEE Ultrason. Symp.(1997) p.819

1P4-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 95- 96
11-13 November, 2008

Propagation Characteristics of Substrates for
Lamb Wave Type Elastic Wave Devices
ラム波型弾性波素子基板の伝搬特性
Hitoshi Yoshida, Yasuhiko Nakagawa and Shoji Kakio ( Interdisciplinary Graduate
School of Med. Eng., Univ. of Yamanashi )吉田斉師，中川恭彦，垣尾省司 (山梨大院 医工）

1. Introduction
Quartz is a physically and chemically stable
crystalline substrance. It has been used as a crystal
occilator that is little affected by aging. It is also
widely used in devices such as a frequency
generator becausse quartz operates stably with very
little thermal frequency shift compared with othersubstances.1,2) Therefore, putting an oscillator and aresonator to practical use as an electronic device
requires stable operation with good frequencytemperature characteristics. In recent studies,
researchers have specifically examined a plate wave
propagating on a quartz substrate.3,4,5) The
characteristics of this Lamb wave type substrate
include the following: it performs high frequency
operations with phase velocity that is 2-3 times
higher than that of a surface acoustic wave (SAW);
it allows easy excitation and reception with agreater electromechanical coupling coefficient (K2);and it has an extermely high coefficient ofreflection from reflectors such as a grating on the
propagation path.
We aim at exploiting the application of a
substrate for Lamb wave type acoustic wave
devices and the frequency-temperature characteristics of Lamb wave propagating on a quartz
substrate were discussed theoretically.
2. Theoretical Analysis
Fig.1 shows the coordinate system employed forLamb wave analysis. The Lamb wave to beanalyzed is presumed to propagate along the x1
direction, and the direction perpendicular to thesubstrate surface was set as the x3 direction. The
substrate thickness was set to H, and wave analyses
were conducted. A wave propagating in apiezoelectric medium must satisfy the piezoelectricbasic equation, and satisfy the equation of motionand Laplace’s equation shown below.

 2u j
t 2

E
 C ijkl

 2uk
 2
 ekijxi xl
xi x k

(1)

 2uk
 2
S
eikl
  ik0xi xl
xi x k(2)

Particle displacement and electric potential wereassumed as a solution set of equations (3) and (4).

u j   j expikbx3  ikx1  it (3)   4 expikbx3  ikx1  it (4)Equations (3) and (4) must satisfy equations (1) and(2). Therefore, the latter are substituted into theformer. Furthermore, theoretical analysis was
conducted under eight boundary conditions: particle
displacement, stress, electric displacement and thecontinuity of electric potential at the top and bottom
surfaces of the substrate.
As for frequency-temperature characteristics,
assuming a phase velocity at 20 degrees Celsius andan arbitrary temperature as v0 and vt, respectively,
frequency variation is expressed as follows:f vt  vo


fo
vo

(5)

where  is the expansion coefficients at thetemperature t = 20 °C, respectively.

X3

X2

X1
Substrate
X3=-H-----------------------------------------------------------nakagawa@es.yamanashi.ac.jp

Fig. 1

Coordinate system used for analysis.

Table I

Euler angles (λ, μ, θ) [°]v [m/s]K2 [%]
Δf/f [ppm］
H/Λ
PFA [°]New Cut 1(22.95, 124.9, 42.2)
3804
0.107
0.7
0.968
-25.66

NewCut1
NewCut2
NewCut3

 f/f [ppm]

1

3

0
1
2

-1

-2

-20

Conclusions

In this paper, searching new cuts with excellent
frequency-temperature characteristics of Lambwave propagating on a quartz substrate wereconducted. Three new cuts with excellent cubic
frequency-temperature characteristics were developed by theoretical analysis and these frequency
variation were about 1 ppm. Experimental value of
New Cut 2 was well in agreement with theoretical
calculation at  = 7.45 °. Consequently, change in 
by 0.05 ° proves to provide more favorable
temperature characteristics.

2040o
Temperature [ C]6080

Fig. 2 Theoretical analyses results offrequency-temperature characteristics

20

10

0
exp.
o
cal.( =7.5 )ocal.( =7.45 )

-10

-20

5.

0

Measurement Result of New Cut 2

Measuring element was made, forming aninterdigital transducer (IDT) on a New Cut 2 quartz
substrate using photolithographic technique.
Frequency response was measured using a network
analyzer. The temperature was changed from -20 to
80 °C at steps of 5 °C.
Comparing measurement and theoretical analysis
were shown in Fig.3. It shows experimental value
was not as good as the calculated value. However
the experimental value was well in agreement withtheoretical calculation at  = 7.45 °. Consequently,
change in  by 0.05 ° proves to provide morefavorable temperature characteristics.

New Cut 3(90.0, 14.715, 0.0)
3775
0.115
1.22
1.010
-25.22

2

Theoretical Analysis Results

Three new cuts with excellent cubic frequencytemperature characteristics were discovered.
Theoretical analysis results of frequencytemperature characteristics for three cuts wereshown in Fig.2. It shows complete third order curve
and these frequency variation were about 1 ppm.
The characteristics of three new cuts were shown in
Table I.
4.

New Cut 2(90.0, 18.997, 7.5)
4296
0.130
1.37
0.900
-18.00 f/f [ppm]3.

Characteristics of three new cuts

0

20
40o
Temperature [ C]60

80

Fig.3 Comparing measurement and theoreticalanalyses of frequency-temperature characteristics

References
1. H. F. Tiersten: J Acoust. Soc. Am. 59 (1970) 879.
2. M. Matsusita, H. Yao, K. Goohara, I. Hatta andN.; Kato: J. Phys. Soc. Jpn. 54 (1985)
3. Y.Nakagawa, S. Tanaka and S. Kakio: Jpn. J.
Appl. Phys. 42 (2003)
4. Y.Nakagawa, M. Momose and S. Kakio: Jpn. J.
Appl. Phys. 43 (2003)
5. Y.Nakagawa, M. Shigeta and S. Kakio: Jpn. J.
Appl. Phys. 45 (2003)

1P4-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 97- 98
11-13 November, 2008

Matrix Formulation for Calculating Spatial Transfer Characteristics in Mechanical Impedance Mismatch System
機械的インピーダンス不整合系における空間伝達特性計算の行列定式化Michio Ohki (Natl. Def. Acad.)

大木 道生（防大）1. Introduction
It is practically important and useful to analyze avibration system with some mechanical impedancemismatch layers inside the system, using a simple
and systematic mathematical method. We have already treated such a system with the following tactics:1,2) The system is always regarded as a
2N-layered system (N=1,2,...), and the way of
propagation, reflection/transmission, and input/output of the wave inside the system are represented with some matrix operations. A multiplication of the matrices in appropriate order representsa path of energy flow, and the sum of these paths,
represented with a kind of infinite geometric seriesof matrices or “Neumann series”, is interpreted as aprobabilistic superposition of energy modes, whichenables us to obtain characteristics of frequency
response1) or impulse response2), according to theway of superposition.
It is also important to investigate the spatial
shape of a mode, for example, the positions ofnodes and loops, which influence a spatial transfer
frequency response when a (pinpoint) transmitterand receiver are located on the system. However, ingeneral, such an analysis requires matrices of larger
size, as its spatial resolution is improved.
In this study, we adopt a concept of “spatial dipole delta function” discussed in ref. 3 along withthe foregoing tactics for that purpose. Then, the spatial transfer function can be obtained using(2N+4)-by-(2N+4) matrices for 2N-layered system,and the matrix size does not enlarge, even if the sizeof a transmitter and receiver becomes smaller.
2. Matrix Construction and Operation
We consider an example of 2N-layered system,
as shown in Fig. 1(a) for N=1. Mechanical impedance of ith layer is denoted by Z[i] (i =0 and i=2N+1
are also allocated outside the system), and the position of boundary between ith and (i+1)th layers isindicated by ξ[i], where ξ is a coordinate based on
propagation time of the wave. A transmitter for input and a receiver for output are located at ξ =λT
and ξ = λR, respectively.
In this study, the effect of a transmitter and receiver is interpreted as insertion of new layers, as

Fig. 1 (a) Transmitter and receiver located on a
2N-layered system (in the case of N=1). (b) Representation of transmitter and receiver.

Fig. 2 Some exceptional cases. (a) When λT = ξ[1].
(b) When λT = λR.

shown in Fig. 1(b), each of which has the propertyof spatial dipole delta function discussed in ref. 3(the polarity is depicted in the figure), and thelength of the inserted layer is given by(1)
d λ = d λ0 / ω
where dλ0 is a constant sufficiently smaller than the
wavelength of wave, and ω is an angular frequencyof wave. (The resolution is preserved for higher ωwith smaller wavelength. The situation of ω→0 is
not considered.) The layers are renumbered as Z1,
Z2, ... , Z2N + 4. In Fig. 1, Z1 = Z2 = Z3 = Z[1], and Z4 =
Z5 = Z6 = Z[2].
Some exceptional examples are shown in Fig. 2.
In Fig. 2(a), a transmitter is located on an original
boundary of layers, and a newly inserted layer isdivided into two parts with different mechanical
impedance. In Fig. 2(b), when a transmitter andreceiver are located on the same position, which isused for the calculation of driving-point frequency
response, the degeneration from 2N+4 layers to
2N+2 layers occurs.
In any case, the number of layers must be aneven number in this methodology. The transformation between layer numbers before and after theinsertion of new layers, as well as new layer numbers for transmitter (T) and receiver (R), should be
stored for the matrix construction below. In the caseof Fig. 2(a), that may be written as {[1]}⇔{1,2};{[2]}⇔{3,4,5,6}; {T}⇔{2,3}; {R}⇔{5}, where{ } denotes a mathematical set, or a mapping f as
f(1) = f(2) = [1], f(3) = … = f(6) = [2], and a mapping g as g(2) = g(3) = T, g(5) = R, are defined.
On the system with renumbered layers, threekinds of matrices, with two types, respectively, areconstructed, the behaviors of which are illustrated
in Fig. 3. D1 and D2 represent the propagation ofenergy mode η = (η1, η2, ..., η2N+4)t, considering theloss due to (irreversible) dissipation processes. S1and S2 represent the reflection and transmission of η
based on energy-conserving processes. K1 and K2
are devoted to the input and output processes. See
ref. 1 for details with regard to those matrices.
Using the data of mappings f and g and other information on the system, those matrices are constructed; for example, in the case of Fig. 1(b), they
have the following forms:
D1  D2  blkdiagd 1, , d 3, d 4, , d 6,(2)

where “blkdiag” is a function to construct a block
diagonal matrix from its arguments, and di and δ
are complex propagation factors on ith layer and on
transmitter or receiver, respectively, andS1 = blkdiag(Strans , S[1, 2 ] , Strans ),(3)
S 2 = blkdiag(− r[ 0,1] , S trans , S trans , r[ 2, 3] ),where⎛ 0 1⎞
S trans = ⎜⎜⎟⎟,⎝ 1 0⎠⎛ r[ i −1, i ]S[i −1, i ] = ⎜⎜ 1 − r2
[ i −1, i ]⎝1 − r[2i −1, i ] ⎞⎟,− r[i −1, i ] ⎟⎠r[ i −1, i ] = ( Z [i −1] − Z [i ] ) /( Z [i −1] + Z [i ] ),andK1 in = − K 2 in = blkdiag(0,+κ [1] , 0, 0, 0, 0) ,K1 out = − K 2 out = blkdiag(0, 0, 0, 0,−κ [ 2 ] , 0) ,(4)

where κ[i] is the square root of a kind of driving(and detecting) force on [i]-th layer. (Input andoutput processes are expressed with different matrices, since an input and an output are performedon different layers, when a spatial transfer response
is considered.)Using these matrices, the following Neumann series1) is calculated, leading to the spatial transfer
frequency response of the system in this study.
( j)(R ( j ) ) A0( j ) K in( j )η 0 ,η (ω ) = ∑ ∑ K out
16

j =1

∞

n

(5)

n =0

where η0 = (1,1,...,1)t, and A0(j), R(j), and (Kin(j), Kout(j))
for 16 probabilistic paths are listed in Table I.
References
1. M. Ohki: Jpn. J. Appl. Phys. 45 (2006) 4462.
2. M. Ohki: Jpn. J. Appl. Phys. 46 (2007) 4474.
3. M. Ohki and K. Toda: Jpn. J. Appl. Phys. 42 (2003)
3102.
Table I. 16 cases of probabilistic paths (j = 1--16).
R(j)(Kin(j), Kout(j))
j
A0(j)
1
D1
R1=D1S2D2S1(K1 in, K2 out)
2
D2
R2=D2S1D1S2(K2 in, K1 out)
3
S1D1
R3=S1D1S2D2(K1 in, K2 out)
4
S2D2
R4=S2D2S1D1(K2 in, K1 out)
5
D2S1
R2
(K2 in, K1 out)
6
D1S2
R1
(K1 in, K2 out)
7
S2D2S1R4(K2 in, K1 out)
8
S1D1S2R3(K1 in, K2 out)
9
D2S1D1R2(K1 in, K1 out)
10
D1S2D2R1(K2 in, K2 out)
11
R1R1
(K2 in, K2 out)
12R2R2
(K1 in, K1 out)
13
R3R3
(K2 in, K2 out)
14
R4R4
(K1 in, K1 out)
15
R3S1
R3
(K2 in, K2 out)
16
R4S2
R4
(K1 in, K1 out)

Fig. 3 Diagram of behaviors of matrices D1, D2, S1,
S2, K1 and K2 (in Fig. 1(b)).

1P4-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 99- 100
11-13 November, 2008

Characteristics of piezoelectric ceramic transducers
tapered with exponential function
Jungsoon Kim1‡, Moojoon Kim2, Kanglyeol Ha2(1Dept. of Multimedia Eng., Tongmyong Univ.; 2Dept. of Physics, Pukyong Univ.)

1. Introduction
In order to obtain wide frequency bandwidth,the ultrasonic transducers with tapered piezoelectric
ceramics have been studied[1~4]. An ultrasonicprobe for medical diagnosis was made of thearrayed piezoelectric elements with non-uniform
thickness because of high resolution and wideband
characteristics[5]. However, in these approaches,
the characteristic evaluation has reported on thespecific shape such as an arc or a type with linearlychanged thickness[4]. The studies which estimate
the performance of the transducer for each design
factors are not enough so far.
In this study, an exponential function to give
selective variation in thickness along the length ofthe piezoelectric ceramic was newly introduced.
The electro-mechanical characteristics weretheoretically analyzed for two transducers of which
thickness is changed exponentially according to thefunction. To confirm the efficacy of the analysis
method, some piezoelectric ceramic transducers
tapered in accordance with the exponential function
were fabricated, and the power transfer functions of
the transducers were investigated with experiment.
2. Theory
When the thickness of slander typerectangular piezoelectric vibrator is changed
exponentially along the length as shown in Fig. 1,
the thickness can be represented by the function of
the position x as following equation.
l (e gT − e gx ) + lmax (e gx − 1)(1)l ( x ) = mine gT − 1
Here, lmax and lmin are thickness at x=T and x=0,respectively. The parameter g is shape index. The
equation (1) has the following values for each
limitation of g.
(2a)
lim l ( x ) = lmaxg →−∞(l − l )lim l (x ) = max min x + l
g →0

lim l ( x ) = l min

T

g →∞

min

(2b)

lmax

l(x)=li

lmin

x
W

T

T/N

Fig. 1. Calculation model for piezoelectric vibrator
with exponentially tapered thickness.
given byjω
Y3 0,T = ∫

T

0

1+

kT2

ε 33S

W
, (3)
l (x )dx⎛ ωl (x ) ⎞Zj l − 2 tan⎜⎜ D ⎟⎟Z0
⎝ 2v33 ⎠⎛ ωl (x ) ⎞⎛ ωl ( x ) ⎞Z⎜⎜ D ⎟⎟ 1 − j l cot⎜⎜ D ⎟⎟Z0
⎝ v33 ⎠
⎝ v33 ⎠
where, ω: angular frequency, ε33S: dielectric
constant, W: width of the vibrator, kT: electromechanical coupling coefficient, v33D: soundvelocity of the piezoelectric vibrator, Z0:
characteristic impedance of the piezoelectric
vibrator, and dx = lim T N .
N →∞Using the Eq. (3), the power transfer function of thetransducer is given by
4 Rg Rm,(4)
H p (ω ) =2{Rg + Rm }2 + ⎧⎨ X m − 1 ⎫⎬
ωC 0 ⎭⎩
where Rg is internal resistance of the electric source
and the clamped impedance Z 0 0,T and the motional
impedance Z m 0,T are given as follows:
Z 0 0,T =

1
T

ε 33S

,

(5)

∫ jω l (x )W dx
0(2c)

To analyze the characteristics of the vibrator, we
assumed that the piezoelectric ceramic with length
T is divided by N. When the divide number N goesto infinite, the input admittance of the vibrator is-----------------------------------------------------------kimmj@pknu.ac.krz

Z m 0,T =3.

1− Z 0 0,T = Rm + jX m .
Y3 0,T(6)

Experiment and Results

Two transducers with exponentially tapered
thickness was obtained from a rectangularpiezoelectric bulk ceramic of 21.85(L)ｘ13.05(W)-50Transfer Function[dB]ｘ12.10(H) mm3 size by cutting as shown in Fig. 2.
The ceramic is uniformly polarized along z-axis.
A CNC(computer numerical control) millingmachine with CAD/CAM software was used in the
cutting process, and the very slow cutting progress
rate of 0.016mm/s in cooling water was taken toprevent depolarization due to the mechanical stressand heat during the process. The material constantsof the ceramic are shown in Table 1.

-40

-60

g=50
g=-50

-70

-80

-90

-100
500

1000

1500

2000

2500

3000

Frequency[kHz](a) Theory-40(a) g=50(b) g=-50

Transfer Function[dB]

-50

-60

g=50
g=-50

-70

-80

-90

Fig. 2. Photograph of piezoelectric vibrators withexponentially tapered thickness.

-100
500

1000

1500

2000

2500

3000

Frequency[kHz]Table 1. Material constants of the piezoelectric
vibrator.
Density [kg/m3]
7649.9
Electro-mechanical0.381
Coupling constant kTDielectric constant εS33/ε0839
DPhase velocity v 33 [m/s] 4116.3
The shape index and size of the vibrators shown in
Fig. 2 are listed in Table 2.
Table 2. Size and g-values of the fabricatedtransducers.
glmax[mm] lmin[mm] W[mm]
T[mm]
50
10.9
0.8
13.0
20.8
-50
9.9
1.0
13.0
19.2
The theoretical and experimental power transfer
functions which reveal the frequency bandwidthcharacteristics are shown in Fig. 3. The -3dB
bandwidth of the transducer of g=50 is about 68.4%
in the experimental result. In case of g=-50, though
the bandwidth is over than 118.4%, the peak oftransfer function is less 10 dB than the transducer of
g=50 in the given frequency range. The center
frequencies of the transducers of g=50 and g=-50
are 2319.3 kHz and 1709.0 kHz, respectively. The
tendency of frequency change with shape index g in
given frequency range is consistent with thetheoretical one.

(b) ExperimentFig. 3. Power transfer function change with vibrator
shape.
Acknowledgment
This work was supported by the Korea
Research Foundation Grant funded by the Korean
Government(MOEHRD,
Basic
Research
Promotion Fund) (KRF-2006-531-D0005).
References
1. Y. Tomikawa. A. Yamada. and M. Onoe, "WideBand Ultrasonic Transducer Using Tapered
Piezoelectric Ceramics for Non-Destructive
Inspection," Jpn. Jour. Appl. Phys., vol. 23, suppl.
23-1, pp. 113-115 (1984).
2. P. G. Barthe and P. J. Benkeser, “A Staircase
Model of Tapered-thickness Piezo-electric
Ceramics," J. Acoust. Soc. Amer., 89, pp. 14341442 (1991).
3. B. N. Alekseev, D. B. Dianov, and S.P. Karuzo,"Tapered-Bar Transducer," in Proceedings of theEighth All-Union Acoustics Conference [inRussian], Moscow, (1973).
4. D. Kim, J. Han, J. Yang, M. Kim, K. Ha,"Characteristic Evaluation for a PZT Transducer
with Cylindrical Rear Surface, " Journal of the
Acoustical Society of Korea, vol. 26, no. 1E, pp.
14-20 (2007).
5. A. M. Hanafy, "Broadband Phased Array
Transducer Design with Frequency-Controlled
Two-Dimensional Capability," SPIE 3341, pp.
64-82, (1998).

1P4-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 101- 102
11-13 November, 2008

Analysis of Q-value of Quartz Crystal Tuning Fork Using
Thermoelastic Coupling Equations
熱弾性方程式による音叉型水晶振動子のＱ値の解析
Hideaki Itoh and Yuhya Tamaki（Shinshu Univ. Dep. Electr & Elect. Eng）
伊藤秀明, 玉木悠也（信州大 電気電子工）

1. Introduction
Zener 1)2) investigated a damping coefficient andQ-value of a cantilever beam in bending vibrationby using thermoelastic coupling equations andderived a formula for the damping coefficient due tothermoelastic damping. To date, many researchers
3)4)5)
have been developing Zener’s works more
precisely.
The comparison between the measured
and the calculated value on the damping coefficientof cantilever beams has been made and the goodconsistency between them has been shown4).
In this study, we derived a formula for Q-valueof quartz crystal tuning fork theoretically by using
thermoelastic coupling equations given by Sieh4).
The comparison between the measured and thecalculated values of Q-value for etching processed
quartz crystal tuning fork is carried out.
2. Analysis and discussion
We pay attention to the transverse vibration of
one arm as cantilever beam, in order to obtain
Q-value of the quartz crystal tuning fork which
consists of two arms undergoing flexural vibrationeach other in opposite direction as shown in Fig.1.

temperature gradient occurs in the y direction of thearm according to compression-expansion behavior
and the thermal energy diffuses at the quartz crystal
surface by heat conduction. At last, the thermalenergy dissipates to the external environment fromthe surface.
In this study, we rearranged the thermoelatic
coupling equations given by Sieh4) and adopted therearranged equations described as
h
∂ 4v
∂ 2v
∂ 2θ
2
+
ρ
bh
+
E
α
b
y
∫− h 2 ∂x 2 dy = 0,
∂x 4
∂t 2
⎛ ∂ 2θ ∂ 2θ ⎞∂θ⎟ − ρc E
k ⎜⎜ 2 +
2 ⎟
∂t
∂
x
∂
y
⎝
⎠

(1)

EI

+ EαT0 y

2(2)

E α T0 2 ∂θ∂ v−
dy = 0 ,h ∫− h 2 ∂ t∂x 2 ∂t3hwhere E, I, α, θ, k, T0, cE, ρ are Young modulus,
moment of inertia, thermal expansion coefficient,temperature change from absolute room temperature,
thermal conductivity, absolute room temperature,heat capacity, and density of the beam, respectively.
When we solve eqs.(1) and (2), the boundary
conditions are applied to the arm shown in Fig.1 asfollows: (a) the boundary conditions of the arm are
fixed at x=0 and expressed by∂v(3),v ( x, t ) = ( x, t ) = 0∂x(b) the boundary conditions of the arm are free at
x=l and expressed byh∂ 2v+ Eαb ∫ h2 yθ ( x, y, t )dy = 0 and
2
−
∂x
2
h
∂ 3v
∂θ
(4),
EI 3 + Eαb ∫ h2 y (x, y, t )dy = 0

EI∂x

Fig.1 Configuration of Quartz Crystal Tuning Fork

The deflection displacement of the right arm in the y
direction, thickness, length, and width of the arm areshown as v(x,t), b, l, and h in Fig.1. Time and thecoordinate of longitudinal direction of the arm is set
to be t and x, respectively.
When the quartz
crystal tuning fork undergoes in flexural vibration,
temperature at compressing side of the arm
increases because of adiabatic thermal compression
and at lengthening side decreases because of
adiabatic thermal expansion.
Therefore,-----------------------------------------------------------E-mail: rokuro1@gipwc.shinshu-u.ac.jp

−

2

∂x

(c) the adiabatic thermal boundary conditions of
the arm are described as∂θh∂θ= 0 at x = 0 , l and= 0 at y = ± (5),
∂x

∂y

2

(d) the isothermal boundary conditions of the arm
are described asθ = 0 at x = 0, l and y = ±

h
2

(6).

Using the definition of Q-value5) given by
Q −1 = 2

Im(ω )
Re(ω )(7),

we can derive Q-value formula using complex
angular frequency ω which is determined by theeigenvalue equation obtained by substituting theboundary conditions eqs.(3)～(6) into eqs.(1) and(2)6).

becomes a calculated CI value based on thevibration leakage.
50

1.0E+06

40

C I value[kΩ ]1.0E+05

Q value

1.0E+04

measured value

1.0E+03

caluculated value(adiabatic
boundary condition)
calculated value(isothermalboundary condition)

1.0E+02

1.0E+0130

CI value(measured)20

CI value due to thermoelastic
damping(calculated)

10

CI value due to vibrationalleak(calculated)

0-50

1.0E+00
0.098

0.1

0.102

0.104

0.106

0.108

0.11

0.112

0.114

0.116

h/l
Fig.2 Comparison between calculated and measured Q
value as a function of the parameter h/l

Figure 2 shows the comparison between
calculated and measured Q-value as a function of
the parameter h/l.
As shown in Fig.2, themeasured value is very close to the calculated value
using adiabatic approximation. Therefore, Q-valueof quartz crystal tuning fork can be calculated byusing a formula for Q-value obtained underadiabatic boundary condition. Furthermore, thedifference between the calculated Q-value based on
the thermoelasticity and the measured Q-value is
responsible for the effect of both heat conduction to
the length direction and vibration leakage from thebase.
Figure 3 show a temperature-CI value
characteristics7) for an etching processed quartz
crystal tuning fork. As shown in Fig. 3, thetemperature-CI
valuecharacteristicsshows
V-shaped curve becoming a bottom at about 20℃.
Linear increase response in CI value with risingtemperature is based on the thermoelasticity because
the reciprocal of Q-value formula is proportional toabsolute temperature5). On the other hand, linear
decrease response in CI value with risingtemperature seems to be based on the vibration
leakage.
In Fig.3, the whole CI value wasestimated to be 39.0kΩ at 25℃.
From the data of
Fig.3, we can estimate CI value based on thethermoelasticity at 25 ℃ , by the least squares
method applied to experimental data over 25℃, tobe 37.0kΩ which is about 95% of the whole CI
value at 25℃. By omitting the effect of heat
conduction to the length direction, the remainder
subtracted the calculated CI value based on thethermoelasticity from the measured CI value

-25

0

25

50

75

100

Temperature[℃]
Fig.3 Temperature-CI value characteristics

We calculated the remainder to be 2kΩ, which
was about 5% of the whole CI value and was CI
value based on the vibration leakage from the baseto the holder at 25℃.
3. Conclusion
We could derive a formula for Q-value of aquartz crystal tuning fork by using the thermelastic
coupling equations for a cantilever beam from theviewpoint of the thermoelasticity. As a result of
calculating Q-value under both adiabatic andisothermal boundary conditions, it was clear that thecalculated value under adiabatic boundary condition
was more close to the measured value on Q-value ofan etching processed quartz crystal tuning fork thanthat under isothermal boundary condition. It is
concluded that the phenomenon that CI value
increases with rising temperature in hightemperature region is due to the effect of thethermoelasticity and that CI value decreases withrising temperature in low temperature region is dueto the effect of the vibration leakage from the baseof a quartz crystal tuning fork to the holder.
References
1. C.Zener, Phys. Rev. 52, 230 (1937).
2. C.Zener, Phys. Rev. 53, 90 (1938).
3.L.D.Landau and E.M.Lifshitz, Theory of Elasticity(Pergamon Press, Oxford, 1959).
4. R.C.Shieh, J. Appl. Mech. 38, 839 (1971).
5. R.Lifshitz and M.L.Roukes, Phys. Rev. B 61,
5600 (2000).
6. H. Itoh et. al., Proc. 36th EM Symp., (2007) p.5.
7. O.Kawauchi et. al., Proc. 32th EM Symp., (2003)
p.39.

1P4-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 103- 104
11-13 November, 2008

Analytical Study on Load Effects of LiNbO3 Vibrator
for Ultrasonic Motor Using Vibration Mode Coupling
LiNbO3結合モード利用モータ振動子の負荷影響に関する解析的検討
Kyousuke Shibata‡, Hideki Tamura*, Manabu Aoyagi1, Takehiro Takano2,
Yoshiro Tomikawa and Seiji Hirose(Yamagata Univ., 1Muroran Inst. of Tech., 2Tohoku Inst. of Tech.)柴田恭佑‡，田村英樹*，青柳学1，高野剛浩2，富川義朗，広瀬精二（山形大・工、1室蘭工大、2東北工大）

1. Introduction

LiNbO 3 vibrator(10x2.55x0.5mm, Φ = 14°)with Cr+Au evaporated electrodekz
contact
point

uV

u

fixed

2. FEM analysis with the spring element to load
Figure.1 illustrate an experimental constructionof stator. The center points on the top and bottom
surfaces of the LiNbO3 rectabgular vibrator are
fixed for support and are used for electric power
feed. The vibrator is based on the 135 o X-rotated
Y-plate, length L, width W and thickness t=0.5 mm,
and applied second rotation Φ in the y'-axis asshown in Fig. 1(b) .
We had analyzed the vibrator by FEM method
using the simple rectangular crystal model. In thisstudy, we try to apply an influence of loads for the
analysis model, and it is assumed that a mechanicalspring which is attached at the contact point of thevibrator acts the load by its reaction force.
Therefore, the springs of the vertical and horizontal------------------------------------------------------------*E-mail : htamura@yz.yamagata-u.ac.jp

Resonance frequency f0 (kHz)H
The authors have investigated ultrasonic motorskx1-4) Contact point
using the piezoelectric single-crystal LiNbO3.
One of them, we proposed the single phase drivingz'Φ
motor using the coupling-mode combined with aLxlongitudinal and flexural in-plane modes in ay'rectangular plate. An additional rotated X-rotatedW
Y-cut rectangular plate can provide theThickness : t = 0.5 mm
Phosphor-bronze plate
coupling-modes caused by the crystal anisotropy.
(thickness 0.2mm)
x-rotation : θ = 135 deg
Rotational direction of the single phase motor can(a) Support configuration of (b) Parameters of vibrator
be reversed by switching the two modes. To obtainstator vibrator for a trial.
and applied spring loads.
the same characteristics between the both rotation,
Fig.1 Stator vibrator of an ultrasonic motor using
we designed the vibrational displacements of both
3)
vibration mode coupling in LiNbO3
modes to be equal by FEM analysis. However,rectangular vibrator.
experimental results showed large difference of therevolution characteristics between the both
333
W/L=0.255
direction. Because the generative force of the326 Φ=14 deg
LiNbO3 is small, and the vibrator easily takes thekz
319 Upper-mode
influence of the preload and external load. The
kx
312
condition of modes are changed by the loads fromkz and kx
the designed it. This paper shows the analytical305
investigation for the influence of the loads using a298
FEM model with spring elements.
Lower-mode
291

284

0

2
4
6
8
constant of spring k ×10 7 (N/m)

10

Fig.2 Analysis result of the resonance frequency
correlated with spring constant k of loads.

(a) Upper (b) Lower (c) Upper (d) Lower
no loadFig.3

kx,kz = 4×106(N/m)(e) Upper(f) Lower

kx,kz = 6×107(N/m)

Load influence of the vibration resonancemode.(W/L=0.255)

3. Conclusions
Our previous designed stator vibrator using thecoupling-mode has problems in experimental
characteristics. In this study, the load influence forthe vibrator is considered in the FEM analysis using
a simple spring element, and we provide theanalytical results that the single crystal vibrator islarge affected by the external loads and the previous

Resonance frequency f0 (kHz)no loadkz and kx= 4×106(N/m)
kz and kx= 6×107(N/m)
340
330
320
310
300
290
280
270
260

Φ=14 deg

0.22

Fig.4

0.23

0.24

0.25
W/L

0.26

0.27

0.28

Resonance frequency correlated with thewidth-to-length ratio W/L depended on theload of springs.

no loadkz and kx= 4×106(N/m)
kz and kx= 6×107(N/m)

Displacement ratio uH / uV

components are applied using "COMBIN14"
element of ANSYS as shown in Fig. 1(b), and thespring constants are kz and kx, respectively. The
another side of the springs is fixed.
Two coupling-modes are caused by the originatedlongitudinal 1st and flexural 2nd modes. The
coupling mode with the higher resonance frequency
is called the upper mode, and the another is called
the lower mode. The resonance frequencies of thecoupling-modes are changed by strength of thesprings as shown in Fig.2. The frequencies increase
with the strength of springs, and its tendency
accords with the experimental experience. The load
influence not only changes the resonant frequency
but also deforms of each mode as shown in Fig.3.
These influences are one of the reasons of the large
difference of the motor characteristics between theboth rotation directions.
We require the conditions of the displacement at
the contact point for the vibrator design as follows:(a) the upper and lower modes have to same
displacement ratio uH/uV,(b) and the vertical and horizontal components
have to be equal each other (uH/uV =1).
The vibrator designed on no-load fulfills above
conditions as shown in Fig.3(a) and (b). However,the loaded vibrator shown in Fig. 3(e) to 3(f)distinctly deviates from the request. The analysis
results for the load influence of the resonancefrequencies and displacement ratio uH/uV correlatedwith the width-to-length ratio W/L are shown in Fig.
4 and 5, respectively. The both characteristics are
shifted by load; therefore, determinate value of W/L=0.255 when Φ =14 o is not suitable under theloading. For example, when the loaded spring
constants kz and kx equal 4x106 N/m, the both
displacement ratios of the upper and lower modes
are on the same at W/L =0.244. However, its
displacement ratio uH/uV is about 1.55 and notequals one; therefore, it is necessary to design thesuitable width-to-length ratio and crystal cut-angle
with the load influence.
Additionally, in case of the large loading, forinstance when kz and kx equal 6x107 N/m, thedisplacement ratios between the upper and lower
modes are not crossing any more. Thus, a loading
limit will be able to be estimated by this method.

100

Φ=14 deg
Fig.4(e)10(c)(a),(b)1(uV = uH)

(d)
(f)

0.1
0.22

Fig.5

0.23

0.24

0.25 0.26
W/L

0.27

0.28

Displacement ratio at the contact point
correlated with width-to-length ratio W/Ldepended on the load of springs.

dimensions of vibrator are not suitable for an actual
condition in loading.
For future work, the correlation between thevalues of spring constant as the load and the actualload force have to be clear, and it is necessary toestablish the design method of the vibrator
corresponding to the applied load.
Acknowledgment
This research was partially supported by the Ministry of
Education, Culture, Sports, Science and Technology,
Grantin-Aid for Scientific Research on Priority Areas(No.438)No.19016001.

References(1) T. Takano et. al., Proc. 10th Int. Conf. Actuators 2006,
pp.453-456, 2006.
(2) H. Tamura et. al., Jpn. J. Appl. Phys. Vol. 46, 7B
pp.4698-4703, 2007
(3) H. Tamura et. al., Jpn. J. Appl. Phys. Vol. 47, No.5
pp.4015-4020, 2008
(4) H. Tamura et. al., Jpn. J. Appl. Phys. Vol. 47, No.5
pp.4034-4040, 2008

1P4-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 105- 106
11-13 November, 2008

A Study on the Shape of Longitudinal Bar Resonators
used as Piezoelectric Vibratory Tactile Sensors
圧電振動型触覚センサの振動子形状の検討
Subaru Kudo (Ishinomaki Senshu Univ.)
工藤すばる（石巻専修大 理工）

1. Introduction
Various piezoelectric vibratory tactile sensors
have been proposed for measuring the softness andhardness of an object 1-7). These tactile sensors
utilize the longitudinal-mode, flexural-mode oredge-mode vibration of the resonators. They makeuse of changes in the resonance frequencies of theresonators, which are induced when their vibrating
sections are brought into contact with an object. In
these tactile sensors, the longitudinal bar typesensor has been the most studied 1,4,7), and thesensitivity of the resonance frequency change on
the tactile sensor was investigated using the
distributed constant-circuit model of theresonator 8).
In this study, the shape of the longitudinal bar
resonator is considered for improving the sensitivity
on the piezoelectric vibratory tactile sensor. First,
the approximate equation of the frequency changeof the tactile sensor in case of contacting with asofter object is derived. The experimental results ofsensitivities for the tactile sensor are discussed fromthe viewpoint of the mass of the resonator. Then,the equivalent masses of the horn type resonators
are calculated using the finite element method.
2. Sensitivity of tactile sensor
Figure 1 shows theconstruction of tactile
sensor with a longitudinalbar resonator. When thetactile sensor, which isdriven in the longitudinalmode, touches an object,
the softness and hardnessof the object are detected
as changes in resonancefrequencies.
In general, theresonance angular Fig.1 Construction of tactile sensor
with longitudinal bar resonator.
frequency ω0 of-------------------------------------------------------------kudou@isenshu-u.ac.jp

a resonator is shown by ω20＝s/ｍ0. Here, m0 and s
are the equivalent mass and stiffness of theresonator, respectively. When the resonator iscontacted with a softer object, the resonant
frequency changes by an additional mass effect. In
this case, the resonance angular frequency ω isapproximately given by ω2＝s/(ｍ0+ｍe), where meis an additional mass. Then, the resonancefrequency change is expressed by−1fme ⎞ 2 .
⎛= ⎜1 +
⎟
f0 ⎝
m0 ⎠

(1)

Moreover, in the case of assuming that 1≫me/m0,
the sensitivity of the frequency change ratio isexpressed as
me
me
Δf
(2)
≅−
=−
f0
2m 0
2δ M 0, where Δf=f-f0 andδ(=m0/M0 ; M0:total mass) isthe equivalent mass coefficient.
This approximate equation means that thesensitivity of tactile sensor is inversely proportional
to the equivalent mass of the resonator. Then, theresonator with smallδis suitable for increasing thesensitivity.
Figure 2 shows the experimental results for thetactile sensor with the longitudinal bar resonator,
where Lc=50mm and resonance frequency
f0=51.55kHz. When the load added to test pieces
increased, the resonance frequencies of theresonator gradually decreased. The amount ofdecrease of resonance frequency is expressed as
Δf (=fL-f0), where fL is the resonance frequency
when a load is applied and f0 is the resonancefrequency with no load. The characteristics between
the load and Δf show the tendency that the amountof decrease for the soft test piece S1 is larger thanthe hard test pieces S2 and S3. Figure 3 shows therelationship between the frequency change ratio|Δf/f0| at load W=4gf and the mass M0 of theresonator. It is clear that the sensitivity of |Δf/f0| isinversely proportional to the mass of the resonator
as shown by eq.(2). The relationship between|Δf/f0| and M0 is estimated to be |Δf/f0|∝M0–0.799
by curve fitting.

become small when LA ≒ 6mm. From thesecalculated results, it became clear that there is apossibility to improve sensitivity by designing theshape of the longitudinal bar resonator.

0-10

Δf (Hz)

-20

0.5

-30
-40

equivalent mass m0 (g)

e
g
n
a
h
c
y
c
n
e
u
q
e
r
f
e
c
n
a
n
o
s
e
r

S1 (E=0.04M Pa)
S2 (E=0.06M Pa)
S3 (E=0.15M Pa)

-50
-60
-1

0

1

2

3

4

5

6

7

8

9

10

11

L oad W (gf)Fig.2 Characteristics of longitudinal-bar type tactile
sensor. (Lc=50mm, f0=51.55kHz, first mode)
0.9

0.4
0.3
0.2
0.1

W1=4mm , Lc=16mm , t=2mm

0.0

0.8

4

6

0.7

δ

0.5
0.4

0.2
0.1

10

12

Fig.5 Calculated relationship between LA and m0.

composite type
PZT type

0.6

0.3

8
LA (mm)W=4 gftest piece: S1
first mode

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Mass M (g)0
Fig.3. Experimental relationships
between |Δf/f0|
and Mass.

3. Calculated results of the equivalent mass
To consider theeffect on a shape ofthe bar resonator,
the equivalentmasses of the horn
type resonators in
Fig.4 are calculatedusing the finite
element method.
Table I shows thecalculated results of Fig.4 Horn type longitudinal
the equivalent mass
bar resonator.
of the resonator in
Fig.4(a). It is clarified that the equivalent mass m0
and the equivalent mass coefficientδare small as
the width W2 of the sensor tip becomes smaller. On
the other hand, Figs. 4 and 5 show the calculated
results of the equivalent mass and the eqivalentmass coefficent in Fig.4(b). The values of m0 andδ
Table I. Calculated results of equivalent mass.
(Lc=16mm, W1=4mm, t=2mm,ρ=7900kg/m3)
W2 (mm)4.0
2.0
1.0
Equivalent mass m0 (g)0.494 0.262 0.158
Total mass M0 (g)1.011 0.758 0.632
0.49 0.35 0.25
Equivalent mass coefficientδ

equivalent mass coefficient|Δf/f0| (%)

e
g
n
a
h
c
y
c
n
e
u
q
e
r
f
e
c
n
a
n
o
s
e
r

W2=3mm
W2=2mm
W2=1mm

0.5

W2=3mm
W2=2mm
W2=1mm

0.4

0.3

0.2

0.1

W1=4mm , Lc=16mm , t=2mm
468
LA (mm)10

12

Fig.6 Calculated relationship between LA andδ.
4. Conclusion
The shape of the longitudinal bar resonator wasstudied for improving the sensitivity on thepiezoelectric vibratory tactile sensor. This work waspartially supported by a Grant-in-Aid for Scientific
Research C2(No.19560426) from the Japan Society
for the Promotion of Science, and a Grant from
Ishinomaki Senshu University.
References
1. S.Omata and Y.Terumura:Sensors and Actuators
A, 35(1992) 9.
2. M.Maesawa, et al : Proc.1997 Int. Cof.
Solid-State Sen. & Actu. (1997) 117.
3. H.Itoh, et al : Jpn.J.Appl.Phys 38 (1999) 3225.
4. Y.Murayama and S.Omata:IEEE Trans. Ultra.
Fero. & Freq. Cont.(2005)434.
5. S.Kudo : Jpn.J.Appl.Phys 44 (2005) 4501.
6. H.Watanabe : Jpn.J.Appl.Phys 40 (2001) 3704.
7. C.Kleesattel and G.M.L.Gladwell:
ULTRASONICS (1968)175.
8. S.Kudo : Jpn.J.Appl.Phys 46 (2007) 4704.

1P4-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 107- 108
11-13 November, 2008

AStudy on Sensitivity of Frequency-Change-Type Force Sensor
周波数変化型力センサの感度に関する研究
Sumio Sugawara, Masaki Yamakawa†, Subaru Kudo (Ishinomaki Senshu Univ.)†

菅原澄夫，山川将貴 ，工藤すばる（石巻専修大 理工）

1. Introduction
A high-sensitivity frequency-change-typeforce sensor has been required for application to theattitude control and navigation systems of moving
objects such as vehicles. As such a sensor, somestructures have been proposed.1) However, because
the change of the resonance frequency by axial
force is very small, these structures are unsuitable
for the required specification. Therefore, the authors
have proposed the force sensor utilizing an
out-of-plane mode to realize high sensitivity2). The
acceleration sensor3)-5) and the inclination angle
sensor6) can be also realized using this sensor.
In this paper, some frequency-change-typeforce sensors are designed using the finite-element
method. The sensor sensitivity is analyzed andcompared.
2. Structures of force sensor
Fig. 1 shows some force sensors utilizing thephenomenon that the resonance frequency of abending vibrator changes by axial force. Fig. 1(a) is
the structure utilizing an out-of-plane mode2). As
shown in Fig. 2(a), the sensor vibrates along thedirection which is vertical to its surface. On theother hand, Figs. 1(b) and 1(c) are the structuresutilizing an in-plane mode. The sensors vibrate
along the direction which is horizontal to its surface,
as shown in Figs. 2(b) and 2(c). Figs. 1(d) and 1(e)are the structures which are utilizing an in-planemode that two arms vibrate symmetrically, as
shown in Figs. 2(d) and 2(e).

(a) Type (a)(b) Type (b)Fig. 1(b) Type (b) (c) Type (c) (d) Type (d) (e) Type (e)Fig. 2Vibration modes of force sensor.

3. Analysis of Sensor Characteristics
The sensor material is stainless steel(SUS304), and the dimensions in Figs. 3(a) and3(b) are listed in Table Ⅰ. Ansys 11.0 is used assoftware for the finite-element analysis. The
displacements at the both ends of the sensor are
decreased, and the frequency change rate of Δf/f0 isanalyzed using the finite-element method when theaxial force along the y axis is applied to the sensor.
3.1 Displacements at base end
To support the sensor, the displacements at
both ends of the sensor must be decreased bychanging the shape of the base part. The analyzed
results of the displacements ui(i=x, y, z) at the baseend are shown as the ratio ui/ui0 to the maximum
displacement ui0 at the central part of the arm. The
A is B.

(c) Type (c)(d) Type (d)(e) Type (e)Structures of frequency-change-type force sensor.

-----------------------------------------------------------E-mail address: ssumio@isenshu-u.ac.jp(a) Type (a)value of ui/ui0 must be made less than 10-3. The
calculated values of ui/ui0 are listed in Table Ⅱ,

wｇ

Δℓb

w
wｇ

ℓb

Δf/f0 in the case of F=1N, that is, the sensor
sensitivity is also listed in Table Ⅱ. The sensors oftypes, (c), (a) and (e), are the high-sensitivity
structures.
f/f0 (ppm/N)and very small in the case of the sensors of types (a)and (e). The ratios at the base center are different
from the ratios at the base edge generally.

ℓb

ℓa

20

×10 3

Type (c)
(a)
(e)

10

Δ

wa

ℓｃ ℓ

-1.0

wa

wa

0
0.0

-0.5

ℓ

ℓc

(b)
(d)
0.5

1.0

F (N)

-10
-20

ℓa

Fig. 4 Calculated characteristics of F–Δf/f0
of force sensor.

ｙ

wｃ

ℓb

Δwｂ

ℓb
ｔ

w

(a) Types (a)～(c)Fig. 3
Table Ⅰ(b) Types (d) and (e)Symbols for dimensions.
Dimensions of sensor (mm).

(a) Types (a)～(c)
ℓ
ℓａ
ℓb
ℓc
Δℓb
w
wa
wc
wg
Δwb
t

ｚ

t

ｘ

30～38
8.0, 8.5
3.0～7.424
1.5～1.9
1.6, 7.6
0.2, 2.0
0.2, 2.0
0.5, 0.8
0.45, 2.4
0.2, 2.0(b) Types (d) and (e)
ℓ
ℓａ
ℓb
ℓc
Δℓb
w
wa
wc
wg
Δwb
t

32, 36
4.0, 6.0
24
2.0, 3.0
0.9, 4.8
0.2, 2.0

References

3.2 Sensitivity of sensor
When the force F along the y axis wasapplied to the sensor, and the change Δf of theresonance frequency of the sensor was analyzed.
Fig. 4 shows a relationship between F and Δf/f0.
Here, f0 is the resonance frequency. The change rate
Δf/f0 in the seep.
Resonance frequency
TypeSensitivity

The sensitivity of the frequency-change-typeforce sensor was analyzed using the finite-element
method. The sensors of types, (c), (a) and (e), arethe high-sensitivity structures and the displacement
ratios at both ends of types (a) and (e) are less than
10-3. As a result, the sensors of types (a) and (e) canbe used because of high-sensitivity and small
displacements. From the standpoint of realizing a
MEMS sensor, the sensor of type (a) is preferable.
Acknowledgments
The work was partially supported by aGrant-in-Aid for Scientific Research (No.
19560047) from the Ministry of Education, Culture,
Sports, Science, and Technology, Japan.

0.5, 0.8
00.2, 2.0

Table Ⅱ

4．Conclusions

1) L. Weisbond: US Patent 4,479,385 (1984).
2) S. Sugawara, et al.: Jpn. J. Appl. Phys., 41 (2002)
3433.
3) J. Takahashi, et al.: Jpn. J. Appl. Phys., 42 (2003)
3124.
4) J. Takahashi, et al.: Jpn. J. Appl. Phys., 43 (2004)
3035.
5) S. Sugawara, et al.: Jpn. J. Appl. Phys., 46 (2007)
4652.
6) S. Sugawara, et al.: Jpn. J. Appl. Phys., 47 (2008)
4048.

Calculated characteristics of force sensor.

Displacement ratio at base center

Displacement ratio at base edgeΔf/f（ppm/N) ux/ux0×10-3 uy/ux0×10-3 uz/ux0×10-3 ux/ux0×10-3

uy/ux0×10-3 uz/ux0×10-3

f0(Hz)Δｆ（Hz/N）

(a)

1,707

29.4

17,22300-0.34400-0.704(b)

14,997

4.2

279

0.884

0

0

0.884

8.392

0

(c)

1,870

37.7

20,194

0.039

0

0

0.039

4.744

0

(d)

14,481

2.5

172

0

-6.8250

0.346-6.825

0

(e)

1,789

23.8

13,2800-0.21800-0.2180

1P4-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 109- 110
11-13 November, 2008

Characterization of Electrical Probe for Measuring Induced
Charge on Surface of Piezoelectric Vibrator
圧電振動子表面誘起電荷測定用探針の量的評価
Shigetaka Kaga1† and Morio Onoe2(1Nihon Denpa Kogyo Co. Ltd.; 2Professor Emeritus, University of Tokyo)
加賀重隆 1†，尾上守夫 2

1.

（1 日本電波工業株式会社；

2

東京大学名誉教授）

Introduction

Electrical probe method developed by
Fukuyo is an excellent tool to identify various
vibration modes of a piezoelectric vibrator. 1, 2)
Piezoelectrically induced charge of a mode ispicked up by a small needle probe embeded in thelower electrode as shown in Fig. 1. Mechanicalscanning of the vibrator by an X-Y stage allowed toobtain a distribution of induced charge over thesurface. Fukuyo measured only the amplitude ofinduced charge. Watanabe, et al. 3, 4) introduced a
network analyzer, which allowed the measurementof phase as well as amplitude and the scanning of
frequency. Their works, however, were limited toqualitative observation of distribution pattern.
This paper presents more quantitative
characterization of a probe. Impedance of a probe is
kept as low as possible, so that the probe isaccounted to be a part of grounded lower electrodewith litttle disturbance of surrounding electricalfield. Hence the input to the network analyzer isessentially proportional to the current flowing theprobe. It consists of a desired piezoelectricallyinduced part and an undesired part caused mainly
by stray capacitances. The latter has to be
subtracted from the observed value. On a circle
diagram (vector) plot as a function of frequency, theformer part at a resonance is essentially a circle,
whereas the latter part is essentially constant, which
we call here "reference origin". The reference origin
is a slow varying function of frequency. Watanabe,
et al. determined a reference orgin at eachresonance in the following manner. First scan thefrequency in a wide range, second remove parts ofobserved values corresponding to resonannces,
third approximate remaining values by apolynomial function of frequency and finallycalculte an estimated value of reference origin at aparticular resonant frequency. 4)
The present paper shows that a reference
origin can be directly determined from observed-----------------------------------------------------------e-mail:1kagas@ndk.com;

2

m.onoe@ieee.org

values obtained by a frequency scanning in anarrow range around a resonance itself.
A probe picks up surface charge not only at
an infinitesimal point but also at surrounding points
due to fringing in electrical field. Its characteristics
can be exptressed by a spatial point spread function
similar to an optical point spread function of a lens.
Spacial distribution of surface charge of a main
thickness-shear mode usually contains components
of high spacial frequency due to effects of highovertones of contour modes. A spread function
reduces the observed amplitude of these highspacial frequency components.
In previous papers, distributions of surface
charge were analytically obtained and compairedwith experiments. A good agreement between
analyses and experiments was obtained, when aspread function is taking into an account. 5, 6, 7)This paper presents relationships between a
spread function and geometrical configurations of aprobe.
2.

Estimation of reference origin

Movements of a mechanical stage is slow intime. Hence a frequency scanning in a narrow range
can be completed at each point of mechanicalscanning with no extra time. This allows to draw
circle diagrams of several spurious modes with only
one mechanical scan. The use of circle diagrams
allows a sensitive detection of any irregularity
during mechanical scanFig. 1 Probe system to pick up induced chargeSince reference origin is essentially constantduring a narrow frequecy scanning, it contributes
only to DC componet in Fourier domain. Hence a
desired piezoelectrically induced part of a circle
diagram can be obtained as follows: first apply
Fourier trasform (FT) to circle diagram, second
remove DC component and third apply inverse FT.
Fig. 2 shows an experimental plot of circle
diagrams of the main (1,1,0) mode of an AT-cut
vibrator (x: 22.0 mm, y': 0.552 mm, z': 27.0 mm).
The vertical axis is distance in mechanical scanalong the x axis. Only a few circle digagrams areshown here in order to avoid congestion. It can beseen that their reference origins coincide with eachother. In terms of DC component of FT, standard
deiation of their spread is 1 %.

3.

Point spread function

References
1. H. Fukuyo: Bull. Tokyo Inst. Tech., series A(1955) no. 1.
2. I. Koga and H. Fukuyo: Jour. Inst. Comm. Eng.
36 (1953) 59. (in Japanese)
3. Ya. Watanabe, et al.: Proc. Ultrasonics Symp.,(1993) 571.
4. Ya. Watanabe, et al.: Trans. Inst. Comm. Eng.
J77-A, (1994) 285. (in Japanese)
5. R. D. Miundlin：Quart. Appl. Math. 19 (1961) 51.
6. R. D. Miundlin and D. C. Gazis: 4 th US Nat.
Congress Appl, Mech. (1962) 305.
7. M.Onoe and S. Kaga: Proc. Frequency Control
Symp. (2008) .
8. Yo. Watanabe: Ricoh Co. Ltd., private
communication.

Point spread functions are experimentally
evaluated for several combinations of the diameterof needle, the diameter of embedding hole and gap
between the surface of a vibrator and needle point.

Fig. 3 is an example showing theamplitude ratio between the main component
and a high spatial frequency component as afunction of the diameter of embedding hole.
The diameter of needle is kept to be a constantof 0.3 mm. The larger the hole diameter, thebroader the point spread function. Experimental
observations agree with FEM analysis ofelectrostatic field around the probe by Dr. Y.
Watanabe of Ricoh. 8)
Fig. 2 Circle diagrams of the main mode.
4.

Conclusion

Characteristics of electrical probe formeasuring piezoelectrically induced charge on thesurface of a vibrator quantitatively evaluated.
First a new method to estimate reference
origin of circle diagram is presented.
Second effects of geometrical configurationof a probe on its point spread function are
discussed.

Acknowledgment
The authors thank Mr. Okazaki of Nihon
Dempa Kogyo Co. for his constant support andencouragement and Dr. Y. Watanabe of Ricoh Co.,for his FEM analysis of electrostatic field aroundthe probe.

Fig. 3 Effect of hole diameteron point spread function

1P4-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 111- 112
11-13 November, 2008

Pure-shear mode BAW resonator consisting of(1120) textured AlN films(1120)配向 AlN 薄膜を用いた純横波モード共振子
Takahiko Yanagitani 1† and Masato Kiuchi 2 (1 Nagoya Institute of Technology,2
National Institute of Advanced Industrial Science and Technology)

柳谷隆彦 1‡，木内正人 2 (1 名古屋工業大学; 2 産業技術総合研究所）

1. Introduction

2. AlN film deposition(0001) textured hexagonal films such as ZnO
and AlN films have been widely used for
longitudinal wave or Rayleigh wave modepiezoelectric devices. We have previously shownthat (112 0) textured ZnO films can be formed
using various ion beam asisted deposition
technique 1-3). This film can be used forpure-shear mode FBAR 4) or SH-SAW devices 5).
On the other hand, (11 2 0) textured AlN films
have a number of potential advantages comparedto the ZnO films:

As shown in Fig.1, ion beam sputtering
deposition system with single ion gun was used
for AlN film deposition. This ion gun plays tworoles, sputtering nitrided Al metal target andbombarding the substrate surface. Nitrogen ion
beam with 3 keV was irradiated normal to thetarget surface and parallel to the substrate surface
simultaneously during the deposition. A gas
pressure of 0.02 Pa , and a nitrogen gas flow of
10 ccm were set during the deposition. AlN films
were deposited on the two types of substrates:
silica glass substrate (sample A) and Al electrodefilm/silica glass structured substrate (sample B).
Substrate temperatures during the deposition ofsample A and B were around 160 ºC and 340 ºC,
respectively.

- High chemical stability and resistance.
This is important for sensor application- Low intrinsic mechanical loss.
This result in high Q resonator.
- Low temperature coefficient of elastic
constant.
- High electrical breakdown strength, Highpower operation.
- High heat conductivty.
This realize high power operation.
- High acoustic velocity, High frequency
operation
Takada et al. have reported that H2 gas
introduction during deposition induces (11 2 0)
texture formation in a RF magnetron sputtering 6).
However, in-plane crystalline orientation, whichis essential for shear wave excitation, have notbeen achieved. From our previous study on the
ZnO film, it is known that ion bombardment
during deposion induces preferential (11 2 0) or(101 0) texture formation. This is caused by an
crystalline anisotropy of sputtering yield(difference of damage tolerance for ion
bombardment among crystal planes) 2). We
considered that the same holds for AlN whichhave same wurtzite structure as ZnO. In thisstudy, we then tried to fabricate (11 2 0) AlN filmusing ion beam sputtering technique 3).
Crystalline
orientation
andpiezoelectric
properties of the film have been also reported.

----------------------------------------------------------yana@nitech.ac.jp

Ion bombardment
50
Substrate

40

AlN film

Nitrogen ion beam

ECR
80
ion gunAl
targetSputteredparticles

3 kV
140

Fig. 1

Ion beam sputtering deposition systemwith single ion gun.

3. Crystalline orientation
Figure. 2 show the XRD patterns of the sample
A and B. (101 0) and (112 0) peaks were observed.
(0002) peak was not observed in the both sample.
Discrepancies between the experimental andexpected (JCPDS card) peak position areprobably caused by internal stress in the films.
FWHM values of the (11 2 0) ω-scan rocking curve
were found to be 4.6º. Figure 3 shows the (11 2 2)pole figure of the sample A. FWHM values of
φ-scan profile curve in (112 2) pole of the film werefound to be 23º. These results show high in-planeand out-of-plane (1120) preferred orientation.

0c-axis(1120) AlN layer

1120

600

Al 200800

Al 111

Sample A

1010
0002

1000

Intensity (a.u.)

400
200

Amplitude (dB)-20

JCPDS card No.25-1133 (AlN)
JCPDS card No.4-0787 (Al)ElectrodelayersShearwave Silica glass
substrate

0.5 mm

-40
-60
-80

-100

0
1000

0.00

0.25

Sample B

800
600
400
200
0
20

30

40

50

60

2θ (deg.)70

Fig. 2 XRD patterns of sample A (AlN/Silica glass
substrate) and B (AlN/Al/Silica glass substrate)

Incident
ion beam
direction

0.50

0.75

1.00

Time (µs)φ = 90
60

120

150

30

ψ=

[0001]

0180{1122}

30

60

90

0

{1122}

210

5. Conclusions
This presentation reports the first synthesis of
the in-plane oriented (11 2 0) AlN film on a
non-crystalline substrate. Pure-shear wave
excitation was clearly observed in the thin film
HBAR structure. This film would be suitable foruse in shear mode FBAR sensor or SH-SAW
sensors for measuring liquid. In addtion, this film
can be faricated on various substrate and curved
surface.

Acknowledgment
330

240

Fig. 4 Schematic diagram of pure thickness shear
mode HBAR and impulse response of the resonator.
Longitudinal and shear waves propagate in the
0.5-mm-thick silica glass substrate at respective
velocities of 3770 m/s and 5960 m/s so that theirechoes should be observed at 168 ns and 265 ns,
respectively.

300
270

Intensity (a.u.)

Fig. 3 (11 2 2) pole figure of (11 2 0) textured AlN film
(sample A). The arrows indicate the [0001]
direction in the substrate plane and the incident
ion beam direction.

4. Piezoelectric properties
A Cu film was then evaporated on the sample B
as a top electrode of the HBAR. Figure 4 shows
the impulse response of the resonator, which was
obtained by taking the inverse Fourier transformof the reflection coefficient S11. Shear wave echotrain reflected from the bottom substrate surface
and the top film surface was clearly observed
without any excitation of longitudinal waves.

The authors thank Professor Yoshaki Watanabe
and Professor Mami Matsukawa of Doshisha
University for their valuable collaboration inmeasuring the piezoelectric properties of samples.

References
1. T. Yanagitani, M. Kiuchi, M. Matsukawa, andY. Watanabe: J. Appl. Phys., 102 (2007)
024110.
2. T. Yanagitani and M. Kiuchi: J. Appl. Phys.,
102 (2007) 044115.
3. T. Yanagitani and M. Kiuchi: Jpn. J. Appl.
Phys., 46 (2007) L1167.
4. T. Yanagitani, M. Kiuchi, M. Matsukawa andY. Watanabe: IEEE Trans. Ultrason.,Ferroelect., Freq. Contr. 54 (2007) 1680.
5. A. Tanaka, T. Yanagitani, M. Matsukawa, andY. Watanabe: IEEE Trans. Ultrason.,Ferroelect., Freq. Contr. in press
6. F. Takeda, T. Mori, and T. Takahashi: Jpn. J.
Appl. Phys., 20 (1981) L169.

1P4-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 113- 114
11-13 November, 2008

Development of the Ultrasonic Information Transmission Systemusing One-Chip Microcomputer for Wearable Devices
ワンチップマイコンを用いたウェアラブルデバイス用超音波通信システムの開発
Shin-nosuke Suzuki1‡, Manabu Ishihara1, Yukio Kobayashi1, Tamotsu Katane2, Osami Saito2 andKazuto Kobayashi3 (1Dept. of Elec. and Comp., Oyama N. C. T; 2Faculty of Eng., Chiba Univ. ;3
Honda Electronics co., ltd.)
鈴木真ノ介 1‡，石原学 1，小林幸夫 1，片根保 2，斉藤制海 2，小林和人 3（1 小山高専 電気情報; 2 千葉大 工；
3(株)本多電子）

Wearable Device (WD)
1. Introduction

Piezo Oscillator%

wrist watch
solar battery
memoryIn these days, our daily life is being “Ubiquitous
society” that we can use computers at “any time”
and “any place”. One of the resason is spread of thecellular phones. They are installed with many
functions, such as music player, digital camera, IC
card and electric money. It has evolved from an
only mobile phone to a small computer. In the near
future, it will been mounted into wearing
instrument like a wrist watch. The authors define it“Wearable Device”.
We have been studied about the digital
informationtransmission
using
modulated
ultrasonic1)-2) and applied it to the communicationof the wearable device. In our previous study, thetransmission speed of 115.2 kbps is obtained in the
prototype transmitter, which is using one-chip
microcomputer and assumed the transmission fromthe wearable device to the data reader-writer2).
In this time, we have improved the prototype. The
inprovement points are that adding the receiver
function and higher transmissoin speed, althoughusing one piece of same microcomputer. We havecarried out the communication experiment by new
prototype and obtained the speed of about 2 times
higher than previous model (250 kbps).

bi-directionally. Since the WD can also read andwrite the data, the communication is performed
from one WD to another with the shake hands. It is
assumed that the WD has a solar and a rechargeable
battery and is provided the energy from them.
The system prevents from the leaking of thewearing information because ultrasonic has a large
attenuation in the air. In addition, so the WD canstore several data and include the IC card functionthat the user get rid of the botheration of taking out
the card from the pocket. Furthermore, the systemis effective for the handicap people who have visual
impairments and are using an invalid wheel chairs.
So they wear the WD and hold hands with the third
person who touches the R/W, that thecommunication is enable.

2. System configuration

3. The improved prototype using microcomputer

Figure 1 shows the configuration of the proposedsystem. The system transmits interactive
information using a single path with half-duplex
communication through the human body. The pathis consisting of a pair of piezoelectric ceramic
oscillators. One oscillator is mounted in thewearable device (WD), and another is in thereader-writer (R/W). The communication method is
as follows. When the user touches the R/W with thefinger or the palm of the hand, the digital
information in the each side is transferredFigure 2 shows the circuit diagram of the
improved prototype. The one-chip microcomputer“PIC” (Microchip Technology Inc., PIC16F84A),
is also used previous prototype. It can transmit andreceive the information in order to change the modeof PIC, and communicate between two prototypes
interactively. In this time, They deal with the 8 bit
signel assumed half size character information. The
information transmission of the system is according
to the amplitude shift keying modulation (ASK) andthe detail is as follows.

-----------------------------------------------------------------------E-mail: shin-s@oyama-ct.ac.jp

Reader/Writer(R/W)

Ultrasonic(Information)

Fig. 1 Communication System for Wearable Device.

4.

7
6
Voltage (V)5Power Source

3
2
0
-1
0

20

40

60

80

100

Time (μs)(a) Input of the Transmitter Side PZT.
7
6
5
4
3
2
1
0
-1
0

20

40

60

80

100

Time (μs)(b) Output of the Receiver Side comparator.
Fig.3. Waveforms on the Prototype Experiment.
(250kbps, “01010101”, Finger - Wrist)

Experimental Results

Using two sets of the prototype, the experimentassumed the WD-WD communication is carried out.
It is experimented in a person and one PZT set thewrist and another PZT is touched on the nearest
forefinger. The digtal information is the several
kind of 8bit signal, such as “01010101”. After the
adjustment of the demodulator, signals aretransmitted and the proper LEDs are always lighted.
Therefore, the transmission is success. Then, thetransmission speed is obtained corresponding 250kbps. The waveform sample is shown in Fig. 3. The
signal can be received not only between a wrist anda finger, but also all over the point in the person.
However, the error rate cannot be mesured,

4

1

Voltage (V)The PIC in the one prototype output 0 V from theterminal RB2 for changing the mode “send”.
According to the digital information that stored thememory, the power source voltage is switched. As aresult, the modulated signal is produced. The wave
form is like impluse signal, because of battery
power saving. The signal is input the piezo
oscillator and the modulated ultrasonic wave istransmitted to receiver side through the human body.
The PIC in the another prototype output 5 V fromRB2 for changing the mode “receive”. The receiverside oscillator transforms the received ultrasonicinto electrical signal. The signal is demodulated
thorough the filter, amplifier and comparator. The
demodulated signal input RB0 and the PIC output
the results to RA0~3 (lower 4 bit) and RB4~7(upper 4 bit). The received condition is confermed
from the LEDs that are connected the terminals,.
The piezoelectric ceramic oscillators configurationin this prototype is as follows: Pb (Zr, Ti) O3: PZT,
Resonance frequency 1 MHz, Diameter 20 mm,
thickness 2 mm.

because the same series signal is transmitted andthe received condition is observed only LEDs inthis experiment. For improving the communication
accuracy, mesuring the error rate is absolutly
neccesary. Next step, the constructing the mesuringsystem is need , for example, the personal computeris utilized in the recever side..
5.

Conclusions

In this paper, we proposed the new prototye withtransmitter and receiver using PIC. It can transmit 8
bit signal at the speed of 250 kbps between the two
arbitrary point in a human body. Next step, we plan
to construct the mesuring system introducing
personal computer. In addition, we will try tocommunicate several electrical files in this system.
Acknowledgment
This work was supported by Grant-in-Aid forscientific research from the Ministry of Education,
Culture, Sports, Science and Technology of Japan(No. 19760241)

Transmitter

PZT

ReceiverFig. 2 Transmitter and Receiver Circuit.

References
1) S. Suzuki, M. Ishihara, T. Katane, O. Saito and K.
Kobayashi: Jpn. J. Appl. Phys. 45 (2006) 4550.
2) S. Suzuki, M. Ishihara, T. Katane, O. Saito and K.
Kobayashi: USE2007 (2007) 1-10P-54

1P4-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 115- 116
11-13 November, 2008

Mechanical Transient Analysis of Breaking Contact in a
Magnetic Relay
電磁リレーにおける開離接点の動的挙動の解析
Nobuo Takatsu1†, Noboru Wakatsuki1and Masahiro Oikawa1 (1 School of Sci. Eng.,
Ishimomaki Senshu Univ.)†

高津 宣夫 1 ，若月昇 1，及川 雅弘 1 （1 石巻専修大 理工）

1. Introduction
Breaking arc as well as bounce in a magnetic
relay are difficult problems that have not beensolved. There are many reports on studies of arc
where opening speed of contact is said to be one of
the most important parameters and conventional
designs aim to increase opening velocity to avoid
arc. Nevertheless, there are few reports on
estimating the transient motion of contacts during a
break operation of magnetic relay. One of theauthors developed a device named “Transient
Current Switch (TCS)”, which can suppress breakarcing[1] and using it he has started building a newmodel of an opening contact. In this study, aconventional hinged magnetic relay is modeled by alumped parameter system of 2-DOF and its
dynamic characteristics especially at eary stage of
opening are analyzed numerically.
2. Model of hinged magnetic relay
A hinged magnetic power relay, Fuji Electric
HH62P, is modeled by lumped parameters as shownin Fig.1 (a). The movable contact assembly can beseen as a rotating rigid bar (iron armature) with apair of contacts and leaf springs installed at one end
and a return spring with stiffness kr at the other end.
The moment of inertia J a of the armature aroundsupport O is represented with an equivalentmass ma . The movable contact and leaf spring isassumed to be a cantilever with an equivalentmass m of the contact at its free end. Neglecting

higher modes of the cantilever, its stiffness k can be
defined from deflection under a concentrated loadat the free end. Then m is estimated from thenatural frequency wn of the system, which can be
determined experimentally. Both a- and b- fixedcontacts are modeled by contact stiffnesses kca
and kcb , respectively, including related movable
contact. Assuming the foregoing model, equationsof motion for ma and m are derived. G and
Gs are gaps of contact and armature, respectively.
3. Modeling contact stiffness
A stiffness model of contact is required in theforegoing model. Mechanical modeling of a relay
contact with a rough surface is not a new problem,
but has not been well established. Multi-contact
model [2] seems to be preferable, but estimation ofcontact stiffness for practical application has notbeen verified. Hertz contact between two identicalvirtual spheres with radius R is assumed in thisstudy. R is estimated as follows: So-called Holm’s
radius a of known material (Ag alloy) is estimatedfrom measured value of contact resistance underknown contact force. Then R can be estimated if
a is assumed to be equal to Hertz’s contact radius[3]. For simplicity, a linear contact stiffness
k ca = 250 N/mm is introduced by linearizing thenonlinear relation between the force and relative
approach of the two spheres in the range of actual
contact force.
4. Analysis of break operation
Equations of motion were solved numericallyunder the initial state of “make” shown in Fig.1 (b),where both gaps are fully closed, by removing
magnetic force Fm . Velocities were assumed to be
zero. All electrical effects were ignored. Main
constants of the relay are shown in Table I.
Table I Constants of the target relay
k = 0.77 ´ 10 3 N/m
m = 0.19 ´ 10 3 kgFig. 1 Lumped parameter model of a hinged magnetic
relay, (a) free state, (b) make stateJ a = 72.3 ´ 10 3 kg mm 2
G = 0.6mm, G s = 0.45mm
k r = 0.787N/mm

instant (indicated by a broken line) are 0.7 m m and
5 mm/s, respectively. Fig.3 (d) shows contact
resistance obtained from Holm’s radius.
x 10

-4

6.02

x (m)

Fig.2 show the behavior of moving contact
where all variables are shown in non-dimensionalvariables. The contact remains at rest as shown in
Fig.2 (a) and (b) till the elastic deformation at thecontact disappears (Fig.2(c)). Then contact isaccelerated rapidly at almost constant acceleration
as shown in Fig.2 (b) because the variation of therestoring force at return spring is small. Fig.2 (d)shows repetitive bounce motion at b-contact after
break.

x(m)

(a)
6
5.98
0

0.2

0.4

0.6

0.8

t (s)
1.5
(a)

*

x

*

x

0
0

2

4
6
t = wn t (-)

810Fca (N)

*

v

v

-1

25
20
15
10
5
0

4
6
t = wn t (-)

8

10

8

1
x 10

-3

Fca(N)

0.1

0

0.2

0.4

0.6

0.8

1
x 10

(d)

-3

10

Rc(W)

0.005

0

0

0.2

0.4

0.6
t (s)

0.8

1
x 10

-3

*

(d)

0

0.8

0.01

*

4
6
t = wn t (-)

0.6

0.05

Fca

2

0.4

t (s)

(c)

0

0.2

(c)

0.15

0

Rc (W)

*

Fca

*

Fcb

0.4
0.3
0.2
0.1
0

2

0

0.2

*

(b)

0

-0.05

t (s)

0

-2

v(m/s)

0

-0.1

2
1

(b)

0.05

0.5

-0.5

x 10

0.1

v (m/s)

1

1
-3

Fcb

2

4
6
t = wn t (-)

8

10

Fig.3 Behavior of the contact at early stage of breakin real values. (a) Displacement x . (b) Velocity v .
(c) Contact force Fca . (d) Contact resistance Rc .

Fig.2 Time history of non-dimensional variables ofcontact. (a) Displacement x * = x / G . (b) Velocityv * = v /(w n G ) . (c) Contact force Fca* = Fca /( kG ) .
(d) Contact force Fcb* = Fcb /(kG ) .

Acknowledgment
The authors express their great gratitude to Fuji
Electric FA Components & Systems Co. Ltd. forrelay samples.

We are interested in the dynamic behaviorof the contact at an early stage of break. Fig.3
shows it in real values during one milli-second after
the initiation of break. Displacement and velocity of
the contact are displayed in (a) and (b) respectively
by a magnified scale. Contact force plotted in (c)shows that elastic contact breaks at t = 0.35 ms.
The value of displacement and velocity at that

References
1. Y. Yonezawa and N. Wakatsuki: IEICE Trans.
Electron. E87-C (2004) 1324.
2. J. A. Greenwood and J. H. Tripp: Trans. ASME,
J. Appl. Mech., March (1967) 153.
3. S. P. Timoshenko and J. N. Goodier: Theory of
Elasticity, Third Edition (McGRAW-HILL
KOGAKUSHA, 1970) p.409.

1P9-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 117- 118
11-13 November, 2008

Basic Study on Effect of Current Flow to Time-Reversal
Communication
位相共役通信への流れの影響の基礎検討
Takuya Shimura1, Yoshitaka Watanabe1, Hiroshi Ochi1, and Takehito Hattori2(1 Advanced Marine Technology Research Program, JAMSTEC;
2
Nippon Marine Enterprises, LTD.)
志村拓也 1，渡邊佳孝 1，越智寛 1，服部岳人 2（1 海洋研究開発機構, 先端技術研究プログラム; 2 日本海洋事業）

Simulatoins under current flow in shallow
water using the mehod as described in the previous
section are executed. The environmental conditions
are illustrated in Fig. 1. The flow velocity profiles(FVPs), sound velocity profile (SVP), and the time
reversal array (TRA) configurations are shown in
Fig. 2.
o

The numerical solution of a wide-angle
parabolic equation (WAPE) for moving media aredeveloped by Godin [10] and Mikhin [11]. In thecoordinate as shown in Fig. 1, its parabolic equation
takes the following form────────────────────

100 (m)Sourceρ w = 1.0

15 (km)ρb = 1.5 cb=1600 (m/s)

Fig. 1 Simulation condition.
(a)

0
20

(b)

(c)

1500
1520
1540
Velocity (m/s)

FVP1
FVP2
FVP3
FVP4

)

where ρ ( x, z ) is the medium density, β isdefined as β = 1 − u c0 , c0 is a reference soundspeed, andu(x, z) is the horizontal flow
component. The second order differenctial operatorX̂ is given byshimurat@jamstec.go.jp

z

)

(

u(x, z)x

TRA

Depth (m)(20

3. Simulation conditions

2. Propagation in moving media


∂  1

1 + γ Xˆ ψ  =∂x  ρβ 3


(1)
−1
2 jα k0 ˆjXψ +1 + γ Xˆ β B,
ρβ 3
2k0 ρβ 3

β 

40
60
80
100

0.0 1.0 2.0
Velocity (m/s)

09ch
07ch

The researches on uderwater acoustic
technologies are assigned to our group in Japan
Agency for Marine-Earth Science and Technology(JAMSTEC). Time reveresal communication has
a possibility to realize long horizontal
communication by utilizing multipath signals. We
have studied its basic focusing property [1-5] andexecuted at-sea experiments [6-9].
It is presupposed that the reciprocity of themedia is retained for time reversal process. So, it isnecessary to invesigate the effects of non-reciprocal
disturbances due to, for example, a moving
source-receiver or current flow. The effect of thesource-receiver movement has been researched in
the previous works [4, 5]. In this paper, the current
flow-induced effect are discussed throughsimulations.

∂  2 22 ∂  12
 ρβ + k β − k0  (2)2k ∂z  ρβ ∂z where k0 = ω c0 and k = ω c are the representativeand local wave number, repectively. The horizontal
flow velocity affects sound propagation through βand the vertical flow effect is indirectly included
through the derivatives of ρ , c, and β , although
the vertical flow is not considered directly.
X̂ =

67ch
17ch
33ch

1. Introduction

Fig. 2 (a) FVPs (b) SVP (c) TRA configurations.

Figure 3 is the demodulation result of binary
phase shift keying (BPSK) in the case of 9 channel
TRA. The titles on the left graphs, TR, indicate
using only time reversal focusing effect, while thetitles, TR+AE, on the right graphs indicate using the
proposed method of combining time reversal andadaptive equalizer [2-9]. In the case of TR, it isobserved that the performance becomes degradedand demodulated symbols get indistinguishable as
the flow velocity is faster. In the meantime, in thecase of TR+AE, such flow-induced effect iscompensated and demodulation can be achieved. In
these results, the phase rotation due to current flow
is time-invariant not like in communication with amoving source-receiver [4, 5].
TR+AE

2

2

0

0

-2

-2
-2

(a)

0

2

2

0

0

-2

-2
-2

0

2

-2

2

0

0

-2

-2
-2

0

2

-2

2

0

0

-2

-2

(d)

-2

0

0

2

0

2

TR+AE

TR
2

2

0
0

10

20 30 40 50
Channel Number

60

70

40
30
20

FVP1
FVP2
FVP3
FVP4

10
0

10

20 30 40 50
Channel Number

60

70

Fig. 4 BER and output SNR in case of TR+AE.

TR+AE

2

0.02

5. Summary

TR

(c)

2

TR+AE

TR

(b)

0

FVP1
FVP2
FVP3
FVP4

0.04

0
-2

2

0.06

Output SNR (dB)TR

The bit error rates (BERs) and output SNRsof the proposed method are plotted in Fig. 4, when
TRA channel number is changed. In the case ofeach FVP, it is possible to achieve communication
with no error with at least 17 channel TRA.

BER (%)

4. Simulation results

-2

0

2

Fig. 3 demodulation results in the case of 9 channel
TRA under the flow velocity(a) FVP1, (b) FVP2, (c) FVP3, and (d) FVP4.

Simulatoins of time reversal communicationconsidering current flow are executed. It is shownthat the flow-induced effect can be compensatedand communication can be achieved by the
proposed method. Simulations with other various
conditions will be carried out and at-sea
experiments under current flow will be performed.
References
1. T. Shimura: Acoust. Sci. Technol. 25 (2004) 364.
2. T. Shimura et al.: Jpn. J. Appl. Phys. 44 (2005)
4722.
3. T. Shimura et al.: Acoust. Sci. Technol. 26 (2005)
526.
4. T. Shimura et al.: Jpn. J. Appl. Phys. 45 (2006)
4847.
5. T. Shimura et al.: ECUA2006 (2006) 879.
6. T. Shimura et al.: Jpn. J. Appl. Phys. 46 (2007)
4956.
7. T. Shimura et al.: Jpn. J. Appl. Phys. 47 (2008)
4360.
8. T. Shimura et al.: Oceans/Techno Ocean 2008
(2008).
9. T. Shimura et al.: Acoustics’08 (2008) 699.
10. O. A. Godin: ICTCA ’97 (1997) 329.
11. D. Mikhin: ECUA’98 (1998) 581.

1P9-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 119- 120
11-13 November, 2008

The Effect of the Number of Receiving Channels in
Wideband Acoustic Communication at Deep Sea
深海域の広帯域音響通信における受信チャンネル数の影響についてHiroshi Ochi1†, Yoshitaka Watanabe1, Takuya Shimura1 and Takehito Hattori2 (1 Marine
Technology Center, JAMSTEC; 2 Nippon Marine Enterprises Inc.)†

越智寛 1 ，渡邊佳孝 1，志村拓也 1，服部岳人 2 （1 海洋研究開発機構 海洋工学センター; 2 日本
海洋事業）

1. Introduction
There are various research of underwater
acoustic communication.1,2) Authors also areresearching underwater acoustic communication,
especially short range wideband acoustic
communication.3,4) For controlling ROV by acoustic
signal, it is required high update rate imagetransmission. Our goal is to develop a color imagetransmission system, which can transmit more than
1 color image per second. For this objective, theresearch is in progress based on sea experiment.
Considering the operation response, transmission
range is limited to approximately 500 m. We
assume that the operator will accept transmission
delay of less than 1 second in round trip. In
consideration of this limitation and absorption loss,
the carrier frequency was set to 80 kHz.
An acoustic data transmission experiment using
4-channel receiver was carried out at the depth of
1,000 m in November 2007. Received signals wererecorded in each channel, and results ofpostprocessed demodulation were obtained. In thispaper, it is described that characteristics of thedemodulation with changing the number ofchannels.
2. Outline of the experimentFig.1 shows geometry of the sea experiment.
The transmitter was moored at the near bottom. The
receiver was suspended from R/V “KAIYO” byarmored coaxial cable. Parameters of transmitted
signal are as follows. Carrier frequency is 80 kHz,band width is 40 kHz, and modulation method isquadrature
phase
shift
keying(QPSK).
Transmission rate is 80 kbps. For realizing such a
wideband transmission, tilted toroidal beam
wideband transducer5) is used. The receiver has 4omni-directional hydrophones. And received signals
are recorded in each channel. Demodulation
processing is post-processed by software after
recovering test equipments. Demodulator iscomposed of an adaptive multichannel decision
feedback equalizer (M-DFE), a phase compensatorand a JPEG image decompression unit. Least meansquare (LMS) is selected as an adaptive algorithm.
The receiver position was shifted along with theline of 77º from vertical by controlling ship positionand cable length. Relative received positions areshown in Fig.2. The x-y origin (0, 0) means the
position of the transmitter. Because all of recorded
data were same direction, there is no need forconsidering directivity pattern of the transducer.
3.

Results and discussions

Typical channel response is shown in Fig.3.
There are small multi-paths, which are bottom
reflected wave.
The received data were recorded each 4 channels
respectively, demodulation was processed with
R/V KAIYO

Water depth:
approximatory
1,000mTransmitter

ReceiverTransmission range:
400 - 620m
Direction: 77 degreefrom vertical direction

Fig.1 Geometry of the sea experiment.

Fig.2 Relative position of the receiver. (0,0) as
the transmitter position. △: relative position of
the receiver. Solid line: 77º from vertical.

changing the number of channels for the same
packet. And the total number of transmitted packet
was 20. Fig.4 shows performance of thedemodulator. The x-axis shows average input SNR
and the y-axis shows symbol error rate. In case oferror free, its result is plotted as 10-5 of symbol
error rate. The solid line is calculated value withadditive white Gaussian noise (AWGN) channel.
The result of a single-channel demodulation wasapproximately 3 dB worse than AWGN case. The
result of two-channel demodulation was almost thesame as AWGN case. When the number of channels
become larger, the result of demodulation
performance becomes better. Output SNR is definedas eq. (1), which shows convergence performanceof the demodulator output.

{

E d (n )Correlated value

40
30
20
10
0

0

2

4

6

8

10

12

14

Time [ms]Fig.3 Typical channel response.
(Slant range: 410 m)
0

10

10

-1

10

-2

10

-3

10

-4

10

-5

1Ch
2Ch
3Ch
4Ch
Calc.

Nd

Conclusion

Wideband short range underwater acoustic
data transmission experiment was carried out at
1,000 m depth area. Propagated data was recorded
along with same direction, and 4 channels
respectively. By changing the number of thechannels to use for the demodulation, its
characteristic was provided. When average input
SNR is larger than 10 dB, the result of 4-channel
demodulation was approximately 6 dB better thansingle channel case.
References
1. M. Stojanovic: IEEE J. Oceanic Eng. 21 (1996) 125.
2. D. B. Kilfoyle and B. Baggeroer: IEEE J. Oceanic Eng.
25 (2000) 4.
3. H. Ochi, Y. Watanabe and T. Shimura: Jpn. J. Appl.
Phys. 44 (2005) 4689.
4. H. Ochi, Y. Watanabe and T. Shimura: Proc. 8th ECUA(2006) 849.
5. H. Ochi and T. Fukuchi: Jpn. J. Appl. Phys. 46 (2007)
4961.

4

6

8

10

12

14

16

18

average input SNR [dB]Fig.4 Symbol error rate vs average input SNR.
(transmission rate: 80 kbps)
20
1Ch
2Ch
3Ch
4Ch

15

output SNR [dB]

4.

50

}

,
(1)
2
1
ˆ
å d (n) - d (n)N d n =1
where, Nd is the number of symbols in one packet,
d(n) is the correct symbol value, d̂ (n ) is estimatedvalue by M-DFE. Fig.5 shows output SNR vsaverage input SNR characteristic. The result of themulti-channel demodulation shows a goodcharacteristic than less number of receiving channel.
When average input SNR is 8 dB, it can’t
demodulate in single channel demodulation. But in
4-channel demodulation, it still keep 10-4 order
symbol error rate.

Ch1
Ch2
Ch3
Ch4

60

symbol error rate

outputSNR = 10 log

2

70

10

5

0

0

5
10
15
average input SNR [dB]Fig.5 Output SNR vs average input SNR

20

1P9-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 121- 122
11-13 November, 2008

Temporal Coherence Variation for Sea Surface Fluctuation
Jihyun Park, Jong R. Yoon†, Kyongbeak Ryu and 1Joung-Soo Park
(Pukyong National University, Korea; 1Agency for Defense Development, Korea)

1. Introduction
Temporal coherence of acoustic signals in
the ocean has an effect on the performance ofunderwater communication systems and it has beenstudied experimentally in the ocean [1-4]. In thispaper, temporal coherence variation due to only thesea surface fluctuation is presented. By using
directional source and with highly absorptive
bottom, bottom scattering effect could be ignored.
Volume scattering from such as biological scatters
are also ignored.
Fig. 2. Sound speed profiles derived from XBTcasts over the period of 5 hours experiment.

2. Experimental conditions
Figs. 1 and 2 show schematic diagram ofexperimental configuration and sound speed
profiles derived from XBT casts over the period of
5 hours experiment, respectively. Water depth isabout 170m. Wind speed is about 15~16 knots at
15.5m height from sea level. Surface wave direction
to source to receiver direction is parallel in initialstage and 70 degree direction in final stage of 5 hrs
experiment.
7kHz tone burst signals are transmitted fromthe source which consists of 21 elements to give
directional beam. The length of the burst is variablefrom 1ms to 1s. The burst interval is also variablefrom 1s to 30s. The vertical line array of thereceiver consists of 10 elements with 10.7cm
spacing.

Fig.1 Schematicconfiguration.

diagramofexperimental

Fig. 3 shows ray traces and time delays
from source to receiver assuming a constant
1500m/s sound speed and 170m depth of water withmud bottom.
-----------------------------------------------------------jryoon@pknu.ac.kr

Fig. 3 Ray traces from source to receiver.
3. Temporal coherence

For this study, 2ms CW bursts whose
bandwidth is about 1kHz, are transmitted at a
temporal delay rate of 2s. Figs. 4 and 5 show
received signal samples in which the direct and thesurface reflection paths are dominant paths andsurface reflection paths are variant with temporaldelay. The coherence between direct path signal
Rd (t ) and surface reflection path signal Rs (t ) at
each transmitted pulse, is defined in terms of thecross correlation function
K

C d , s (τ ) = ∑ Rd (τ ) Rs (k + τ ) .

(1)

k =− KThe cross correlation function is then normalized togive a correlation coefficientρ d , s (τ ) = C d , s (τ ) / C d ,d (0)C s , s (0) .

(2)

Temporal coherence is given by maximum value ofthe correlation coefficientρ d , s (τ ) max . The

temporal coherence as a function of temporal delay
is examined for 150 delays of 5min. Fig. 6 shows
the mean coherence of all receivers as a function of
temporal delay. Its mean for 150 delay of 5min is
about 0.9.

The fluctuation of the coherence withtemporal delay will be consistent with sea surface
fluctuation. Dominant wave height and frequency
by Pierson-Moskowitz sea surface spectrum are
1.34m, and 0.177Hz for experimental wind speed
about 15~16 knots at 15.5m above sea level. Fig. 7
shows the spectrum of the mean coherence
variation and its dominant frequency is wellconsistent with the sea surface dominant frequencyof 0.177Hz.

Figure 7. Mean coherence spectrum.
Fig. 4 Received signal samples of order number
receivers of VLA.

4. Conclusions
Temporal coherence variation due to sea
surface fluctuation is examined experimentally. 7
kHz, 2ms CW burst signal whose bandwidth isabout 1kHz, is used. Mean coherence is about 0.9
for grazing angle of 16 0 and wind speed of 15~16
knots. Its dominant variation frequency is wellconsistent with dominant sea surface wave
frequency.
Acknowledgment
This work was supported by Defense
Acquisition Program Administration and Agency
for Defense Development under the contract
UD070054AD.

Fig. 5 Signal variation with temporal delay.

Figure 6. Mean coherence of all receivers withrespect to temporal delay.

References
1. L. Culver and D. Bradley ： High Frequency
Ocean Acoustics Conference AIP Conference
Proceedings Vol. 728(2004) p. 204.
2. R. Heitsenrether and M. Badiey：High Frequency
Ocean Acoustics Conference AIP Conference
Proceedings Vol. 728(2004) p. 214.
3. T. Ruppel, S. Stanic, G. Norton, R. Meredith, E.
Kennedy, R. Goodman and M. Wilson ：High
Frequency Ocean Acoustics Conference AIP
Conference Proceedings Vol. 728(2004) p. 413.
4. H. Chandler, E. Kennedy, R. Meredith, R.
Goodman and S. Stanic ：High Frequency Ocean
Acoustics
Conference
AIP
Conference
Proceedings Vol. 728(2004) p. 420.

1P9-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 123- 124
11-13 November, 2008

Numerical Analysis of Pulse Wave Propagated in
Luzow-Holm Bay of Antarctic Ocean
南極リツォホルム湾における伝搬パルス波の数値解析
Takenobu Tsuchiya1, Mari Takahashi1†, Shuki Ushio2, Tetsuo Anada1 and Nobuyuki
Endoh1 (1 Facult. Eng., Kanagawa Univ.; 2NIPR)

土屋健伸 1，高橋茉里 1†，牛尾収輝 2 ，穴田哲夫 1，遠藤信行 1（1 神奈川大 工; 2 国立極地研究所）

Sound velocity [m/s]
0

1440

1450

Sound velocity [m/s]

1460

1436
0

1438

1440

1442

1444

1446

20

100
Aug
Oct

200

Sep
Nov

40
60

300

Depth [m]It is important to know the phenomenonof Ocean climate in the Antarctic Ocean, because
polar region was large influenced to the energy
circulation of the global climate. Therefore,
measurement of oceanic environment carried out in
the Antarctic Ocean by many countries. For
example, in 1991, the Japanese Antarctic Research
Expedition (JARE-31) conducted a two-year
program of atmosphere /sea-ice/ocean study in the
Antarctic Ocean [1]. However, the large area
observation under the sea ice is very difficult,because it is very hard to go in site to the researchship, and to measure environmental data under
sea-ice floor.
Recently, the climate research of Ocean using
Autonomous Underwater Vogel (AUV) is being
planned in the Antarctic Ocean[2]. The underwatercommunication is the only method to distant control
AUV in sea-water, and the research of the
improvement of the transmission rate in underwatercommunication was developed. In order to know
the characteristics of sound propagation in the
Antarctic Ocean for communicate to AUV, we were
calculated propagation time and amplitude of pulse
used by parabolic equation method. We haveinvestigated about the influence of barthmetry forsound propagation in the Antarctic Ocean modelthat was covered ice surface for 33 km in range.

by measurement data using Del-Grosso equation.
As shown in Fig. 1(a), the bottom depth of OW5 isabout 785 m which measured water temperatureand the salinity at the ocean side. The watertemperature of sea surface about -1.8 degrees C,
and it is changed rapidly near sea surface. Whendepth is higher than 100 m, water temperature wasconstant value which is about -0.5 degrees C.
Sound velocity profile has changed almost linearly.
In Generic Ocean, velocity profile of depth
direction depends on the water pressure, watertemperature, and salinity of this ocean.
Measurement point OW5 has constant value oftemperature higher than 100 m of depth. Therefore,sound velocity only depends on water pressure in
OW5. The bottom depth of OW1, which is locatednear bay side, is about 185 m as shown in Fig. 1 (b).
The difference of sound velocity by the season isvery small.

Depth [m]1. Introduction

400
500

80
100
120
140

600

160

2. Environment of Lűtzow-Holm bay

700

Observations of marine environments arebeing by the national polar region laboratory in theSouth Pole from 1989 to 1992. The Japanese
Antarctic
Research
Expedition(JARE-31)
conducted a two-year program of atmosphere/sea-ice/ocean study in Lűtzow-Holm bay and in its
surrounding sea of the Antarctic Ocean. The
purpose of this study is to understand a geophysicalrole of ice-covered ocean in the processes of the
Antarctic Ocean climate.
The sound velocity profiles of Lűtzow-Holmbay are shown in Fig. 1. The profile was calculated------------------------------------------------------------

800

kenshin@kanagawa-u.ac.jp

Sea depth 158 m

Sea depth 758 m

180
200

(a) OW5(b) OW1

Fig. 1 Sound velocity profile of Lűtzow-Holm bay
3.

Calculation results

In this simulation, in order to investigateof the characteristics of sound propagation inLűtzow-Holm bay, we calculated sound pressure
filed by PE method with two ocean bottom models
that were varied the depth of sea bottom andacoustical parameter. In the case1, sea bottom is flat,
which was defined by Range-Independent (RI)
model. In the case2, the depth of sea bottom wasIn order to know the characteristics of soundpropagation in Antarctic Ocean, we will know thecharacteristics of sound propagation in the Antarctic
Ocean. We calculated to obtain the characteristics
of sound propagation in the Antarctic Ocean using
PE method.
It is shown that sound pressure distribution
obtained by PE method was influenced by bottom
shape. In order to obtain the accuracy heavier ofsound propagation in Antarctic Ocean, we calculate
pulse waveform by PE method to propagate in the
Antarctic Ocean using inversion Fourier transfer inthree bottom model. As a result, amplitude of soundpulse was different to three cases. The difference
value was -3dB between RD model and RI model.
In order to know the characteristics of soundpropagation in Antarctic Ocean more accurately, it
is necessary to use measurement data ofenvironment.
Acknowledgment
This study was partly supported by
High-Tech Research Centre Project from the
Ministry of Education, Culture, Sports, Science andTechnology, Japan.
References
1. T. Shimura, et. al., JJAP，45（5B），4847-4852，

750
1000
5

10

15

20

25

30

35

Distance [km]

-80

-65

-50

-35

-20

Sound pressure [dB]Fig. 2 calculation results of sound pressure
distribution of transverse line OW in Lűtzow-Holmbay by PE method in the cases of RD model.
100(a) Range-dependent model

Relative amplitude

Conclusions

500

80
60
40
20
0
27.00

27.05

27.10

27.15

27.20

27.25

27.30

27.25

27.30

Time [sec.]

100(b) Range-independent model
80

Relative amplitude

4.

250
Depth [m]assumed by measurement data which was definedby Range-Dependent (RD) model. The depth of thesound source was assumed to be 100m in bothtraverse line. In these cases of RD model and RI
model, acoustical parameter of bottom assumed
1700 m/s in sound velocity and 1.5 g/cm3 indensity.
Figure 2 shows the calculation results ofsound pressure distribution of transverse line OW inLűtzow-Holm bay by PE method in the cases of RD
model. The d istribution of sound pressure werechanged near source depth, because amplitude ofsound pulse reflected from sea bottom is large, sothat RD model has upslope bottom shape.
Figure 3 shows estimated waveform topropagate in the Antarctic Ocean by parabolic
equation method with inversion Fourier transfer. In
this case, we calculated sound propagation assumed
three bottom models Fig. 3 (a) shows estimatedpulse waveform in the case of RD model. It is
assumed that bottom depth data was used bymeasurement data. Fig. 3 (b) shows estimated pulse
waveform in the case of RI model. This model was
assumed the float bottom shape in the bottom depth
in source point. The difference value was -3dB
between RD model and RI model.

60
40
20
0
27.00

27.05

27.10

27.15

27.20

Time [sec.]

Fig. 3 Estimation of pulse waveform propagated in
Lutzow -Holm bay on transverse line ‘OW’.
2006．
2. S. USHIO and T. TAKIZAWA, “JARE DATAREPORTS NO. 184 (Oceanography 13),” NIPR，
1993．

1P9-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 125- 126
11-13 November, 2008

Influence on Sound Field by Number and Interval of Internal Waves
音場に対する内部波の数と間隔の影響
Yoshiaki Tsurugaya1†, Toshiaki Kikuchi2 and Koichi Mizutani3 (1NEC; 2NDA; 3Univ. of Tsukuba.)
鶴ヶ谷芳昭 1‡，菊池年晃 2，水谷孝一３ (1NEC; 2 防衛大; 3 筑波大）

1. Introduction

2. Internal waves (IWs)The echo-sounder trace of IWs taken
New York Bight, southeast of New York near
the edge of the continental shelf3) is shown in
Fig. 1. The character of the waves is clearlyvisible, with only downgoing pulses appearing
and very little upgoing excursion. In manycases, an internal wave train (a solibore) is
formed rather than a single IW.

1500kg/m3 of sandy
silt,
respectively.
Absorption coefficientis 1.0dB/λ. Wavelengthand amplitude of IW
are 100m and 22.5m
referring to the value ofIWs5) , respectively. As
for the examination of
the influence, the soundfields of one IW and
two IWs with theintervals of 0m, 100m,
and
200m
were
compared respectively.
Water depth is 200m.

音速(m/s)1510 1540
0

100m
22.5m

深度（ｍ）

Internal waves in the ocean is a wave motion
generated on the density interface in underwater.
Many studies has been performed in the field ofgeophysics for a physical property of internal waves(IWs)1). In recent years, IWs in the continental shelfand the littoral region is widely confirmed with thesensor equipped with a satellite, and it pays
attention to an influence on sound propagation2).
The studies of the influence to the soundpropagation are performed about the fluctuation to
the propagation time and the remote sensing of IW
using acoustics. However, a study of the influenceon sound field by the modification in the state ofIWs has not being performed. Then, in relatively
short range (<10km) using active sonar such as fish
finders, the influence on sound field is examined by
the state variation of the number of IWs and theinterval between IWs. The influence by IWs was
examined by assuming IWs approaching to thesound source, and comparing the sound field with
IWs and the sound field without one.

100

200

海底
α＝1.0dB/λFig. 2 Sound speed
profile and parameters.

4. Sound field without IW

For the simulation, used frequency is 600Hz
and the simulation model is FOR3D6) of the PE
model. The sound field by sound source in thethermocline, 50m in depth, is shown in Fig. 3. In
200m to 2km, there is an overlap of the sound wavethat reflect at the surface or refract in the vicinity ofsurface and changes the direction to downward.
And, the propagation of sound wave iterates thereflection at the bottom and the surface. Moreover,the surface duct is formed between sea surface andthe lower side of the thermocline. In the area of
6km or more, sound field below the thermocline isformed with the propagation by reflections and theleakage from the lower side of the thermocline

Fig. 1 Echo-sounder trace of IWs.
3. Parameters of IWs

The parameters used to examine of IWs areshown in Fig. 2. Sound speed profile in shallow
water is used the value of reference4), and soundspeed and density in the bottom is 1500m/s and-----------------------------------------------------------y-tsurugaya@bp.jp.nec.com

Fig. 3 Sound field without IW in sound source
depth 50m.
5. Sound field with IWs

Subtracted sound field that the sound field
without IW was subtracted from the sound fieldwith IW is shown in Fig. 4. The refraction of the(a) 2-1

Fig. 4 Subtracted sound field without IW fromsound field with IW. range; 3km sound source
depth; 50m

sound wave to the upper part and to the under isemphasized by IW fields because of sound source
50m in depth. Considering the change in phase, in
depth that is shallower than sound source, modes isshifted to the low-order mode because of theshallower angle of refraction, and in depth that isdeeper than sound source, modes is shifted to thehigh-order mode because of the deeper angle ofrefraction. Therefore, the sound field under thethermocline is formed with sound wave changing
the direction of propagation and sound wave
leaking from under the thermocline. The sound field
where the sound field of one IW was subtracted
from the sound field of two IWs and the sound field
where the sound field of two IWs with 100m
intervals subtracted from the sound field of thatwith 200m intervals are shown in Fig. 5. As
shown in Fig. 5(a), the strength and the range ofrefraction increase in sound field with consecutive
IWs because the consecutive IWs fields broadensmore than the one IW fields. Moreover, the soundpressure level under the thermocline increases
because the refraction of the sound wave from theduct is emphasized. In Fig. 5(b)), there is no
substantial change in upward refraction in soundfield with 100m intervals, but three strong soundfields are generated in downward refraction. As for
this, because the internal wave is only 100m away,
the refraction by the second internal wave issuperimposed. On the interval 200m（Fig. 5(c)）,
compared with the case of the interval 100m, thestrength pattern does not become clear though the
influence of the refraction by two IWs is generated.
In the difference of the sound field of the interval
100m and the interval 200m(Fig. 5(d)), sound fieldof the intervals 100m is appeared strongly because
the sound wave reflected at sea surface and thesecond internal wave fields was overlapped.
6. Summary
The influence on the sound field of theconsecutive IWs was examined. The sound field
without IW and with IWs were compared, and the(b) 2100-1(c) 2200-1(d)2200-2100

Fig. 5 Subtracted sound field. (a)sound field of 2
consecutive IWs and that of 1 IW (b) 2 consecutive
IWS with the 100m intervals and 1 IW (c) 2consecutive IWs with the 200m intervals and 1 IW(d) 2 consecutive IWs with 100 and 200m intervals

sound field having different intervals of IWs arecompared respectively. As a result, the position
between the position of sound field without IW and
the internal wave fields is important in the soundfield formation. Moreover, considering from thestates of the phase, the shifting to the low-ordermode by the refraction to the upper side and to thehigh-order mode by the refraction to the lower side
became clear.
References
1. C. R. Jackson et al., Internalwave Atlas. 2nd ed.,(2004).
2. J. R. Apel et al., J. Acoust. Soc. Am., 121(2)(2007)696．
3. R. F. Gasparovic et al., Science, 232(1986)1529．
4. F. B. Jensen et al., “Computational Ocean
Acoustics” , AIP PRESS, 1994．
5. J. R. Apel, “Oceanographic Applications ofRemote Sensing”, CRC Press, 1995．
6. D. Lee et al., “Numerical Ocean Acoustic
Propagation in Three Dimension”, World
Scientific, 1995．

1P9-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 127- 128
11-13 November, 2008

Tidal Effect of Sound Propagation at Hashirimizu Port
走水港内音波伝搬における潮汐の影響
Hanako Ogasawara1‡, Toshiaki Nakamura1, Kazuyoshi Mori1 and Koichi Mizutani2(1 National Defense Academy; 2Univ. Tsukuba)
小笠原英子1‡，中村敏明1，森和義1，水谷孝一2 (1防衛大 地球海洋; 2筑波大 シス情工)

1. Introduction
At the ocean, acoustic methods have been usedin many ways such as signal communication,
environmental monitoring tools, and detection systembecause of its advantage that it is less attenuation than
optics or radiowave. We had analyzed reciprocalsound data which was traveling more than 100 km
retrieved in the equatorial central Pacific Ocean while
a whole year in 20001-4). However, refraction andreflection from the sea surface and seabed complicate
the received signals especially at the shallow water.
Therefore, many ocean experiment5, 6) andsimulation7) were executed to clarify these effect andsound propagation. As sea surface level dynamicallychange because of the tidal effect, the effects ofrefraction and reflection also alter with time. In thisstudy, we show some results caused by tidal changes
from a small scale sound propagation experiment at
Hashirimizu port.

2. Experimental result
A pair of a sound propagation system wasplaced on either bank of Hashirmizu port with the
distance of about 120 m. Depth of the port is about 5
m in average as shown in Fig. 1. Depth of the
propagation area was measured every 5 m between the
propagation systems. As the seabed covers with madand sand, the shape of the seabed is very smooth.
Transducer was placed at the depth of about 0.9 m
from the seabed. Sending signal is seventh orderM-sequence and repeated for four times. The signal
was sent with the career frequency of 80 kHz.
The systems alternate sending and receiving
every 30 s; we can get reciprocal sound propagation
data every 1 min. Received signal is recorded for 300
ms after the sending start with the sampling rate of 1
MHz. To synchronize both side of the system, a global
positioning system (GPS) clock generates 1 pulse persecond signal with accuracy of ± 200 ns. Therefore,
it is able to detect the accurate travel time between thesystems.
M-sequence modulated signal has an advantage
in measuring accurate travel time in the noisy
environment because it can be treated as a pulse after-----------------------------------------------------------ogasawar@nda.ac.jp

demodulation by the original M-sequence. As sending
signal include 4 times of M-sequence signal, recorded
signal was cut the length of one cycle M-sequence andadded all of the cut signals. Effects of spicular noises
and other noises can be almost removed by theseprocesses. The added signal were demodulated with
M-sequence and transformed to get amplitude
components.
Figure 2 shows the travel time changing
through the experimental period of 4th-20th August in
2007. At the same time, water temperature at the sea
surface, depth around the transducer, and the seabedwere measured every 2 min and plotted by dashed line,
gray line and solid line, respectively on Fig. 2(b).
Figure 2(c) shows the depth between the transducer
and the sea surface monitored by conductivity
temperature depth meter (CTD) near the transducer
every 5 min. Gray scale indicates the amplitude of thesignals in Fig. 2(a). White part means strong
amplitude and black part means weak amplitude. The
first strong amplitude appeared around 75 ms. The
first white band located at the front of the black partaround 75.2 ms are the point of the direct pass.
Distance between the systems is calculated as 114.5 m
from the sound speed calculated by McKenzie’s
equation8) with average temperature 24 ℃ andaverage salinity 30.5 ‰ at the depth of 2 m. As theaccurate measurement between the systems by a laser
distance meter shows 116.3 m, acoustic monitoring
result has validity.

Fig. 1 Propagation area and arrangement of experimental
equipments.

Discussion

Tracking the first white band, travel time varies
according to the changes of water temperature in Fig.
2(b). But in some part, the first arrival amplitude
suddenly disappeared such as around noon of 15th and16th August as indicated by white arrows in Fig. 2(a).
In such period, it is confirmed that water verticalgradient of water temperature is steep shown asarrows in Fig. 2(b) and depth from the transducer tothe sea surface is very shallow given as Fig. 2(c). It is
assumed that the direct pass could not reach thereceived transducer because high vertical temperature
gradient refracts the propagating sound. Furthermore,
the very shallow depth because of the tidal effectseems to make refracted sound into the seabed.
Ray paths in two characteristic conditions arecalculated by a ray tracing program, Bellhop9) are
figured in Fig. 3. Sound speed profiles, which are
shown on the right side of Fig. 3, are calculated withtemperature profiles which are created by linerinterpolation with the three measured temperature bythermometers. Temperature at points deeper than themeasured depth assumed as the same temperature of
the measured at seabed. As depth of the water isdecided from CTD data, depth of 0 m means sea
surface. In Fig.3(a), temperature gradient is small andhigh tide. On the other hand, temperature gradientnear sea surface has high gradient at low tide in Fig.
3(b). Though we can confirm direct pass in Fig. 3(a),all passes are refracted and cannot propagate directlyin Fig. 3(b). Because of low tide, high temperature
gradient caused by sun-warmed water directly affects
sound propagation. If it had enough depth between thetransducer and the surface, some rays would travel
directly without any reflection.

(a)

(b)

(c)
Fig.2 (a) Extracted amplitude of received signals
correlated with M-sequence. (b) Water temperature atsea side. (Solid line) water temperature around seabed,(gray line) water temperature near the transducer,(dashed line) water temperature near the sea surface. (c)Distance between the surface and the transducer.
01

Depth (m)

3.

2

3

4

(a)

5
0

20

40

60

80

100

120 1530 1535
Sound speed
(m/s)

80

100

120 1530 1535
Sound speed(m/s)

Range (m)01Conclusion

Travel time changes related to the depth of thetransducers and temperature gradient. Under thecondition of high temperature gradient and low tide,
direct passes disappeared because all passes are
refracted to downward and reflect at the seabed.
Bellhop model explains this result. We will calculate
other conditons of depth and temperature gradient for
detail explanation.
References
1. H. Ogasawara, T. Nakamura, H. Hachiya, H. Fujimori, K.
Mizutani, Jpn. J. Appl. Phys. 47, (2008) 4349-4353.
2. H. Ogasawara, T. Nakamura, H. Fujimori, K. Mizutani, Proc.
Int. Congress on Ultrasonics, (2007) ID 1254.
3. H. Ogasawara, T. Nakamura, H. Fujimori, K. Mizutani, Jpn.
J. Appl. Phys. 46, (2007) 4998-5003.
4. H. Ogasawara, T. Nakamura, H. Hachiya, H. Fujimori, K.
Mizutani, Jpn. J. Appl. Phys. 45, (2006) 4842-4846.
5. B. D. Dushaw, B. D. Cornuelle, P. F. Worcester, B. M. Howe,D. S. Juther, J. Phys. Oceanogr. 25, (2005) 631-647.
6. B. D. Dushaw, Deep-Sea Res. I 53, (2006) 449-473.

Depth (m)

4.

2

3

4

(b)

5
0

20

40

60

Range (m)Fig. 3 Rays calculated by Bellhop under the parametersof temperature and depth at (a) 6:00 and (b) 14:00 on
August 16, 2007. Graph on the right side shows soundspeed profile in the water used for calculation.
7. F. Iijima, T. Tsuchiya, N. Endoh, Jpn. J. Appl. Phys. 39,(2000) 3200-3204.
8. K. V. Mackenzie, J. Acoust. Soc. Am. 70, (1981) 807-812.
9. M. B. Porter and Y. Liu: in Theoretical and Computational
Acoustics Vol. 2, ed. D. Lee and M. H. Schultz (World
Scientific Publishing, 1994) pp.947-956.

1P5-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 129- 130
11-13 November, 2008

Development of Small-sized SAW Duplexer
SiO 2/Al/LiNbO 3 str ucture for Band IV systemon

SiO2/Al/LiNbO3 構造を用いた Band IV 用小型 SAW デュプレク
サの開発
Hidekazu Nakanishi†, Hiroyuki Nakamura, Tetsuya Tsurunari, Hiroki Kamiguchi,
Yosuke Hamaoka, Rei Goto and Yukio Iwasaki (Panasonic Electronic Devices Co.,Ltd.)

中西秀和‡，中村弘幸，鶴成哲也，上口洋輝，濱岡陽介，後藤令，岩崎行緒 （ﾊﾟﾅｿﾆｯｸ ｴﾚｸﾄﾛﾆｯｸ
ﾃﾞﾊﾞｲｽ㈱）1. Introduction

2. Char acter istics of SAW resonator of Band I
and Band IV frequency bands
Table 1 shows frequency allocations of Band I andBand IV. Rx band is the same frequency band. On
the other hand, Tx band of Band IV is much lower
than one of Band I. When the same electrode
thickness (160nm) of Band I is applied to Band IV,
as shown Fig.1, the characteristic of SAW resonatorof Band IV degrades. Especially, an attenuation at
anti-resonant frequency degrades.
Firstly, we studied the degrading factor of SAW
resonator. We focused on a phase velocity ofanti-resonant frequency (Va) for resonators. A phasevelocity is calculated by Eq. (1).
-----------------------------------------------------------nakanishi.hidekazu@jp.panasonic.com

Table 1Frequency allocations

Operation bandTx bandRx band1920MHz-1980MHz 2110MHz-2170MHz
BandⅠ
1710MHz-1755MHz 2110MHz-2155MHzBandⅣ

S21 [dB]

The SAW duplexer is a key device of the mobile
phones for miniaturization and high performances.
In UMTS (Universal Mobile Telecommunication
System), each band can be separated into threegroups, which have wide duplex gap, moderate
duplex gap and narrow duplex gap according tofeatures. Band I and Band IV systems have a wide
duplex gap. Therefore, to realize the small-sized
SAW duplexers with low insertion loss and highattenuation,
thesubstratewithhighelectro-mechanical coupling coefficient (K2) andsmall temperature coefficient of frequency (TCF) isneeded. Recently, a combination of a rotated Y-cut
LiNbO3 substrate and SiO2 film for wideband
applications is reported.1) For Band I duplexer
application, a flattened SiO2 film /Cu
electrode/LiNbO3 structure2) and a shape controlled
SiO2 film /Al electrode/LiNbO3 structure3) werereported. On the other hands, for Band IV duplexer
application, these substrates have never beenreported. In this report, the Al electrode thickness
was optimized to realize excellent duplexer forBand IV by using a shape controlled SiO2 film/Al
electrode/LiNbO3 structure. And, we developed
small-sized SAW duplexer for Band IV system.

0
-5
-10
-15
-20
-25
BandⅠ Resonator-30
BandⅣ Resonator-35
1600 1700 1800 1900 2000 2100 2200
Frequency [MHz]Fig. 1

Characteristics of SAW resonator

Va = f × (2 × p)

(1)

f: anti-resonant frequency
p: IDT pitch(Band I : 1.0μm, Band IV: 1.1μm)
As a result, Va of SAW resonator of Band I is
4007m/sec, Va of SAW resonator of Band IV is4072m/sec. Va of SAW resonator of Band IV isfaster than a phase velocity of slow shear wave of
LiNbO3 (4024m/sec). This is attributed to thinelectrode thickness for Band IV. Thus, a bulk
radiation occurs at anti-resonant frequency of SAW
resonator of Band IV. Because of a bulk radiation,
an attenuation at anti-resonant frequency degrades.
Therefore, to realize a good performance SAW
resonator of Band IV, it is necessary to determine
the electrode thickness or SiO2 thickness so that Va
is slower than a phase velocity of slow shear waveof the LiNbO3 substrate.

1600

-15
-20
160nm
200nm
240nm

-25
-30
1600

1700
1800
1900
2000
Frequency [MHz]Fig. 2 Characteristics of SAW resonator of Band IV

ANT → Rx [dB]

S21 [dB]

-10

1800
2000
Frequency [MHz]2200

Fig. 4 Tx characteristic of the SAW duplexer

0
-5

0
-1
-2
-3
-4
-5
-6
-7
-8

Tx → ANT [dB]

0
-10
-20
-30
-40
-50
-60
-70
-80

0
-10
-20
-30
-40
-50
-60
-70
-80

0
-1
-2
-3
-4
-5
-6
-7
-8

ANT → Rx [dB]

We optimized the electrode thickness so that Va isslower than a phase velocity of slow shear wave of
LiNbO3 substrate. Here, SiO2 thickness is constantof 400nm. Fig.2 shows the characteristics of SAW
resonator when the electrode thickness is 160nm,
200nm and 240nm. Fig.3 shows a phase velocity at
anti-resonant frequency of each condition. And,dashed-line is a phase velocity of slow shear wave
LiNbO3. When the electrode thickness is 200nm
and 240nm, attenuations at anti-resonant frequency
are better. However, when the electrode thickness is
160nm, it degrades. Because, as shown Fig.3, Va
becomes slower than a phase velocity of slow shear
wave of LiNbO3 when the electrode thickness is
200nm and 240nm. Especially, a characteristic of
SAW resonator is excellent when the electrode
thickness is 200nm. And, coupling factor is enoughlarge of 14%

In Tx characteristics, insertion loss and attenuationin Rx band are 1.2dB and 45dB. In Rx
characteristics, insertion loss and attenuation in Tx
band are 2.2dB and 42dB. The duplexer has small
TCF, which is almost same value of Band I
duplexer. 3)

Tx → ANT [dB]

2. Optimization the electrode thickness

1600

Fig. 5

1800
2000
2200
Frequency [MHz]Rx characteristic of the SAW duplexer

4. Conclusion

Phase velocity [m/sec]

4100
4050
4000
3950
3900
100

150
200
250
300
Electrode thickness [nm]Fig. 3 A phase velocity dependenceof the electrode thickness

3. Char acter istics of the SAW Duplexer
The small-sized Band IV SAW duplexer was
fabricated by using the resonator with optimized
SiO2/Al/LiNbO3 structure. The package size of theduplexer is small of 2.5×2.0×0.5mm. Fig.4 andFig.5 show Tx and Rx characteristics, respectively.

The SAW resonator with good performance wasrealized by optimizing the electrode thickness on
SiO2/Al/LiNbO3 structure from a viewpoint of aphase velocity. Applying the SAW resonator, theSAW duplexer, which has excellent performancesof low insertion loss, high attenuation andsmall-sized, could be realized.

References
1. K. Yamanouchi, Y. Satoh, H. Isono and D.
Kawasaki: Jpn. J. Appl. Phys. 44 (2005) 4520.
2. M. Kadota, T. Nakao, K. Nishiyama, S. Kido, M.
Kato, R. Omote, H. Yonekura, N. Takada and R.
Kita: Jpn. J. Appl. Phys. 46 (2007) 4714.
3. H. Nakamura, H. Nakanishi, T. Tsurunari, K.
Matsunami, Y. Iwasaki, K. Hashimoto and M.
Yamaguchi: Jpn. J. Appl. Phys. 47 (2008) 4052.

1P5-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 131- 132
11-13 November, 2008

Improvement of Shape Factor of SAW Resonator Filter
composed of SiO2/High-density-electrode/LiTaO3
SiO2/高密度電極 /LiTaO3 構造共振子SAW フィルタの肩特性改善
Takaki Murata‡, Michio Kadota, Takeshi Nakao, and Kenji Matsuda(Murata Mfg. Co., Ltd.)村田崇基，門田道雄，中尾武志，松田賢二（村田製作所）

2. Filter Design
2.1 Suppression of transverse response
The filter characteristic for MediaFLOTM using theconventional Al-electrode/36º-48ºY·X-LiTaO3 substrateis shown in Fig. 1. A transversal response is observed at
higher frequency from pass band. The filter consists of acascaded two DMS filters, where each DMS filter is alongitudinally coupled resonator as roughly shown in Fig.
2. Figures 3 and 4 show the calculated reflection
takaki_murata@murata.co.jp

0

0

-20

-4

-40

-8

-60
-80
679

Magnitude
Insertion
loss [dB][dB]

Recent years, surface acoustic wave (SAW) filterssuch as radio frequency (RF) ones and duplexers havebeen applied to mobile phones, global positioning system(GPS), Bluetooth (BT) and so on, because of their small
size, good performance, and reasonable price. A leaky
SAW (LSAW) on a 36º-48ºY·X-LiTaO3 and a 50º70ºY·X-LiNbO3 substrates are widely used to theirapplications with wideband characteristic. However, they
are not so suitable for some of the applications, because
their temperature coefficient of frequency (TCF) are poor
as about -40 and -80ppm/ºC, respectively. By depositinga SiO2 film with positive TCF on LiNbO3 and LiTaO3
substrates with negative TCF, the TCF of transversal
filters using their Rayleigh wave and LSAW were
improved 1)-3). However, in case of the resonator devices
such as a double mode SAW resonator filter (DMS) anda ladder filter, it is important to flatten the SiO2 surface
to obtain good frequency characteristics. The LSAW andRayleigh wave on flattened SiO2 film/high density metalelectrode/LiTaO3 or LiNbO3 with excellent TCF wereapplied to SAW duplexers composed of ladder filters 4)-7)
Therefore, depositing the SiO2 film onto the substratewith negative TCF and flatting its substrate are effective
to improve TCF.
The authors previously applied this flattened SiO2
film/high density metal electrode/36º-48ºY·X-LiTaO3
substrate to the DMS that requires a narrow pass band
and a sharp attenuation for RF range, for instance,“MediaFLOTM,“ which is developed by Qualcomm. Inc.
or “Terrestrial Mobile Multimedia Broadcasting (TMMB), which is one of the mobile TV system candidates
in China market.8) The report was mainly focused on
optimizing substrate material to obtain best value of thecoupling factor (k2) and nearly zero TCF. In this report,
filter design on the substrate will be discussed. By
modifying the filter design, shape factor of SAW
resonator filter is improved.

coefficients and coupling factors of Al/36ºY·X-LiTaO3
and flattened SiO2/high density metal electrode/36ºY·XLiTaO3, respectively. The data was calculated by Finite
Element Method (FEM) including thickness (0.25λ) andshapes of electrode and SiO2 (0.05λ). Where λ is wave
length. In case of the filter in Fig. 1, the Al electrode
thickness is 0.04λ to satisfy both enough reflection
coefficient and small coupling factor to realize narrow
bandwidth. The reflection coefficient and the bandwidthof stopband are slightly small of 0.05 (• mark in Fig. 3)
and 0.03, respectively, and it results in the transversal
response. Therefore, it is difficult to design a narrow
band pass filter by Al/LiTaO3 without any transversal
responses. On the other hand, the bandwidth of the
stopband is 0.06 to 0.07 by the flattened SiO2/highdensity metal electrode/36ºY·X-LiTaO3 with theelectrode thickness ( ○ marks in Fig.3) where thereflection coefficient is doubled from the filter in Fig. 1.
The stop bandwidth is sufficient to suppress thetransversal responses. Moreover, SiO2 film has the meritsof not only improving TCF but also being the coupling
factor smaller to realize narrow band, so that thisstructure is suitable to design a narrow band pass filter.
Then a filter is designed by this structure.

Insertionloss[dB][dB]
Magnitude

1. Background-12
Transversal

response

719
Frequency [MHz]

-16
759

Fig. 1 Frequency characteristic of RF filter withconventional Al/36º-48ºY·X-LiTaO3 substrate.
Each DMS filter consists of two IDTs and two
reflectors as shown in Fig. 2, where λ is about 5µm, theaperture is about 16λ, the gap between IDTs is about
0.5λ, the number of pairs of the IDT is around 20, thenumber of fingers of the reflectors is around 50, and themetallization ratio is about 0.6. The thickness of SiO2 is
0.27λ. The total size of SAW package is 1.4 × 1.1 × 0.6
mm by using Chip Size Package (CSP) structure.
By using the above-mentioned structure, thetransversal response can be suppressed as shown by solidline in Fig.6. However, some of the application requires
more severe specification for attenuation. In order toimprove the attenuation slope more sharply, the authors
modified the IDT design of the DMS filter to improve
the shape factor.

in

out

optimized it and found a certain case that was possible toimprove the attenuation slope without performancedegradation. It is achieved by putting a couple ofadjacent fingers near the gap of two IDTs onto the same
direction and same electric potential. The phase of some
SAW is inverted around these fingers (phase inverse
design) and it results in the sharper attenuation slope asshown in Fig. 5 (b). Fig. 6 shows the comparison
between normal design (solid line) and phase inverse
design (broken line). The shape factor has been
improved.
(a)(b)

Fig. 2: Composition of RF filter composed of DMS.
Metal
SiO2

0.4

Pt

W

Fig. 5: IDT structure - (a)Normal design, (b)Phase
inverse design.

LT

Au

0.3

Ta
0.2

Cu

Al

0.1
0.0
0.00

LT

0.02 λ0.04 λ0.06 λ0.08 λ0.10 λMetal thickness

Fig. 3 Calculated reflection coefficients on flattened
SiO2/various electrode/36ºY·X-LiTaO3 and Al/36º Y·XLiTaO3 as function of electrode thickness.
0.12

Coupling factor:k

2

0.10

SiO2=0.25λ

Al
LT

Ta

0.06
0.04

Pt W

Au

0

-20

-4

-40

-8

-60

-12

-80

-16

679

719
Frequency [MHz]759

Fig. 6: Frequency characteristic of RF filter withflattened SiO2 film/high density metal electrode/36º48ºY·X-LiTaO3 substrate. (broken line: Phase inverse
design, solid line: Normal design)Metal

The optimizing filter design results in improving shapefactor of SAW resonator filter. This design is suitable forflattened SiO2 film/high density metal electrode/36º48ºY·X-LiTaO3 substrate with a narrow pass band and a
sharp attenuation.

SiO2

0.02

LT

0.00
0.00

0

3. Conclusion
Cu Al

0.08

Insertionloss[dB][dB]
Magnitude

Reflection Coefficient

SiO2=0.25λ

Magnitude
Insertionloss[dB][dB]

0.5

0.02 λ0.04 λ0.06 λReferences

0.08 λ0.10 λMetal thickness

Fig. 4 Calculated coupling factors on flattened
SiO2/various electrode/36ºY·X-LiTaO3 and Al/36º Y·XLiTaO3 as function of electrode thickness.

2.2 Improvement of shape factor
The fingers of normal IDT is designed alternately on asubstrate as shown in Fig. 5(a). If the order is broken, theSAW resonance is not excited so well and the filter
performance is degraded. But when the disadvantage
effect from disorder is quite small, there are somepossibilities to modify IDT finger order. The authors

1. T. E. Parker and H. Wichansky: Proc. IEEE Ultrason. Symp.,(1974)5031.
2. T. E. Parker and M. B. Schulz: Proc. IEEE US. Symp., (1975) 295.
3. K. Iwasaki, K. Yamanouchi, and K. Shibayama: Tech. Rep. of
IEICE of Jpn., US-77-43 (1977)37 [in Japanese].
4. M. Kadota, T. Nakao, N. Taniguchi, E. Takata, M. Mimura, K.
Nishiyama, T. Hada, and T. Komura: Proc. of IEEE Ultrason.
Symp., (2004) 1970.
5. M. Kadota, T. Nakao, N. Taniguchi, E. Takata, M. Mimura, K.
Nishiyama, T. Hada, and T. Komura: Jpn. J. Appl. Phys. 44 (2005)
4527.
6. T. Nakao, M. Kadota, K. Nishiyama, Y. Nakai, D. Yamamoto, Y.
Ishiura, T. Komura, N. Takata, and R. Kita: Jpn. J. Appl. Phys. 46,
Part I, 7B (2007) 4760.
7. M. Kadota, T. Nakao, K. Nishiyama, Y. Nakai, D. Yamamoto, Y.
Ishiura, T. Komura, N. Takata, and R. Kita: Jpn. J. Appl. Phys. 46,
Part I, 7B (2007) 4714.
8. T. Murata, M. Kadota, T. Nakao, and K. Matsuda: Jpn. J. Appl.
Phys. 47 (2008) 4101.

1P5-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 133- 134
11-13 November, 2008

A Full-Wave Analysis of Surface Acoustic Waves
Propagating on a SiO2 Overlay/Metal Grating/Rotated
YX-LiNbO3 Substrate Structure

1. Introduction
The authors have recently reported a full wave
analysis of piezoelectric boundary acoustic waves(PBAWs) [1] propagating in a semi-infinite SiO2
overlay/Cu grating/rotated YX-LiNbO3 (LN)
substrate structure [2]. In this paper, instead of thesemi-infinite SiO2 overlay, we make an analysis of
SiO2 overlay of finite thickness/metal grating/rotated YX-LN substrate structure. The influence ofthickness and surface topology of the SiO2 overlay
upon acoustic wave excitation and propagation
characteristics are discussed.
2. Simulation and Analysis
1. Simulation Steps:
The simulation is carried out for two types ofstructures shown in Fig. 1 and Fig. 2, where the
YX-LN substrate is of semi-infinite. For metal
grating materials, either Cu or Al grating is assumed.
For the Cu and Al gratings, the thickness is fixed at
0.2p [2] and 0.16p [3], respectively. Different fromref [2], the SiO2 thickness is assumed to be finite in
Figs. 1 and 2.
Using the software – SYNCO, we calculated
Y (ω) of an infinitely long metal IDT sandwiched in
between the SiO2 and YX–LN as a function of therelative frequency fp/VB (VB = 4,752 m/s is the
fast-shear BAW velocity in LN). Fig. 3 shows theresult for the flattened-SiO2 overlay structure whereh2 = 3.2p with the Cu grating. It is seen that there
propagate several modes. Some are caused bythickness resonance modes in the SiO2 overlay,
some by Rayleigh- and SH-type acoustic waves.

^
Relative admittance Y/ωC

Yiliu Wang†‡, Ken-ya Hashimoto, Tatsuya Omori and Masatsune Yamaguchi (Graduate
School of Engineering, Chiba University)
40
30
20
10

Im
Re

0
-10
-20
-30
-40
0.3

0.35

0.4

0.5

0.45

Relative frequency, fp/VB
Fig. 3 Input admittance of infinitely-long Cu IDT

We calculated relative admittance for various
SiO2 thickness (0<h2/2p<2) to help distinguish themodes. As shown in Fig. 3, the modes whose
relative frequency is less than 0.43 are non-leaky,because their Re[ Y /ωC] is zero. From Fig. 3, we
can get the resonance and anti-resonance frequency
of a certain mode (fr and fa). The electro-mechanicalcoupling factor of this mode can be evaluated by
the difference of fr and fa. Besides the flattened-SiO2
overlay structure, we also make an analysis of thecontrolled shape SiO2 controlled shape SiO2 overlay
structure, where SiO2 thickness h2/2p varies from 0
to 2, with h1 and h3 being fixed at 0.2p. On the other
hand, for the Al grating, the thickness h2/2p ischanged from 0 to 2, with h1 and h3 being fixed at
0.16p.
2. Simulation Results and Analysis
Fig. 4 shows the change in the effective
velocities (Vr=2frp, Va=2fap) with the SiO2 thickness
for the controlled shape SiO2 overlay structureusing the Cu grating, where V1 (=4,031m/s)
represents the slow shear bulk acoustic wave
velocity in LN. V2 (=3,766 m/s) is for the shear bulk
acoustic wave velocity in SiO2, which determines

h3

SiO2

h2
Metal

h1

YX-LN

Fig. 1 Controlled shape SiO2 overlay/metal grating/rotated YX-LN structure
Metal

SiO2

h2
Metal

h1

YX-LN

4.6

Effective velocity [km/s]

Metal

4.4
4.2
4
3.8

V2

3.6
3.4
3.2
3
0

Fig. 2 Flattened-SiO2 overlay/metal grating/rotated YX-LN structure

V1

0.5

1

1.5

2

SiO2 thickness h2/2p
Fig. 4 Variation of the effective velocities of acoustic
waves with h2/2p (Controlled: Cu h1=h3=0.2 p)

Effective velocity [km/s]

whether the acoustic wave is leaky or not; when
V<V2, it is non-leaky. Otherwise, it is leaky. In the
figure, “□” shows Vr and Va of the SH-type PBAW,
while the dotted lines are for those of theRayleigh-type PBAW. Their effective velocities
become unchanged when SiO2 thickness is large,
4.6
4.4
4.2
4

V1

3.8

V2

3.6
3.4
3.2
3
0

0.5

1

1.5

2

0.5

1

1.5

2

Effective velocity [km/s]

SiO2 thickness h2/2p
Fig. 5 Variation of the effective velocities of
acoustic waves with h2/2p (Flattened: Cu h1=0.2 p)

4.5

V1

4

V2

3.

3.5
0

SiO2 overlay. The line with “+” represent theSH-type SAW, while the dash-dotted lines are for
the Rayleigh-type SAW on the SiO2 top surface.
The sparse dotted points are for the Rayleigh-type
PBAW. When 0.8<h2/2p<1.2, it seems that theRayleigh-type PBAW couples with different modes.
This behaviour is not yet clearly understood whichbranch corresponds to which mode. From Figs. 4
and 5, it is suggested for the implementation ofpotential PBAW devices, the SiO2 thickness h2/2p
should be made relatively large (say, greater than
1.9), so that the Rayleigh-type SAW on the top
surface of the SiO2 overlay may be suppressed. The
thickness resonance modes (shown as “o” markers)
in the SiO2 overlay could be suppressed bysand-blasting the SiO2 surface.
In the controlled shape SiO2 structure, the Al
grating is also applied to the comparison with theCu grating. The results are shown in Fig. 6.
Similarly, “o” marks the thickness resonance modes
in SiO2. Sand-blasting is needed for the SiO2
surface. The lines with “+” are for the SH-type
SAW, whilst the dash-dotted lines are for theRayleigh-type SAW. Fig. 6 suggests that SH-type
SAW may be effective in device implementation. If
the SiO2 thickness h2/2p is relatively small (i.e., lessthan 0.5), the Rayleigh-type SAW is barely excited.
From Fig. 6, therefore, the SiO2 thickness of
0<h2/2p<0.5 is of interest, which agrees fairly wellwith the result shown in ref [3].

SiO2 thickness h2/2p
Fig. 6 Variation of the effective velocities of acoustic
waves with h2/2p (Controlled: Al h1=h3=0.16 p)

with coupling factor being kept almost the same.
The results definitely reveal that there propagate
two kinds of PBAWs in the controlled shape SiO2
overlay structure. The mark “o” represents the
thickness resonance modes in the SiO2 overlay,
which could be suppressed by sand-blasting the
SiO2 surface. The lines with “+” represent theSH-type surface acoustic wave (SAW) propagatingon the SiO2 top surface. It is crystal clear that thismode vanishes with an increase in the SiO2
thickness (h2/2p>1). The dash-dotted lines are for
the Rayleigh-type SAW, coupling factor of which
also decreases with an increase in h2. This suggeststhat h2/2p should be greater than 1 in device
implementation.
For comparison with the controlled shape SiO2
overlay structure, Fig. 5 shows the result for theflattened-SiO2 structure. Similar to Fig. 4, there
propagate PBAWs when the SiO2 thickness h2/2p isfrom 1 to 2. The mark “o” on the upper right
represents the thickness resonance modes in theConclusion

In this paper, numerical analysis on finite SiO2
overlay/metal grating/rotated YX-LN structure wasconducted and results were analysed in details. Twotypes of structures are compared with each other tocheck the influence of thickness and surface
topology of the SiO2 overlay upon acoustic waves
excitation and propagation characteristics. For
metal gratings, Cu and Al are applied. The results
showed that there propagate PBAWs in both
structures with Cu as the grating, but not with the
Al grating.
Acknowledgment
This work was partly supported by TriQuint
Semiconductor, Inc. It is our pleasure to thank Dr.
Benjamin P. Abbott of TriQuint for his suggestions
and discussion.
References
1. H. Kando, et al：Jpn. J. Appl. Phys. 45 (2006)
4651. Or H. Kando, et al：Proc. IEEE UltrasonicSymp., (2006) 188.
2. Y. Wang, et al：Proc. IEEE Freq. Contr. Symp.,(2008) [to be published].
3. H. Nakamura, et al：Proc. IEEE Ultrasonic Symp.,(2007) 488. Or H. Nakamura, et al：Jpn. J. Appl.
Phys. 47 (2008) 4052~4055.

1P5-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 135- 136
11-13 November, 2008

Interpolation Technique for Fast Analysis of SAW and
Lamb Wave Devices
Jan H. Kuypers‡ and Albert P. Pisano(Berkeley Sensor & Actuator Center, University of California at Berkeley)

1. Introduction
The development of high performanceacoustic devices for RF filters and sensors requires
the precise simulation for the design and analysis.
The design procedure generally consists of running
iterations on a given layout to achieve given filteror sensor specifications. In order to obtain an
optimization in a reasonable time the computation
speed is very important. Increasing the computation
power and optimization of the program code areuseful, but generally not sufficient. Very often thecomplexity of the simulation or the number of
output points are reduced to speed up thecomputation, both at the cost of sacrificing
accuracy of the simulation output.
2. Background
Modern acoustic device simulation is
performed in the frequency domain, as various
input parameters are frequency dependent, i.e.
phase velocity, mass loading, propagation loss,
electrode resistivity, etc. Very often the frequency
spacing for the simulation has to be chosen to bevery small, in order to obtain an accurate estimationof high Q resonators and reflective SAW delay line
sensors [1]. Especially for the wideband simulationof high Q resonators (and filters) the correct
estimation of impedance at series andanti-resonance requires a very fine frequency
discretization. In case of a time domain analysis
based on a frequency domain simulation andsubsequent FFT, as used for time-gating procedures
and reflective SAW delay line sensors, requires ahigh frequency discretization in order to be able toresolve long enough time delays in the time domain.
Therefore, it is highly desirable to find a methodthat reduces the number of points to be simulated,but at the same time does not affect the accuracy ofthe simulation output.
2. Interpolation TechniqueIn this paper we present an interpolation
technique that reduces the number of frequencies atwhich the device has to be simulated, with aminimum effect on the accuracy of the output.
Obviously, simply reducing the number of
frequencies in the simulation and interpolating thedirect output does not yield a good estimate of theFig. 1 Simulated impedance of a Lamb wave resonatoron AlN using different interpolation schemes.

resonator or filter. Fitting an equivalent circuit to
the supporting points and using this to increase thefrequency resolution defeats the purpose of ageneral simulation, as the accuracy of the output is
now determined by how well the chosen circuit fits
the actual device under consideration.
The P-Matrix and K-Matrix Model [2, 3] areboth based on deriving nine Kij entries of (3×3)
matrices representing single electrode cells.
Examining the frequency dependence of these
entries reveals that all coefficients Kij if separated
into real and imaginary part are continuousfunctions and are easily fitted by higher orderpolynomials and therefore easily interpolated.
Phase jumps in the transmission coefficients K12
and K21 are removed by multiplying with the sign ofIm{K11}. The key is to perform the interpolation ona level, where no singularities exist. As soon as the
single electrode cells are cascaded the interaction of
the electrodes causes singularities, which cannot beinterpolated in any accurate fashion.

3. Results

4. Conclusion

For this study we computed the impedance ofa Lamb wave resonator on a 1 μm thick aluminum
nitride plate with bottom metallization using asingle electrode design with 21 electrodes,
λ = 25 μm, and acoustic aperture of 100 μm. The
results are shown in Fig. 1. Details of the K-Model
simulation of Lamb wave resonators are given
in [4]. The first curve in Fig. 1 refers to abrute-force simulation of 1000 points. The secondcase is for a reduced computation of using only 40
points, which leads to a very poor estimation of theresonator around resonance and anti-resonance. By
using the proposed interpolation technique using
only 40 computed points the accuracy demonstrated
with the third plot is obtained, which is almost
identical to the original brute force result. Even
using only ten points leads to a very goodprediction of the resonator.
The frequency dependence of the Kij entries
for the brute force case and the interpolation basedon only ten points for an edge electrode are shownin Fig. 2. The edge-electrode case is the mostchallenging, as edge effects lead to a stronger
frequency dependence and require a higher orderpolynomial fit than for a center electrode. The
polynomial order has to be chosen according to thenumber of simulation points or might otherwise
cause errors in fitting. The only inaccuracy of theinterpolation is the signature swing of the Kij related
to the end effects and electrode geometry [5].

We have proposed an interpolation schemethat can be applied to the P-Matrix and K-Matrix
model and significantly reduces the computation
time. In the presented example the numerous
spurious resonances observed in Lamb wave
resonators with low number of electrodes are well
predicted by the simulation using this interpolation
technique, although the device was only simulated
at ten frequencies points.
Acknowledgment
This work was supported by the DARPA
M/NEMS
S&T
Fundamentals
award(HR0011-06-1-0041) under the DARPA Center for
Micro/Nano Scaling-Induced Physics (MiNaSIP).
References
1. J. H. Kuypers, L. M. Reindl, S. Tanaka andM. Esashi, IEEE Trans. Ultrason., Ferroelect.,Freq. Contr., 55, (2008), 1640-1652.
2. C. W. Ruppel, W. Ruile, G. Scholl, K. Wagner,and O. Männer, Proc. IEEE Ultrason. Symp.
1994, 313-324.
3. J. H. Kuypers, D. A. Eisele, L. M. Reindl, Proc.
IEEE Ultrason. Symp. 2005, 1550-1555.
4. J. H. Kuypers, A. P. Pisano, to be presented atIEEE Ultrason. Symp. 2008.
5. J. H. Kuypers, Ph.D. thesis, Tohoku University(2007), 80-81.

1P5-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 137- 138
11-13 November, 2008

High Frequency Lamb Wave Device of LiNbO3 Thin
Film
LiNbO3 薄膜を用いた高周波ラム波デバイス
Michio Kadota, Takashi Ogami†, Kansho Yamamoto, Yasuhiro Negoro, and Hikari
Tochishita (Murata Mfg. Co., Ltd.)
門田道雄, 小上貴史, 山本観照, 根来泰宏, 栃下光（村田製作所）

2. Phase Velocities of Plate Waves

Substrates for surface acoustic wave (SAW)
devices doing currently a important role for handy
telephone have a low velocity as about 4,000 m/s,
so it is considered that it is difficult to apply for ahigher frequency device. The Lamb wave device
can be operated at a high frequency. The waves
propagating in a thin plate are called the platewaves, which are classfied Lamb wave and Shear
Horizontal (SH) wave according to direction ofthese displacements. The plate waves can be excitedby interdigital transducer (IDT). The design method
for SAW device can be also applied for the platewave devices. As the devices using plate waves, theQuartz single crystal1, ZnO-film/pyrex-glass
composite structure2, AlN-film/Si structure3,
LiNbO3 thin single crystal plate4 and LiTaO3 thinsingle crystal plate5 have been reported. The
reported frequencies are lower than 600MHz in the
Quartz single crystal1, 300 MHz in ZnO-film/pyrexglass composite structure2 and 100 MHz in AlNfilm/Si structure3. In addition, these materials havea small electromechanical coupling factor, andtherefore can’t apply the devices required wideband. On the other hand, the reported frequencies in
the plate wave devices using LiNbO3 and LiTaO3
single crystal plate are lower than 100 MHz4,5, butthese devices have a large electromechanicalcoupling factor which realizes wide band. It isdifficult to make very thin plate of LiNbO3 or
LiTaO3 crystals, though A1 mode of Lamb wave in
the Z-cut LiNbO3 or LiTaO3 has a high phasevelocity and a high coupling factor. If a highlyorientated thin film can be realized, a highfrequency such as 5 GHz and wide band device
could be realized.
In this time, authors have tried to realize thehigh frequency device by using an anti-symmetricA1 mode of Lamb wave propagating in Z-X thin
LiNbO3 film having high velocity and highelectromechanical coupling factor. As the result, wehave realized a 4.5 GHz high frequency Lamb wave
resonator composed of thin LiNbO3 epitaxial
film/air-gap/substrate deposited chemical vapor
deposition method (CVD).

Figure 1 shows the calculated phase velocitiesof plate waves propagating in Z-cut thin LiNbO3
plate along X-axis as a function of plate thickness6.
A1 mode of Lamb wave has high velocity over
10,000 m/s, when the LiNbO3 plate thickness isthinner than 0.2 λ ( λ ： wavelength). Finite
Element Method (FEM) was used in thiscalculation.
Phase Velocity [m/s]

1. Introduction

20000
15000

A1

10000

S0

5000
SH0

0

ogami@murata.co.jp

0.2

0.4

0.6

0.8

1

LiNbO3 Thickness[λ]Fig. 1 Calculated phase velocities of plate waves
as a function of LiNbO3 thickness

3. Device Structure
To make air-gap type membrane7 and obtainhigh orientated LiNbO3 film, the buffer layer has
been grown on a substrate. The thin LiNbO3 filmwith thickness of about 480 nm has been depositedon the buffer layer under the condition of the heatedsubstrate temperature of 600 to 700 degrees. The
deposition rate was 12 nm/minite. After the IDT has
been fablicated, the air gap has been made byremove the buffer layer. Figure 2 (a) and (b) show ameasured rocking curve and a pole figure of thethin LiNbO3 film, which show good c-axis
orientated epitaxial twin film because of narrow full
width of half maximum (FWHM) of 0.2 degrees
and 6 spots in the pole figure.
Intensity[cps]100000
10000
1000
100
10
18

19

20

21

ω[deg.](a)------------------------------------------------------------

A0

0

(b)

Fig. 2 (a) Measured rocking curve and (b) pole
figure of thin LiNbO3 film with X-Ray Deffraction

Membrane

ＩＤＴ

A0

1000
100
10
1
0

Air Gap

Base Wefa(a)

Etching Hole2
4
6
Frequency[GHz]Phase[deg.]

LiNbO3 thin film

90
60
30
0
-30
-60
-90

A1

8

Fig. 4
Measured impedance and phasecharacteristics of 1-port resonator (wide range)(b)

Fig. 3 Device structure (a) side view and (b) Top
view

Thickness of the thin LiNbO3 film is 0.15λ andAl-electrode thickness is 0.03λ, which the IDT
wavelength λ is 3.2 μm. 1-port resonator has
aperture of 15λ and 60 finger pairs. Figure 4
shows the measured impedance and phasecharacteristics. A response seen at 4 to 5 GHz is A1
mode of Lamb wave, and that seen at 0.5 GHz is A0
mode one as a result of comparison with simulation.
SH0 mode, which should be excited at 1 to 1.5 GHz
in simulation result, is not excited because of thetwin crystal effect6. Figure 5 shows the measured
impedance and the phase characteristics around theA1 mode of Lamb wave response at narrow range.
The A1 mode of Lamb wave has a high resonant
frequency of about 4.5 GHz, which correspond highphase velocity of 14,000 m/s, and large impedance
ratio of 52dB. Where the impedance ratio is 20×
log10(anti-resonant impedance/resonant impedance).
The mechanical quality factor8 at resonant
frequency is about 170, and that at anti-resonant
frequency is about 90. As a result of fitthing,electromechanical coupling factor k2 has been
evaluated about 18 %, which is 0.8 times oftheoretical one. It is considered that quality of thethin LiNbO3 film deposited by CVD is little inferior
to LiNbO3 single crystal.
5. Conclusion
Authors have tried to realize the high frequency
device by using Lamb wave propagating on Z-X
thin LiNbO3 film deposited by CVD having highvelocity and high electromechanical coupling factor.
As the result, we have realized a 4.5 GHz highfrequency Lamb wave resonator with high velocity
of 14,000 m/s, large impedance ratio of 52dB, andwide bandwidth of 7.2 % composed of thin LiNbO3
epitaxial film/air-gap/substrate.

Impedance[Ω]4. Propaties of 1-port resonator

10000

90
60
30
0
-30
-60
-90

1000
100
10
1
4

4.4
4.8
Frequency[GHz]Phase[deg.]

IDT

10000
Impedance[Ω]Figure 3 (a) and (b) show side view and top
view of a fabricated Lamb wave device,respectively. The membrane with size of 200 μm
squares has been warped, so interference fringes
have been seen.

5.2

Fig. 5
Measured impedance and phasecharacteristics near A1 mode of Lamb wave
response( narrow range)

References
1. Y.Nakagawa, S.Tanaka and S.Kakio: Jpn. J.
Appl. Phys. 42 (2003) 3086.
2. A.Tanaka, M.Koike, F.Saito, K.Hashimoto and
M.Yamaguchi: Technical Report of IEICE Japan
US91-89 (1992) [in Japanese]
3. N.Tirole, A.Choujaa, D.Hauden, G.Martin,
P.Blind, M.Froelicher, J.C.Pommier andA.Cachard: Proc. IEEE Ultrason. Symp. (1993)
371.
4. K.Mizutani and K.Toda: Trans. IECE Japan J68A (1985) 496. [in Japanese]
5. K.Toda and K.Mizutani: Trans. IEICE Japan
J71-A (1988) 1225. [in Japanese]
6. M.Kadota, T.Ogami, K.Yamamoto, Y.Negoro
and H.Tochishita: EM Symp. (2008) 69. [inJapanese].
7. H.Satoh, H.Suzuki, C.Takahashi, C.Narahara
and Y.Ebata: Proc. IEEE Ultrason. Symp. (1987)
363.
8. K.Hashimoto: An Introduction to Simulation
Technique for Surface Acoustic Wave Device(1997) 140. [in Japanese]

1P5-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 139- 140
11-13 November, 2008

A Basic Study on Face to Face Bonded SAW Devices
表面張り合わせによる SAW 素子の基礎検討
Takanori Yamazaki, Keishin Koh and Kohji Hohkawa (Kanagawa Institute ofTechnology)
山崎貴紀

黄啓新

宝川幸司 （神工大 工学部）

Small space gap area

1. Introduction
Many reports on packaging of SAW devices havebeen reported so far (1) – (3). For packaging SAW
devices, we must form capping structure to cover
the surface of the SAW propagating substrate.
Sometimes, these capping structures effect on SAW
characteristics caused by many effects, such as
inherent stress, temperature dependent variation on
SAW propagation characteristics and aging. These
problems could be simply improved, if we would
use the same substrate with SAW substrate as the
capping material of the device. In this situation, we
can also use capping structure as the SAW substrate.
If we would form the structure of the packaging
close enough to couple with each other, we could
produce many new functional device using
coupling modes.
In this paper, we report a simple coupled device
using face to face bonded structure.
2. Face to Face Bonded SAW (FFB) device
As the first device, we introduce the simplest
face to face bonding (FFB) device structure, shownin Fig. 1. Most SAW devices have IDT finger
electrodes with much wider overlapping length thanthat required for avoiding insertion loss, due tobeam spreading, which causes plane wave limit ofpropagation path length. If we connect in parallel
two devices whose overlap length is a half size ofthat of the original device, they could produce
almost the same response as that of original device.
The device size with half overlapping length isslightly larger than the half size of original device
due to increase in terminal electrodes. However,total cost of substrate would not be increased,because smaller chip size enables to reduce
thickness of the substrate.

Substrate 1＋－＋－＋－＋－＋－＋－

IDT

Substrate 2a) Fusion bonded

Bonded by adhesive post materialb) Adhesive bonded

Inserted elastic material for layerc) Fill with liquid

Movable positiond) Variable device
Fig. 2 FFB devices under consideration
From simple device structures shown in Fig. 2, itis clear that the FFB device is one of waveguide
coupled device, similar to the MSC devices(4), when
the separation of the surfaces of two propagation
path is closed. It is clear that the same functional
devices as that of MSC devices could be formed.
On the other hand, if the spacing of two substrates
is designed to be relatively large, it could be a
packaging structure with relatively highperformance, as discussed in the following section.

3. Fabrication process of FFB SAW device

Original device

Half-size device

FFB

Fig. 1 FFB device-----------------------------------------------------------hk-yama@ele.kanagawa-it.ac.jp

There are several device fabrication methods
depending on the function of the device. Fig. 3
illustrates typical process step for FFB-SAW device.
In these process steps, difficulty exists how to dicebonded wafers into multiple chips, maintaining
electrical lead line connection to the external space.
This is especially difficult for the mode coupleddevice which utilizes face to face coupled operation

with narrow spacing between substrates. We form
dimple on the substrates surface to make spacing on
the surface edge of counter chip. This process could
be carried out by chemical etching process ormechanical technology such as sand blast milling.

Patterning SAW devices on wafer(IDT, Dimple hall and PAD forming)
Bond wafer with precise alignment(Spacer / Fusion Bonding)

4. Basic Experiment
We fabricated test devices using Quartz substrate
and buried IDT electrode which is formed using dry
etching technology and lithograph technology.
Tab. 1 shows device parameters of test devices. We
investigated boned method using adhesive materials,
such as film resist and water glass (SiO2:Na2O) Fig.
4 shows photograph of test devices. We estimatedbasic characteristics of FFB-SAW devices. Fig. 5
shows measured results. The SAW devices withburied IDT electrode show relatively goodfrequency characteristics. After bonding, there is nochange in the frequency characteristics. We are
studying dependence of frequency characteristics
on bonding conditions.

5. Conclusion

Dicing wafer to line array shape
Bond lead line and socket
Fig. 3 Fabrication process steps
Tab. 1 Device parameters
Substrate
Quartz ST cut
IDT line & space
2μm:2μm
Electrode material
Al thickness 100nm
Overlap. length
178 μmNumber of pairs
100-100 pairs
Dry etching condition CF4:Ar 100Ｗ 5minBonding condition
100℃, 10min 0.05MPa

We proposed a small, low cost and simple
packaging method for SAW device in which two
devices chips with a half overlapping length with an
original device, are bonded in face to face. We
investigated process condition such as adhesivematerials heating method etc. and fabricated test
devices. The basic experiments results indicate
possibility of FFB technology for realizing coupleddevices.
Acknowledgment
We would like to thank Mr. Okitsu and Mr.
Oshiyama for their contribution on the process. This
work is partially supported by the fund from
Education Culture, Sports, Science and Technology.
References
1. M. Goetz and C. Jones, Proceeding of Electronics
manufacturing technology Symposium, 2002, pp.
63-69.
2. O. Ikata, Y. Kaneda, S. Ono, K. Sakinada, O.
Kawachi, Y. Tanimoto, Third International
Symposium on Acoustic Wave devices for Future
Communication System CD-ROM, 2007
3. K. Koh, T. Yamasaki, and K. Hohkawa,
Proceedings of 2007 IEEE UltrasonicSymposium, （CD media）, pp.1890-1893, 2007.
4. O. Kawachi, K. Sakinada, Y. Kaneda and S. Ono,
Proceeding IEEE Ultrasonic Symposium, 2006,
pp. 2289-2292.
5. F. G. Marshall, C.O. Newton and H. I. S. Paige,
IEEE Trans., MTT 21, PP.195-205 (1973)

Fig. 4 Photograph of test devices
I.B.[dB]
-40

-40

-60

-60

-80

-80

Original[dB]
FFB[dB]
-100
310

320
Frequency[MHz]

-100
330

Fig. 5 Frequency characteristics of
SAW devices after face to facebonding.

1P5-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 141- 142
11-13 November, 2008

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1P5-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 143- 144
11-13 November, 2008

Leaky-SAW Properties on Reverse-Proton-Exchanged LiNbO3
逆プロトン交換LiNbO3基板上のリーキー表面波伝搬特性
Hidenori Shimizu‡, Shoji Kakio and Yasuhiko Nakagawa (Univ. of Yamanashi)
清水秀徳‡，垣尾省司，中川恭彦 （山梨大院・医工）

Introduction

2.

TheoryThe substrate structure after RPE process has afour-layered structure as shown in Fig. 1(a). For
convenient calculation, a three-layered structure of
air/bulk LN/softened LN was assumed as shown in
Fig. 1(b). The elastic constants c’ij of the softened
LN were expressed by Acij, where c’ij are bulk
values and A is a parameter. The elastic constant of
the PE layer are approximately 60% of those ofbulk LN. The elastic constant is considered to be
recovered by annealing effect during the PRE
process. Therefore, the parameter A was set to beranged from 0.6 to 1.0.
Figure 2 shows the calculated phase velocity as afunction of the rotation angle from Y-axis when thenormalized depth d/λ of the bulk LN layer was
fixed to be 0.2 λ, for (a) the free and (b) metallized
surface cases. The corresponding attenuations areshown in Fig. 3.
-------------------------------------------------------------g08me015@yamanashi.ac.jp

Bulk LN Layer (cij )RPE Layer

Buried PE Layer

Softened LN Substrate(c' ij = Acij )LN Substrate(a) RPE LN(b) Analytical modelFig. 1 Structures of RPE LN and analytical model.

According to the decrease of the elastic constantof the substrate, it seems that the range of rotation
angles giving zero attenuation markedly expanded
for free surface [Fig. 3(a)]. It appears in a wide
range of -30˚~95˚ at A=0.6. The phase velocity
decreases monotonously with the decrease of theelastic constant [Fig. 2(a)]. The phase velocity of afast shear bulk wave in the softened LN is also
decreased. The range of the rotation angles which
the LSAW phase velocity exceeds that of the bulk
wave expanded. The LSAW solution is not
obtained in this range. However, the attenuation isvanished to zero immediately before the LSAW
phase velocity exceeds that of the bulk wave.
On the other hand, for the metallized surface, theAir/Bulk LN/Softened LN, d/λ =0.2, Free

4800
Phase Velocity (m/s)

Leaky surface acoustic waves (LSAWs) have an
inherent attenuation because LSAWs lose energy bycontinuously radiating the bulk wave into thesubstrate. Because of this property, the cut of thesubstrate with a smaller attenuation is used in the
LSAW device. The authors reported that, in acertain range of rotation angles for rotated Y-X
LiNbO3 (LN), the attenuation can be reduced byforming a proton-exchanged (PE) layer with anelastically soft property on the substrate.1 However,by carrying out the PE process, the piezoelectric
property is nearly eliminated and the coupling
factor K2 is reduced.
On the other hand, reverse proton exchange(RPE) has been proposed as a method of exchangelithium ions and protons on the PE layer to fabricate
buried optical waveguides.2 It can be expected that
the RPE layer with a property similar to that of bulk
LN prevents the degradation of K2 and the buried
PE layer reduces the LSAW attenuation.3
In this study, first, a layered structure of air/bulk
LN/softened LN was assumed for the rotated Y-X
LN and the LSAW attenuation was calculated. Next,
the RPE layer and the buried PE layer were formedon the 41˚ Y-X LN and the LSAW propagation loss
(PL) was measured.

4600
4400
A
: 1.0
: 0.9
: 0.8
: 0.7
: 0.6

4200
4000
Y-cut

3800

-30

Z-cut

0
30
60
90
Rotation Angle from Y-axis θ (° )(a) Free
4600
Phase Velocity (m/s)

1.

Air/Bulk LN/Softened LN, d/λ =0.2, Metallized

4400
4200
4000
3800
Y-cut

3600
-30

A
: 1.0
: 0.9
: 0.8
: 0.7
: 0.6

Z-cut

0
30
60
90
Rotation Angle from Y-axis θ (° )(b) Metallized

Fig. 2 Calculated phase velocity.

1 Air/Bulk LN/Softened LN, d/λ =0.2, Free

40

A
: 1.0
: 0.9
: 0.8
: 0.7
: 0.6

0

10

35
Insertion Loss (dB)

Attenuation (dB/λ )

10

-1

10

-2

10

Y-cut

-30

: Propagation Loss
: Bulk Wave Radiation Loss
: Conversion Loss

25
20
15
10
5

Z-cut

-3

10

30

41° Y-X LN, L=300λ , Free

0

0
30
60
90
Rotation Angle from Y-axis θ (° )Virgin(a) Free(a) Free1 Air/Bulk LN/Softened LN, d/λ =0.2, Metallized

40

A
: 1.0
: 0.9
: 0.8
: 0.7
: 0.6

0

10

-1

10

-2

10

Y-cut

-30

: Propagation Loss
: Bulk Wave Radiation Loss
: Conversion Loss

30
25
20
15
10
5

Z-cut

-3

10

41° Y-X LN, L=300λ , Metallized

35
Insertion Loss (dB)

Attenuation (dB/λ )10

PE2.6h RPE2.5h RPE10h RPE40h

0

0
30
60
90
Rotation Angle from Y-axis θ (° )VirginPE2.6h RPE2.5h RPE10h RPE40h(b) Metallized(b) Metallized

Fig. 3 Calculated attenuation.

Fig. 4 Details of insertion loss of 41˚ Y-X LN sample.

solution exists in the rotation angle range because
the phase velocity is slower than that of the bulk
wave [Fig. 2(b)]. The rotation angle giving zeroattenuation shifts from 64˚ toward 5˚ [Fig 3(b)].

virgin sample to 0.015 dB/λ. The decrease of the
PL for the free surface was also observed. The CL
was increased after the RPE process because the K2
was reduced in above fabricating conditions.

3.

4.

Experiment

A simple delay-line sample with different depthsof the RPE layer was fabricated on 41˚ Y-X LN
substrate. First, the PE layer with a depth of 1.9 μm
was formed by immersing the LN substrate in asolution of benzoic acid (Li 0.1 mol%) at 240˚C for
160 min. Next, the RPE layer was formed byimmersing the PE sample in an equimolar mixtureof LiNO3 -NaNO3-KNO3 at 300˚C for 2.5 h, 10 h,
or 40 h. Finally, interdigital transducers (IDTs) witha period length λ of 20 μm and 8 split-finger pairs
were fabricated on the sample using Al film.
Using a network analyzer, the frequency response
was measured. Figure 4 shows the insertion loss
(IL) for L=300 λ as a histogram. The IL for both
surface cases that increased after the PE process
was recovered by carrying out the RPE process.
Further RPE process increases the value. The PL
was estimated by subtracting the IL with a path
length of 100 λ from that of 300 λ. The values of
the PL, the conversion loss (CL), and the bulk wave
radiation loss are also shown in Fig. 4. The PL for
the metallized surface was decreased by carryingout the RPE process for 10 h from 0.036 dB/λ of aConclusion

The LSAW properties on the rotated Y-X LN
substrate with the RPE layer and the buried PE
layer were investigated. First, a layered structure of
air/bulk LN/softend LN was assumed the LSAW
attenuation was calculated. The rotation angle from
Y-axis giving zero attenuation shifted from 64˚
toward 5˚ for a metallized surface. The range of therotation angles which the LSAW phase velocity
exceeds that of a fast shear bulk wave markedly
expanded in a wide range of -30˚~95˚ for a freesurface while the attenuation was vanished at theseboundaries. Next, the measured PL on 41˚ Y-X LN
was decreased by carrying out RPE process.
We will experimentally apply the layered structure
to a 5˚~15˚ rotated Y-X LN substrate with a large K2.
References
1. S. Kakio et al., IEICE Trans. J80-A (1997) 1830
[in Japanese].
2. J. Olivares and J. M. Cabrera, Appl. Phys. Lett. 62(1993) 2468.
3. M. Maeda, S. Kakio, and Y. Nakagawa, Proc.
USE2007 (2007) 93.

1P5-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 145- 146
11-13 November, 2008

AlGaN/GaN device using buried electrode structure
埋め込み形電極構造を用いた AlGaN/GaN 素子
Yuji Terao, Satoshi Oshiyama, Keishin Koh and Kohji Hohkawa(Kanagawa Institute of Technology.)
寺尾有司

押山聡

黄啓新

宝川幸司 （神工大 工学部）

１．Introduction
AlGaN/GaN film has been expected and used forhigh speed systems such as satellite communication
and ultra high speed optical transmission systems[1]. Focused on its piezoelectric properties, it is also
expected for SAW devices at the same highfrequency range and many research results arereported so far [2-4]. This paper investigates new
surface acoustic wave devices which consist oftransducers having 2 DEG layer electrodes.
There exists a thin 2 DEG layer with relatively
high conductivity in the interface of the
AlGaN/GaN film. Difference of this structure fromconventional transducers with metal electrodes, isthe transparency nature of the conductive layer andexisting of AlGaN laver over it. This structure
would simplify the device fabrication process. In
addition, this structure might have produced a new
functional operation by changing 2 DEG layer as
conductive electrodes.

2. SAW device structures consisting of
2DEG electrodes
It is possible to form many kinds of device
structures for making SAW device consisting of 2
DEG conductive electrodes. Here, we consider
three structures illustrated in Fig. 1.
a) We form this structure by simply etching
AlGaN film layer existing on the space regionof transducer using gas plasma etchingequipment. .
b) We fabricate simply metal space patterns on the
AlGaN/GaN film. The 2 DEG electrodes areformed by applying negative bias potential on it
so that carriers under electrodes may move tothe region of transducer.
c) We form comb shaped AlGaN layer and placegate electrodes to enhance carrier densities in 2
DEG layer corresponding finger electrodes. By
applying positive potential, we can enhancecarrier density of finger electrodes.
oshiyama@ele.kanagawa-it.ac.jp

AlGaN layer etched area

Ohmic Contact

AlGaN
GaN
Al2O3 Suba) AlGaN layer IDT

2DEGb) Suppress by metalc）Metal coverFig. 1 Various type of 2DEG IDT

3. Experimental and result

References

We fabricated test devices with structure as shownin Fig. 1. Table I shows their parameters. The filmwith the layer with AlGaN film thickness of 0.02 μm
correspond the layer used for HEMT. An AlGaN/GaN
film was deposited on a (0001) sapphire substrate bymetal organic chemical vapor deposition, and thealuminum mole fraction of the AlGaN layer was
nominally 0.255. The space area of transducer in
Fig. 1 is formed by using dry etching process. We
formed Aluminum electrode patterns using liftoff
method and also formed Ohmic contact pads
consisting of Ti/Al by heating samples at 800℃, for45s. An example of test devices photograph show in
Fig. 2.
We used microwave probes and a network
analyzer (Anritsu MS4623B) to estimate thefrequency characteristics of test devices. Fig. 3
shows an example of frequency characteristics for atest device. The experimental results of devices
with 2 DEG electrodes, especially devices withthick AlGaN layers, have shown a relatively large
insertion loss due to poor conductivity of films.
These devices seem to be rather pessimistic forpassive device application, such as resonator andfilters. However, when the carrier densities under 2
DEG are increased by DC bias or light induced
method, the filed effect due to SAW could beenhanced and the good frequency characteristics
could be expected. We are now investigating

1. C. Deger, E. Born, H. Angere, O. Ambacher, M.
Stutzmann, J. Hornsteiner: Applied Phyisics.
Letters, 72, (1998) 2400.
2. N. Shigekawa, K. Nishimura, H. Yokoyama andK. Hohkawa: Applied. Phyisics Letters, 87(2005) 084102
3. N. Shigekawa, K. Nishimura, T. Suemitsu, H.
Yokoyama and K. Hohkawa; Applied Phyisics
Letters, 89, (2006) 033.
4. T. Mizusawa, M. Wada, K. Koh, K. Nishimura,
N. Sigekawa, and K. Hohkawa: Proc.
Symposium on Ultrasonic Electronics, 26, (2005)
223.
Table 1. Parameters used for the experiments
Substrate
AlGaN / GaN / Al2O3
Thickness of AlGaN film 0.02 , 0.1, 0.3 μm
Thickness of GaN film
2 μm
IDT line &space
2μm:2μm
Overlap. length
200 μmNumber of pairs
50-50 pairs

GaN
AlGaN

4. Conclusion
We estimated AlGaN/ GaN SAW devices
consisting of 2 DEG layer electrodes. We fabricatedtest devices with various electrodes patterns andestimated basic characteristics. We observed
generation and detection of SAW in AlGaN/GaN
system by electrode of 2 DEG. It is very poor
compared with the metal electrode. But, someresults indicated that AlGaN/GaN system with thisstructure would realize variable SAW devices
operating at high frequency using field modulation.
In enhance preference of the device, we arepreparing higher frequency devices by electron
beam lithograph technology and investigating
optimum electrode structure. We also discusspossibility of application as optical sensor.

Fig. 2 Photograph of test device.
Insertion loss [dB]

-60

-70

-80

0.56

0.57

0.58

Freq. [GHz]Acknowledgment
We would like to thank Mr. Okitsu and Mr.
Oshiyama for their contribution on the process. This
work is partially supported by the fund from
Education Culture, Sports, Science and Technology.

Fig. 3 Frequency characteristics of
AlGaN/GaN SAW device used 2 DEG aselectrodes.

1P5-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 147- 148
11-13 November, 2008

Fabrication of Highly Oriented Ta2O5 Piezoelectric Thin Films
by RF-Magnetron Sputtering
高周波スパッタリング法による高配向Ta2O5圧電薄膜の作製
Takeshi Mitsui‡, Akinori Tsuchiya, Shoji Kakio and Yasuhiko Nakagawa (Univ. of Yamanashi)

三井 剛‡，土屋彰教，垣尾省司，中川恭彦（山梨大院・医工）

1.

For the development of high-performancepiezoelectric devices, such as surface acoustic wave
(SAW) and film bulk acoustic resonator (FBAR)
devices, piezoelectric thin films required to realize
high coupling, high stability, low loss and highfrequency have been widely studied. An X-axisoriented tantalum pentoxide Ta2O5 piezoelectricthin film is a relatively new material developed by
one of the authors, and has features, such as a large
piezoelectric property similar to that of ZnO thinfilms and a high dielectric constant.1,2 Investigations
on the preparation conditions to improve theproperties have been carried out.3-5
On the other hand, the authors reported that, inthe deposition of potassium niobate KNbO3 thinfilms using an RF-magnetron sputtering systemwith a long-throw sputter (LTS) cathode and an
O2-radical source, a high (110)-orientation and asmooth surface were obtained.6
In this paper, the X-axis-oriented Ta2O5 thin films
were deposited on a fused quartz substrate using the
RF-magnetron sputtering system. The degree oforientation and the electromechanical coupling
factor (K2) for the Rayleigh-type SAW were
evaluated.
2.

Process chamber

Introduction

Deposition of Ta2O5 thin film

Figure 1 shows the configuration of the
RF-magnetron sputtering system with long-throw
sputter (LTS) cathodes and the O2-radical source
used for the deposition of the Ta2O5 thin film on a
fused quartz substrate.
The sputtering parameters are shown in Table I.
A metal tantalum target with 50 mm diameter wasused and the distance between the target and thesubstrate was 100 mm. The substrate temperature
TS was varied from 650˚C to 750˚C. The RF power
applied to the cathode and radical source was 150
W. The atmosphere gas flow rate Ar:Ar for the twocathodes with/without the target was 30:3 ccm andthe O2 flow rate for the radical source was varied
from 4 to 10 ccm, while the atmosphere gaspressure was fixed to be 0.75 Pa. The deposition
time was 5 h and the deposition rate ranged from0.54 to 1.73 μm/h.
-----------------------------------------------------------g08me030@yamanashi.ac.jp

10 rpmLoad-lockchamber

Infrared lamp heater

Substrate
T/S=100 mm

O2 radical

TMP

Ta target

TMP

LTS cathode(without target)

LTS cathode
Ar

O2

Ar

Fig. 1 Configuration of RF-magnetron sputtering system.
Table I Sputtering parameters.
Substrate

Fused quartz

Substrate temperature (˚C)

650 ~ 750

Gas flow rate, Ar : Ar : O2 (ccm)

30 : 3 : 4 ~ 10

Gas pressure (Pa)

0.75

Target-substrate distance T/S (mm)100Target power (W)150

O2-radical power (W)

0 ~ 150

Deposition time (h)5Film thickness (μm)

2.70 ~ 8.65

Deposition rate (μm/h)

0.54 ~ 1.73

3.

Evaluation of Ta2O5 thin film

The degree of orientation was evaluated from
X-ray diffraction (XRD) patterns. Figure 2 shows
XRD patterns for the O2-radical power of (a) 150 W
and (b) 0 W when TS and the O2 flow rate were
700˚C and 6 ccm, respectively. As can be seen fromthese XRD patterns, it was found that supplying the
RF power to the O2-radical source markedly
activated the preferred (200)-axis orientation.
The degree of orientation was sensitive tochanges of TS and the O2 flow rate. The full width at
half maximum of the peak at 750˚C decreased to ahalf value of that at 700˚C. However, the peakalmost disappeared at 650˚C. Moreover, when theO2 flow rate was 10 ccm, the orientation similar tothat for 6 ccm was obtained. On the other hand,when the O2 flow rate was 4 ccm, several spurious
peaks were observed in the XRD pattern and apolycrystalline thin film was deposited.

0

IDT : λ =20 μ m, N=30, L=100 λMinimum I.L. = 26.1 dB

Insertion Loss (dB)

700° C, O 2: 6 ccm(200)

X-ray Intensity (a.u.)

700° C, O 2: 150 W, 10 ccm, h/λ =0.135(400)(a) O 2-radical power : 150W

20
40
60
80

(b) O 2-radical power : 0W

20

25

30

35

40
45
2 θ (° )

50

55

100
115

60

120

125
130
Frequency (MHz)

135

140

Fig. 3 Frequency response of IDT/Ta2O5 thinfilm/fused quartz sample (c).

Fig. 2 XRD patterns of Ta2O5 thin film deposited by
O2-radical power of (a) 150 W and (b) 0 W.
Table II Measured coupling factor K2.

(a)
(b)
(c)
(d)
(e)

Ts
(˚C)

O2-radical
power (W)

O2
(ccm)

h
(μm)

h/λ

K2
(%)

700
700
700
650
750

150
0
150
150
150

6
6
10
6
6

5.50
2.58*
2.70
3.63
3.43

0.275
0.129
0.135
0.182
0.172

0.12
0.02
0.23
~0
~0

(μm)

*deposition time: 3.5 h

Interdigital transducers (IDTs) with a period
length λ of 20 μm and 30 single-finger pairs were
fabricated on the deposited film using Al film. The
electromechanical coupling factor (K2) for theRayleigh-type SAW was evaluated from themeasured admittance property.
Table II shows the measured K2 corresponding to
the above-mentioned sputtering parameters. Whenthe substrate temperature TS was 700˚C, thepiezoelectric property in the deposited thin film wasobserved. The K2 of the sample (c) with the O2 flowrate of 10 ccm was measured to be 0.23% for thenormalized thickness h/λ of 0.135. This value isabout half of that for the previously obtained
X-axis-oriented Ta2O5 thin film using a DC diodesputtering system.2 On the other hand, the K2 of thesample deposited at 750˚C was negligible small inspite of its high orientation. Therefore, thepiezoelectric property was sensitive to substratetemperature.
Figure 3 shows the measured frequency response
for the sample (c) with the K2 of 0.23%. The
propagation loss was estimated to be approximately
0.05 dB/λ from the minimum insertion loss of 26.1
dB, the conversion loss of 20.3 dB, and the
propagation length of 130 λ.
Figure 4 shows a surface morphology image
obtained by atomic force microscopy (AFM) for the
sample (c). The root-mean-square roughness Rq
was measured to be 9.8 nm over a typical 10 x 10
μm2 region.

Fig. 4 AFM image for Ta2O5 thin film sample (c).

4.

Conclusions

The X-axis-oriented Ta2O5 piezoelectric thinfilms were deposited using an RF-magnetron
sputtering system. Supplying the RF power to theO2-radical source markedly activated thepreferred (200)-axis orientation. When thesubstrate temperature was 700˚C, the coupling
factor K2 was measured to be 0.23% for thenormalized thickness h/λ of 0.135.
Further optimization of sputtering condition
will be investigated to obtain a higher
piezoelectric property.
References
1. Y. Nakagawa and Y. Gomi: Appl. Phys. Lett. 46(1985) 139.
2. Y. Nakagawa and T. Okada: J. Appl. Phys. 68(1990) 556.
3. Y. Nakagawa and T. Igarashi: Jpn. J. Appl. Phys.
41 (2002) 3285.
4. Y. Nakagawa, I. Morita, M. Takahashi and S.
Kakio: Jpn. J. Appl. Phys. 46 (2007) 4441.
5. S. Wu and B. Houng: Proc. Japan-Taiwan
Workshop on Future Frequency Control Devices(2007) 57.
6. S. Kakio, H. Kurosawa, T. Suzuki and Y.
Nakagawa: Jpn. J. Appl. Phys. 47 (2008) 3802.

1P5-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 149- 150
11-13 November, 2008

Variation of SAW velocity and propagation loss by grainboundaries
結晶粒界による薄膜 SAW 速度と損失の変化
Shingo Chida1†, Tomoaki Karaki1, Masatoshi Adachi1,
Makoto Furuhata2, Takamitsu Higuchi2 and Tsukasa Funasaka2(1Toyama Prefectural Univ.; 2SEIKO EPSON CORPORATION)
千田進悟 1†, 唐木智明 1, 安達正利 1, 古畑誠 2, 樋口天光 2, 舩坂司 2(1 富山県立大, 2 セイコーエプソン株式会社)

1. Abstract

4. Calculation of elastic constants

High frequency communication devices including
thin film surface acoustic wave (SAW) filter, film
bulk acoustic resonator (FBAR), as well as microelectromechanical systems (MEMS) use piezoelectric thin films (PZT, LiNbO3, AlN, ZnO) as
actuating elements.
However, sound velocity of polycrystalline piezoelectric films is sometimes different from that
calculated using published single-crystal elastic
constants. There is reason to believe that thatwas caused by grain boundaries. In this work,
elastic constants of thin films were calculated byusing a composite model. In addition, because
complex elastic constants were introduced in thecalculation, propagation loss was evaluated, and agood result was obtained.

It is effective to apply the micro-elastic theory forcalculating elastic constants of a composite material.
The ratio of grain boundary to grain volume wasreadout from Fig. 2. We considered that the twokinds of materials were series-arranging in film
plane and parallel-arranging in film thickness
direction. So that the composite-modeled elastic

2. Difference between measured value andsimulation
The structure of SAW filter used in this work is
Si/ZnO/IDT. Figure 1 shows the simulation values(solid line), measured values of Rayleigh and
Sezawa waves (point) vs. the kh value of ZnO film
from 0.1 to 3.0. There is a tendency that thedifference between the measured values and thesimulation values increases with the film thickness.
It seems that the influence of the elastic constants isquite large in the case.
3. Reason of the difference

Scanning electron microscopy (SEM) image ofetched surface of the ZnO film is shown in Fig. 2.
The black areas are the grain boundary of the ZnO
film. The grain boundary is considered the reasonof the difference in propagation velocity and loss.
Therefore, a composite model was used to calculate
the material elastic constants for simulation of SAW
propagation properties.
-----------------------------------------------------------s754008@st.pu-toyama.ac.jp

constants will be much different to the crystal
values, resulting in a change of the velocity.
5. Simulation results
Figure 3 shows the simulation results of wave
velocity (line) using composite-modeled elastic
constants. The simulation values got closer to themeasured values for both Rayleigh and Sezawa
waves than those of before.
6. Evaluation of propagation loss
Complex elastic constants were introduced into
this model and used for evaluation of propagation
loss. The calculated values showed a good agreement with the measured values, as plotted in Fig. 4.
7. Summary
We considered that the velocity difference
between simulated and measured values was causedby the grain boundary of the ZnO thin film.
Therefore, a composite model based on microelastic theory was applied to calculate elastic
constants of the ZnO film, followed by simulationof the SAW propagation properties. As a result, it is
known that existence of the grain boundary was thereason of the difference between the simulation andmeasurement. Moreover, the loss was roughly
estimated by introducing complex elastic constants
and a good result was obtained. However, thedifference between simulation and measurement of
ZnO film with thicker thickness should be

investigated in further work.

ZnO/Si_SAW Loss Measured vs Caluculated
1.00E+03

Sezawa wave

Sezawa波

L o s s[ d B / c m ]v [m /s]

6000
5500
5000
4500
4000
3500
3000
2500
2000

LOSSRc[dB/cm]
LOSSSc[dB/cm]
LossRm[dB/cm]
LossSm[dB/cm]

1.00E+02

Rayleigh波

Rayleigh wave

0

0.5

1

1.5

2

2.5

3

3.5

kh
Fig.1 Difference of measured and simulated
SAW velocity vs kh.

1.00E+01
2000

2500

3000

3500
v[m/s]

4000

4500

5000

Fig. 4 Calculation result of loss vs velocity.
8. Reference

Fig. 2 SEM image of etched surface of ZnO film.

6000
5000

v[m / s ]

4000
3000
2000
1000
0
0 0.5 1 1.5 2 2.5 3 3.5 4
kh_ZnO

Fig. 3 Velocity simulation using composite-modeledelastic constants.

1. J. J. Campbell, et al.: IEEE Trans. Sonics andUltrason. pp. 209-217, (1968)
2. F. Takeda, T. Shiosaki, and A. Kawabata: The 5th
symposium on USE (1984)
3. F. Takeda et al.: JJAP. Vol.24 (1985) pp. 124-124
4. Respondent the 50th meetings of JSAP
27a-ZM-4(2003.3)
5. Respondent the 51st meetings of JSAP
31p-YG-1(2003.9)
6. T.Karaki and et al.: JHES, (2003)
7. M. Furuhata, et al.: Proc. Symp. Ultrason.
Electron. Vol. 25 (2004) pp. 211-212
8. M. Furuhata, et al.: (2005) IEEE Ultrason. Symp.
pp. 2194-2197
9. H. Fukuda and G. BEN: Mechanics introductionof composite materials: ISBN-10, 4-7722-1373-2(1989) P210
10. JSME Computational Mechanics Handbook(Vol I):ISBN-10, 4-8889-8085-3 (1999) P240
11. Elasticity element technological handbook:ISBN-10, 4-2740-3365-1 (1991) P319 Table 4.21
12. Elasticity element technological handbook:ISBN-10, 4-2740-3365-1 (1991) p320 Fig. 4.91

1P5-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 151- 152
11-13 November, 2008

Speeding-up effects of aluminum oxide films on surface acoustic wave on
cystalline quartz
Wen-Ching Shih, Tzyy-Long Wang*, and Yi-Ling Kuo (Graduate Program in Electro-Optical Engineering,
Tatung University, Taiwan, R.O.C.)

Abstract

Aluminum oxide (Al2O3) films have beensuccessfully deposited on ST-cut quartz
substrates by electron beam evaporation
without any interlayer between them to ensure
a good adhesion of the Al2O3 films to quartz
substrates The Al2O3 thin films increase thesurface acoustic wave (SAW) velocity
sufficiently, and they can be used for
improvement of the performance of the SAW
devices. The effect of accelerating SAW by the
Al2O3 thin films has been measured anddiscussed. The results show that SAW phasevelocity in the Al2O3/quartz structure increases
with inserting an Al2O3 film. It is observed thatthe 1.45μm thick Al2O3 film is able to speed up
SAW by 3.28% at 271 MHz for Al2O3/quartz
sample.
1. Introduction

It has been reported that high hardness
diamond-like carbon (DLC) films deposited on
the surface of LiNbO3, quartz and LiTaO3
substrates can speed up the surface acoustic
wave (SAW) [1-5]. The velocity change
obtained has been shown to reach a level that is
sufficient for application in SAW devices. An
efficient SAW reflector, containing DLC
reflecting arrays on LiNbO3 substrate, has been
prepared making use of this speeding-up effect[6]. Al2O3 also possess many attractive
properties including: high hardness property,
chemical stability, high thermal conductivity
and electrical isolation. In this paper, we will
examine the speeding-up effect of Al2O3 films
on SAW on crystalline quartz substrates.
2. Experimental procedure

Interdigital transducers (IDTs) wit
h3μm
line-width and line-to-line spacing were

fabricated on the ST-cut quartz substrates by aconventional photolithographic technique andthe etching process. Each transducer has a 12
μm pe
r
i
oda
nd1.
2mm a
pe
r
t
ur
e
.Thenumberof
the finger pair is 100 and the propagation
distance between the input and output
transducers is 3 mm. After the fabrication of the
IDTs, we deposited the Al2O3 films on above.
The Al2O3 films used in this study wereprepared using electron beam (e-beam)
evaporation of the Al2O3 pellet. The
background pressure was below 5×10-5 torr.
The deposition conditions are DC current of 70
mA, substrate temperature of 300°C anddistance of evaporation source to substrate of
15 cm.
The thickness of the Al2O3 film wasmeasured by Dektak3STα-step surface profiler.
The stoichiometry of the Al2O3 buffer layerwasmeasuredbyenergy dispersive
spectroscopy (EDS). The cross-sectional
morphology of the films was examined byusing field emission scanning electron
microscope（FE-SEM, JEOL JSM-6500F）,
whereas the surface roughness was estimatedusing the atomic force microscopic micrograph（AFM, Digital Instruments）under tapping
mode. The frequency response of the fabricated
SAW devices was measured by Agilent 8720ES
network analyzer.
3. Result and discussions

From the EDS measurement of the Al2O3
overlayer, we can see that the atomic ratio of
Al/O of the Al2O3 buffer layer is about 2/3,
which means that the quality of the Al2O3
overlayer deposited by e-beam evaporation is
acceptable for further application. Figures 1
and 2 show the measured frequency responses
for ST-cut quartz and Al2O3 (1.45μm
thick)/ST-cut quartz substrates, respectively.

The center frequency of SAW device without
Al2O3 overlayer layer was measured to be about
263 MHz, and the corresponding phase velocity
(
v=f
×λ
)c
a
l
c
ul
a
t
e
df
r
om t
hec
e
nt
e
rf
r
e
que
nc
yi
s
3156 m/s. On the other hand, the center
frequency of SAW device with Al2O3 (1.45 μm)
overlayer layer was measured to be about 271
MHz, and the corresponding phase velocity
calculated from the center frequency is 3252
m/s. From Figures 1 and 2, we can see thatwhen we add an Al2O3 film layer, the center
frequency and the phase velocity of thefabricated SAW devices were also increased. It
is observed that the 1.45μm thick Al2O3 film isable to speed up SAW by 3.28% at 271 MHz
for Al2O3/quartz sample. The result is better
than those published in the literatures fordiamond-like carbon/quartz structure.

μm thick Al2O3 film. The result is better thanthose published in the literatures [3,4] fordiamond-like carbon (1 μm)/SiC buffer
layer/quartz structure with the velocity change
ratio of 2.3 % .

Fig. 2. The measured frequency response of the SAW
filter for Al2O3 (1.45μm thick)/ST-cut quartz substratewith electrode width of 3 μｍ.

Acknowledgements
This work was sponsored by the Tatung
University, Taiwan, R.O.C.. The authors deeply
appreciated their financial and technicalsupport.

References

Fig. 1. The measured frequency response of the SAW
filter for ST-cut quartz substrate with electrode widthof 3 μｍ.

4. Conclusions

The Al2O3 films with thickness up to
2.4μm have been successfully deposited on
ST-cut quartz substrates by e-beam evaporation
without any interlayer between them to ensure
the adhesion. The effect of the thickness of the
Al2O3 films on speeding up the SAW has been
confirmed. The phase velocity of the fabricated
SAW device in the Al2O3/quartz structure wasincreased with increasing the thickness of the
Al2O3 film. The SAW is accelerated by 3.28%
at 271 MHz for Al2O3/quartz sample with 1.45

[1] Q. Zhang, S.F. Yoon, S. Zhgoon, B. Gan, J.
Ahn, A. Revkov, Rusli, Thin Solid Films 360(2000) 274.
[2] S. Zhgoon, Q. Zhang, S.F. Yoon, A.
Revkov, B. Gan, J. Ahn, Rusli, Diamond Relat.
Mater. 9 (2000) 1430.
[3] Q. Zhang, S. F. Yoon, S. Zhgoon, V.

Ligatchev, M. B. Yu, J. Ahn, Rusli,

Diamond Relat. Mater. 10 (2001) 1843.
[4] Qing Zhang, S. F. Yoon, S. Zhgoon, V.
Ligatchev, J. Ahn, Rusli, Z. Sun, Thin Solid
Films 397 (2001) 276.
[5] Jingze Tian, Qing Zhang, Q. Zhou, R.

Gruenwald, M. Huesgen, S.F. Yoon, J. Ahn,
Surf.Coatings Technol. 198 (2005) 198.
[6] S. Zhgoon, Q. Zhang, S.F. Yoon, A.
Revkov, B. Gan, J. Ahn, Rusli, IEEE 48 (2001)202.

1P10-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 153- 154
11-13 November, 2008

Research on photo-thermal signal of a scheffelera
arboricola caused by Dye laser radiation
Dye レーザ照射によるカポックの熱波信号に関する研究
Yoshiaki Tokunaga, Masatoshi Yoshimura, Yukihiro Ishimaru†,
and Junji Hirama (Kanazawa Inst. Tech)
得永嘉昭，吉村政俊，石丸幸大‡，平間淳司（金工大）1. Introduction
Recently, it has been focused the spotlight ofattention upon environment and life. Saying
specifically, they may be problems on CO2
increment, on energy crisis and on food lessproduction. One of keys for solving of these
problems is to find out method on effective usage ofplant’s potential capabilities. We begin on a newresearch on photo-thermal effect of a plant and ascheffelera arboricola (hereafter called kapok) is
selected to study. Although electrical behavior of akapok by photo-irradiation has been done in details
by one of present authors[1], photo-thermal effectof it caused by laser radiation has been investigatedscarcely. In this paper we describe experimental
results of “in vivo” measurement on photo-thermal
effect caused by irradiation wavelengths with
633nm or 570 nm on a costa or an edge of the
kapok’s leaf.

In this configuration thermal wave from theirradiated surface of the leaf to opposite side of it
can be measured.
Figure 2 shows a sensing system. Dye laser(Spectra Physics: 375B) by Ar laser pumping wasused as an excitation source for changing
continuously from 570nm to 700nm. An
acousto-opticalmodulator(Gooch&Housego:
M080-2B) was used for frequency modulation of
the Dye laser light. PVDF film (Tokyo sensor
Co.Ltd,3-1003702-4) with 110μm was used as asensor material. Lock-in amplifier (NF: LI-574A)
was used for signal processing.
An energy transfer optical fiber (Edmund Optics:
UV/VIS 1000[μm]) was used to lead laser light on
the leaf. Irradiation beam diameter on the leaf wasabout 3mm and it’s energy density was about
1.41[mW/mm2] in order to prevent irradiation
damage.

2. Sample preparation and sensing system
Figure 1 shows a principle of “in vivo”
measurement of photo-thermal signal. In this figure,a schematic position between laser irradiation andpoly(vinylidene fluoride) (hereafter called PVDF)
sensor at the kapok’s leaf is shown.

Fig.2

Sensing system

3. Experimental results and discussion

Fig.1 “In vivo ”measurement of the leaf-----------------------------------------------------------toklab@mlist.kanazawa-it.ac.jp

We can do total and detail discussions on opticalstimulus of kapok by adding experimental data on
the photo-thermal effect since we have alreadycollected many experimental data on bio-electricalpotential [1].

Figures 3(a) and (b) represent amplitudedependence of the signal on modulation frequencyof laser induced thermal wave (hereafter called
LITW) when irradiation wavelengths are 570nm
and 633nm. In these figures ordinate represents
signal amplitude of LITW and abscissa delineateslaser modulation frequency. In the case ofirradiation on a costa of the leaf, the frequency
dependence was f-0.80 for 570nm irradiation and f-0.51
for 633nm one when the modulation frequency waschanged continuously from 10Hz to 100Hz. On theother hand, in the irradiation near the edge of theleaf, amplitude dependence was f-0.92 for 570nm
irradiation and f-0.74 for 633nm one as shown in Figs.
4(a) and (b). From these experimental results theamplitude dependence was different between the
costa and the edge of the leaf. In addition we foundthat phase in the 633nm irradiation was delayed
about 20 degree in comparison with that of the
570nm irradiation.

4. Conclusions
We described “in vivo” measurement on
photo-thermal effect of leaf of the kapok caused by
633nm irradiation or 570 nm one.
References1). J.Hirama et.al., J.SHITA. 9(2) (1997), pp.103106.[in Japanese]
Acknowledgments

The authors would like to thank prof.
N.Miyamoto at Kanazawa Institute oftechnology for his valuable cooperation andsuggestions.

100

f - 0 .8 0

10

Amp litu de[mV]

Amp litu de[mV]

100

1

0.1
10

100

f - 0 .9 2

10

1

0.1
10

10 00

100

Fr equ en cy[Hz](a) 570nm irradiation(a) 570nm irradiation
100

Amp litu de[mV]

Amp litu de[mV]

100

10

1

0.1
10

10 00

Frequ en cy[ Hz]f - 0 .5 1

100

10 00

10

1

0.1
10

f - 0 .7 4100

Fr equ en cy[Hz]Fr equ en cy[Hz](b) 633nm irradiation
Fig.3 case of costa(b) 633nm irradiation
Fig. 4 case of edge

10 00

1P10-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 155- 156
11-13 November, 2008

Active ultrasonic SONAR system of bat- Relationship between 3-D flight path and acousticalcharacteristics of echolocation sounds during foraging 生物超音波によるアクティブソナーシステム～採餌行動時における野生コウモリの 3 次元飛行ルートと放射パルスの関係～
Emyo Fujioka 1‡, Shigeki Mantani 1, Shizuko Hiryu 2, Hiroshi Riquimaroux 2 andYoshiaki Watanabe 2 (1Facult. Eng., Doshisha Univ.; 2Facult. Life and Medi. Sci.,
Doshisha Univ.)

藤岡慧明 1‡，萬谷重樹 1，飛龍志津子 2，力丸裕 2，渡辺好章 2 (1 同志社大 工; 2 同志社大 生命医科)dth0902@mail4.doshisha.ac.jp

A
y

0.9 m

z

2.25 m：x

MICROPHONE

A/D Converter

PC

B

10

z

[m]

5

x
-10

-5

0

10 [m]

5

Measured Range [m](Sampling 500kHz)

5
4
3
2
1
0
0

C

10
8
6
4
2
0

1

2

3

4

5

Actual Range [m]A

SearchTerminal
Approach

Search＊Amplitude [V]Amplitude [a.u.]

Fig. 1 (A) Four-microphone array system. Open arrow
indicates the position of each microphone. (B)Theoretical range error of the microphone array system.
The error was estimated to be less than 10 cm (gray area).
Cross mark indicates the position of the microphonearray. (C) Calibration measurement for the microphonearray. Circles indicate the measured ranges and dottedline indicates the position error (see text).

00
100 msB
Freq. [kHz]2. Materials and Methods
The Japanese house bats (Pipistrellus
abramus) were used in this study. The fundamental
component of the pulse is downwardly modulated
from 100 kHz to 40 kHz [3].
Sound recordings were conducted for 6 days
during a 1-hour period before and after the sunset.
Emitted echolocation pulses were recorded with 4omni-directional condenser microphones (Knowles,
FG-3329) positioned about 2 m above the ground(Fig. 1A). The signals were digitized with 16 bit at
sampling rate of 500 kHz by using a DAQ device(NI PXI-6250, Tokyo, Japan). Theoretical range
error of the 3-D position measurement wasestimated to be less than 10 cm within target rangeof 7 m in front of the microphone array (Fig. 1B).
Prior to recording, the range error was measured byusing a loudspeaker (Pioneer, PT-R7, Tokyo, Japan).
We confirmed that maximum range error was smallenough; less than 3 % within target range of 5 m(Fig. 1C).
3. Results
Echolocation of the bats during foraging canbe generally divided into three phases; search,------------------------------------------------------------

approach and terminal (Fig. 2A) [4]. The batsemitted CF-like (Constant-Frequency-like) pulses
during search phase. However, the frequency

Error [%]

1. Introduction
Bats and dolphins emit ultrasonic sonar
sounds to obtain surrounding information. The
systems they use are called bio-SONAR, and our
final purpose is to reveal highly developed
ultrasonic SONAR system established by bats fromviewpoints of biology and engineering [1].
Amount of daily energy consumption of theecholocating bats is known to be much greater thanthat of other small mammals, and especiallyforaging activity requires a greater part [2]. In
addition, since the bats have to capture a plenty of
insect preys everyday, they are supposed toeffectively exhibit foraging, i.e. selecting rational
flight path to a target prey of interest.
In this study, the ultrasonic emitted sonar
sounds were examined for wild bats during foraging,combined with measurement of their 3-D flightpaths by using a four-microphone array system. We
investigated how the bats selected their flight paths
to capture small airborne insects effectively byinteracting echolocation and flight simultaneously.

120
90
60
30
0

-1.0

33

-0.5

26

0.0

24

0.5

22

10

2 ms

Fig. 2 (A) Representative sequence of echolocation
pulses during foraging in the field. The pulses were
numbered beginning at the timing of capture (openarrow). (B) Change in the frequency structure ofecholocation pulses before capturing. Asterisk indicatesthe phase transition to approach.

structure varied from CF-like to FM (Frequency
Modulation) and the bats shortened the pulse
duration after approach phase started (Fig. 2B *).
Fig. 3 shows a 3-D flight trajectory of a bat before
capturing a prey (numbers correspond to those of
the pulses in Fig. 2). The bat changed its flight
direction soon after starting approach phase (Fig. 3*), and then approached the target prey linearly. We
calculated the target distances from the bat to thetarget (capture point) from two different ways;
direct distance to capture (DDC; dashed lines in Fig.
3) and actual distance along the flight path tocapture (ADC; solid curve). If the bats exhibited astraight-ahead approach to the target, DDC
coincided with ADC. From three representative
flights shown in Fig. 4, we found that DDC
identical with ADC after the approach phase started.
In addition, the bats lengthened the pulse duration
at the coincident timing between DDC and ADC(Fig. 4C *). These findings suggest that the bats
immediately select a straight-ahead approach atarget prey before capturing and emission of long
CF-like pulse is required for the bats to start their
final approach to the target.

Flight direction: Direct distance to capture

Fig. 3 Three-dimensional flight trajectory of the bat
during the capturing flight shown in Fig. 2. Positions ofpulse emission were plotted along with the flighttrajectory.

that the flying bats selected a straight-ahead path toa target after the phase transition (Fig. 4). Thisimplies that the bats forecast the moving direction
and velocity of the insect prey. In addition, thecoincidence between DDC and ADC between
flights (Fig. 4) indicates that the bats start approachphase according to the relative direction or velocity
to the target prey. We will investigate how the bats
select their flight paths according to the movementof a target prey for effective foraging.
Acknowledgments

Moving distance to capture [m]Pulse duration [ms]This work was partly supported by a grant to RCAST at
Doshisha Univ. from MEXT of Japan: Special Research Grants
for Development of Characteristic Education from thePromotion and Mutual Aid Corporation for Private Schools
Japan, Innovative Cluster Creation Project.

Reference

1. S. Hiryu et al.: J. Acoust. Soc. Am., 121, No. 3, (2007) 1749.
2. G. Neuweiler: The biology of bats (Oxford University Press, NY,
2000) p.98.
3. E. Fujioka et al.: Proc. of Acoustics’08 Paris, (2008) 5933.
4. H. U. Schnitzler et al.: J. Comp. Physiol. A, 161, (1987) 267.
5. H. U. Schnitzler et al.: Advances in neuroethology, (1983) p. 801.

＊

[m]

[m]

B

[m]

＊

-1

＊

-1

-2

-2

-3

-3

-3

-4

-4

-4

-5

-5

-5

-6

-6

-6

-7

-7

-7

-2

10

-6

-5

-4＊-3

-2

-1

0

C

8

-8
-8

-7

-6

-5

-4

-3＊ -2

-1

0

-8
-8

10

10

8

8

6

6

6

4

4

4

2

2

2

0
-8

0
-8

-7

-6

-5

-4

-3

-2

-1

0

Direct distance to capture [m]

＊

[m]

0

0

-1

-7

[m]

＊
[m]

-8
-8

＊

Capture

A

[m]

0

26
33

4. Discussion
P. abramus in the field repeated capturing
insects every 2-3 seconds [3]. Therefore, the bats aresupposed to effectively find and approach a target
prey for a short amount of time. Our results showthat the flying bats lengthened the pulse duration
just before phase transition to approach (Fig. 4).
Since the CF-like pulse (Fig. 2) is assumed to be
useful for detecting an insect’s fluttering [5], the bats
may confirm the presence of a target prey by
emitting a long CF-like pulse, and then start their
final approach to capture the target. We also found

＊

24

22

10

[m]

-7

-6

-5

-4

-3

-2

-1

0

Direct distance to capture [m]

0
-8

-7

-6

-5

-4

-3

-2

-1 0
＊

-7

-6

-5

-4

-3

-2

-1

0

Direct distance to capture [m]Fig.
4Three-dimensional
flighttrajectories (A)and changes inmovingdistance to capture (B) andpulse duration(C) during foraging behavior
from the distance of 8 m tocapturing
point.

1P10-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 157- 158
11-13 November, 2008

Development of ultrasonic sensor for mobile robot tomeasure the normal direction and parallel of walls
壁面と平行移動するロボット用の超音波センサについて
Manabu Ishihara1†, Makoto Shiina2 and Shin-nosuke Suzuki1 (1 Oyama National
College of Tech. ;2 Advanced Courses, Oyama National College of Tech. Eng.)石原学 1‡，椎名誠 2，鈴木真ノ介 2 （1 小山高専電気情報; 2 小山高専専攻科）

1. Introduction
Ultrasonic sensors are used in various fields
because of their unique characteristics. One such
use is to provide positioning control for robots.
Although ultrasonic ranging provides excellent
distance resolution, one of its shortcomings is that itprovides low directionality when compared to
optical sensors. Various attempts have been made to
improve measurement resolution, including the useof rotating and/or multiple frequency sensors, aswell as the adoption of a sophisticated signal
processing technique [1][2].
In this study, We investigated a method
believed to be capable of controlling a moving bodyin a way that allows it to maintain a user-specified
distance from nearby walls. The method uses
multiple ultrasonic sensors and a simple signal
processing method.
2. Sensor Outline
2.1 Ultrasonic Sensor Characteristics
One of the characteristics of ultrasonicsensors is that their aerial transmission speed isslower than light, which makes its signal processing
easier. Furthermore, ultrasonic wavelengths are
relatively short (approximately 8.6 mm at 40 kHz),
which allows for high resolution in the direction of
distance. This makes it possible to conduct highly
accurate distance measurements. Another advantage
is that ultrasound is unaffected by the color of an
object and can thus be used to measure the distancefrom a sensor to a transparent body such as a glass
object. Ultrasound is also relatively immune toeffects of light and airborne dust, which makes it
useful for performing measurements in outdoor
environments. Because of these characteristics,
ultrasonic sensors are also used for automobile
navigation and ranging systems, etc.
2.2 Conventional Sensor System
One example of a conventional ultrasonicsensor system is an ultrasonic rangefinder.
Ultrasonic rangefinders emit ultrasonic pings,
which travel to an object and are then reflected backto the rangefinder. Distance is calculated bymeasuring the time between the emission andreception of the reflected ping.
Figure 2 shows this scheme. Ultrasonicsensors of this type are often used for collision
avoidance by measuring the distance from a moving
vehicle to a potential obstacle. While it is possible
to use multiple units for this type of echo-ranging,as shown in Fig. 3, adequate distance between thesensors as well as careful consideration of thearrangement of multiple sensors is required insituations where the robot is cylindrically shaped.

Fig. 1 Equidistant control
Voltage

Wall

Reflection
time

Burst
Pulse

UltrasonicSensorTime

Fig. 2 Ultrasonic measurement system
Wall

Rob
ot

Mov
e
dire ment
ctio
n

Rob
ot

Mov
e
dire mentctio
nFig. 3 An idea of sensor arrangement

Wall

y

x is shortest distance


t
bo
Ro

Fig. 4 Outline of measurement system

3.

Proposed System

3.1 Measurement Principle
We will now examine a situation where arobot is required to move parallel to a wall, as
shown in Fig. 1. If we can somehow simultaneously
measure the minimum distance x between thesystem and the wall, and the distance to the wall yin the frontal direction of the system, we then knowthat the robot is moving parallel to the wall when x
and y are equal. Using these measurements, we candetermine the system’s inclination angle as well.
The relation between the angle θ, x and y isexpressed as:
EquationCosθ＝ X/Y
(1)
Then,
(2)
Equation
θ＝Cos −１（X/Y）
Thus, the system is controlled to satisfy the
relation θ= 0 [deg] in the equation (2). When arobot is controlled in a real system, the x and yvalues are measured constantly and the robot’smovements are controlled to ensure they stay within
the given threshold values. In addition, because thismethod uses measured angles as parameters,
positioning control can be determined easily.
3.2 Minimum Distance Measurement
The minimum distance between the wall andthe system x has to be measured even when thesystem (the axis of the sensor) is somewhat tilted,
as described above. Here we will call the sensor formeasuring the distance x as X. When measuring theminimum distance, the broad directional angle ofthe ultrasonic sensor is utilized. As shown in Fig. 5(a), ultrasonic sensors typically have a widemeasurable range, i.e. directional angle. In otherwords, even when the ultrasonic sensor is slightly
tilted, as shown in Fig. 5 (b), the measured distanceis approximately equal to the minimum distance x.
In our system, the minimum distance is measured
using this feature.
3.3 Tilted Distance Measurement
If the system (the axis of the sensor) is notprecisely perpendicular to the wall, x ≠ y, and it isnecessary to measure the tilted distance to the wally. We will call the sensor for measuring the distancey as Y, which is shown in Fig. 6. In this situation,
the distance y is measured from the outermost partof the measuring range of sensor Y. An experiment
was therefore conducted to determine thedirectionality of the sensor.
4. Discussion
Using the proposed sensor system, thedistance between the sensor and the wall and theangle of the sensor relative to the wall were
measured at distances of 50 - 250 cm and at anglesof 0 –15 degrees (0 degree indicates that the sensor

axis is perpendicular to the wall). From these results,
it was concluded that the proposed system issuitable for use as the positioning control of a robotthat is designed to travel along a passage, such as acorridor.
Since the proposed system can be connectedto the position control circuit of a robot using othermicrocontrollers via I2C, or to a PC via RS-232, it
can easily be installed and used in other systems as
a position-detecting module.
From these observations, we feel it is safe to
say that the proposed sensor system offers sufficient
functionality to allow its use as a position
controlling platform for a robot, and that it can beapplied to small traveling robots.
5. Conclusion
A sensor system was developed using only
inexpensive and easily available components.
Based on the information obtained while designing,
manufacturing and testing the prototype, we
conclude the system proved to be sufficiently
capable for use in robots.
Future research will include achieving
positioning control of a small robot using thepresent system.

(a) Perpendicular with a wall(b) Change a direction
Fig. 5 Shortest distance measurement by the Ultrasonic sensor

Fig. 6 Change the direction of rotation by the Ultrasonic sensor

References
1. Y.Nagashima, A.Ohya and S.Yuta: The Journal of
the Acoustical Society of Japan. 51 (1994)39.
2. M. Okuyuki, A. Kimura, M. Ohki and M.Ohkita:
IEEJ-C, 128 (2008) 55.

1P10-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 159- 160
11-13 November, 2008

Target Detection Using Multiple M-sequence Signals
in Indoor Environments
M 系列信号の同時送波による室内ターゲット検出能の検討
Hiroshi Matsuo1‡, Tadashi Yamaguchi2 and Hiroyuki Hachiya3 (1 Graduate school of
Advanced Integration Science, Chiba Univ.; 2Resarch Center for Frontier Medical
Engineering, Chiba Univ.; 3Graduate School of Sci. and Eng., Tokyo Institute ofTechnology)
松尾宏 1‡，山口匡 2，蜂屋弘之 3 （1 千葉大 融合科学; 2 千葉大 CFME; 3 東工大 理工）

1. Introduction
An acoustic method in air has the potential toallow for the fast and accurate characterization of
object in air. Nevertheless, it is difficult to identify
acoustic signal from small objects clearly becauseof environmental noise and the scattering of thesignal on the object surface.
In this paper, we present the target detection
using multiple M-sequence signals in indoor
environments. By using M-sequence signal that is
one of coded signals, we are able to improve SN
ratio and to measure the reflected waves from asmall object that cannot be detected using a
conventional impulse. Simultaneous transmission ofmultiple M-sequence signals enable an effective
data acquisition. We discuss the cross-correlation
characteristics between different codes. Acoustic
imaging results of cylinder targets are presented.
2. Method

Table 1 Cross-correlated value of preferred pair.

k : odd number
k : even number(except in
multiples of 4)

oscilloscope

function
generator

filterspeakermicrophone
S1

・・・

Value
-(2(k+1)/2+1)-1
2(k+1)/2-1-(2(k+2)/2+1)-1
2(k+2)/2-1

Probability
~0.25
~0.5
~0.25
~0.125~0.75~0.125

S2

350 mm 300 mm 350 mm

1000 mm

150 mm

500 mm
500 mmFig. 1

M-sequences of degree n which have a sharp
auto- correlation peak can be generated by different
binary feedback shift registers of length n.
Cross-correlation properties are important when
multiple M-sequence signals are transmitted. Pairs
which have low cross-correlation value especiallycalled preferred pair (PP) exist except in degree ofmultiples of 4. Table 1 shows cross-correlation
values of preferred pair of degree k.
The experiment was conducted in an indoor
environment using the measurement system shownin Fig. 1. In this measurement, the phase modulated
M-sequence signals of degree 10, centered at 25
kHz were used. The sequence is repeated threetimes during each transmission to eliminate theeffect of sequence truncation. Stainless steel pipes
with diameters of 13 mm were used as targets.
DegreecomputertargetMeasurement system.

3. Results and discussion
M-sequence signal of code- number ‘3265’
was transmitted from a speaker (S1) to estimatecross-correlation properties in real environment. A
code-number such as ‘3265’ written in octal formshows the pickup position of the feedback signal
from the shift register. Received signals werecorrelated with same code as the transmitted
M-sequence ’3265’. Then the signals werecorrelated with M-sequences of a code name ‘3575’
and ‘2011’. A pair of codes ‘3265’ and ‘3575’ is apreferred pair. A pair of cods ‘3265’ and ‘2011’ isnot a preferred pair. The amplitude of correlated
signals with ‘3265’, ‘3575’ and ‘2011’ are shown in
Fig. 2, Fig. 3 and Fig. 4. In Fig. 3 and Fig. 4,
signals from 0 to 500 ms are the result of acorrelation with the direct waves at 100, 220, 340
ms shown in Fig. 2. Correlated results areequivalent to a random noise which can be called
correlated noise. This noise causes the fall of the
SN ratio when multiple M-sequence signals aretransmitted.
Table 2 shows maximum and average of theamplitude of the range from 100 to 222.76 ms
where there is not the influence of sequence
truncation. The frequency distribution of theMaximum [mPa]
93.66
11.71
11.92

Average [mPa]
0.93
2.90
2.79

1200
PP
notPP

1000
800
600
400

80

200

60

0
0

2

4
6
8
Amplitude [mPa]10

40

Fig. 5 Amplitude distribution.

20

500

0
0

Fig. 2

200

400
600
Time [ms]

800

1000

Correlated signal using code ‘3265’.

12
10
Amplitude [mPa]

Code
3265
2011
3575

Y position (mm)Amplitude [mPa]100

Table 2 Statistical value of amplitude.

Frequency

amplitude is shown in Fig. 5. In Fig. 5, the solidline shows the frequency distribution of correlated
signals with ‘3575’ (PP) and the dotted line showthat of correlated signals with ‘2011’ (not PP). The
average of the amplitude of ‘3575’ result is lower
than that of ‘2011’ result and the frequency of low
amplitude is high. These results agree well withtheoretical characteristics of M-sequence.
We transmitted M-sequence of code ‘3265’
and ‘3575’ which are preferred pair from eachspeaker in Fig.1 and captured reflected signals fromthe targets. The image using the received signals isshown in Fig. 6. It is difficult to detect the reflectedsignals from a distant target due to influence ofcross-correlation noise.

1000

12

0.9
0.8
0.7
0.6

1500

0.5
0.4

2000

8

0.3
0.2
0.1

2500
-500
0
500
X position (mm)64Fig. 6 Acoustic image.
2
00Fig. 3

4. Conclusion
200

400
600
Time [ms]

800

1000

Correlated signal using code ‘3575’.

12

Amplitude [mPa]

10
8
6
4
2
0
0

Fig. 4

200

400
600
Time [ms]

800

1000

Correlated signal using code ‘2011’.

In this paper, we present the target detection
using multiple M-sequence signals in indoor
environments. As a result of estimation ofcorrelated signals using a different code from atransmitted code, in the case of the preferred pair,the frequency of low amplitude is higher than otherpairs.
References
1. Y. Wang et al.: Jpn. J. Appl. Phys. 42 (2003) No.
5B 3206-3211.
2. K. Nishihara et al.: Acoust. Sci. Technol. 29(2008) 15-20.
3. H. Matsuo et al.: Jpn. J. Appl. Phys. 47 (2008)
No. 5B 4325-4328.
4. Y. Wang et al.: Jpn. J. Appl. Phys. 47 (2008)
No. 5B 4319-4324.
5. Y. Wang et al.: Jpn. J. Appl. Phys. 46 (2007) No.
7B 4490-4496.

1P10-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 161- 162
11-13 November, 2008

Design for High-Accurate Numerical Simulation of
Acoustic Field in Time Domain Using Finite DifferenceTime Domain (FDTD) Method and Pseudospectral Time
Domain (PSTD) Method
FDTD 法と PSTD 法による時間領域における音場数値解析の高精度設計法
Kan Okubo1†, Masaki Omiya1, Takao Tsuchiya2 and Norio Tagawa1(1 Faculty of System Design, Tokyo Met. Univ.; 2Faculty of Eng., Univ. of Doshisha.)

大久保寛 1‡，大宮理生 1，土屋隆生 2 , 田川憲男 1（1 首都大システムデザイン; 2 同志社大工）1. Introduction
Time domain numerical analysis of acoustic
fields has become investigated widely as a result ofrecent computational progress. To date, accurate
schemes are developed for acoustic simulation.
Some techniques have been proposed as anacoustic field calculation method; the finite
difference time domain (FDTD) method[1-3] isvery widely used for time domain numericalanalysis. The FDTD method by Yee, however,causes numerical dispersion error due to using 2ndorder finite difference (FD) approximation. To
overcome this problem, FDTD methods using
higher order spatial FD[1] have been proposed.
Meanwhile, a pseudospectral time-domain(PSTD) method[4] is examined. This method uses
Fourier transform to represent spatial derivatives in
the governing equations for the acoustic field.
Higher order FDTD and PSTD methods yieldsuperior accuracy in exchange for a more
complicated formulation. However, both methods
require to set a smaller time step than Yee-FDTD
method in order to maintain the accuracy. Therefore,
in some cases, these methods may use more total
CPU time; we need to consider the balance between
the accuracy in space and required CPU time indesign for high-accurate time domain numericalsimulation.
This study examines a design method foracoustic numerical simulation in time domain using
FDTD and PSTD, considering numerical dispersion
relation.
2. Dispersion relation
For simplicity, we consider one-dimensional(1-D) case. Then, in acoustic FDTD simulation, thenumerical sound velocity normalized by theoreticalsound velocity in medium is given as22 k ∆x  3k ∆x    ω∆t 
A sin 
 B sin 
 

2 
 k   2 
c n ' = c 0  ω   k ∆x + 3k ∆x    2ω∆t   . (1)  sin  2  
2
2


  
2

In those equation, cn ' is the normalized soundvelocity, c0 is the theoretical sound velocity, k is
the numerical wave number, ω is the angularfrequency, ∆t is the time step, and ∆x is gridsize. The coefficients are defined as A = 9 / 8 and
B = −1/ 8 in FDTD (2, 4) method[1]. If A = 1 and
B = 0 are used, Eq. (1) shows the normalized
velocity of FDTD method by Yee[2].
In Eq. (1), discritization in space and timecauses the numerical phase error. That is, if there isno error in regard to spatial discretization,2 ω∆t  k  c ( s ) n ' = c 0  ω    2ω∆t   .
 sin  2  

 
2

(2)

On the other hand, if no error in time,2 k ∆x  3k ∆x  A sin  + B sin 2 
 k  
 2   . (3)c (t ) n ' = c 0  ω  
k ∆x



2


2

Additionally, the numerical sound velocity of
PSTD method is given as Eq. (2), because it
theoretically causes no error in regard to spatial
discretization.
3. Results and discussion
Assuming that the Courant number is
Cn = v∆t / ∆x , we can obtain(4)
Cn ⋅ d [GPW] = d [TPP] ,where GPW and TPP represent grids per
wavelength and timesteps per period, respectively.
Figure 1 shows numerical sound velocity
versus GPW calculated by Eq. (3) for A = 1 , B = 0(2nd-order FD) and A = 9 / 8 , B = −1/ 8 (4th-orderFD). Results calculated using Eq. (2) for Cn = 0.25 ,0.5 and 1 are also plotted in Fig. 1. Here,considering the relationship of Eq. (4), we canillustrate different three top axes as shown in Fig. 4.

In this figure, if(5)c (t ) n ' ⋅ c ( s ) n ' = 1 ,then there is no numerical dispersion. That is,
FDTD algorithm provides exact solutions at theso-called magic time step ( A = 1 , B = 0 and
Cn = 1 ). Now, Eq. (5) is substitute intoc (t ) n ' − 1 / c ( s ) n ' = 0 .
(6)Equation (6) demonstrates that it is required toreduce the value of D = c ( t ) n ' − 1 / c ( s ) n ' in order torealize an accurate FDTD simulation.
Figure 2 shows c ( t ) n ' and 1 / c ( s ) n ' versus
GPW or TPP. In addition, numerical velocity ofcompact 4th-order FD is also illustrated in thisfigure. c ( t ) n ' for 2nd-order FD and 1 / c ( s ) n ' for
Cn = 1 are identical values. Moreover, we compare
the two results; c ( t ) n ' for 2nd-order FD and
1 / c ( s ) n ' for Cn = 0.25 .
Figure 3 shows total numerical velocity
cn ' calculated from Eq. (2). In this case, even if asmall time step is used to improve the accuracy of
the time integration, numerical velocity deviatesfrom the theoretical value in total, as is seen from
Figs. 2 and 3(a). On the other hand, In the case of
4th-order FD with Cn = 0.85 , numerical phase error
is also caused in total due to a large time step, as isshown in Fig. 3 (b).
TPP
100
100
10

1.4

Cn=1
Cn=0.5Conclusion

This study investigated a design method foracoustic numerical simulation using FDTD and
PSTD. By separately considering numericaldispersion relation in space and time, we canchoose an appropriate time step for spatial FD. We
will examine a design for asymmetric FDTD
method in near future.
References
1. A. Taflove: Computational Electrodynamics: The
Finite-Difference Time-Domain Method (Artech
House, Boston, MA, 1995)
2. K. S. Ye: IEEE Trans. on AP, AP-14 (1966) 302
3. M. Sato: Jpn. J. Appl. Phys. 44 (2005) pp. 4490
4. Q. H. Liu: Microw. Opt. Technol. Lett., 15(1997)
158

Cn=0.25100

1A=9/8, B=-1/8
A=1, B=0
100

10
GPW

Fig.1 Numerical sound velocity v.s. GPW or TPP.
100

TPP

100
50

10
10

10

10

100

c(s)n'(Cn=0.25)
1c n'
c(t)n'(A=1, B=0; 2nd order FD)

0.8

0.6
10
GPW

50

1

cn'
c(t)n'(4th order FD)

0.8

0.6

5

10
GPW

50

(a)
(b)
Fig.3 Numerical sound velocity v.s. GPW or TPP.

Cn=1
A=9/8, B=-1/8
compact FD
A=1, B=0
10
GPW

5

Fig.2 Numerical sound velocity v.s. GPW or TPP.

Cn=0.25
Normalized sound velocity

Normalized sound velocity

1

50

5

5

Cn=0.50.6

10c(s)n'(Cn=0.85)

Cn=0.25

0.8

TPP
50

1.2

0.8
0.6

TPP
50

Normalized sound velocity

1.2

4.

Normalized sound velocity

Normalized sound velocity

1.6

10 (Cn=0.25)(Cn=0.5)(Cn=1)

10

100

Next, we will discuss the multi-dimensional
calculation. There is no magic time step for FDTD
in two or three dimensional (2-D/3-D) simulation.
Because FDTD has numerical anisotropic behaviors
due to the difference of numerical wave number fora propagation angle. c ( t ) n ' for 4th-order FD(azimuthal angle of 45 deg. and 0 deg. in 2-D
calculation) and 1 / c ( s ) n ' for Cn = 0.25 , 0.4 and
0.5 are shown in Fig. 4. This figure indicates that in
2-D simulation, we must choose an appropriate
time step for the accuracy of spatial FD.
Additionally describing, PSTD method has
theoretically causes no error in regard to spatial
discretization. Therefore, it provides higher
accuracy, as time step is smaller.

1c(t)n'(4th order FD, 45 deg.)c(t)n'(4th order FD, 0 deg.)0.9

Cn=0.4
Cn=0.5

0.8
30

10

5
GPW

Fig.4 Numerical sound velocity in 2-D simulation.

1P10-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 163- 164
11-13 November, 2008

Two Dimensional Simulation of Nonlinear Acoustic Wave
Propagation Using Constrained Interpolation Profile (CIP)
MethodCIP 法を用いた非線形音波伝搬の 2 次元数値解析
Masahito Konno1†, Kan Okubo1, Takao Tuchiya2 and Norio Tagawa1 (1 Facult. System
Design, Tokyo Met. Univ.; 2Facult. Eng., Dosisha Univ.)
紺野正仁 1‡，大久保寛 1，土屋隆生 2, 田川憲男 1 （1 首都大院

⎛11. Introduction
To date, Numerical analysis has been
investigated for sound wave propagation. Now,
development of accurate numerical schemes is an
important technical issue. The ConstrainedInterpolation Profile (CIP) method is a novel
numerical scheme recently proposed by Yabe[1,2].
It is a kind of method of characteristics (MOC) andis a numerical scheme with high accuracy that
hardly caused numerical dispersion errors[1-5]. It
uses not only the value at the grid point but also
their derivatives to solve the problem of wave
propagation. Some of the authors reported
application of CIP method to the one-dimensional(1-D) nonlinear sound wave propagation in air[6].
In this study, numerical simulation of
two-dimensional (2-D) nonlinear sound wave
propagation in time domain is performed by CIP
method.

δ 1 = χ ⎜⎜

⎝ cv

r
∂p
= − ρ0 c02∇ ⋅ v +
∂t

δ1 2
∇ p
ρ0

,

β ∂p 2+
ρ0 c02 ∂tr∂v
1
δ2 2 r= − ∇p +
∇ v
∂t
ρ0
ρ0

,

1 ⎞⎟
4
, δ2 = ζ + η .
c p ⎟⎠
3(3)

In those equation, χ is the thermal conductivity,ζ is the bulk viscosity, η is shear viscosity, andcv and c p are the specific heat at constantvolume and the one at constant pressure,respectively.
Now, we solve Eq. (1) and Eq. (2) using time
splitting method. Using this method, the equations
are separately solved on advective term andnon-advective term. First, we denote the advective
term.
r r
For simplicity, we assume v = (v x ,0,0 ) inorder to analyze 1-D sound wave propagation of
the x-direction. When the medium dispersion andnonlinearity can be ignored, Eq. (1) and Eq. (2) canbe denoted as∂p∂ ( Zv)
+ c0
=0,
∂t
∂x
∂p
∂ ( Zv )
+ c0
=0,
∂t
∂x

2. Formulation
The governing equations for nonlinear
acoustic fields with velocity dispersion under theassumption of weak shock are given as follows.
Equation (1) is the continuity equation and Eq. (2)is the equation of motion.

−

システムデザイン; 2 同志社大 工）

where Z =(4)(5)

ρ 0κ is the characteristic impedance.

(1)

Then we solve Eq. (4) and Eq. (5) using the CIP
method[5]. Similarly, propagation in the y-direction
as well as in the x-direction can be calculated.
Next, we describe the non-advective terms.
We consider the dispersion and nonlinear terms
shown as(2)

⎛ ∂v ∂v y ⎞δ1 ⎛ ∂ 2 p ∂ 2 p ⎞hp = ⎜ 2 + 2 ⎟ + 2 β p ⎜ x +⎟ , (5)∂y ⎠ρ0 ⎝ ∂x⎝ ∂x ∂y ⎠ρ 0 is the ambient medium density, c0 = κ / ρ 0is the sound velocity of small amplitude , κ is thebulks modulus and β is the nonlinearity
parameter. δ 1 and δ 2 are respectively given ashvx =δ 2 ⎛ ∂ 2 vx ∂ v y ⎞+⎜⎟,ρ0 ⎜⎝ ∂x 2 ∂y 2 ⎟⎠

(6)

hvy =

δ 2 ⎛ ∂ 2 vx ∂ v y ⎞+⎜⎟.
ρ0 ⎜⎝ ∂x 2 ∂y 2 ⎟⎠(7)

2where p is the pressure, v is the particle velocity,

2

Here,

we

use the linear relation;∂p / ∂t = − ρ c ∂u / ∂x , ∇ ⋅ v = (−1/( ρ 0 c02 ))∂p / ∂t an
2
0 0

r

d ∂ v / ∂t = ( −1/ ρ 0 )∇p . Those non-advective
terms are calculated after calculating the advection
term [5].

Numerical demonstrations are made for 2-D
nonlinear sound propagation in air. Those verified
that the shock front is clearly calculated by the CIP
method.

3. Results and Discussion
We show the results of calculation for 2-D
analysis of the nonlinear sound wave propagation
using CIP method. Analytical parameters of
calculations are as follows: grid size,
Δx, Δy = 0.005 [m]; time step, Δt = 4.37 [μs];References
1. H. Takewaki, A. Nishiguchi and T. Yabe: J.
Comput. Phys. 61, (1985) 261.
2. Nakamura T., Tanaka R., Yabe T., Takizawa K: J.
Comput. Phys. 174, (2001) 171.
3. T. Yabe, X. Feng and T. Utsumi: J. of Comput.
Phys. 169 (2001) 556.
4. T. Aoki: Comput. Fluid Dynamics Jour. 4 (1995)
279.
5. T. Tsuchiya, K. Okubo and N. Takeuchi: Jpn. J.
Appl. Phys. 47. (2008) 3952.
6. T. Kamakura: Fundamentals of nonlinear
acoustics (Aichi-shuppan, 1996)
7. M. Konno, K. Okubo, T. Tsuchiya, N. Tagawa:
Jpn. J. Appl. Phys. 47 (2008) 3962.

medium, air; the sound speed, c0 = 340 [m/s]; thenonlinear parameter, β = 1.2 . Consequently, the
CFL number is 0.3. A single-shot pulse ofsinusoidal whose amplitude and frequency are
500[Pa] and 1[kHz] is given around ( x, y ) = (0, 0) .
Figure 1 shows the spatial distribution of the initialpressure. Here, the Blackman window is used iny-direction as shown in Fig. 1.
Figure 2 shows spatial distribution of thesound pressure at the time t = ts where

ρ0c02
βω p0

500

(8)

is the shock formation time. The results of thetype-M CIP and the type-C CIP are very similar.
Those clearly calculated the shock fronts associatedwith the nonlinear acoustic wave propagation.
Next, Fig. 3 shows the sound pressure versus
time. The observation point is ( x, y ) = (10, 0) [m].
i.e., the azimuthal angle is 0 degree. The results
demonstrate the generation of the higher harmoniccomponents with wave propagation.

Sound pressure[N/m2]

ts =

t=ts

250

0

-250

linear(Type-C CIP)
nonlinear(TypeM CIP)
nonlinear(TypeC CIP)

-500
13

12.8

13.2

x[m]

Fig. 2 Sound pressure distribution at ts
500

Sound pressure[N/m2]

4. Conclusion
The study first applies the CIP method to 2-D
nonlinear acoustic wave propagation in time
domain under the assumption of the weak shock.

linear (x=10[m])nonlinear (x=10[m])nonlinear (x=5[m])

250

0

-250

-500

x = 10[m]x = 5[m]0.02850.029

0.02950.03

0.01390.01440.01490.0154

Time[s]Fig. 3 Sound pressure versus time
Fig. 1 Initial sound pressure1J4-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 165- 166
11-13 November, 2008

Shear Mode Type Solidly Mounted Piezoelectric Resonator
Using a LiTaO3 Transducer
LiTaO3 トランスジューサを用いた横波ＳＭＲの検討
Takehiko Uno, Kei Kasahara and Hiroyuki Tashiro(Facult. Eng., Kanagawa Institute ofTechnology).
宇野武彦，笠原慧，田代博之 （神奈川工大 工）

1. Introduction
Solidly mounted piezoelectric thin film
resonator (SMR) is one of the promising bulk
acoustic-wave devices for frequency control in a
GHz band1-3). Thickness extensional mode SMR has
been studied up to the present date, because ofusing the c-axis oriented ZnO thin film for theelectromechanical transducer layer. Temperature
coefficient of frequency (TCF) is relatively large in
SMR because of the negative TCF of ZnO film.
This paper presents the possibility of thickness
shear mode SMR having low TCF. Rotated Y-cut(RY-cut) plate of LiTaO3 is used for the
piezoelectric layer of the SMR. Thickness shear
vibration of low TCF can be excited by parallel
electric field in RY-cut LiTaO3 plate. Simulation
result shows the possibility of zero TCF shear mode
SMR. The simulation result also shows that higheffective piezoelectric coupling constant will be
realized. Fabrication technique of the shear mode
SMR using LiTaO3 plate will be discussed.

Y'
W

l

λ/2

electrode

A
(a)

(L)
(H)
(L)
(H)

λ/4
λ/4

Substrate (Si or SiO 2 )electrode

l

λ/2
λ/4
λ/4

A
(L)
(b) (H)(L)(H)

Substrate (Si or SiO 2 )Fig. 1 Shear mode SMR by parallel field excitation.
A: Rotated Y-cut LiTaO3 film.

2. Construction of shear mode SMR

1

(1).

-----------------------------------------------------------tk_u-no@ele.kanagawa-it.ac.jp

0.8
LiNbO 30.6
kFigure 1 shows the SMR construction proposed
here. LiTaO3 rotated Y-cut plate is used as thepiezoelectric transducer. Under the transducer,
acoustic multi-layer reflector with low impedanceand high impedance layers is formed and mounted
on a substrate. Because of the pure shear acoustic
wave can be excited by an electric field parallel tothe a-axis, two types of electrode configurations
may be possible as shown in Fig. 1(a) and (b). In
this configuration, mechanical affect on thevibration by electrodes is very small and highresonance Q value will be obtained.
The characteristics of the SMR mainly depend on
the piezoelectric transducer. Electro-mechanicalcoupling constant, k, by parallel field excitation canbe calculated by ref. 4. For the RY-cut LiTaO3 and
LiNbO3, k is given byE
k = e16 ' / c 66
' / ε11S

Z'
X

LiTaO 3

0.4
0.2
0
0
(Y-cut)

30

60

90
120
(Z-cut)150

θ (deg)180(Y-cut)Fig. 2 Coupling constant of parallel field excitation.
Figure 2 shows cut angle dependency of k. The
maximum coupling constant value for LiNbO3 (LN)
is about 0.9 and that for LiTaO3 (LT) is about 0.5. In
spite of high electro-mechanical coupling,frequency temperature characteristic is not so goodfor LN. On the other hand, zero and positive TCF
can be obtained for LT as shown by Fig.3 curve (a).
In the calculation, constant values by Smith andWelsh5) were used. Temperature characteristics of
SMR depend also on the materials

30
20
TCF (ppm/ûC)LT

Multilayer
reflector
by sputtering

10(1) Preparation ofmultilayer reflector
on a LT thin plate

0

(a)

-10

Substrate(Si or SiO

LiTaO 3 plate(b)(2) Bonding on a substrate.
LT

LTElectrodeMultilayer
reflector

-20
-30
90

2)

120

θ (deg)150

180

Fig. 3 1st order frequency temperature coefficient.
(a) Rotated Y-cut LiTaO3 shear wave resonator.
(b) SMR by LiTaO3 RY-cut plate.
High Imp.: ZnO
Low Imp. : SiO2(amorphous)
Reflection layers: 8 (ZnO:4 + SiO2:4)of the reflector.
Curve (b) in Fig. 3 shows the calculated value ofthe SMR.
Negative TCF of ZnO is almost cancelled bypositive TCF of the amorphous SiO2, and the TCF
of SMR is almost same as the LT RY-cut plate.
However, practical temperature characteristics of
LT parallel field excitation resonators are somewhat
complicated6), the cut angle range for positive TCF
of SMR may be narrower than the range shown in
Fig. 3.
Figure 4 shows the calculated result of effective
electromechanical coupling factor of the SMR. Thek value is 85-90% of LT parallel field excitation
resonator plate for each cut angle. This means that75-80% of vibration energy is trapped in thetransducer.
0.5

Substrate

Substrate(3) Sputter etchingfor the LT plate(4) Formation ofelectrodes andlead wire bonding.

Fig. 5 Fabrication process of the SMR.
First, the multilayer acoustic wave reflector isdeposited on a LiTaO3 plate. Next, the resonator isbonded on a substrate. The third step is milling the
LiTaO3 plate. Because reactive etching of LiTaO3
impossible, sputter etching by Ar plasma is the only
way at present. The last step is electrode depositionand lead wire bonding.
4. Conclusion

A configuration of shear mode solidly mounted
piezoelectric resonator is proposed. UHF band
resonator having low temperature coefficient may
be possible to realize. The resonator may be
applicable for UHF band resonators, filters and highsensitive gas and liquid sensors.
Acknowledgment
This work is supported by a Grant-in Aid for Scientific
Research from the Japanese Ministry of Education,
Culture, Sports, Science and Technology.

References
0.4

K. T. McCarron and R. E. Rose:k

1. K. M. Lakin,

Proc. IEEE Ultrasonics Symp. 1995, p.905
0.3

2. H. Kobayashi, Y. Ishida, K. Ishikawa, A. Doi and
K. Nakamura: Jpn. J. Appl. Phys. 41(2002)3455

0.2
90

120

θ (deg)150

180

Fig. 4 Effective electromechanical coupling
constant of SMR.
Configuration conditions: Same as Fig.3 (b).
3. Fabrication process

Thin film of LiTaO3 is impossible at present.
Therefore, thin plate of LiTaO3 must be used. The
fabrication process of the SMR is shown in Fig.5.

3. K. Nakamura, S. Sato, S. Ohta, K. Yamada and A.
Doi: Proc. IEEE Ultrasonics Symp. 2003, p.1438
4. T. Yamada and N. Niizeki: J. Appl Phys.
41(1970)3604
5. R. T. Smith and F. S. Welsh: J. Appl. Phys.
42(1971)2219
6. T. Uno: Proc. Intern. Symp. Circuit and systems,
1979 ,p. 892.

1J4-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 167- 168
11-13 November, 2008

Monitoring of aggregation behavior of amyloid β peptide using
wireless-electrodeless quartz-crystal microbalance
無線・無電極 QCM を用いたアミロイドβ凝集過程のモニタリング
Yuji Fukunishi1†, Kenichi Hatanaka1 Hirotsugu Ogi1, 2, Masahiko Hirao1, Masayoshi Nishiyama3
1
Graduate School of Engineering Science, Osaka University.
2Life Phenomena and Measurement Analysis, JST PRESTO
2
Renovation Center of Instruments for Science Education and Technology, Osaka University.
1

福西勇志 1‡，畑中健一 1, 荻博次 1, 2,平尾雅彦 1, 西山雅祥 3大阪大学 大学院基礎工学研究科, 2 JST さきがけ，3 大阪大学科学技術機器教育リノベーションセンター

1. Introduction
Alzheimer disease (AD) is a kind of dementia
that causes the decline of cognitive faculty andchange in the personal character. Recent intensive
studies [1-3] demonstrated that Aβ peptide is thedominant pathogeny of AD. In a healthy people,
the concentration of the Aβ peptide is controlled by
specific enzymes and antibodies in the cortical areaof the brain. However, several factors make theconcentration of Aβ higher, and when it exceeds a
critical value, agglutinates of Aβ peptides areformed, resulting in neurotoxicity and cell
cytotoxicity [4]. Therefore, the aggregation
mechanism of Aβ peptide is very important for thedevelopment of drugs for AD. Many relative studies
were reported, but quantitative and real-timemonitoring of the aggregation process of Aβ
peptides has not been achieved because of themeasurement difficulty.
In this study, we focus on using quartz-crystal
microbalance (QCM) biosensor for the study of theaggregation behavior of Aβ peptides. QCM has
shown pronounced ability for studying recognition
behavior among biochemical molecules throughchanges of resonance frequencies of the quartz plate.
The surface-modified quartz plate adsorbs target
molecules, resulting in the increase of the effective
mass of the resonator system and then in thedecrease of the mechanical resonance frequencies.
The resonance frequency can be monitored during
the binding reactions in real time without any
labeling, yielding thermodynamic binding constants.
The QCM is a mass-sensitive biosensor, and its
sensitivity deteriorates for Aβ peptides because Aβ
has a low molar weight (~4 kDa). Thus, it isrequired to improve the QCM sensitivity. Most
reliable approach is making the quartz-plate
thickness diminished, because the QCM sensitivity
is inversely proportional to the square of the
thickness. We propose a wireless-electrodelesstechnique for this and achieved advanced QCM
systems with much higher fundamental frequencies
up to 90 MHz [5-7].

Here, we study the aggregation behavior of Aβ
peptides using a 55-MHz wireless QCM wedeveloped and discuss their aggregation mechanism
quantitatively.
2. Experimental Procedure
The 30-µm thick AT-cut quartz plate, whose
fundamental resonance frequency is near 55 MHz,was used. For the gold-alkanethiol binding reaction,
we deposited 9-nm Au films after 1-nm Cr films on
both surfaces of the quartz plate. The crystal was
cleaned in the piranha solution (98%H2SO4: 33%
H2O2=3 : 7) , and after rinsing with ultrapure water,
it was immersed in a 10 mM 10-carboxy- 1pentanethiol solution for 24 h. The surfaces of thesensor were then activated using a 100 mM
1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide(EDC) solution. Then, the crystal plate was
immersed in a 50 µg/ml 1-42-Αmyloid-β-peptide(Aβ1−42)/DMSO-PBS solution for 24h. After
blocking the crystal sensor for 1 h using a 50 mM
glycine, the sensor crystal was set in the handmade
sensor cell, and the sensor cell was incorporated in
the homebuilt flow-injection system as shown Fig.
1. The micropump provided a constant flow of
buffer solution (PBS; pH7.4) at flow rate of 500µl/min. The solution flowed sensor cell throughdegasifier and 3 m Teflon tube that made thesolution temperature stable at a set value (37℃).
The rf-bursts were applied to the generation
diversion valve
constant- temperature room

degasifier

Teflon tube
micro pump
1

2

3

4

5

6

7

waste

8

sensor cell

dumperout put
personalcomputerin putsuperheterodyne
spectrometer

Fig. 1 Homebuilt flow injection system[×10antenna to generate the shear-horizontal vibration of
the quartz in a noncontact manner. After theexcitation, the reverberating signals were received
by the receiving antenna, which entered into thesuperheterodyne spectrometer to measure the phaseand amplitude of received signal. As an analyte to
be injected, we used a 50 µg/ml Aβ1-42/PBS
solution.

∆f (Hz)0-500-1000 AΒ1-42 50 µg/ml
-1500

3.

ResultFig. 2 shows an example of observed
resonance-frequency change during the aggregationof the Aβ peptide. We succeed in monitoring theaggregation of the Aβ peptide despite its smallermolecular mass. After the injection, the resonancefrequency monotonically decreased, without
showing a saturation. Thus, the aggregation of thepeptide is clearly demonstrated.
4.

Discussion

According to the Sauerbrey equation [8], the rateof the change in the resonance frequency equals therate of the absorbed mass of the protein to theoscillator mass. The expression is shown as follows.
∆f
∆m
=−
f
M

(1)

Here , f , ∆f, M, and ∆M denote the resonancefrequency, the decrement of resonance frequency,
mass of the oscillator, and mass of the adsorbed
protein on oscillator, respectively. According tothis concern, the amount of the Aβ peptide that
adsorbed on the oscillator for 9 h is calculated as
3.55 pmol. This leads to the prediction of theaggregation rate that 144 Aβ monomers will
agglutinate in the brain on the area of 1 nm2 every
year. The previous study [9] showed that the Aβmonomer changed into the Aβ fibril for 6 h after theAβ monomer was incubated, indicating that 0.1 Aβmonomers agglutinate in the area 1 nm2 for 6 h after.
Thus, our measurement showed that nearly 1500
times Aβ monomers agglutinated for making fibril
compared with the previous study. Some study
reported that Aβ fibrils have cell cytotoxicity, andtheir cell cytotoxicity kill cells and cause AD [10].
Therefore, the concentration of the Aβ peptide weused in this study can cause AD. As above,measuring the aggregation of Aβ peptides
quantitatively can provide us with important
information about the inherent biochemical
property of Aβ peptides, and it helps us tounderstand AD.

0

2

4
6
Time [h]8Fig. 2 Frequency response during the aggregation of
the Aβ1-42 peptide
4.

Conclusion

We developed a high sensitivity QCM by
excluding wires and electrodes, and succeed inmonitoring the aggregate behavior of Aβ1−42(molecular weight 4kDa) without labeling. The
aggregation rate was estimated to be 144
molecules/(year ･ nm2), following the Sauerbrey
equation. The wireless-electrodeless QCM willcontribute to the study of the aggregation
mechanism of Aβ peptides.
Acknowledgment
This study was supported by Life Phenomena andMeasurement Analysis, PRESTO, by Japan Scienceand Technology Agency.
References
1. D. J. Selkoe: Neuron 6 (1991) 487.
2. E. Bossy-Wetzel, R. Schwarzenbacher, S. A.
Lipton:, Nat. Med. 10 (2004) S2.

3. D.J. Selkoe: Physiol. Rev. 81 (2001) 741.
4. D. Loo, A. Copani, C. Pike, E. Whittemore, A.
Walencewicz, and C. Cotman: Proc. Natl. Acad.
Sci. USA 90 (1993) 7951.
5. H. Ogi, Y. Fukunishi, T. Omori, K. Hatanaka, M.
Hirao, and M. Nishiyama: Anal. Chem. 80,(2008) 5494.
6. H. Ogi, T. Omori, K. Hatanaka, M. Hirao, and M.
Nishiyama: Jpn. J. Appl. Phys. 47 (2008) 4021.
7. H. Ogi, K. Motohisa, K. Hatanaka, T. Ohmori, M.
Hirao, and M. Nishiyama: Biosens. Bioelectron.
22, (2007) 3238.
8. G. Sauerbrey: Z.Phys. 155 (1959) 206.
9. Nuria Benseny-Cases, Mercedes Cocera, Josep
Cladera: Biochem. Bioph. Res. Commu. 361(2007) 916.
10. K. Girigoswami, S. Ku, J. Ryu, and C. Park:
Biomat. 29 (2008) 2813

1J5-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 169- 170
11-13 November, 2008

凹凸 SiO2/Cu 電極/ LiNbO3 構造弾性表面波デュプレクサ

Surface Acoustic Wave Duplexer composed of SiO2/Cu-electrode/LiNbO3 Structure

having convex and concave portions

中井 康晴†, 中尾 武志, 西山 健次, 門田 道雄 (村田製作所)
Yasuharu Nakai, Takeshi Nakao, Kenji Nishiyama, Michio Kadota (Murata MFG. Co.,Ltd.)A transition bandwidth between a transmission (Tx: 1850-1910MHz) and a receiving (Rx: 1930-1990MHz) of PersonalCommunication Services (PCS) handy phone in US is very narrow as 20MHz compared with other systems. Authors have alreadyrealized the 5.0×5.0×1.7 or 3.0×2.5×1.2mm3 size SAW duplexer for US-PCS which has a good temperature coefficient of
frequency (TCF) by using the SH wave on flattened-SiO2/Cu-electrode/36～48°YX-LiTaO3 structure and Rayleigh wave on
SiO2/Cu-electrode/120～128°YX-LiNbO3 structure. Though the surface of above-mentioned structures is the flattened SiO2,
authors also studied the shape of the surface of the SiO2. As a result, in addition to increase of reflection coefficient, the TCF andpower durability have been improved by making convex portions on the surface of the SiO2 over the IDT’s gap.

1. はじめにUSのPersonal Communication Service(PCS)の規格は、送信側と受信側の周波数間隔が 20MHz と非常に狭いため、適した電気機械結合係数、良好な周波数温度特性(TCF)、
大きい反射係数をもつ SAW 基板が必要である。著者らはこれまでに、SiO2 膜表面に凸部のない平坦化 SiO2/Cu
電極/36～48°YX-LiTaO3 構造の SH 波を用いた温度特性の良好な 5.0×5.0×1.7mm3 のワイヤボンディング
型 SAW デュプレクサや、さらに小型化のために送信側に SiO2/Cu 電極/120～128°LiNbO3 構造のレイリー波を用いたフリップチップボンディング型の小型 3.0×
2.5×1.2mm3 サイズや 2.5×2.0×0.48mm3 サイズ
SAW デュプレクサの開発や実用化を行っている(1)(2)。
フリップチップボンディング型の送信側の開発過程において、SiO2/Cu 電極/120～128°YX-LiNbO3構造の表面 SiO2 の形状について検討を行った。その結果、ギャップ部分の SiO2 表面を凸形状にすること
により、SiO2 表面が平坦な構造に比べ、電気機械結合係数の劣化なしに反射係数が増大した。また、従来の平坦構造に比べ耐電力性の面でより長寿命化することができた(3)。本稿ではそれらの結果について報告を行う。なお、SiO2 を用いた凹凸構造についてはいくつかの提案例があるが(4)(5)、著者らは、電極が Cuである点と表面を SiO2 で被覆した構造についての測定結果がある点で異なっている。
本稿の構造や計測結果などについては 2006 年に出願済である(3)。

2. 計算結果
これまで著者らによって、SiO2、電極、基板の組み合せのうち、Fig1(a)に示すような電極指に起因した
SiO2 の凸部をもつ構造や(b)のように SiO2 表面を平坦化した SiO2/Cu 電極/圧電基板構造が報告されている(1)(2)。平坦化は特性劣化防止のため、Cu 電極は大きな反射係数を得るために使用されている。今回、新たに Fig
１(c)(d) のように IDT のギャップ上部の SiO2 を IDT 膜厚と異なる厚さの凹凸形状にした構造の検討を行った。
ここで、
Fig1 のように基準となる第 1 の SiO2 膜厚を h1、-----------------------------------------------------------y_nakai@murata.co.jp

基準膜厚からの追加した第 2 の SiO2 膜厚を h2 とする。
これらの構造について有限要素法を用いて、温度特性、電気機械結合係数、反射係数の計算を行った。計算は、基板 126°YX-LiNbO3、電極 Cu、厚さ 0.04λ、メタ
ライゼイションレシオ 0.5 で行った。λは SAW の波長である。第 1 の SiO2 膜厚 h1 を 0.25λとして、平坦及び凹、凸形状の第 2 の SiO2 膜厚 h2 を上に追加した構造で計算した。
計算の結果、温度特性はいずれの構造においても第 2の SiO2 膜厚 h2 の増加すると、改善することがわかった。
電気機械結合係数については、(d)構造では第 2 の SiO2
膜厚 h2 の増加に対して、大きく減少するが、(b)・(c)構
造では第 2 の SiO2 膜厚 h2 の増加に対して、電気機械結合係数の減少は小さいことがわかった。
反射係数については第 2 の SiO2 膜厚 h2 の増加に対して、(b)・(d)構造で減少するが、(b)構造ではその減少量はわずかにすぎない。一方、(c)構造では第 2 の SiO2 膜厚 h2 の増加に対して、反射係数が増大することがわかった。
以上のことから、SiO2/Cu 電極/128°YX-LiNbO3 構造のレイリー波では、(c)構造にすることで、電気機械
結合係数の減少なしに TCF を改善し、反射係数も大きくすることが期待できる。(b)構造で、単に Cu 電極膜
厚を厚くしても反射係数は得られるが、(c)構造で得られるもう一つの利点については後述する。
hm
IDT

SiO2

hm

h1

IDT

SiO2

Substrate

Substrate

(a)

(b)
IDT

SiO2

h2
h1

IDT

SiO2

Substrate

Substrate

(c)

(d)

Fig1. SiO2/Cu-electrode/LiNbO3 structure

h2
h1

h2
h1

0.04

3.1port 共振子の試作結果

SiO2h1=0.25l

Meas.
0.03

Bandwidth

126°YX- LiNbO3 基板上に波長 1.95μm、対数 120
対、交叉幅 32.3μm、膜厚 0.04λの Cu 電極と、膜厚0.25λの SiO2 を用い 1port 共振子を作製した。作製した構造は、(b)・(c)構造の 2 つの構造である。
Fig2 に試作した 1port 共振子の温度特性測定結果を示す。両構造とも、第 2 の SiO2 膜厚 h2 の増加とともに温度特性が改善することが確認できた。
Fig3 に試作した 1port 共振子の比帯域幅を示す。両構造とも、第 2 の SiO2 膜厚 h2 の増加に対する比帯域幅の変化が小さいことが確認できた。
Fig4 に試作した 1port 共振子のストップバンド幅を示す。(b)構造では、第 2 の SiO2 膜厚 h2 の増加とともにストップバンド幅が減少するが、(c)構造では増加することが確認できた。

0.01

0.00
0.00

0.01l

0.02 lFig3. Bandwidth as a function of h2 thickness
0.07
Meas.

SiO2
Cu
LiNbO3

Stopbandwidth

SiO2
Cu
LiNbO30.05

SiO2/Cu 電極/LiNbO３構造の LN レイリー波においてギャップ部分の SiO2 表面を凸形状にすることで、反射係数や耐電力性が改善することを実測により確認した。また、デュプレクサを試作したところ同等の常温特性で温度特性が 3～5ppm/℃程度改善した。
これらの結果をもとに、US-PCS 向けデュプレクサ
の実用化にあたって、この凹構造を採用している。

0.04
0.00

0.01l

0.02 lh2 Thickness

0.04l

0.03l

Fig4. Stopbandwidth as a function of h2 thickness
0

Insertion Loss [dB]6.むすび

SiO2h1=0.25l

0.06

5.耐電力性の評価結果試作した 1port 共振子を用いて耐電力性の評価を行った。評価の結果、(c)構造で第 2 の SiO2 膜厚が増加するに従い耐電力寿命が、約 3 倍程度に改善することを確認した(6)。有限要素法を用いて、応力解析を行ったところ(c)構造にすることで、IDT に波の伝
播方向にかかる応力が、小さくなることがわかった。
この応力の低減が、耐電力性改善の一つの要因だと推定する。

0.04 l0.03l

h2 Thickness

4.デュプレクサの試作結果
1port 共振子の試作結果をもとにデュプレクサの試作を行った。第 2 の SiO2 膜厚 h2 が 0.02λのときの(b)・(c)構造の送信側フィルタの特性を Fig5 に示す。
ほぼ同等の特性を持ちながら、(c)構造では温度特性が 3～5ppm/℃改善することを確認した。

SiO2
Cu
LiNbO3SiO2Cu
LiNbO3

0.02

0

Cu
SiO2
LiNbO3

-20

-2

-40
-60

-4
SiO2
Cu
LiNbO3

-6

-80
1700

-8
1800

1900
2000
Frequency [MHz]2100

Fig5. Tx filter response of flattened structure andTCF [ppm/℃]

-5

Meas.

SiO2h1=0.25l

SiO2
Cu
LiNbO3

-15

-20
0.00

文 献

SiO2
Cu
LiNbO3-100.01l0.02 lh2 Thickness

conex structure

0.03l

0.04l

Fig2. Temperature coefficient of frequency as a functionof h2 thickness(1) M.Kadota, T.Nakao, N.Taniguchi, E.Takata, M.
Mimura,K.Nishiyama,T.Hada,and T.Komura: Jpn. J.
Appl. Phys., 44, (2005)p.4527-4531.
(2) T.Nakao, M.Kadota, K.Nishiyama, Y.Nakai, D.
Yamamoto, Y.Ishiura, T.Komura, N.Takada, R.Kita :Jpn. J. Appl. Phys.,46,(2007)p4760-p4763.
(3)木戸,中尾,中井,西山,門田：特願 2006-056378(2006.3.20)及び PCT/JP2007/051995(2007,2,6)(4)村沢,小西,大森,橋本,山口：圧電材料・デバイスシン
ポジウム 2008,P123-126.
(5)竹内,山之内：電子情報通信学会論文誌 Vol.J85-C No.9
p709-p716(6)中井,中尾,西山,門田:信学技報 Vol.108.No19(2008.3)
p11-p15

1J5-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 171- 172
11-13 November, 2008

ZnO/高密度電極/水晶構造高周波共振子型フィルタ
High Frequency SAW Resonator
electrode/quartz Structure

Filtercomposedof

ZnO/High-density-

門田 道雄, 中尾 武志, 松田 賢二†, 村田 崇基 (村田製作所)

Michio Kadota, Takeshi Nakao, Kenji Matsuda, Takaki Murata, (Murata MFG. Co.,Ltd.)Radio frequency filters with a narrow band width.and high attenuations are required in recent years. One of the substrates with asuitable coupling factor and an excellent TCF for this filter is a ZnO film/Al electrode/quartz substrate. However, the reflection
coefficient of this substrate has not reported, and both the RF SAW filter and the multiple mode resonator one using this substrate
have not been reported. In this report, an RF narrow band SAW resonator filter composed of the ZnO/high density metalelectrode/quartz structure was realized to obtain a suitable reflection coefficient, and it has minimum insertion loss of 2.08 dB,
bandwidths of 3.9MHz (0.054%), and excellent TCF of 4.0ppm/℃.

2. 解析結果
Fig.1 に ZnO 膜/ST-35ºX 水晶構造における電気機
械結合係数の ZnO 膜厚依存性を示す。著者の 1 人等が報告した ZnO/Al 電極/26ºYX 水晶構造トランス
バ ー サ ル 型 SAW フ ィ ル タ で は 、 ZnO=0.27 λ 、
Al=0.026λにて 0.37ppm/℃の良好な TCF を得ているが、今回多少 TCF を犠牲にしてでももう少し大きい
結合係数を得たいので、ZnO 膜厚は 0.5λを用いることにした。多重モード共振子型フィルタを設計する場合には、反射係数は重要なパラメータであり、上述の ZnO 膜と水晶を用いた IF 用トランスバーサ
ル型 SAW フィルタでは Al 電極を用いていたが、他の高密度な電極材料についても、反射係数の検討を行った。Fig.2、3 に ZnO 膜厚が 0.5λ、電極指のメ
タライゼーション比 0.5 における、各種電極の厚みに対する反射係数と結合係数を示す。図中に示した
形状で FEM で求めた Al における反射係数はマイナ
スを示し、Cu、Ni は 0.05λ近傍でプラスからマイナスに変化する。Au は示した範囲ではプラスを示したままである。一方、電気機械結合係数は電極間で多少差があり、示した電極の中では Al は大きいが Au
は小さい。Al 電極、Au 電極の厚みが 0.03λ、0.04
λ、0.05λにおける反射係数の ZnO 膜厚依存性を
Fig.4 に示す。ZnO 膜を厚くすることにより Fig.4 に示したように、反射係数は小さくなることがわかる。
ken2_matsuda@murata.co.jp

0.04
o

2

Quartz
ZnO

0.02

Cal.

o

Meas.

29 45'Y35 X :oo
42 45'Y35 X :ZnOCoupling factor : k

近年、MediaFLOTM や TD-SCDMA 等、RF 帯において高減衰で狭帯域(0.7%程度)なフィルタ特性が求められているものがある(1)。このようなフィルタ特性を実現するためには、適した電気機械結合係数と良 好 な 周 波 数 温 度 特 性 (TCF) を も つ 弾 性 表 面 波(SAW)基板が必要であり、平坦化 SiO2 膜/高密度電極/LiTaO3 基板を用いた狭帯域 RF フィルタの報告がある(1)。一方、この狭帯域フィルタに適した結合係数と良好な TCF をもつ他の材料として ZnO 膜/すだれ状電極(IDT)/水晶基板があり(2)(3)、著者の 1 人等によりこの構造を用いた携帯電話の IF 用 SAW トランス
バーサル型フィルタの報告がある(2)(3)。しかし、これまで、この構造を用いた RF フィルタや多重モード
共振子型フィルタの報告はない。本報告では、この
ZnO/IDT/水晶構造を用いて RF 用共振子型 SAW フィ
ルタの検討を行ったので報告する。

Fig.5 に ZnO 膜 0.5λ、電極膜 0.03λにおける反射係
数のメタライゼーション比を示す。メタライゼー
ション比 0.37 以上で Al の場合マイナスの反射係数を示し、Au の場合はメタライゼーション比 0.5 より
0.3〜0.4 の方が大きい反射係数を示している。また、その結合係数は図示していないが、Au の場合メタラ
イゼーション比 0.5 のときよりごくわずかに大きくなる。以上よりプラスを示す反射係数と電気機械結合係数を考慮し、ZnO 膜 0.5λ、Au 電極 0.03λ、メ
タライゼーション比 0.3〜0.4 近傍で設計することに
した。

ZnO

QuartzQuartz Rayleigh

ZnO

0.00
0.0

Quartz

0.2 λ

0.4 λ

0.6λ

ZnO thickness

0.8λ

1.0 λ

Fig.1 Electromechanical coupling factor of ZnO/quartz as afunction of ZnO thickness.
0.03

Reflection Coefficient (1 finger)

1. はじめに

0.02

ZnO=0.5λ

Au
Ni

0.01
0.00
-0.01

Al

-0.02

Cu

-0.03
-0.04
-0.05
-0.06
0.00

0.02 λ0.04 λ0.06 λ0.08 λ0.10 λIDT thickness

Fig.2 Reflection coefficient (1 finger) of ZnO/various
IDT/27ºYX quartz as function of IDT thickness at ZnO
thickness of 0.5λ.

0.05

ZnO=0.5λ

Al

Ni

Cu

0.03
0

0.02

Au

10

0.01
0.00
0.00

0.02 λ0.06 λ0.04 λ0.10 λ0.08 λIDT thickness
Fig.3 Coupling factor of ZnO/ various IDT/27ºYX quartz asfunction of IDT thickness at ZnO thickness of 0.5λ.

Insertion loss [dB]

Coupling factor :k

2

0.04

の向上やより詳細な設計を今後行っていく予定である。Fig.8 に-30〜85℃におけるフィルタの周波数変化を示す。その TCF は 4.0ppm/℃となっており良好
な温度特性を得られている。

20
30
40
50
690

Au=0.04λ

0.08

0.04
0.02
0.00

720

730

740

750

200

Al=0.02λAl=0.03λAl=0.04λ

100

-0.02
-0.04
0.0

710

Fig.7 Frequency Characteristic of the fabricated filter.

Au=0.03λAu=0.02λ

0.06

700

Frequency [MHz]

0.1λ

0.2 λ

0.3 λ

0.4 λ

0.5λ

ZnO thickness
Fig.4 Reflection coefficient of ZnO/IDT/27ºYX quartz asfunction of ZnO thickness at Au and Al thickness of 0.2, 0.3,
0.4λ.(Metalization ratio)

Frequency shift [ppm]

Reflection Coefficient(1 finger)

0.10

0

4.0ppm/℃463ppm

-100
-200
-300
-400
-40

-20

0

20

40

60

80

100

o

Temperature [ C]

Reflection coefficient(1 finger)

0.04

0.1

Fig.8 Frequency shift of the fabricated filter relative to

ZnO=0.5λ

Au=0.03λ0.03

temperature.

0.02

4.むすび

0.01

Al=0.03λ

0.00
-0.01
-0.02
-0.03
0.2

0.3

0.4

0.5

0.6

0.7

0.8

Metalization ratio
Fig.5 Reflection coefficient as function of the metalization
ratio.

RF 帯での狭帯域フィルタの材料として、適した結合係数と良好な TCF を持つ ZnO/Au-IDT/水晶構造について検討を行った。まず、計算により Au 電極を用いると比較的大きなプラスの反射係数が得られる
ことがわかった。次に、メタライゼーション比について検討を行い、Au 電極ではメタライゼーション比を小さくするほど、反射係数が大きくなることが分かった。そして ZnO/Au/水晶構造を用いて共振子型
SAW フィルタの試作を行い、最小挿入損失 2.08dB、
帯域幅 3.9MHz(0.054%)、良好な TCF 4.0ppm/℃を得た。

3.フィルタの試作結果
ZnO/Au-IDT/水晶構造を用いて MediaFLO(中心周
波数 719MHz、、帯域幅 5MHz)向け RF 帯における共振子型 SAW フィルタを試作し、Fig.7 にその特性を示す。ここで、設計パラメータは ZnO 膜厚 0.5λ、Au 電極 0.028λ、λ=3.62μm、メタライゼーション
比=0.3〜0.4 であり段数は 1 段である。Fig.6 より、最小挿入損失 2.08dB、3dB 帯域幅 3.9MHz(0.54%)の特性が得られた。所望の帯域より狭いが、ZnO 膜質

引用文献(1)T. Murata, M. Kadota, T. Nakao, and K. Matsuda: Jpn. J.
Apply. Phys. 47(2008)4101.
(2) M. Kadota, H. Kando: Jpn. J. Apply. Phys. 42(2003),3139.
(3)M. Kadota, H. Kando: IEEE Trans. Ultrason. Ferroelectr.
Freq. Control 51 (2004) 464.

1J5-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 173- 174
11-13 November, 2008

変調 IDT を用いた Cu 電極/15°YX-LiNbO3基板構造広帯域 DMS フィルタ
Wideband DMS Filter Employing Pitch Modulated IDTs
on Cu-Grating/15°YX-LiNbO3-Substrate Structure
宮本宗†，大森達也，橋本研也，山口正恆†(千葉大 院工)Takashi Miyamoto , Tatsuya Omori, Ken-ya Hashimoto and Masatsune Yamaguchi(Graduate School of Eng., Chiba Univ.)
This paper discusses the application of Cu-grating/15°YX-LiNbO3(15-LN)-substrate structure to the development of wideband
Double-Mode SAW (DMS) filters. This structure seems suitable for the current purpose because of its distinctive features such as
extremely large electromechanical coupling factor (circa 30%) and small attenuation with propagation. We applied the pitch
modulation technique for the design of IDTs to arrange multiple resonances properly. This arrangement is essential for the realizationof flat and wide passband. The result indicates relative bandwidth more than 12% and good out of band rejection are simultaneously
achievable. A DMS filter was fabricated on Cu-grating/15-LN substrate. The measured result agreed well with the design, and the
passband width of 11.9% and the minimum insertion loss of 1.7 dB were obtained at 900 MHz range.

する共振周波数 ωre が一致するか、Ye=0 となる
対称モードに対する反共振周波数 ωae と Yo-1=0
現在、携帯電話に代表される移動体通信機となる反対称モードに対する共振周波数 ωro が器の RF 段には DMS フィルタが多用されている。 一致するとき、入出力間を無損失伝送できる。
これはこの素子が優れた帯域外抑圧を持つフ
一般に、ωre と ωro は交互に現れる。また、ωaeィルタ機能に加えて、バラン機能やインピーは ωre より若干高い。そのため、複数の連続す
ダンス変換機能を併せて実現できることによる共振周波数で上記の無損失伝送条件を満足る。しかし、現行の DMS フィルタでは実現でするように設計できれば、その周波数範囲できる-3 dB 比帯域幅が、高圧電性結晶基板に平坦な通過域が形成できる[2]。なお、一般的
LiTaO3 を用いた場合でも数%程度と狭い。今後
な DMS フィルタ設計法では、反射器間の 2 種の移動体通信機器のデータ伝送量増加および類の共振と IDT が反射器として動作する際に中高速化を見据えると、さらに広帯域なフィル
央の空隙間で生じる共振の計 3 種を利用するこタの実現が必要である。
とが多い[3]。
一方、筆者らは Cu 電極/15-LN 基板構造上のCu 電極/15-LN 基板構造を適用した DMS フィ
高結合非漏洩 SH 型(高結合ラブ波型)SAW を利ルタを設計したところ、-3 dB 比帯域幅 10%以用すると、非常に広帯域で低損失なラダー型
上の非常に広帯域な通過特性を計算できるこ
SAW フィルタが実現できることを報告していとがわかった。しかし、それには ωre と ωro の間る[1]。この構造では、約 30%の非常に大きな隔を拡げるため、IDT 対数を数対と極端に少な
電気機械結合係数 K2 が得られるため、比帯域く設計する必要があった[4]。この場合、イン
幅 20%という非常に広帯域なフィルタを実現
ピーダンス整合のため開口長を極端に長くすできる。また、約 1,000 の高い品質係数 Q と小る必要があり、IDT における電気抵抗が増大しさな容量比 γ も同時に実現できるため、0.5 dBてしまうので現実的ではない。
程度の最小挿入損失を併せて実現できる。
そこで、広帯域 DMS フィルタ実現を目的とし、本構造の適用を以下検討した。
1. まえがき

2. DMS フィルタの動作原理
2IDT 構成の基本的な DMS フィルタは、Fig.1のように共振周波数の等しい 2 つの同一な
SAW 共振子を近接配置し、音響的に結合させた電極構造をとっている。これに生じる共振は、構造が左右対称なため、対称な界分布を持つ対称モードと、斜対称な界分布を持ち共
振 周 波数 が異 なる 反対称 モ ード に分 類で きる。
ここで、両 IDT を並列もしくはたすき掛けに並列接続した際に得られる実行的な 1 ポート
共振子のアドミタンスをそれぞれ Ye、 Yo とする。
この時、Yo=0 となる反対称モードに対する反共振周波数 ωao と Ye-1=0 となる対称モードに対†

walla-walla@graduate.chiba-u.jp

Fig. 1 Two-port DMS resonator.

Fig. 2 DMS filter using pitch-modulated IDTs.

3. 変調 IDT の利用
上述した問題を解決するため、Fig.2 の様に
IDT をいくつかに分割し、IDT 並びに反射器の電極周期を空間的に変調する手法[3]を素子構造に適用した。
この構造では、外側程 IDT の電極周期が大きくなるように設計すると、ω の増加と共に IDTの外側から順次反射器として動作する。従って、IDT 周期と共にその対数を調節することにより、数多くの周波数で上記の無損失伝送条
件を満足できるため、ωre と ωro の間隔をあまり拡げなくとも広帯域フィルタが設計可能となる。これにより、IDT の開口長を現実的な値にまで低減できる。また、利用する共振の数の増加によりフィルタのスカート特性が急峻になるという特長も生じる。さらに、設計の自由度が増大するため、あえて中央のスペースを与える必要がなくなる[4]。なお、SH 型 SAWを利用する場合、中央の空隙部における SAWの散乱損失が無視できない[5]ので、フィルタの低損失化にもこの手法は非常に有効だと言える。

挿入損失 1.7 dB (880.5 MHz), -3 dB 比帯域幅11.9%の非常に広帯域な通過特性が得られた。

Fig. 3 Microscope photo of fabricated device.
(400 μm × 700 μm)

4. 試作結果
今回、IDT を 4 分割して電極周期を変調した
Cu 電極/15-LN 基板構造 DMS フィルタを設計し、実際に試作を行った。
ただし、設計の際に用いるシミュレータには、Abbott らが提案した SH 型 SAW に対する
COM モデル[6]を適用した。なお、シミュレー
タ精度向上を図るため、別途用意した試作 1 ポ
ート共振子のアドミタンス特性と COM 解析結果との比較により決定したパラメータ[7]を計算には用いている。一方、試作には、走査型電子顕微鏡をベースとした電子線露光装置とリフトオフ法を組み合わせた方法[8]を採用した。
まず、試作素子の表面写真を Fig.3 に示す。
バスバーを除いた実質的なデバイスサイズは
180 μm × 129 μm となっており、堆積させた Cu
膜厚は約 250 nm である。次に、試作素子の通過特性 S21 を、計算値と併せて Fig.4 に示す。今回の試作では横モードの対策[1]を施していな
いため通過域に細かいリップルが見られるものの、最小挿入損失は 880.5 MHz において 1.7
dB であり、-3 dB 比帯域幅が 11.9%と低損失かつ非常に広帯域な特性となっている。
以上のように、Cu 電極/15-LN 基板構造と変調 IDT の利用により、非常に広帯域な DMS フ
ィルタが実現できることを実験的に示せた。
5. まとめ本研究では、広帯域 DMS フィルタ実現を目的とし、Cu 電極/15-LN 基板構造上の高結合ラブ波型 SAW の利用を検討した。また、素子構
造に IDT の電極周期を空間的に変調する手法[3]を採用して試作を行った。その結果、最小Fig. 4 Frequency response of fabricated DMS filter.

謝辞
本研究の一部は独立行政法人日本学術振興会科学研究費補助金並びに独立行政法人科学技術振興機構シーズ発掘試験研究の補助を受けた。
引用文献[1] T.Omori, et al: Proc. IEEE Ultrason. Symp.
(2006) 1874-1877.
[2] K.Hashimoto, et al: IEEE Trans. Ultrason.,Ferroelec. and Freq. Cont. 51 (2004) 1394-1403.
[3] K.Hashimoto, et al: IEEE Trans. Ultrason.,Ferroelec. and Freq. Cont. 54 (2007) 2152-2157.
[4] 宮本 他: 第 36 回 EM シンポジウム予稿集(2007) 63-68.
[5] O.Kawachi, et al: IEEE Trans. Ultrason.,Ferroelec. and Freq. Cont. 54 (2007) 2159-2164.
[6] B.P.Abbott and K.Hashimoto: Proc. IEEE
Ultrason. Symp. (1995) 239-245.
[7] 宮本 他: 日本学術振興会弾性波素子技術第150 委員会第 106 回研究会資料 (2008) 17-22.
[8] H.Hatakeyama, et al, IEEE Ultrason. Symp.
(2004) 1896-1900.

USE2008
The 29th Symposiumon
ULTRASONICELECTRONICS

Wednesday, November 12, 2008

2E1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 175- 176
11-13 November, 2008

Elastic Constant and Microstructure of Oxide Thin Films Studied byPicosecond Laser Ultrasounds
ピコ秒レーザー超音波法による酸化物薄膜の弾性定数測定と組織評価
Tomohiro Shagawa1†, Hirotsugu Ogi1, Nobutomo Nakamura1, Masahiko Hirao1, Hidefumi
Odaka2 and Naoto Kihara2 (1Grad. Sch. Eng. Sci., Osaka Univ.; 2Asahi Glass Co., LTD)
舎川知広 1‡，荻博次 1，中村暢伴 1，平尾雅彦 1，小高秀文 2，木原直人 2（1 阪大基礎工; 2 旭硝子）

1. Introduction

2. Brillouin Oscillations

Oxide thin films are used in many devices
because of their specific functions such as
piezoelectricity,transparency, and insulation
ability, and they have been recognized as important
industrial materials. Recently, oxide thin films areapplied to acoustic devices such as film bulk
acoustic resonator (FBAR), achieving an
ultrahigh-frequency bulk-wave filter.
These
devices must have an index of their reliability.
Elastic constants can be the index, because theelastic constants of films are significantly decreased
by defects.
Furthermore, they are importantparameters required in designing acoustic devices.
Thus, measurement of the elastic constants of thinoxide films is a very important issue. However,conventional techniques (microtensile tests,
microbending tests, nanoidentation, and so on) haveshown difficulty for determining accurate elastic
moduli because they are too much sensitive to thedimension errors and to many ambiguous
parameters.
In previous work, we revealed that picosecond
laser ultrasounds (PSLU)(1, 2) is an effective method
for the measurement of the elastic constants of thinmetal films(3, 4). PSLU technique is classified into
three methods; the pulse-echo method(3), thephonon-resonance method(4), and the Brillouinoscillation method(2, 5). Here, we use the last one
because it is effective for transparent materials andit does not require the thickness measurement,
which has been troublesome. There is no report
determining the elastic constants of thin films using
the Brillouin-oscillation method.
There are two purposes in this study. First, weestablish the accurate measurement method ofoxide thin films by Brillouin oscillation. Second,evaluate of microstructure of oxide thin films,
through the elastic constant. We measured theelastic constants of amorphous silica (a-SiO2) films
by Brillouin oscillations method. Measured elastic
constants highly depend on the microstructure.
We quantitatively discuss the relationship between
elastic constants and microstructure.

Brillouin Oscillations arises in the reflectivity
change of the probe light from the interference
between the reflected light at the film and thediffracted light by the ultrasound grating in thetransparent material. Because the grating moves
at the sound velocity, the interference light intensity
is oscillated as the ultrasound propagates. Its
frequency is determined by Bragg's law. When theprobe light enters the material perpendicularly, theBrillouin oscillation frequency fa takes the form

E-mail: shagawa@mbox.me.es.osaka-u.ac.jp

fa =

2nv

λo

,

(1)

where, n is refractive index of material, v is soundvelocity, and λo is wavelength of the probe light.
Thus, measuring the frequency and refractive index,
we can determine the sound velocity and then thelongitudinal-wave elastic constant.
3. Experiments
We deposited a-SiO2 films on (001) Si substrateby a reactive sputtering method. We changed
sputtering parameter such as sputtering pressure,
O2/Ar gas ratio, and sputtering voltage for making
various microstructures. Film thicknesses were200-1000 nm. The results of the x-ray diffraction
measurements showed that all samples were
amorphous. We observed the cross-section by
field-emission scanning electron microscopy(FE-SEM). For generating ultrasound, a 10-nm Al
film was sputtered on a-SiO2 films.
We used Ti-sapphire pulse laser with 100 fs pulse
width, 80 MHz repetition frequency, and 800 nm
wavelength. The light pulse was split two pulses.
One was the pomp light and the other was the probe
light. The pomp light was focused on the Al film togenerate ultrasounds through thermal expansion.
The probe light was frequency-doubled (400 nm
wavelength) and irradiated the sample to detect
Brillouin oscillations (λo=400 nm in Eq. (1)). The
refractive index n was measured by ellipsometry,
assuming the Lorentz-oscillator model.
The probe light and ultrasound pulse penetrated
to the Si substrate.
Hence, two Brillouinoscillations were usually observed. One was froma-SiO2, the other was from Si. Since, n of Si isfour times larger than that of a-SiO2, theBrillouin-oscillation frequency of Si wassignificantly larger than that of a-SiO2.
4. Results
Figures 1 and 2 show typical reflectivity changesof the probe light, including Brillouin oscillations,and the determined elastic constants of the a-SiO2
films, respectively. We observed no Brillouinoscillations of Si from samples S3 and S4, and theirelastic constants of the a-SiO2 films were lower
than the others by up to 30 %. The SEM images
showed that S1 and S2 exhibited smooth and flat
microstructures, while S3 and S4 exhibited roughand granular microstructures.

∆R (arb. units)

S1

S3

0

100

200

300

Time (ps)fraction.
We therefore develop a model to realize thestiffness decrease with defects of very small volume
fraction using micromechanics calculation.
Eshelby’s equivalent-inclusion method andMori-Tanaka mean-field theory yield themacroscopic stiffness of a composite composed ofisotropic matrix and inclusions as

[ (
) ][
A = [S(C ) (C − C ) + I ] .

CC = C M + f I CI − C M A d f M I + f I A d
d

M −1

I

−1

M

] , (2)−1

Where, CC, CM and CI are the elastic-stiffness
tensors of the composite, matrix, and inclusions,
respectively. S is the Eshelby tensor determined
by Poisson’s ratio of the matrix and the shape of the
inclusion. fM and fI are volume fractions of thematrix and inclusion, respectively. We assumed
pan-cake shape air inclusions for defects. Figure
3 shows the calculation result and estimated volume
fraction of measurement elastic constants ofsamples. These results explain severely decreaseof the elastic constant by small volume fraction of
the inclusion.
1

Fig. 1 Reflectivity changes from S1 and S2,
showing Brillouin oscillations.

S2
S3

0.9

CL / C L

Bulk

S1

0.8

CL (GPa)

80

S4

10

400 nm1

400 nm
CR071128-2 400 nm

2

3

10

-6

10

-5

-4

10

10

-3

10-2

Porocity

400 nm

70

60

-7

4

Specimen

Fig. 2 Elastic constants CL and cross-section
microstructures of a-SiO2 films.
5. Discussion
S3 and S4 had granular microstructure, indicating
scattering loss for the sound wave. Attenuation ofultrasounds by scattering is proportional to thefourth power of the frequency assuming Rayleighscattering. Therefore, as ultrasound propagates
SiO2 film, high-frequency components ofultrasound is attenuated drastically. There aremany factors of granular microstructure. However,concerning an amorphous, they are limited to
defects and precipitates. Especially, thin defects(nano-micro cracks) decrease elastic constants ofmaterials severely, despite nearly zero volume

Fig. 3 Relationship between the measured andcalculated elastic constants CL for the defects withthe aspect ratio 1/100.
6. Conclusion
We studied the elasticity of sputtered a-SiO2 thinfilms using Brillouin oscillations.
Granularsamples showed smaller elastic constants by 30%
and high sound attenuation.
Using themicromechanics modeling, we estimated volume
fraction of microcracks at lower than 1 %.
References
1.
2.
3.
4.
5.

C. Thomsen et al., Phys. Rev. Lett. 53, 989 (1984).
C. Thomsen et al., Phys. Rev. B 34, 4129 (1986).
N. Nakamura et al., Phys. Rev. Lett. 99, 035502(2007).
H. Ogi et al., Phys. Rev. Lett. 98, 195503 (2007).
A. Devos and R. Côte, Phys. Rev. B 70 125208(2004).

2E2aProceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 177- 178
11-13 November, 2008

High Temperature Integrated Ultrasonic Transducers forLight-Weight Metal Process Monitoring
高温一体型超音波トランスジューサによる軽金属成形モニタリングの検討
Makiko Kobayashi† and Cheng-Kuei Jen (Industrial Materials Institute, National
Research Council Canada)

1. Introduction
Light weight and high mechanical strength
metals such as magnesium (Mg) and aluminum (Al)alloys have become increasingly used for
manufacturers in automobile industry in order toenhance fuel-efficiency for ecology purpose. Liquidand semi-solid diecasting and thixmolding(injection molding of Mg alloys) are commonlyused production technologies for such materials.
High production rate and yield, and quality
assurance are crucial factors to ensure the successof these technologies and the increase of the use of
these materials.
Due to high pressure and high temperature(HT) and corrosive natures of Mg and Al in themolten state during the above mentioned production
processes, it is not simple to perform on-line
monitoring of temperature, pressure, microstructure,filling conditions and solidifcaton of the melt. In thepast delayed line ultrasonic probes [1] have beenutilzied to perform real-time monitoring of Al andMg alloy diecasting processes, however, theseprobes needed cooling and were bulky. Holes wererequired to be made in the die so that these probes
can be acommodated. It means that they areinvasive sensors. Furthermore, due to the HT andhigh pressure of the diecasting and thixomolding
processes the safety requirements prohibit the useof the above mentioned invasive delay line
ultrasonic probes at the nozzle. Any leak of molten
metals at any hole which accommodates theinvasive probe may lead to serious hazards tohuman lives. However, current commerciallyavailable broadband ultrasonic transducers (UTs)
have limitations for HT operations due to the lackof appropriate HT couplant and backing material.
They are also not convenient for use at curved
surfaces and not reliable under thermal shock orvibration condtions. Therefore HT non-invasive
UTs are desired for above mentioned real-timeprocess monitoring applications.
HT integrated UT (IUT) using piezoelectriccomposite ceramic films made by sol-gel spray-----------------------------------------------------------Makiko.kobayashi@cnrc-nrc.gc.ca

カナダ国立研究所）

technique were reported [2,3]. These IUTs can bedirectly fabricated onto curved surfaces such as
nozzles and die or mold inserts, do not needultrasonic couplant and have high signal strengthand broadband width. They seem suitable forreal-time non-invasive monitoring of diecasting andthixomolding processes.
Toward the demonstration of IUTs’
suitability for the above mentioned application
directions, in this study, two kinds of IUTs were
fabricated onto different substrates. Lithium niobate(LN)/ lead-zirconate-titanate (PZT) IUTs [3] were
fabricated onto a titanium rod and a steel pipe, andbismuth titanate (BIT)/PZT IUTs were fabricatedonto a real thixomolding mold insert in order toinvestigate their HT ultrasonic performance,
thermal shock and cycling resistance.
2. LN/PZT IUT onto a titanium substrate
A LN/PZT IUT was fabricated onto a
25.4mm diameter and 26.3mm height titanium rod
with around 10mm square platinum top electrode asshown in Fig.1. The detail description of fabrication
procedure for sol-gel spray technique can be foundin elsewhere [2, 3].Titanium rod and platinum paste
top electrode were selected because of their hightemperature durability.
IUT

Amplitude (arb.unit)

小林牧子†，任正魁 （工業材料研究所

L10

Fig.1 LN/PZT IUT
onto a titanium rod.

1

L

20

2

Time Delay (μs)

30Fig.2 Ultrasonic performanceof IUT in Fig.1 at 800°C

To examine the thermal shock resistance andHT operation capability, a propane gas torch wasused to heat the LN/PZT IUT shown in Fig. 1. Fig.2
shows the 1st , L1, and 2nd round-trip, L2, reflectedechoes from the bottom of substrate through the
thickness of the rod. The center frequency. 6dB
bandwidth and signal to noise ratio (SNR) of the L1

LN/PZT IUTs onto a steel pipe

IUTs

Amplitude (arb. unit)

In order to simulate the nozzle, a steel pipewith an inner diameter of 14.3mm, outer diameterof 38.2mm, and length of 43.5mm was chosen as a
substrate. It is noted that normally the nozzle of thethixomolding and diecasting machine can be
detached from the machine for IUT fabrication.
Two LN/PZT IUTs were then fabricated onto thissteel pipe at two opposite cylindrical convex sides
facing each other, as shown in Fig. 3. Thisconfiguration could allow the use of transmission as
well as reflection mode operation during processmonitoring. .
In order to simulate on-line monitoring at thenozzle, the pipe with LN/PZT IUTs in Fig. 3 wasfilled in silicone oil and ultrasonic measurement
was performed in transmission mode. The result isshown in Fig. 4. The transmitted signal throughsilicone oil was clearly observed at 200°C. The
real-time non-invasive process monitoring of
thixomolding and Al diecasting at the nozzle isbeing prepared and the results will be reported infuture.

10

Fig.3 LN/PZT IUTs
onto a steel pipe.

4.

IUT

Mold insert for Thixomolding

Fig. 5 BIT/PZT IUTs fabricated onto a mold insert for
Mg thixomolding machine.

L

20

1

L

2

40

Time Delay (μs)

L

60

3

Amplitude (arb. unit)

3.

fabricated piezoelectric composite films.
Since the temperature of mold insert asshown in Fig. 5 is lower than 450°C, BIT/PZT IUTs
were chosen. The dimensions of this die are of
46cm width, 61cm length and 5cm height,
respectively. Several BIT/PZT IUTs were fabricatedonto the mold insert. The ultrasonic performance of
the IUT fabricated onto the surface is shown in Fig.
6. The 1st, 2nd, and 3rd reflected round-trip echoes
represented by L1, L2 and L3, respectively throughthe thickness of the die were clearly observed. The
center frequency. 6dB bandwidth and SNR of the L1
echo are 11.9MHz, 15.4MHz and 31dB,
respectively. It is believed that BIT/PZT IUTs are
suitable for process monitoring of thixomolding anddiecasting at the mold insert and the die.

Amplitude (arb. unit)

echo are 4.5MHz, 3.1MHz and 21dB, respectively.
It is noted that thermal cycling using the propane
gas torch as the heating source was executed 5
times between room temperature and 800°C and no
signal deterioration was observed. Since thetemperature at the nozzle of the thixomolding orthat of a diecasting machine is up to a maximum of
about 620°C, it is expected that LN/PZT IUTs are
attractive and practical non-invasive ultrasonicsensors for process monitoring at those locations.

0

5

10

15

20

25

Frequency (MHz)Fig. 6 Ultrasonic performance of BIT/PZT IUT
fabricated onto the surface of a thixomolding mold.

5.

15

20

25

Time Delay (μs)

30Fig.4 Transmission mode ofFig. 3 with oil at 200°C

BIT/PZT IUTs onto a mold insert

Filling completion monitoring has been
demonstrated in [1] using the invasive and bulky
delay line probes installed in the die. One objectiveof this study is to develop an on-site fabrication
technique to deposit the non-invasive and miniature
HT IUTs onto a large size metallic mold insert, e.g.
of thixomolding machine for process monitoring
purposes. It is noted that a large size mold insert has
huge thermal capacitance, it needs great care todevelop heating and cooling methods as well as
electric poling technique to treat the sol-gel

Conclusions

800°C LN/PZT [3] and 450°C BIT/PZTIUTs [2] were fabricated onto a titanium substrate
and a steel pipe, and a thixomolding mold insert,
respectively by a sol-gel spray technique suitablefor on-site fabrication. The ultrasonic measurement
results indicated that these IUTs are suitable forreal-time
non-invasive
ultrasonicprocessmonitoring at the nozzle and die of thixomolding
and die casting machines.
References
1. J.-F. Moisan, C.-K. Jen, J.-W. Liaw, C.-Q. Zheng,
T.-F. Chen, Z. Sun and C.A. Loong;
Measurement Science and Tech. 11 (2001) 1956.
2. M. Kobayashi, C.-K. Jen, Y. Ono, K.-T. Wu and I.
Shih: Jpn. J. Apl. Phys. 46 (2007) 4688-4692.
3. M. Kobayashi, H. Nagata, Y. Hiruma, T. Tokutsu,
T. Takenaka and C.-K. Jen: Proc. IEEE
Ultrasonics Symp (2007) 953.

2E2bProceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 179- 180
11-13 November, 2008

Imaging the Acoustic Rectification of Surface Acoustic Waves
音響整流器構造における表面音響波伝播の実時間イメージング*Sorasak Danworaphong1†, Timothy A. Kelf1, Osamu Matsuda1, Oliver B. Wright1,
Kosei Ueno2, Yoshiaki Nishijima2, Saulius Juodkazis2, and Hiroaki Misawa2(1Graduate School of Engineering, Hokkaido University, 2Research Institute forElectronic Science, Hokkaido University)*Sorasak Danworaphong1†, Timothy A. Kelf1, 松田 理 1, Oliver B. Wright1, 上野
貢生 1, 西島 喜明 2, サリウス ジュドゥカジス 2, 三澤 弘明 2
(1 北大院工; 2 北大電科研)

1. Introduction
Acoustic rectification is the process, analogous tothat used in diodes in electronics, in which acoustic
waves in a structure are preferentially transmitted in
one direction. Recently, acoustic rectifying
structures for bulk acoustic waves based on
triangular holes were proposed and numericallystudied by Krishnan et al.1,2 They used single anddouble rows of triangular holes on an elasticallyisotropic and homogeneous material. The
transmission
coefficients
andrectification
efficiencies of such waves were calculated, andcomparison between the single and double arrays
showed that the double arrays had better
efficiencies in general. The simulations also
indicated the existence of a threshold frequency
above which the rectification sets in. This was
explained as due to the Bragg diffraction of theacoustic waves, which also gives rise to periodic
frequency dips in the transmission and rectification
efficiency. Here we experimentally demonstrate
acoustic rectification at frequencies ~100 MHz-1
GHz for surface acoustic waves (SAW) on surfaces
containing rows of triangular holes.
We make use of an ultrafast imaging techniquethat combines a time-domain Sagnac interferometerwith the optical pump and probe technique.3,4
Temporal and spatial resolutions are ~1 ps and ~1
m,respectively.
Spatiotemporal
Fouriertransforms of the data allow the acoustic dispersion
relations to be derived, as well as the acoustic fields
in two dimensions at individual frequencies. This
allows the acoustic reflection and transmission
coefficients and rectification efficiencies to be
extracted.
2. Experiment
Micro-fabrication methods including lithography
and dry etching are used to make the rectifiersamples. The samples are fabricated on a silicon(100) wafer by plasma dry etching using a SF6 and*On leave from: School of Science, Walailak University
Nakhon Si Thammarat, Thailand 80160.

Fig. 1 SEM images of rectifier samples. a) Single row
structure and b) Double row structure.

C4F8 gas mixture and coated with polycrystalline
chromium film of thickness 30 nm. The depth of
the triangular holes is 11.3 µm, and the spacing is
20 µm. Fig. 1 shows the scanning electron
microscope (SEM) images of our single- anddouble-array rectifiers as well as their orientation
with respect to the Si crystal axes. The imaging
system is shown in Fig. 2. The pump (frequencydoubled at 415 nm) and probe pulses at 830 nm
originate from a mode-locked Ti:Sapphire laser at
75.5 MHz repetition rate and have a ~1 ps pulse
duration.
After modulation at 1 MHz by an acousto-optic
modulator, the pump beam is reshaped by acylindrical lens, and is then focused through a
microscope objective to create a line source oflength ~30 m for purposes of acoustic plane wave
generation. The aspect ratio of this line source is
10:1 and the average total power of the pump beam
after the objective lens is 5 mW. The line source ispositioned ~100 µm away from the rectifier
structure. Two optical probe pulses temporally
separated by 325 ps are focused onto the sample toa spot diameter of ~2 µm by the same objective
lens. The phase difference between the two probe
pulses, as measured by the Sagnac interferometer,
is detected by the use of two photodiodes. The
phase changes, caused by the outward motion of thesample ~10 pm in amplitude, are proportional to theFig. 2 Experimental setup.

outward surface velocity of the sample. The
differential output of these photodiodes is amplified
and fed to a lock-in amplifier synchronized to theoptical pump beam modulation frequency. The
scanned area of the sample covers a region of 80µm× 200 µm. A total of 48 images are taken foreach structure at equally spaced intervals in delay
time (between the pump and probe pulses) over theperiod (13.3 ns) between two consecutive pumppulses.
3. Results and Discussion
Figure 3 shows phase-change images at a fixed
delay time for the single-row sample of Fig. 1a) for
normal acoustic incidence on the single-row
structure from two different directions (termed I
and II as shown in the figure). The dispersion
curves for these two cases are obtained by spatiallyand temporally Fourier transforming the image data,
and are revealed by plotting the modulus of theFourier transforms in Fig. 4 in k space (where k is
the acoustic wave number in the vertical direction).
In Fig. 4a) the negative slope represents theincoming waves, which in this case are directed
towards the triangle bases (and move in thenegative vertical direction in Fig. 3). The fainterpositive slope represents the reflected waves. The
response for the transmitted waves overlaps herewith that of the incident waves. The positive slope
in Fig. 4b) represents incoming waves, which movein the positive vertical direction towards the tips ofthe triangles. The negative slope corresponds to thereflected waves.
The data of Fig. 4a) and 4b), representing theintensity of corresponding waves, are used toevaluate transmission and reflection coefficients,
including rectification efficiencies. Preliminary
results show a periodic response in frequency inboth single and double array structures, similar tothat predicted by Krishnan et al. However, there arecertain differences between the experiment and theFig. 3 Optical reflectance of the single row rectifier
structure: I and II indicate the direction of incident
SAW’s. a) and b) are the phase difference images atdelay time 0.51 ns for cases I and II, respectively. The
bright spot b) is the pump position.

Fig. 4 a) and b): modulus of spatiotemporal Fouriertransform for case I and case II, respectively, for the
single row structure.

theory due to the anisotropic nature of our silicon
substrate and the use of surface acoustic waves here
rather than bulk acoustic waves. Further modellingshould elucidate the differences.
Acknowledgement
The authors would like to express their gratitude
to N. Nishiguchi and Y. Tanaka for fruitful
discussions.
References
1. R. Krishnan, S. Shirota, Y. Tanaka, N.
Nishiguchi : Solid State Commun. 144 (2007)
194
2. S. Shirota, R. Krishnan, Y. Tanaka, N.
Nishiguchi : Jpn. J. Appl. Phys. 46 (2007)
L1025
3. T. Tachizaki, T. Muroya, O. Matsuda, Y.
Sugawara, D.H. Hurley, O.B. Wright : Rev. Sci.
Instrum. 77 (2006) 043713
4. Y. Sugawara, O.B. Wright, O. Matsuda, V.E.
Gusev : Ultrasonics 40 (2002) 55

2E2c

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 181- 182
11-13 November, 2008

Development of inspection equipment for bottom
edges of rails with guided waves
ガイド波によるレール底端部検査装置の開発
Junjie Chang†, Takahiro Hayashi, Morimasa Murase (Nagoya Inst. Tech.)
Keita Kataoka (East Japan Railway Company, Technical Center)
常俊傑‡，林高弘，村瀬守正（名工大），片岡慶太（JR 東日本）

2. Suitable modes for inspecting bottom edges
of a rail
Dispersion curves and wave structures for JIS
50kgN rail were obtained using our software basedon the SAFE method1-2) as shown in Figs.1 and 2.
Looking at the wave structures of modes in Fig.2,
we can find that these modes concentrate at thebottom edges and vibrate in both horizontal andvertical directions. Comparing vibration directionof the wave structures the horizontally vibrating
mode in Fig. 2 (a) can be expected that this mode
can avoid the interference with fastenings, and we
can conclude that this mode is the one of the most

5000

5000

4000

Group velocity (m/s)

Inspections for railway rails are now done by
an ultrasonic pulse echo method where transducers
on a rail inspection car input ultrasonic waves froma rail head with wheel probes. This technique isvery effective for inspecting defects in rail heads
and webs, but bottom edges of rails are blind zones
in this technique. Therefore, visual inspection iscarried out for bottom edges of rails except incrossings where the bottom edges of rails are
hidden by cover plates. Thus, the inspection
technique for bottom edges of rails, especially incrossings, is indispensable in order to ensure thereliability as well as safety of transportation.
On the other hand, the ultrasonic guided wave
technology attracts lots of attentions in recent years
because it can propagate along the bar-likestructures in the long distance. The “guided waves”
have been widely used as a fast screening technique
for such structures. And measurement of guided
wave propagation echo is a quite effective methodof NDE of bottom edge of rail.
This paper firstly describes the effective
guided wave modes for inspecting bottom edges ofa rail using guided wave dispersion curves softwaredeveloped by the authors1). A special angle beamtransducer for bottom edge inspection wasdeveloped. The developed transducer was checkedwith both the influences of fastenings and the defectinspection capability.

suitable modes for inspecting bottom edges of arail.
Group velocity (m/s)

1. Introduction

3000
2000
1000
0
0

4000
3000
2000
1000

20

40

60 80 100 120 140 160 180 200
Frequency (kHz)(a) horizontally dominant modes

0
0

20

40

60 80 100 120 140 160 180 200
Frequency (kHz)(b) vertically dominant modes

Fig.1 Group velocity dispersion curves at bottom edges
of a rail.

(a) horizontally vibrating mode(b) vertically vibrating mode

Fig.2 Visualization of the vibrating modes corresponding
to the arrow positions in Fig.1 (a) and (b).

3. Development of a transducer for bottomedge inspection
Since Rayleigh waves are generally excitedand received by an angle beam transducer, wefabricated an angle beam transducer consisting ofan epoxy resin wedge (longitudinal wave
cw=2500m/s) and a PZT disk (100 kHz). The
incident angle of the wedge is determined toapproximately 55˚ by Snell’ law for the phasevelocity of the Rayleigh-like mode , about 3000 m/s
at 100 kHz. The developed transducer for bottomedge inspection is shown in Fig.3.

Fig. 3 Transducer for a rail bottom edges.

Fig. 4 Configuration of a test plate and fastenings.
0Distance (m)
1.2
1.8

0.6

2.4

3

1600

2000

Three fastenings

Normalized Amplitude

Using the transducer, inspection experiments
for the bottom edges of a rail were conducted. The
configuration of the experiment is shown in Fig. 4.
In these experiments we use plates of 4.0m ×125mm × 12mm instead of real rails, because theRayleigh like mode propagates with vibrating onlyat the edges of the bottom plate like region. 6
fastenings were fastened about at every 60cm andthe plates are placed on the rubber plates on thesleepers. There were three fastenings (a) - (c)between the transducer and the defect. The otherthree fastenings were always fastened. The artificial
defect is located at 2.2m from the left end of theplates. Incident signals are a 10-cycle square burst
wave at the center frequency of 100 kHz.
First, the influence of the fastenings on thedefect echo was investigated using the developed
transducer. Figure 5 shows waveforms for various
fastening conditions. The upper horizontal axis
denotes distance between the transducer and a
defect calculated by the group velocity of theRayleigh-like mode 3000m/s.When fastenings (a) (c) were fastened in this order, waveforms wereobtained as shown from the bottom to top. The
upper horizontal axis denotes distance between thetransducer and a defect calculated by the groupvelocity of the Rayleigh-like mode 3000m/s. The
defect echoes were observed in all signals at thecorrect location, the overlapping waves at the left
end are reverberations within transducers andwithin epoxy resin wedge. As the number offastenings increases, the defect echoes become
smaller. This is because the plates and the sleepers
contact more tightly as the number of fastenings
increases and ultrasonic energy leak out and absorb
at the sleepers. Although the influence of fastenings
was observed in the signals, defect echoes are
sufficiently detected.
Next, in order to investigate the ability ofdefect detection using the developed technique,echoes from defects with various depths weredetected. The artificial defects are made by electric
saw with the depth from 2 mm to 10mm in 2 mmincrement. The width of the defect is about 2mm.
Fig. 6 shows the detected waveforms for various
depths of the defects. Although all fastenings were
fastened, the obvious echo was obtained from all
the defects at the correct locations calculated fromthe group velocity of 3000m/s. And the amplitudesof the echoes gradually increase for deeper defects.
The bigger waves at about 2.2m are from artificial
defects, and the small waves between reverberating
incident waves and defect echoes are fromfastenings.

Two fastenings
One fastening

No fastenings

0

400

800
1200
Time [ s]Fig. 5 Normalized amplitude with propagation
time for different fastenings.
0

0.4

0.8

Distance (m)
1.2
1.6
2.0

2.4

2.8

2mm defectNormalized Amplitude

4. Experimental result by developed transducer

4mm defect
6mm defect

8mm defect10mm defect

0

400

800
1200
Time [ s]

1600

2000

Fig. 6 Normalized amplitude with propagation time
for different defect order.

5. Conclusions
In this report, a transducer was designed byfollowing the analysis of mode selection and mode
excitation. In the experiments using the newly
designed transducer, the influences of fastenings
were investigated and defect inspection capabilityof the developed transducer was checked. Good
pulse echo signals were obtained with thetransducer at the correct location of a defect at abottom edge of rail.
References
1. T. Hayashi: Ultrasonics 41(2003) 175
2. T. Hayashi: Jpn. J. Appl. Phys. 47(2008) 3865.

2E4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 183- 184
11-13 November, 2008

Modeling of Thermoelastic Damping in Piezoelectric
Aluminum Nitride Tuning Forks
Gabriele Vigevani‡, Jan H. Kuypers and Albert P. Pisano(Berkeley Sensor & Actuator Center, University of California at Berkeley)

1. Introduction
The accuracy and performance of consumer
electronic devices is determined by theperformancesof
theirelectromechanicalcomponents, including
micrelectromechanicalsystems (MEMS) devices. A key to enhance theperformance of MEMS resonators is to increase the
Q and hence to minimize the impact of energy loss
mechanisms. Increasing the Q factor is also a key toimprove phase noise performances for frequency
reference and to improve the signal-to-noise ratio(SNR) for sensors.
The Q is the result of many energy losses ofdifferent origin and different magnitude. It istherefore extremely important to have accurate
design guidelines for each of the damping sourcesin order to minimize their impact. For beam based
resonators like a double ended tuning fork (DETF)
the air damping is usually the dominant energy loss
mechanism [1]. However, if these types ofresonators are operated in vacuum the ultimate Q islargely determined by thermo elastic damping(TED) [1].
There is an increasing interest in piezoelectric
actuation compared to electrostatic driven MEMS,
because of their better capacitance ratio (C0/Cm) andmore suitable impedances for interfacing withcircuits. For the first time the piezoelectric
contribution is included in the TED. Starting fromthe Euler Bernoulli theory for simple thermoelastic
beams developed by Lifshitz and Roukes [2] weconsider the piezoelectric constitutive equations andderive a closed-form expression for the Q-factor of
the beam. Because of its CMOS compatible
properties the following theory is applied toaluminum nitride (AlN), a piezoelectric andpyroelectric material of class 6mm.
2. Equations of Linear Thermo Piezo Elasticity
Beam Orientation
Consider a DETF of AlN with uniform
rectangular cross section and oriented as shown in
Fig. 1 with electrodes patterned on the top and thebottom surface. The strain of the in-plane
deformation along the x-axis (S11) leads to anelectric field along the z-direction via d31.

Fig.1 Illustration of the DETF orientation.
Divergence Gradient and Constitutive Equations
The physics of thermo piezo elastic
damping (TPED) are the result of the interaction of
three fields: A mechanical strain field, an electricfield and a temperature field. In order to study thebeam dynamics we must consider the divergenceand the gradient equations [3]. In addition to theseequations we have to consider the thermo piezo
elastic constitutive equations [4]:ΘS ij = α ijEθ + s Ejkl,ΘTkl + d mij
Ek

(1)

T ,Θ
Θ
Dn = p nT θ + d mkl
Tkl + ε nm
Em

(2)

⎛ ρC T , E ⎞⎟⎟θ + α ijE Tij + p mT E m⎝ Θ ⎠δσ = ⎜⎜(3)

where in (1) Sij is the strain, αij is the thermal
expansion coefficient, sijkl is the compliance tensor,
Tkl is the stress tensor, θ is the temperature
increment, dmij is the piezoelectric strain tensor and
Em is the electric field. In (2) pn is the pyroelectriccoefficient and εnm is the dielectric tensor. In (3) δσis the increment in entropy, ρ is the density and C is
the specific heat capacity and Θ is the reference
temperature.
Mechanical Domain: Euler Bernoulli Kinematics
The Euler Bernoulli theory considers only thestress in the axial direction (S11). According to theassumptions of the Euler Bernoulli kinematics, we
can write the following equation for the strain andthe balance of linear momentum [5]:
d 2Y
∂2M
∂ 2Y
(4)
,
− ρA ⋅ 2 = 0,
2
2
∂x
∂t
dx
Where Y is the mechanical displacement of theneutral axis, M is the moment of the beam, A is the
cross section of the beam and y is the distance of apoint from the beam neutral axis.
S11 = − yCombining (4) with the constitutive equation (1) we
get the following Euler Bernoulli formulation for apiezoelectric material:
αE ⎞∂ 2 ⎛ I M ∂ 2Y d 31
∂ 2Y
(5)
⎜
+
I E + 11 I T ⎟⎟ + ρA ⋅ 2 = 0,2 ⎜2∂x ⎝ s11 ∂x

s11

s11

⎠

∂t

where we define the following terms of inertia:∫∫

I M = y 2 dzdy ; I E = y ⋅ E3 dzdy ; I T =AAElectrical Domain∫ y ⋅ θ dzdy

d 2Y
+ Γ2θ ,dx 2

(9)where f1(ω) and f2(ω) are complex functions of thefrequency of vibration. The natural frequency of (8)is therefore given by:ω = (βL )2A

To derive the electrical domain equation wemust use the constitutive equation (2). If theelectrodes are short-circuited the piezoelectric
contribution is eliminated and the analyticalsolution coincides with the classic TED solution fora non-piezoelectric material [2]. If the electrodes
are not short circuited we set D3 = 0 [4], in this casethe electrical domain equation is given by:

E 3 = Γ1 y⎞
α11E
1 ⎛ d 31⎜⎜1 +Eω =f1 (ω ) +f 2 (ω ) ⎟⎟,s11 ⎝ I MIM⎠

I M Eω
,
ρAL4

(10)

where βL is a numerical value and depends on theboundary conditions at the ends of the beam [5].
The quality factor is given by [2]Q −1 = 2

Im(ω ).
Re(ω )

(11)

(6)

where
d
1
⎞
⎛d
1
⋅ 31 Γ2 = T ,Θ⋅ ⎜⎜ 31 α11 − p3T ⎟⎟22
ε33 − d31 s11 s11
ε33 − d31 s11 ⎝ s11⎠

Γ1 = T ,Θ

Thermal Domain
The thermal domain equation can be derived
by using the thermodynamic divergence andgradient equations and substituting the entropy
given by the constitutive equation (3). As in [2] we
can assume the following simplifications:-

For motion in the xy-plane: ∂θ = 0∂z- For low order mode of vibration: ∂θ >> ∂θ∂y∂x

Resulting in the thermodynamic equation:
∂E
∂θ
∂ 2θ
∂ ⎛ ∂ 2Y ⎞Δ1 = χ ⋅ 2 + Δ 2 3 + yΔ 3 ⎜⎜ 2 ⎟⎟, (7)∂t ⎝ ∂x ⎠
∂t
∂t
∂y
2
⎛
Θ α 11 ⎞⎟Δ 1 = ⎜⎜1 +T ,E
s11 ⎟⎠ρC⎝⎞
Θ α 11E
Θ ⎛ E d 31
⎜α
Δ3 =
Δ2 =
+ p3T ⎟⎟
T , E ⎜ 11
s11
ρC T , E s11
ρC ⎝⎠Results

Using harmonic ansatz functions for thetemperature θ, displacement Y and electric field Ein (5), (6) and (7) we obtain:

ω 2Y0 ( x) =I M Eω ∂ 4Y0 ( x)
,
ρA
∂x 4

In Fig.2 we plot the Q-factor as function of thebeam width for several natural frequencies.
Conclusion
Our results demonstrate the importance of
TPED as energy loss mechanism for miniatureresonators. The model shows that the piezoelectricand pyroelectric effects for a fixed-fixed beam
reduce the Q-factor by an amount of 15%.
Acknowledgment
This work was supported by DARPA
M/NEMS
S&T
Fundamentals
award(HR0011-06-1-0041) under the DARPA Center for
Micro/Nano Scaling-Induced Physics (MiNaSiP).

where:

3.

Fig.2 Inverse of Q as function of the beam width.

(8)

where Eω is an equivalent Young modulus for athermo piezoelectric material and has the following
form:

References
1. W.E. Newell: Science, 161 (1968), 1320.
2. R. Lifshitz and M.L. Roukes: Phys. Rev. B 61,(2000-II), 5600.
3. R. D. Mindlin: J. Solids Structures 10, 625.
4. T. Ikeda: Fundamentals of Piezoelectricity(Oxford Science Publications), 12.
5. Meirovitch: Fundamentals of Vibrations(McGraw Hill) 385.

2E5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 185- 186
11-13 November, 2008

Study on the Frequency Dependence of Lateral Energy
Leakage in RF BAW Device by Laser Probe System
Nan Wu†‡, Ken-ya Hashimoto, Keisuke Kashiwa, Tatsuya Omori,and Masatsune Yamaguchi (Graduate School of Engineering, Chiba University)
1. Introduction
A variety of laser probes have been applied to
the visualizaion of propagating surface and bulk
acoustic waves (SAW/BAW)[1-2]. The authors
have recently developed a phase-sensitive laser
probe system based on Sagnac interferometer forthe diagnosis of RF SAW/BAW devices[3]. Highquality 2D images of SAW/BAW field patterns canbe captured within several minutes. Currently thesystem operates at frequencies up to 2.5GHz[4-5].
The authors also developed integrated
software which can handle and processcomplex image data acquired by the
laser
probe
under
user-friendly
man-machine interface[6].
This paper describes theapplication of the developed hardware
and software to the diagnosis offrequency dependent energy leakage
occurring in RF BAW devices.

indicate the propagation of waves with different
lateral wavenumbers. The brightest center circle
corresponds to the thickness vibration of thelongitudinal wave.
Fig. 2(b) shows the result when only thesecond largest circle was extracted and inverse
Fourier transformed. It is seen that the wave energyof the mode leaks away under the upper electrodeof the resonator.
Fig. 2(a) and (c) show the results when thesame procedure was applied to the measured data at

2. Experimental Result(a) 1,790MHz(b) 1,816MHz(c) 1,840MHz
Fig. 1(a) shows a 2D image
Fig.2
Results
of
the
IFFT
after
the
extraction
obtained by the measurement at 1,816
MHz. In the RF BAW resonator used as
two different frequencies. From comparison of Figs.
a DUT, a piezoelectric AlN thin film is sandwiched
2(a) and (c) with Fig. 2(b), it is clearly seen that thein between two Ru electrodes, and the structure isenergy leakage is very frequency-dependent.
floating on a Si substrate through an air gap. The
transversal resonance pattern is clearly observed in
the oval region where the resonator is placed. Fig.
3. Analysis
1(b) shows the result of the 2D FFT of this image.
In the following analysis, three distinctive
Several concentric circles are seen. The circles
modes having a wavenumber represented by the
inner, second largest and outermost circles in the
FFT image in Fig. 1(b) are called Mode 1, Mode 2
and Mode 3, respectively.
Fig. 3 shows the dispersion relation between
the frequency f and normalised wavenumber βx/2π obtained by the scanned data at different
frequencies. The results are represented by “o”,“＊” and “+” for Mode 1, 2 and 3, respectively,
where the three corresponding lines are obtained by
the least squares method for the calculated results.
As can be seen from Fig. 3, Mode 1 possesses a
cut-off frequency around 1,825 MHz. The negative
group velocity of Mode 1 suggests that it is(a) Surface amplitude(b) Wavenumber domain
launched with a Poynting vector that is at someFig.1 Field distribution at 1,816MHz
angle off of the normal of the resonator surface

energy-trapped, main thickness vibration of thelongitudinal wave. Meanwhile, compare thebehaviours represented by the four lines. One cansee that the power of Mode 2 and 3 simply
decreases above 1,822 MHz. On the other hand, thepower of Mode 1 takes the maximum value at 1,822
MHz just below its cut-off frequency of 1,825 MHz.
The above discussion suggests that both Mode 2
and 3 may be excited by the reflection of Mode 1 at
the electrode edge. This concludes the reason why
the energy leakage can not be seen only in Fig.2(c).

Fig.3 Dispersion curve

which causes the displacement complexity[7].
For the energy leakage analysis, we also
calculate the power of each mode at some different
frequency points. For this estimation, first we get
the IFFT image of Mode 1, 2 or 3, and then sum up
the square of each pixel’s brightness.
Fig. 4 shows the relative power thus
estimated, where the three lines with “+”, “ × ” and“＊” represent the power of Mode 1, 2 and 3,
respectively. For comparison, the power of theoriginal amplitude image is shown by the line with“o”. Note here that the power of Mode 1 and theoriginal amplitude image is about 300 times larger
than that of Mode 2 and 3 (compare the right andleft vertical scales).
It can be seen very clearly that independentof frequency, most of the energy is contributed fromMode 1. This may confirm in conjunction with thediscussion in Fig. 3 that Mode 1 is substantially the

4. Conclusion
As an application of laser probe systems to
the diagnosis of acoustic wave devices, the paper
has discussed one of the mechanisms which cause
the lateral energy leakage encountered in RF BAW
device. It is suggested in the device used in theexperiment that the leakage may be caused by somespurious modes excited by the reflection of themain resonance mode at the electrode edge. The
conclusion has successfully explained theexperimental result for an RF BAW resonator.
Acknowledgment
The authors thank Mr. O. Takano, Mr. S. Meguro
and Mr. K. Akahane of Neoark Co., Ltd. for theirassistance to the system development. We also
thank to Fujitsu Laboratories for supplying thedevice used in the experiment. This work was partly
supported by the Mitsubishi Foundation, a Projectto Develop “Innovative Seeds” from the Japan
Science and Technology Agency, and a
Grant-in-Aid for Scientific Research from Japan
Society for the Promotion of Science.
References
1. S. Jen and C.S. Hartmann: Proc. IEEE Ultrason.
Symp. (1996) pp.33-36
2. H. Kamizuma, et al: Jpn. J. Appl. Phys. 44(2005) pp.4535-4538.
3. K. Hashimoto, et al: Proc. IEEE Micro. Symp.
(2008) pp.851-854
4. K. Kashiwa, et al: Jpn. J. Appl. Phys. 47, 5(2008) pp.4108-4110
5. K. Hashimoto, et al: IEEE Trans. Ultrason.,Ferroelec., and Freq. Contr. 53, 5 (2007)
pp.1072-1075
6. N. Wu, et al: IEEE Trans. Ultrason., Ferroelec.,and Freq. Contr., under review
7. R. C. Ruby, et al: Proc. IEEE Ultrason. Symp.
(2005) pp.1832-1835

Fig.4 Variation of relative power of each mode with frequency

2E3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 187- 188
11-13 November, 2008

Acousto-optic Characteristics of Silicon Nanofoam
シリコンナノフォームの音響光学特性
Takeshi Iino‡ and Kentaro Nakamura (P&I Lab., Tokyo Tech.)飯野剛‡，中村健太郎 （東工大 精研）

1. Introduction
Silicon nanofoam1 is porous material with
nano-meter structure produced through sol-gel
process, and has been used as heat insulator ofelectronic circuits. It is expected that the nanofoam
may work as a good acoustic matching layer ofairborne ultrasonic transducer for highly sensitive
and wideband ultrasound transmission/detection
since the nanofoam has an extremely low acoustic
impedance. The nanofoam may also have a
possibility as an acousto-optic device because of itsvery small sound speed and optical transparency.
We have measured the fundamental acoustic
and optical characteristics of the nanofoam throughacousto-optic measurements2,3. The sound speed
and the acoustic attenuation were measured in thefrequency range of around 500 kHz using
rectangular samples attached on a piezoelectrictransducer. Sound speed and acoustic attenuation
constant were 150~165 m/s and 2.78 dB/mm,
respectively. Optical refractive index and its change
rate due to sound pressure were measured at the
optical wavelength of 632.8 nm. Refractive index
was 1.075~1.080, and the change rate in therefractive index of nanofoam material due to soundpressure was 2.58~2.96×10-8 1/Pa. Opticalattenuation was 0.92 dB/mm for wavelength of
632.8 nm. Diffraction due to interaction between
light and ultrasound was also observed.

This time, among the acousto-optic
characteristics, we focus on the polarization rotationof the transmitted light due to sound pressure. First,
we investigate the effect of static force on the
direction of laser light transmitted through thesilicon nanofoam. Second, we measured modulationin the polarization of the transmitted light due toultrasonic wave.
2. Experimental set up
Figure 1 illustrates the set up for measuring
the polarization direction, where the direction ismeasured as an angle φ from the horizontal line.
Light source is a linearly polarized He-Ne laser.
The laser light goes through a half-wave plate, alight chopper, a silicon nanofoam sample, arotating-analyzer (polarization plate) and abiconvex lens. Intensity of the light is detected byan avalanche photodiode. The nanofoam sample isplaced on a bolt-clamped Langevin transducer andstatically loaded by 3.3 N. Polarization of theincident light is set parallel to the load direction
using the half-wave plate. Dimension of the silicon
nanofoam is 10 mm by 10 mm, and the thickness is
5 mm. Bolt-clamped Langevin transducer radiates a
26-kHz longitudinal wave traveling along thepolarization direction. The polarization direction of
the transmitted light is found by rotating theanalyzer.

Fig. 1 Experimental set up for measuring the rotation angle of polarization in
the laser light transmitted through a loaded silicon nanofom.

-----------------------------------------------------------iino.t.aa@m.titech.ac.jp

Experimental results

6.9N
4.1 N

300

0N
200

100

0

0

90

180

270

360

Angle of the analyzer [deg.]
Fig. 2 Light intensity vs. angle of the analyzer.
7
6
5
4
3
2
1
0
0

1

2

3

4

5

6

7

8

9

Static load [N]Fig. 3 Angle of the analyzer vs. static load.

Conclusions

Acknowledgment
Authors would like to thank Mr. M.
Hashimoto of Panasonic Corporation for providing
the silicon nanofoam sample.
References
1. H. Nagahara, T. Hashida, M. Suzuki and
M.Hashimoto: Jpn. J. Appl. Phys. 44 (2005)
4485.
2. T. Iino, K. Nakamura, S. Ueha: Proc. 19th ICA
2007 Madrid, (2007) ULT 02-003.
3. T. Iino, K. Nakamura, S. Ueha: Proc. Autumn
Meet. Acoust. Soc. Jpn., pp.1213-1214(2007.9)(In Japanese).

AC component of
the light intensity [arb.]

0.8

Polarization direction of the laser lighttransmitted through the nanofaom was changed bystatic load. We also observed the modulation in thepolarization angle due to 26-kHz ultrasoniclongitudinal waves.

180

0.6

90

0.4

0

0.2

-90

0.0

Phase [degree]

4.

400

Light intensity [arb.]

Figure 2 shows the light intensity detected by
the APD as a function of the angle of the analyzer
for different static load without ultrasonic excitation.
Here, the lock-in detection was carried out using the
chopper to measure the transmitted light intensity.
The polarization direction of the laser light was
rotated by the static load by several degrees. The
relationship between the rotation angle of thepolarization and the applied static force issummarized in Fig. 3. In this case, the polarizationis rotated by 1.0 degrees by the load of 1 N in the
middle of the curve.
Next, the 26-kHz vibration is added to thestatic force of 3.3 N, and the AC (26 kHz)component was measured for different angles of theanalyzer. Here, the lock-in detection was made withthe driving signal of the transducer as a reference
signal. Figure 4 shows the intensity and phase of
the AC component of the transmitted laser light.
Intensity had local maximal values at 45 degrees,
135 degrees, 225 degrees and 315 degrees, because
the slope of Fig. 2 was maximum at around theseangles. There was a 180-degree phase difference
between adjacent peaks in Fig. 4 because the signof the slope was changed at 0 degrees, 90 degrees,
180 degrees and 270 degrees. If we observe theresults carefully, we shall find that the peaks and thenulls in Fig. 4 are shifted by 2 degrees due to theoffset caused by the static force of 3.3 N.

Angle of the analyzer [deg.]

3.

-180
0

90

180

270

360

Angle of the analyzer [deg.]

Fig. 4 Intensity and phase of the AC componentof the laser light vs. the angle of the analyzer when
26-kHz sound wave is applied.

2E6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 189- 190
11-13 November, 2008

The Influence of Liquid Height on the Ultrasonic Power
Dissipated in Organic Solvents
Maricela Toma１, Satoshi Fukutomi１, Yoshiyuki Asakura2, Shinobu Koda１
１
Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan,
2
Honda Electronics Co., Ltd., 20 Oyamazuka, Oiwa-cho, Toyohashi, Aichi, Japan

1. Introduction
It is well known that the intensity of cavitational
phenomenon depends on the acoustic pressure
generated in the sonochemical reactor vessel.
Although the literature is abundant in the reports
about the dissipated ultrasonic power only few
studies on organic solvent have been reported (1, 2),
most of the measurements have been performed forwater. Measuring the ‘‘true’’ sonochemical powerin the fluid is of great importance for understanding
and improving the efficiency of the sonochemical
reactors. Thus, for a better description of the energybalance our study focuses on the accuratequantification of ultrasonic power dissipated on asonochemical reactor operating at an ultrasonicfrequency of 490 kHz.
2. Method and materials
The ultrasonic power dissipated in the bulk liquid
were investigated as a function of the liquid height
for a cylindrical vessel cell (60mm diameter) when
the liquid column ranges from 3 to 30 cm and theresults were compared for different organic solvents.
In order to obtain accurate data, the electrical power
input at the transducer is constant for all
measurements. The experimental set-up is shown in
Fig.1.

The ultrasonic power dissipated in the bulk liquid
was measured by calorimetry for water and for thefollowing organic solvents: methane, ethanol,
buthanol, propanol, cyclohexane, hexane, benzene,
toluene, xilene and 1,2,3,4-tetrahydronaphthalene(tetralin). All solvents employed in this work wereof high purity (99,5%) and used as purchased
without any purification step. Prior to every
experimental measurement the solvents weresaturated with air at atmospheric pressure. The
dissipated power quantities were recorded
calorimetrically at half height of the liquid column
with a thermocouple (T-type). The effective power
input into the oscillator is regulated at a fixed valueof 30W as measured with an oscilloscope, type
TDS300B; Tektronix. Measurements were carriedout at an initial temperature of 298K and thedissipated power was calculated by the following
equation: Power= M.Cp.dT/dt, were Cp is the heat
capacity of the liquid, M is the mass of liquid anddT/dt is the rate of increased temperature.

3. Results
The dependency of the energy conversion ontemperature for different solvents is presented
Fig.2.

38

Function Generator
WF1944

Oscillator

Temperature [℃]

Thermometer

Water
Ethanol
Propanol
Butanol
HexaneCyclohexane
BenzeneTolueneXyleneTetralin

36

PC

Thermocouple

34
32
30
28

⊿T０
⊿T

26
Transducer
490 kHzPower Amplifier
L400BM-H

Fig. 1 Experimental set-up for power
measurements.
-----------------------------------------------------------e-mail address: toma@nuce.nagoya-u.ac.jp

⊿T０

24
-50

U p = CP M

⊿ｔ

0

50
100
Time [s]

150

∆T
∆t

200

Fig. 2 The energy conversion for different
solvents.

35

Ultrasonic power, W

30
25
20
15

Ethanol
Tetralin
TolueneCyclohexane
Water

10
5
0
0

5

10

15

20

25

30

35

Height, cm
Fig. 3. Dissipated ultrasonic power as a function of the liquid height.
Fig.3 shows the dependence of dissipatedultrasonic power on the height of the liquid for
different solvents. The data presented in the Fig.2
illustrates that the type of organic solvent is an
important parameter in the energy conversion
process. The details will be discussed in ourpresentation. For the presented experimental
conditions, the efficiency of the sonochemical
reactor increases with the increasing of the liquidcolumn height, as shown in Fig.3. Based on theliterature reports, it is expected that the acoustic
power input increases with the increasing of theliquid height (1). By increasing of the liquid column
height from 3 to 30 cm, the volume of sonicatedsamples is increasing by 10 times for the lastexperimental value presented here. It is meaningful
to indicate that with the increasing of the liquidheight, the buoyancy of cavitation bubbles and themagnitude of the bubble coalescence increases as
well, this phenomenon reduces the number ofcavitations and therefore the slope of thecalorimetric curve. It was noticed that the intensityof the solvent evaporation and mist formation
decreases dramatically as the liquid height increases
up to 14-15 cm.

4. Conclusions
The intricate coupling

between the ultrasoundsource and the sonicated liquids generated a lack of
accurate reports regarding the dissipated ultrasonicpower. In this study, calorimetry has been

employed to describe the influence of liquidheight on the ultrasonic power dissipated on thevessel of a sonochemical reactor operating at afrequency of 490 kHz and the data werecompared for different organic solvents in an
attempt to define the power conversion basis
for scale-up considerations. Based on this data, it
is reasonable to conclude that the efficiency of the
490 kHz sonochemical reactor increases as theliquid height increases, mainly due to the thermal
effect (associated with cavitational phenomenon)
diminution.
References
1. M.W.A. Kuijpers, M. F. Kemmere, J. T. F.
Keurentjes : Ultrasonics 40 (2002) 657.
2. Jan-Martin Loninget, C. Horst、U. Hoffmann:
Ultrasonic Sonochemistry 9 (2002) 169.

2E8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 191- 192
11-13 November, 2008

Heat Pump Placed in the Resonance Tube Connected to the
Loop-tube-type Thermoacoustic Cooling System Improves the
Cooling Effect
ループ管に接続した共鳴管内にヒートポンプを設置することによる冷却効果の向上
Shin-ichi SAKAMOTO1†, Hideo YOSHIDA2, Atsushi Sakaguchi3, and Yoshiaki
WATANABE4 (1University of Shiga Prefecture; 2, 3, 4Doshisha University)†

坂本眞一 1 ，吉田秀穂 2，坂口敦 3，渡辺好章 4（1 滋賀県立大学;

2, 3, 4

同志社大学）

Pressure gauge

1. Introduction
K-type Thermocouple
Thermoacoustic effect enables mutual energy
conversion between heat energy and sound energy.
P_ch2:
Practical application of the "thermoacoustic cooling
1.02 msystems" using such energy conversion creates an
P_ch1:
eco-friendly cooling system that enables the
0.45 meffective use of energy. Today, the study ofthermoacoustic cooling systems is progressing
energetically in every corner of the earth1-5). Ourgroup is also conducting research to improve thecooling effect of a loop-tube-type thermoacoustic
cooling system6-8).
We discuss the cooling effect of a loop-tube-type Pressure gauge
thermoacoustic
coolingsystemespeciallyemphasizing the effect of the heat pump placed in K-type Thermocouple
the resonance tube, while making the tube resonate
at one-wavelength mode.
P_ch2:
1.02 mReference-temperature
heat exchanger

P_ch3: 1.72 m
P_ch4: 1.92 m

Stack
Cooling point
Heat pump

T_ch:

Prime mover
High-temperature
heat exchanger
Stack
Reference-temperature
heat exchanger

P_ch5:
2.37 m
P_ch6:
2.94 mLoop tube A

Reference-temperature
heat exchanger

P_ch3: 1.72 m
P_ch4: 1.92 m
Stack

Cooling point
Heat pump
2. Experiment Setups
P_ch1:
0.45 mT_ch:Three types of loop tube are used: loop tubes A,
Prime mover
B, and C. Loop tube A is not connected by the
P_ch5:
High-temperature
2.37 mheat exchanger
resonance tube and the heat pump is placed upper
Stackright in the loop. Loop tube B is connected by the
P_ch6:
Reference-temperature
2.94 mheat exchanger
resonance tube and the heat pump is placed in theresonance tube. Loop tube C is connected by the Pressure gauge
Loop tube B
resonance tube and the heat pump is placed upper
right in the loop. Figures 1(a) – (c) show schematic K-type Thermocouple
P_ch3: 1.72 m
illustrations and the experiment setups of loop tubes
P_ch4: 1.92 m
Reference-temperature
P_ch2:
heat exchanger
A, B, and C. The total length of the loop except for1.02 mStack
the resonance tube is 3740 mm. The inner diameter
Cooling point
P_ch1:of the tube is 42.5 mm. Air is filled in the loop tube
Heat pump
T_ch:0.45 mat atmospheric pressure as the working fluid. The
Prime mover
P_ch5:
High-temperature
50 mm long honeycomb-ceramic stack with the2.37 mheat exchanger
channel radius of 0.45 mm is used in the prime
Stack
P_ch6:
Reference-temperature
mover and that with channel radius of 0.35 mm is
2.94 mheat exchanger
used in the heat pump. The resonance tube is
Loop tube C
connected to the upper right portion of loop tubes B
Fig.1 Schematic illustrations and theand C, which is near the antinode of the soundexperiment setups of loop tubes A, B, and C.
pressure. The tube is 935 mm in length which is a

4. Summary
We discuss the cooling effect of a loop-tube-type
thermoacoustic
coolingsystemespeciallyemphasizing the effect of the heat pump placed in
the resonance tube. The temperature decrease forthe loop tube connected by the resonance tube withthe heat pump placed in the resonance tube is 25 °C,
while the temperature decrease for the loop tube
without the resonance tube with the heat pumpplaced in the loop tube is only 9 °C. This is theeffect of the heat pump placed in the resonance tube.
The heat pump placed outside of the loop tube
suppresses an influence of not only the viscosity
effect of the heat-pump stack but also theundesirable heat flow caused by the acoustic
streaming. According to this, the connection of theTemperature decrease [deg C]

30

Loop tube A
Loop tube B
Loop tube C

25
20
15
10
5
0
0

50

100 150 200 250
Input heat energy [W]

300

350

Fig.2 Temperature decrease at the coolingpoint measured for various input heat energy.
1.6x104

Loop tube A
Loop tube B
Loop tube C

1.4
2

3. Results
The temperature decrease at the cooling point
measured for various input heat energy is shown in
Fig. 2. The temperature decrease for loop tube B is
the biggest, and those for loop tubes C and A follow.
In the case of input heat energy of 330 W, thetemperature decrease for loop tube B isapproximately 25 °C, while the temperature
decrease for loop tube A is only about 9 °C and thatfor loop tube C is about 11°C.
Figure 3 show the sound intensity distribution forloop tubes A, B, and C. The values in these figures
are calculated using the two-sensor power method3),
based on the observed sound pressures obtained by
the pressure gauges.
The sound intensity for loop tube A between
P_ch1 and P_ch2 is 310 W/m2, that for loop tube B
is 11300 W/m2, and that for loop tube C is 1050
W/m2. The sound intensity shows the efficiency ofheat-to-sound energy conversion. The bigger thesound intensity, the more efficiently the heat energy
is converted to the sound energy. Since the soundintensity for loop tube B is the biggest, theheat-to-sound energy conversion efficiency for loop
tube B is the highest, and consequently, the cooling
effect for loop tube B is the greatest.

resonance tube contributes to an improvement.
Consequently, the heat pump placed in theresonance tube connected to the loop tube improves
the cooling effect of the loop tube.

Intensity [W/m]quarter of the total length of the loop tube. One endof the tube is open.
The temperature at the cooling point of the heatpump is measured with K-type thermocouple. The
sound pressure of the sound generated in the loop
tube is measured using six pressure gauges. The
measurement is conducted changing the input
power of heat energy supplied to the electric heaterfrom 50 W to 330 W for three loop tubes A, B, and
C.

1.2
1.0
0.8
0.6
0.4
0.2
0
0

500

1000 1500 2000 2500 3000

Distance from the heater [mm]Fig.3 Sound pressure distribution in the caseof input heat energy of 330 W for loop tubes
A, B, and C.
References
1. T. Yazaki, A. Iwata, T. Maekawa, and A.
Tominaga: Phys. Rev. Lett. 81 (1998) 3128.
2. S. Backhaus and G. W. Swift: Nature 339(1999) 335.
3. T. Biwa, Y. Ueda, T. Yazaki, and U. Mizutani:
Cryogenics 41 (2001) 305.
4. T. Yazaki, T. Biwa, and A. Tominaga: Appl.
Phys. Lett. 80 (2002) 157.
5. Y. Ueda, T. Biwa, U. Mizutani, and T. Yazaki: J.
Acoust. Soc. Am. 115 (2004) 1134
6. S. Sakamoto and Y. Watanabe: Jpn. J. Appl.
Phys. 43 (2004) 2751.
7. S. Sakamoto and Y. Watanabe: Acoust. Sci.
Technol. 27 (2006) 361.
8. H. Yoshida, S. Sakamoto, and Y. Watanabe: Jpn.
J. Appl. Phys. 46 (2007) 4413.

2E9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 193- 194
11-13 November, 2008

A Study on SSBL Underwater Positioning Using SS
Communication
SS 信号を用いた SSBL 水中音響測位に関する研究
Yoshitaka Watanabe1†, Hiroshi Ochi1, Takuya Shimura1 and Takehito Hattori2(1 Mari-tech., JAMSTEC.; 2NME.)
渡邊佳孝 1‡，越智寛 1，志村拓也 1, 服部岳人 2 （1 海洋機構; 2 日海事）

1. Introduction

250

250

200

200

150

150

X [m]

X [m]

In recent years precious observations withautonomous underwater vehicle (AUV) have been
carried out. The positioning and navigation of AUV
is very important. However in acoustic positioningof underwater vehicles as AUV, state of target
varies from hour to hour. The Authors are studyingof acoustic positioning with communication in thatcase. The studies of integration of acoustic
positioning and inertial navigation system (INS) arebeing performed in the world1. In this paper an
integration method are shown. In the method the
support ship monitored the AUV with super shortbaseline (SSBL) acoustic positioning. INS output
data are included in the response signal from AUV.
The support ship equips a hydrophones array for
SSBL and receives the signal. Simulation andexperimental results are shown and the cause oferror is considered in this paper.

Table1. Parameters of signal from AUV
Carrier frequency
12.5kHz
Chip rate
3.125kHzPN codeM-sequence, length=31
Data modulation
8PSK
Fractional sampling rate 2
Symbols per INS data
NI =20Array allocation
4x4=16ch planer array

100
50
0
-100

50

-50

0

50

100

0
-100

150

æ
æ
1
δx (m) - δx (m - 1) ö ö÷÷÷
å ç xa (mN I - l ) - çç δx I (m - 1) + ( N I - l ) I N I÷N I l = 0 çè
I
è
øø

.
= x 0 (m ) + n
where x0 : the origin during the continuous signal,
xa : the SSBL estimation of absolute position of
AUV, δxI : relative position to origin obtained
from INS output and n : random error due to SSBL.
x0 is calculated by a Kalman filtering. The detail isreferred in ref. 2. And the absolute position of AUV
xAUV is calculated asx AUV ( m ) = x 0 ( m ) + δx I ( m ).
Fig.1 shows a simulation result. The left
shows SSBL estimation. The right shows the result
calculated with the method mentioned above. The-----------------------------------------------------------yoshitakaw@jamstec.go.jp

0

50

100

150

Y [m]

(a) SSBL estimation.
(b) Proposed method
Fig. 1 Simulation result of AUV positioning. The
true track is well tracked in the right figure.
100

N -1

-50

Y [m]

100

2. A method of AUV positioning
50

50

X [m]

X [m]

In this method the response signal from AUV
is continuous which length is few or few dozen
seconds. The INS data output in the AUV are
included in the signal. Phase shift keying (PSK) is
used as the data modulation. And the spread
spectrum (SS) technique is applied. The parametersof the signal from AUV are shown in Table 1. The
relationship of SSBL and INS outputs is shown as

100

0

-50

-100
-100

0

-50

-50

0
Y [m]

50

100

-100
-100

-50

0
Y [m]

50

100

(a) SSBL estimation.
(b) Proposed method
Fig. 2 An ocean experimental result. The signal wastransmitted
Px (m) = Px - ( mfrom) - Kmoored( m + 1)device
Px - ( mto) the ship.

true track of AUV, starting from the left low to theright upper, is well tracked in Fig.1. And Fig.2
shows an experimental result. The experiment was
implemented in the deep ocean. The depth wasaround 1,000 meters. The acoustic signal wastransmitted from the experimental device mooredon the sea bottom. And the signal was received thehydrophones array equipped on the ship. The
horizontal range between the ship and theexperimental device was around 1,400 meters. The
right figure is result applied our method. The
estimation is well converged. In the both the results
calculated with proposed method were clearly
better than simple Kalman filtering using only
SSBL estimations2.

4.

Summary

An integration method of SSBL and INS was
introduced. Simulation and experimental results
were shown and it was shown that the method

Error of arrival angle estimation [rad]Vp=-8m/s

0.02
Vp=-5m/s

0.01

Vp =-2m/s

0 V =2m/s
p-0.01 Vp=5m/s-0.02-0.03 V =8m/s
p
-0.04
10

20

30

40
50
60
Arrival angle [deg]

70

80

90

Fig. 3 Error of arrival angle estimation due to the
Doppler shift caused by the motion of the array.
1

Amplitude

0.8
0.6
0.4
0.2
0

0

Fig. 4

0.2

0.4

0.6
0.8
Time [sec]1

1.2

Propagation channel of the signal of theexperiment.

200

X [m]

The acoustic signal for positioning is
distorted and the estimation of SSBL is degraded.
The causes are considered as noise, Doppler shift
and interference due to multipath.
The SSBL estimation is achieved with themean described in ref. 1. The arrival direction of
signal is calculated with phase differences of all
combinations of the array elements. If the array isthree dimensional, the effect of Doppler shift isnegated. On the other hand if the array is twodimensional as planer array in this paper, theDoppler shift degrades the estimation result. Fig.3
shows the error of estimation arrival angle due toDoppler shift generated at relative velocity Vp.
When the arrival angle is 30 degrees and Vp is 5
m/s, systematic error of few percents of the slant
range is generated. This is lower than other errors.
And the degree of error can be estimate with thephase rotation of the signal and AUV speed from
INS data. The phase rotation includes both motionsof ship and AUV, so the AUV speed is necessary.
The acoustic signal is continuous in this study.
When the signal is short pulse, the multipath is notconsiderable. However in the case as this study, themultipathe becomes a cause of the SSBL estimation
error. The arrival directions of the reflection waves
from frames are close to that of direct wave. Thenthe interference is also close for each other element.
However for example the arrival direction of thereflection from the sea bottom is obviously different
from that of direct wave. Then the SSBL estimation
is degraded due to the interference. Fig. 4 shows the
propagation channel in the experiment of Fig. 2.
Multipath exists close behind the direct wave. Thisis seems to be the reflection from the seabed. Andaround one second after some multipaths exist.
These seem to reflect twice at the surface and theseabed. Fig. 5 shows the each axis output of the
SSBL estimation result of Fig.2. It can be found thatthe variation of output becomes larger at around100th symbol. This can be guessed to be theinterference of the multipaths with twice reflection
mentioned above. Although the levels of themultipaths are low, the arrival angle is far different
from that of the direct wave. Then the influence of
the interference is high. This is the inter-symbolinterference (ISI) and the error degrees are different
between each interfering symbol. If the symbol
sequence is enough random, the error can becompensate with the Kalman filter shown as Fig.2.

0.03

100
0

0

50

100

150

200

250

300

350

400

0

50

100

150

200

250

300

350

400

50

100

150

200

250

300

350

400

100

Y [m]

Error due to signal distortion

0
-100
1200

Z [m]

3.

1000
800

0

Fig. 5

Outputs of each axis of SSBL estimation.

works well. The estimation errors due to the signal
distortion caused the Doppler shift and the ISI wereconsidered. Especially the error of SSBL estimation
due to the ISI is generated because of thecontinuous acoustic signal that is distinguished forthe proposed method. Nevertheless the proposed
method is useful.
In the future adaptive compensation of thesystem error and multiple access will be considered.
Acknowledgment
The ocean experiment was supported by the crewsof R/V KAIYO and the support members of Marin
Works Japan.
References
1. M. Morgado, P. Oliveira, C. Silvester and J. F.
Vasconcelbs: The 9th International Conferenceon Information Fusion (2006).
2. Y. Watanabe, H. Ochi. T. Shimura and T. Hattori:
IEEE/MTS OCEANS2008, Quebec (2008).

2P1-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 195- 196
11-13 November, 2008

Elastic properties of polymorphic protein crystals
studied by micro-Brillouin scattering
顕微ブリルアン散乱法によるタンパク質結晶多形の音波物性
Yuichiro Aoki†, Eiji Hashimoto, Hitoshi Kanazawa, Yuji Ike, Seiji Kojima(Univ. Tsukuba, PAS.)†

青木雄一郎 ，橋本英二，金沢一史, 池祐治, 小島誠治 （筑波大 数理物質）

1. Introduction
To clarify physical properties of protein crystals
are important in various fields, such as biology,
pharmacology, and engineering. The protein crystal
has a polymorph1, and they have different physicalproperties.
The micro-Brillouin scattering is the bestsolution for the measurement of a small sample bynoncontact and nondestructive, and to measure thesample like the protein crystal. Since protein
crystals contain a large amount of water molecules,
the crystals may deform and damage during thedehydration such as, unwanted stresses, cracks,
degradations in mosaicity etc. The Brillouinscattering measurement enables us to determine thesound velocity, elastic constant and damping ofsound waves.
We employed glass forming liquid of
ethylene-glycerol and glycerol which undergoes a
glass transition without crystallization even in slow
cooling. Glass transition phenomenon is related tocluster structure formed by hydrogen bond.
By micro-Brillouin scattering over a wide
temperature range, we can discuss behavior ofintermolecular water and glass transition.
2. Experimental
The experimental setup of a micro-Brillouinscattering instrument is shown Fig. 1. The Brillouinscattering spectra were measured at the backward
scattering geometry. The Sandercock-type 3 + 3
pass tandem Fabry-Perot Interferometer (FPI) was
combined with microscope and operated to acquire
spectra of scattered light. A free spectral range of 30
GHz was applied and the Brillouin spectra were
measured in ± 25 GHz frequency range. The
sample temperature was controlled within ± 0.1 oC
and increased from room temperature with acryogenic cell (LINKAM HTMS600).
-----------------------------------------------------------e-mail address: s-aokiy@ims.tsukuba.ac.jp

SINGLE FREQUENCYLASER (532 nm)
PM：PhotomultiplierCCD
CAMERA

M1
L2
m3

PM

FPI1
L1

Incident
beam

FPI2

m2

Scattered
light

m1

SampleM3

M2

Objective
lens

Microscope

FPI. Scan.
Controller

Photon counterFig. 1 Schematic diagram of the micro-Brillouinscattering instrument2.

_
110

110

101
Fig. 2 The as-grown tetragonal HEWL crystal with habit
planes of {110} and {101}.

Hen egg white lysozyme (HEWL) crystals weregrown by two liquids interface method that
employing an insoluble and dense liquid.3 Crystals
were grown on the interface of two liquids oflysozyme solution and dense liquid such as
Fluorinate. We made the lysozyme crystals of
tetragonal crystal, monoclinic crystal, and,orthorhombic crystal. For example, the solution to
make tetragonal crystal were consisted of 25 mg/ml
lysozyme and 5 % (w/v) NaCl in 50 mM acetate
buffer solution (pH = 4.5). All crystals were grownin few days and show the crystal habit of {110} and{101} planes. The micrograph of as-grown crystal
was shown in Fig. 2. The laser beam was incident
perpendicular to the {110} habit plane of thecrystal.

Scientists, 18·3811.

1.0

25°C
60°C
-80°C
-180°C

4. Summary
By using the micro-Brillouin scattering method,
we successfully observe the temperaturedependence of Brillouin shift and FWHM in HEWL
crystals. We observe glass transition of the protein
crystal and alcohol solution. The relaxation process
originate from cooperative motion is clearlyobserved.
The comparison of the relaxation processes ofthree kinds of HEWL crystal will be discussed.
Acknowledgments
This research was partially supported by the
Ministry of Education, Science, Sports and Culture,
Grant-in-Aid for Exploratory Research, 19656005,
2007 and the Research Foundation of the Japan
Society for the Promotion of Science for Young

0.8
0.6
0.4
0.2
0.0
-30

-20

-10

0

10

20

30

Brillouin shift (GHz)

Fig. 3 Observed Brillouin spectra of a HEWL crystal at
25℃(line), 60℃(broken line), -80℃(dotted line), -180℃(chain line), which include the scattering from thelongitudinal acoustic phonon.

10

Brillouin shift (GHz)

22
20

shift

18

FWHM

9
8

16

7

14

6

12

5

10
8

4

6

3

4

2

2

1

0
-200

-150

-100

-50

0

50

100

150

FWHM (GHz)The observed Brillouin spectrum of a HEWL
crystal shows one broad longitudinal acoustic (LA)mode as shown in Fig. 3. As temperature decreases,
Brillouin shift increases and full width at half
maximum (FWHM) gradually becomes narrow.
Brillouin shift and FWHM were determined fromthe spectra. The longitudinal sound velocity wascalculated from the Brillouin shift ν (= qVl/2π) andthe scattering wave vector q (= 2πnsin(θ/2)/λ),where n, λ and θ are the values of refractive index
of the sample, the wavelength of the laser andscattering angle, respectively. The value ofrefractive index of a HEWL crystal5 was used. The
LA mode absorption coefficient α is related to
FWHM of Brillouin component by the equation, α= πΓ/Vl where Γ is FWHM. The temperaturedependence of Brillouin shift and FWHM is plotted
as shown in Fig. 4. It shows FWHM peak at about
80 °C. The glass transition occurs at the kink pointat about -100 °C. At the high and low temperature,
Brillouin shift and FWHM gradually approach theconstant value. The behavior of relaxation process
is observed when the solution surrounding a crystal
vitrified.
From the results, we can discuss the structural
relaxation process based on viscoerastic theory. The
Brillouin data analyzed by using a Debye function,
and, the activation energy is obtained. The
relaxation process is relevant to the cooperative
motion of alcohol, protein, and, water molecules.

Intensity (arb. units)

3. Results and Discussion

0200

Temperature (°C)

Fig. 4 Temperature dependences of Brillouin shift and
FWHM of a glycerol solution (65 mol %).

References
1. M. C. R. Heijna, W. J. P. van Enckevort, and E.
Vlieg: Cryst. Growth Des., 8 (2008) 270.
2. Y. Ike and S. Kojima: J. Aco. Soc. Jpn. 61 (2005)
461. (in Japanese)
3. H. Adachi, T. Watanabe, M. Yoshimura, Y. Mori
and T. Sasaki: Jpn. J. Appl. Phys. 41 (2002) L
726.
4. B. Cervelle, F. Cesbron, J. Berthou and P. Jolles:
Acta Cryst. A30 (1974) 645.
5. E. Hashimoto, Y. Aoki, Y. Seshimo, K. Sasanuma,
Y. Ike and S. Kojima: Jpn. J. Appl. Phys. 47(2008) 3839.
6. K. Sasanuma, Y. Seshimo, E. Hashimoto, Y. Ike
and S. Kojima: Jpn. J. Appl. Phys. 47 (2008)3843.

2P1-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 197- 198
11-13 November, 2008

Elastic Properties of Potassium Borate Glasses in a
Wide Composition Range Studied by Brillouin
Scattering
ブリルアン散乱による広い濃度範囲のカリウムホウ酸
塩ガラスの弾性的性質
Mitsuru Kawashima1, †, Yu Matsuda1, Yasuteru Fukawa1, Seiichi Mamiya1,
Masao Kodama2 and Seiji Kojima1 1(Univ. Tsukuba, Inst. Mat. Sci.) 2(Sojo
Univ., Dept. Appl. Chem. )†川島充 1, ，松田裕 1，布川泰輝 1, 間宮精一 1, 小玉正雄 2, 小島誠治 1
理物質）2（崇城大 応用化学）

1. Introduction
The structure and physical properties of alkali
metal borate glasses show the anomalous behavior
against their composition, such as exhibiting
maxima or minima.
The elastic properties of sound velocity andelastic moduli are very sensitive and indicative of
the change of the glass structures, therefore it isinteresting to investigate the composition
dependence of the elastic properties of thepotassium borate glass (KB) system. In this context,
the composition dependences of the elastic
properties of KB are of great interest. We alreadyreported the composition dependence of the elastic
properties of KB up to 34 mol% of K2O studied by
the ultrasonic pulse-echo overlap method [1]. The
present paper is a sequel of our previous studies[1-2]. Since the glass-forming ability of the highcomposition samples is poor, the only thin andfragile samples are obtained. It is impossible toperform the ultrasonic pulse-echo overlap method
using a transducer. The Brillouin spectroscopy is a
powerful tool to investigate the elastic properties ofglass of the high composition KB.
2. Experimental
The composition formula of potassium borate
glasses is denoted by xK2O･(100-x)B2O3, where x
is molar composition of K2O. All glasses wereprepared with high homogeneity in order toinvestigate the inherent nature of binary system [1].
To achieve the high homogeneity of the glass
forming materials, they were first made to react inan aqueous solution. The compositions of all
glasses were analyzed with respect to both x and(100-x) with a neutralization titration [1].
-----------------------------------------------------------The corresponding author: s-kawa@ims.tsukuba.ac.jp

1（筑波大 数

Fig. 1 Schematic diagram of the micro-Brillouinscattering apparatus.

The experimental setup of a Brillouin scattering
apparatus is shown in Fig. 1. The features of thissystem are a combination of a microscope and a
Sandercock-type 3 + 3 passes tandem multipass
Fabry-Perot interferometer (FPI) [2]. The Brillouinscattering spectra were measured at a backward
scattering geometry.
3. Results and Discussion
In order to measure not only transverse acoustic(TA) mode but a longitudinal acoustic (LA) mode,
the Brillouin scattering spectra were measured at
the right-angle (90oA) scattering geometry. Figure 2
shows the observe Brillouin spectra of KB. The
Brillouin shifts (Δν) and the full width half
maximum (FWHM) have been obtained from thefitting procedure of the spectra.
The LA velocity (VL) and TA velocity (VT) arecalculated using the Brillouin shifts (Δν) by(i=L, T),(1)

where λ is the wavelength of the incident laser (532nm). The advantage of the 90oA-scatteringgeometry is that the determination of sound velocity
is independent of the refractive index of the sample[3].
VL and VT are shown in Fig. 3 as a function of
the composition at room temperature (RT). Since
the range of the studied composition in the previous
paper was limited up to 34 mol%, information for
the wide composition range was lacking. The
present study reveals that the composition
dependence of sound velocity over a wide
composition range. The values of VL and VT do notchange in a monotonic way with the increase of
K2O but a maximum around 30 mol%. This trend isstrongly correlated with the formation of the
4-coordinated boron atoms, studied by NMR [4].
The networks of the pure B2O3 glass are constructedby the planar 3-coordinated boron atoms. The
addition of the K2O causes the formation of
4-coordinated boron, resulting in the creation of the
3-dimential rigid structural units.
The elastic constants such as longitudinal
modulus (L), shear modulus (G), bulk modulus (K),Young’s modulus (E) and Poisson’s ratio (σ) aredetermined by sound velocity. Figure 4 shows thecomposition dependences of L, G, K, E andσ.
These elastic contents exceptσshow a maximum ataround 30 mol%, and then decrease with theincrease of K2O composition as similar as soundvelocity. These behaviors are discussed byoccurrence of non-bridging oxygen that destroys
the glass network or coordination number change ofboron. Poisson’s ratio is shown different behavior
from other elastic constants such as L, G, K, and E.

1600

LA

1400

Intensity (arb. units)

2

TA

1200

x=39.320

1000

LA

800

TA

600

x=36.703

400
200

LA

TA

x=34.920

0
4

6

8

10

12

14

16

18

20

Brillouin shift (GHz)

Fig. 2 The Brillouin scattering spectra.

4.8

VL

4.4

Sound velocity (km/s)

λ ⋅ ∆ν i

4.0
Kodama et al.
present

3.6
3.2
2.8

VT

2.4
2.0
0

5

10

15

20

25

30

35

40

Molar composition of K2O (mol%)Fig. 3 The composition dependence of soundvelocity.
60

L (G pa)
G (G pa)
K (G pa)
E (G pa)

50

L, G, K, E (GPa)Vi =Acknowledgment
The author (Y M) is thankful for the JSPS Research
Fellowship 19.574.

40

a

30
20
10

0 .3 2 05
0 .3 2 0

p re s e n t
K o d a m a e t a l.

0 .3 1 5b

0 .3 1 0
0 .3 0 5σ

References[1] M. Kodama et al.: Jpn. J. Appl. Phys. 34 (1995) 2570.
[2] Y. Ike et al.: Jpn. J. Appl. Phys. 45 (2006) 4474.
[3] H. H. Krbecek et al.: Polymer, 37 (1996) 3483.
[4] G. E. Jellison et al.: Phys. Chem Glass, 19 (1978) 52.

0 .3 0 0
0 .2 9 5
0 .2 9 0
0 .2 8 5
0 .2 8 0

0

5

10

15

20

25

30

35

M o la r c o n c e n tra tio n o f K 2 O (m o l% )40Fig. 4 The composition dependences of (a) L,
G, K, E and (b) σ.

2P1-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 199- 200
11-13 November, 2008

Elastic constants of C12A7 single crystals studied byresonance ultrasound spectroscopy
超音波共鳴法を用いた C12A7 単結晶の弾性定数計測
Masataka Yamamoto1†, Ryuichi Tarumi2 and Masahiko Hirao1, Masahiro Hirano3, Sung
Wng Kim4 and Hideo Hosono4 (1Grad. Sch. Eng. Sci., Osaka Univ., 2Grad. Sch. Eng.,
Osaka Univ., 3 FCRC, Tokyo Inst. Tech., 4Mat. Struct. Lab., Tokyo Inst. Tech.)山本昌孝 1‡，垂水竜一 2，平尾雅彦 1，平野正浩 3，金聖雄 4，細野秀雄 4 (1 阪大 基礎工; 2 阪大 工; 3
東工大 フロンティア; 4 東工大 応セラ研）

1. Introduction
C12A7:O2- (Ca24Al28O66: 12CaO･7Al2O3) and related
compounds are attracting materials for their amazing
crystalline structures and wide-varying physicalproperties. The C12A7:O2- is constructed from two
molecules, 2x(12CaO+7Al2O3), and its chemical formula
is given in the following form,

investigated by a precise measurement of macroscopic
physical properties. Needless to say, this analysis isalso valid for 2O2- in C12A7:O2-. In this study, weinvestigate a complete set of elastic constants Cij of
C12A7:O2- and C12A7:e- single crystals to discuss theoccupation sites of 2O2- and 4e-.

[Ca24Al28O64]4++2O2-.

2. Experimental procedure
Materials used in this study are rectangularparallelepiped shaped C12A7:O2- and C12A7:e- single
crystals prepared by Czochralski method. Table I
summarizes dimensions and mass densities of thespecimens.
Free vibration resonance frequencies, fi, of a
specimen depend on the dimension, mass-density andelastic constants Cij. We can inversely determine Cijfrom the resonance frequencies fi by Lagrangianminimization scheme solved with Rayleigh-Ritz method.
We employed electromagnetic acoustic resonance(EMAR)5) to measure the resonance frequencies. Here,
we briefly summarize the EMAR measurement
procedure. A single crystal specimen is inserted into asolenoid coil, both of which are set in a static magnetic
field (~0.2 T). The coil is driven by tone-burst currents(~1 MHz, ~30 μs), which induce the eddy current in thespecimen surface. The eddy current and the static
magnetic field interact to cause cyclic Lorentz force,
which excites ultrasound vibration in the specimen.
The reverse process occurs in the detection of ultrasoundvibration. Free vibration resonance spectra are thenobtained by a frequency sweep of the input current.
Resonance frequencies are determined by Lorentz
function fitting procedure around the resonance peaks.

Here, positively charged [Ca24Al28O64]4+ ions make aframework structure in its unit cell,1) which can beinterpreted as an aggregation of 12 empty cages. On
the other hand, two O2- ions occupy 2 of the 12 cages sothat the C12A7 have 2 occupied and 10 unoccupied
cages in its unit cell. Recently, Hosono et al. replaced
the encapsulated O2- ions by other active anions such as
O2- (superoxide radicals) and H- (hydride ions).2) Later,
they succeeded to replace the O2- by the supreme minus
ion, that is, electron e-. The chemical formula of
C12A7: e- is[Ca24Al28O64]4++4e-.
The C12A7:e- is called electride. This is the firstelectride, which is chemically stable at ambient
temperature.
Kim et al. investigated temperaturedependent electrical conductivity of the C12A7:eelectride and found superconducting transition below 0.2
K.3) However, most of fundamental properties of theelectride are still unclear yet.
One of the key questions is the occupation site ofelectron in the 12 cages. As well as C12A7:O2-, it isreasonable to suppose that 4e- electrons occupy 4 of 12
different cages. The framework structure (or 12 empty
cages) is known to have a cubic type
Td point group_symmetry (space group symmetry is I43m). According
to the Neumann’s principle,4) microscopic point groupsymmetry governs macroscopic physical properties.
Thus, the symmetry of macroscopic physical properties
will not change if 4 electrons do not have predominantoccupation site; namely 4 electrons occupy random
position in 12 cages. On the other hand, tetragonal
symmetry of macroscopic properties will change if andonly if 4 electrons have certain predominant occupationsites. Thus, the occupation site of 4e- electrons can be-------------------------------------------------------------y-masa@mbox.me.es.osaka-u.ac.jp

Table I. Dimension and mass-density of C12A7: O2- andC12A7: e- single crystals.
Dimension
Density
Specimen(mm)(kg/m3)
2C12A7: O
10.02
5.54
4.72
2680
C12A7: e3.23
4.94
3.09
2648.5

3. Results and discussion
3-1. C12A7: O2As mentioned above, the point group symmetry (orelastic symmetry) of the C12A7:O2- is unclear because
the occupation site of 2O2- ions has not been identified
yet.

Figure 1. Temperature dependence of elastic constants Cij(T) of C12A7: O2- single crystal determined by EMAR.
Einstein temperatures estimated from Varshni’s equation.6)

In this study, we assumed the orthorhombic typeelastic symmetry,
⎡C11
⎢
⎢
⎢
C ij = ⎢
⎢
⎢
⎢
⎢⎣

C12

C13

0

0

C 22

C 23

0

0

0

0

C 44

0
C 55

C 33
sym.

0 ⎤
0 ⎥⎥
0 ⎥
⎥
0 ⎥
⎥
⎥
C 66 ⎥⎦The number of independent Cij components is 9.
Figure 1 shows temperature dependence of elastic
constants Cij obtained from C12A7:O2-. As mentioned,
point group symmetry of the framework structure is Td.
In this case, Cij satisfies the following relations,

Arrows show

type elastic anisotropy.
Thus, the point groupsymmetry expected from the Cij measurement is D2d or
S4.
One of the plausible interpretations of the present
results is that the positions of 2O2- and 4e- in the 12
cages are not random. Namely, there exist predominantoccupation sites to minimize the internal energy of thesystems. Their accurate positions are still uncertain.
This is open for the future work.
Table II Elastic constants Cij (GPa) of C12A7:e- single crystal
obtained by EMAR at ambient temperature.
C11
C22
C33
C23
C31
166.48173.90171.04
69.24
57.67
C12
C44
C55
C66
65.09
53.93
59.14
51.54

C11= C22 =C33, C44= C55 =C66, C12= C23 =C31.
From the measurement, however, we find the relation of
C22 ≒ C33, C55 ≒ C66 and C31 ≒ C12 throughout thetemperature range.
This result indicates that the
C12A7:O2- has a tetragonal type elastic anisotropy. It istherefore reasonable to conclude that 2O2- ions havespecific occupation sites in 12 cages. Figure
2 shows a_group–subgroup relationship about the I43m. The lesssymmetric point groups that belong to tetragonal classare D2d and S4.

I43m (Td)
I42m (D2d)

I23 (T)R3m (C3v)

I4 (S4) Fmm2 (C2v) I222 (D2)C2 (C2)

Cm (CS) R3 (C3)_

Figure 2. Group–subgroup relationship about the I43m (Td)symmetry. There are two subgroups that have tetragonal
symmetry; D2d and S4.

3-2. C12A7:eTable II summarizes elastic constants of C12A7:emeasured by EMAR at ambient temperature. We
observe that C11 ≒C22 ≒C33, C55 ≒C66 and C31 ≒C12.
This result suggests that C12A7:e- also has a tetragonal

4. Conclusion
In this study, we investigated complete sets of elastic
constants of C12A7:O2- and C12A7:e- by EMAR. The
present results showed that both of the two crystals havea tetragonal type elastic symmetry. Their point groupsymmetry is D2d or S4, as can be expected from thegroup-subgroup diagram. These results suggest that
2O2- and 4e- have specific occupation sites in the 12
cages.
References
1 S. Watauchi et al.: J. Cryst. Growth, 237 (2002)
496-502.
2
H. Hosono: Sci. Tech. Adv. Mater., 5 (2004)
409-416.
3
M Miyakawa et al.: J. Am. Chem. Soc., 129 (2007)
7270 -7271.
4 Neumann’s principle; “Any symmetry exhibited by
the point group of the crystal (the macroscopic
symmetry: rotations, reflections, and inversion)must also be possessed by every physical propertyof crystal” (A. S. Nowick, Crystal Properties via
group theory, Cambridge university press, New
York, 1995).
5
M. Hirao and H. Ogi, EMATs for Science andIndustry, (Kluwer, Boston, 2003).
6 Y.P. Varshni: Physica, 34 (1967) 149.

2P1-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 201- 202
11-13 November, 2008

Ultrasonic Study of h-BN Machinable Ceramic (Ⅲ )ｈ － BN セ ラ ミ ッ ク の 超 音 波 に よ る 研 究 （ Ⅲ ）Nobuo Kashiwagura† , Motoki Satoh, Mitsuo Yamaga, Masayuki Akita
and Hiroaki Kamioka (Fac. of Eng., Gigu Univ.)
柏倉伸男†、佐藤元樹、山家光男、秋田正之、上岡宏彰（岐阜大学工学部）

1. Introduction
Hexagonal boron nitride (h-BN) has agraphite-likestructure,andexhibits
cleavage perpendicular to the c-axis.
Because of the cleavage nature, the sinteredh-BN becomes machinable, i.e. is machined
to small tolerances with conventional metal
working tools such as a lathe or a drillingmachine. The material is also a good
insulator, chemically stable, impervious togas penetration and able to withstand hightemperatures (to approximately 1000℃).
The excellent properties enable wide
application in the fabrication of vacuum
components and high pressure and/or hightemperature parts in addition to providing
various other uses.
Despite numerous studies of the elasticityof the machinable ceramics which can beused as high temperature components, few
previous studies have reported the elastic
properties in the high- temperature region
above 500 ℃ .
The velocities ofcompressional waves and shear waves andtheir attenuation in the material wereprecisely measured using ultrasonic pulse
transmission in the temperature range
between 30 ℃ and 1000 ℃ , and elastic
moduli were calculated from the wave
velocities. In this study, we focus on thetemperaturedependenceofelastic
properties of h-BN machinable ceramic in
the high-temperature range. It is interesting
to compare elastic properties of h-BN withthose of Macor 1).
2. ExperimentalAcylindricalsampleofh-BN
approximately 38.0 mm in diameter and20.0 mm long was prepared with flat andparallel faces by conventional machining.
Its measured density was 2.26 g/cm 3 .
A schematic diagram of the measurement
system which was specially designed forthe precise measurement of ultrasonicvelocityathightemperatures(toapproximately 1000℃) is shown in Fig.1.
For the measurements, an ultrasonic wave
of 0.5 MHz and the pulse transmission
method using a dual acoustic path were
employed 1-6). In this system, one pathconsists of a vertical mercury delay line,
which precisely measures the distance
between transducers by use of a
micrometer, and is necessary for the
precise measurement of ultrasonic velocity,and the other consists of a high-temperature
furnace with the sample and stainless steel
buffers inside. The temperature of thesample was controlled in the range from 30℃ to 1000 ℃ by a microcomputer. The
buffers reduce heat to prevent thedestruction of transducers (PZT, resonancefrequency : 0.5 MHz) in combination withwater jackets. The housing of transducers,
buffers and the sample were held together
under appropriate pressure (approximately
60 Kgf/cm 2 ) along the sample's cylindricalaxis.
Thus no acoustic binder was
employed at any interface between theFig.1. Schematic diagram of the apparatus
formeasuringultrasonicvelocity
andattenuation even at high temperature region.

transducers, the buffers and the sample forultrasonic measurements.
Tree same samples, DENKA type HC,
were prepared. Ultrasonic measurements
were carried out tree times for each sample.
The results of ultrasonic velocities at a
certain temperature are almost the same
within errors, and the averaged value isshown.
3. Results
The
temperaturedependenceofcompressional wave velocity and shear
wave velocity was measured during heating
and cooling in the temperature range from
30℃ to 1000℃, as is shown in Fig. 2. As
temperature increases, roughly speaking,compressional wave velocity stays almost
constant from room temperature (30℃)to
500℃, increases from 500℃ to 850℃, andthen stays almost constant again above 850℃.
Whereas the shear wave velocity
slightly decreases or stays almost constantfrom room temperature to 800℃, and thenincreases above 800℃.
Comparing with those of Macor 1 ), theratio of compressional wave velocitychange is very large around 30%, in case ofMacor, less than 2%).

700 0

500 0
Heating
○

650 0

450 0

●
Cooling

600 0

Heating

400 0Cooling

350 0

△
▲

550 0

500 0

300 0

450 0

250 0

400 0
0

200

400
Tem perature

600

800

200 0
1000

[℃]

Fig.2.
Temperaturedependenceofcompressional wave velocity (○:Heating , ●:Cooling) and shear wave velocity (△ :Heating ,▲:Cooling).

Ultrasonic measurement enables us toobtainelastic
moduliwithoutthedestruction of the sample that is
unavoidable in a standard tensile test.
Using an appropriate apparatus, wave
velocities can be measured over wide rangeof temperatures. It is significant toinvestigate elastic properties over thehigh-temperature region above 500℃ for amachinable ceramic, which is used for parts
experiencing temperatures up to 1000℃.
Using the values of the compressional
wave velocity and the shear wave velocity
as shown in Figs. 2, elastic moduli werecomputed using equations 2 ). Elastic moduli
depend on the density of a material, whichis affected by thermal expansion. In a hightemperature region, thermal expansion is nolonger negligible. Thus, elastic moduli arecorrected for thermal expansion.
The temperature dependence of the bulk
modulus, the modulus of rigidity andYoung's modulus will be shown in thesession. Knowledge of the temperaturedependence of elastic moduli of machinableceramics is useful for predicting the
behavior of a material in extensive
applications, even at high temperatures.
The ultrasonic wave method was applied
to investigate a machinable ceramic, h-BN,
across the temperature range from 30℃ to
1000℃. Ultrasonic measurement proved to
be sensitive and useful to investigate
elastic properties in a machinable ceramic,
even at high temperatures.
1)N.Kashiwagura,M.Akita and H.Kamioka:
Jpn. J. Appl. Phys. 44(2005)4339.
2)N.Kashiwagura,Y.Ohsawa,S.Iwata,J.Jin and
H.Kamioka:Jpn.J.Appl.Phys.9(2000)2928.
3) N.Kashiwagura, S.Sakai and H.Kamioka:
Jpn. J. Appl.Phys. 40(2001)3516.
4) N.Kashiwagura, S.Sakai and H.Kamioka:
Jpn. J. Appl. Phys. 41(2002)3176.
5)
N.Kashiwagura,
T.Muramatsu
andH.Kamioka: Jpn.J.Appl.Phys. 42(2003)2931.
6) N.Kashiwagura, O.Yoshida, M.Kobayashi,
K.Nakata, S.Mizuno and H.Kamioka: Jpn. J.
Appl. Phys. 43(2004)2905.

2P1-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 203- 204
11-13 November, 2008

Effect of polling process on property of hydrothermally synthesized PZT
polycrystalline film
分極処理が水熱合成 PZT 多結晶膜の特性におよぼす影響
Shinya Irisawa1†, Akito Endo2, Minoru Kurosawa3, Norimichi Kawashima1 and Shinichi Takeuchi1 (1Toin Univ. of Yokohama ,2
AIST, 3 Tokyo Institute of Technology.)
入澤信哉 1‡，遠藤聡人 2，黒澤実 3 ，川島徳道 1，竹内真一 1 (1 桐蔭横浜大院; 2 産総研, 3 東工大院)

1. Introduction
We are developing 10 MHz array typeultrasound probes with 8 elements hydrothermallysynthesized PZT polycrystalline film transducers
with wide of 35 μm, length of 4 mm.
Hydrothermally synthesized PZT polycrystalline
film is suitable for deposition on the complex
shaped or tiny sized Ti substrate and it shows
piezoelectricity without polling process. However,there is a problem with low sensitivity. Therefore,
we tried to improve its sensitivity by polling
process in spite of above features. Effect of polling
process on property of hydrothermally synthesized
PZT polycrystalline film is reported in this paper.
2. Fabrication of bimorph type vibrator withhydrothermally synthesized PZT polycrystalline
film
Bimorph type vibrators were fabricated bydeposition of hydrothermally synthesized PZT
polycrystalline film on the Ti substrate withthickness of 50 μm. Our hydrothermal method
includes nucleation process (NC) and crystal
growth process (CG). Nuclei of PZT polycrystals
are deposited on the Ti substrate in the material
solution under conditions of temperature 160 ℃
and synthesizing time 24 hours in 1 cycle of NC
process. The PZT crystals grow up under thecondition of temperature 140 ℃ and synthesizingtime 24 hours in 1 cycle of CG process. PZT
polycrystals are synthesized and deposited by 1
cycle of NC and 4 cycles of CG in this study. The
material solution was stirred by the Teflon stirring
blade with stirring speed of 245 rpm. Ti substrates
were held on the stirring blade directly.
Consequently, we obtained PZT polycrystalline filmwith thickness of about 10 μm. The SEM image of
PZT polycrystals deposited on the Ti substrate areillustrated in Fig.1. Au electrodes were deposited on
both sides of the bimorph type vibrators withhydrothermally deposited PZT polycrystalline films
as shown in Fig. 1.
-----------------------------------------------------------t17b010@edu.toin.ac.jp

Fig.1 The SEM image of hydrothermallysynthesized PZT polycrystalline film on Ti substrateof bimorph type vibrator
3. Polling process
We tried to improve the sensitivity ofbimorph type vibrators by polling process. The
polling process was performed by applying DC 10
and 20 V between both Au electrodes and Ti
substrate as shown in Fig. 2 for three hours in 80℃
silicon oil in the oil bath. 2 ways of polling process
were tried. DC voltage were applied between Au
electrodes as anode electrodes and Ti substrate as
cathode electrode as shown in Fig. 2 (a). The otherway is shown in Fig. 2 (b).

(a)

Ti film

Au electrodePZT film(b)
Fig.2 Polling processes for bimorph typevibrators with hydrothermally synthesized PZT
polycrystalline films
4. Experimentals
4-1. Measurement method of vibration velocity
The fabricated bimorph type vibrators
were driven electrically as shown in Figs.3 and 4.
The sinusoidal wave with amplitude of 5 V0-P wasprocess on vibration velocity are shown in Fig.5.
Dielectric constant decreased by the polling process.
The results are illustrated in Fig.6.
1

Vibration speed [m/s]applied to the vibrator with a function generator.
The vibration velocity was measured with Laser
Doppler Velositometer (LDV) as shown in Fig. 4.
The distance between free and fixed ends in thebimorph type vibrator was 15mm. The
measurement position of vibration velocity is 2mmfrom the free end.

0.8 Ti ・・・ AnodeAu ・・・ Cathode0.6

Ti ・・・ CathodeAu ・・・ Anode0.4

Not polling process

0.2
0Relative permittivity [F/m]Fig.3 Relationship between directions of crystal
growth of deposited PZT and applied electric field

300
400
200
500
Frequency [Hz]Fig.5 Effects of polling process on vibration
velocity of bimorph type vibrator withhydrothermally synthesized PZT polycrystalline
film
3000
Not polarization process

Fig.4 Vibration velocity measurement system ofbimorph type vibrator with hydrothermallysynthesized PZT polycrystalline film
4-2.Measurement method of dielectric constantCapacity CT between the Au electrodes
deposited on both sides of bimorph type vibrator
withhydrothermallysynthesized
PZT
polycrystalline film was measured. The Capacity CT
is expressed as eq. (4-1). Dielectric constant ε r isexpressed as eq. (4-2). C is of capacity ofhydrothermally deposited PZT polycrystalline filmon one side of Ti substrate of vibrators, S is crosssection of Au electrode, D is thickness of PZT film,
ε 0 is dielectric constant in vacuum.

C
2
2C D
εr = Ｔ ⋅
ε0 S
CＴ =

(4-1)
(4-2)

5. Results
The vibration velocity increased 50% bypolling process with applied voltage of DC 20 V
between Ti substrate as a cathode electrode and Au
electrode as anode electrode. The effects of polling

0

2500
2000

100

Ti ・・・ AnodeAu ・・・ Cathode

1500
1000

Ti ・・・ CathodeAu
・・・ Anode
0
0
200
400
600
800
1000
Frequency [KHz]
Fig.6 Effects of polling process on dielectric
constant of bimorph type vibrator withhydrothermally synthesized PZT polycrystalline
film
500

6. Conclusions
It was found that the vibration velocity
increased but dielectric constant decreased bypolling process. We will consider the effects ofpolling process by various voltages on the vibration
velocity, sensitivity and various material properties
in the future.
References
1. AEndo, M Ishikawa, N Kashima, M Kurosawa, S
Takeuchi, 2006 IEEE International Ultrasonics
Symposium. p.611. 2006.
2. M Ishikawa, M K Kurosawa, A Endo, and S
Takeuchi: Jpn J Appl Phys. 44 (2005) 4342.
3. A Endo, N Kawashima, S Takeuchi, M Ishikawa,and M K Kurosawa. Jpn J Appl Phys. 46 (2007)
4779.
4. T Hasegawa, H Kitsunai, N Kawashima, S
Takeuchi, M Ishikawa, and M K Kurosawa. Jpn J
Appl Phys. 46 (2007) 4801.

2P1-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 205- 206
11-13 November, 2008

Shear wave velocity of vanishing materials
Q. Hung Truong1‡, Yong-Hun Eom1, Changho Lee2 Jong-Sub Lee1
(1 Korea University, 2 Georgia Institute of Technology)

1. Introduction
Soil containing soluble grains, such as salt,
limestone, gypsum, dolomite, and halite [1] aresusceptible to the change of the properties due tothe dissolution of theses particles. Particle
dissolution results in changes of the microstructure of mixtures that can affect the strength anddeformation behavior. The dissolution yields thegreater hydraulic permeability that plays a crucilarole in the safety of structures. For examples, theone of the factors of the St. Francis Dam failure is
the dissolution of the partilces. However, there is alack of information about the changes of shear
wave velocity of the vanishing during dissolution
under no lateral strain condition. This research
includes experiment program, equipment system,
experimental results and discussions of shear wave
velocity during dissolution.

The effects of local void on the micro to macro
mechanical behaviors of vanishing mixtures are
explored by implementing shear wave in aconventional oedometer cell equipped with benderelements, as shown in Fig. 2 [4]. The vertical load
is applied into the cell. When the vertical load isreached to a planned stress (80kPa and 320kPa), theelectrolyte, NaCl 0.01M, is slowly and carefully
poured into the cylindrical container to dissolve thevanishing minerals. The electrolyte level in thecontainer is kept lower than that in the specimen toprevent the flow of water from top to bottom at the
beginning of the vanishing. Thus, the electrolyte
gradually flows from the bottom to the top of
specimen. The electrolyte in the container is kept toensure the dissolution of all soluble mineral inside
the mixtures. The fabric change due to thenon-soluble particle relocation may occur during
vanishing.

2. Experimental study
The vanishing mixtures are prepared using
sieved table salt and Jumunjin 40/50 sand, as shownin Fig. 1. The table salt used sieved using 50/70
sieves is uniform, fine, and cubic grain salt. The
mean grain size of the sand particle is about 1.5
times larger than that of salt particle. The smaller
salt particles can be placed into the pores between
larger sand particles. Thus, the minimum volume
change is expected due the vanishing. The use of
artificial specimen may provide a valuable insightview in macroscale mechanical response of soil [3].
Vanishing mixtures are prepared with 10% saltcontents in volume. The vanishing mixtures arefunneled into the oedometer cell in five layers. Eachlayer is compacted by the same tamping numbers to
produce homogeneous specimens and simulate theconstruction of the earth dam.
(a)

500um

Fig. 1. Photograph Image: (a) Table salt particle; (b)Sand particle.

-----------------------------------------------------------Email: jongsub@korea.ac.kr

Filter-Amplifier

Signal Generator
SIGNAL

OscilloscopeComputerFig. 2. Experimental setup. BE denotes a bender element.

3. Experimental results and discussions

(b)

500um

BE
Sand-salt
BE

During dissolution of the vanishing materials
after the specimen is fully saturated, the verticalstrain and shear waves are continuously monitored(see Fig. 3). The process monitoring of verticalstrain and shear wave velocity show that thevanishing behavior can be categorized into three
regions. In the first region, which ranges 0 ~ 0.3
minutes after saturation started, the vertical strain
increases and the shear wave velocity tremendously
decreases. When the specimen changes from the dry
condition to saturation condition, the change of thewhere Θ, ζ and Ψ are the factors represent material
parameters to be experimentally determined [5].
Therefore, the decrease (up to 25%) of shear wave
velocity with axial strain increase can be explained
due to the change of mass density, the void ratio,
mechanical fabric changes and the stress as well as
material anisotropy changes.
120

Beforedissolution

100

80kPa
320kPaGs [MPa]

velocity is huge because the shear wave velocity
can detect local change within the specimen. Thechange of the vertical strain, however, is minor
because the vertical strain reflects the global changeof the specimen. The change of the vertical strain
and shear wave velocity results from the electrolyte
flow and the vanishing of salt particles. In thesecond region (0.3~10 minutes), the increment of
the vertical strain decreases, and the velocity
increases after it decreases. The change of theincrement of the shear wave velocity may be relatedwith reorientation of the sand particle after
dissolution of the salt particle. In third region (after
10 minutes), only minor vertical strain occurs. Thus,
the shear wave velocity becomes stable.

80

60

270

(a)

40

Beforedissolution

250

80kPa

Vs [m/s]

20
0.001

320kPa

230

210

1

10

100

1000

Fig. 4. Evolution of small strain shear modulus during
dissolution.

170

4. Conclusions

150
0.001

0.001

0.01

0.01

0.1

1

10

100

1000

0.1

Time [min]
1

10

100

1000

The effect of the dissolution of the particles
was studied using the artificial specimens preparedby mixing sand and granular salt, then dissolving
the salt grains. The small strain shear wave velocitychanged up to 25% or the small strain shear
modulus changed up to 40% during particle
dissolution. The small strain shear wave parameters
are effective in detecting and quantifying the fabricchanges associated with particle-dissolution
processes.

0.000

0.005

Beforedissolution
80kPa

0.010
Vertical strain

0.1

Time [min]

190

(b)

0.01

320kPa
0.015

0.020

0.025

0.030

0.035

Fig. 3. Process monitoring during dissolution ofvanishing materials at the vertical effective stresses of 80
kPa and 320 kPa: (a) Vertical strain versus time; (b)Shear wave velocity versus time.

The small strain shear modulus Gmax is obtainedusing the shear wave velocities VS and thecorresponding mass density ρ(1)Gmax = ρ⋅VS2
The small strain shear modulus during dissolution isplotted in Fig. 4, which shows the decrease of thesmall strain shear modulus during vanishing. Notethe shear wave velocity and the mass density
decrease during dissolution.
Empirical relation of shear wave with propagation
direction of x and particle motion of y depends on
the stresses on the x and y direction σx and σy isς⎛ σ x +σ y ⎞ ⎛ σ x -σ y ⎞VS =Θ ⎜
⎟ ⎜⎟⎝ 2kPa ⎠ ⎝ 2kPa ⎠Ψ

(2)Acknowledgment
This work was supported by BK-21 Global
Leaders in Construction Engineering, Korea
University, Korea.
References
1. F.G. Bell: Engineering Geology (Elsevier, 2004).
2. D. Craft, C. Cain, and C. Sullivan: Technical
Memorandum 86-6829010, U.S. Department of
the Interior - Bureau of Reclamation (2006).
3. M. A. Fam, G. Cascante, , and M. B. Dusseault: J.
Geotech. Geo.. Eng., 128 (2002).
4. J.S Lee. and J.C. Santamarina: J. Geotech. Geo.
Eng. 131 (2005).
5. J.C. Santamarina, K.A. Klein and M.A. Fam:
Soils and Waves (JohnWiley and Sons, 2001).

2P1-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 207- 208
11-13 November, 2008

Modulus change of rigid-soft mixtures during cementation
Changho Lee1‡, Q. Hung Truong2, Hyung-Koo Yoon 2, Jong-Sub Lee2
(1 Georgia Institute of Technology, 2 Korea University)

1.

Introduction

Applications of the shredded tires increase tosolve not only environmental but also economical
problmes. Addtion of soft particle into the soil
decreases in the specific gravity, mass density,
permeability of water, strength, and stiffness, andincreases in compressibility and damping [2], [3].
Cementation remarkbaly changes the stiffness andstrength of the soil so that it is often adopted to aground improvement. Modulus change is exploredto monitor vertical settlement and elastic wave
velocities during cementation. This study includes
experimental setup with specimen preparation,
experimental results and discussions of modulus
change during cementation.
2.

Experimental study

The rigid-soft particle mixtures are preparedusing pre-sieved shredded tire and Jumunjin 20/30
sand, as shown in Fig. 1. The mean particle size oftwo particles is 0.725mm. The rubber is angular andirregularly shaped and the sand is uniform, coarse,
and angular. The maximum and minimum void
ratios are emin=0.60 and emax= 0.87, repsectively.
Specimens are prepared with three different
volumetric sand fraction (sf=Vsand/Vtotal=0.2, 0.6,
and 0.8). Portland cement is used as the
cementation agent. Dried sand and rubber particles
are mixed with Portland cement of 20g anddeionized water for 5 minutes in the container. Well
mixed specimen is carefully scooped into four
layers. Each layer is lightly compacted by the same
tamping numbers to apply same amount of compact
energy. When the mixture is filled in the oedometer
cell, the top cap is placed on the mixture. The initialheight and weight of the specimen is measured todetermine the initial condition of the specimen.
(b)

(a)

760μm

760μm

Fig. 1 Photograph Image: (a) Shredded rubber; (b)Jumunjin 20/30 sand.

-----------------------------------------------------------Email: jongsub@korea.ac.kr

Bender elements 11.0×4.0×0.6 (length × width ×
thickness in mm) and piezo-disk element
14×20×0.45 (ceramic dia.× sensor dia. ×thickness
in mm)) are used as transducers to measure theshear and primary waves. All transducers arewaterproofed and electrically shielded. The
transducers are installed into the top cap and bottom
plate of the odeometer cell to gather elastic waves
along vertical direction in the transmission mode as,shown in Fig. 2 [1].
The vertical sitting stress (σsit =21kPa) is appliedand maintained for 72 hours during hardening of
cementation agent. Axial strain and P- and S- waves
are measured to monitor the void ratio change andthe evolution of the modulus of the specimens withtime under no-lateral deformation.
ΔhLoading
Oscilloscope
input signal

BE

PZT
Specimen

SIGNAL

Signal generator

PZT

BE

Filter-Amplifier
output signal monitoring

Fig. 2 Experimental setup. BE and PZT denote a benderelement and piezo-disk element, respectively

3.

Experimental results and discussions

The rubber is a typical creep material. Fig. 3
shows the vertical settlement of tested specimens
with time. A large deformation is observed in all
specimens immediately after applying the verticalload. The vertical settlement increases with adecrease in the sand fraction for an applying
vertical stress because the rubber particles easily
distort. The vertical settlement approaches
gradually asymptotic value about 1~24 hours after
loading. Note that as the sand fraction decreases,
the settlement increases.
Evolutions of measured elastic wave signals areshown in the Fig. 4 for sf=0.6 at the fixed verticalstress (21kPa) with time. The travel times of P- andS-wave are almost constant for about 30 minutethe effective stress on the particle-to-particle
contact. However, cementation increases particle
contact area so that it remarkably affects thestrength and modulus of the specimen.

after applying vertical load. The traveling times ofP- and S- waves decease and the resonant frequencyof P- and S- waves increases significantly due to thecuring process.

(a)

0

350

sf=0.2
sf=0.6
sf=0.8Settlement[10-3 mm]
Settlement

Constraint Modulus, M [MPa].

300
200

sf=0.8sf=0.6400

600

sf=0.2

800

250
200
150
100

Beforecementation

50
1000
0.001

0.01

0.1

1
10
Curing Time [hr]100

00.00011000(b)Fig. 3 Vertical settlement with time.

M = ρ⋅VP2
Gmax = ρ⋅Vs2

Shear Modulus, G [MPa].

(1)
(2)

Curing time

4 min

2

1 min

2

2 min

8 min

60 min

6

2 hr
3 hr

8

8 hr
21 hr

10

24 hr
33 hr

12
10

45 hr
55 hr

30 min60 min

8

2 hr
3 hr

10

72 hr
0.2
0.2

0.4
0.4

0.6
0.6

Time [ms]time [ms]

0.8
0.8

1.0

1000

0.1
1
Curing Time [hr]

10

100

1000

200
150
100

Beforecementation

0.001

0.01

Conclusions

Modulus change in rigid-soft particle
mixtures is studied by monitoring verticalsettlement and elastic wave velocities. The verticaldeformation approaches gradually asymptotic value
in about 1~24 hours after loading. The effect of
cementation increases the constraint modulus andshear modulus under a fixed vertical effective stressbecause particle level contact area increases withthe cementation. The higher the sand fraction, thehigher the moduli. This study shows that theultrasonic wave velocity can be effective tools formonitoring of modulus change during cementation.

8 hr
21 hr

12

24 hr
33 hr

10
14

45 hr
50 hr

12

55 hr

69 hr

14

00

15 min

6

50 hr

14
12

16

8 min
Measured shear wave signals

Measured primary wave signals

30 min4 min

415 min4

4.

30 sec2 min

100Fig. 5 Modulus change during cementation: (a)constraint modulus; (b) shear modulus.

0 min

0

10

250

0
0.0001Curing time

(b)

0 min

0

0.1
1
Curing Time [hr]50

The evolutions of constraint and small strain shear
modulus are plotted in Fig. 5 during cementation
hardening. The moduli is almost constant until 0.3
hour (for sf=0.8) ~ 3 hour (for sf=0.2). The
constraint modulus and shear modulus of thespecimens increase dramatically due to the curingof cementation agent. The modulus change of thehigher sf specimens (sf=0.8) are higher than that of
the lower sf specimens (sf=0.2).
(a)

0.01

sf=0.2
sf=0.6
sf=0.8300

The constraint modulus M and the small strain
shear modulus Gmax can be obtained from thecalculated the primary wave velocity VP and theshear wave velocities VS, and the corresponding
mass density ρ

0.001

350

69 hr

14

72 hr
16

00

Acknowledgment
This work was supported by BK-21 Global
Leaders in Construction Engineering, Korea
University, Korea.

0.2
0.2

0.4
0.4

0.6
0.6

0.8
0.8

Time
[ms]
time [ms]Fig. 4 Evolution of measured signals for sf=0.6 at fixedvertical stress σ'v=21kPa: (a) Primary wave; (b) Shearwave.

The stiffness of granular material is a function of

1.0

References
1. C. Lee, J.S. Lee, W., Lee, and T.H. Cho: Geotech.
Test. J., 31(2), (2008).
2. J. G. Zonberg, A. Canral, and C. Viratjandr: : Can.
Geotech. J., 41(2) (2004).
3. Z. Y. Feng K. G. Sutter: Geotech. Test. J., 23(3),(2000).

2P2a-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 209- 210
11-13 November, 2008

Accurate distance measurement by pulse compression using
linear-period-modulated signals and calibration of Doppler shift
線形周期変調信号を用いたパルス圧縮とドップラーシフト補正による高精度距離計測
Shinnosuke Hirata1†, Minoru Kuribayashi Kurosawa１ and Takashi Katagiri2(1Dept. of Information processing, Tokyo Tech; 2Sutekina Inc.)
平田慎之介 1†, 黒澤実 1, 片桐崇 2 (1 東工大 総理工; 2 すてきな (有))1.

Introduction

The pulse-echo method is the tyipical method of
ultrasonic distance measurement. The method is basedon determination of the time of flight (TOF) of
ultrasonic waves. For improvement of the distanceresolution and reduction of white noise of echoes,
pulse compression has been employed in the method.
A linear-frequency-modulated (LFM) ultrasonic pulse
is transmitted in typical pulse compression. A
received signal, which includes reflected echoes, iscorrelated with a reference, which is the transmitted
ultrasonic pulse. The signal processing for pulse
compression consists of huge iterations ofmultiplications and accumulations. Real-time distancemeasurement by pulse compression is difficult
because of requirement of high-cost digital signal
processing. For reducing the calculation cost of pulse
compression, a sensor signal processing method using
a delta-sigma modulated single-bit digital signal has
been proposed[1]. Cross-correlation by single-bit
signal processing of the proposed method can reducethe calculation cost.
However, if an object is moving, due to the
Doppler effect introduced by the motion of the object,echoes are Doppler-shifted. The distance of themoving object cannot be accurately measured because
the Doppler-shifted LFM signals cannot be correlatedwith the transmitted LFM signal. In this paper, a
low-calculation-cost method for accurate distancemeasurement of moving objects is proposed. In the
proposed method, the TOF and the Doppler velocity
of moving objects are measured by pulse compression
using linear-period-modulated (LPM) ultrasonicpulses. The distance can be accurately measured bycalibration of the TOF with the Doppler velocity.

Linear-period modulation
Doppler shift is linear compression or
expansion of the signal period in proportion to the
Doppler velocity of moving objects. Therefore, theDoppler-shifted LFM signals cannot be correlatedwith the transmitted LFM signal.
Pulse compression using LPM signals has been
proposed for ultrasonic distance measurement ofmoving objects [2]. An LPM signal is written as
u t

ln t

a sin 2π

p

φ ,

(1)

where a is the signal amplitude, l is the signal
length, p is the initial signal period, p is the chirp
rate of the signal period, and φ is the constant ofphase. The period of the LPM signal linearly chirps
with time. Therefore, the Doppler-shifted LPM signals
can be correlated with the transmitted LPM signal.
The LPM signal is thus suitable for cross-correlationof Doppler-shifted signals.

3.

Doppler velocity estimation

The TOF of the Doppler-shifted LPM signal isdetermined from the peak of cross-correlation
function of the Doppler-shifted LPM signal and thetransmitted LPM signal. However, the TOF is also
Doppler-shifted by three factors, 1: increase or
decrease of traveling time of ultrasonic waves, 2:change of correlative period band, and 3: phase shiftof the peak of the cross-correlation function.
Therefore, calibration of the Doppler-shifted TOF
with the Doppler velocity is necessary for accurate
distance measurement of moving objects.
In the pulsed Doppler method, the Doppler
velocity is estimated from the Doppler-shiftedfrequency of the echo, which is given by Fouriertransform. The disadvantages of Fourier transform are
low velocity resolution and high cost digital signal
processing. Similar to the frequency, the signal period
and signal length of the echo are Doppler-shifted.
Therefore, the Doppler velocity can be estimated fromthe Doppler-shifted length. The Doppler-shifted
length is expressed as,

2.

† hirata.s.ab@m.titech.ac.jp

l

v⁄v

v

· l,

(2)

where l is the Doppler-shifted signal length, and lis the length of the LPM signal. v is the Doppler
velocity, and v is the velocity of ultrasonic wave inair. Fig. 1 shows a proposed method of accurate
distance measurement by transmitting two LPM
signals. When two LPM signals are continuously

Figure 3: The distance measured
from the Doppler-shifted TOF

Figure 1: Design of the proposed methodof accurate distance measurement

Figure 4: The distance calibrated
with the Doppler velocity

Figure 2: The cross-correlation function of
the transmitted two LPM signals and the LPM signaltransmitted, the cross-correlation function of thetransmitted two LPM signals and an LPM signal has
two peaks, as illustrated in Fig. 2. The interval of thefirst peak and second peak of the cross-correlation
function shows is the Doppler-shifted signal length l .

4.

Calibration with Doppler velocity

The proposed method of accurate distancemeasurement by transmitting two LPM signals wasevaluated by a computer simulation using MATLAB.
In the simulation, the period of an LPM signal chirps
from 16.67 μs to 50 μs, and the duration of the signal
was 5 ms. The duration of transmitted two LPM
signals was 10 ms. The distance to the object was 1 m.
The velocity of ultrasonic wave in air was 344 m/s atapproximately 20 ℃. The sampling frequency was
12.5 MHz. The cross-correlation function was
obtained from cross-correlation by single-bit signal
processing.
The distance, which measured from theDoppler-shifted TOF, is illustrated in Fig. 3. The
distance, which calibrated with the Doppler velocityof Fig. 3, is illustrated in Fig. 4. The distance ofmoving objects can be accurately measured bycalibration of three factors of Doppler shift. The
proposed method of accurate distance measurement
does not require additional calculation cost beyond thepulse compression.

5.

Conclusion
A low-calculation-cost method for ultrasonicdistance measurement of moving objects is proposed.
Pulse compression by transmitting two LPM signals
can measure the Doppler-shifted TOF and estimate theDoppler velocity of moving objects with highresolution. By calibrating the Doppler-shifted TOF
with the Doppler velocity, the distance of the moving
object can be accurately measured.
Acknowledgments
This work was supported by a Grant-in-Aid for
Research Fellowships of the Japan Society for the
Promotion of Science for Young Scientists.
References
1. S. Hirata, M. K. Kurosawa, and T. Katagiri:
IEICE Trans. Fundamentals E91-A, No.4
(2008) p. 1031 - 1037.
2. J. J. Kroszczynski: Proc. of the IEEE, Vol. 57, No.7
(1969) p. 1260 - 1266.

2P2a-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 211- 212
11-13 November, 2008

A Study on Liquid-Level Sensing by Using
Trapped-Energy-Mode Thickness Vibrations
エネルギー閉じ込めモード厚み振動を利用した
微小液面レベル変化の検知
Ken Yamada1,2†, Hisato Honda1, Shuhei Horiuchi2, and Tetsuya Kinai1 (1Faculty ofEng., Tohoku gakuin Univ.; 2 Graduate School of Eng., Tohoku Gakuin Univ.)
山田顕1,2‡，本田斐聡1，堀内修平2, 木内哲也1（1東北学院大・工; 2東北学院大・院・工）1. Introduction
Detection and/or sensing of the liquid level byusing ultrasonic techniques has widely been used sofar. Most of the techniques employ the pulse-echo
method to detect the variation in the liquid level. In
recent years, measurement of liquid level inmillimeter scale or less has become an importantsuject in, for example, biological and chemical
fields. However, the pulse-echo method isinadequate for the measurement of variation in sucha small scale. As an example of an alternatinve
method, liquid level sensing using a self-excitedsmall PZT-cantilever has been proposed1). In thispaper, a new method is presented that employs apiezoelectric thickness vibrator operating in atrapped-energy mode for detecting a small-scalevariation in the liquid level. The energy-trapping
phenomenon in thickness vibration modes wasfound by Shockley et al.2) and has been applied
successfully in piezoelectric resonators and/or
filters over several tenth of years. Application ofthis phenomenon to the liquid level sensing should
be a new and unique attempt that might have notbeen tried yet.
2. Principle of operationLet
usconsiderathickness-mode
piezoelectric vibrator having a partially-electroded
region at its center such as that shown in Fig.1(a).
Because of the piezoelectric effect, the cut-off
frequency in the electroded region, ω0, is slightly
lower than that, ω 0’, in the surrounding(unelectroded) region. In this configuration, theresonant vibration occurs between ω0 and ω0’.
The wavenumber in the electroded region,γ, isreal, whereas that in the surrounding region,
γ’,is imaginary. Therefore, the vibration energy
is confined in the central region and decays
exponentially in the surrounding region. Thus theenergy-trapping works, and an evanescent field iscreated in the unelectroded region, such as shown in
Fig.1(b).
-----------------------------------------------------------† k-yamada@tjcc.tohoku-gakuin.ac.jp

Fig. 1(a)Trapped-energy-mode vibrator.

γ ：Realγ ’ ：Imag.

γ ’ ：Imag.

ω0 '

ω0

ω0 '

Fig. 1(b) Displacement distribution for trapped-energy
mode.

If the unelectroded region is dipped in aliquid, a small amount of leakage of the vibrationenergy will occur. The amount of the leakage willvary depending on how deep the surrounding region
is dipped in the liquid. Therefore, the electriccharacteristics of the vibrator such as the Q-factor
and the electric conductance G at the resonance willvary in accordance with the immersion depth. This
will enable us to the sensitive detection of variationin the liquid level in a small scale.
3. Experimental setup

A thickness-poled PZT plate (NEPEC-6) of
30 mm in diameter and 1 mm in thickness having a
4 mm diameter electrode was employed as thevibrator material. Figure 2 shows the frequency
characteristics of the electric admittance |Y| and theelectric conductance G. The resonance frequency
was 2.09 MHz and the Q-factor was about 400. The
plate was supported vertically by clamping its
fringe. Because the vibration energy is confined tothe electroded region, the clamping does not cause
deterioration of the Q-factor. Then, the plate was

(a)4. Results

Admittance |Y| (mS)
Frequency (MHz)(b)

Figure 4 shows the variations of G obtained
for the four different kinds of liquids. The verticalaxis is normalized to the maximum values Gmax foreach of the liquids. The origin of the horizontal axis
corresponds to the boundary between the electroded
and the unelectroded regions. The positive value ofh means that the liquid surface is at theunelectroded (evanescent wave) region, whereas thenegative value of h means that the liquid surface
goes up beyond the electrode edge. In any cases
the G value decreases gradually according to theincrement of the liquid level. The variations of G
are almost linear in the range ±5 mm from theelectrode edge. It might be said that the variationis steeper for the liquid having higher viscosity.

Conductance G (mS)Electroded region

Unelectroded region

G / Gmax

Water
Glycerin
Caster oil
HoneyFrequency (MHz)Fig. 2Depth h (mm)Frequency response of admittance (a) andConductance (b) for the vibrator.

Fig. 4 Variations in normalized G vs. depth h for 4
different liquids.

Trapped-energy-mode
vibrator

5. ConclusionshTest liquid

Fig. 3

Experimental setup for measurements.

dipped in a liquid to be tested such as shown in
Fig.3. The test liquids employed were water,
glycerin, castor oil, and honey. The depth h ofdipping was varied using a stepping-motor stage
moved in the vertical direction. Here, the variationin G against h at the resonance frequency wasmeasured because it corresponds to the variation in
Q-factor as long as the Q-value is high.

It has been shown that the piezoelectric
vibrator operating in a trapped-energy mode will be
a novel tool for detecting the liquid level variation
in a millimeter scale. Almost linear variation of G
against the depth of dipping has been obtained
within a few millimeter ranges. Further
investigation is required for clarifying the effects ofhydrophilicity and surface tension of the liquids on
the sensing. The use of thickness-shear vibration
modes might be more convenient for the liquids
having higher viscosity, and is under investigation.
References
1. G.. A. Campbell and R. Mutharasan.: Sensors
and Actuators A 122 (2005) 326.
2. W. Shockley, D. R. Curran, and D. J. Koneval.:
Proc. 17th Frequency Control Symposium (1963)88.

2P2a-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 213- 214
11-13 November, 2008

Target Ranging by Using Ultrasonic Adaptive Signal
and Pulse Compression
超音波適応信号とパルス圧縮を併用した距離測定
Ryo Toh1†, Dai Chimura2 and Seiichi Motooka1 (1Facult. Eng., Chiba Inst. Tech.;2
Graduate School Eng., Chiba Inst. Tech.)陶良1†，千村大2，本岡誠一1 （1千葉工大 工; 2千葉工大 院）

1. Introduction
Ultrasonic pulse-echo method is widely used
for target ranging, especially in water or in air
where testing environment is not suitable for opticalor electromagnetical waves, such as remote sensingof automobile and robot etc. In order to augment
both the range resolution and the signal to noise
ratio (SNR), pulse compressing technique using
coded pulse with long duration is employed. Twokinds of pulse coding methods are commonly used,such as phase coding and frequency modulation(FM). In this paper, the compression of frequency
modulated pulse is discussed.
Usually, the linear frequency modulated wave
(chirp wave) is used, and the matched filtering
method which calculates the cross-correlation of thereceiving signal with the transmitting signal isemployed for the pulse compression.[1,2] However,
especially in the application of ultrasonic wave, theeffective bandwidth of receiving signal is affectedby the restriction of the sensitivity of sensors.
In order to acquire broader bandwidth withflat spectral amplitudes, an adaptive transmitting
wave, which equalizes the affect of sensitivities of
sensors, is proposed.[3] The effectiveness ofadaptive signal is verified by an example of target
ranging in air.
2. Adaptive transmitting signal
Neglecting noise, the spectrum of receiving
signal Sr(ω) can be written as(1)
S r (ω ) = S t (ω ) ⋅ R(ω )where St(ω) and R(ω) are the transmitting signal
and transmission function including the sensitivities
of both transmitter and receiver, respectively.
If we use an adaptive transmitting signal
Sta(ω), signal with flat spectrum amplitudes can bereceived theoretically. It is given as
S r 0 (ω )S ta (ω ) =⋅ S t 0 (ω ) (2)22
S r 0 (ω ) +α2 ⋅ S r 0 (ω ) max
where Sr0(ω) is the reference receiving signal by-----------------------------------------------------------† Email: liang.tao@it-chiba.ac.jp

using St0( ω ) as transmitting signal, α is thestabilization factor to restrain the divergence of the
response function at where the value of Sr0(ω) issmall.
3. Experiment conditions and methods
The arrangement of sensors and target isshown in Fig.1. Two ultrasonic transducers with 1.5
cm in diameter and a 40 kHz resonant peak areemployed as transmitter and receiver, which are set
at (15, 30, 0) (x, y, z in cm in the coordinates shownin Fig.1, and same in following) and (-15, 30, 0),
respectively. A 5 cm x 5 cm square steel plate isemployed as measuring target. The y=0 plane isground surface where reflection should be taken
into consideration.
yTransmitterx

Targetz

ReceiverFig.1 Arrangement of sensors and target.

The chirp wave and the reference receiving
signal reflected by the target at (0, 30, 100) are
shown in Fig.2. Calculated with them, the adaptive
signal and the corresponding reference receiving
signal reflected by the same target is shown in
Fig.3.
(a)(b)

Fig.2 (a): Chirp wave; (b): Reference receiving signal.

It’s shown that unevenness is brought forth
by the compensation in the spectrum of adaptive
signal comparing to the flat range of chirp wave,
while the spectrum of receiving signal iscompensated to be flatter and broader. Here, theamplitudes of the two kinds of transmitting signals
are normalized according to their envelope areas.
The effectiveness of pulse compression using
adaptive signal is studied experimentally by setting
the target to (0, 50, 100) and (0, 10, 100). Though
the positions are symmetric to the sensors, theaffect of reflection from ground can be shown in thelower arrangement.

(a)pulse width in its waveform, comparing to those ofadaptive signal.
In Fig.6, the positions of pulse propagatingtime via the target directly, together with that beingreflected once by the ground surface (path lengthsof transmitting wave reflection and receiving wave
reflection are same owing to that the position of thetarget is set at the center of transmitter and receiver)are also shown. The ground surface reflection
shows larger amplitude because of the directivity ofthe target reflection and double paths summation. In
the result of chirp wave, the interference of two
pulses causes error at the direct reflection, while inthat of the adaptive signal they are distinguishedclearly.

(a)

(b)
(b)
Fig.3 (a): Adaptive signal; (b): Reference receiving
signal.

4. Results of Measurement
Fig.4 shows the comparison receiving signals
using chirp wave and adaptive signal astransmitting signals, while the target is set at (0, 50,
100). Fig.5 shows the compressed pulses calculated
by cross correlation of receiving signals shown in
Fig.4 with those corresponding reference receiving
signals shown in Fig.2 (b) and Fig.3 (b),respectively. Fig.6 shows the comparison pulse
compression results while the target is set at (0, 10,
100).

(a)

(b)

Fig.4 Receiving signals of target at (0, 50, 100)
corresponding to (a): Chirp wave; (b): Adaptive signal.

In Fig.5, the effectiveness of adaptive signal
is shown clearly. Because of the unevenness in the
spectrum of receiving signal shown in Fig.4 (a), thecorrelation result of Fig.5 (a) shows a narrower
bandwidth in its spectrum and more expanding

Fig.5 Results of pulse compression of target at (0, 50,100) corresponding to (a): Chirp wave; (b): Adaptive
signal.

①

②

①

(a)

(b)

②

Fig.6 Results of pulse compression of target at (0, 10,100) corresponding to (a): Chirp wave; (b): Adaptive
signal. (①:direct reflection; ②: once ground reflection)

6. Conclusions
By using adaptive transmitting signal, thespectrum of receiving signal is compensated to be
flatter and broader, which brings forth better
resolution in the result of pulse compression. The
effectiveness of adaptive signal in improving theaccuracy of target raging can be expected.
References
1. E. Ha, Y. Kawamura, et al. Jpn. J. Appl. Phys. 47(2008) 3946.
2. K. Toiyama, T. Hayashi, and S. Kamiya. Proc.
Symp. Ultrason. Electron., 26 (2005) 441.
3. D. Chimura, R. Toh, and S. Motooka. Proc. Natl.
Autumn Meet. Acoustical Society of Japan,
2008, No. 2-Q-28 [in Japanese].

2P2a-20

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 215- 216
11-13 November, 2008

A Hydrogen Sensor using Ultrasonic
超音波を用いた水素センサーに関する研究
Yoshimine Kato (Facult. Eng., Kyushu Univ.)
喜峰 （九大工）

Abstract
A hydrogen sensor using ultrasonic wasstudied. Sound velocity of hydrogen is about fourtimes larger than that of the air. Therefore, it ispossible to measure hydorgen contents in the air bymeasuring the sound velocity. We have showedthat it is possible to measure up to near 100ppm
hydrogen content in the air by measuring the soundvelocity at 330kHz of ultrasonic.
1. Introduction
Using hydrogen gas as a new fuel isimportant for clean-energy society that does not
emmit CO2, NOx, and etc. Especilally, fuel cells
and hydrogen gas vehicles are widely studied anddeveloped. Therefore, hydrogen sensors for those
applications are very important and will be widly
used for safety.
Currently, many kinds ofhydorgen sensors were developed and used today.
For example, solid state sensors[1], electrochemicalsensors,
catalytic
sensors,
metal-oxide
semiconductor sensors[2], ball surface acoustic
wave hydrogen sensors [3],and etc arecommercially available or studied.
However,some of those sensors require high temperature or
the response time is relatively slow as the order of
seconds. Also, many of these sensors cannot
distinguish hydrogen from other flammable gases
such as methane, propane and butane gases.
The sound velocity of hydrogen is about fourtimes larger than that of the air. Therefore, in thisstudy, we have showed that it is possible tomeasure hydrogen contents close to 100 ppm in the
air by measuring sound velocity changing.
2. Theory and Experiment
When there is hydrogen content of ρ vol.%in the dry air which mass is 28.96, the soundvelocity is expressed as vH,

vH =

kRT
28.96(1 − ρ ) + 2.016 ρ(1)-----------------------------------------------------------E-mail: yoshimine.kato@zaiko.kyushu-u.ac.jp

where k is specific heat ratio, R is gas constant andT is temperature in K. To obtain the hydrogenconcentration ρ in the dry air, one could measure
the sound traveling time difference ∆t between thedry air and the hydrogen contained dry air with thefollowing equation.

ρ=

28 .96t − ∆t 2{1 − () }26 .94t(2)

By obtaining the ratio of the sound traveling time inthe dry air t and the traveling time difference ∆tfrom eq. (2) as shown below,

∆t
26.94
= 1− 1−
ρ
t
28.96

(3)

one could plot the curve as shown in Fig. 1.
0.8
Sound traveling time ratio
∆ｔ／ｔ

加藤

0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

ρ: Hydrogen concentration in the dry air

Fig. 1 Dependence of the hydrogen concentration ρin the dry air, to the ratio of the sound traveling time inthe dry air t, and traveling time difference ∆t between
the dry air and the hydrogen contained dry air
according to eq. (3).

From Fig. 1. one can see that ∆t/t and ρ has
almost linear relation at lower hydrogenconcentration, therefore; it is simple to detect low
concentration hydrogen by measuring the travelingtime difference ∆t.
For measuring ∆t, an Ultrasonic Pulsar andReceiver (Japan Probe JPR-10bB) at 330kHz wasused. A number of pulses was varied form one tofour and their voltages were varied form 50 to 200V.
Two standard ultrasonic probes were used fortransmitting and receiving the pulse. Distance of
these two probes was varied from 20 to 54 mm.

(a)With H2

Intensity

0.5

Without H2

0
0

20

40

60

80

100

120

140

-0.5
-1

Time（µsec）

10.5
Intensity(b)With H2
Without H2

900

Hydrogen conc. (ppm)

1

700
600
500
400
300
200
100
0
0.00 0.01 0.02 0.03 0.04 0.05 0.06

0
75

76

77

78

79

80

81

82

83

84

∆t (µsec)

85

-0.5
-1

800

Time（µsec）

Fig.2(a) Signal intensity form the ultrasonicreceiver. Four pulses of sound wave traveled after
28mm of distance are shown. (b) Enlargement ofFig. 2(a).

3. Results and discussions
Fig.2 shows the experimental result using the
Ultrasonic Pulsar and Receiver. Signal intensitiesof the four pulses sound wave traveled after 28mm
are shown. Solid line shows received signal of thehydrogen mixed air and dashed line shows thesignal from just the air.
Fig. 2(b) is theenlargement of Fig. 2(a). ∆t the traveling timedifference between the air and the hydrogencontained air can be measured as about 0.4 µsec
form Fig. 2(b), and assuming that the soundtraveling time in the dry air t is about 80 µsec, one
can calculate the hydrogen concentration of about
1% from eq. (2). This result was about the samevalue with the measured hydrogen concentration
using a conventional H2 sensor.
Next, ppm order hydrogen concentration
measurement was tried.
The traveling timedifference ∆t between the air and the hydrogencontained air was able to be measured as small as
0.01 µsec, thus the hydrogen concentration was
calculated to be about 140 ppm as show in Fig. 3.
Fig. 3 shows estimated hydrogen concentrationfrom the measured ∆t according to eq. (2). The
transmitting pulse was one pulse and distance to areceiving probe was 54 mm. These results suggestthat it is possible to measure hydrogenconcentration by ultrasonic up to near 100 ppm and
if one can increase the ultrasonic frequency or

Fig. 3 Hydrogen concentration derived form eq. 2
with the measured ∆t: the traveling time difference
between the air and the hydrogen contained air.

distance between transmitting and receiving probes,
this limitation can be lowered.
The time for detecting hydrogen can be also
faster than conventional H2 sensors. It takes only
about 1 or 2 µsec to convert an electrical signal to asound signal or vice versa in the transmitting andreceiving probes. Additionally, it takes less than
150 µsec for sound to travel between the probes ofwhich distance is less than 50mm, for example.
4.

Summary

In this study we developed a hydrogen sensor
using the large sound velocity difference between
air and hydrogen. We have showed that it ispossible to detect hydrogen concentration up to near
100 ppm with the order of µsec.
Acknowledgment
Author would like to thank M. Inoue, H.
Baba and K. Ohira for their help in the experimentand discussion. This work was supported by
CASIO Science Promotion Foundation, and Japan
Science and Technology Agency (JST) digging
seeds program.
References
1. C. Christofides and A. Mandelis, J. Appl. Phys.
68 (1990) R1-R30.
2. S. Patel, K. Wise, J. Gland, M. Zanini-Fisher and
J. Schwank, Sensors and Actuators B 42 (1997)
205-215.
3.. T. Nakatsukasa, S. Akao, T. Ohgi, N. Nakaso, T.
Abe and K. Yamanaka, Jpn. J. Appl. Phys. 45(2006) 4500-4504.

2P2a-21

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 217- 218
11-13 November, 2008

More Precise Estimation of Capacitance Ratio
in Electromechanical Coupling System
電気機械結合系における容量比の更に精密な評価
Michio Ohki (Natl. Def. Acad.)

大木 道生（防大）1. Introduction
The estimation of capacitance ratio C/C0, definedin the equivalent circuit shown in Fig. 1(a) with C =Σl =1 Cl, is important theoretically and practically forthe following reasons: (i) The electromechanicalcoupling coefficient k2 is related with C/C0: In thequasi-static situation shown in Fig.1(b), the ratio ofelastically stored energy to electrically inputted energy, or the ratio of dielectrically stored energy tomechanically inputted energy, leads to k2(qs)= C/C0
for longitudinal (L-) effect and k2(qs)= (C/C0)/(1+C/C0) for transverse (T-) effect, where ‘(qs)’ indicates ‘quasi-static.’ (ii) Although different values of
C/C0 are actually estimated on different modes(more than one mode), the estimates of C/C0 should
be identical theoretically regardless of the observed
modes. This nature can be utilized for the reductionof errors in the lumped-parameters obtained fromthe observation of the admittance loops.1) Therefore,
it is desired to pursue more precise estimation formula for C/C0.
When the nth mode is observed, as shown in Fig.
1(c), C’0 is observed instead of C0, where(1)
C 0′ = C 0 m g n C(upper sign for L-effect and lower sign for T-effect).
Therefore, it is necessary to estimate gn (dependingon the mode number n even theoretically) more precisely. Conventionally, gn has been estimated only
from capacitance components Cl (l > n) higher than
the nth mode. In this study, the correction of gn isinvestigated, which reduces the errors of the estimates. Since an inference process is needed to determine gn, the influence of the misjudgment of theinference is also discussed.

First, we define the following quantities on thenth mode: ωn = ωA (electrical anitiresonance frequency) for L-effect, or ωn = ωR (electrical resonance frequency) for T-effect; ω'n = ωR for L-effect,or ω'n = ωA for T-effect; Yn∝(Ln)−1, resonance intensity of the nth mode, from whichŶ  ∑ Ŷ m.
mmechanical resonance shown in Fig.2. Conventionally, Llow is neglected as Llow→∞, and Chigh = Σl > n
Cl , which leads tog nconv 

2. Formulation for Correcting gn

Ŷ n  82 Yn2 , nFig. 1 (a) Lumped-parameter equivalent circuit. The
switch SWDP is opened for L-effect and shorted for
T-effect. (b) In the quasi-static situation (with mechanical terminal). (c) When the nth mode is observed.

(2)

In eq. (1), gn is derived from the circuit near the nth

C − ∑l≤n Cl
Ŷ − ∑l≤n Ŷ l

,
C
Ŷ

(3)

where the subscript stands for ‘conventional.’ The
value of Y^ is appropriately inferred from finite values of Y^m actually observed, using the nature which
the combination of resonance frequencies and intensities (‘resonance pattern’ in the frequency domain) should follow.2,3) We can calculate an estimate of capacitance ratio, denoted by rn, on the nthmode, using the obtained data of ωn, ω'n, Yn and theinferred value of Y^. 1)
In this study, lower capacitance and inductance2. M. Ohki: Jpn. J. Appl. Phys. 44(2005) 4509.
3. M. Ohki: Jpn. J. Appl. Phys. 46(2007) 4679.
4. M. Ohki: Cho-onpa Techno 18 (2006) No.5, 1.
Table I Correction of gn.
ngn(conv)Δgn(low)1
0.53473020.20274−0.1822130.13052−0.2321450.10371−0.09367

Fig. 2 Near the nth mechanical resonance.

Δgn(high)
0.13900
0.04595
0.02651
0.05868gn(corr)
0.67372
0.06648−0.07512
0.06872

components than the nth mode, which constitute
Llow, and higher inductance components, which areincluded in Chigh, are considered to correct gn. Then,
gn is corrected as

g n ( corr ) = g n ( conv ) + Δg n ( low ) + Δg n ( high ) ;n −1

Δg n ( low ) = ∑
l =1

Yˆl
Yˆ

( )

1 − ωωnl2, Δg n ( high )

(4)

( ) .
= ∑
1− ( )n′l = n +1

ωn 2 Yˆl
ωl
Yˆ

ωn 2
ωl

rn is corrected by replacing gn = gn(conv) in the formula in ref. 1 with gn = gn(corr).
3. Numerical Examples

A sample of a “nonstandard” boundary condition,
denoted by #1, is prepared, the admittance of whichis calculated with Mason’s equivalent circuit (withtransmission lines), and the foregoing formula isapplied to obtaining rn, which is compared to thevalue of C/C0 (independent of n) set on Mason’s
circuit. For lack of space, see ref. 4 for further details about boundary condition of #1.
On the modes of n = 1 to 5(= nmax) of this sample(n = 4 is not driven), gn is corrected, as shown in
Table I, where we set n’= nmax +2 in Δgn(high) for
practical reason. The errors between estimated rn(using ωn and ω'n of six significant digits) and true
value of C/C0 are evaluated before and after the correction of gn, which are shown in Fig. 3. On thewhole, the errors are reduced after the correction.
Next, the influence of misjudgment of Y^ on theerrors of the estimate of capacitance ratio is evaluated. As shown in Fig. 4, as the error of Y^ is larger,
the mean square error of rn over n = 1 to nmax also
becomes larger, but the variance of the error of rn
over n = 1 to nmax is almost unchanged and still
small. This fact means that, when the present estimation method is applied to the correction of
lumped parameters Ln using the “principle of least
variance” on rn discussed in ref. 1, this method is^ which is prefrobust against the misjudgment of Y,
erable for that purpose.
References
1. M. Ohki: Jpn. J. Appl. Phys. 47(2008) 4029.

Fig. 3 Errors of the estimated capacitance ratio
before and after the correction of gn, in the cases of(a) L-effect and (b) T-effect for #1.

Fig. 4 Dependence of the root-mean-square error(RMS) and standard deviation of error (SD) of the estimated capacitance ratio on the error of inferred Y^,
before and after the correction of gn.

2P2a-22

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 219- 220
11-13 November, 2008

Improvement of Impulse Response of Loudspeaker
Based on Equivalent Circuit Model
等価回路モデルに基づくラウドスピーカのインパルス
応答の改善
Syunji Inoue‡, Naoto Wakatsuki, Koichi Mizutani (Univ. Tsukuba)
井上俊二‡，若槻尚斗，水谷孝一（筑波大院・シス情工）

1. Introduction
An impulse response of loudspeaker has aresonance characteristic in auditory area. While theexistance of resonance contributes actively toefficient electro-acoustic conversion, the existanceof resonance causes deterioration of sound quality
especially when input signal is very short like aburst signal. This feature of the loudspeaker is aproblem when the burst signal is used for acoustic
measurement1, 2).
In this paper, we propose the system for
improvement of impulse response of theloudspeaker. The system consists of passive
electrical elements, operational amplifier, anddesigned based on an equivalent circuit model ofthe loudspeaker3, 4).
2. Equivalent circuit model of loudspeaker
Figure 1 is an equivalent circuit of theloudspeaker. Synthetic impedance of the equivalentcircuit area is given by
Z = RE +1
Rm + Ra
Mm + Ma
1+ jω
+Bl E Bl m
Bl E Bl mj ω Bl E Bl m S m

2. Transfer function
Equation (2) is transfer function of theequivalent circuit. Equations (3) are impulse
response of the equivalent circuit. Equations (3) arecalculated from Eq.(2) by Laplace transform.
Equations.(3) are the impulse response of vibration
velocity of diaphragm. Vibration velocity ofdiaphragm is not proportional to acoustic pressure.
Acoustic pressure is proportional to vibration
acceleration of diaphragm. So impulse response ofvibration acceleration of diaphragm is given by
Eq.(4).
V 1
1
1
1
= ⋅
G= m = ⋅BlE ⎛Ei BlE ⎛Rm +Ra
1⎞
Mm +Ma1 ⎞⎟+1RE⎜⎜R+ jωM+ ⎟⎟+1
+ jω
+
RE⎜⎜
jωS⎠
BlEBlm jωBlEBlmSm ⎟⎠⎝⎝ BlEBlmα=

RE R + 1
2RE M

,β =

⎛ R R + 1⎞
1⎟−⎜ E
MS ⎜⎝ 2 R E M ⎟⎠(2)2

g (t ) =⎛⎞1αe − αt ⎜⎜ cos βt − sin β t ⎟⎟Bl E R E M
β⎝⎠g& (t ) =⎧⎛ α 2⎫⎞
1− β ⎟⎟ sin βt − 2 cos βt ⎬e −αt ⎨⎜⎜BlE RE M
β
⎠
⎩⎝
⎭

(3)

(4)

(1)

where LE is ignored and the acoustical system isincluded in the mechanical system because
efficiency of the mechanical system is much bigger
than efficiency of the acoustical system. However,Eq.(1) is enough to describe the impedance of theloudspeaker as for the resonance area. Figure 2 isequivalent circuit in the resonance area which issimplified based on Eq.(1) and estimatedparameters. Figure 3 is experimental result andequivalent circuit in the resonance area. We
estimate parameters of the equivalent circuit using
electric impedance method.

Fig.2 Equivalent circuit in resonance area.

Fig. 1 Equivalent circuit of loudspeaker.
------------------------------------------------------------

Fig.3 Impedances of an actual loudspeaker and its
equivalent circuit.

inoue@aclab.esys.tsukuba.ac.jp

Fig.6 System for improvement of impulse responseof loudspeaker.

Fig.4 Impulse response of loudspeaker andequivalent circuit.

Fig.7 Simulation of impulse
loudspeaker based on the system.
G=

Fig. 5 Frequency response of loudspeaker andequivalent circuit.
Figure 4 is acoustic impulse responses of theloudspeaker and transfer function of the equivalentcircuit. Using each of the maximum amplitude,
Fig.4 is normalized. Figure 5 is frequency responseof Fig.4. Figure 5 shows that we can use thetransfer function of the equivalent circuit as transfer
function of the loudspeaker in the resonance area.
4. System for improvement of impulse responseof loudspeaker
Figure 6 is the system which we propose for
improvement of the impulse response of theloudspeaker. The idea of the system is that wecontrol RE in Eq.(2) using equivalent circuit which
can make a same output as an actual loudspeaker.
As a result β becomes 0 and the impulse response
does not resonate. Transfer function of the system isEq.(5). Equations.(6) are impulse response of thesystem. Equation.(7) is impulse response ofvibration acceleration of diaphragm. When β is 0, X,
A and impulse response are Eqs.(8). Figure 7 issimulation of the impulse response of theloudspeaker based on the system in the case R1=1 Ω
and R2=50 Ω. Figure 7 is normalized using the
maximum amplitude of Eq.(4).

X=

response

of

1
Vm
R2
=
⋅
Ei BlE ( R1 + R2 − AR1 ) RE (R1 + R2 ) + R1R2 ⎛1 ⎞⎟ +1⎜ R + jωM +R1 + R2 − AR1 ⎜⎝jωS ⎟⎠(5)

RE (R1 + R2 ) + R1 R2
R1 + R2 − AR1g (t ) =XR + 1
1 ⎛ XR + 1 ⎞
−⎜
,β =
⎟
2 XM
MS ⎝ 2 XM ⎠

2

⎛
⎞
α
e − αt ⎜⎜ cos βt − sin βt ⎟⎟Bl E ( R1 + R2 − AR1 )β⎝⎠g& (t ) =

X =

,α =

R2

⎧⎛ α 2⎫⎞R2e −αt ⎨⎜⎜− β ⎟⎟ sin βt − 2 cos βt ⎬Bl E ( R1 + R2 − AR1 )
⎠
⎩⎝ β
⎭

MS
2M − R MS β = 0

g& (t ) →,A=

1{( X − RE )(R1 + R2 ) − R1 R2 }
R1 X
β =0

R2
e − αt α 2 − 2
Bl E ( R1 + R2 − AR1 )

(

)

(6)
(7)

(8)

5. Conclusions
We propose the system for improvement of
the resonance characteristic in the impulse responseof the loudspeaker. The idea of the system is that
we control RE in Eq.(2) using the equivalent circuit.
Then, we establish that the system is useful for
improvement of the impulse response of theloudspeaker.
References
1. I. Odanaka et al.: Proc. OfICSV12, (2005) 361.
2. I. Saito et al.: Jpn. J. Appl. Phys. 47 (2008) 4329.
3. K. Satoh et al: Audio Eng. Soc. 107th
Convention, Preprint (1999) 5023.
4. W. Klippel, U. Seidel: Audio Eng. Soc. 110th
Convention, Preprint (2001) 5308.

2P2b-10

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 221- 222
11-13 November, 2008

Improvement of Reflection Point Search by Rectangular Sound Source
through Introducing Array with Small Number of Element
矩形音源による反射点探索の少数要素アレイの導入による改善
Hiroyuki Masuyama1‡ and Koichi Mizutani2 (1 Electron. Mech. Eng. Dep., Toba Nat.
Col. of Mar. Tech.; 2 Grad. Sch. of Sys. Info. Eng., Univ. of Tsukuba)
増山裕之 1‡，水谷孝一 2 （1 鳥羽商船高専・電子機械工; 2 筑波大院・シス情工）

1. Introduction
In measurement and imaging using ultrasonicwaves, a rectangular transducer is widely used as anelement of array sound sources. By the effect offour vertices and four sides, the spatial impulse response of the rectangular transducer complicatedly
changes in proportion to the position of the observation point of the sound wave1). Therefore, thewaveform, that is acquired by driving the soundsource actually, also changes with the dependence
on the position of the observation point.
Here, a method that searches the position of
the reflection point is examined, by analyzing thechange of the waveform of the reflected wave froma point reflector, which depends on the position of
the reflection point. By introducing a rectangulartransducer array with small number of element as asound source, and forming multiple rectangularsound sources in which the configuration differs, itaims at the improvement on the search result fromthe method using single rectangular sound source2).
2. Theory for Searching Reflection Point
As shown in Fig. 1, a coordinate system including a rectangular transducer array sound source
and a point reflector is considered. As a soundsource, the rectangular transducer array with fiveelements is assigned in the cruciform to a plane thatis perpendicular to the z-axis so that the center inthe central element is the origin of the coordinates.
The dimension of each element is (b2−a1) × 2a2(element 1 and 3), 2a1 × (b1−a2) (element 2 and 4),
and 2a1 × 2a2 (element 5), respectively. The position of the reflection point is indicated by P(r), and,
when calculation results are shown, r is expressedusing the distance from the center of the soundsource (|r|), the azimuth angle (azim.), and the elevation angle (elev.).
When the sound source is driven with uniform velocity v(t), the output e(r, t) received at thesound source as a result of the reflection at point
P(r) can be expressed by the following equation3):kρA∂∂e(r , t ) = −v(t ) ∗ h(r , t ) ∗ h(r , t ),
(1)
2c
∂t
∂t
where k is the proportionality constant, ρ is the-----------------------------------------------------------e-mail address: masuyama@toba-cmt.ac.jp

y

P(r)
2b2

2a1

2a2

|r|

x

O

2b1

elev. anglezazim. angle

Fig. 1 Geometry of the coordinate system, rectangulararray sound source and a reflection point P.

( cT2 + a +b ,Pmax1 rmax = max

y

2
1

2
1

cT
+ a22 +b22
2

b2

cT
2

)

Pmax2

a1

x

2
1

b1
a2

3 5
4

cT
2

cT
Pmin rmin = 2

zFig. 2

Calculation range of the distance |r|.

density of the propagation medium of the soundwave, A is the area of the region in which the reflection point contributes to the reflection, h(r, t) is
the spatial impulse response of the sound source,and ∗ denotes the convolution integral.
Since v(t) is known, and since the rise time of
the reflected wave is measurable, the value of |r|can be determined in a certain range. The region isshown in Fig. 2. When the rising time of the reflected wave is T and the velocity of sound is c, theshortest distance between a certain part of the soundsource and the reflection point P(r) becomes cT/2.
When cT/2 is adopted as the distance from the center of the sound source, |r|, the minimum andmaximum value of |r| are obtained when the reflection point P(r) is located on Pmin and, Pmax1 or Pmax2
in Fig. 2. When the value of r is set in an appropriate interval in this range, the spatial impulse re-

15

15

15
0

30

45 0

15

30

45 0

15

elevation angle (deg.)

30

30

15

45

30

45

30

45

(c) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 10, 10)

1(1) |r| =(2) |r| =(3) |r| =13.250(mm)13.500(mm)13.750(mm)(a) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 30, 30)450(b) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 30, 10)0correlation coefficient (normalized): −1

1(1) |r| =(2) |r| =(3) |r| =13.250(mm)13.500(mm)13.750(mm)(a) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 30, 30)0(b) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 30, 10)

45
30
15
0

(c) P(|r|(mm), azim.(deg.), elev.(deg.) = P(13.500, 10, 10)

45

30

30

15

15

0
45

0

15

30

45 0

15

30

45 0

15

elevation angle (deg.)correlation coefficient (normalized): −1

30

0
45

azimuth angle (deg.)

azimuth angle (deg.)

Fig. 3 Calculation results of cross-correlation coefficients: calculated using five-element rectangular arraysound source.

Fig. 4 Calculation results of cross-correlation coefficients: calculated using single rectangular sound source.

sponse h(r, t) corresponding to each r can be obtained, and the output waveform e(r, t) in eq. (1) ateach r can be calculated. By deducing thecross-correlation coefficient between the waveform
obtained by the calculation and the original (acquired) reflected wave in the sequential order, it
becomes possible to estimate the position of reflection point r.

was achieved, when single element sound source
was used. There is an aspect that the position of thereflection point is searched, when the array soundsource is also used. In contrast, in Fig. 3(c), there
are many areas of high correlation and inverse correlation except at the reflection point, and there isan aspect of which the search result is not improved.

3. Numerical Calculations
Figure 3 illustrates the results confirmingthat the search by the above-mentioned technique ispossible. Each result is obtained by calculatingv(t)∗(∂/∂t)h(r, t)∗(∂/∂t)h(r, t) in eq. (1), and calculating the cross-correlation coefficient at time zerowith the calculation result for the points around located reflection points. The dimensions of the arrayelement used for the calculation are a1 = 6.45 mm,
a2 = 4.85 mm, b1 = 10.05 mm, and b2 = 9.95 mm,
respectively. Using each of element 1, 3, and 5, andelement 2, 4, and 5 in Fig. 2, two kinds of the rectangular sound source in which the configurationdiffers are formed. Then, the correlation coefficientis calculated in each sound source, and the average
is taken. For the comparison, the calculation result
using a single rectangular element of dimension
2a1×2b12) is shown in Fig. 4.
In Fig. 3(a), the result with high correlation
except at the reflection point (solid circular mark ineach subfigure), obtained when the single element
was used (shown in Fig. 4(a)), is not conspicuous,and seemed to improve the search result. The reflection point shown in Fig. 3(b) is what the search

4. Summary
In the reflection point search using rectangular sound sources, a rectangular transducer arraywith small number of element was introduced, andthe improvement on the search result was attempted.
Results of numerical calculations show that there is
the position where the search result is improved.
However, the position where the search result is not
improved also exists. In order to attempt the improvement on the search results, it is necessary to
conduct further examinations with respect to theconditions of the reflection point and soundsources.
Acknowledgment
This work was supported in part by a Grant-in-Aid for Young
Scientists (B) (No. 19760280) from MEXT, Japan.

References
1. J. L. San Emeterio and L. G. Ullate: J. Acoust. Soc. Am. 92(1992) 651.
2. H. Masuyama and K. Mizutani: Jpn. J. Appl. Phys. 46 (2007)
7793.
3. J. P. Weight and A. J. Hayman: J. Acoust. Soc. Am. 63(1978) 396.

2P2b-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 223- 224
11-13 November, 2008

Visualization of Lamb-Type Waves in Glass Plates
Using Pulsed Light Source
パルス光源を用いるガラス板内 Lamb－Type Wave の可視化
Kojiro Nishimiya‡, Koichi Mizutani, Naoto Wakatsuki, Takeshi Ohbuchi (Univ.
Tsukuba) and Ken Yamamoto (Kansai Univ.)
西宮康治朗‡，水谷孝一，若槻尚斗，大淵武史（筑波大院・シス情工），山本

1. Introduction
Visualizing sound waves is very important inorder to understand the condition when the soundwaves propagate in various mediums. In recent
days, many visualizing methods have been
investigated1). These results contribute tonondestructive test2,3), medical fields as shown in
the acoustic focusing lens , and so on.
In this study, the visualizing method using
photoelasticity is used for observing the stress ofelastic waves in the elastic body. Particularly, we
considered Lamb-type waves in the elastic plates.
The waves in layer structure are observed. Amongthem, the condition that the layer changes on theway is very interesting. In this condition, not only
the Lamb-type waves but also the wave propagating
along the boundary exists at the same time. In thisstudy, we can observe these multiple elastic waves
at the same time. This boundary wave is slower
than the simultaneous Lamb-type waves because
the energy of the wave is trapped around theboundary surface. These visualizing results can use
for understanding of the behavior of the soundwave in the elastic body.
2. Visualization
Conditions

SystemandExperimental

Figure 1 shows the visualization systems of
the sound waves. In this system, the stress in theelastic plates is visualized using the birefringenceeffect arisen from ultrasound stress, through two
orthogonal polarization plates. We show thephotoelastic optical system and visualization imageof the elastic wave in Fig. 2. Polarizer and Analyzer
are orthogonalized and tilted at 45˚ to the
propagation direction of the elastic wave as shownin Fig.2 (a). Herewith, absolute difference of stress|Txx-Tzz| are visualized. Additionally, by slightly
deviating the angle between the polarizer andanalyzer from the completely orthogonal condition,
the stress difference Txx-Tzz is visualized.
-----------------------------------------------------------nishimiya@aclab.esys.tsukuba.ac.jp

健（関西大）The visualized image is shown in Fig. 2 (b) and (c).
At this time, the stop motion is obtained by using
the pulsed light source synchronized to ultrasoundincidence. The transient response is obtained byusing the delay time between the light emission andthe ultrasound incidence.
In this study, Lamb and Lamb-Type waves
in glass plates are visualized. The waves in theplates are excited by the incident ultrasound inwater at a particular angle to the plates. The waves
in the plate have dispersiveness and various
propagation modes4,5,6). The modes depend on the
wavelength of the incident ultrasound, the incident
CCD Camera
Ultrasound Transducer

Function Generator
Function Generatoryzx

Elastic plates

Polarization Plate
Lens
Pulsed Light Source

Fig. 1 Visualization systems of sound waves.
z
A

P
45

(a)

Elastic Plate

o

x

y

P : Polarizer
A : Analyzer

(b)

(c)
Txx - Tzz < 0Txx - Tzz > 0

Fig. 2 Photoelastic optical system and visualized
image of elastic wave.

3. Visualization Results

Ultrasound Transducer
(a)
z

1 mm
x

y

Glass slide

(b)

(c)

Observed images of waves in the plates areshown in Fig. 4. Bright areas in the images
correspond to the high stress areas. S0 mode Lambwave or symmetrical Lamb-type wave are observedin all cases. As well as these modes, another wave
is also observed. We guess the wave is a kind ofboundary waves. The wave is slower than the Lambwave, because shear stress is interrupted by theboundary surface because the boundary surfaces
can slip. Consequently, the wavelength of theboundary wave is shorter than that of the Lambwaves. In this way, it was verified that the multiple
elastic waves exist in the elastic plate at the sametime by using visualization.

Fig. 3 Experimental setup of visualization.
4. Conclusions

λL

(a)

λL

(b)

(c)

λL
λB

z
y

We observed the multiple elastic waves inthe elastic plates by using visualization system. In
this study, we observed the Lamb and Lamb-type
waves of several conditions. Among them, we
verified that a kind of boundary waves is excited in
the condition that the layer changes on the way. The
wavelength of the boundary wave was shorter thanthat of the Lamb waves.
Visualization of the elastic wave isimportant to develop the skill in various fields.
Particularly, in the nondestructive test, the complex
elastic wave depending on the shape of the elastic
body must be dealt. In these cases, visualization isavailable.

x

λL : Wave length of Lamb wave (S0)λB : Wave length of Boundary wave
Fig. 4 Visualization results.

angle of the wave and the thickness of the elastic
plates. We observed the condition that the Lambwaves in one plate and the layer structure. Particular,
we considered the condition that the layer changes
on the way. The incident wave frequency is fixed.
Also, the glass slides are used as the elastic plates.
The thickness of the glass slides are 1 mm. In thisexperiment, we use the piezoelectric resonator thatthe thickness is 2 mm, as a transducer. As shown in
Fig. 3, oblique incidence waves are transformed
into the Lamb and Lamb-type waves and propagate
in the elastic plate. Lamb-type wave is a kind ofplate-mode waves propagating in layered
structure7,8). At this time, the excitation frequency isabout 1.07 MHz. we examined three conditions (a),(b) and (c) in Fig. 3.

References
1. Hyo Ung Li and Katsuo Negishi: Ultrasonics,
32,(1994) 243
2. H. Sato, M. Lebedev, and J. Akedo: Jpn. J. Appl.
Phys. 46 (2007) 4521.
3. Toshinobu Ito and Yasuo Kokubun: Jpn. J. Appl.
Phys. 43 (2004) 1002
4. I. Tolstoy and E. Usdin: J. Acoust. Soc. Am. 29(1957) 37.
5. K. Nishimiya, K. Yamamoto, K. Mizutani, and N.
Wakatsuki: Jpn. J. Appl. Phys. 46 (2007) 4483.
6. K.Nishimiya, Koichi Mizutani, Naoto Wakatsuki,
and Ken Yamamoto: Jpn. J. Appl. Phys. 47(2008) 3855.
7. K.Yamamoto: Proc. Symp. UltrasonicElectronics, 26 (2005) 355 [in Japanese].
8 F. Coulouvrat and M. Rousseau: Acta Acust, 84(1998) 12.

2P2b-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 225- 226
11-13 November, 2008

Reconstruction of 3D sound field from 2D sound fieldusing acoustical holography
音響ホログラフィ法を用いる二次元音場からの三次元音場再構成
Takeshi Ohbuchi1‡, Koichi Mizutani1, Naoto Wakatsuki1, Kojiro Nishimiya1 and
Hiroyuki Masuyama2 (1 Univ. Tsukuba; 2Toba Natl. Coll. Mar. Tech.)
大淵武史 1‡，水谷孝一 1，若槻尚斗 1，西宮康治朗 1,増山裕之 2（1 筑波大院シス情工; 2 鳥羽商船高専）

1. Introduction
Ultrasonic waves are widely used forindustrial instrumentation, medical diagnosis, andso on. Thereunder, it is important to measure
three-dimensional sound fields. Currently, a major
instrument for measuring the sound field is a
microphone with mechanical scannings. However,
the instrument disturbs the sound field and requires
time for measurement. So, an optical probe draws
attention. Noncontact measurement of the soundfield is possible with the opticalprobe 1).
In this paper, we propose a method for areconstruction of a radiated three-dimensionalsound field. An acoustic hologram is first obtainedusing optical computerized tomography (O-CT) 1).
Two-dimensional sound fields are then calculatedusing near-field acoustical holography 2, 3) (NAH)from the hologram. Fimally, images of sound field
are bound together, and the three-dimensionalsound field is reconstructed.
2. Principle of measurement
2-1. Reconstruction of sound fields using O-CT
We consider a coordinate system as shown in
Fig.1. An ultrasonic wave is radiated in the
direction of z-axis, and a laser is passing throughthe ultrasonic wave in the direction of y-axis. The
center of a transducer is located on origin. The laser
is influenced on a phase by the ultrasonic wave 2).
The phase change is quadrature detected using aninterferometer with linear scannings so that a single
projection is obtained. Then, projections in all the
directions are obtained by rotation scannings, andthe sound field is reconstructed using CT 1).
2-2. Calculation of sound fields using NAH
A sound field in a reconstructed plane z = z isexpressed as pCT(x, y, z). A sound field in anotherplane z = z’, pAH(x, y, z’), is calculated from theexperimental data in z=z. The relationship between
the sound fields in reconstructed and calculated
planes is given bypAH ( x, y, z ′) = pCT ( x, y, z ) ∗ h( x, y, z ′ − z ) , (1)-----------------------------------------------------------ohbuchi@aclab.esys.tsukuba.ac.jp

xyReconstructed field
Calcilated field

z=z
z=z’

Scan
Light Beam

3D Sound fieldszFig. 1 Schematic of sound velocity measurement using
Optical-CT and coordinate system.

where * and h denote convolution integral and a
propagation function. Here, the propagation
function in wavenumber domain H is expressed as
H ( k x , k y , z '− z ) = exp {ik z ( z '− z )} ,(2)

k z2 = k 2 − k x2 − k y2 ,(3)3)

where k is a wavenumber .
Thus, two-dimensional images are calculatedwith presumption of the wavenumber4), and thethree-dimensional sound field is reconstructed.
2-3. Determination of the wavenumber
To calculate the sound field using NAH, thewavenumber is determined. Two sound fields in z =z and z = z’ are reconstructed using CT, and a soundfield in z=z’ is calculated from the sound field in
z=z using NAH with a presumption of wavenumber
kAH. Then, a phase difference Φd is gained between
the reconstructed and calculated sound fields, pCT(x,y, z’) and pAH(x, y, z’) in wavenumber domain. The
relationship between the phase difference and thewavenumber is given by
2

k=

Φd
−k
+ k x2 + k y2 ,( z '− z ) zAH(4)x (mm)014(b)Calculation

140

y (mm)-14(a)

Reconstruction

-14
(c)

(d)

0

1 −π

Normalized Amplitude Phase (rad)πPhase (rad)Normalized AmplitudeFig. 2 Experimental results of reconstructed and calculated
sound fields. (a) and (b) the calculated sound fields; (c) and(d) the reconstructed sound fields. (a) and (c) the amplitude
of sound fields; (b) and (d) the phase.
1

(a)

0.8
0.6
0.4
0.2

Calculated Result
Reconstructed Result

0
π (b)

0

−π
40

41

42
43
z (mm)

44

45

Fig. 3 Reconstructed and calculated sound field on z-axis.
2
k zAH 2 = kAH− k x2 − k y2 .

(5)4)

Then, the actual wavenumber is obtained , and thethree-dimensional sound field can be reconstructed.
3. Experimental Results
A diameter of a transducer radiating an
ultrasonic wave into water is 6.0 mm, and afrequency of the ultrasonic wave is 5.0 MHz. In
water, an obstacle exists. The obstacle is a metal bar
whose diameter is 5 mm, and located at z=20 mm.
Two-dimensional sound fields in the range fromz=40 mm to z=44 mm with 1.0 mm step aremeasured by an optical probe whose light source isa He-Ne laser. The transducer is set to mechanicalx– and θ–stages and is scanned relatively to thelaser beam. A linear scanning range in x direction is-20 ≤ x ≤ 20 (mm) with 0.2 mm steps, and a rangeof rotation is 0 ≤ θ < π (rad) with π /18 rad rotation
step angles; 18 projection data are acquired. The
sound field is obtained using CT from theseprojections. A sound velocity is determined as 1508
m/s by eq. (4) from sound fields in z=40 mm andz=41 mm. The three-dimensional sound field isobtained in the range from z=40 mm to z=45 mm,that is 501 images of sound fields reconstructedusing NAH from the reconstructed sound field in
z=40 mm using CT.
Figure 2 shows an experimental result ofsound fields in z=44 mm. Circles and parallel lines
show the transducer and the metal bar, respectively.
Figs. 2(a) and 2(b) show the sound fields calculatedusing NAH, and Figs. 2(c) and 2(d) show thosereconstructed using CT. Figs. 2(a) and 2(c) shownormalized amplitudes of the sound field, and Figs.
2 (b) and 2(d) show the phases. Images of thecalculated sound field are similar to those of thereconstructed sound field, and influences by the
obstacle are expressed in Fig. 2.
Figure 3 shows an experimental result of thesound field on z-axis. Fig. 3(a) and 3(b) show thenormalized amplitude and the phase, respectively.
The solid line denotes the results using NAH, anddotted line denotes the results using CT. The
calculated result is good agreement with thereconstructed result.
4. Conclusions
The three-dimensional sound field wasreconstructed using O-CT and NAH. The soundfield was radiated into water from the circulartransducer with the diameter of 6.0 mm and driven
at 5.0 MHz, and the obstacle existed on the soundaxis.
Todeterminethewavenumber,
two-dimensional sound fields at z=40 mm and z=41
mm were reconstructed using O-CT in the region of
28 × 28 mm2. The determined sound velocity was
1508 m/s. Using NAH with the determined soundvelocity, the three-dimensional sound field in theregion of 28 × 28 × 5 mm3 was reconstructed using
NAH from the two-dimensional sound field in z=40
mm. The reconstructed three-dimensional soundfield using NAH was good agreement with thereconstructed sound field using CT. The
visualization technique presented in this paper is
expected to be applicable to an evaluation oftransducers, and so forth.
Acknowledgment
This work was supported by Grant-in-Aid for JSPS Fellows(20.581).

References
1. T. Ohbuchi et al., Jpn. J. Appl. Phys., 45 (2006) 7152.
2. E. G. Williams et al., Phys. Rev. Lett., 45 (1980) 554.
3. T. Ohbuchi et al., Jpn. J. Appl. Phys., 46 (2007) 4629.
4. T. Ohbuchi et al., Jpn. J. Appl. Phys., 47 (2008) 3959.

2P2b-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 227- 228
11-13 November, 2008

Study on the extreme shallow underground imaging using SLDVSLDV を用いた極浅層地中映像化に関する研究
Touma Abe† and Tsuneyoshi Sugimoto (Faculty of Eng., Toin Univ. of Yokohama)
杉本恒美（桐蔭横浜大 工）

2. Exploration method using SLDV
Vibration velocity at the ground surface that energizedby sound source is measured by the SLDV (Polytec
PSV400-H8). To measure the vibration velocity using
the SLDV, distance between the SLDV head unit andground surface needs more than 0.4m. The measurable
range is within ±20 degrees.
Fundamental concept of the exploration method using
the SLDV is shown in Fig.1. The difference of thevibration velocity will be expected, if a buried object
near the ground surface exists.

is measured in the laboratory. The experimental setup
is shown in Fig.2 Sand tank size is 80cm ×60cm×50cm,and average sand particle is about 300μm in
diameter. super-magnetostriction vibrator (Moritex
Corp,
AA140Jo13-MS1)
andflat
speaker(FPS2030M3P1R) were used for the vibration source
respectively. Nothing has been buried in sand. Output
waveform is burst 10cycle of sine and frequency is
300Hz. Figure 3 shows the vibration velocity change
in each frequency. Form this figure, vibration velocitychanges are seen other than the driving frequency(300Hz) when a super-magnetostriction vibrator isused as a sound source. In addition, the velocity
amplitude of the airborne wave is smaller than theelastic wave that generated by a vibrator whichcontact to the sand surface.

Fig.2 Experimental set up in the laboratory
(a)

(b)

Magnitude[m/s]

1. Introduction
Up to now, Ground Penetrating Radar (GPR) andmetal detector are used for the land mine detection.
Because a recent land mine hardly includes the metal,
these detection methods are not so effective. Besides,
these methods can not work in the marshy area andthe soil containing the electrolyte, like as the soil in
the Kingdom of Cambodia. To enable the exploration
under such a condition, the exploration method thatuses sound wave has been examined (1).
This research has a purpose of extremely shallow
underground exploration that including the land mine
detection. The vibration velocity distribution ofground surface is measured by Scanning laser Doppler
vibrometer (Hereafter, it is simplified with SLDV) (2).
This time, the comparison of elastic wave generated
by super-magnetostriction vibrator and airborne wave
generated by flat speaker are examined. Moreover,
outdoor exploration of buried object using flat speakeris examined.

magnitude[m/s]

‡

阿部冬真

2.50E-05
2.00E-05
1.50E-05
1.00E-05
5.00E-06
0.00E+00
0

100

200
Frequency[Hz]

300

400

0

100

200
Frequency[Hz]

300

400

2.50E-05
2.00E-05
1.50E-05
1.00E-05
5.00E-06
0.00E+00

Fig.3 Vibration speed vs. frequency at surface of sand(a) Used super-magnetostriction vibrator(b) Used flat speakerFig.1 Fundamental concept of exploration method
using SLDV

3. Comparison of super-magnetostriction
vibrator with flat speaker
The vibration velocity distribution of the sand surface-----------------------------------------------------------kaosunetto@gmail.com

4. Experimental exploration buried object foroutdoor
Outdoor experiments are carried out at the fallow fieldin Ibaraki prefecture. To make good coupling with thesoil, a plastic container (dia. 10cm, height 9cm) wasburied approximately one year ago. Container is filledwith sugar, because the specific gravity iscomparatively near the TNT gunpowder used for the(a)4.1 Experimental set up for outdoor
The numbers of scan points are 143, and the distance
between each point is 5cm. The buried object islocated at the center of these points. Figure 4 shows
the setup. Flat speaker is tilted at 20° for better
generation of the slow wave (3). For the cancellation of
the horizontal vibration and the emphasis of thevertical vibration, two flat speakers are facing eachother as shown in Fig.4. Output waveform used noise
wave and sine-wave burst (150Hz). The noise wave is
output for one second. The burst wave number is 50.

Reference
1. Watanabe and Iyama , MASJ, pp.1215-1216,2007
2. J.M.Sabatier, et al, IEEE Trans. Geosci. & Rem.
Sens. 39, pp.1146-1154, (2001)
3. T.Tsurumi and M.Kimura, MASJ,2-9-15,
PP.1145-1146, (2003.9)

Magnitude[m/s]Fig.5 Example images of ground surface vibration(a) Noise wave (156Hz) (b) Burst wave (150Hz)
(a)

(b)

0.000015
0.00001
0.000005
0
0

100

200
Frequency[Hz]

300

400

0

100

200
Frequency[Hz]

300

400

0.000015
0.00001
0.000005
0

Fig.6 Vibration velocity vs. frequency
at ground surface used noise wave(a) On buried object (b) Out of buried point(a)Magnitude[m/s]

5. Conclusion
For non-contact land mine detection using sound wave,
the airborne waves was compared with the elastic
waves. From the experimental results, we confirmedthat ground surface did not vibrate other than thedriving frequency in the case of the airborne waves.
Therefore, considering about the actual exploration, it
seems that the following methods are best way. First,
using the noise waves, vibration velocity distributions
at various frequencies are examined. Next, exploration
is made by the burst waves with the frequency that alarge change of the vibration velocity is observed.
The buried object respons was able to be imaged byusing both noise waves and burst waves. In this time,
two flat speakers were facing each other, we will
examine a more effective setup in the future. Fromexperimental results, the velocity amplitude became
small when the noise waves were used, therefore, wewill examine whether we cannot make more big
vibration velocity in the future.

Fig.4 Experimental set up for outdoor experiment(a) Upper view (b) Side view(a)(b)

Magnitude[m/s]

4.2 Verification of buried object response
Figure 5 shows the image of the vibration of theground surface created by each output waveform.
They are images by noise wave (156Hz) and burst
wave (150Hz of output frequency). A large vibration
velocity change is seen at the center of the scan area.
Next, to the confirm the difference of the vibration
velocity distribution, average vibration velocity offour points on the buried object and around the buried
object are compared. Figure 6 and Fig.7shows theaverage results of using noise wave, and using burst
waves, respectively. In the case of the noise waves,some peaks exist around the 150Hz on the buried
object. On the other hand, in the case of the burst
waves, a strong peak exists at the driving frequency
on the buried object.

(b)

Magnitude[m/s]land mine (specific gravity: sugar is 1.59 g/cm3, TNT
gunpowder is 1.65 g/cm3).

(b)0.00006
0.00005
0.00004
0.000030.000020.00001
0
0

100

200
Frequency[Hz]

300

400

0

100

200
Frequency[Hz]

300

400

0.00006
0.00005
0.00004
0.000030.000020.00001
0

Fig.7 Vibration velocity vs. frequency
at ground surface used noise wave(a) On buried object (b) Out of buried point

2P2b-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 229- 230
11-13 November, 2008

Study on the ultrasonic imaging at the extreme shallow
underground in submerged soil
冠水土壌中での極浅層超音波イメージングに関する研究
Kunihiko Seo, Takashi Shirakawa and Tsuneyoshi Sugimoto (Facult.. Eng., Toin Univ.
of Yokohama)
瀬尾邦彦‡, 白川貴志, 杉本恒美（桐蔭横浜大・工）1. Introduction
Now a lot of land mines remain buried in theworld, so that the clearance of them is required. As atool of removing those land mines, metallic detectors
or Ground Penetrating Radar (GPR) are often used.
However, they are not effective in Southeast Asia in
the rainy season when most of the land is flooded andchange into marshes, because electromagnetic waves
are not transmitted well in water. Therefore, using
sound waves will be profitable to detect the landmines in the flooded soil. So we have tried to detectburied object at extreme shallow underground insubmerged soil by ultrasound. Considering the landmine search, a target area is extreme shallow such asaround several cm in the depth. In previous
presentation, we tried underground imaging ofsubmerged soil in our lab. using ultrasonic transducers
driven at 50 kHz[1]. As a result, higher frequency isthought to be effective to detect the shape of buried
object. Then in this research we employ ultrasonictransducers driven at 120 kHz for improvement ofaxial resolution of images.

2. Exploration and imaging method
Our target area is extreme shallow inunderground exploration. So we employ twotransducers (For transmitter and for receiver) toseparate received signals from a input signal. However,
the receiver receives the direct wave which has huge
amplitude. For cutting the direct wave, We employ an
acoustic shielding board. Fig.1 shows the appearanceof the transducers and the shielding board. In thisresearch, transmitter and receiver are fixed as one
device.
Transmitter

Receiverplaced on the ground. Then the transmitter emits
ultrasound waves toward downward. And these waves
are reflected at the buried object. The relation between
the time in received waves and the depth of reflection
point is shown by the following equation.
2

æ vt ö æ d ö
Z = ç ÷ -ç ÷è 2ø è2ø2(1)Here, Z is the depth from the ground and d isthe distance of two transducers and v is the soundvelocity. From previous research, the velocity is
assumed to be 1500 m/s[1]. We scan transducers on the
ground in 2 dimensions at specific distance by hand.
At each recorded point, the equation above is appliedand 3 dimensional image are calculated.

3. Experimental imaging in the lab.
We make underground imaging of submerged
sand in the water tank at the lab. The diameter of sandparticles are 200-300 micrometers. The depth of waterfrom ground is around 6 cm. To record a data, a set of
the transmitter and the receiver is placed on the
ground. Then waves are transmitted and recorded.
Exploration area and measurement location are shownin Fig.2. Target object (10 cm × 15cm × 4 cm, hollow
plastic container) is buried around the depth of 10 cm
from ground level. We scanned transducers at theinterval of 4 cm by hand. And received signals arerecorded at each measurement location. Transmission
signals are 7 cycles burst waves at 120 kHz.
Calculated image is shown in Fig.3. Samenumerical value points are connected as a flat surface.
Strong waves which have higher amplitude areobserved when the transducers are placed on theburied target. As a result, rough buried point dicatedgraphically in 3D image shown in Fig.3.

Acoustic shielding board(32,40)(0,40)

Water

TargetSoil(10cm×15cm)

TargetFig. 1

Appearance of the transducers and the acoustic
shielding board

Underground images are made by B-mode
imaging method using reflected waves from a buried
target. Transducers (Transmitter and receiver) are

4cm(32,0)

(0,0)

Y[cm]

(20,0)
X[cm]Fig. 2

Exploration area and measurement location

hollow plastic container buried at 15.3 cm (a) isimaged clearly, other targets are blurring. This isthought to be caused by the characteristic of the paddy
field. The soil in paddy field is not uniform. So
ultrasound wave proceeding in the soil is thought to beattenuated or reflected diffusely. As a result, thought
image is very unstable, one target object is detected.
0m

1m

2m

3m

4m

5m

6m

Water
Ground surface

Fig. 3Calculated 3D image of undergroundWe change the material and the buried depth oftarget. Then a similar experimental exploration iscarried out. Calculated 3D images are shown in Fig.4(a). Fig.4 (b) shows a cross section in underground.
Three buried objects are detected. In this experiment,
weaker signal is observed from deeper buried object
and weakest signal is observed from buried object ofresin material. As a result, material of buried target isthought to be effect exploration.
(a)

(b)

a’

b’

c’

Containedmaterial
Depth from theground surface

Fig. 5Air

Air

15.3cm

Water

Resin

18.5cm24cm

18cm

Buried location of exploration targets

5. Discussion
As a result of the experimental imaging in thelab, buried hollow containers are detected clearly.
Although the signal from resin model is weakercompared with from hollow container, the signal ispossible to distinguish from the non-buried state.
Because the soil is ideal condition, ultrasound waves
are well transmitted and weak signal could detect. By
contrast, in the outdoor experiment at the paddy field,
signals from targets are unstable and the distinction is
impossible. Because real soil in outdoor is nonuniform,
ultrasound waves are thought to be attenuated orreflected diffusely. So countermeasures against highattenuation are necessary. Compensation of amplitude
in reflected wave by digital signal processing or
amplification of received signal by an amplifier are
thought to be effective for high attenuation. In
consideration of above, to enable the exploration in
the submerged soil in outdoor is future task.

6. Conclusions
Fig. 4(a) 3D image of underground. (b) Cross section
materials and buried depth Z[m] area’ : resin model, 10 cm. b’ : hollow container, 10 cm.
c’ : hollow container, 15 cm

4. Experimental imaging at paddy field
A similar experimental imaging is carried out at
the paddy field. We scan the transducers to one line atintervals of 5cm. The total distance of the scan line is
6 m. Hollow plastic container, container filled bywater and resin model are buried for target object. The
location and the depth of buried targets are shown in
Fig.5. Exploration result is shown in Fig.6. Although

As a result of experimental imaging in the lab,
we succeed to detect the target buried in the extreme
shallow area for underground exploration. Our
exoloration method using acoustic shielding board
enables another mehod for exploration in special
situation. However, experimental imaging in outdoor
isunstable.
For
explorationinoutdoor,countermeasures to compensate for the attenuatedamplitude are necessary.

References
1. K.Seo, T.Shirakawa and T. sugimoto: Proc. Symp.
Ultrason. Electron., 28 (2008), pp.225-226
Depth [m](a)Fig. 6

Calculated image at paddy field. One hollow container (a) is imaged clearly.

2P2b-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 231- 232
11-13 November, 2008

Resolution improvement of underground image using
pulse compression
パルス圧縮を用いた地中映像分解能の改善
Hiraku, Kawasaki†, Tsuneyoshi Sugimoto (Dept. Elect. Info., Toin Yokohama Univ.)
川﨑拓‡，杉本恒美 （桐蔭横浜大・工）1. INTRODUCTION
In order to detect the buried relics throughunderground imaging, a method by using shear
waves (1, 2) has been proposed.
In our past research, a hammer method, in which asound source is hit directly by a hammer, was used
for making underground images. Although thismethod is easy to use, improving the undergroundimage’s resolution is difficult because the frequency
and the waveform cannot be changed arbitrarily.
Therefore, we employ a super-magnetostriction
vibrator as a sound source instead of a hammer.
And we consider the pulse compression (4). The
axial resolution of underground images when usedchirp wave (300 to 800Hz, duration is 100ms) was
about 20cm in our simulation results (5).
This time, we confirm the axial resolution in theactual underground, carry out where the buried
position has already known.
2. EXPERIMENTAL SET-UP
We used the super-magnetostriction vibrator(Moritex Corp, AA140J013-MS1). To generate theshear waves, this vibrator was set on the soundsource of aluminum that is attached of spike as isshown in Fig.1. Besides, we used the geophones forthe shear waves which are the speed sensors as thereceivers. The generated sound waves are recorded
simultaneously in a seismically operationequipment (Oyo Corp, McSEIS-SX, MODEL-1125R).
The experimental setup is as shown in Fig.2.
Twelve receivers (geophones) are arranged in a line
at 0.5m intervals on the ground. The sound sources
are set between all the receivers. The output wave isa down chirp wave that oscillates from 800 to
300Hz (duration 100ms). The position of the buried
object is the center (2.75m in width, 0.5m in depth)of the exploration line. The buried object is hollow
plastic containers (width 13cm, height 12cm, depth5cm). We experiment three months after the object
buried.
-----------------------------------------------------------hot.hu2.feel.good@gmail.com
tsugimot@cc.toin.ac.jp

Fig.1 Super-magnetostriction vibrator

Fig.2 Experimental set-up

2. SIGNAL PROCESSING
The damping factor of the start frequency andstop frequency in the chirp are different. Then the
chirp signal’s spectrum of the high frequency isamplified when the filter is processed. The Fouriertransform results that are sample of received wave
and driving waveform are shown in Fig.3.
The amplitude of the received wave is less than thatof driving waveform in the frequency width of
600-800Hz. Therefore, we computed the inverse
Fourier transform after amplifying the amplitude of
600-800Hz. Then, the correlation processing isdone. The filtered processing as is shown in eq.1.
Here, fft is Fourier transform, ifft is inverse Fouriertransform, abs is absolute value.
Filtered wave =ifft { fft(Received wave) × abs (fft(Received wave))/ abs(fft(Driving waveform )) }・・・ (eq.1)
The driving waveforms, the sample of received
wave, filtered wave and waveform of correlation
result in the time domain are shown in Fig.4.
Filtered wave is looked like the driving waveform.
Then correlation result is compressed the pulse
width.

3. THE UNDERGROUND IMAGE

4.

Power spectrum

Driving waveform

0

200

400
600
Frequency [Hz]

800

1000

Fig.3 Fourier transforms results(a)Amplitude [arb.]

We produced two underground images; one byapplied pulse compression and another by hammer
method. Those images are shown in Fig.5. (a) ishammer method, (b) is underground image byPulse compression. A boundary rectangle is theburied position (2.75m in width, 0.5m in depth).
STC (Sensitivity Time Control) is the value ofcorrection for attenuation. STCT (STC Time) is thetime to apply STC. The reason of the sound speedof (a) and (b) is different is the experimental day isdifferent.
In the image the wave appeared the position that theobject had been buried. It seems that the resolution
seen from the image by the pulse compression ismuch higher than that of by the hammer method.
Axial resolution is about 0.2–0.25 m. This value isalmost the same as the simulation result (5).

Received wave

(b)
(c)
(d)

CONCLUSION

We confirm that the validity of the pulse
compression method for resolution improvement ofunderground image. In the exploration experiment,
almost the same axial resolution is obtained as aresult of the simulation. Then, it was confirmed thataxial resolution when the down chirp wave that
oscillated 800 to 300Hz (duration 100ms, applied
k-flat function) is about 0.2–0.25m in the actual
exploration experiment.
This time, duration time of chirp signals is 100ms
for the specification of the recorder that we areusing. To improve the image resolution, we will
investigate the method that the expending theduration time of chirp signals.
Acknowledgment
This work was supported by a Grant-in-Aid for
Scientific Research (B) (No.18300307) from theJapan Society for the Promotion of Science.
References
1. T. Sugimoto and M. Okujima: Jpn. J. Appl. Phys.
35 (1996) 3105-3108.
2. T. Sugimoto and H. Saitou, M. Okujima:“Archaeological Prospection”, Jpn. March.
(2000) Vpl.7 No.4, 249-261.
3. M. Moriya and T. Sugimoto: Jpn. J. Appl. Phys.
41 (2002) part 1, No.5B, 3501-3502.
4. Earth Remote Sensing Data Analysis Center(ERSDAC), “SAR processing algorithm
description”, [in Japanese] (2005)
http://www.palsar.ersdac.or.jp/guide/pdf/sar_algorithm.pdf.

5. H. Kawasaki and T. Sugimoto: Proc. Symp.
Ulttrason. Electron., Vol.28,(2007) pp.335-336
14-16 Nov. 2007.

0

0.02

0.04
0.06
Time [sec]

0.08

0.1

Fig.4 Received waves.
(a) Driving waveform, (b) Received wave,(c) Filtered wave, (d) Correlation result

(a)

(b)

Fig.5 Underground Images(a) Hammer method(b) Pulse compression

2P2b-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 233- 234
11-13 November, 2008

Poisson’s Ratio Mapping System Using Immersion
Ultrasonic Scanning
SeoYoung Oh‡, Young H. Kim, Yosub Shin 1 (Korea Science Academy), andHyun-Joon Cho (Advanced Institute of Quality and Safety)
1. Introduction
Poisson’s ratio is one of the elastic constants,
which are material parameters that relate stress andstrain[1]. Many elastic constants have been used todetermine the materials property, but Poisson’s ratio
hasn’t been given much attention due to its narrow
range[2-3]. However recently it has been reported
that Poisson’s ratio is closely related with thebonding forces and sound wave speeds in a certain
material[2]. Thus besides the classical method of
measuring Poisson’s ratio with mechanical loading,determination from longitudinal and transverse
wave speeds can be also used as a nondestructive
method. The sound wave speeds have beenmeasured seperately, each longitudinal or transverse
wave at one time, because transverse wave is hardlytransferred in liquid medium. This method had
many difficulties, which were another downsides ofPoisson’s ratio among the elastic constants, such as
pasting or removing solid couplant and damage tothe specimen during this[3]. However the mode
conversion from longitudinal wave to transverse
wave was reported with contact type longitudinaltransducer, not only at oblique incident but also at
normal angle, using liquid couplant [4].
Longitudinal and transverse wave speeds can be
Simultaneously measured using immersion method
and Poisson’s ratio can be determined frommeasured wave speeds [3].
In the present work, “μ-scan (Poisson’s ratioscan)” system which can determine distribution ofPoisson’s ratio in a sample using immersion method
has been proposed. An immersed transducer
scanned over a surface of the specimen. Wavemodes were idetified from the pulse-echo signals.
The Poisson’s ratio was determined from the transit
times of longitudinal and transverse wave modes.

⎛ λ + 2G ⎞⎟⎟c l = ⎜⎜
⎝ ρ ⎠

1/ 2

⎛G⎞
c t = ⎜⎜ ⎟⎟
⎝ρ⎠

1/ 2

(2)

and combining equations (1) and (2), we can get
2⎛ cl ⎞
2 − 2μλ⎜ ⎟ = +2=
.
⎜c ⎟
G
1
− 2μ
⎝ t ⎠

(3)

The transit times of longitudinal and transverse
wave modes are as follows:
τl =

2d
2d
,.τ t =
,
cl
ct

(4)

where d is thickness of specimen. The relationshipbetween ratio of transit times of wave modes andPoisson’s ratio is given by22⎛ cl ⎞⎛τ ⎞2 − 2μ⎜⎜ ⎟⎟ = ⎜⎜ t ⎟⎟ =.
1 − 2μ⎝ ct ⎠⎝τ l ⎠(5)

Therefore, Poisson’s ratio can be determined fromthe ratio of transit time of longitudinal andtransverse wave modes without prior information of
specimen thickness.
3. Experiment

Four specimens of Al, Fe, Cu, and brass were
employed in order to verify proposed method. Eachof them has parts of two different thicknesses asshown in Fig. 1.

2. Theoretical Background
Poisson’s ratio is defined as the ratio of lateralcontraction to longitudinal extension and therefore
can be expressed with Lamé constant as below [1].
μ=−

ε 22
λ
=
ε 11 2(λ + G )(1)

Since longitudinal and transverse wave speeds are
given as [1]1

Present address: University of Illinois at Urbana Champaign

Fig. 1 Dimensions of the specimen used in thepresent work.

An ultrasonic pulser-receiver (Panametrics 5800)
and a broadband longitudinal transducer (5 MHz
center frequency and 12.7 mm diameter) were used
to obtain pulse-echo signal. The distance fromtransducer to the top surface of specimen was about
52.5 mm. rf signals were digitized with 12 bit
resolution and 200 Ms/s.
4. Results
Typical pulse-echo signals obtained from steel
specimen are shown in Fig. 2. The echo from thesurface is referred to as “Front,” and thelongitudinal echoes from the bottom are referred toas 2P, 4P, … , and mode converted echoes 1P1S, 2S,
3P1S, …. The numbers in the front of P and S
represent the number of wave modes involved in
the echoes. Fig. 2(a) and (b) show the different timeintervals between echoes due to different thickness
at each position. The time intervals between echoes
are also different according to different materials
properties, as shown in Fig. 2(c), the pulse-echo
signals from aluminum specimen.

tone represents similar value of Poisson’s ratio,from which can be assumed that Poisson’s ratio is
the same in one material, regardless of thickness.
When the transducer passes the stepped area,
signals from both bottoms with different depths aredetected at the same time. Thus it is hard tomeasure Poisson’s ratio.
At copper and brass specimens the mode
converted echoes were not evident enough to belocated and therefore were difficult to obtain
Poisson’s ratio at this moment. It is assumed that
greater Poisson’s ratio influences the speed oftransverse wave to become slower and efficiency to
be lower[3].
10

0.5

8

0.4

6

0.3
0.2

4

0.1

2
2

4

6

8

10

12

14

16

0

(a)
10

0.5

8

0.4

6

0.3
0.2

4

0.1

2
2

4

6

8

10

12

14

16

0

(b)
(a)

Fig. 3 μ-scan results of (a) aluminum and (b) steel
specimens.

(b)

5. Conclusions
From the result of scanning of each specimen,
we could determine distribution of Poisson’s ratio
in the specimen and concluded that Poisson’s ratio
is irrelevant to the thickness of the specimen. The
materials of relatively greater Poisson’s ratio wererather hard to obtain accurate Poisson’s ratio. In this
aspect the further research is required. We expectthat this system can be used to identify change ofcomposition in a specimen such as sintering in
ceramics and different material characteristics atwelded points.

(c)
Fig. 2 Typical pulse-echo signals from the steel
specimen (a) at 20 mm thick and (b) at 25 mm thick,and (c) aluminum specimen at 20 mm thick.
From the scanned results, Poisson’s ratios at eachpoint were calculated using equation (5). Although
the time intervals change with difference inthickness, Poisson’s ratio can be obtained
independently of specimen thickness. It isdemonstrated more obviously in Fig. 4, whichshows the distribution of Poisson’s ratio inaluminum and steel specimens. The similar color

Acknowledgment
This research was partially supported by the
Teacher-Student Research program of Korea
Science Academy in 2008.
References
1. H. F. Pollard: Sound Waves in Solids (Pion Ltd,
London, 1977) p.15, 25.
2. A. Kumar, T. Jayakumar, B. Raj and K. K. Ray:
Acta Materialia 51 (2003) 2417.
3. Y. Shin, Y. H. Yoon and Y. H. Kim: Journal of the
Korean Society for Nondestructive Testing 28(2008) 40.
4. Y. H. Kim, J. K. Lee and H. C. Kim: J. Korean
Phys. Soc. 42 (2003) 111.

2P2b-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 235- 236
11-13 November, 2008

Development of an ultrasonic face classification system
Zhenwei Miao, Wei Ji, Yong Xu, and Jun Yang† (National Laboratory of Acoustics, Institute of Acoustics,
Chinese Academy of Sciences)

1. Introduction
Face classification, as an active research area
over the last decade1-2), has its advantages of
non-intrusive and being well accepted by users. But
the variations of illumination, pose and facial
expression etc. always deteriorate the performanceof a face classification system. Although manyefforts have been put towards improving theclassification rate, the face classification in an
uncontrolled environment is still a challenging
problem. Recently, McKerrow et al.3-5) employed an
active ultrasound sensing technology to classify
human face by using a statistical classifier. The
classification results indicated that ultrasonicsensing was able to distinguish different faces.
The aim of our work is to develop a robust
ultrasonic sensing-based face classification system
free of the lighting conditions. Effective feature
extraction algorithms are proposed for improving
classification rate and verified by experimentresults. The rest of this paper is organized asfollows. Section 2 presents the basic theory. Section
3 describes the ultrasonic face classification system.
Section 4 designs the experiment and thenillustrates the test result of classification. Finally, abrief conclusion is made in Section 5.
2. Basic Theory
As the ultrasound encounters an object during
its propagation, according to the mechanism
described by Freedman’s ‘image pulse’ model6-7),
echoes are produced whenever the acoustic
impedance or any of the derivatives of it withrespect to range is discontinuous. The amplitude ofthe echo is inverse to the order of the derivatives
and proportional to the area of the discontinuity.
The discontinuities distribute over range, azimuthand elevation angle. When the ultrasonic beam
impinges on a face, echoes from these
discontinuities contain information of theirrespective areas, order of the derivatives and therelative range on the face as show in Fig.1.
The bottom area in Fig.1 shows the variationof the echo amplitude corresponding to the distance.
The ordinate represents the normalized amplitude
while the abscissa represents the distance with theunit of meter. The left bottom part of Fig.1
represents the orthogonal detection of a subject’s-----------------------------------------------------------jyang@mail.ioa.ac.cn

face. The first peak in the echo spectrum
corresponds to the nose, the second peakcorresponds to the forehead, the third to the lip, theforth to the cheeks, etc. The right-bottom part of
Fig.1 represents the sensing angled at 45° to thesame face. According to the alignment between theecho and the face features, our initial idea is that we
can classify the faces by using signal processing toanalyze the received echoes from them.

1
0.8
0.6
0.4
0.2

1
0.8
0.6
0.4
0.2

1.1

1.15

1.2

1.25

1.1

1.15

1.2

1.25

Fig.1. The face and the ultrasonic echo signal

3. Ultrasonic face classification system
Based on the above algorithm, we design theultrasonic face classification system. The block
diagram of this system is shown in Fig. 2.
SensComp’s Series 600 electrostatic transducer isused to transmit the chirp signal and G.R.A.S.
1/4” microphone is used to receive the echo. The
analog echo signals received by the microphone
were converted to digital signal by NI
DAQpad-6070E data acquisition card with a sample
rate of 500 kHz. Two transmitters are utilized in thissystem from multi-directions to detect human face.
Receivers of the same amount are employed tocollect echoes from different angles.
R

DemodulateT

Chirp signal

Data Process

Classification

Fig. 2 Block diagram of the face classification system

Fig. 3 illustrates the experiment setup. One
transmitter and one receiver combine a TR-pair.
Two TR-pairs, named TR-A and TR-B, are fixed on
a spherical frame. They aimed at the front of theface orthogonally and 45°, respectively. One
reference point was set 1 meter away from the two
TR-pairs to position the subject’s faces. One camera
was used to record the subject’s facial expression
and track slight movement of the head so that we
can analyze the echo spectrums accordingly.

then compared the classification rate in Table 1.
Table 1. Results of the face classification experimentFeatureextraction
methodMethod I

Method II

Method III

Fig. 3 Experiment setup

4. Experiment design and classification
The experiment was carried out with agroup of samples including 10 persons (4 females
and 6 males). In order to acquire reliable echo data,
the subjects were required to cooperate with the test
as follows:
1) Keeping head not tilted, looking straightforward, nose tip closely sticking to thereference point;2) Allowance of head movement such as slightly
turn left or right within a small angle range ofabout 5°;3) Taking off glasses, earrings, and any otherhead accessories.
Three methods were used in feature
extraction in our work. The first extraction method3)
was McKerrow’s method (Method I) in . The
second extraction method (Method II) was
simplified from McKerrow’s method bydecreasing the number of thresholds from nine tosix with adjustment of threshold values.
Furthermore, we proposed a new feature
extraction method (Method III). The facial features
were picked from the power spectrum of thedemodulated echo signal directly.
The features were evaluated by both the
8)classical KNN and Bayes classifiers , respectively.
For each subject and each detection angle, there
were 100 data samples, 67 samples were used astraining samples, and the rest were used as testing
samples. We set k = 1 in the KNN classifier andData source

KNN
classifier

Bayes
classifier

TR-A
TR-B
TR-A&TR-B
TR-A
TR-B
TR-A&TR-B
TR-A
TR-B
TR-A&TR-B

73.3%
89.4%
97.9%
77.9%
91.5%
98.8%
98.5%
97.6%
100%

67.0%
82.4%
95.8%
71.8%
87.9%
97.9%
97.3%
93.3%
99.1%

From Table 1 we can see that, using the sameclassifier, the features extracted by Method III cangive a better classification result than that by theother two methods in the same experimental
condition. Features extracted from echoes collectedby TR-B leaded to a higher classification rate thanthat by TR-A did if they were extracted by Methods
I or II, but it was not the case when they wereextracted by Method III. Nevertheless, no matter
which method was chosen to extract features, data
fusion gave the best results.
5. Conclusion
A robust ultrasonic sensing-based faceclassification system free of the lighting conditions
is presented in the paper. With effective feature
extraction algorithms and proper configurations of
TR-pairs designed in this work, the proposedsystem could achieve a high classification rate in
the lab condition.
Acknowledgment
This research was partially supported by the
National Natural Science Foundations of China
under Grant No. 60535030.
References
1. R. Chellapa, C. L. Wilson, and S. Srrohey: Proc.
of the IEEE, 83 (1995) 704
2. S. Z. Li and A. K. Jain: Handbook of Face
Recognition. (Springer, Ger., 2005)
3. K. K. Yong and P. J. McKerrow: Proc of Aus.
Conf. on Robotics & Automation (2005)
4. P. J. McKerrow and K. K. Yoong: Proc. Towards
Autonomous Robotic Systems (2006) 111
5. P. J. McKerrow and K.K. Yoong: Robotics andAutonomous Systems, 55 (2007) 702.
6. A. Freedman: Acustica, 12 (1962) 10.
7. R. Kuc: J. Acoust. Soc. Am. 102 (1997) 689
8. R. O. Duda, P. E. Hart, and D. G. Stork: Pattern
Classification. (Wiley, Am, 2000). p 174

2P2c-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 237- 238
11-13 November, 2008

Development of a Movable Inspection Sensor for a Pipe
Using an EMAT
電磁超音波探触子を用いた移動型配管探傷センサの開発
Yusuke Okawa 1†, Riichi Murayama 1, Hideaki Morooka 1, and Yusuke Yamashita 1(1 Facult. Eng.,Fukuoka Institute of Technology.)
大川悠助1‡，村山理一1，諸岡秀昭1, 山下雄介1

1. Introduction
In recent years, a nondestructive inspection
technique using a pipe wave, a type of ultrasonicwave that can travel a long-distance along a pipe
was applied as a nondestructive inspection method.
We have tried to develop a pipe wave sensor which
is movable and can be easily installed using an
Electromagnetic Acoustic Transducer (EMAT).

（1福岡工業大However, we cannot confirm a T-mode pipe wave
using this sensor. Therefore, we developed the
EMAT composed of an electromagnet, which cangenerate a static magnetic field along thecircumferential direction, and a circle-shaped
sensor coil, which can generate a dynamic magnetic
field along the axis direction of a pipe.
Electromagnet

N

2. Characterization of a pipe wave
Figure 1 shows the theoretical dispersion curve of
the group velocities of a pipe wave for a steel pipewith a 43 [mm] diameter and 1 [mm] thickness. We
can confirm that there are a T(0,1) mode and T(1,1)
mode which vibrate in the circumferential directionof a pipe [2] and travel along the axial direction of apipe, an L(0,1) mode and L(0,2) mode which
vibrate and travel along the axial direction of a
pipe.
6000

Group velocity (m/s)

5000
4000
3000
T (0,1)2000

T (1,1)

1000工）

Electromagnet

S

N

S

Static magnetic field
Dynamic magnetic field
Ultrasonic wave
Displacement direction

Sensor coil

Sensor coil

A.L-mode type
B.T-mode typeFig.2 Drive principle of an EMAT for a pipe wave

4. Basic structure of the trial EMAT
The displacement distribution of the circumferential
direction of the T (0, 1) mode and T (1, 1) modes
are shown in Fig.3. It suggests that a uniform static
magnetic field along the circumferential direction isnecessary to generate a T (0, 1) mode pipe wave.
Therefore, we manufactured many electromagnets
which could supply a uniform magnetic field in thecircumferential direction as shown in Fig.4.

L (0,1)
L (0,2)

0
0

50

100

150
200
Frequency (kHz)

250

300

Fig.1 Group velocity dispersion curves

3. Drive principle of an EMAT for a pipe wave
The drive principle of an EMAT generating an
L-mode pipe wave is shown in Fig.2 (A). The
EMAT composed of an electromagnet which cangenerate a static magnetic field along the axis
direction of a pipe and a circular-shaped sensor coilwhich can generate a dynamic magnetic field along
the axis direction of a pipe. We next devised a trial
EMAT for a T-mode pipe wave as shown in Fig.2(B). The EMAT is composed of an electromagnet
which can generate a static magnetic field along theaxis direction of a pipe and a sensor coil which cangenerate a dynamic magnetic field along thecircumferential direction of a pipe.
-----------------------------------------------------------E-mail:mcm07002@bene.fit.ac.jp

A. T (0, 1) mode
B. T (1, 1) mode
Fig.3 Cross-sectional illustrations of circumferential
vibration modes
Electromagnet

Pipe

N

Pipe wallN

Sensor coil

S
S

N

S

Static magnetic field
Dynamic magnetic field
Ultrasonic wave
Displacement direction

Fig.4 Drive principle of an EMAT for a T-mode pipewave

5. Experimental system
The experimental system is shown in Fig.5. Steelpipes (STKM) of 43 [mm] outside diameter, 2400
[mm] length and 1 [mm] and 2 [mm] pipe wall
thicknesses were used as the test specimen.

are 4%, 8%, and 15%, respectively. The samples ofthe signal waveform are shown in Fig.9. We could
confirm the reflection signal from the 15% circular
defect.
sensor

Simulated defect point
A. Defect echo

Broadband amplifier
RI EC

FREQUENCY

HIGH POWER PULSER

1 2 3

B. Pipe-end echo

WAVE

0

4

Oscilloscope

PULSE
FINE

0.4
Amplitude （V）

Preamplifier

Matching circuit
Electromagnet

Ultrasonic wave

DC power supply

Signal amplitude [V]6. Experimental results
6-1. Optimization of the static magnetic fieldstrength
The static magnetic field strength is then adjusted
to become the maximum received ultrasonic signal.
Fig.6 shows the relationship between the magnetic
field strength and the received ultrasonic wave
signal strength. As can be seen, the highest signal
was obtained at the magnetic field of 70 [mT].
0.8
0.6
Experimental condition

0.2

0

20
40
60
Magnetic flux density [mT]80

Fig.6 Relationship between the signal amplitude and themagnetic flux density

100
50
0
200

300

-100

Angle [degree]

Fig.7 Relationship between themagnetic flux density and thecircumferential angle

Group velocity [m/s]

6-2. Confirmation of the pipe wave mode
The static magnetic field distribution in thecircumferential direction of a pipe is shown in Fig.7
and the velocity distribution curve due to the drive
frequency that ranges from 60 [kHz] to 160 [kHz] isshown in Fig.8. As can be seen, we could notobserve the T (1, 1) mode.
Magnetic flux
density [mT]

1000

0
-0.2

0

500

1000

-0.4
Time (μs)

6-4. Scanning inspection results
We scanned the trial EMAT in the axis direction of
a 500 [mm] pipe. Figure 10 shows the attenuation
rates of the reflection signal from a circular holedefect and a slit defect. It was confirmed that theattenuation rate of the reflection echo of a circularhole defect is obviously enlarged when compared tothat of a slit defect.
50

Wall thickness 1[mm]Wall thickness 2[mm]

40
30
20

Defect of slit

10
0
4%

0

100

500

A. Non-defect signal
B. Defect signal (15%)
Fig.9 Example of received ultrasonic waveforms

Fig.5 Experimental system

0

0

0.2

Time (μs)

Receiver coil

0.4

0

-0.4

Steal pipe
Transmitter coil

0.2

-0.2

B

0.4

Attenuation rate [%/m]Burst pulsar

-50

A

B

POWER

Amplitude （V）

VDD

8%
15%
Cross sectional defect rate

Fig.10 Relationship between the cross-sectional defect rate andattenuation rate

7. Conclusion
We developed a trial EMAT for a T-mode pipe
waves and could observe a defect echo by certain
kinds of defects. We also showed that the potential
to distinguish the type, size and depth of the defect.
Both the L and T-mode pipe waves will be
combined by an L-mode EMAT and a T-mode
EMAT in the future.

3500
3000
Wall thicness 1 [mm]Wall thicness 2 [mm]Theoretical figure

2500
2000
60

80

100
120
Frequency [kHz]140

Fig.8 Relationship between
the group velocity andthe drive frequency

6-3. Inspection results
Three kinds of circular through holes (diametersof 5, 10, and 15 [mm]) were machined into the pipe.
The cross section area rates of these circular holes

Acknowledgements
This work was partially supported by aGrant-In-Aid for Scientific Research (C19560104).
We acknowledge Dr. T.Hayashi at the Nagoya
Institute of Technology for offering the software tocompute the pipe wave velocity dispersion curves.
References
1. H.Nishino et al., Jpn. J. Appl. Phys. Vol. 40,
pp364-370, 2001.
2. H.Kwun et al., Mater. Eval. Vol.62, pp 430-433,
2004.

2P2c-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 239- 240
11-13 November, 2008

Development of Circumferential Scan in Pipes by Non Contact
Air Coupled Ultrasonic Testing
非接触空中超音波によるパイプ円周方向探傷の開発
Masakazu Takahashi1, Hidekazu hoshino1, Yukio Ogura1, Hideaki Kitagawa2, Junichi
Kusumoto2, Akihiro Kanaya2, Hideo Nishino3 ( 1Japan Probe Co. Ltd; 2Kyushu ElectricPower Co., Inc. 3Inst. Tech. & Sci., The Univ. of Tokushima )高橋雅和 1，星野秀和 1，小倉幸夫 1，北川秀昭 2，楠元淳一 2，金谷章宏 2，西野 秀郎 3（ 1 ジャ
パンプローブ㈱, 2 九州電力㈱, 3 徳島大院 ）1. Introduction
A guided wave propagating along
circumferential direction of a pipe ( circumferential
guided wave; CGW ) has been anticipated for a
rapid and efficient screening technique for themonitoring of piping. The CGW is classified into
two propagation modes, namely, the circumferential(C-) SH and the C-Lamb waves. Several reports ofthe propagation phenomena [1–5] and applications
for NDT [6, 7] of the CGW have been published.
On the other hand, air coupled transductionsof ultrasounds in solid materials have also been
expected to apply to any kind of environments andfor on-line monitoring because of their
non-contacting feature. In this paper, we propose anovel method of defect detections by non contact
air coupled ultrasonic testing ( here after called
NAUT ) in pipes using the C-Lamb waves
generated and detected by a pair of air-coupledprobes. A specially designed focusing probe for
efficient transductions was also described.
Experimental verifications of both defect detectionsof the method and the special probe were shown.
2. Experimental setup
Several 10 cycles of negative rectangularmonopole burst pulses generated by the high power
tone-burst pulsar / receiver ( Japan Probe JPR –QD ) were employed in the experiments. The pulsar/ receiver built-in the 60 dB amplifier has been
designed for the NAUT with optimum electronics.
Piezoelectric 1-3 composite probes ( PCP’s ) wereused for the NAUT. Center frequencies of PCP’s
are 400 kHz ( 0.4K14x20N and 0.4K40x20N –R190 ) and 800 kHz ( 0.8K14x20N ), respectively.
The element size is 14x20 mm in a case of
0.4K14x20N, K is the composite material. The
suitable matching layers are utilized for the efficienttransductions. The test pipe is φ 318.5 mm outer
diameter with 14.3 mm thick steel pipe. Incident
angle to the pipe surface of the radiated longitudinal
waves was set to be optimum value [8, 9, 10] togenerate the C-Lamb waves efficiently.
------------------------------------------------------------e-mail address : masakazu-takahashi@jp-probe.com

3. Constant incident angle method by focusing
probe
Incident angle of a plane wave ( normallygenerated by a flat vibrator ) to a surface of a pipe
varies accordingly to the irradiation position asshown in Fig. 1 (a). This phenomenon is ineffective
for the C-Lamb wave generations. Therefore, wehave developed the constant incident beam angle( CIBA ) method by using a focusing probe as
shown in Fig. 1 (b). In this setting, when the
angular aperture θ takes small, the incident angle iapproximately takes constant value. Fig. 2 shows(a) Plane probe(b) Focusing probe
Fig. 1 Oblique incidence to pipes. by NAUT
0.5 round

1.5 round

2.5 round(a) Plane probe ( Gain : 38.7 dB )0.5 round

1.5 round

2.5 round(b) Focusing probe ( Gain : 28.5 dB )Fig. 2 Example of transmission waves

time domain signals obtained by the plane probe (a)and the CIBA method (b). It was obviously
confirmed that the obtained amplitude and signal tonoise ratio by the CIBA method was improved ( 10dB gain up ).

Probe holder

4. Development of tandem method
Conventional transmission method which
two probes being faced each other doesn’t identify
defect position, however the new developed method
enables to determine the defect position. Fig. 3
shows the tandem method using a pair of
air-coupled probes and the echo pattern.

(a) Side view of experimental arrangement

Receiving probe②Receiving probe
defect echo
①Transmitting
probe

criterion echo

Transmitting probe
Defect(b) Closed up view of the probe holder
A

Fig. 3 The tandem method and the echo pattern

The transmitting probe ① sends ultrasonicbeam to the pipe and the receiving probe ②
receives a little diffraction echo from propagatedcircumferential guided wave in the pipe, the echo issmall, and position is constant in time. Therefore
we call it “criterion echo” which is important todetermine defect position by the distance between
criterion echo and the defect echo. Fig. 3 shows thecriterion echo and the defect echo in the distance A= 320 mm between defect and probe. Fig. 4 showsthe experimental arrangement of the equipment inthis method. Fig. 5 shows some examples ofdetecting defect echoes, to enable to find φ 4 mm ×
4 mm deep flat bottom hole.
5. Conclusion
High power square tone burst, pulsar/
receiver can make possible to generate the highguided wave into pipe and to receive effectively itin the NAUT. We have developed the effective
generating and propagating guided waves in
optimum frequency, incident angle and probe.
Improvement of signal noise ratio and highsensitivity has been obtained by the NAUT. The
tandem method evaluates the defect position fromthe distance between the criterion echo and thedefect echo, to find the defect size of 3 mm deep
slit and φ 4 mm × 4 mm deep flat bottom hole.

Fig. 4 Experimental arrangement of the tandem method
φ 4 mm × 4 mm
criterion echo

Fig. 5 Example of detecting φ 4 mm × 4 mm deep flatbottom hole

References[1] G. Liu and J. Qu: J. Appl. Mech. 65 (1998) 424[2] X. Zhao and J. L. Rose: JASA 115 (2004) 1912
[3] H. Nishino and K. Yoshida: Acoust. Sci. Tech.
27 (2006) 389[4] H. Nishino, R. Yokoyama, H. Kondo and K.
Yoshida: JJAP 46 (2007) 4586
[5] H. Nishino, R. Yokoyama, K. Ogura, H. Kondo
and K. Yoshida: JJAP 47 (2008) 3885
[6] M. Hirao and H. Ogi: NDT&E 32 (1999) 127[7] W. Luo et al: AIP conf. Proc. 820 (2006) 165[8] H. Nishino et al: Proc. JSNDI fall meeting(2007) p.27 [in Japanese][9] M. Takahashi et al: Proc. JSNDI spring meeting(2008) p.5 [in Japanese][10] H. Reissner: Helv. Phys. Acta 7 (1934) 140 [inGerman]2P2c-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 241- 242
11-13 November, 2008

Nonlinear Acoustic Evaluation of Creep Damage in a Cr-Mo-V
Steel
非線形超音波法を用いた Cr-Mo-V 鋼のクリープ損傷評価
Toshihiro Ohtani † (Faclut. Eng., Shonan Inst. Tech.)
大谷俊博†(湘南工大 工)

1. Introduction
Many of fossil power plants, which wereconstructed during 1960's and 70's and exceed morethan 100,000 working hours, have presently been
operating while they have underwent progressive
damage, mainly from creep, as the time proceeds1).
Furthermore, by shifting the base load of powerfrom fossil power plants to nuclear power plants,
they are faced to even more severe operating
condition such as daily or weekly startup andshut-down in order to correspond to rapid change ofthe de-mand. As the consequence of this trend, thematerial's degradation is being accelerated.
Therefore, a non-destructive technique is now
highly required for safely operating plants andpredicting the remaining life. It is also important for
the technique to be simple and quick oper-ating tocope with the large number of measuring points.2)

In this study, we apply an electromagnetic
acoustic transducer (EMAT) to monitor thesurface-shear-wave nonlinearity throughout
creep life of metals. The use of an EMAT
makes contactless transduction possible.
However, EMATs lack a large transduction
efficiency, which the nonlinear measurement
needs. To overcome this limitation, we chose touse electromagnetic acoustic resonance(EMAR) 2) so as to excite and enhance thestanding wave of the second-harmoniccomponent around a cylindrical specimen.
Coherent superposition produces highly
magnified amplitude of the second harmonics.
The measured surface-wave nonlinearity
detected the peak around 20 % of creep life.
2.

Samples and experimental condition

We performed creep tests using specimens
φ14 mm in gauge diameter, 60 mm in gauge length3). The material of the specimens was commerciallyavailable JIS-SNB16. The heat treatment chemicalcomposition and mechanical properties at room
temperature are found in Ref. 3 The creep tests------------------------------------------------------------†

E-mail: ohtani @mech.shonan-it.ac.jp

were performed at 923 K in the atmosphere byusing a vertical single-lever creep machine and aheating electric furnace. Twelve creep specimens
are prepared for 25 MPa. The creep test
individually carried out until the creep strainreached target value. After the creep tests, thenonlinear ultrasonic characteristics were measured
at room temperature.
Meander-line coil (dynamic field)
Solenoidal coil (static field)
Specimen

Tone burst
SH-wave

Signals

Current
Hω
Hω

H0
Ht
Ht

H0
Meander-line coil

Shear
deformation
H0

Meander-line coilSH-wave

Fig. 1
Configuration and mechanism of themagnetostrictive EMAT for generating and receiving
the axial shear wave.

3.

EMAR for nonlinear acoustics

Figure 1 shows the magnetostrictively
coupled EMAT designed for the axial shear wave inferromagnetic materials.
It consists of asolenoidal coil to supply the biasing magnetic fieldalong the axial direction and a meander-line coilsurrounding the cylindrical surface to induce thedynamic field in the circumferential direction.
The total field oscillates in the axial direction at thesame frequency as the driving currents andproduces a shearing vibration through themagnetostriction
effect,resultingintheaxial-shear-wave excitation. The same coil works
as receiver through the reverse mechanism2).
Driving the meander-line coil with long tone
bursts causes interference among the axial shear
waves traveling around the cylindrical surface, anda frequency scan detects resonance peaks at unequalAmplitude [a.u.]

1.0

0.004

0.8

A2

0.6

0.002

0.4
0.2
0.0
3.84

3.85

3.86

3.87

3.88

0.000
3.89

Frequency [MHz]Fig. 2 Resonant spectra for the fundamental and thesecond-harmonic components.

4.

Results

Figure 3 shows the relationship between the
nonlinearity A2/A1, relative velocity, ΔV/V0 (V0:initial velocity), the creep strain, the strain rate, andestimated life fraction t/tr (the creep time/ estimatedcreep life). For the estimation of t/tr of each sample,
we applied the modified θ projection and therupture parameter 5, 6). A2/A1 reached its peak at t/tr
= 0.2, and it dropped to the minimum level at t/tr =0.5. The creep strain rate decreased from the start ofcreep until t/tr = 0.2, remained steady until t/tr = 0.5,
and then gradually increased before the rupture.
These changes correspond to three creep regimes:
transient creep, steady creep, and accelerating creep.
These results were the same as the change ofattenuation coefficient obtained by the bulk
shear-wave EMAT 3), possibly suggesting that the

-1

30

-5

10

20
:Strain:Strain rate

10
0

-3

10

923 K, 25 MPa

10Strain rate [s ]

40

-4

(b)

:A2/A1

(a)

-6

10

1.0

:ΔV/V0

0.5
5
0.0
0
0.0

0.2

0.4

0.6

0.8

ΔV/V0 [%]

Strain [%]

50

-0.5
1.0

Life fraction, t/tr

Fig. 3 Relationship between A2/A1, ΔV/V0, the creep
strain, the strain rate, and life fraction, t/tr.

5.

0.006

A1

Amplitude [a.u.]

1.2change in A2/A1, as shown in Fig. 3, was due toabsorption by dislocation vibrations7). Furthermore,
we observed the change of dislocation structureswith TEM. The evolution of A2/A1 as creep progress
is related to the microstructure change, especially,
dislocation structure.

A2/A1 [x10 ]

frequency intervals, at which all the waves overlap
coherently to produce lareg amplitudes.We used thefirst resonant mode around fr=3.9MHz, whoes
amplitude distribution has the miaximu at thesurface and a steep gradient with the radius; thepenetration depth is estimated to be 0.5 mm 4). We
defined the maximum amplitude of the firstresonance peak as the fundamental amplitude, A1(Fig. 2). We then excited the axial shear wave by
driving the EMAT at half of resonant frequency(fr/2), keeping the input power unchanged. In thiscase, the drivng frequency does not satisfty theresonant condition and the fundamental componet
does not produce a detactable signal. However, thesocond harmonic component having double
frequency (fr) satisfies the resoonat condition andthe resonance spectrum of the received signal
contains a peak at the original resonant frequency
as shown in Fig.2. We defind this peak height assocond-harmonic amplitude, A2, to calculated thenonlinearity A2/A1. These measuremnt were madepossible by the system for nonlinear acoustic
phenomena (SNAP) manufactured by RITEC Inc...

Conclusion

Creepdamagein
Cr-Mo-V
steel(JIS-SNB16) at 923 K in air was evaluated throughthe nonlinearity A2/A1 measured with the EMAR
method. The A2/A1 showed a peak at around 20%
and a minimum value at 50 % of the creep life,
which is interpreted as resulting frommicrostructural changes, especially, dislocation
mobility.
References
1. R. Viswanathan: Damage Mechanism and Life
assessment of High Temperature Component(ASM International, Metals Park, OH, 1989)
p.1.
2. M. Hirao and H. Ogi: EMATs for Science andIndustry (Kluwer Academic, Boston, 2003) p. 1.
3. T. Ohtani, H. Ogi, and M. Hirao: Jpn. J. Appl.
Phys. 45 (2006) 4526.
4. H. Ogi, T. Hamaguchi and H. Hirao: Metall.
Mater. Trans. A 31A (2000) 1121.
5. K. Maruyama, C. Harada and H. Oikawa: J.Soc.
Mater. Sci. Japan. 34 (1985) 1289.
6. K. Maruyama, H. Oikawa: Trans. ASME, J.
Pressure Vessel Techno. 109 (1989) 142.
7. A. Granato and K. Lücke: J. Appl. Phys. 27(1956) 583.

2P2c-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 243- 244
11-13 November, 2008

Nonlinear ultrasonic characterization of thermallydamaged Westerly granite
Claude Inserra‡, Shiro Biwa and Youqing Chen (Graduate School of Energy Science,
Kyoto University)

1. Introduction
The influence of temperature on themechanical properties of rocks is of relevant
importance in geophysical applications, that require
heating and cooling of rocks. While the temperature
variation imposed to rocks will generate an internal
thermal stress large enough to create cracks, thelocal variation in the temperature gradient willcause the propagation of existing cracks. These two
mechanisms lead to the deterioration of the material,
and the thermal cracking affects the elastic
properties of rocks. As a consequence, in addition
to optical measurements of the internal
microstructure of rocks1), nondestructive ultrasonicmethods are of great interest for the characterizationof the evolution of elastic properties of rocks underthermal treatment. Usually, P and S-wave velocities
are measured to follow the deterioration of material,and by means of the effective medium theory2,3), theaverage characteristics of defects (crack density,
crack mean aspect ratio) can be evaluated. Thesemethods assume that cracks are open, randomly
distributed and that a linear macroscopic
stress-strain relationship of the solid matrix holds.
However, several experimental studies haverevealed a nonlinear elastic behavior of rocks
indicating that the nonlinear acoustic methods arehighly sensitive to the defects (cracks, intergrain
contacts) than linear ones. In this study, thermallydamaged Westerly granite samples are probed bylinear and nonlinear ultrasonic methods. First,
linear ultrasonic methods are used to follow the
P-wave velocity variation during thermal damage.
Then, a nonlinear acoustic phenomenon is observed
and the results discussed.
2. Experimental setup and procedure
The experimetal setup is presented in Fig.1.
Circular cylindrical samples of Westerly granite, oflength 40 mm and diameter 20 mm, are probed byultrasonic waves. A pulse or toneburst wave wassent to the rock cylinder, using a high-power pulse
emitter (RITEC RPR-4000) to excite a piezoelectrictransducer (Panametrics) with a 1 MHz nominal
frequency. The transmitted wave was then detected
at the end of the rod by a wideband transducer with-----------------------------------------------------------claude.inserra@at7.ecs.kyoto-u.ac.jp

Transmitter (1 MHz)

Pulse emitter
RITEC RPR4000

Rock cylinder
Digital Oscilloscope

Receiver (2.25 MHz)

Waveform
StoredPC

Fig. 1

Schema of the experimental setup.

a 2.25 MHz nomimal frequency. Silicon oil
couplant was used between transducers and rocksamples. In experiments using toneburst, the time
length of the signal was 10 µs (10 periods). The
emitted and transmitted waveforms were stored via
a digital oscilloscope (Tektronix TDS340AP). In
order to observe nonlinear effects, the excitation
voltage was varied at 19 steps linearly spaced
between 110 V and 450 V.
To investigate the effects of cracks occuringinside Westerly granite when heating, five samples
were subjected to a one-cycle heating and coolingtest under different holding temperatures. Prior to
the ultrasonic measurements, the effective porosity
was measured for all the samples by a water
evaporation method, which required drying them to
100 °C. So, the samples were all heated above thecrack-initiation temperature in the granite,established around 60 °C with acoustic-emission
monitoring4). However, the damage occuring inthese samples due to this process can be considered
as low, and the samples after the porosity
measurement are called intact samples. The heating
and cooling rate were chosen constant, at 50 °C/hr,
and the holding temperature was varied as 200, 300,
400 and 500 °C, with holding time of 30 minutes,
for four samples, while keeping one as a reference
sample without thermal damage.
3.

Results
First, wide band pulses were used to measurethe P-wave velocity of the samples, by means oftime-of-flight measurement based on zero-crossing
method. The P-wave velocity of 4060 m/s,
measured in the intact sample, decreased to 2195
m/s for the sample heated at 500 °C, exhibiting alinear decrease of velocity with the holding
temperature. These results show a nearly 50%
decrease in the P-wave velocity, confirming thatlinear ultrasonic measurements are a good indicatorof the deterioration of the samples. However, it iswell known that nonlinear ultrasonic measurements
are more sensitive to the presence of defects inmaterials, like cracks or intergrain contacts. So, inorder to check acoustical nonlinear properties of themedium, tonebursts, instead of pulses, were emitted
at increasing excitation amplitude. The transmitted
waveforms at high excitation amplitude (450 V) for
the intact sample and the 500 °C damaged one areshown in Fig.2. For the intact sample, the shape ofthe emitted toneburst is conserved, with slight
distorsion. The Fourier spectrum of this signal
showed one peak at 1 MHz and no harmonic
generation, due to the high attenuation of ultrasonicwaves in granite. After heating at 500 °C, thetransmitted waveforms contain essentially nofrequency components around 1 MHz. The Fouriertransform revealed that all the energy of the signal
has been transferred to lower frequency
components. The waveform appeared to be the time
derivative of the envelope of the emitted toneburst,
explaining the change in phase of transient peaks(the first and last ones). This nonlinear effect, called“self-demodulation” process, has already been
observed in sand5), and is well known in fluid
mechanics6). For samples heated below 500 °C, thetransmitted waveform are intermediate states
between the ones presented in Fig.2, and contain

Voltage (V)

4

(a)

2
0

-4
0

Voltage (V)1020Time (µsec)

30

40

10

20
Time (µsec)

30

40

(b)

0

-0.5
0

4. Discussion

While the acoustical linear properties are
sensitive to the average elastic properties of an
inhomogeneous material, nonlinear acoustic
methods are highly sensitive to their defects. When
heating Westerly granite up to 500 °C, crack appear
progressively causing high damage of granite. The
nonlinear acoustic method in terms of theintroduced damage factor shows higher sensitivity
to damage than linear velocity measurements. The
self-demodulation process finds its origin in theparametric array theory. It is then possible todescribe it by adding a nonlinear quadratic
parameter in the stres-strain relationship of themedium. The evolution of the damage factor withincreasing amplitude, giving new information aboutacoustical nonlinearities of rocks, is currently
studied in order to extract such nonlinear quadratic
parameter and its evolution with thermal damage of
granite.
Acknowledgment
This work was supported by the JSPS
Postdoctoral Fellowship.

-2

0.5

both the transient peaks corresponding to
self-demodulation process, and the high frequency
component attenuated due to damage of materials.
By increasing the excitation voltage, slightdifferences appear between the level of the transient
peak amplitudes (corresponding to the nonlinear
self-demodulation process) and the intermediatehigh-frequency amplitude (subjected to the linear
attenuation). This effect, due to increasing acoustic
wave amplitude, is an indicator of the acousticalnonlinearity of the material. To extract such
nonlinear information, a damage factor has been
defined as the ratio of the mean amplitude of thehigh frequency components to the maximum of thetransient peak amplitudes. This damage factor,
scaled between 0 (highly damaged rock) and 1(intact rock), decreases below 10% of the initialvalue, at the lowest excitation voltage, for the
maximum holding temperature studied.

Fig. 2 Evolution of the transmitted toneburst for the
intact sample (a) and the thermally damaged one (b).

References
1. Y. Chen, T. Kobayashi, Y. Kuriki, H. Kusuda and
M. Mabuchi：J. Jpn. Soc. Eng. Geol., in press.
2. T. Reuschle, S.G. Haore and M. Darot：Earth.
Plan. Sci. Lett. 243 (2006) 692.
3. M.H.B. Nasseri, A. Schubnel and R.P. Young：Int. J. Rock Mech. Min. Sci. 44 (2007) 601.
4. C. Yong and C. Wang：Geophys. Res. Lett. 7(1980) 1089.
5. V.Yu. Zaitsev, A.B. Kolpakov and V.E. Nazarov：
Acoust. Phys. 45 (1999) 202.
6. M.A. Averkiou, Y. Lee and M.F. Hamilton：J.
Acoust. Soc. Am. 94 (1993) 2876.

2P2c-10

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 245- 246
11-13 November, 2008

Optimal Time Reversal Focusing of Random Array
Using an Iterative Least Squares Pre-filtering Method
Dengyong Ma and Jun Yang† (National Laboratory of Acoustics, Institute of Acoustics,
Chinese Academy of Sciences)

2. the Proposed ILS-PF method
The nonreciprocal time reversal (NR-TR)
model was presented by Roux et al. 4) Using thismodel, the TR focusing of random array can berealized. Due to propagation information losses, the-----------------------------------------------------------jyang@mail.ioa.ac.cn

T ra n s m itte d S o u rce S ig n a l W a v efo rm

J-source array

1
0.7 5

Single Receiver#

Normalized Signal Amplititude

The time reversal mirror (TRM) has been
widely used to focus ultrasound beams for thedetection of defects in solids, ultrasonic medical
imaging and therapy1). Generally, TRM methods
employ uniform linear arrays to achieve thespatiotemporal focusing at a predefined position.
The demands of even spacing and frequency
response uniformity for the linear array lead tolaborious array calibration in practical applications.
On the other hand, in real environments, due to the
propagation information losses, classical TRM does
not behave as an inverse filter, which makes thetime reversal (TR) focusing signal different
obviously from the source signal. In order to obtainan optimal TR focusing, Tanter et al.2) designed aspatiotemporal inverse filter derived from thereciprocal of a diagonal transfer matrix. Montaldo
et al.3) presented an iterative TRM method
implemented by using the focusing error signal tocorrect TR signal iteratively. However, repetitioustransmit-receive operations make these methods
laborious and time-consuming for real applications.
To overcome the disadvantages of traditional
TRM method, we propose an iterative least squares
pre-filtering (ILS-PF) method for an optimal TR
focusing. Meanwhile, a random array is employed
to solve the restriction of the linear array. In thispaper, the multiple pre-filters’ coefficients arecalculated using a least squares criterion, and thenthe TR signal is pre-filtered successively andreemitted again to achieve inverse filter focusing.
Compared with the previous TRM methods, thepresented method is simple and fast to implement.
Moreover, the use of a random array permits
placing transducers liberally according to real needin practice, and retrains from the array response
calibration. The optimal focusing of four-element
random array is conducted in a reverberationchamber. Experimental results demonstrate theeffectiveness of the presented method.

autocorrelation of time domain Green’s function is
not ideal Dirac delta function and the NR-TR
focusing signal can not be recovered to the source
signal as shown in the Fig.1. For an optimal TR
focusing, a least squares pre-filter (LS-PF) isinserted into the emitter end to compensate theautocorrelation of Green’s function so that an ideal
Dirac delta function can be achieved. The signal
flow graph of LS-PF method is shown in Fig.2.
0 .5
0.2 5
0
-0.2 5-0 .5-0.7 5-1Time Reversal0

0.0 050.0 1
0 .01 5
0 .02
T im e Ax is ( S ec o n d )0.0 250.0 3

R ec eiv ed F o c u sin g S ig n a l W a ve fo rm U s in g N R -T R m e th o d
1
0.7 5

#

Single Receiver

Normalized Signal Amplititude

1. Introduction

0 .5
0.2 5
0
-0.2 5-0 .5-0.7 5-1J-source array0

0.0 050.0 1
0 .01 5
0 .02
T im e Axis ( s ec o n d )0.0 25

0.0 3

Fig.1 Received focusing signal waveform of fourelement random array using NR-TR method
Received Signal

Green’s Function

Source Signal

TR Signal

Green’s Function

TR Focusing Signal

Pre-filter

LS Estimator

Green’s Function

Optimal Focusing Signal

Fig.2 Signal flow graph of LS-PF method

The source signal of J-element array can be
expressed in time domain by
G
S = [1 1 " 1]1×J ⊗ [s(0) s(1) " s(N − 1)]T = 11×J ⊗ s , (1)where “ ⊗ ” represents the Kronecker operator. The
impulse response of Green’s function between i-tharray element and receiver is defined as
g i = [gi (0 ) gi (1) " gi (L − 1)]T ,(2)
and the received signal is denoted as
r1 = [r1 (0 ) r1 (1) " r1 (N − 1)]T =

J

∑G

G

R, ps

.

(3)

p =1

where G R , p is an N × N transfer matrix and given by⎧⎪ g p [(L − 1) − ( j − i )],0 ≤ j − i ≤ L − 1
G R , p (i , j ) = ⎨.
⎪⎩ 0 ,other(4)

The TR signal is written asG
r1, TR = [r1 (N − 1) r1 (N − 2 ) " r1 (0 )]T =

J

∑G
p =1

G

L , p s , (5)⎧⎪g [(L −1) − (i + j − N −1)], 0 ≤ i + j − N −1 ≤ L −1
GL, p (i, j ) = ⎨ p
. (6)
⎪⎩0,
other

The TR focusing signal is denoted as
r2 = [r2 (0 ) r2 (1) " r2 (N − 1)]T =

J

∑

J

G R ,q

q =1∑ G s . (7)
L, p

G

p =1

The impluse response of pre-filter is defined as
w = [w(0 ) w(1) " w(M − 1)]T .
(8)
The filtered TR signal is written as
r1,TRF = [r1,TRF(N − 1) r1,TRF(N − 2) " r1,TRF(0)]T
J
, (9)
G
= WF

∑G s
L, p

p =1

where WF is an N × N filter response matrix given by⎧⎪w[(M −1) − ( j − i )], 0 ≤ j − i ≤ M −1
WF (i, j ) = ⎨
.
⎪⎩0,
other

The optimal

focusing signal for the filtered TR signal is
r2,opt = [r2,opt (0 ) r2,opt (1) " r2,opt (N − 1)]T
J

=

∑

J

G R , q WF

q =1

(10)

∑G s = W r
L, p

G

F 2

p =1

Then, according to LS criterion, the filter response
vector is estimated by minimizing error powerfunction and denoted as
G2
G2
Gˆ
w
= arg min r2,opt − s = arg min R N × M w − s

(

w

w

)

⎧⎪r (M + i − j − 1), 0 ≤ j − i ≤ M − 1. To improve
R N ×M (i, j ) = ⎨ 2
⎪⎩0,
other

optimal focusing performance, an iterative LS
algorithm is presented to successively estimate
multiple pre-filters’ coefficients. The estimated pre-filters are used to filter TR reemitted signal inseries. The signal-flow graph of this ILS-PF method
is illustrated in Fig.3.
Pre filter 2
Pre-filter

LS Estimator

LS Estimator"

Pre filter N
Pre-filter

Optimal Focusing Signal

Pre filter 2
Pre-filter

Pre filter 1
Pre-filter

Green’s Function

-0.5

0

0.4

0.8
1.2
Time Axis ( Second )

1.6

2
-3

x 10

Fig.4. normalized signal waveforms of random array TR
focusing experiment

4. Conclusion

The presented ILS-PF method can realize
rapidly optimal TR focusing by three times
transmissions without repetitious transmit-receive
operations needed in the previous methods. On theother hand, the use of a random array permits
placing transducers liberally according to real needs,
which avoids the laborious array calibration.

LS Estimator

Source Signal

TR Signal

0-1

where R N×M is a N × M data matrix and expressed by

Pre filter 1
Pre-filter

Normalized Signal Waveforms in Random Array TR Focusing Experiment1
Source Signal
Focusing Signal
Without Prefiltering
Focusing Signal
0.5With Prefiltering

(11)

−1
G
= RTN ×M R N × M RTN × M s ,TR Focusing Signal

with power of 20 W and resistor of 4 Ω are used as
emitters, and a calibrated B&K 4189 microphone isused as a receiver. The B&K 3560C multi-channel
pulse analyzer is utilized to transmit/receive andrecord operations. A widowed 2-cycle sine impulse
signal with frequency of 20 kHz is used as thesource signal. The speakers are placed randomly on
ground and the microphone is mounted on a bracket
at a height of 1.42 m. Their corresponding plane
coordinates are given as following: speaker 0 (2.92m，2.71 m), speaker 1 (2.10 m，1.92 m), speaker 2(1.92 m, 2.83 m), speaker 3 (1.56 m，2.23 m), themicrophone (2.34 m, 2.48 m). The pre-filter’s
length M is 800 and the iterative number is 10. The
experiment results of normalized signal waveforms
are shown as Fig.4. Obviously, the effectiveness of
the ILS-PF method is confirmed by comparing
these waveforms in this figure.

Normalized Signal Amplititude

where G L, p is a TR transfer matrix and expressed by"Pre-filter
Pre filter N

Acknowledgment
This research was partially supported by the
National Natural Science Foundations of China
under Grant No. 60535030.

Pre-filtered TR Signal

Fig.3 Signal-flow graph of ILS-PF method
3. Experiment results
To verify the presented ILS-PF method, we
conducted the optimal focusing experiment of four-element random array in a small reverberationchamber with dimensions of 5 m (length)×4.9 m(width)×4 m (height). Four commercial speakers

References
1. M. Fink : Phys. Today. 50 (1997) 34.
2. M. Tanter, J.-F. Aubry, J. Gerber, J.-L. Thomas,
and M. Fink：J. Acoust. Soc. Am. 110 (2001) 37.
3. G. Montaldo, M. Tanter and M. Fink：J. Acoust.
Soc. Am. 115 (2004) 768.
4. P. Roux, W. A. Kuperman, W. S. Hodgkiss, H. C.
Song, and T. Akal：J. Acoust. Soc. Am. 116(2004) 1009.

2P5-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 247- 248
11-13 November, 2008

Study of SAW Excitation Efficiency for Novel Gas Sensor
Installed in “Sensor Network”
センサネットワーク用弾性表面波ガスセンサの高性能化の研究
Y.Hiraizumi , H.Aoki, T.Watanabe, J.Matsuda and M.Hikita (Kogakuin University)
平泉康志, 青木宏融, 渡邊友章, 松田潤治, 疋田光孝 (工学院大学)

1.

Introduction

A new concept called “Sensor Network (SN)” hasbeen proposed with the development of mobile
communications system such as cellular phone,radio LAN and Bluetooth. Signals from many
sensor nodes spread in a wide area are gathered to acenter node by a technology similar to that used in
mobile communications. ZigBee has been proposed
as wireless communications medium for SN andregulated by IEEE802.15.4. We have investigated a
new SAW gas sensor taking ZigBee as a basic
communications medium between sensor nodes.
Our proposed SAW gas sensor installed in ZigBee’s
SN can also monitor the hydrogen gas leakage fromfuture fuel-cell cars.
In this study, we designed a novel structure for a
SAW gas sensor. This sensor consists of three
delay-lines formed on piezoelectric single crystals.
Moreover, we utilize fundamental and 3rd-harmonicfrequency signals generated by division andmultiplication of ZigBee’s 2.4GHz signal. By
fundamental/3rd-harmonic frequency method, oursensor can provide large dynamic-range comparedto the conventional SAW sensors. Thus this sensor
can achieve compatibility between energy saving
and high measurement accuracy.

to one another are used in our sensor. As shown in
Fig.1, one length is L for the sensing delay line (D1). The others are L-λ0/8 and L+λ0/8 for D-2 andD-3 respectively, where λ0 is wavelength offundamental frequency wave. D-2 and D-3 which
provide the standard phases are isolated frommeasuring gas. We utilize both fundamental/3rdharmonic waves to detect gas density accurately as
shown in Fig.1. SAW energy concentration is abouta wavelength toward depth in a substrate.
Therefore, the 3rd- harmonic wave is more sensitive
than the fundamental wave against change of
surface propagation condition. We assume thefundamental and the 3rd- harmonic frequencies to be
150 MHz and 450 MHz, respectively. These signals
are generated by 16-time division of ZigBee signal
and 3-time multiplication. For instance, in the caseof low density of gas, the 3rd-harmonic wave isutilized, and in the other case, fundamental-wave isutilized. By this method, the dynamic-range isextremely extended and the measurement accuracy
is improved. However, achieving high excitation
efficiencies for both fundamental/3rd-harmonic
waves is one of our most concerning problems to besolved.

Fundamental

3rd-harmonic

Fig. 2 Phase relations for Fig.1’s three outputs

Fig. 1 Proposed SAW gas sensor for “Sensor
Network“ system

2.

Novel
SAW
gas
sensorrd
fundamental/3 -harmonic waves

utilizingThree delay lines whose delay lengths are different-----------------------------------------------------------am07051@ns.kogakuin.ac.jp

3.

Phase relations for three outputs
fundamental/3rd-harmonic waves

atFig.2 (a) and (b) show relations between output
phases at fundamental/3rd-harmonic waves,respectively. In Fig.(a) assuming the phase of
output (2) to be 0゜, output (3) has 90゜ phase due to
λ0/4-length difference between two delay lines.
Output (1) is located in between as shown in the
figure and moves along the circle depending on

4.

Evaluation and experimental results for IDT
with fundamental/3rd-harmonic waves

We are designing an IDT which can excite
fundamental and 3rd-harmonic waves with almost
same amplitudes. We have investigated doublefinger type IDT with various width of electrodes.
One section schematically illustrated in Fig.3 as an
example is analyzed mathematically. An IDT
consisting of multi-sections is formed byconnecting this section in cascade. Previous
simulation and experimental results for singlefinger type IDT are shown in Fig.4 and Fig.5,
respectively. Our goal is to achieve much better
excitation efficiency using the double-finger type
IDT with fine electrode-width adjustments. Basicexperimental results for the double-finger type IDT
are shown in Fig.6. We continue to do farther
investigation to improve the characteristics.
5. Conclusion
We proposed a novel SAW gas sensor used insensor network. New technologies such as threedelay line structure and utilization of
fundamental/3rd-harmonic waves are introduced in
the sensor. We investigated double-finger IDT withvarious width of electrodes to achieve better
excitation efficiencies for both fundamental/3rdharmonic waves. We continue to improve IDT as
well as to make a basic experiment on our sensor.
Acknowledgment
This study was supported by the Ministry of
Education, Culture, Sport, Science, and Technologyof Japan.
References
1. K.Minami, K.Takimoto, Y.Hiraizumi, and
M.Hikita: Proc. of Symp. on UltrasonicElectronics. Vol.28, 2007, pp.99-100
2. S.Ishikawa, N.Nakaso, N.Takeda, T.Mihara,
Y.Tsukahara, and K.Yamanaka: The Institute ofElectronics. Information and Communication

Engineers. Vol.103, No.340, 2003, pp.73-78.
3. T.Mori, H.Noguchi, and T.Sato: The Institute ofElectronics, Information and Communication
Engineers. Vol.89, No.5, 2006, pp.430-435.

a1,a2,a3,a4: width of electrodes,
b1,b2,b3,b4,b5: interval between electrodes,
L: width of one section
Fig. 3 Investigating double-finger IDT modelfor SAW

Amplitude(a.u.)

surface propagation condition. This phase can bemeasured based on the phases of output (2) and (3).
Almost same relations can be achieved at 3rdharmonic waves as shown Fig.(b). Fig.1’s
configuration
requiresnooscillator
like
conventional ones. Moreover, phase shifts due totemperature are same for these delay lines with any
kinds of piezoelectric substrates, which provides
self-temperature compensation characteristics.

Model 1Model 2Model 3

20

17.5
15

12.5
10
7.5
5
2.5

5ｴ10 7

1ｴ10 8

1.5 ｴ10 8

2ｴ10 8

2.5 ｴ10 8

Frequency (MHz)Fig. 4 Calculated excitation characteristics
for 3 models of single-finger IDT

Fig. 5 One result of Fig.4's models

Fig. 6 Experimental result of double-finger IDT
model

2P5-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 249- 250
11-13 November, 2008

Ball SAW Gas Chromatograph system for
Analysis of Mixed Volatile Organic Compounds
多種類の揮発性有機化合物分析のためのボール SAW ガスクロマトグラフシステム
Yutaro Yamamoto1, Shingo Akao1,2,3, Masanori Sakuma1,2, Kentaro Kobari1,2, Kazuhiro
Noguchi1,3, Noritaka Nakaso1,3, Toshihiro Tsuji1,2 , Kazushi Yamanaka1,2 (1 Tohoku
University, 2 TOPPAN PRINTING CO., LTD., 3 JST CREST)山本祐太朗 1，赤尾慎吾 1,2,3, 佐久間正典 1,3, 小針健太郎 1,3, 野口和洋 2,3, 辻俊宏 1,3, 中曽教尊 2,3,
山中一司 1,3 （1 東北大 工; 2 凸版印刷（株）; 3 JST CREST）

MEMS column

1. Introduction
In the field of security and energy exploitation,a wide variety of volatile organic compounds(VOC) are employed. The gas chromatograph (GC)is frequently used for the multiple-gas sensing but
is not handy. We have developed the ball surface
acoustic wave (SAW) sensor, where SAW with a
specific width is naturally collimated and makes
multiple roundtrips without diffusing by thediffraction, realizing ultra-high sensitivity. [1,2].We also succeeded to downsize the gas
separation column by micro electro mechanicalsystems (MEMS) technology [3,4]. Using them, we
have proposed the ball SAW GC.
In this study, we show a concept of the new ball
SAW GC system using two kinds of MEMS
columns (Fig.1), because it is difficult to analyzeboth heavy and light VOCs by using one kind ofcolumn. We use an open tube(O-T) MEMS column
coated with 5% phenyl 95% methylpolysilarylene
for heavy VOCs and micro packed column withstyrenedivinylbenzene (SDB) micro beads for light
VOCs. The micro packed column is being replaced
by a packed MEMS column fabricated on a siliconwafer.
2. Fabrication of MEMS column
We designed a column diameter of 25mm and acolumn length of 52cm. We touched up existing
method of fabrication of MEMS column[4],channel depth was equalize by Deep Reactive Ion
Etching (DRIE) using a glass as etched stopped
layer. Fabrication of Packed MEMS column isshown in Fig.2 (a). Silicon wafer of 0.5mm
thickness was anodically bonded to the pyrex glassof 0.5mm thickness. After that, the positive photo
resist OFPR-800-LB 200cp (Tokyo Ohka) was spincoated to achieve a thickness of 6µm on the siliconwafer.
-----------------------------------------------------------a8tm5630@stu.material.tohoku.ac.jp

DQD

Open tube column
valve

valve

Packed column

Ball SAW
sensors

Heater

Fig.1 The concept of Dual column ball SAW GC
1: anode bonding

Si substrate (1mm)

Pyrex(0.5mm)
2 : Resist patterning

OFPR 800
UV
Photo mask

development

3 : DRIE ( Deep Reactive Ion Etching )4 : strip

5 : anode bonding(b) Packed MEMS column

Pyrex(0.5mm)

400℃、pressure:10 t
6 : bonding connector−＋

Nano Port

7 : packing silica beads(c) The jacket for withstand pressure(a) Process
Fig.2 Fabrication of micro separation column that uses MEMS
technology

3.

Amplitudechangesensor and a TCD. The sample gases were city gas
including methane (CH4), ethane (C2H6), andpropane (C3H8). Ball SAW sensor was a 3.3mm
LGS single crystal ball without sensitive film. The
flow rate of helium carrier gas was 1.8 ml/min, thecolumn temperature was 40℃, the amount of theinjected sample was 1µl and the split ratio was 5.
We detected three mixed hydrocarbons only by the
amplitude change. Then, we successfully separated
city gas using the very short column of 50cm
length.

TCD (mV)

By using a photomask with a channel width of
440µm and a wall thickness of 500µm, a column
pattern was exposed. The channel of 500µm depth
was etched by DRIE. A pyrex cover glass withholes for the gas inlet/outlet was anodically bonded
to the silicon wafer after the alignment. As joint
connector to GC, Nano ports（Upchurch ScientificInc., U.S.A.）were bonded to the column (Fig.2 b).
We fabricated the jacket made of aluminum tosafely withstand the very high pressure (100atm) on
the MEMS column when packing SDB particles init (Fig.2 c). We sandwiched a silicon rubber of
0.5mm thickness between an aluminum plate andthe column in order to avoid the stressconcentration when we apply a pressure on thecolumn. By using this jacket we succeeded to pack
SDB particles in the column, similarly to packing inliquid chromatograph.
Result and discussion

In preliminary experiments, separation of ahigher hydrocarbon (tridecance) was achieved byusing an OT-MEMS column. A ball SAW sensor
made of a 3.3mm Langasite (LGS) single crystal
ball was driven at a frequency of a 150MHz. Poly
isobutylene (PIB) with a molecular weight of
400,000 was coated on a ball SAW sensor. The
signal to noise (S/N) ratio of the amplitude responseof ball SAW sensor was 40 times higher than that ofa thermal conductivity detector (TCD) used in thestate-of-the-art desktop commercial GC (Shimadzu
GC-2014)(Fig.3).
0.987

0.986

Amplitude change(arb.unit)

0.985
40

41

1

S/N≧170
Great differenceof S/N ratio

TCD (mV)

0.9
20

EthanePropane

0.99
0.98
Methane0.97
3

Methane2
1

EthanePropane00Time (min)10

Fig.4 Response for Methane, Ethane, Propane a) Ball SAW
Amplitude response b) TCD response

4.

Conclusion

For the development of handy dual column ball
SAW GC, we succeeded separation of higherhydrocarbon by OT MEMS column and showed aexcellent sensitivity of ball SAW sensor comparedthat of a TCD. Meanwhile, lower hydrocarbons
were separated by a micro packed column. Then
we fabricated a packed MEMS column with
MEMS technology. In the next stage, lower
hydrocarbons will be analyzed by using a packed
MEMS column. In the future, we introduce
compact valves and pumps and develop a highperformance handy GC system.
References

S/N＝4

10
30

1

Time (min)40

Fig.3 Excellent sensitivity of ball SAW sensor to tridecane

Then, as preliminary experiments of a packed
MEMS column, we fabricated a micro packed
column made of wide bore capillary of 0.53mm
diameters and separation of a lower hydrocarbons
were achieved by using it. Fig. 4 shows thechromatogram of the amplitude of a ball SAW[1] K. Yamanaka, H. Cho, and Y. Tsukahara: Appl. Phys. Lett.
76 (2000) 2729.
[2] K. Yamanaka, S. Ishikawa, N. Nakaso, N. Takeda, D-Y. Sim,T. Mihara, A. Mizukami, I. Satoh, S. Akao and Y. Tsukahara:
IEEE Trans. UFFC. 53 (2006) 793.
[3] N. Iwata, T. Abe, T. Tsuji, T. Mihara, S. Akao, and K.
Yamanaka: Jpn. J. Appl. Phys., 46 (2007) 4532.
[4] S. Akao, N. Iwata, M. Sakuma, H. Onishi, K. Noguchi, T.
Tsuji, N. Nakaso, and K. Yamanaka: Jpn. J. Appl. Phys., 47(2008) 4086.

2P5-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 251- 252
11-13 November, 2008

Development of Orientation Controlled Ball Surface Acoustic
Wave Device with Optimal IDT Position and Analysis of
Propagation Characteristics.
IDT 位置を最適化した方位制御ボール SAW 素子の開発と伝搬特性の評価
Takayuki Yanagisawa1,3†, Tsuneo Ohgi1,3, Noritaka Nakaso1,3, and Kazushi Yamanaka2,3(1TOPPAN PRINTING CO.,LTD., 2Tohoku Univeasity, 3JST.CREST)
柳沢恭行 1,3†，大木恒郎 1,3，中曽尊教 1,3,山中一司 1,3 （1 凸版印刷, 2 東北大, 3JST. CREST）

1. Introduction
We have discovered a phenomenon thatsourface acoustic wave (SAW) on a ball makes
ultramultiple roundtrips, 1) and by using a
piezoelectric single-crystal ball, we can efficiently
excite SAW merely by fabricating an interdigitaltransducer (IDT) on a ball. 2) It is known that
piezoelectric crystals have anisotropic acoustic
properties, and that on the Z-axis cylinder of aquartz ball, the velocity of SAW and power flow
angle (PFA) change periodically. By moving an
IDT close to the quartz ball, we confirmed that theSAW velocity varies with a period of 60°, inagreement with the theoretical value, and succeededin identifying the –Y-axis-equivalent direction. 3) On
the basis of the research findings of the Z-axis
cylinder route, 4) the orientation of the quartz ball
was aligned using an orientation control apparatus(OCA) so that roundtrip of SAW attenuates
exponentially with the smallest disturbance. 5) And
we found that the exponential attenuation wasobserved at specific IDT positions distributed in ameander belt with a period of 120° in agreementwith PFA period. 6) In this study, we developed anorientation controlled ball SAW device with an IDTfabricated on the meander belt, and measured the
propagation characteristics, and investigated the
SAW propagation path on the ball SAW device.
2. Fabrication
We evaluated a degree of disturbance of SAW
attenuation using the coefficient of determination(R2). 6) In φ 3.3mm orientation controlled ball SAW
device, an IDT was fabricated at the position of thehighest SAW velocity, where the meander belt ofhigh R2 position intersected with Z-axis cylinder ofthe quartz ball. The IDT had ten pairs of electrodes,
with a period of 21.38μm and an aperture of
265.59μm. It was designed to create a collimatedSAW beam of wavelength 21.38μm and center
frequency 150MHz at the position of averagevelocity of the Z-axis cylinder. We measured theimpulse response waveform from the ball SAW
device, and the amplitude of the SAW was obtainedby quadrature detection. The amplitude of the SAW
in the developed device on the log scale as afunction of time up to 60 turns is shown in Fig. 1.

Fig. 1 Multiple roundtrip (60turns) of SAW on a quartz
ball SAW device

In Fig. 1, roundtrip of SAW attenuates
exponentially well in agreement with the results ofproximate concave IDT.5-6) In Fig.1, R2 obtained
from the SAW amplitude up to 40 turns was 0.9986,
with slightly high value compared to the result ofproximate concave IDT. 6) The center frequency of
the SAW at the first turn was 151.8MHz. The
experimental phase velocity of the SAW,
representing the position of the IDT, was estimatedfrom its frequency and the IDT period. The
experimental phase velocity was 3245m/s. This
result shows that the IDT was fabricated with anerror within about 7 degrees in longitude direction
by the position where SAW velocity is 3270m/sec,
and the velocity is highest on the Z axis cylinder.
3. Observation of SAW distribution
The OCA for the measurement of the SAW
distribution is shown in Fig. 2. The developed ball
SAW device was installed in the positioning stage.
The pattern of IDT of the glass plate was identicalto the IDT of the ball SAW device. The impulse
signal was generated with the pulser, and the SAW
was generated by the IDT of the ball SAW device.
The IDT of the glass plate was moved towards thecenter of the ball SAW device, and was in slight
contact with the device. The SAW on the
propagation path was received by the IDT of theglass plate, and transmitted via a matching circuit
and Amp. This waveform was recorded by a digitalFig. 3 Amplitude distribution of cw and ccw SAW propagation

oscilloscope and transmitted to PC and analyzed.
The ball SAW device was rotated by 360° with 15°
steps around the Z-axis (angle φ), and rotatedaround the x-axis with latitudes of 0°, ±1.5° ±3°,±4.5°, ±6° (angle ψ) and the waveform at each step
was recorded. The amplitude of the cw SAW andthe ccw SAW viewed from +Z-axis were obtained
from the waveform, and mapped to the SAW
distribution at each turn. The cw and ccw SAW
distribution at 1 and 2 turns are shown in Fig.3. But,
because an electrical feedthrough from the IDT ofthe device, and the interference of cw and ccw SAW,
the area near the IDT and different by 180° in φ is
not shown in Fig.3. The rotation angle φ= 0° whenthe IDT of the device was just under that of theglass plate, and the cw rotation was defined as the
positive direction. In Fig.3, amplitude of both cw
and ccw propagating SAW were distributed in ameander pattern with a period of 120° around the
Z-axis cylinder. This pattern was almost identical tothe previously observed meander belt 6), where
exponential decay of multiple roundtrip SAW wasobserved without disturbance when SAW was
generated and detected by a proximate concave IDT
located at each position in it.
BPF

Matching
circuitz-axisψball SAW
devicey-axisφ

BPF

Matching
circuit

x-axisPulserOscilloscopePC

ccw SAW
cw SAWAmp
IDT onglass plate

positioning
stage

Fig. 2 Schematic of measurement system

In another ball SAW device in which IDT
position was uncertain and the attenuation of SAW
was disturbed, the propagation path was irregular(not shown in this paper) unlike the path of thedeveloped device. In future work, we will make atest device where an IDT is fabricated at awell-defined position out of the meander belt, andinvestigate the propagation path.
4. Conclusions
Fabricating an IDT at an optimal position
proximate IDT, we developed a orientation
controlled ball SAW device in which roundtrip of
SAW attenuates exponentially with a large R2. The
SAW propagation path was identical to the meander
belt of the specific positions of proximate IDT
where SAW attenuate exponentially without
disturbance.
References
1. K. Yamanaka, H. Cho, and Y. Tsukahara: Appl.
Phys.Lett. 76, 2797 (2000)
2. N. Nakaso Y.Tshukahara, S. Ishikawa and K.
Yamanaka: Proc. 2002 IEEE Ultrason. Symp.
47.
3. S. Kai, K. Ote, T. Mihara, T. Ohgi, N Nakaso, I.
Satoh, T. Fukiura, H. Tanaka, K. Yamanaka:
Jpn. J. Apply. Phys. Vol. 46, No. 7B, 2007, pp.
4723-4725
4. S. Kai, K. Ote, T. Mihara, T. Ohgi, N. Nakaso, I.
Satoh, T. Fukiura, H. Tanaka, and K. Yamanaka:
Jpn. J. Appl. Phys. 46, No. 7B, (2007), 4723
5. K. Ote, T. Yanagisawa, S. Akao, N. Nakaso, andK. Yamanaka: Technical Report of IEICE
US2007-46, (2007), 19-46 [in Japanese]
6. T. Yanagisawa, K. Ote, T. Ohgi, N. Nakaso, andK. Yamanaka Jpn. J. Appl. Phys.47, No.7,(2008), 4081

2P5-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 253- 254
11-13 November, 2008

Fabrication of Thin Sensitive Film of Ball SAW Sensor
Using Off-Axis Spin Coating Method
軸外スピンコート法を用いたボール SAW センサの感応膜の作製
Kentaro Kobari1, 2‡, Yutaro Yamamoto1, 2, Masanori Sakuma1, 2, Shingo Akao1, 2, 3,
Toshihiro Tsuji1, 2 and Kazushi Yamanaka1, 2 (1Tohoku Univ.; 2JST,CREST; 3TOPPANPRINTING CO., LTD.)
小針健太郎1, 2‡，山本祐太朗1, 2，佐久間正典1, 2，赤尾慎吾1, 2, 3，辻俊宏1, 2，山中一司1, 2（1東北大 工; 2JST,CREST; 3凸版印刷）

1. Introduction
It is needed to detect hazard gases at low
concentration for environment assessment andsecurity, and small portable sensor is needed formonitoring those gases. Ball surface acoustic wave
(SAW) sensor is suitable for these purposes, since
the ultra-multiple roundtrips (>100 turns) of thecollimated SAW along an equator of the ballrealizes ultra-high sensitivity [1-3]. Attenuationinduced by the sensitive film coated on theroundtrip route must be low not to hinder theultra-multiple roundtrip, and thus the film must be
thin (submicron thickness) and highly uniform.
However, conventional spin coating method (Fig.1)
where centrifugal force is normal to surface of theroute and the liquid (solution of sensitive film)
might be left thick there, could not fabricate thefilm that fulfills these requirements. Therefore, we
propose “off-axis spin coating” method andevaluate sensitive films fabricated by this method.
Rotation axis(a)Sensitive
film

(b)

Direction ofcentrifugal force
1.65 mm

3.3 mm ballRoundtrip routeof SAW
VacuumVacuumchuck

Fig.1 Schematic diagram of conventional spin coating
method (a) and cross-section drawing of the vacuum
chuck (b)2. Principle of off-axis spin coating method
Centrifugal acceleration g ' that act on therotation body is given by
g ' = rω 2
(1)
where r is the radius of rotation and ω is theangular velocity. In the conventional method, r isnaturally short because it equals to radius of the ball(=1.65 mm). In the off-axis spin coating method,g ' is larger than that in the conventional methodby a longer r . In this method (Fig.2), a ball isclamped at an off axis position ( r =6.85 mm).

Moreover, the direction of centrifugal force isparallel to surface of the roundtrip route, and it
would promote the liquid flow away from the route,then leading to thinner film.
In this study, we applied these methods tolangasite (LGS) balls with 3.3 mm diameter.
Sensitive film material was polyisopurene (PIP)
that has sensitivity to some chemical agents [4], andsolvent was benzene. The solution concentrations
were 0.2 wt% for conventional method and 1.0 wt%
for both methods. Rotation speeds were 5000 rpm
in conventional method and 3000 rpm in off-axis
method, and then centrifugal accelerations of 46 G
and 69 G acted on the route, respectively.
Direction of(b)centrifugal force(a)Rotationaxis(b)

3.3 mm ballRoundtrip routeof SAW
6.85 mm

VacuumSensitive film

Gel sheet(1.5 mm)
Vacuum chuck

Fig.2 Schematic diagram of off-axis spin coating
method (a) and cross-section drawing of the vacuum
chuck (b)3. Evaluation of film
The PIP films coated with 1.0 wt% solution
were scratched around the route, and the thickness
was measured (Fig.3). The film fabricated by theconventional method was about 100 nm thick. On
the other hand, the film fabricated by the off-axis
method was thinner (~ 40 nm).
Next, sensitive films were coated on two ball
SAW sensors by using these methods. And theattenuation changes before and after coating were
measured. These were seriously large as 800 dB/m
and 3000 dB/m under the conventional method, andavailable roundtrips were only 2 turns and 1 turn,respectively. Under the off-axis method, in contrast,
attenuations were quite low as 60 dB/m and 37
dB/m, and thus available roundtrips were 34 turns
and 40 turn, respectively. Therefore the off-axis
method proved useful for the multiple roundtrips.

LGS
substrate

PIP
film
(c)
0

10 µm 1.85

1.04
µm
1.2

µm

(f)

Distance (µm)

2

1.9

1.1
100

50

2.15
LGS
substrate

PIP
film

Hight
(µm)

10 µm

1.34 (e)

Hight
(µm)

(b)

0

50

100

Distance (µm)

NonaneOctaneHeptaneHexane10

Amplitudechange(arb. unit)

0
1
0.9
0.8

1

1

10

10

0

0

10

10

–1

10

–1

10

PIP 1.0 wt%
PIP 1.0 wt%
PIP 0.2 wt%

–2

10

0

10
1

(b)

TCD (mV)

1
0
1

2Time (min)

3

DMMP

Delay timechange (ppm)

0

10

0

0

10

–1

–1

10

10
PIP 1.0 wt%
PIP 1.0 wt%

–2

–2

10

10
1

10

2

10

3

10

Fig.5 Detection efficiencies and noise levels of delay
time change for DMMP obtained with sensors coatedby conventional spin coating method (a), and off-axis
spin coating method (b). Positions of slope show
efficiencies and dashed lines show noise levels.
Circles and triangle show detection limits.

5. Conclusion
Off-axis spin coating method was proposed tofabricate thin and uniform sensitive films. It
enabled enhanced multiple roundtrips, and higher
detection efficiency in ball SAW sensors.

0

Amplitudechange(arb. unit)

1

10Consentration (ppm)

2

3

10

10

0

1

0.9
0.8

TCD (mV)

2

10

10

10

(b)

1

10

Consentration (ppm)–210Noise Level (ppm)(a)

Delay timechange (ppm)

4. Evaluation of sensor coated by off-axis spin
coating method
Fig.4 shows the responses of the ball SAW
sensor coated by off-axis method (34tunes). The
sample gases were four mixed higher hydrocarbons(hexane, heptane, octane and nonane) and a nerve
gas simulant (dimethyl methylphosphonate;
DMMP). [5](a)Noise Level (ppm)

Fig.3 Optical microscope images (a),(d) andtopographies (b),(e) of the PIP films coated byconventional method and off-axis method,respectively. (c),(f) Profiles along the dashed lines in(b),(e), respectively.

Delay Time Change (ppm)

propagationroot
500 µm500 µmThe noise level was 0.02 ppm as an effect ofmultiple roundtrips (b). The (detection) efficiency
defined as the delay time change (ppm) per 1000
ppm gas concentration of DMMP was 23.1
ppm/1000ppm, giving detection limit (sensitivity)of 0.8 ppm.
Fig.5 shows efficiencies and noise levels for
DMMP in conventional (a) and off-axis method (b).
Whereas efficiencies of sensors coated with 1.0
wt% PIP showed considerable variation inconventional method, these in off-axis method washighly reproducible. The film fabricated byconventional method with 0.2wt% PIP showed low
attenuation and allowed 50 turns. This sensor
showed low noise level, but the detection efficiency
was low and the detection limit was 4 ppm larger
than that in the off-axis method.

Delay Time Change (ppm)

(d)

n
tio
ga
pa
prooot
r

(a)

0.1

0
0

Time (min)Fig.4 Responses of ball SAW sensor and TCD for
detecting four mixed higher hydrocarbons (a) and
DMMP (b).

References
1. K. Yamanaka et al.: Appl. Phys. Lett. 76 (2000)
2797.
2. K. Yamanaka et al.: IEEE Trans. Ultrason.
Ferroelecotr. Freq. Control 53 (2006) 793.
3. N. Iwata et al.: Jpn. J. Appl. Phys. 46 (2007) 4572.
4. B.S. Joo et al.: Sens. Actuators B 121 (2007) 47.
5. S. Akao et al.: Jpn. J. Appl. Phys. 47 (2008) 4086.

2P5-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 255- 256
11-13 November, 2008

Development of Odor Display Device Using Surface
Acoustic Wave
弾性表面波を用いた匂い供給装置の開発
Taro Monji†, Atsushi Saitoh and Toru Nomura (Facult. Eng., Shibaura Inst. of Tech.)
文字太郎，齋藤敦史，野村徹 （芝浦工大 工）

1. Introduction
Odor sensing system using multiple sensors
with different characteristics and patternrecognition technique has studied by many
researchers1. And, numeric conversion of odors has
become possible by such systems. In the result, thedemands for the virtualization of olfactory sense
have risen to achieve higher reality in the field of
virtual reality. There are various types of display
systems that can present aural, visual and haptic
information, in the field. It is also important topresent olfactory information. And, “Olfactory
display” will realize that.
Many approaches have been performed thedevelopment of olfactory display system, and theodor supplying method2. However, the device
which enables to synthesize some odors, and to
supplies the synthesized odor effectively, rapidly isdeveloping.
In this paper, we describe about an odor
supplying device by using surface acoustic wave
(SAW) device. The principle of supplying odor is“SAW streaming phenomenon”3. SAW streaming is
the phenomenon that the liquid on the surface of the
SAW is streamed, flight or atomized toward thewave propagating direction. The movement of theliquid depends on the input power of SAW. If the
SAW streaming can be used, odor supplying device
which enables from the mixture of odor constituentsin the liquid state to evaporation in the same motion
will be achieved.
2. SAW streaming phenomenon
SAW devices are extensively used as analog
electrical filters for mobile and wirelesscommunications. A Rayleigh wave is a true SAW,
which has an elliptical displacement on the surface
due to the combination of a displacement in the
direction parallel to the SAW propagation and that
normal to the SAW propagation surface. The true
SAW is attenuated and radiates the energy into aliquid, if the liquid is placed on the propagation
path of SAW. The liquid streams to the propagation
direction of SAW by the radiated longitudinal wave
by the radiation of the energy. Furthermore, if SAW

input voltage is increased, droplet is jet streams inpropagation direction. This phenomenon is called as
SAW streaming. Fig. 1 shows the image of SAW
streaming phenomenon. The radiation angle θR
depends on the ratio at the velocity of thelongitudinal wave in the liquid and the propagation
velocity of SAW on the piezo-electric substrate.
The angle θR is obtained from the following
expressions.

θR = sin-1VL/VR(1)

Here, VL is the propagation velocity of thelongitudinal wave into a liquid, and VR is the
propagation velocity of the SAW.
θR

A ir

L iq uid

ID T
R ay le ig h S A W

1 2 8 Y X -L iN bO 3

Fig 1. Schematics of SAW steaming
3.

SAW device for liquid pump

A liquid pump was fabricated for handlingodor constituents in liquid state. A 128° rotated
Y-cut X-propagating LiNbO3 was used as
piezoelectoric substrate. An interdigital transducer(IDT) with 20 finger pairs, apertures of 0.5 mm,
and a center frequency of 100 MHz was designed
and fabricated on it. And, a grating reflector was
also fabricated on the device for propagating SAW
in one direction. All electrodes were made of Ti/Pt.
Fig. 2 shows the schematics of the device structure.
R e fle c to r

ID T

Fig.2 A device for a liquid pump

A volatile organic solvent (VOC) which wasodor constituent were loaded on the surface of thedevice and the flow phenomenon of the liquid wasobserved with a digital microscope. The volume ofa liquid sample was 2µl. The result of observing theflow of a liquid sample is shown in fig.3. In thiscase, the sample is 2- butanone. It was confirmedthat the flow of the liquid was caused by ON/OFFof the external input to the device instantaneously.
Moreover, the amplitude of input signal was about
5VP-P, when the liquid flew at a enough flow

the shorted propagation pass. The amplitude of
input signal to the SAW device was about 10.81VP-P.
In the case of the experiments on the shorted
channel, All VOCs used at our experiment wereatomized by supplying the input signal with theamplitude about 10 ~ 12VP-P. However, some VOCs
could not be atomized by using the opened surface.
We thought that the result was caused by thedifference of the interaction between the surface ofthe device and liquid sample. The contact angle of aliquid on the device surface was measured as anindex of the strength of the interaction. The liquid
used was pure water in the experiment. When thecontact angle had been measured, it was 72 degree
on the opened surface, 80 degree on the shorted
surface. As a result, it is understood that the shorted
surface has stronger hydrophobicity than theopened surface. It is thought that the difference ofthe hydrophobicity on the surface influenced thephenomenon of atomization.

Fig.3 The flow of acetone by SAW streaming

rate. In that time, the electric power was about
0.06W. The flowing was also observed in anothersamples (Nine kinds of samples were used. alcohols,
ketones, and hydrocarbons, etc.).
4.

SAW device for atomization

In the case of atomizer for VOCs, the same
substrate was used as the SAW pump. Two IDTs
with 20 finger pairs, apertures of 4.8 mm, and acenter frequency of 32 MHz was designed andfabricated on it. And, grating reflectors were alsofabricated each outside of IDTs on the device forfabricating a two port resonator. One of the surfaceof the propagation pass was shorted, and the otherwas opened. All electrodes were made of Cr/Au.
The structure of the device for atomization of
VOCs is shown in fig. 4. In the case of atomization,
RF amplifiers were used, because larger input
power was necessary compared with the case of
liquid pump.

IN ①

IN ②
O PEN
GND
SHORT

IN ③

IN ④

Fig.4 The device for atomization
The appearance of atomization is shown in
fig.5. Fig.5 is the result that was loaded acetone on

Fig.5 Atomization by SAW streaming
5.

Conclusions

Our purpose is development of a odor
supplying device which have the function of mixing.
The liquid pump and the atomizer for VOCs using
SAW streaming was used for the attainment of our
purpose. As a result, both of the pump and theatomizer satisfied a basic demand. In the future,
multi-channel pumps and an atomizer will be
integrated on a substrate for the operation from the
mixture of odor constituents in the liquid state toevaporation in the same motion.
Acknowledgment
This work was financially supported by the Japan
Society for the Promotion of Science, Grant-in-Aid
for Exploratory Research, No-166550046.
References
1. J.Ide, T.Nakamoto, and T.Moriizumi,: The
Technical Digest of the 13th Sensor Symposium,(1995), pp.57 – 60.
2. T.Nakamoto, T.Yamanaka and R.Matsumoto:
Proc. Multisensor Fusion and Integration forIntelligent Systems 2001, (2001) pp.13-18.
3. S. Shirakawa, J. Esaki and I. Tomonaga: Jpn. J.
Appl. Phys. 46 (2006) 1358.

2P5-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 257- 258
11-13 November, 2008

Micro-Laboratory on SAW piezoelectric crystal
SAW 圧電結晶を用いたマイクロ実験室
Noriyuki Yasuda†, Mitsunori Sugimoto and Jun Kondoh (Shizuoka University)

安田宣之‡，杉本光範，近藤淳 (静岡大学）

1. Introduction
IDE
LCR
meter

SiO2 or LiNbO3

Fig. 1 IDE sensor system.
80
70

Impedance(kΩ)

Sensors using microscaled interdigitatedelectrode arrays (IDEs) have been investigated[1].
Generally, the IDEs are fabricated on a glass (SiO2)
plate. Features of the IDEs are high sensitivity
and quick response. If a piezoelectric substrate,
such as 128YX-LiNbO3, is used as a substrate, anovel device will be realized. An interdigitaltransducer (IDT) which has the same structure with
the IDE is capable of generating a surface acoustic
wave (SAW). Liquid droplet is moved by theSAW[2]. Therefore, by fabricating the IDE sensors
on the LiNbO3 substrate, an integration system of aliquid sensor and a liquid actuator named the“Micro-Laboratory” is realized. First, the IDE on
128YX-LiNbO3 is compared with it on SiO2.
Then a novel micro-laboratory on 128YX-LiNbO3
is fabricated and demonstrated.

50
40

SiO2
LiNbO330

2. IDE sensor

20

The IDE sensor system is shown in Fig. 1.
The IDE sensors on SiO2 or LiNbO3 are connected
to LCR meter (HP 4285A).
Fig. 2 shows
impedance spectrum at 100 kHz. Samples were
glycerol/water mixtures. The results indicate thatthe impedance is independent of substrate materials.
To evaluate the results, a simplified
equivalent circuit model[1] as shown in Fig. 3 wasused. The resistance of the solution, Rsol, and thedielectric capacitance, Cde, are represented
following equations.

0

20

40

60

80

100

Concentration of glycerol(wt%)

Fig. 2 Impedance spectrum of IDE sensors
on SiO2 and LiNbO3.
Rsol

Cde

（1）

Fig. 3 Model of equivalent circuit.
80
70

（2）

Where n is the number of the interdigitatedelectrodes, l the length of the fingers, κ theconductivity of the solution, ε the permittivity ofthe dielectric, w the electrode width, L two times w
and K the complete elliptic integral of the first kind.
-----------------------------------------------------------f0730330@ipc.shizuoka.ac.jp

Impeadance(kΩ)πw ⎞⎛2 K ⎜ sin
⎟
1 1
2L ⎠
⎝
R sol =πw ⎞nl κ ⎛
K ⎜ cos
⎟
2L ⎠
⎝
πw ⎞
⎛
K ⎜ cos⎟
2L ⎠⎝C de = nl επw ⎞⎛2 K ⎜ sin
⎟
2L ⎠
⎝

60

60
50

SiO2
LiNbO3
theory

40
30
20
0

20

40

60

80

100

Concentration of glycerol(wt%)

Fig. 4 Comparison of measurements with theory.

Calculated results of eqs.(1) and (2) and the results
are plotted on Fig. 4. The measured results agreewith the theoretical values. The similar results
were obtained at different frequencies (75k，200k，
300k，450k，600k, 1MHz).

Vibrate→Stream→Jet
Applied voltage

3.2. Mixing of liquid droplets with SAW
Micro-laboratory
wasfabricatedon
128YX-LiNbO3 as shown in Fig. 6. The SAW
was generated from the IDT and the measurements
were performed by the IDE sensor. Distilled water(DW) and glycerol (100 wt%) were mixed and four
different concentrations (20, 40, 60, 80 wt%) ofglycerol/water mixtures were produced. Fig. 7
shows the process. Fig. 8 shows the measured
results using the IDE sensor at 100kHz. For
comparison, the results of premixed glycerol/water
mixtures (liquids were not mixed by SAW) are alsoplotted.
In the case of without-SAW, themeasurement error of the IDE sensor is large
because glycerol/water mixtures have large
viscosity. In the case of with-SAW, however, themeasurement error was improved because liquids
ware uniformly mixed by SAW.

Leaky-SAW

Rayleigh-SAW

128YX-LiNbO3

Fig. 5 Principal of SAW streaming.
Signalgenerator

Functionsynthesizer

LCR meter

IDT

RF-AMP

IDE

SAW

Antennatuner
128YX-LiNbO3

Fig. 6 Mixing and Sensing device.
IDE

IDT

SAW
Glycerol

DW

SAW

4. Conclusion
The “Micro-Laboratory” as a new
application on SAW piezoelectric crystal ispresented.
This “Micro-Laboratory” has acharacteristic of which the amount of samples is by
the microliter.
In the future, we will perform the study on
the disposable SAW device with the three layer
structure[3] for the application to the biotechnology.

Mixed liquid（DW + Glycerol）

Fig. 7 Process of mixing liquids.
60
50

Impedance(kΩ)

References[1]. Peter Van Gerwen et al., “Nanoscaled
interdigitated electrode arrays for biochemicalsensors, ” Sens. & Act. B, 49, pp.73-80, 1998.
[2]. S. Shiokawa.et al., “Experimental study on
liquid streaming by SAW, ” Jpn. J. Appl.
Phys.,vol. 28, Suppl. 28-1, pp.126-128, 1988.
[3]. M. Satou et al., “SAW streaming phenomen
on in isotropic material/liquid/piezo-electric
crystal structure, ” US2007-80, pp31-35, 2007
[in Japanese].

LiquidIDT

3. Micro-laboratory on 128YX-LiNbO3
3.1. SAW streaming phenomena
When a liquid is placed on a SAW
propagating surface, a longitudinal wave is radiatedinto liquid as shown Fig. 5. The liquid vibrates,
streams and jets with increasing SAW amplitude.
This phenomenon is known as SAW streaming[2].
In this work, SAW streaming was used tocontrolled.

θR

40
30

without-SAW
with-SAW

20
10
0

20

40

60

80

1 00

Concentration of glycerol(wt%)

Fig. 8 Impedance spectrum of glycerol/water
mixtures without-SAW and with-SAW.

2P5-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 259- 260
11-13 November, 2008

Measurements of standard viscosity liquid using shear horizontal
surface acoustic wave sensor
横波型弾性表面波を用いた粘度標準液の測定
Takeshi Morita†, Mitsunori Sugimoto and Jun Kondoh (Shizuoka Univ.)
森田武‡，杉本光範，近藤淳 （静岡大学）

1. Introduction
A liquid-phase sensor is realized with a shear
horizontal surface acoustic wave (SH-SAW) device.
As the SH-SAW sensor can detect liquid properties,
such as conductivity, dielectric constant, viscosityand density, it has great attractions for liquidevaluations.
In previous works[1], we found that sensor
responses for viscosity standard liquids depend on asensor frequency due to viscoelastic properties ofthe liquids. In this paper, we report theoretical andexperimental consideration about viscosity standard
liquids.
The SH-SAW sensors with different
frequencies are used. A simple viscoelastic model
is applied to explain the experimental results.
2. Theory
2.1 Maxwell model
A viscoelastic liquid has viscous and elastic
properties. The liquid is modeled by a Maxwell
model[2], as shown in Fig. 1. Maxwell model isexpressed in series with spring and dashpot.
Behavior of the Maxwell model depends onfrequency: at low frequency, it acts a viscous liquidand spring can be ignored. When the frequency
increases, influence of the spring appears. In thispaper, theoretical equation for the SH-SAW sensor
is derived on the basis of the Maxwell model.
2.2 Theoretical formula
Relationship between stress, T, and strain, S,
for the Maxwell model is expressed in eq. (1).
∂S
1
1 ∂T
= T +
∂t
G ∂t
η

(1)

Here, η is viscosity and G is a shear module.

G

Fig.1

η

Maxwell model-----------------------------------------------------------f0730329@ipc.shizuoka.ac.jp

When time variation of strain is assumed as e jωt ,the relationships between stress and strain are
exchanged as following equation.
T =

j ωη
S
1 + jω τ(2)Here, ω is the angular frequency and τ is arelaxation time (τ =η / G) . Equation (2) indicates:when ωτ<1, behavior of the Maxwell model
behaves like viscosity fluid. On the other hand,when ωτ>1, it acts as viscoelasticity.
Surface acoustic impedance, Z, for the
Maxwell model is given from eq. (2) as follows[2].
⎡
μ
⎢− j
V
⎢
⎢
Z =⎢
⎢
⎢
⎢
⎢⎣

1−
0

λ
V

ρV 2
μ
ωη
V

1−
0

⎤
⎥
⎥
⎥
⎥
0
⎥
λ + 2μρV 2 ⎥⎥− j1−
λ + 2 μ ⎥⎦
V

μ

0

V

ρV 2
μ

Where V is the propagation velocity, and ρ is thedensity of sample liquid, μ and λ are shown in Ref.
[2]. By substituting imaginary part of Z into eq.
(3), velocity shift (ΔV/V) for the Maxwell model,
eq. (4), is derived.
ΔV= − A ( v n・ Z・' vn )
i v n + v n・ Z i ・
V

(3)

1
⎡1
ΔV
ωρ'η ' ⎤22= − A' ⎢ (M1 + M 2 ) 4 sin(M 3 ) −
⎥
2 ⎦
V
⎣V

(4)

Here,
M1 =

ω 2 ρητ V 2(ωη ) 2 − (ω 2ητ ) 2+{1 − (ωτ ) 2 } 2 + ( 2ωτ ) 2
1 + (ωτ ) 2⎛ ρV 2⎞2ω 2ητ
⎟−M 2 = ωη ⎜⎜
2
2 2
2 ⎟
{1 − (ωτ ) } + ( 2ωτ ) ⎠⎝ 1 + (ωτ )⎛M ⎞1
M 3 = tan −1 ⎜⎜ 2 ⎟⎟2
⎝ M1 ⎠
Where ρ' and η' are density and viscosity of areference liquid, and A and A' are material
constants.

1

Vectorvoltmeter

50MHz
-4

ΔV／V（×10 )Signalgenerator

LiquidFig.2

SH-SAW

0

-1

-3
0

5

10

Using the SH-SAW sensors, we measured theviscosity standard liquids.
The experimental
results are shown in Fig. 3. The abscissa is squareroot of density and viscosity products.
The
ordinate is the velocity shift.
For a Newtonian fluid, the velocity shift is
proportional in ρη . At low ρη , sensor responses
However they areare proportional in ρη .
saturated with increasing ρη due to viscoelastic
effect.
As the shear modulus of the viscosity
standard liquid is unknown, it is difficult tocompare eq. (4) with the experimental results. So,
we calculate G using eq. (4). These results areshown in Fig. 4. The abscissa is square root of
density and viscosity products. The ordinate is theshear elasticity. The shear moduli are proportionalin ρη and dependent on frequency.
5. Conclusions
Using the SH-SAW sensors with different
frequencies, we measured the viscosity standard
liquids. From the results, we found frequency
dependency of the viscosity standard. We foundthat velocity change depends on the sensor
frequency.
Using eq. (4), we estimated the shear moduli.
First we tried to compare eq. (4) with experimental

15

20

25

30

35

(ρη)0.5 (kg2 m -4 s-1 )0.5

3. Experimental

4. Results and discussion

100ＭHz-2

Measurement system

Fig.3 Measurement value for changing the center
frequencies
250
30MHz

50MHz

100MHｚ200

G (MPa)A vector voltmeter measurement system (seeFig. 2) was used to measure viscosity standard
liquids. A signal from a signal generator was fed
to the SH-SAW sensor. The output from thesensor which is phase shift was monitored using
the vector voltmeter.
In this paper, a 36YX-LiTaO3 substrate wasused as an SH-SAW sensor substrate. The center
frequencies of the SH-SAW sensors were 30, 50,
and 100 MHz, respectively.

30MHz

150
100
50
0
0

10

20

30

(ρη)0.5 (kg2m-4 s-1 )0.5

40

Fig.4 Shear elasticity value for changing the center
frequencies
results. However, the shear moduli of the samples
at the measured frequencies have not been reported.
Therefore, we estimated the shear moduli
substituting the results and material constants ofsample density and viscosity.
In this paper, we assumed that the density andviscosity of samples are independent of frequency.
In future work, simultaneous estimation method ofdensity, viscosity and the shear moduli will beestablished.
Acknowledgement
This work was partially supported by NEDO andHFSPO.
References[1]. T. Morita et al.: Autumn Meeting of AcousticalSociety of Japan, 2-P-15 (2007).
[2]. J. Kondoh: Doctor Thesis, Shizuoka University(1995) (in Japanese)

2P6-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 261- 262
11-13 November, 2008

Numerical Simulations of Acoustic Cavitation Noise
with Temporal Variation of the Number of Bubbles
気泡数の変動を取り入れたキャビテーション・ノイズの数値シ
ミュレーション
Kyuichi Yasui†, Toru Tuziuti, Judy Lee, Teruyuki Kozuka, Atsuya Towata,
and Yasuo Iida (AIST)†

安井久一 ，辻内亨，Judy Lee, 小塚晃透, 砥綿篤哉, 飯田康夫（産総研）

1. Introduction
Pulsating bubbles under intense ultrasoundemit acoustic waves especially at the end of the
bubble collapse when shock wave is emitted into
the liquid.1) The noise due to acoustic cavitation iscalled acoustic cavitation noise. The frequency
spectrum of acoustic cavitation noise consists of thedriving frequency, its harmonics, subharmonics,
ultraharmonics, and the continuum called “white
noise”.2) As the origin of the “white noise”, twoideas have been proposed. One is the acoustic
signals due to the shock-waves emitted frombubbles.3) The other is the acoustic waves radiatedfrom chaotically pulsating bubbles.4) In the present
study, the origin of the “white noise” is discussed
based on the numerical simulations with thetemporal variation of the number of bubbles.
Ashokkumar et al.5) measured the acoustic
cavitation noise in pure water and aqueous SDS(surfactant) solutions irradiated by 515 kHz
ultrasound. The intensity of the “white noise” ismuch stronger in pure water than that in low
concentration (0.5-2 mM) SDS solutions.
Furthermore, the intensity of ultraharmonics ismuch stronger in pure water than that in low
concentration SDS solutions.

2. ModelThe pressure (p) of an acoustic wave radiatedfrom a pulsating bubble is approximately expressedby Eq. (1).6)&& + 2 RR& 2 / r(1)
p = ρ R2R
where ρ is the liquid density, R is the bubble radius,
the dot denotes the time derivative, and r is the
distance from a bubble.

()

Here we consider a bubble cloud in whichbubbles are spatially uniformly distributed.
Furthermore, the ambient bubble radius, which isdefined as the radius of a bubble when ultrasound is-----------------------------------------------------------†e-mail address:k.yasui@aist.go.jp

absent, is assumed to be the same for all the bubbles.
Then, the pressure (P) of acoustic waves radiatedfrom the bubbles in the bubble cloud is expressedby Eq. (2).
NN&& + 2 R R& 2 ⎛⎜ ∑ 1 / r ⎞⎟ (2)P = ∑ pi = ρ R 2 R
ii =1⎝ i =1⎠
where the sum is for all the bubbles in the bubble
cloud, pi is the pressure of an acoustic wave
radiated from the bubble numbered i, and ri is the
distance from the bubble numbered i. When theobservation point (the position of a hydrophone) isin the bubble cloud, Eq. (2) is expressed by using
the “coupling strength” (S) of the bubble cloud
defined by Eq. (3).7)
S = ∑1 / ri
(3)

(

(

&& + 2 RR& 2
P = Sρ R 2 R

)

)

(4)

Next, we will discuss the response of thehydrophone. In the experiment of Ashokkumar etal.,5) the hydrophone has a flat, usable response up
to 10 MHz. Such hydrophone characteristics can beapproximately modeled by a low-pass filter
expressed by Eq. (5).6)

U&& + 2γπf 0U& + 4π 2 f 02U = P (t ) + p S (t ) (5)where U is the hydrophone signal, γ is thecoefficient for damping, f0 is the cut-off frequencyof the hydrophone, P(t) is the instantaneouspressure of acoustic waves radiated from bubbles
given by Eq. (4), and ps(t) is the instantaneouspressure of the driving ultrasound.
The model of the bubble pulsation taking into
account the bubble-bubble interaction has been
described in Ref. 7.
As a bubble has its own lifetime due to its
fragmentation or coalescence, the number of
bubbles may vary with time. As the number of
bubbles changes, the “coupling strength” defined by
Eq. (3) changes because it is a function of thenumber of bubbles.7) Thus the temporal fluctuationof the number of bubbles can be modeled by the
random variation of the “coupling strength” as Eq.
(6).

S (t + T ) = S (t ) + (∆S )rn(6)

where S(t+T) and S(t) are the “coupling strength” attime t+T and t, respectively, T is the acoustic period,∆S is the maximum amplitude of the temporalfluctuation of S, and rn is the random number
generated by a computer from -1 to 1. The change
of S by Eq. (6) is once an acoustic cycle.
3.

Results and discussions

In the present study, numerical simulationsof the acoustic cavitation noise have been
performed under the experimental condition of
Ashokkumar et al.5) According to Lee et al.8), theambient radii of sonoluminescing bubbles in purewater range from 2.8 – 3.7 µm at 515 kHz.

7

Hydrophone signal (a.u.)

10

6

10

4.

5

10

4

10

0

2000

4000

6000

8000

10000

Frequency (kHz)Hydrophone signal (a.u.)

In Fig.1, the calculated frequency
spectra of the acoustic cavitation noise have beenshown without (the upper graph)) and with (thelower graph) the temporal fluctuation of the numberof bubbles when the acoustic pressure is 2.6 bar andthe ambient bubble radius is 3 µm. The initialcoupling strength is S0=104 m-1, which corresponds
to the number of bubbles of about 50 at around ananti-nodal plane in a cylinder of 30 mm in diameter.
For the lower graph, the amplitude of the temporalfluctuation of the coupling strength is 0.2 S0.
With the temporal fluctuation of the number of
bubbles, the continuum (white noise) is muchstronger than that without it. Thus it is concluded
that the temporal fluctuation of the number of
bubbles results in the generation of the white noise.
According to the present numericalsimulations, the intensity of the white noise ishigher for higher acoustic pressure, larger numberof bubbles, and larger amplitude of the temporalvariation of the number of bubbles. Furthermore,
the white noise is stronger for the ambient bubble
radius (R0) of 3 µm which is typical in pure water
than that for R0=1.5 µm which is typical in low
concentration SDS solutions.8)

10

7

10

6

10

5

10

4

0

2000

4000

6000

8000

10000

Frequency (kHz)Fig. 1 The calculated frequency spectra of
the acoustic cavitation noise without (above) andwith (below) the temporal fluctuation of the numberof bubbles.

Conclusion

Numerical simulations of acoustic cavitationnoise have revealed that the white noise could be
generated by the temporal fluctuation of the numberof bubbles. The intensity of the white noise
increases as the acoustic amplitude, the number of
bubbles, and the amplitude of the temporalvariation of the number of bubbles increase.
References
1.
T.J.Matula,
I.M.Hallaj,
R.O.Cleveland,
L.A.Crum,
W.C.Moss,
and
R.A.Roy,
J.Acoust.Soc.Am. 103 (1998) 1377.
2.
P.-K.Choi,
Y.Kaneko,andT.Meguro,
Jpn.J.Appl.Phys. 47 (2008) 4111.
3. E.A.Neppiras, Phys.Rep. 61 (1980) 159.
4. V.I.Ilyichev, V.L.Koretz, and N.P.Melnikov,
Ultrasonics 27 (1989) 357.
5. M.Ashokkumar, M.Hodnett, B.Zeqiri, F.Grieser,
and G.Price, J.Am.Chem.Soc. 129 (2007) 2250.
6. S.Luther, M.Sushchik, U.Parlitz, I.Akhatov, andW.Lauterborn, in Nonlinear Acoustics at theTurn of the Millennium: ISNA15, edited by
W.Lauterborn and T.Kurz, AIP Conf.Proc.No.
524 (AIP, New York, 2000), p.355.
7. K.Yasui, Y.Iida, T.Tuziuti, T.Kozuka, andA.Towata, Phys.Rev.E 77 (2008) 016609.
8. J.Lee, M.Ashokkumar, S.Kentish, and F.Grieser,
J.Am.Chem.Soc. 127 (2005) 16810.

2P6-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 263- 264
11-13 November, 2008

Dependence of Sonochemiluminescence on Pulsed-wave
Conditions at 1 MHz
１ＭＨz ソノケミルミネセンスのパルス波依存性
Ayako Ozawa †and Pak-Kon Choi (Dept. of Phys., Meiji Univ.)
小澤綾子‡，崔博坤 （明大理工）

1. Introduction
Pulsed or tone-burst ultrasound is widely used in
medical diagnosis and in the study of various
effects of cavitation. Previous study have shownthat cavitation by pulsed ultrasound can beenhanced by an appropriate choice of pulse lengthand pulse repetition frequency. [1-3] In this paper,
we report the enhancement of multibubble
sonochemiluminescence (SCL) intensity in luminol
solution using pulsed ultrasound at 987 kHz. The
intensity of SCL from luminol solution is larger by
two orders of magnitude than that of thesonoluminescence (SL).
The SCL intensity
depends on the gas content, and few studies havebeen done on the dependence on the gas content.
We have measured sonochemiluminescence (SCL)
from luminol solution with various gas contents andvarious pulse conditions.
2. Experiments
Luminol solutions, air-saturated and degassed to30%, 50%, 70% of saturation, were irradiated in arectangular quartz cell of 200 mm in length, 130
mm in width, and 150 mm in height.
A
piezoceramic transducer was bonded to the bottomof the cell. Pulsed ultrasound at 987 kHz withvarious duty ratios was excited by using a function
generator and a power amplifier. The number ofpulse-on cycles was fixed to 50, 500, and 5000, andthe duty ratio was changed in the range from 0.1 to100.
The duty ratio is defined as pulse-off cycles
divided by pulse-on cycles, and is represented by“D” hereafter.
SCL was measured with aphotomultiplier cooled to -20℃, and the signal
was monitored with a photon counting system. The
SCL signal was detected over 20 seconds, andaveraged to obtain the SCL intensity per a finite
duration time. The electric input power was in therange from 19 to 121W for continuous wave.
3. Results and discussion

Figure 1 shows the results of SCL measurements
for the degree of air saturation of 50 % as a typicalcase. The SCL intensity relative to that for

Fig.1. Relative SCL intensity as a function of duty
ratio (= off cycle number/on cycle number) for (a)on-cycles=50, (b) on-cycles=500, and (c)on-cycles= 5000.

continuous wave was plotted as a function of duty
ratio.
Figure 1 (a), (b), and (c) represents theresults for pulse on-cycles of 50, 500 and 500,
respectively. For the case of on-cycles=50, therelative intensity is 1-2 up to the duty ratio D=10
and decreases over D =10. For the cases of
on-cycles=50 and 500, the maximum relative
intensity is 5.6 at D=10 and 17 at D=20,
respectively, and D value at the peak increases asincreasing
on-cycles.
Ultrasonicpower
dependence is monotonous for on-cycles=50, andcomplicated for other cases.
The results for other degrees of air saturation
exhibited a similar tendency to have intensity
maxima but with different peak values at different
D values. Figure 2 summarizes the peak value ofthe relative SCL intensity at D =20 for each case of
on-cycles. The relative SCL intensity takes amaximum at the degree of about 50 %.

Fig. 2. Maximum relative SCL intensity vs.
degree of air saturation for the cases of on-cycles= 50, 500 and 5000.

Fig.3. Time sequence of pulse-on andpulse-off times.
Enhancement by pulsed waves have been
explained by Flynn and Church [4]. There is asize distribution of bubble nuclei that can grow intotransient cavities at a given frequency and acousticpressure. Only nuclei in a much narrower range ofthis size distribution grow into transient cavities

that contribute to the cavitation activity. The
bubbles of initial size in the range of 0.1 – 4 μm
show large expansion ratio of Rm/R0 at 7.5 atm and1 MHz. Here Rm and R0 indicates maximum andinitial radius, respectively. During pulse-off time
bubbles shrink via gas diffusion into liquid. If the
bubble sizes are in this range at the time of t1,
indicated in Fig.3, they can contribute to thecavitation activity in the next pulse-on time. Large
expanded bubbles fragment to generate manydaughter bubbles which contribute to theenhancement of SCL.
In Figs. 1 (a), (b), (c), the SCL intensity
decreases at large D value where bubble radius may
decrease below the critical value of the efficient
radius range. Here we assume that the value of D=100 corresponds to the critical radius of 0.1 μm.
Pulse off times (T0ff) calculated from D =100 are (a)5 ms, (b) 50 ms, (c) 500 ms in the three cases.
We can roughly estimate the bubble size (Rx) at t0
based on the calculation of Epstein and Plesset [5].
A bubble of radius Rx at t0 shrinks to the criticalvalue during the time Toff. They obtained the valueof about 2 s for a bubble of 10 μm for complete
dissolving in the case of gas saturation degree of
50 %.
Since this time of dissolution is
proportional to the square of the initial radius, we
can obtain the values of 0.5, 1.5, and 5 μm as Rx.
This suggests that larger pulse-on time makes alarger bubble size at the end of the pulse-on time.
This may resulted by bubble coalescence in longpulse-on time.
The experimental results in the case ofsaturation degree of 100 % showed thatenhancement was observed only at on-cycles= 5000
and low acoustic power.
In case of thesaturation degree of 30 %, enhancement wasobserved only at on-cycles= 50 and SCL intensity
almost vanishes at D= 10. Bubbles do not growcompared to the higher saturation degree because ofless rectified diffusion of gas.
References
1. T. G. Leighton, “The acoustic bubble” Academic,
1994, p.504.
2. P. Ciuti, N. V. Dezhkunov, G. Iernetti and A. I.
Kulak, Ultrasonics, 36(1998)569.
3. P.- K. Choi, Y. Kaneko and T. Meguro, Jpn. J.
Appl. Phys. 47(2008)4111.
4. H. G. Flynn and C. C. Church, J. Acoust. Soc.
Am.76 (1984)505.
5. P. S. Epstein and M. S. Plesset, J. Chem. Phys. 18(1950)1505.

2P6-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 265- 266
11-13 November, 2008

Spatio-Temporal Separation of Na-atom Emission
and Continuum in Sonoluminescence
ソノルミネセンスにおける Na 発光と連続スペクトル成分の時間空間分離
Pak-Kon Choi and Shogo Abe (Dept. of Physics, Meiji University)崔 博坤， 阿部将吾 （明大理工）

1. Introduction
Multi-bubble sonoluminescence (MBSL)
spectrum from NaCl solutions consists of acontinuum extending into the UV region andasymmetrically-broadened lines of sodium
atoms [1-3]. The origin of the continuum
emission is suggested to be bremsstrahlung or
blackbody radiation or excited-state molecularemission. We measured the SL spectra of
sodium atom emission from ethanol-doped
NaCl solutions [4] and showed the quenching
and broadening of the Na line upon adding
ethanol, which suggested that the sodium atomemission occurs in the gas phase insidebubbles.
In single-bubble SL from NaCl solutions,only the continuum was obtained and thesodium atom emission was not observed [5].
The difference in the results by MBSL and
SBSL brings a question that the continuum andsodium atom emission occur in the same bubble
or different bubbles.
We report here aspatio-temporal separation of the sodium atomemission and continuum in MBSL fromargon-saturated NaCl solutions.

continuous signal of 138 kHz was amplified bya power amplifier (NF Circuit Design,
HAS4014) and impedance matched by atransformer. Applied voltage to the transducer
was 10 – 40 Vpp.
For temporal separation of the continuumand Na emission, we measured the SL pulse
spectrally isolated. SL was divided into two
spectral components above 500 nm and below
500 nm by using dichroic mirror. Eachcomponent
was
detected
withtwophotomultipliers and displayed with a fastsampling oscilloscope (4 GS/s, Agilent
DSO5052A) at the same timing as ultrasoundperiod.
3. Results and discussion
Figure 1(a) shows the photograph of SL (fullcolored in the web version) viewed from the(a)2. Experiment
We took photographs of MBSL from 2M
NaCl aqueous solution using a digital camera(Nikon D70S).
The Red-Green-Bluecomponents of the photographs were digitally
splitted using a “Image J” software for spatial
separation of the continuum and Na emission.
The blue component is assumed to becorresponding to the continuum and the redcomponent to the Na emission at 590 nm.
The solution was contained in a cylindricalglass cell with 80 mm in diameter and 120 mm
in height.
A sandwiched transducer wasbonded to the bottom of the cell.
A

(b)

(c)

Fig.1 (a): Photograph of sonoluminescence from
NaCl solutions at the voltage of 20 Vpp. Red
component (b), and blue component (c) of thephoto (a).

cylindrical side of the cell at an applied voltage
of 20 Vpp. Both orange-colored region andwhite region are seen in the photograph. At
lower voltage only orange-colored SL appearednear the center axis of the cylindrical cell. Theorange-colored region expands outward as theapplied voltage increases. Red and blue
components of the Fig. 1(a) are digitallyprocessed by a software and illustrated in Figs.
1(b) and 1(c), respectively.
The redcomponent corresponding to the Na emission
spreads over a wide region compared with theblue component which corresponding to thecontinuum.
The regions which emit
continuum are near the bottom of the cell andbelow the surface of the solution. Sound
pressure is probably high in these regions. At
higher applied voltages the ‘continuum region’
expands and shows a similar distribution as thatin Fig. 1(b). These results indicate that the Na
emission originates from bubbles which
undergo lower pressure and the continuum
originates from bubbles which undergo higher
pressure. In other words, the Na emission
comes from lower-temperature bubbles and thecontinuum from higher-temperature bubbles.
The results of the temporal measurement ofSL pulse are shown in Fig. 2. Upper and lower
oscilloscope tracings are corresponding to the
Na emission and continuum emission,respectively. The SL pulses were triggered byultrasound period and were stored about 1 s.
SL in Figs. 2(a), 2(b) and 2(c) were obtained atapplied voltages of 16.5, 23.5, and 35 Vpp,
respectively.
In Fig. 2(a), only the Na
emission pulse was obtained, which agrees
with the results of spatial measurement. At
higher voltage as shown in Fig. 2(b), SL pulses
are almost synchronous with ultrasound period
and the timing of SL pulse emission has a wide
distribution. The timing of the Na emission
shows a wider distribution than that of thecontinuum emission. The distribution of theSL pulse results from a distribution of bubble
radius. Then the results suggest that the Na
emission originates from bubbles which have a

(a)

(b)

(c)

Fig.2. Oscilloscope tracings of SL pulses.
Upper: Na emission. Lower: Continuum
emission. Applied voltage are (a)16.5 Vpp,(b) 23.5 Vpp, and (c) 35 Vpp.

wider distribution of radius. In Fig. 2(c), theNa emission pulse shows chaotic behavior
while the continuum emission pulse remains asynchronous property.
It is concluded that bubbles which cause
Na emission have large radii with a wide
distribution. The peak temperature in suchbubbles is relatively low compared withbubbles which emit the continuum.
References
1. C. Sehgal, R. P. Steer, R. G. Sutherland and R. E.
Verrall, J. Chem. Phys. 70, 2242-2248 (1979).
2. E. B. Flint and K. S. Suslick, J. Phys. Chem. 95,
1484-1488 (1991).
3. F. Lepoint-Mullie, N. Voglet, T. Lepoint and R.
Avni, Ultrason. Sonochem. 8, 151-158 (2001).
4. P.-K. Choi, S. Abe and Y. Hayashi, J. Phys.
Chem. B 112, 918-922 (2008).
5.

T. J. Matula, et al., Phys. Rev. Lett. 75, 2602-2605 (1995).

2P6-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 267- 268
11-13 November, 2008

Influence of the secondary acoustic radiation from abubble on the vibration phase of the other bubble
気泡の二次的な音響放射が他気泡の振動位相に与える影響
Takaaki Fujikawa1‡ Kenji Yoshida2 and Yoshiaki Watanabe2(1Facul. Eng., Doshisha Univ.; 2Facul. Life & Medi. Sci., Doshisha Univ.)
藤川貴彬 1‡，吉田憲司 2，渡辺好章 2（1 同志社大 工; 2 同志社大 生命医科）

1. Introduction
Various ultrasonic techniques using bubbles
have been developed in recent years.
It isnecessary to clarify the bubble dynamics for thedevelopments of these techniques. In the previous
researches, the dynamics of a single bubble has
been investigated experimentally and theoretically.
However the dynamics of multiple bubbles is still
unknown in detail.
In acoustic field, a bubble vibrates
synchronizing with a surrounding pressure variation.
The vibrating bubble shows the secondary acoustic
radiation. When the two bubbles are located inclosely, the secondary acoustic radiation influences
the phase and the amplitude of the vibration ofother bubble. [1] In this study, we try to clarify
the effect of the secondary acoustic radiation on the
bubble vibration. We optically observed the
behavior of two bubbles, focusing on the interactive
force between two bubbles. Based on the analysisof the direction of the interactive force, weinvestigate the influence of the secondary acoustic
radiation on the bubble vibration phase.
2. Theory of the interactive force
The interactive force called the secondary
Bjerknes force acts between two vibrating bubbles.
The direction of the interactive force is determinedby the relation of vibration phases of bubbles. In
this section, we explain the interactive force
between two bubbles.
2.1 The Secondary Bjerknes force
Two bubbles of bubble 1 and bubble 2
linearly vibrate in phase φ1 and φ2. In this case,the interactive force acting between two bubbles isrepresented as
3

3

2πρR10 R20 ω 2〈F〉 = −
ε 10ε 20 cos (ϕ1 − ϕ 2 ),D2

(1)

where < > is the time integration for one driving
ultrasound wave cycle, ρ is density of liquid, R10
and R20 are the equilibrium radii of the bubbles, ε10-----------------------------------------------------------dth0106@mail4.doshisha.ac.jp

and ε20 are the vibration amplitudes of the bubbles,ω is the angular frequency of an external sound, andD is the distance between the centers of the
bubbles.
In the Equation (1), we can understand thatthe direction of F is decided by vibration phasedifference “φ1-φ2”.
2.2 Vibration phase difference “φ1-φ2”
Assuming that there is no influence of
secondary acoustic radiation from the bubble on theother bubble vibration, φ1 and φ2 are determined
only by ω, R10 and R20．[2] We explain the phase φin detail. In the case of “R0 > Rr”, φ equals 0, andin the other case of “R0 < Rr”, φ equals π. [2] Rr is
the resonance radius of a free bubble. When boththe initial radii R10 and R20 are larger than Rr or
smaller than Rr, φ1-φ2 equals 0. As the results, theattractive force acts between two bubbles. When
R10 (or R20) is larger than Rr and R20 (or R10) is
smaller than Rr, the repulsive force acts since φ1-φ2equals π. It should be noted that the direction of F
doesn’t depend on D when the secondary acoustic
sradiation doesn't influence the bubble vibration.
Considering this influence of the secondary
acoustic radiation from the bubble, “φ1-φ2” isrepresented as

ϕ1 − ϕ 2 = tan −1

B1
B− tan −1 2 .
A1
A2

(2)

The detailed equation is described in Ref. [1]. In
the Equation (2), A and B are the functions of D, R10,
R20, and ω. Therefore, “φ1-φ2” is determined bythose parameters. It should be noted that thedirection of F depends on D in addition to R10, R20,and ω. Examining the dependence of the directionof interactive force on D, therefore, we caninvestigate the effect of the secondary acoustic
radiation on phase difference between bubbles
vibrations.
3. Observation procedure
Focusing on the direction of interactive force
between two bubbles, we observed the behaviors of
two bubbles using a high-speed video camera.
The observation system is described in Ref. [3].

Positive electrode

Side view

Negative electrodepolymer film
Adhesion bubble

BubbleOxygen bubble
ElectrodeLangevin transducer

Fig.1 Experimental cell.
4.

Observation result and discussion

4.1 Influence of the secondary acoustic radiation
We observed the bubble behavior in several
conditions for D. Ra0 is lager than Rr, and Rf0 issmaller than Rr. Rf0 is initial oxygen bubble radius.
Figure 2 shows the observation results of the
bubble behaviors. In this condition, the repulsive
force should act between the bubbles, assuming that
there is no influence of the secondary acoustic
radiation on the bubble vibration. Figures 2 (a-1)
and (b-1) show the observed images before
irradiating the ultrasound; also Fig.2 (a-2) and (b-2)
are the observed images during the ultrasoundirradiation. In Fig.2 (a), (b), D are 690µm and445µm respectively. The irradiated ultrasoundpressure at the bubble position is 3kPa. From theseries of Fig.2 (a), we can confirm that the repulsive
force acted between these bubbles. Contrary to
our expectation, we can see that the attractive force
acted between these bubbles in Fig.2 (b). As theseresults, it is clearly demonstrated that the directionof F depends on D. In other words, the secondary
acoustic radiation influences the bubble vibration.
Oxygen bubble

a-1

Adhesion
bubbleOxygen bubble

Adhesionb-1 bubble
Initialposition

Initialpositionb-2

a-2
200 µm200 µm

Fig.2 Interactive force between two bubbles.

4.2 Qualitative discussion
Dependence of the direction of F on D was
observed only in specific condition for bubble size.
We observed bubble behavior in various D and Ra0.
Ra0 is initial adhesion bubble radius.
Figure 3 shows the experimental result.
The white circle plots show the attractive force, theblack circle plots show the repulsive force, the graysquare plots show the direction of F was unknown,
and the dashed line shows the condition for contactof the two bubbles.
In Fig.3, the experimental result shows thatthe attractive force acts in Ra0 < 100µm. The
repulsive force acts in Ra0 > 140µm. On the other
hand, these results show that the direction of theinteractive forces depend on D in the range of Ra0
from 100µm to 140 µm. We discuss why thedependence of direction of F on D appears inspecific radial conditions. In R0=Rr, pressure
amplitude of acoustic wave radiated by a bubble issignificantly large. In this experimental condition,
Rr is 100µm. Therefore, we supposed that thedependence of direction of F on D appears whenRa0 is near the resonant condition.
Distance
between Distance
two bubbles;
D [µm][µm]

Figure 1 shows the structure of theexperimental cell. The electronic signal is input tothe transducer bonded to the acrylic cylindricalcontainer. In this cell, the standing wave is formed.
The bubble is adhered to polymer film at theantinode of the standing wave.
Below theadhesion bubble, an oxygen bubble is generated byelectrolytes of water. In this experiment, thedirection of the interactive force is decided by the
movement of the oxygen bubble.

1000

Attractive force
Repulsive force
Unknown

800
600
400
200
0
50

100

150

200

Radhbubble
radius radius;[µm] Ra0 [µm]Initial adhesion

Fig.3 Direction of interactive force in Ra0- D plane.
5. Conclusion
In this paper, we optically observed the
behavior of two bubbles using a high-speed video
camera, focusing on the direction of the interactive
force between two bubbles. As the results, it was
confirmed that the direction of the interactive force
depends on the distance between two bubbles.
Therefore, it was verified that the acoustic wave
radiated by the bubble effect on the vibration phaseof the other bubble.
References
1. Masato Ida, Phys.Rev.E, 67, 056617, 2003.
2. T.G.Leighton, “The Acoustic Bubble”,
ACADEMIC PRESS, 1994.
3. K. Yoshida et al. : Jpn. J. Appl. Phys. 47 (2008)
4200.

2P6-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 269- 270
11-13 November, 2008

Collapsing behaviors of two bubbles adhered to therigid wall in an ultrasonic field: Simultaneous
generation of micro flows
超音波場における二つの壁面付着気泡の崩壊挙動：同時発生す
る複数の微小流Kenji Yoshida1†and Yoshiaki Watanabe1(1 Facul. Life & Med. Sci., Doshisha Univ.)
吉田憲司 1‡，渡辺好章 1（1 同志社大 生命医科）

1. Introduction
In ultrasonic cleaning technique andsonoporation which is gene thrapy technique using
ultrasound, cleaning effects and gene introduction
are considered to be enhanced by effects of bubbles
driven by ultrasound. In case of a bubble near arigid material or tissue in an acoustic field, thebubble typically shows a “non-spherical vibration”
which is induced due to effects of the material near
the bubble.
Since the dynamics of thisnon-spherical vibration have been still unknown,
further detailed understanding should be necessary.
In previous studies on a collapse of a single bubble
adhered to a rigid material or soft gel, detailed
bubble behaviors and its dependence on bubble size
have been examined. [1,2] However, there are few
reports on behaviors of multi bubbles near amaterial. In the case of multi bubble, interactive
force acting among bubbles which is called
secondary Bjerkens
force should induce
non-spherical vibration in addition to the effects ofa material near bubbles.
In order to examine effects of interaction on
non-spherical vibration of bubbles near a rigidmaterial, we observed behaviors of two bubbles
adhered to a quartz glass, using a high-speed video
camera with maximum recording rate 106 fps. As
results, we confirmed that non-spherical vibrationsof two bubbles are different from that of single
bubble. In particular, interesting bubble behaviors
such as a simultaneous generation of several microflows are observed. In this paper, we discusse
effects of interaction between two bubbles onbubble behaviors.

bolted Lagevine transducer was attached to thebottom of an acrylic cylindrical cell with a diameterof 60mm. A quartz glass with a height of 10mm, awidth of 10mm and a thickness 2mm was inserted
in the cell. Then, two bubbles are adhered to thesurface of the quartz glass. The initial radii Ro of
bubbles are from 70 to 450 m. The initial
distance L between two bubbles is from 0 to 650 m.
Here, L is defined as the distance from a center of abubble to that of the other bubble. The bubble
behaviors were observed from top or side face of
bubbles under an irradiation of ultrasound withcenter frequency 27 kHz and maximum soundpressure 100 kPa.
Quartz
glass

Top
view

Cylindrical Cell
(diameter 60mm)

Side
view

Transducer(diameter 45mm)

Fig.1 Observation cell.
3. Results

When normalized initial distance between
two bubbles L/(R1o+R2o) were shorter than 1.5,
observed results demonstrated that collapse
behaviors of two bubbles were far different fromthat of a single bubble. Focusing on “process of
bubble deformation” and “generation of micro
flow”, the differences are discussed.

2. Experiment system

3.1 Process of bubble deformation

We observed bubble behaviors using
high-speed video camera (Shimadzu HPV-1). The
detailed system for observation was described in
Ref [1,2]. Figure 1 shows the arrangement of two
bubbles and quartz glass in observation cell. A

In case of a single bubble, previous researchshowed that the bubble kept axial symmetry shapeuntil the split though it vibrated non-spherically.[1]Here, the axis of symmetry is perpendicular to therigid surface through the center of the bubble. Incase of two bubbles, we observed that bubbles lost
axis symmetric shape until the split of bubbles.
This is probably because attractive or repulsive
force caused by interaction between bubbles affects
the bubble deformation.
Figure 2(a),(b) show observed results.
Bubble behaviors were observed from side face of
bubbles. The observed times of obtained pictures
are displayed on each picture. The input time ofan electrical signal to the transducer is 0sec. In
Fig.2 (a), we confirmed that the top portion of eachbubble moved toward the other bubble. Then, thesurface of each bubble opposite to the other bubble
was fluctuated. This deformation process clearly
indicated that the attractive force acted between
bubbles. In Fig.2 (b), we could confirm that two
bubbles lost the axis symmetric shape.
Thesmaller bubble showed violent non-sphericalvibration and moved away from the larger bubble.
The Larger bubble showed the surface fluctuation
which appeared only in the portion near the smaller
bubble.
The movement of smaller bubble
indicates that the repulsive force acted between
bubbles. Therefore, we suppose that bubbles lostaxial symmetric shape due to the repulsive force.

4. Conclusions

In order to examine effects of interaction on
behaviors of bubbles near a rigid material, weobserved behaviors of two bubbles adhered to aquartz glass, using a high-speed video camera.
When two bubbles were significantly near, it was
indicated that the interaction between bubbles
significantly affected “process of bubble
deformation” and “generations of micro flows”.

(a) 0 sec

Figure 2 demonstrates an observed result of thesimultaneous generation of several micro flows.
Bubble behaviors were observed from the top faceof bubbles. After ultrasound irradiation, smaller
bubble showed violent non-spherical vibration.
On the other hand, the larger bubble almost did notvibrate.
Then, a micro flow seemed to begenerated into the smaller bubble [see picture (a)].
After the generation of this flow, the surface oflarger bubble near smaller one expanded locally[see picture (b)]. When this local expanded
portion contracted, a micro flow generated into thelarger bubble [see picture (c)]. This local surface
fluctuation propagated on the larger bubble surface.
Then several micro flows simultaneously generated
into larger bubble [see picture (d)].

(c) 340 s

Force

Surfacefluctuation

12(a) Under action of attractive force.
(a) 0 sec

1(b)150 s(c) 226 s

Force

Surfacefluctuation

2(b) Under action of Repulsive force.

3.2 Micro-flows generations

We observed specific generations of microflows which followed above-mentioned fluctuationof bubble surface induced by interaction.
Sometimes, we clearly confirmed simultaneous
generation of several micro flows. This microflows were generated in the direction parallel oroblique to the surface of quartz glass. In case of asingle bubble, a micro flow was generated in the
direction normal to rigid surface.[1](b) 268 s

Fig.2 Deformation induced by interaction. (a)R1o and R2o are 212 m and 243 m respectively.
L/( R1o + R2o) is. (b) R1o and R2o are 97 m and281 m respectively. L/( R1o + R2o) is .
(a) 194 s(b) 238 s
1
Local
expansion2Flow(c) 274 s(d) 402 s

Flow

Flows

Fig.4 Several micro-flows generation. R1o andR2o are 338 m and 110 m respectively. L/( R1o +R2o) is.

References
1. S.Nakatani et al.: Jpn. J. Appl. Phys. 47 (2008)
3904.
2. K. Yoshida et al,: Jpn. J. Appl. Phys. 47 (2008)
4200

2P6-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 271- 272
11-13 November, 2008

FEM
AnalysisofPiezoelectricResonance
Characteristics on the Geometrical Configuration of a
Sonochemical Reactor
ソノケミカル反応容器の音場設計における圧電共振特性のFEM 解析
Nagaya Okada1†, Masanori Sato1 and Yoshiyuki Asakura1 (1 HONDA ELECTRONICS
CO., LTD.)岡田長也 1†，佐藤正典 1，朝倉義幸 1 （1 本多電子）

1. Introduction
Recently, chemical effects and physicaleffects caused by ultrasonic cavitation have beenstudied widely. The physical factors for the reaction
field have been elucidated by many researchers,
clarifying the relationship of chemical action to theshape of the sonochemical reactor, the shape andplacement of the transducer, etc. However noinvestigation has been focused on measuring
ultrasonic energy distribution for the industrial scale
sonochemical reactors.
In order to have an industrial application ofsonochemical action, the important factors that
affect cavitaiton include ultrasonic frequency,
acoustic power, ambient temperature, ambientpressure, and so on. Many researchers haveinvestigated the frequencies ranging from 20 to1200 kHz. It was widely noted that thesonochemical reaction efficiency was improved at ahigh frequency region from several 100 kHz. In
these experiments, the irradiation volume ranged
from 10 to 500 ml. Asakura et al. examined asonochemical efficiency for a frequency of 45 kHz
was improved using cylindrical sonochemical
reactor in 70 mm diameter at a liquid height of 500
mm [1]. This result suggests that precise condition
setting of sonochemical field may improve
sonochemical efficiency value even at a low
frequency. At the low frequency region, thedistribution of ultrasonic energy attributed by input
acoustic power especially can be changed
significantly according to the size and shape of thesonoreactors as well as the height of the water.
Hence the degree of chemical and mechanicaleffects in each position becomes an obstruction to a
precise control.
This study presents an impedance of atransducer dependence on the geometricalconfiguration of a sonochemical reactor cell. The
impedance of the transducer changed significantly
when the standing wave field was resonant [2]. The
sound field was generated under several-----------------------------------------------------------E-mail: nagaya@honda-el.co.jp †configurations of sound sources and reflectors. The
dependence between the impedance of thetransducer and the sound pressure distribution in thesonochemical reactor was calculated by using the
Finite Element Method (FEM). A sound pressure
field was calculated when a few pressure antinodes
exist in a sonochemical reactor cell using the most
simplified case.
2. Simulation model
In the present study, the commercial available
FEM software has been utilized (ANSYS, ANSIS
Inc.). In the software, the sound field analysis andpiezoelectric transducer analysis can be calculated
at a same time.
The calculations have been performed for arectangular cell of 56 mm x 56 mm x 100 mm ininternal dimensions and a cylindrical cell with 56
mm in diameter filled with water at 20 ºC. A
bolt-clamped Langevin type transducer (BLTtransducer) with a diameter of 45 mm was attachedto the bottom of the cells. From the symmetry of thecylindrical cell, a 2-D plane mode has been
considered in the calculation. For the rectangularreactor, 1/4 of the total 3-D volume model has been
considered. As a boundary condition, the appliedpressure is assumed as 0 at the inner surface ofreactor’s wall and the liquid surface. The frequencyof the BLT transducer and the liquid height werechosen on setting of processing conditions to exist a
few sound pressure antinodes. The impedance of
the BLT transducer was evaluated as a function of
the liquid height.
2. Results and discussion
The calculated spatial distribution of thepressure amplitude is shown as a function of theliquid height in Fig.1. The BLT thickness was
decided as the frequency was 25 kHz at the liquidheight of 70 mm. The calculation was worked out
by maintaining this BLT thickness, thus the driving
frequency of 25 kHz. In Fig.1, the calculated
picture shows only a half of the 2-D plane mode,

and the right side of the picture is the reactor’s wall.
A striped pattern shows a sound pressure
antinodes’s existence. The pressure amplitude fieldat the liquid height of 80 mm is the most stable, andthe field is disturbed depending on changes inliquid height.
Figure 2 shows the resonant frequency andthe impedance of the BLT transducer as a functionof the liquid height. The resonant frequency
decreases as a liquid height increases and theimpedance at the liquid height of 80 mm is changed
abruptly. This result suggests the degree of theresonant in the cell can be read the change by thechange of the impedance.

cente
r

wall

65 mm

65 mm

wall

65 mm
70 mm
90 mm
97 mm
Fig. 3 Calculated spatial distribution of the pressure
amplitude. The liquid height of 80 mm and 97 mm are
better stable on sound pressure field.

25

20-10000000

50

Resonant Frequency (kHz)

Impedance (a. u.)

30

60

70

80

90

100

110

40
Impedance (a. u.)

65 mm
75 mm
80 mm
90 mm
Fig. 1 Calculated spatial distribution of the pressure
amplitude. The liquid height of 80 mm is the moststable on sound pressure field.

3530-5. 00E+06

50

Resonant Frequency (kHz)

cente
r

is changed. However, not all the data explain thisphenomenon. The impedance value is changed
abruptly at the liquid height of 100 mm because theimpedance value is strongly affected by theresonant frequency changing. The gradient ofresonant frequency curve is not constant at thisliquid height and it makes more difficult todetermine of the best state.

70

90

110

130

Liquid Height (mm)Fig. 4 Dependence of the liquid height on calculated
resonant frequency and impedance of the BLTtransducer driving at 34 kHz.

Liquid Height (mm)3. Conclusion
Fig. 2 Dependence of the liquid height on calculated
resonant frequency and impedance of the BLTtransducer driving at 25 kHz.

In Fig.3, the calculated result for the case at
driving frequency of 34 kHz is shown. The soundpressure antinodes increase on the liquid heightincreasing. The pressure field at the liquid height of
70 mm and 97 mm is more stable than the liquidheight at 65 mm and 90 mm, respectively. The
resonant frequency and the impedance are shown in
Fig.4. The calculated result indicates that the
impedance is changed when the degree of resonant

The impedance of the transducer dependence
on the sound pressure field condition was evaluatedusing the FEM method. The results suggest that thedegree of the resonant in the cell can be read thechange by the change of the impedance. It must be
helped very much to understand the optimal designof the sonochemical reactor cell.
References
1. Y. Asakura, T. Nishida, T. Matsuoka, S. Koda:
Ultrason. Sonochem.15 (2008) 244.
2. Y. Asakura and S. Koda: Ultrasonic Technology 5(2007) 55 [in Japanese].

2P6-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 273- 274
11-13 November, 2008

The Intensity of MBSL in Aqueous Solutions at 2.4 MHz
超音波霧化中の多泡性ソノルミネッセンス
Hisashi Harada†, Naohiro Iwata and Keisuke Shiratori (Facult. Sci. Eng., Meisei Univ.)
原田久志‡，岩田尚大，白鳥啓介 （明星大 理工）

It is known that the high frequency
oscillator (> 1 MHz) provides liquid mist. Thiseffect has received much attention for the
possibility of practical use. Former paper, we
confirmed the illumination originates fromcavitation during ultrasonic irradiation at 2.4 kHz[1]. In recent years, we have reported relation
between the intensity of MBSL (multi bubble
sonoluminescence) and sonochemical reactivity at
200 kHz [2]. In this presentation, the relation will
be discussed in high frequency region.
2. Experimental
A Pyrex glass cylindrical tube (volume about
60 ml, diameter 22 mm, length 300 mm) containing
saturated gases in pure water (5 ~ 20 ml) was used
for experiment. As dissolved gases, Ar, O2, N2, H2,
He, air and the mixtures of O2 and N2 were prepared.
Each gas was passed through the solution except
the air-saturated sample before irradiation. The
composition of dissolved gas in the solution at theinitial stage of observation was thought similar
composition of atmospheric gas in the reactor. The
atmospheric gas was analysed by a gas
chromatography (Shimadzu, GC8AT). Then,ultrasonic waves were applied from the bottom of
the tube attached with ultrasonic atomizer (Honda
Electric, HM-303N, 2.4 MHz, DC 24 V / 1.0 A).

Intensity of sonoluminescence wasmeasured in the dark box attached with photon
counting head (Hamamatsu Photonics, H7360-01)
as shown in Fig. 1. Ultrasonic power was estimatedby KI method and the rate of rising temperature ofsolution in the early stage of ultrasonic irradiation(A Standard Method to Calibrate Sonochemical
Efficiency of an Individual Reaction Systemrecommended by Japan Society of Sonochemistry)[3].
3. Results and discussion

It is known that the intensity of MBSL
decreases with increasing frequency [4]. However,
MBSL was detected in an air atmosphere even at
2.4 MHz. Fig. 2 indicates the effect of volume ofwater in the tube on the intensity of MBSL. Clear
result was obtained. According to this result,volume of 10 ml of solution was adopted for below
examinations.
5ml

300
Intensity / a.u.

1. Introduction

10ml

20ml

200

100

Pyrex glass cylinder
300mm

Liquid surface

0
0

1
2
Sonication time / sec

3

Fig. 2 Effect of volume of water on MBSL
10mL
= 47mmPhotomultiplier(H7360-02),
300〜650nm, φ= 22mm
Ultrasonic oscillator (HM-303N),
2.4MHz, DC24V / 1.0A , φ= 20mm

Fig. 1 Experimental setup for measurementof sonoluminescence-------------------------------------------------------------E-mail address: harada@chem.meisei-u.ac.jp

Fig. 3 illustrated time dependencies of theintensities of MBSL in various kinds of dissolved
gases. The selection of dissolved gas is importantfor cavitation. Argon was recorded the highest
intensity. The intensity followed the order of Ar >Air > O2 > N2 >> He, H2, CO2. In the cases of H2and CO2, only a little MBSL was detected. In thisfigure, we note that the intensity of air is higher
than those of each element (O2 and N2). Air
includes about 20%O2. Thus, composition of air isthe gas mixture of 20%O2 - 80%N2 if minor gases
are not considered. In order to confirm the mixed
gas effect, MBSL was measured in various ratio of
O2 - N2 mixture.

showing experimental section. Therefore, it wascertain that not only sonoluminescence but
also chemical power was gained even at 2.4
MHz.

2 0 00
Ar
Air
O2
N2
He
CO2
H2

1 5 001 0 00

5 00

Photon n umbe r / Coun ts･10 0 ms -1

Ph oton n umber / (10 - 1 ms) -1

2 5 002 5 00 00 0
2 0 00 00 0
1 5 00 00 0

OFF

50 0 00 0001
2
Son ic ation time / Se c

UltrasoundON
1 0 00 00 000

Ultrasound

50

10 0
1 50
20 0
Measu ring time / Se c

25 0

30 0

Luminol + K3Fe(CN)6 in NaOH solution

3

Fig. 5 Measurement of chemical power

SL In ten sity / a.u .

Fig. 3 Effect of dissolved gas on MBSL

SL i n t e n si t y / a. u .

8000

6000
Si mi l a r to A i r

4000

600
400
200
0

2000

0

5

10

15

20

Conce ntration of C 2 H 5 OH / %
0
0

20

40

60

80

100

O 2 c o n c e n t r at i o n / %Fig. 4 Mixture gas effect on MBSL
Fig. 4 shows dependence of the intensity of
MBSL on O2 concentration in N2 matrix. The
intensity increased with O2 concentration below
40% O2. The intensity at 20％ O2 was similar tothat in air. The maximum intensity was obtained at
40% O2. This ratio is the similar ratio for air. In theregion above 40% O2, on the other hand, the higher
concentration of O2 was applied, the lower intensity
was observed.

As another examination, sonochemical
luminescence was performed as shown in Fig.
5. Increasing of illumination was observed inluminol alkaline solution. We also confirmed
sonochemical power using by the Standard
Method to Calibrate Sonochemical Efficiency inFig. 6 Addition effect of ethanol on MBSLIn the case of producing liquid mist,
ethanol solution is often utilized. So, we try to use
ethanol in order to obtain MBSL. As shown infigure 6 the intensity was decreasing drastically.
References
1. H. Harada, H. Yoshida and H. Kato, 11th meetingof European Society of Sonochemistry (2008,
France).
2. H. Harada and H. Kato, International Symposium
on sonochemistry and sonoprocessing (2007,
Kyoto)
3. S. Koda, T. Kimura, T. Kondo and H. Mitome,
Ultrasonics-Sonochemistry, 10(3), 149-156(2003)
4. P. Kanthale, M. Ashokkumar, F. Grieser,
Ultrasonics-Sonochemistry,15,
143-150(2008).

2P7a-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 275- 276
11-13 November, 2008

Basic Investigation for Detection of Early Cancer by
Optically Assisted Ultrasonic Velocity Change Imaging
光アシスト超音波速度変化イメージング法による初期癌検出のための基礎的検討
Hiromichi Horinaka†,Syunsuke Kawakami, Satoshi Ishibashi , Tetsuya Matsuyami,
Kenji Wada, and Toshiyuki Matsunaka (Facult. Eng., Osaka Prefecture Univ.)
堀中博道‡，川上俊介，石橋 賢，松山哲也，和田健司，松中敏行（大阪府立大学 工）

1. Introduction
In recent years, applications of nano-particles to
medical diagnosis and treatment have been actively
researched. It is expected that the nano-particles
display the cancer distribution in biological tissue
because they are easy to accumulate to new bloodvessel created by the cancer. However, this method
cannot be applied to detection of the early stage
cancer because the new blood vessel is not
undeveloped. For detection of early cancer, theagent which has an affinity to protein introduced intumor is expected. The difference of sojourn time of
drug in the tumor tissue from that in the normal
tissue is also expected to use for detection of earlycancer.
The fluorescence labeling methods has been
generally used to detect the tumor area in tissue.
However, it cannot give the depth information oftumor distribution. To detect of early cancer, thephoto-acoustic signal from Photofrin for PDT(Photodynamic Therapy) in tissue mimicking layer
was detected.1)
We already proposed the optically assisted
ultrasonic velocity change method and measured
the optical absorption distribution in highly
scattering medium. 2,3) The method has thepossibility to apply to detection of the lightabsorption distribution in depth of biological tissue.
In this study, we apply the optically assisted
ultrasonic velocity change method to detect the
distribution of medicine which accumulates thecancer tissue in order to develop a new method for
detection of early cancer.

of semiconductor lasers which individuallyoscillated at wavelength of 660nm, 813nm and910nm were used as light sources. Moreover, thelight of 512nm from the green laser (SHG of
Nd:YVO4 laser) was guided by using mirrors toilluminate the phantom.
The center frequency of the ultrasonic pulses
was 13MHz. A frame of image consisted of 346
ultrasonic beams. RF echo waveform data measured
by the array transducer were stored and transported
to the personal computor via the signal processing
board. The waveforms of echo pulses of every line
was divided into appropriate areas with the width oftransmitted pulse. The cross-correlation between thecorresponding area of the waveform data measured
before and after light illumination was calculated toobtaine the time difference of the echo pulse shift
induced by light illumination. The temperaturechange image was constructed from the ultrasonicpulse shift. The optical absorption distribution was
estimated from the temperature change image. 3)

2. Experimental set-up
Figure 1 shows the experimental set-up and thephantom. The ultrasonic array transducer transmits
ultrasonic pulses to the phantom through thetransparency standoff. The optical fibers were
mounted closer by the array transducer. Three kinds

3. Experimental results
ICG (Indocyanine Green) has been known as theimaging agent for angiographic examination byusing the near-infrared light. It was reported that
ICG stayed in the tumor tissue for long time. 4) We
apply the optically assisted ultrasonic velocitychange method to detect the distribution of thetumor-localizing drug, ICG, in chicken meat. The

E-mail address: horinaka@pe.osakafu-u.ac.jp

Ultrasonic arraytransducer
Signalprocessing board

Personal computer

Optical fiber

Remodeled ultrasoundequipment

Phantom

Fig.1 Experimental set-up

Ultrasonic
wave

Light

Agar
Agar+ICG
Chicken meat

Optical Absorption (a.u.)phantom structure is shown in Fig. 2 (a). The agar
colored by ICG was inserted into the chicken meat.
The absorption spectrum of the agar colored by
ICG measured by the monochromator was shown in
Fig.2 (b). The absorption peak locates around
800nm.

(a) Phantom structure

500

600

700

800

900

Wavelength (nm)(b) Absorption spectrum of ICG

Fig.2 Phantom structure and optical property of ICG

The normal B-mode images of the phantom wereobtained by using the experimental set-up shown in
Fig.1. Fig.3 (a) shows the normal B-mode image.
The normal B-mode shows boundaries of tissue but
does not show the position of agar colored by ICG.
The ultrasonic velocity change images were
measured by using four lasers with oscillation
wavelength of 532nm, 660nm, 813nm and 910nm.
The light emitted from the optical fiber was
diffused. The irradiance of the light in the phantom
was set to be below 0.5 W/cm2 in consideration of
the skin exposure limit.
Figure 3 (b) shows the ultrasonic velocity change
images obtained under the light of 813nm at
exposure time 15s, 30s and 45s. The grayscale barat the right of this figure shows the temperaturechange corresponding to the velocity change of the

20mm

45mm

(a) Normal B-mode image
Exposure time: 15s

Exposure time: 15s

30s

30s

45s

45s

(b) Ultrasonic velocitychange images (813nm)(c) Ultrasonic velocitychange images (910nm)

2.0 deg.

Fig.3 Normal B-mode image and ultrasonicvelocity images of the phantom

0.5 deg.

ultrasound waves. The ultrasonic velocity change
image shows the distribution of ICG in the chicken
meat.
Figure 3 (c) shows the ultrasonic velocity change
images obtained under the light of 910nm on thesame irradiance of the light as Fig. 3 (b). The
distribution ICG does not appear in Fig.3 (c).
The difference between Fig.3 (b) and (c) isthought to attribute to the spectrum of Fig.2 (b).
The distribution area of objective agent is thought
to be distinguished from those of biologicalmaterials by measuring the dependence of theultrasonic velocity change image on wavelength.
4. Conclusion
The optically assisted ultrasonic velocity change
method was applied to detect the distribution of
medicine which accumulates the cancer tissue inorder to develop a new method for detection ofearly cancer. The phantom was prepared from thechicken meat and the agar colored by ICG which isusually used as fluorescence label. The lightwavelength of 813nm in the absorption band of
ICG was used to illuminate the phantom. The
ultrasonic velocity change image showed the
distribution area of ICG in the chicken meat. The
depth profile of ICG distribution, which cannot be
obtained by fluorescence labeling methods, wasdisplayed. Experimental results showed that the
optically assisted ultrasonic velocity change method
has the potential to detect early cancer.
Acknowledgment
This research was partially supported by the
Nakatani Foundation of Electronic Measuring
Technology Advancement.
References
1. H. Mukoda, S. Sato, H. Ashida and T. Arai：
The Review of Laser Engineering, 32 (2004)
645 (in Japanese)
2. H. Horinaka, T. Matsunaka et al.: Jpn. J. Appl.
Phys, 41 (2002) 3555
3. H. Horinaka, T. Matsunaka et al.：Electronics
Letters, 43 (2007) 1254
4. T. Ohta, Y. Abe, T. Miura and T. Sato：
NIPPON ACTA RADIOLOGIA 2002, 62, 284(in Japanese)

2P7a-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 277- 278
11-13 November, 2008

Small Calculi Detection for Medical Acoustic Imaging
with Correlation between Ultrasonic Echo Signals
医用超音波イメージングにおけるエコー信号間の相関を用いた微小結石検出法
Hirofumi Taki1‡, Tetsuya Matsuda1 and Toru Sato1 (1 Graduate School of Informatics,
Kyoto Univ.)
瀧宏文 1‡，松田哲也 1，佐藤亨 1 （1 京大 情）

1. Introduction
Calculus detection in screening the breast of
women is important to differentiate marignant frombenign masses. Despite several advances of
acoustic imaging, medical acoustic imagers haveinsufficient capability for small calculus detection
in comparison to X-ray. Therefore the improvementof the ability to detect calculus in acoustic imaging
is strongly desired to serve an effective andlow-cost screening technique without ionizing
radiation.
In this paper, we propose a novel method todetect small calculi utilizing cross-correlation
between RF signals behind the range of ameasurement point, and then evaluate theeffectivity using computer calculation based on thefinite element method.

Z1 and Z2 are the minimum and maximum of the z
coordinates in a region of interest (ROI) behind themeasurement point P(x,z).

The calculus detection of the proposed
method consists of three steps. First, we selectpoints of high echo power, positions with apossibility of the existence of a calculus. We thencalculate the cross-correlation value behind eachselected point. When a small calculus exists in aacoustic beam, the waveform changes behind thecalculus by several causes, as shown in Fig. 2.
Therefore we predict the existence of a calculus
from the decrease of the cross-correlation value.
Cross-correlation

2. Cross-correlation of RF signals behind ameasurement point
The proposed calculus detection method
employs the cross-correlation of acoustic RF
signals behind a measurement point. Figure 1
shows the schema of this process. The
cross-correlation value behind a measurement pointis expressed as follows,ΔXr(x +, z ) = max G ( x, z , l )l2

Measurement pointz2

G ( x, z , l ) =∑ g ( x, z' ) g ( x + ΔX , z'+lΔZ )ProbeFig. 1 Cross-correlation between RF signals ofadjacent scan lines for calculi detection.

z ' = z1
z2∑

g ( x, z ' )z ' = z12

z2

∑ g ( x + ΔX , z'+lΔZ )2z ' = z1

where x and z are the lateral and verticalcomponents of a measurement point on a B-mode
image, g(x,z) is the acoustic RF signal at P(x,z), ΔX
is the interval of scan lines, ΔZ is the range interval,-----------------------------------------------------------taki@sys.i.kyoto-u.ac.jp

3.

Simulation model

To evaluate the effect of the proposed
calculus detection method, we use a simulated
digital tissue map, as shown in Fig. 3. The
formation of the map is as follows; the skin is 2mmin thickness, muscle with minute fat droplets is
located under the skin, a calculus 0.5mm wide is set
at the center for a 10mm depth, and a connective
tissue layer 1mm thick is located for a 15mm depth.

Inhomogenuity

small calculi sensitively.
1
0.98
0.96
Cross correlation

A probe 19.7 mm wide is set at the center on theskin. The probe has 33 elements 0.5mm wide, andthe element gap is 0.1mm. 16 elements areactivated simultaneously to form a scan beam. We
calculate the RF signals utilizing PZFlex, acomputer simulation tool based on the finite
element method [1, 2].

0.94
0.92
0.9
0.88
0.86
0.84
0.82

-4

-2

Small calculus
Correlation
15mm
20mm

Waveform change

Beam 1

Beam 2

Fig. 2 Schema of the decrease of the cross-correlation
value when a small calculus exists in a scan line. The
waveform of an ultrasound pulse changes after passing
through the calculus, and thus the cross-correlation
value behind a calculus decreases.

02
x coordinates (mm)4

Ave - 2sd
15mm
20mm

Fig. 4 Schema of the decrease of the cross-correlation
value when a small calculus exists in a scan line. The
waveform of an ultrasound pulse changes after passing
through the calculus, and thus the cross-correlation
value behind a calculus decreases.

Acknowledgment
This work is partly supported by the Research andDevelopment Committee Grants of the Japan
Society of Ultrasonics in Medicine, Japan and theInnovative Techno-Hub for Integrated Medical
Bio-imaging Project of the Special Coordination
Funds for Promoting Science and Technology, from
the Ministry of Education, Culture, Sports, Scienceand Technology (MEXT), Japan.
References
1. J.A. Hossack and G. Hayward: IEEE Trans.
Ultrason. Ferroelect. Freq. Contr. 38(1991) 91.
2. R. Lerch, IEEE Trans. Sonics Ultrason.
SU37(1990) 233.

Fig. 3 Digital tissue map used in this study. A calculus
0.5mm wide set at the center for a 10mm depth.

4.

ResultFigure 4 shows the cross-correlation values
and their average minus twice the standard
deviation when a calculus of 0.5mm wide exists atthe center, where the ROIs for the cross-correlation
values are at the depth of 15mm and 20mm, and thesummation interval in the vertical direction is 5mm.
The cross-correlation values at the center, theposition of the small calculus, decreases
considerably. This indicates that the proposed
calculus detection method has an ability to detect

2P7a-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 279- 280
11-13 November, 2008

Experimental study of high-resolution ultrasonicimaging for multiple target detection with frequency
domain interferometry
周波数領域干渉計法による複数目標検出における高分解能超音波イメージングの実験検討
Tomoki Kimura‡, Hirofumi Taki, Takuya Sakamoto and Toru Sato (Graduate School ofInformatics, Kyoto Univ.)
木村智樹‡, 瀧宏文, 阪本卓也, 佐藤亨 （京都大 情報学）

1. Introduction
To improve diagnostic technique formetabolic syndrome such as diabetes mellitus, weneed high-resolution imaging technique for a layer
structure of a carotid wall. In this study we apply aradar technique, frequency domain interferometry(FDI), to medical ultrasonic imaging.
2. High-resolution imaging with FDI
2.1. The processing methods of FDI

Amplitude

We estimate the interval of multiple
targets within a range gate using the phases ofsignals at different frequencies. The phasedifference between two signals from different
targets is proportional to the product of thefrequency and the target interval. Thus the phasedifference varies with the frequency of a signal, as
depicted in Fig. 1. The variance of the phasedifference between two signals at different
frequencies is proportional to the product of thefrequency difference and the target interval.
Therefore we can estimate the target interval
utilizing the variance of the phase difference. To
obtain a range profile, we calculate correlation
values between signals at different frequencies. We
then integrate the correlation values with weighting
function for phase correction.
1
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1-6

-4

-2
0
Range

2

4

6

TargetStandard distanceFig. 1 Schema of the phases of the signals at
different frequency-----------------------------------------------------------tcfts440@yahoo.co.jp

2.2. Capon method
The beamformer method scans all distances withina range gate. When multiple targets exist within arange gate, the resolution of the beamformer
method deteriorates because of the interference by
the targets at other positions. Therefore we use theCapon method, minimizing the contribution fromother distances subject to a constant response at adesired distance[1].
2.3. Suppressing the coherent interference byfrequency averaging
We
assumemultiple
coherent
interferences are in the echo from a single range
gate. Additionally we also assume that the target
intervals are constant while receiving the echo froma range gate. Under this assumption, the crosscorrelation between the signal from the desired
distance and the coherent interference is nonzero.
The Capon method selects the weighting function tominimize the sum of signals, and thus results in thecancellation of the signal from the desired distance.
To solve this problem, we suppress the correlationof coherent interferences by a frequency averaging
technique. The phase relation of those signals
change differently according to their respective
target distances. Thus it is possible to suppress thecorrelation by averaging the correlation at several
frequencies. In this point, frequency averaging uses
the same principle as spatial averaging. Two
averaging techniques have been proposed forsuppression of the correction[2, 3]. Uniform
frequency averaging (UFA) averages the correlationin uniform weights, and adaptive frequency
averaging (AFA) in controlled weights to suppress
the correlation completely. The resolution of AFA isgenerally higher than that of UFA.
3. Study of experimental dataTrigger

Power Amp

Pre Ampsingle elementtransducer

Techno-Hub for Integrated Medical Bio-imaging
Project of the Special Coordination Funds for
Promoting Science and Technology, from the
Ministry of Education, Culture, Sports, Science andTechnology (MEXT), Japan.

needlehydrophone

Waterpolyethylene sheet
Acrylic board
Water tankFig. 2 Schema of the experiment.
Figure 2 shows the schema of the experimentof this study. Target is polyethylene sheet 0.05mm
thick. Transmit waveform is a monocycle pulse, thecenter frequency is 8MHz, sampling frequency is500MHz.The echo consists of two backscatteringwaves from the front and back of the polyethylene
sheet. We detect two waves from the echo using
FDI, and then estimate the thickness of the sheet.
For a computational simulation of this experimentof the two targets case, we make the pseudo echos1 (t ) = as0 (t ) + bs0 (t − τ ) + n(t )(5)where s0(t) is the echo from acrylic board, a/b is
amplitude ratio of the input signal, τ is the timedelay resulting from the thickness of the sheet, andn(t) is white noise. Figure 3 shows the waveform ofa pseudo echo, where a/b = 0.493, τ = 0.051μs and
S/N = 38.3dB. Figure 4 shows the normalized
brightness distribution of the pseudo echo given by
the beamformer method, the Capon method with
UFA and that with AFA. In this study, 26 signals ofdifferent frequencies are utilized. The frequencies
are selected from 1.5 to 14.0MHz, and the samplinginterval in the frequency domain is 0.5MHz. It isdifficult to separate the echo employing the
beamformer method. Utilizing Capon method twoedges are detected clearly and beam half-value
widths of two edges are 3.09, 1.54μm in UFA and
3.37, 1.24μm in AFA. Estimation error in thickness
is 1.84 μm in UFA and 2.30 μm in AFA. In the ideal
case without noise, we can estimate the correct echo
power from amplitude ratio.
Figure 3 shows the waveform of thepolyethylene echo with the time-windowing andsmoothing. Figure 5 shows the normalized
brightness distribution of this signal. In this case,
we use echo from acrylic board as a reference wave
and we use the same frequencies and the number of
frequency averaging as those of the numericalcomputation. It is difficult to separate the echo
employing the beamformer method. Utilizing
Capon method, two edges are detected andestimation error in thickness is 2.16μm in UFA and0.91μm in AFA.
Acknowledgment
This work is partly supported by the Innovative

References
1. L.Smaini, H.Luce, M.Crochet, and S.Fukao:
J.Atmos.Oceanic Technol. 19 (2001) p.954.
2. O.L.Frost: IEEE ICASSP. 86 (1986) p.2499.
3. K.Takao and N.kikuma: IEEE Trans. Antennas
Propagat. AP-35 (1987) p.1389.
2

Normalized Amplitude

Oscilloscope

1.5 2 targets

Experimental echo

1
0.5 2 targets

Simulation

0-0.5 1 target

Reference

-1

-1.5
-2
-0.5

-0.25

0

0.25

0.5

Fig. 3 The echo from a polyethylene sheet 0.05 mm
thick, the pseudo echo s1(t), and the echo from anacrylic board.
Target 1

Target 2

0-5-10

P(r)[dB]

FG

Capon AFA
Capon UFA
beamformer

-15
-20
-25
-30
-35
-0.1

0

0.1

0.2

0.3

0.4

0.5

Fig. 4 The normalized brightness distribution froma pseudo echo in the case that two targets are
separated by 0.41 λ. Target distances are estimatedusing the beamformer method, the Capon methodwith UFA, and the Capon method with AFA.

Fig. 5 The normalized brightness distribution froma polyethylene echo. (The parameters are same as inFig. 4)

2P7a-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 281- 282
11-13 November, 2008

Beamformer Design to Shield Noise Sources
ノイズ源を遮蔽するビーム設計
Mariko Yamamoto1†, Shin-ichiro Umemura2 and Takashi Azuma1 (1 CRL Hitachi, Ltd.;
2
Facult. Eng., Tohoku Univ.)
山本真理子 1‡，梅村晋一郎 2，東 隆 1 （1 日立 中研; 2 東北大 工）

1. Background and purpose
Strong reflectors are noise sources forimaging living body. Dynamic range of living body
becomes generally between about 40 and 60 dB
with strong reflectors in the visual field as adiaphragm or bones. Sidelobe of these strong
reflector reduces contrast solution in a wide range.
It often inhibits visibility of hypo-echoic structure
like blood vessels and cysts extremely. Uniform
sidelobe reduction method is attained with
beamform optimization which minimizes thedifference of ideal beam shape and actual beam
shape is already reported [1].
But with existing method, in some case, it’sdifficult to design mainbeam -to- sidelobe intensity
ratio larger than strong reflector-to- tissue
background reflectivity ratio. We propose abeamformer design to selectively inhibit sidelobe indirection of strong reflector. To realize our method,
we optimize not only apodization weight but alsodelay time based on constrained least square. We
demonstrated our method by image simulation.

position to shield noise source. With these beam
forms, we calculate beamforming datas to scanbody. Fig.1(c) is a view of beam shapes to scanbody. They are made with beamforming data
calculated with Fig.1(b).
2Scan line 1

3
4
Scan area
Strong reflector
Body
Probe

(a) Positioning of tissues and a imager
Main beam
Desirablebeam shapefor scan line 1

Inhabitation region toshield noise source

For scan line 22.

Proposed algorithm

Our method expects following steps on
imaging.
1. Get a data for calculating desirable beam shapes(Pre-scan).

For scan line 3
For scan line 4(b) Desirable beam shapes

2. Calculate desirable beam shapes by detecting
positions and intensities of reflectors to avoid.

Beam shape used
for scan line 1

3. Calculate apodization data to make beams which
fit in well with desirable shapes.

For scan line 2

4. Scan with calculated apodization data and makean image.
When strong reflector is positioned as Fig.1 (a), we
define desirable beam shapes as Fig.1 (b). Directionof main beam shifts as scan lines but that of
inhabitation region are fixed on strong reflector’s-----------------------------------------------------------mariko.yamamoto.td@hitachi.com

For scan line 3
For scan line 4(c) Actual beam shapes by calculated apodizations
Fig. 1. Concept diagram of our processWe defined apodization weight and delay time ofelements of probes as beamforming data. It’s acomplex number. Optimization algorithm ofbeamforming data to get beams which fit in wellwith desirable shapes is as follows.
We expressed beamfoeming data as a vector p and atransform from beamfoeming data to beam shape asa matrix T. With these expression, beam shape B
becomes
B =Tp.

(1)

Precisely, T is a matrix like⎛ e jL11 / v / t⎜
T =⎜ M⎜ jLM 1 / v / t⎝e

L e jL1 N / v / t ⎞⎟O
M ⎟jLMN / v / t ⎟
L e
⎠

(2)

λ

-30.5dB.

~ 2 D 0dB

-34.0dB

T’s elements describes phase sifts calculated bydistance between each elements (j=1,…,N) to eachposition of field (i=1,…,M) Lij. When desirable
shape is described with vector W, fitness withdesirable shape is evaluated as||WB||2=B†W†WB

hypo-echoic cyst (-30.5dB, -34.0dB, -40.0dB) andlaminar strong reflector (0dB) in background tissue(-30dB). Radius of each cyst is almost double ofbeam width. Example of beam shape of existing/our
method is shown in Fig2 (b-1)/(b-2). 1-D beams areused for ease of calculation. Simulated image withexisting/our method is shown in Fig.2 (c-1)/(c-2).
On existing image, fog made by side-lobes ofstrong reflector is present and especially, visibilityof inside of the cyst is degraded. On the other hand,on our image, fog is suppressed and the visibility of
inside of cysts found improved. With these results,
we assume our method is superior on imaging live
body with strong reflector like bones, especiallyobservation of structure inside of blood vessels or
cysts.

-40.0dB

Background:-30.0dB(a) Phantom(b-1) Existing(3)

Inhabitation region

and transmitting power is evaluated as~10dB(b-2) Ours(b) Beam shape(4)||p||2=p†p.
And now, constrained least square

4.
2

2

δ(||WB|| +λ||p|| )=0(5)

A is applied to get a apodization to form best-fitted
beam shape under constant beam power. And
problem is reduced to an eigenvalue problem
T†W†WTp=λp.

(6)

So we can get a complex beamforming data to
make beam which best-fit with desirable shape byinsertingtransfer function as T, inserting
desirable beam shape as W and solving eigenvalue
problem (6). An eigenvector for maximum
eigenvalue is used as beamforming data to scan.
3.

ResultFig.2 shows a simulation results calculatedwith our complex beamforming data. Imaging
object is shown in Fig.2 (a). It contains 3

(c-1)
(c-2)
Existing Ours(c) Simulated images
Fig.2 Simulation result

Conclusion

We proposed an beamformer design toselectively inhibit sidelobe in direction of strong
reflector. Optimized complex beamforming data is
obtained as an eigenvector of a matrix which wasmade from desirable beam shape and beamforming
data - to - beam field transfer matrix. With thisoptimization , noise shield can be realized. We
demonstrated our method by image simulation.
References
1. K.Ranganathan et al: IEEE trans. on ultrason.,Ferroelect., Freq. Contr., 50(1) (2003) 15.

2P7a-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 283- 284
11-13 November, 2008

Optimum Quadratic Filters for Nonlinear
Ultrasonic Imaging
Pornchai Phukpattaranont† and Chusak Limsakul (Facult. Eng.,
Prince of Songkla Univ.)

1. Introduction
The state-of-the-art pulse-echo ultrasoundimaging systems exploit nonlinear behavior frominteraction between acoustic energy and media toimprove spatial and contrast resolution. Somenonlinearities are generated by ultrasound contrast
agents (UCAs) [1] while others are formed by the
propagation of sound in tissue [2]. We havevalidated the use of a quadratic filter (QF) for
separating the linear and quadratic components ofthe beamformed radio frequency (RF) data inpulse-echo ultrasonic imaging [3]. Based on theunderstanding of the QF in the frequency domain in[4], the novel QF design is formulated andpreliminary evaluation is given in [5]. In this paper
we present details on parameter adjustment in the
QF design for the improvement of imaging quality.
2. Theory
The design of QFs for capturing the second
order nonlinearities is performed in frequency
domain. The linear-phased QF is designed based on
the sum of two 2D Gaussian filters where theircenters are placed at the maximal contrast-to-tissue
ratio of UCA over surrounding tissue. In the design,
parameters are varied and investigated in order toachieve the best filter for enhancing imaging quality
both in terms of contrast and spatial resolution. Our
goal in the design is to calculate coefficients of the
QF, h(n1, n2), from the frequency response given by
H (e jω1k , e jω2 l ) = G (ω1k , ω 2l )e jφ (ω1k +ω2l )(1)where G(ω1k, ω2l) represents the desired magnitude
response based on the 2D Gaussian filters and φ(ω1k,ω2l) is the phase response. Parameters to be
optimized are as follow: the center of Gaussian
filter, the rotation angle (θ), the width of the
passband along the cross-diagonal (σx) and diagonal
orientations (σy). Please see [5] for details.
In the design, the centers of the Gaussianfunctions are positioned at frequency pairs where
the contrast-to-tissue (CTR) ratio is maximal along
the main diagonal of 2D frequency plane. The
bandwidth of filter is independently determined to
optimize spatial resolution. Therefore, the design-----------------------------------------------------------E-mail address: porncahi.p@psu.ac.th

approach offers two degrees of freedom in
maximizing the CTR and spatial resolution
simultaneously. This avoids the inherent tradeoff
between contrast and spatial resolution when linear
filters are used (e.g. in second harmonic imaging).
After the filter coefficients h(n1, n2) are obtained,
the QF image is produced by applying the quadratic
filter coefficients to the beamformed RF data
throughout the standard B-mode image to estimate
the quadratic component
N −1 N −1

y (n) = ∑ ∑ h( k1 , k2 ) x( n − k1 ) x(n − k2 ).

(2)

k1 = 0 k 2 = 0

3. Results and discussion
We investigate and evaluate the proposed
design with RF data acquired from a flow phantom(Model 524; ATS Laboratories, Inc., Bridgeport,CT) containing flow channels embedded inrubber-based tissue mimicking material. The
contrast agent, BR14 (Bracco Research S.A.,
Geneva, Switzerland), was used. While UCA with
1:4000 dilution was circulated through the 6-mm
channel, UCA with 1:10000 dilution was circulated
through the 4-mm channel. The B-mode image isshown in Fig. 1(Top Left). The strength of echoesfrom UCA with 1:4000 dilution in the 6-mm flow
channel (CTR = 5.5 dB) is higher than those from
UCA with 1:10000 dilution in the 4-mm flow
channel (CTR = 2.9 dB).
Fig. 2 (Right) shows the magnitude of 2D
frequency responses of the QFs under investigation.
The centers of Gaussian function are at frequency(-2, 2) and (2, -2) MHz. Other parameters, i.e., (σx,σy, θ) for the QF1, QF2, and QF3 are (1.1, 0.55,−π/4), (0.55, 0.55, −π/4) and (0.55, 1.1, −π/4),
respectively. Fig. 2 (Left) shows the corresponding
coefficients of the QFs. The size of the QF1, QF2,
and QF3 are 37, 47, and 37, respectively. The
corresponding QF images are shown in Fig. 1 with
the CTR values of 23.8, 25.2, and 16.1 dB.
Although the CTR of QF2 is highest, there is loss of
axial resolution compared with that from the QF1.
Additional study on resolution is carried out
using the images from a quality assurance phantom.
Fig. 3 shows the B-mode image of the quality
assurance phantom and the QF images resulting
from the same QF kernels used to generate QF
images of the flow phantom in Fig. 1.

Fig. 1 Top Left: B-mode image of a flow phantom.
Images from the QF1, QF2, and QF3 are shown at Top
Right, Bottom Left, and Bottom Right, respectively.

Fig. 2 Left: Coefficients of the QF. Right: The
magnitude of 2D frequency response of the QF.

Fig. 4 shows axial lines through the center ofthe quality assurance phantom. It can be seen thatthe axial resolution of the QF1 image is better thanthat from the QF2 and QF3. Based on thedemonstrating results, we conclude that the QF withwider bandwidth in cross-diagonal orientation
provides the QF image with better axial resolution.
Acknowledgment
The authors thank Professor Emad S. Ebbini
for his suggestions and support in this work. In
addition, this research project was funded by a grantfrom the Thailand Research Fund and Commission
on Higher Education through Contract No.
MRG5080287.

Fig. 3 Top Left: B-mode image of a quality assurance
phantom. The images from the QF1, QF2, and QF3 areshown at Top Right, Bottom Left and Bottom Right,
respectively.

Fig. 4 Axial lines through the center of the quality
assurance phantom. Thick: The QF1. Thin: The QF2.
Dash: The QF3.

References

1 P. J. A. Frinking, A. Bouakaz, J. Kirkhorn, F. J.
Ten Cate, and N. de Jong: Ultrasound Med. Biol.
26 (2000) 965.
2 M. A. Averkiou: Proc. IEEE Ultrasonic Symp.,
2000, p. 1563.
3 P. Phukpattaranont and E. S. Ebbini: IEEE Trans.
Ultrason., Ferroelect., Freq. Contr., 50 (2003)
987.
4 P. Phukpattaranont and K. Chetpattananondh:
Proc. Symp. Ultrason. Elec, 2005, p. 281.
5 P. Phukpattaranont, T. Nilmanee, C. Limsakul,
and E. S. Ebbini: Proc. IEEE Ultrasonic Symp,
2007, p. 2211.

2P7a-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 285- 286
11-13 November, 2008

Tissue Boundar y Imaging Based on Eigenvalue Decomposition
固有値分解による組織境界イメージング
Hironari Masui1†, Takashi Azuma1 and Kazuaki Sasaki2(1 Hitachi CRL, 2Tokyo Univ. of A&T)

増井裕也 1‡，東隆 1，佐々木一昭 2 （1 日立 中研; 2 農工大 農）

1. Introduction
Defining the boundary between a tumor
region and surrounding normal tissue is essential
for non- and minimally invasive therapies. Tissue
strain imaging was effective for tissue
characterization [1], but it involves a computational
complexity. That is possible to be transformed tocolor map. Tissue boundary on the color map is notalways clear becouse of nonlinearity oftransformation [2]. Several groups have studied thevector maps of tissue motion to investigate theelasticity of tissue [3].
We have proposed a new method of ultrasonicstraingraphy
basedon
detectingspatialdiscontinuity in the tissue motion vector, estimatedby the correlation of images between sequential
frames [4,5]. To transform from a vector map to ascalar one, we tried a variety of parameters: vector
length or angle, etc. However tissue boundary is notnecessarily clearly depending on the situation
because vector length or angle do not sufficiently
reflect information of vector map.
In order to obtain adequate scalar map,
eigenvalue decomposition technique is applied.
First of all, a vector map in ROI (region of interest)
is converted into a complex matrix by regarding
component x as real part and componet y as
imaginarypart.
Secondly,
eigenvalue
decomposition is applied to the complex matrix.
The feature of mixed vector pattern is possible to be
extracted by decomposing as eigenvalue
components. Consequently, boundary imaging isadequately performed.
A VX2 tumor implanted in the liver of a rabbit
were chosen to test our new method. The boundary
between the tumor and the normal tissue
surrounding it was not clearly detected in B-mode
images, but it could clearly be seen with the method
we propose.
2. Boundar y imaging method
The outline flowchart for tissue boundary
imaging is shown in Figur e 1. The image frames
were obtained from an EUB-8500 ultrasonicscanner (Hitachi Medical Corp., Tokyo, Japan) andhand-held fixing linear array probe EUP-L54M(Hitachi Medical Corp., Tokyo, Japan). The probe
was operated at a frequency of 9 MHz.
60
5

50

10
15

40

20
25

30

30
35

Detectingmotion vector

40
45
50
55
10

20

30

40

50

60

20

10

0

0

10

20

30

40

50

60

70

Filtering vector map
l ength ( org.si ze)

15

10

Imaging of
scalar parameter

5

0

10

20

30

40

50

60

Fig. 1

0

2

4

6

8

10

12

14

16

18

Outline flowchart

A motion vector is detecting from two image
frames based on block matching method [6]. A
window array was set in each frame to measure
motion. If the window was too small, the reliabilityof the motion vector that was detected wasinsufficient. If the window was too large, thecorrelation between consecutive frames was lostcaused by deformation in the window. A window
size of 30×30 pixels was selected based on
consideration of this tradeoff. The best region formatching was found from a search area of 50×50
pixels set in the next frame by searching theminimum points for subtraction, absolution, andsummation in the results. A VX2 tumor implanted
in a rabbit liver were imaged as an experiment.
Since the VX2 tumor could be moved byrespiratory motion, pushing with an ultrasoundprobe was unnecessary in these cases.
After the tissue motion vector was mapped, an
image processing, which is the moving averagetechnique, applied to vector map. We set ROI at asize of speckle caused by ultrasonic measurement.
In order to detect spatial discontinuity in the motion
vector, an scalar map is imaged by using eigenvalue
decomposition.
Figur e 2 is a flowchart for computing scalarcomponent. A window (ROI) array was set in each

vector map to obtain scalar map.
A vector map in ROI is converted into acomplex matrix by regarding component x as real partand component y as imaginary part. A complex matrix(m×m) is generated as follow:

A

A11 X

iA11Y

A12 X

A21 X

iA21Y

･･･
Am1 X iAm1Y

iA12Y ･･･

A1mX

iA1mY

･･･

･･･ A2 mX

iA2 mY

･･･
･･･

･･･
･･･
･･･ AmmX iAmmY.

(1)

Figur e 4 shows the scalar component computedfrom the vector map. Figur e 4(b) is obtained byeigenvalue decomposition. A window size of 3×3
pixels was selected on trial. For comparison, tensor
imaging computed under the same conditions isshown in Figur e 4(a). The tensor imaging shows thedisconnected boundary between the tumor andsurrounding normal tissue, while Figur e 4(b) shows
the boundary which is clearly detected.

Eigenvalue decomposition is applied to thecomplex matrix.
Ap k

A k k
k

m

: eigenvalue (complex number )(2)

p k : eigenvector (m 1).

Eigenvalues are obtained. A scalar value isdetermined from the eigenvalues. Maximum absolutevalue of eigenvalues is selected as scalar one in thispaper.

(a) Tensor imaging

Obtaining vector map
Setting measurement window array
Selecting measurement window
from measurement window array
Eigenvalue decompositionNo

All measurement window
estimated
Yes
Stop

Fig. 2 Flowchart for computing scalar component

3. Exper imental result

Figur e 3 shows a B-mode image and vector
map of tissue motion for the VX2 tumor implanted
in rabbit liver.

(a) B-mode image(b) vector map
Fig. 3 VX2 tumor implanted in rabbit liver(b) Eigenvalue decomposition
Fig. 4 Scalar components computed from vector map

4.

Conclusion

We proposed the boundary imaging method
based on eigenvalue decomposition. Eigenvalue issufficientry reflect information of vector map. Thismethod has possibiity of obtaining fine structure oftumor.
References
1. T. Shiina et al.: J. Med. Ultrason. 29 (2002) 119.
2. N. Nitta et al.: IEICE J 84-A (2001) 1405 (inJapanese).
3. Y. Yamashita and M. Kubota: Proc. IEEE
Ultrason. Symp. (1990) 1371.
4. T. Azuma et al.: Proc. IEEE Ultrason. Symp. (2006)
2040.
5. H. Masui et al.: Proc. Symp. Ultrason. Electron. 28(2007) 429.
6. H. Yoshikawa et al.: Jpn. J. Appl. Phys. 45 (2006)4754.

2P7a-20

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 287- 288
11-13 November, 2008

Reconstruction of shear modulus with mechanicalsource
ずり弾性率と力源の再構成
Chikayoshi Sumi†, Sayaka Suekane (Facult. Sci. Tech. Eng., Sophia Univ.)
炭親良‡，末包明夏 （上智大 理工）

1. Introduction

2. Methods

We have developed various strain-measurement
based shear modulus reconstruction methods, e.g.,
1-dimensional [1] and multidimensional (2D and
3D) [1-3] methods. For a multidimensional
reconstruction, Methods A to C [2,3] use a mean
normal stress as an unknown, whereas Method F [1]uses a typical Poisson's ratio. In a dynamic
deformation case, a density can also bereconstructed together. In addition, in Methods A to
C and F, by using an iterative solution (e.g.,
conjugate gradient method) with no references, ashear modulus reconstruction being dependent of
the initial estimate of the iterative solution can beobtained (Method D), whereas by using aquasi-reference shear modulus (e.g., unity) insteadof an absolute shear modulus, a relative shear
modulus reconstruction can be achieved (MethodE) [4,5]. Both Methods D and E are useful when thetarget tissue is deeply situated (e.g., liver, heart)because no geometrical artifacts are yielded.
Although all 3D reconstructions can deal with
arbitrary mechanical sources (e.g., high intensity
focus ultrasound, static compressor, vibrator, heart
motion, pulsation etc.) existing outside a region ofinterest (ROI) [i.e., external sources], the existenceof a mechanical source in the ROI [i.e., an internalsource] make the Methods impossible to achieve
the reconstruction of shear modulus.
In this study, we extend the reconstruction
methods such that arbitrary internal mechanicalsources (i.e., expressed as a static or dynamic
pressure or a force vector) can be reconstructed
together with the shear modulus [5-7]. However,
because in 1D and 2D reconstructions, both theinternal and external mechanical sources will affectthe shear modulus and source reconstructions as insolo shear modulus reconstruction [1-3] (i.e., due tothe low dimensionalities), we also evaluate theeffects of the mechanical source conditions (size,
intensity, frequency etc.) on such low dimensional
reconstructions.

Basically, dynamic deformation cases are dealt
with. As mechanical source models, a pressure orforce vector can be dealt with. Thus, strictly, thenumber of unknowns cannot be larger than three.
Thus, if necessary, a typical density value will be
used, or the more equations will be obtained under
the assumption that the mechanical source isstationary.

-----------------------------------------------------------c-sumi@sophia.ac.jp

3. Simulations

A tissue phantom (50 mm side cube) andmechanical sources were simulated using
successive-over-relaxation method. For instance, aspherical source (5 mm dia.) that partiallyoverlapped a spherical region having a different
shear modulus from that of the surrounding region(e.g., 2 vs 1 x 105 N/m2) is used.
For a static deformation case, the unknowns are amechanical source and for Method F, a shear
modulus and for Methods A to C, a mean normal
stress and a shear modulus. For Methods A to C,
because a mechanical source can be considered to
be dealt with by combining with a mean normal
stress, in these cases, we refer to the Methods as
Methods A’ to C’. Furthermore, the inertia can also
be combined with the mean normal stress and themechanical source (The Methods are referred to as
Methods A” to C”).
As mechanical sources, (i) a pressure p, (ii) a
force component in a depth direction and (iii) a 3D
force vector were dealt with.
In a similar way, dynamic cases were also dealt
with. Here, only the reconstructed images obtainedin static cases are shown.
As the results obtained by Method F, formechanical source (i) to (iii), a shear modulus wasable to be reconstructed with a high accuracy (Fig.
1a). However, mechanical sources were not able tobe accurately reconstructed (omitted).
However, when using Methods A to C, for (i) to(iii), all the shear modulus, the mechanical sourcesand the mean normal stresses were reconstructedwith high accuracies (Fig. 1b).
Interestingly, for (i) to (iii), Methods A’ to C’yielded accurate shear modulus reconstructions (Fig.
1c). Methods A’ to C’ are also effective methods.
For 3D reconstructions, internal mechanicalsources was able to be reconstructed together. Afterthe solo shear modulus reconstructions using
external sources [1-3], internal sources can also bereconstructed using the strain tensor data. In
contrast, in 1D and 2D reconstructions, the use of asmall mechanical source yields smaller shear
modulus values than the original.

Shear(a) Method F

Shear

Mechanical source(b) Method C

Shear(c) Method C’
Fig. 1. Reconstructions obtained when a mechanicalsource (i) exist in an ROI.

4.

Discussions and conclusions

We succeeded in the shear modulus
reconstructions even when internal mechanicalsources exist in an ROI by allowing thesimultaneous reconstruction of the mechanicalsources. The reconstruction will also allows theestimation of point spread function [6]. For 1D and
2D reconstructions, mechanical sources should belarge. Other results obtained including experimental
ones will also be reported.
The reconstruction of the mechanical source canbe used for designing US beamformer for US
imaging, controlling tissue deformation (i.e.,elasticity imaging) and high intensity focus
ultrasound (HIFU) treatment [6,8]. For suchreconstructions, an accurate tissue tracking
algorithm (i.e., our developed phase matchingalgorithm [1]) should be used.
We should also mention the case where thereconstruction target is a stress tensor [5,7]. As
described above, mean normal stress can bereconstructed. Hydrostatic pressure in fluid can also
be reconstructed together with fluid parameters inthe same manner [5,7]. Thus, other stress tensor
components can be evaluated using thereconstructed mechanical properties and mean
normal stress or hydrostatic pressure together withthe measured deformations.
References
1. C. Sumi et al.: IEEE Trans UFFC 52 (2005)
1670.
2. C. Sumi et al.: IEEE Trans UFFC 53 (2006)
2416.
3. C. Sumi et al.: IEEE Trans UFFC 54 (2007)
2394.
4. C. Sumi et al.: Acoustical Imaging 29 2007 (inpress).
5. C. Sumi et al.: Acoust Sci Tech (under review).
6. C. Sumi et al.: IEEE 2007 Int Ultason symp,
1557.
7. C. Sumi: USA patent application 11/334,089, Jan.
18, 2006 (JP-2005-14774, Jan. 21, 2005).
8. C. Sumi et al.: Jpn J Appl Phys 47(5B) (2008)4137.

2P7b-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 289- 290
11-13 November, 2008

Characterization of Ultrasound Generated Protein
Microbubbles: From Production to Destruction
Judy Lee‡, Atsuya Towata, Kyuichi Yasui, Teruyuki Kozuka, Toru Tuziuti and Yasuo
Iida (National Institute of Advance Industrial Science and Technology ( AIST))

Protein microbubbles have generated
substantial interest over the years due to theirdiverse biomedical applications such as echo ormagnetic resonance contrast agents and as a vehicle
for targeted drug deliveries. The production of
microbubbles is important in terms of the size
distribution, concentration and shell thickness andstrength. These characteristics can govern the
microbubble’s scattering properties and more
importantly destruction by dissolution or ultrasound.
Destruction by ultrasound can be detrimental forecho contrast agent purposes, but beneficial for
applications such as drug release. In this study,
bovine serum albumin microspheres were generated
by high intensity ultrasound and the importance ofsolution temperature was investigated. The
destruction of microbubbles by dissolution andultrasound is also discussed.
2. Method
Bovine serum albumin (BSA) microbubbles
were produced by sonicating 5 wt% of BSA under ahigh intensity ultrasonic horn (Branson Ultrasonics,
D450, 20 kHz) at a power of ≈ 200 W/cm2 for 10
seconds. The BSA microbubbles were confirmed bylabeling with the fluorescent dye rhodamine B
isothiocyanate (RBITC) and viewed under UV
illumination with a microscope equipped with an
Olympus U-MSWG2 filter (appropriate for RBITC).
The bubble size distributions were characterized by
Coulter® MultisizerTM II analyser fitted with a
100 μm aperture and confirmed with lightmicroscopy images. Different size distributions canbe isolated by allowing the microbubbles to rise in avial and collecting either the top or bottom fraction
after a certain period of time. A microbubble size
distribution of around 10 μm was used in this study.
Destruction of BSA microbubbles by ultrasoundwere performed by immersing a glass vial
containing 5 mL of microbubble solution in a liquid
filled vessel with either a 727 kHz or 2 MHztransducer fitted at the bottom. A driving power of
40 W, measured by a power meter, was used.
3. Results and Discussion
Production: A typical light microscopy imageof ultrasound generated BSA microbubbles isshown in Fig. 1(a). The BSA shells were confirmed
by incubating the microbubbles in RBITC dye(Fig. 1(b)). A fluorescence image of a BSA shellfrom a collapsed microbubble, depicted in Fig. 1(c),shows a very thin shell of less than 1 μm.
It has been shown in the literature that thegeneration of BSA protein microbubbles is due tothe cross-linking of cysteine groups to form
disulfide bridges by superoxide radicals generated
by sonication1. However, it was found in this study
that microbubbles were produced even under highshear homogenization. It can be observed in Fig. 2that the number of microbubbles produced
increases with increasing solution temperature, but
the size distribution is not significantly affected. To
obtain a high yield of microbubbles, the solution
temperature needs to be near the protein
denaturation temperature (62oC for BSA2).
Destruction: Protein microbubbles cancollapse via diffusion of gas across the shell into thesurrounding liquid3. This rate is accelerated indegassed mediums. To observe the behavior of the
BSA shell during microbubble dissolution,
fluorescent labeled BSA microbubbles were
injected in mildly degassed water and the collapseof a 10 μm BSA microbubble is captured by a CCD

Fig. 1: (a) Light microscopy image of BSA microbubbles.
(b) and (c) Fluorescence image of RBITC labeled
microbubbles.
Relative Number of Microbubbles

1. Introduction

1.2

40 oC

50 oC

60 oC

1
0.8
0.6

100 μm

100 μm

100 μm

0.4

8.18 x 107 mL‐1

1.16 x 108 mL‐1

2.18 x 108 mL‐1

4

10

0.2
0
2

6

8

12

Bubble Size [μm]

14

16

18

20

Fig. 2: Effect of solution temperature on the concentrationand size distribution of BSA microbubbles produced from10 second sonication.

Relative
Numberof Microbub
Relative
Numberof Microbubbles

0 SEC

1

20 μm

0.8

10 μm

0

14

0.6

100

60 SEC

0.4

20 μm

0.2

273

320

Fig. 3: Selecterd frames from a frame rate of 30f/s
documenting the collapse of a 10 μm bubble due to the
diffusion of gas in a degassed medium.

(a)

(b)

IntactCollapsed

IntactCollapsed

Fig. 4: (a) Light illumination showing microbubbles thathas been dried on a glass plate. (b) Same sample as (a)but showing fluorescence emission from microbubbles
that were not cross-linked by glutaraldehyde.

camera (Fig.3). Initially the microbubble isspherical, but deviates from sphericity (frame 0) as
gas slowly diffuses out from the microbubble core.
This diffusion lowers the pressure inside themicrobubble and causes the shell to buckle(frame 14). Frames 100 to 320 illustrate thecollapse of the shell as the microbubble deflates
through a small rupture caused by the buckling. The
same collapse of microbubbles was observed whena layer of microbubble is dried on a glass plate.
BSA microbubble shell can be strengthened
by increasing shell thickness or with a cross-linking
agent such as glutaraldehyde (GA), which crosslinks the amine group of lysine. The effect of GA on
the strength of the microbubble shell isdemonstrated in Fig. 4. A mixture of microbubbles
with and without GA cross-linking is dried on a
glass plate. In order to distinguish between the twodifferent microbubbles, microbubbles that were notcross-linked were fluorescent labeled with RBITC.
Fig. 4(a) is an image of the dried sample mixture
viewed under normal light illumination. It showsthat some microbubbles have collapsed, whileothers appear to be still intact. The same sample
was illuminated under UV to identify microbubbles
without GA cross-linking (Fig. 4(b)). It can beobserved by comparing the two images thatmicrobubbles that did not collapse during drying
were microbubbles with shells cross-linked by GA.
The destruction of BSA microbubbles with anaverage size of around 10 μm by ultrasound isshown in Fig. 5. At a frequency of 727 kHz andpower of 40 W, bubbles around 10 μm weredestroyed in 60 sec leaving few bubbles around

120 SEC

0

20 μm

6

10

14

18

22

Bubble Size [μm]2630Fig. 5: Effect of sonication time on size distribution of
microbubbles (727 kHz with an applied power of 40 W).
Relative Number of Microbubbles

216

1.4

2 MHz

1.2

727kHz

1
0.8
0.6
0.4
0.2
0
0

10

20

30
40
50
60
Sonication Time [s]7080

Fig.6: Change in the number of 10 μm microbubbles as afunction of sonication time at a power of 40 W.

20 μm as confirmed by the light microscopy images.
These larger bubbles were destroyed with longer
sonication times. The destruction of 10 μm
microbubbles as a function of time for 727 kHz and
2 MHz is shown in Fig. 6. It shows thatmicrobubbles were completely destroyed by
727 kHz in 30 sec, whereas only 30 % weredestroyed by 2 MHz after 60 sec. This effect may
be due to large microbubbles having a lower
resonance frequency. It has been shown that whendriven at resonance, microbubbles undergo large
expansions which lead to fragmentation of protein
shells3. However, it is also known that the pressure
threshold for acoustic cavitation increases withincreasing frequency. This may also contribute to
the lower number of microbubbles destroyed at
2 MHz compare to 727 kHz.
Acknowledgement
This work is supported by the JSPS
Postdoctoral Fellowship program and the Ministryof Education, Culture, Sports, Science andTechnology of Japan.
References
1. M. W. Grinstaff and K. Suslick: Proc. Natl. Acad.
Sci. USA 88 (1991) 7708.
2. M. Ruegg, U. Moor, and B. Blanc: J. Dairy Res.
44 (1977) 509.
3. P. A. Dayton, K. E. Morgan, A. L. Kilibanov, G.
H. Brandenburger, and K. W. Ferrara: IEEE
Trans. Ultrason., Ferroelectr., Freq. Contr. 16(1999) 220.

2P7b-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 291- 292
11-13 November, 2008

Study of effect in active path selection of fluid
microcapsules to the variation of ultrasound emission at
the bifurcation point
流路分岐部における照射超音波の変化に対するマイクロカプ
セルの流路選択効率の検討
Yusuke Muramatsu1‡, Sawami Ueda1, Ryusuke Nakamoto1, Yusuke Nakayashiki1,
Kohji Masuda1, and Ken Ishihara2 (1 Tokyo Univ. Agri.& Tech.; 2Ehime Univ.)
村松悠佑 1‡, 上田沢美 1, 中元隆介 1, 中屋敷悠介 1, 桝田晃司 1, 石原謙 2（1 東京農工大; 2 愛媛大）1. Introduction
Making use of the phenomena that microcapsules or
microbubble of µm order collapse themselves after
ultrasound emission near their resonant frequency,
physical DDS (Drug Delivery System) has been
proposed[1,2]. To minimize the side effect of
medication, drug should affect to the target area, notto other parts inside human body. Though recent
mainstream of DDS is focused on the genetransduction by using gene vector, it takes time andcost to develop for each object. The microcapsules,
which can contain the specified drug inside theshell, have the possibility to correspond to various
kinds of medications. The distribution of thecapsules is easily recognized by echogram (B-mode
image) because the brightness of echogram varies
according to the density of capsules. However, it
was difficult to enhance the efficiency of
medication because the capsules diffuse after the
injection, where motion of the capsules in the bloodflow cannot be controlled. In this paper we describe
our attempt for active path selection of
microcapsules in the artificial blood vessel by
acoustic radiation force[3].

Fig.1 Experimental setup including artificial bloodvessel.

2. Experiment
We used microcapsule F-80E(Matsumoto Oil,Japan) which shell is made of PVC(polyvinyl
chloride) with specific gravity as 0.0225 andaverage of diameter as 99.2 [µm]. We sieved it as
the range of diameter is from 65 to 73 [µm] becauseof the limitation of magnification in the microscope.
Also we have prepared the artificial blood vessel,
which is made of PEG(polyethylene glycol),including the Y-form bifurcation as Fig.1. The
external size is 50x80x10 [mm] and inner diameterof the path is 2 [mm]. The axis of the transducer is
set 50 [deg] to x-y plane and 60 [deg] to y-z plane asshown in Fig.2. Defining the point O as theintersection of three paths, the points P, Q and R
indicate 1, 2 and 3[mm] upper from O, respectively.
-----------------------------------------------------------masuda_k@cc.tuat.ac.jp

Fig.2 Schematic view of the artificial blood vessel

To evaluate the amount of capsules which passes
through each path, we have extended two lower
courses by using semi-transparent tube andestablished the observed area which includes themin the same view as shown in Fig.1. By using a
microscope (BX50, Olympus, Japan), optical imageof observed area is recorded.
3. Results

Fig.3 shows microscopic images of the area, which
are captured by using high-speed camera
Phantom-V4.2 (Nobby tech Co. Ltd, Japan) withinterval time as 2 [ms]. To measure the capsules∑∑ f ( x. y)

shadow index = REF − x =0 y =0

S

(1)

Where f is brightness of the ROI, REF is brightness
average without capsules and S is area of the ROI.
Then we have confirmed the relation between
shadow index and capsules density.

pressure as 160 [kPa], flow velocity as 100 [mm/s]
and capsules density as 0.2 [g/L], ultrasound was
focused at points O, P, Q shown in Fig.2. Fig.5
shows the value of shadow indices for each focusedpoint.
1.6

Shadow index

amount, we established two square regions ofinterest in each course (ROI A, ROI B) andcalculated the brightness average. The brightness ina region decreases according to the number ofcapsules inside. Thus we defined the shadow index
as the following equation to evaluate the amount of
capsules in the ROI.
m n

1.4

ROI A

1.2

ROI B

1
0.8
0.6
0.4
0.2
0
O

P
Q
Ultrasound forcused point

R

Fig.5 Capsules path selection efficiency depending on
the ultrasound focused position.

When the ultrasound was focused at point O, there
was no difference between two ROIs. However,more than 90 [%] of capsules were introduced topath B when the ultrasound was focused at point Q.
Thus focused point of ultrasound emission and theshape of the bifurcation should be considered torealize active path selection of capsules.
4.Discussion
Fig.3 Time series images of the observed area by 500[fps] after injection of capsules suspension withultrasound emission.

Capsules suspension passed through the ROI
without ultrasound and calculated the average of
shadow index for 15 [frames] (duration 30 [ms]) for
various flow velocities. As the result shown in Fig.4,
using the density in capsules as 0.15-0.25 [g/L],
significant change of density can be detected.

Shadow index

1.5

5.Conclusions
In this study, we have experimented and considered
to realize active path selection of microcapsules at abifurcation of the artificial blood vessel. We aregoing to apply the experiment by varying otherparameters and to investigate the mechanism of thisphenomena.

2.5
2In this study, we used the microcapsules which size
is 63〜75[μm] which cannot be applied to in vivo
experiment. Because acoustic radiation force is
proportional to the volume of capsules, it should be
1/100 when the diameter of capsules is several
microns. Thus the blood velocity to be applied thistechnique is limited to few [mm/s]. Therefore wehave to devise the minimization of the artificial
blood vessel and its observation system.

100[mm/s]
200[mm/s]
300[mm/s]

1
0.5
0
0.05

0.1

0.15
0.2
Capsules density [g/L]

0.25

Fig.4 Shadow index versus capsules density.

We measured the shadow indices in two ROIs using
various conditions in emission of sinusoidal
ultrasound. When frequency as 1 [MHz], sound

References
1. D. Koyama, W. Kiyan and Y. Watanabe：Jpn.
J. Appl. Phys. 43 (2004) 3215-3219.
2. Y. Yamakoshi and M. Koganezawa：Jpn. J.
Appl. Phys. 44 (2005) 4583-4587
3. Y. Muramatsu, K. Masuda, S. Ueda, K.
Ishihara ： Proc. Symp. Ultrason. Electron,
Vol.28, (2007), 407-408.

2P7b-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 293- 294
11-13 November, 2008

Bi-frequency driven transducers
for multi-frequency ultrasonic imaging
多周波超音波イメージングのための二周波駆動振動子
Natsuki Yoshizumi1†, Shigemi Saito2, Daisuke Koyama3, Kentaro Nakamura3 andIwaki Akiyama1 (1 Facult. Eng., Shonan Inst. of Tech.; 2School of Marine Sci. andTech., Tokai Univ.; 3Precision. and Intelligence Lab., Tokyo Insttiute of Tech.)

吉住夏輝 1‡，斎藤繁実 2，小山大介 3，中村健太郎 3，秋山いわき 1 （1 湘南工大 工; 2 東海大 海洋;
3
東工大 精研）1. Introduction
Wideband ultrasonic system can effectively
reduce the speckle noise on echographic images byapplying the frequency compound technique1). The
authors developped ultrasonic transducers2-8), which
form multiple frequency beams based on the
nonlinear acoustic propagation. The transducerestransmit ultrasonic puleses, which consist of
frequency componets f1 and f4, which is the quadfrequency of f1. As secondary waves, f2, f3 and f5 are
generated by the nonlinear interaction through themedium. They are the second harmonic of the f1, thedifferece between f1 and f4, and the sum of f1 and f4,
respectively. Generally, it is difficult to excite theultrasonic pulses of the fundamental vibration modeand the higher-order vibration mode of evennumbers simultaneously by a single transducer.
This problem can be solved by adopting double
layer for the structure of the transducer. We candetermine thickness of the layers and selectelectrodes suitable for the each modes so that thedesired vibration modes are excited efficiently. In
this report, we mesured profiles of the ultrasonicbeams which are formed by two different type ofbi-frequency driven transducers, and compare them.
2. Bi-frequency Driven Transducers
Fig.1 shows double layered transducers we
propose. As shown in Fig.1 (a), one consists of aployvinylidene fluoride (PVDF) layer and a leadzirconate titanate (PZT) layer. The PVDF film isboded on a surface of the PZT disc. Ultrasonicpulses are radiated from the aperture of 20 mm indiameter. Curvature radius of the transducer is 70
mm, thus the pulses are focused at center of thecurvature. The resonance frequency of the PZT discand the PVDF film are 2 MHz and 7 MHz,
respectively. Another is a double layered PZT thatis made by a sinter as an integral structure shown in
Fig.1 (b). The upper PZT is 600 μm thick and thelower PZT is 210 μm thick. Electrodes are formed
at top surface, bottom surface and between upperand lower PZTs. The PZT is cut out in an octagon
shape from a square PZT plate, 16 mm on a side.

An acoustic lens is bonded at the bottom surface,and radiated ultrasonic pulses are focused at
distance of 50 mm from the bottom surface of the
PZT.
(a) PZT with PVDF film(b) Double layered PZT

20 mm

16 mm

Outer shell
PZT

PZT
600 μmPVDF

Acoustic lens

210 μm

30 mm

70 mm

50 mm

Focal point
50 mm
Measurement area
20 mm

Fig.1 Configuration of the proposed transducers.
(a) PZT with PVDF film(b) Double layered PZT

3. Multi-frequency Beam Measurements
We measure multi-frequency ultrasonicbeams formed by the bi-frequency driven
transducers. Ultrasonic signals of 2 MHz and 8
MHz are generated by a digital-to-analog converter
and input to the transducers. The ultrasonic waves
radiated from the transducers are detected with aneedle type hydrophone (Force Institute) moving ina range of 20 mm by 1 mm steps in the radial
direction and a range of 50 mm by 2 mm steps in
the axial direction as shown in Fig.1, and sampled
by an 8 bit digital oscilloscope (LeCroy 9370CL).
Rate of the analog-to-digital conversion is 50 MS/s.
In one measurement, 5000 points sampled data are
obtained. To improve S/N ratio, we perform 64
times average on the oscilloscope. Sound pressurelevels of the each frequency components (f1, f2, f3, f4,f5) are calculated by fast Fourier transform (FFT).

Beam profile @ 2.0MHz
-10

180

0

160

10

30

40

50

60

70

80

Beam profile @ 4.0MHz

-10

180

0
10

140

160
30

40

50

60

70

80

Beam profile @ 6.0MHz

140

-10

180

0

160

10

30

40

50

60

70

80

Beam profile @ 8.0MHz

140

-10

180

0

160

10

30

40

50

60

70

80

Beam profile @ 10.0MHz

-10

180

0
10

140

160
30

40

50

60

70

80

140

(b)

Position [mm] Position [mm] Position [mm] Position [mm] Position [mm]Position [mm] Position [mm] Position [mm] Position [mm] Position [mm](a)Beam profile @ 2.0MHz

-10

180

0
10

160
30

40

50

60

70

80

Beam profile @ 4.0MHz

-10

180

0
10

160
30

40

50

60

70

80

Beam profile @ 6.0MHz

-10

160
30

40

50

60

70

80

Beam profile @ 8.0MHz

-10

160
30

40

50

60

70

80

Beam profile @ 10.0MHz

-10

140
180

0
10

140
180

0
10

140
180

0
10

140

160
30

40

50

60

70

80

140

Position [mm]Position [mm]Fig.2 Multi-frequency ultrasonic beams.
(a) PZT with PVDF film(b) Double layered PZT

4. Results and Discussion

Acknowledgment

Beam profile of each frequency radiatedfrom the bi-frequency driven PZT with PVDF filmtransducer is shown in Fig.2 (a). Frequency
components 2 MHz and 8 MHz are applied to the
PZT layer and PVDF layer, respectively. Similarly,
Fig.2 (b) shows results of the double layered PZTtransducer. Frequency components 2 MHz and 8
MHz are applied to the top electrode and theintermediate electrode, respectively. The bottom
one is common and set to grand.

This work was in part supported by KAKENHI(20300181).

Multi-frequency ultrasonic beams are formed on theboth results. In addition, the secondary waves
increase through the propagation. From the former
result, the beams are focused at the designed
position, and its width is narrow compared to thelatter result.

5. Conclusion
We proposed two different structure oftransducer that can transmit two frequency
ultrasonic pulses, and confirmed multi-frequency
beams generation by the transducer.

References
1. P.A. Magnin, O.T. Vonramm and F.L. Thurstone:
Ultrason. Imaging 4 (1982) 267.
2. I. Akiyama, H. Yamamoto, G. Ohashi, and A.
Ohya: Proc. IEEE Ultrasonics Symp. (2003)
1642.
3. I. Akiyama, H. Yamamoto, G. Ohashi, and A.
Ohya: Proc. 18th Int. Cong. Acoustics (2004)
163.
4. I. Akiyama, H. Yamamoto, G. Ohashi, and A.
Ohya: Acoustical Imaging 27 (2004) 651.
5. I. Akiyama, A. Ohya and S. Saito: Jpn. J. Appl.
Phys. 44 (2005) 4631.
6. I. Akiyama, S. Saito, and A. Ohya: Proc.
Symp.Ultrasonic.Electronics (2006) 141
7.I. Akiyama, S. Saito, and A. Ohya: J. Acoust. Soc.
Am. 120 (2006) 3026.
8. I. Akiyama, S. Saito, and A. Ohya: J. Med.
Ultrasonics 33 (2006) 71.

2P7b-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 295- 296
11-13 November, 2008

High-Amplitude and Long-Burst Pulse Transmission
Array Probe for Phase-Conversion Molecular Imaging
超音波分子イメージングのための高出力アレイプローブ
Takashi Azuma1†, Shiho Sonoda1, Ken-ichi Kawabata1 and Shin-ichiro Umemura2(1 Hitachi Central Research Laboratory; 2Facult. Eng., Tohoku Univ.)
東隆 1‡，薗田志保 1, 川畑健一 1，梅村晋一郎 2 （1 日立中研; 2 東北大 工）

1. Introduction
In phase-conversion ultrasonic molecularimaging [1], tissue-selective nano-droplets areconverted to contrast microbubbles by using higher
power ultrasound than that transmitted from a
conventional imaging array. Developing wideband
imaging arrays capable of phase-conversion
ultrasonic molecular imaging is useful since many
developed imaging sequences will be available
immediately after phase-conversion. Since thesensitivity of an array decreases as a result of the
breakdown
afterthetransmissionofphase-conversion ultrasonic molecular imaging, thelimitations of duration and amplitude need to be
overcome before an array for a phase-conversion
ultrasonic molecular imaging can be used. We
carried out various experiments and numericalsimulations to investigate the breakdown process.
In our previous study, a conventional arrayusing two PZT layers was broken after driving with
16 cycle pulses at 50 V caused. In this study, wemeasured breakdown conditions and breakdown
process of an imaging array in cooling condition. By
chnaging thermal boundary condition, it is expectedthat the thermal effect to breakdown process will beclear, and cooling effect to increase the limitation oftransmission ultrasound energy.
2. Material and method
We measured the electric impedances byusing a 4294A impedance analyzer (agilent)
and the round trip response of array elements
in an imaging array, whose center frequency is
7.5MHz, by using 5900PR pulser-receiver(panametrics) after high-amplitude and long
burst transmission. These results werecompared with the impedance and waveform
calculated by PZFlex, a finite element code, byassuming several different ways of breakdown.

-----------------------------------------------------------takashi.azuma.sa@hitachi.com

Fig.1
3.

Experimental setup

Results and discussions

Breakdowns of the array occurred after drivingwith 100 cycle pulses at 160 V. This single PZTlayer array could transmit higher power than two
PZT layer array before breakdown. Mechanical Q
values were increased with duration length during
this breakdown process as shown in Fig.2 and Fig.3.
Fig.2 shows results of impedance measurements
and Fig.3 shows results of round-trip response.
Fig.4 shows cooling of backing layer of transducer
array improved the limitation of transmission
energy from the transducer array. The experimental
result was consistent with the simulation result
assuming the peeling of the adhesive between PZTand the matching layer.
These results indicated that suppressing increasesintemperatureisalsoessential
forphase-conversion ultrasonic molecular imaging
using this improved array. Our simulation study has
already showed that a new transducer structure thatuses a heat conducting acoustic isolation layer on ametal block that was designed to inhibit this type of
breakdown while maintaining the wide bandwidth
required for imaging. Experimental results of thethermalbreakdown
after
phase-conversion
ultrasonic molecular imaging transmission from our
proposed structure probe will also be discussed.

Fig.2 electric impedance after 120V
driving. Numbers in the graph indicate
cycle numbers of driving burst waves.

phase-conversion
imaging.

ultrasonicmolecular

Fig.4 Sensitivity change of
responses caused by breakdown

round-trip

forAcknowledgment
Part of this work was supported by the New
Energy and Industrial Technology Development
Organization, Japan.
References
1. K. Kawabata, et al, IEEE Ultrason. Symp.
(2006) 517-520.

2. T. Azuma, et al, IEEE Ultrason. Symp.
(2006) 836-839.

Fig.3 Round-trip responses after 120V
driving. Numbers in the graph indicate
cycle numbers of driving burst waves.
4.

Conclusion

To prevent the peeling between matching layer
and PZT, heat conductance around PZT should be
improved. These experimental results indicate thatthe cooling effect improve the limitation oftransmission energy. These results also suggest that
improvement of heat conductance in a transducer
array using acoustic isolation layer will be useful2P7b-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 297- 298
11-13 November, 2008

Comparison of sound pressure distribution analysis withscale up experiment for small ultrasonic acoustic lens probe

Fumitaka Naitou1‡ Sayuri Matsumoto2, Mari Takahashi1, Takenobu Tsuchiya1 andNobuyuki Endoh1 (1Facult. Eng., Kanagawa Univ. , 2PARI)
1‡

2

1. Introduction
Many researchers are studying about
underwater ultrasonic high–resolution imaging
system. Authors have studied about thecharacteristics of convergence field of acoustic lensfor developing the underwater image system1-5). In
this study, we propose a small ultrasonic probe
composed with an acoustical lens for diagnosys andtherapy. The lens is designed by ray theory, andeffective diameter of the acoustical lens is 40mm.
We measured the characteristic of convergence fieldof acoustical lens in water tank. Size of lens is 4
times to final ultrasonic probe because of
preliminary study. And, we analysis acoustic fieldby FDTD method

1

1

1

1

,2

property. A virtual sound source was used for
reduction of calculation time. The distance between
virtual sound source and the first plane of lens is
40mm. The configuration of the virtual soundsource is circle of 660mm in curvature. It was
assumed that a burst-pulse of 10cycle at 2.0MHz
was radiated from virtual sound source.
Function generator

PC

XYZ stage

OscilloscopePower AMP

Pre AMP700 [mm]

2. Experimental setup and analysis modelZ

Figure 1 shows measuring system to obtain
convergence field of acoustical lens. The distance
between sound source and center of acoustic lens is
700mm. A burst-pulse of 10 cycles at 2.0MHz isradiated from the transducer whose diameter is
10mm and center frequency is 2.0MHz. The soundfield distribution behind the lens was measured by ahydrophone whose diameter is 0.6mm. Diameterand effective diameter of the lens is 58mm and
40mm, and first plane of lens is flat. Material oflens was acrylic resin. Acoustic refraction index ofacrylic is 0.53, and theoretical values of focal pointis 291.3mm from the first lens plane. The asphericsurface equation of 2nd lens plane is shown in Eq.
(1) The lens was fixed by lens holder.

X B 2 (Y ) =Y 2 /(136 .5) 2
1 + 1 − (1 + ( −0.5597 ))Y 2 /(136 .5) 2

Figure 2 shows analysis model to calculate
convergence field by FDTD method in cylindricalcoordination
using
symmetricalproperty.
Calculated sound fields by 2DFDTD do notcoincide with that of actual 3D lens. However, we
can get result of similar to three dimension analysis
by using cylindrical coordination using symmetricalY

Hydrophone
Acoustic lensTransducer

X

Fig. 1

Block diagram of measurement

z

x

y
x
500mm
Center axis

y
40mm

Lens

60mm

Lens holder
Absorber layer
Virtual sound source
Fig.2 Calculation model for FDTD simulation

E-mail ; r200770074yx@kanagawa-u.ac.jp

4.

Conclusion

Normalized amplitude [dB]

3. Result
On-axis sound pressure of measurement andanalysis result are shown in Fig.3 Comparison of
measurement to analysis results, measured
minimum value positions agreed well with analysis
results. Focal point of measurement and analysis is316mm and 310mm. Measurement and analysis
beam pattern of transverse axis of focal point are
shown in Fig.4. In the graph, beam width and beam
pattern are about the same. Sound field distribution
with cross section for axial distance in focal point
are shown in Fig. 5. We can see that measurement
and analysis result are convergence at the center.
Comparison of characteristics of lens between
experimental results and analysis results is shown in
Table 1. All graphs are normalized by focal pointsound pressure. Beam width is range of 0dB to
-3dB.

0
-2
-4

Experiment
Analysis

-6
-8
-10
-12
100

0

measurement

analysis

Focal point

316

310

Beam width

5.5

5.6

Acknowledgments
This study was partly sponsored by High-TechResearch Center Project from Kanagawa University
and the Ministry of Education, Culture, Sports,
Science and Technology, Japan 2007, Grand-in-Aid
for Scientific Research (20500429) in 2008 and2009.

On-axis sound pressure

-10
-15
-20
-25
-30
-20

Comparison of characteristics of lensbetween experimental results andanalysis results

450

Experiment
Analysis-5

We designed acoustic lens for small
ultrasonic prove, and measured and calculated
convergence field by the acoustic lens. Comparison
between measurement and analysis result, it wasalmost the same. And beam pattern of transverse
axis of focal point too. In future work, we will
research incident angle dependency of convergence
field of acoustic lens. Therefore, we will besimulating 3DFDTD of Cartesian coordinate system
without cylindrical coordinate system.
Table 1150 200 250 300 350 400
Axial distance X from lens first plane [mm]Fig. 3
Normalized amplitude [dB]

Calculated step size of in analytic area is 0.0375mm.
Sound velocity of water was calculated by
Greenspan’s equation at 18.0 deg. C, and soundvelocity of lens was reported in previous work6).
The lens holder is considered a rigid body.

Fig. 4

Fig. 5-10
0
10Transverse distance Y(r)[mm]
Beam pattern of focal point

20(a)Measurement(b)Analysis
Sound field distribution with cross section
for axial distance in focal point

References
1) S. Matsumoto, T. Tsuchiya, T. Anada and N.
Endoh : Proc. of European Conf. on Underwater
Acoustics, 2006, p.57.
2) S.Matsumoto H.Takeyama T.Tsutiya T.Anadaand N.Endoh : Proc. of Meeting of the Marine
Acoustics Society of Japan, 2007, p.57.
3) S.Matumoto,Y.Shin,T.tsuchiya,T.Anada,N.Endohand H.takeyama : USE2007 28 (2007)479.
4 F.Naitou S.Matsumoto Y.Shin T.Tsutiya
T.Anada and N.Endoh : Proc. of Meeting of the
Marine Acoustics Society of Japan, 2008, p.33.
5) Y.Shin S.Matsumoto T.Tsutiya T.Anada andN.Endoh : Proc. of Meeting of the Marine
Acoustics Society of Japan, 2007, p.25

2P7b-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 299- 300
11-13 November, 2008

Effect of edge mode resonance on directivity of small ultrasoundprobe fabricated with Lead Zirconate Titanate polycrystalline
film deposited by hydrothermal method
水熱合成法による PZT 多結晶膜を用いた小型超音波プローブの指向性に対するエッジモード共振の影響
Tomohito Hasegawa1†, Minoru Kuribayashi Kurosawa1 and Shinichi Takeuchi 2(1 Tokyo Tech.; 2TUY.)†長谷川智仁 1 ，黒澤実 1，竹内真一 2 （1 東工大 総理工; 2 桐蔭大 医工）

1. Introduction
Recently, miniature and high-frequency
ultrasound probes are widely having studied for
medical applications. Piezoelectric ceramics or
piezoelectric polymer films are used as
piezoelectric materials for the miniature
high-frequency ultrasound probes. Piezoelectric
polymer films show wide-band frequency
characteristics but have the problem of lowtransmission sensitivity. Ultrasound probes using
piezoelectric ceramics show high transmission
sensitivity. However, piezoelectric ceramics arebrittle, and the probe using them has narrow-band
frequency characteristics.
We reported the fabrication of needle-typeminiature hydrophones and ultrasound transducers
usinghydrothermallysynthesized
PZT
polycrystalline films[1][2]. It was confirmed thatthese films had wide-band frequency characteristics
with sensitivities in the megahertz band. It is thus
thought that these films can be used to for miniatureultrasound probes with wide-frequency bandcharacteristics. In the last report, the fabrication
methods of a miniature ultrasound probe and thetransmission and reception characteristics were
evaluated [3]. Here, we report the results of ourmeasurement of the probe’s reception andtransmission directivity.
2. Experiment method
The directivity of the miniature ultrasonicprobe was measured in a water tank. Schematic
diagram of the reception directivity measurement
method (a) and the transmission directivity (b) are
drawn in Fig. 1. The input signal to a transmitterwas 15 cycles of burst wave. The burst wave wasobtained by a function generator and a power
amplifier; 200 mV0-P output signal from thefunction generator was amplified by 55 dB using
the power amplifier. The received signal was
amplified using a pre-amplifier in a pulser-receiver,†tomohito.hasegawa@ip.titech.ac.jp

and then measured with a oscilloscope. Directivity
was measured from 90 to –90 degrees at intervals of
2 degrees. The directivity was measured at thefrequencies of 5, 10, 15, and 20 MHz. The distance
between the transmitter and the receiver was kept
far enough to maintain the far field condition. The
experimental results were compared with thedirectivity function calculated from far fieldradiation patter of a circular piston.
A. Directivity measurement of reception
The effective element diameter of theultrasound probe of the sound source was 6.35 mm,
and center frequency was 15 MHz. The miniatureultrasound probe and the PVDF hydrophone for acomparison were used for receiving. The diameterof each effective element was 0.6 mm. The distancefrom an acoustic radiation surface to the probe was
150 mm. The probe was fixed to the theta axis, anddirectivity was measured by measuring the voltage
while rotating the theta axis centering around asound reception surface.
B. Directivity transmission measurement
A miniature ultrasound probe with aneffective element diameter of 0.6 mm was used forthe sound source. The PVDF hydrophone was used
for reception. The distance from the acoustic
radiation surface to the PVDF hydrophone was 15
mm. The miniature ultrasound probe was fixed tothe theta axis, and directivity was measured bymeasuring the voltage while rotating the theta axis
centering around an acoustic radiation surface.

Fig. 1

Directive measurement system

5MHz
10MHz
15MHz
20MHz

1
0.8
0.6
0.4
0.2
0
-100

-50

0
50
θ [deg]Normalize Voltage

1
0.8
0.6

5MHz
10MHz
15MHz
20MHz

0.4
0.2
0
-100

-50

0
θ [deg]50

100

Fig. 3
Transmission directivity of miniatureultrasound probe

Normalize Voltage

1.2

5MHz
10MHz
15MHz
20MHz

1
0.8
0.6
0.4
0.2
0
-100

-50

0
θ [deg]50

100

Fig. 4
Receivingultrasound probe

directivityofminiature

4.

Results

The transmission and the receiving directivity
theoretical value are shown in Fig. 2. The
transmission directivity of the miniature ultrasoundprobe is shown in Fig. 3.

5MHz
10MHz
15MHz
20MHz

1
0.8
0.6
0.4
0.2
0
-100

100

Fig. 2 Theory value of transmission and reception
directivity

1.2

1.2
Normalize Voltage

Normalize Voltage

1.2

Fig. 5-50

0θ [deg]50

100Receiving directivity of PVDF hydrophone

The receiving directivity of the miniatureultrasound probe and the PVDF hydrophone isshown in Figs.4 and 5. Except for that at 5 MHz,the experimental reception directivity was similar to
the theoretical experimental values, i.e., thoseobtained with the PVDF hydrophone or with theminiature ultrasound probe. At 5 MHz, measured
directivity was sharper than that of the theoreticalvalue. Likewise, in transmission directivity, thetheoretical and experimental values were similar toeach other except at 5 MHz, at which main
directivity was low.
5.

Conclusion

As for the directivity of the miniatureultrasound probe, the theoretical value and theexperimental value were in good agreement for
both reception and transmission at 10, 15, and 20
MHz. However, at 5 MHz, the theoretical value andthe experimental value differed greatly in bothtransmission and reception. This can be attributed
to the effect of the resonance mode of the diameter
direction; namely, edge mode. In future works, thevibrational distribution of the end surface of aminiature ultrasound probe is scheduled to bemeasured with LDV.
Acknowledgment
This work was supported by a Grant-in-Aid for Japan
Society for the Promotion of Science Fellows.
References
1. M. Ishikawa, M. Kurosawa, E. Akito, and S.
Takeuchi : Jpn. J. Appl. Phys. 44 (2005) 4342.
2. H. Kitsunai, N. Kawashima, S. Takeuchi, M.
Ishikawa, M. Kurosawa, E. Odaira : Jpn. J. Appl.
Phys. 45 (2006) 4688.
3. T. Hasegawa, H. Kitsunai, A. Endo, N. Kawashima,
S. Takeuchi, M. Ishikawa, and M. K. Kurosawa :Jpn. J. Appl. Phys. 46 (2007) 4801.

2P7b-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 301- 302
11-13 November, 2008

Mechanical Properties of Low Attenuation Silicone Rubber Acoustic Lens
Material Doped with Zinc Oxide for Medical Echo Probe
酸化亜鉛を添加したシリコーンゴム製低減衰音響レンズの機械強度特性
Noriko Yamamoto1†, Yohachi Yamashita2, and Kazuhiro Itsumi1 (1Corporate Research and Development
Center, Toshiba Corp., 2Toshiba Research Consulting Corp.)
山本紀子1†，山下洋八2，逸見和弘1 （1（株）東芝

1.

Introduction
Silicone (Q) rubber has been the predominant
acoustic lens material for the medical array probe
application since 19701) because it is safe to use
for the human body, has a suitable sound velocity(c) (c~ 1000 m/s), and a reasonably low α (α~ 0.3
dBּmm–1ּMHz–1). However, the acoustic
impdance (Z) of pure Q rubber is approximately
0.97 × 106 kgּm–2ּs–1, which is considerably
different from the Z of human tissue (Z = 1.5 ×
106 kgּm–2ּs–1) at 37 oC. Therefore, to obtain the
Z of Q rubber close to that of human tissue, SiO2
powder has been doped into the Q rubber. Since
SiO2 has a low density (ρ), 2.2 × 103 kgּm－3,
dopant contents 35 vol% in Q rubber arenecessary for obtaining a Z of higher than 1.4 ×
103 kgּm－3. As a result, SiO2 -doped Q rubbershows large α > 0.9 dBּmm–1ּMHz–1 and poor
mechnical properties.
Recently, the authors have reported theacoustic properties of high temperature
vulcanization (HTV) Q rubber doped with high-ρ
dopants (ρ = 9.2), Yb2O3. The HTV Q rubberwith Yb2O3 nanopowder dopant having an
average particle size of 8 nm shows the low α,
appropriate Z, and high mechanical properties.
However, the rubber has low mechanical tearstrength less than 30 N/mm for practicalapplication,andbio-compatibility
was
uncertain.2,3) The ZnO has also high-ρ (ρ = 5.6),
and is stable procurement and bio-compatible
material. In this report, the effect on acoustic andmechanical properties of ZnO-doped HTV Q
rubber has been studied to develop a reliablelow-α lens material for medical array probe
applications.
2. Measurements and Results
2.1 Acoustic and mechanical properties
The ZnO powder of the particle size of 30 nm
was added to the millable type HTV Q rubber,3)
which was used as the base material in this study.
To realize several Z values of lens, the ZnO
powder dopant contents in Q rubber were varied.
Table I lists the acoustic and mechanical

研究開発センター，2東芝リサーチコンサルティング（株））

properties of the base HTV Q rubber, two Z typesof ZnO-doped HTV Q rubbers (sample 1 and 2),
and the conventional lens material Q rubber(Ref.). The base HTV Q rubber material contains
about 10 vol% of 20 nm-particle-size of fumed
SiO2 powder. Thus, ZnO powder vol% is shown
without SiO2 in Table I. All the acoustic
properties were measured at 37 oC, and eachmechanical property was measured at room
temperature in according with JIS K6253, K6252
and K6264-2. Both ZnO-doped samples had
lower attenuation coefficient α than theconventional lens rubber. Tear strengths andelongation of ZnO-doped samples were about 3
times bigger than those of the conventionalrubber. The rubber, which has high tear strengthand elongation generally shows strong rub
resistance. At Table I, this tendency was also
appeared in the abrasion loss; ZnO-doped
samples indicated about 1/3 compared to that of
the conventional rubber.
Table I. Acoustic and mechanical properties of
HTV Q rubbers.
Base
SiO2

1
2
Ref.
†
†
ZnO ZnO SiO2

10

12.4

15.4

23

Rubber density (g/cm ) 1.09

1.73
839

1.4
1039

1.46

1.45

SampleDopantDopant content (vol%)3

Acoustic velocity (m/s)*

955

1.61
849

Acoustic impedance Z *－2 －1( × 106 kg・m ･s )

1.04

1.38

Tear strength (N/mm)
Elongation (%)
Abrasion Loss (g)
o

24
46
43
16
430
590
560
170
0.034 0.072 0.125 0.362†*Measured at 37 C / SiO2 is also included in the base Q rubber

2.2 Rubbing scanning test
The ZnO-doped rubber sample 2 andconventional lens rubber were shaped in acoustic
lens for use of rubbing scanning experiment.
Using the abrasion tester (the color fastness toabrasion test machine according as JIS L0849),
fixture part was modified and two pieces of lens
shaped sample were settled. Figure 1 illustrates
the motion of the abrasion tester. Settled two
samples were same type and were rubbed same
direction as ultrasonic diagnostic scanning. On
the stage, 15-mm-width waterproof sandpaper(AWA P600) was placed. Ultrasonic diagnostic
jelly (SONO JELLY (M), Toshiba Medical
Supply Co., LTD.) was applied on the sandpaperand samples. The abrasion test was executed 800
times of back and forth motion; each 200 times,
SONO JELLY was added, and each 400 times,
sandpaper was renewed. The abrasion loss rates
on the initial sample weight showed 0.83% in
ZnO-doped sample 2 and 1.68% in conventionalrubber. Figure 2 shows the cross-section profilesof the lens shaped samples. The ZnO-doped
sample kept round lens shape even after therubbing test, in contract, the conventional rubber
was planed. Therefore, using the ZnO-doped
HTV Q rubber predicts a long-life acoustic lens.
Rotation center
（fix）

Load
（485 g）

SamplesMove in parallelFig. 1. Motion of abrasion tester.
SampleSample 2Ref.
(a) Before rubbing test
Hight (arb. unit)

Hight (arb. unit)(a) Before rubbing test

Width(b) After rubbing test

Hight (arb. unit)

Hight (arb. unit)

Width(b) After rubbing test

Width

Width

Fig. 2. Lens profiles of (left) ZnO-doped rubberand (right) conventional rubber (a) beforeand (b) after rubbing scanning test.
3.

(a)

5.0 μm(b)

5.0 μmFig. 3. SEM images of (a) ZnO-doped rubber (×5000) and (b) conventional rubber (× 2000).
4.

Pendulum

Sandpaper andjelly on the stage

The additive ZnO powder was in spherical shape,
because of that caused high and uniform
dispersibility in the Q rubber. The rubber strengthis decided by how much of the breaking origins
in the material. Because of ZnO-doped rubber has
fewer pores and agglomerations, and the shape of
ZnO powder is spherical, there is little chance of
breaking origination. Further, ZnO is also used as
vulcanization accelerator so that made the HTV
Q rubber mechanical properties more strength.

Discussion
Figure 3 shows SEM microstructures of
ZnO-doped HTV Q rubber (a) and conventionalrubber(b).
Neither
large
pores
nor
agglomerations were seen in ZnO-doped rubber.

Conclusions
The
ZnO-doped
hightemperature
vulcanization (HTV) Q rubbers for acoustic lensmaterials were investigated. Their acoustic andmechanical properties were compared to evaluate
their use as an acoustic lens material for medical
ultrasonic probe application and the following
results were obtained.
(1) Comparedwith conventional rubber,
ZnO-doped HTV Q rubber showed 3 times
higher tear strength and elongation andabrasion loss was 1/3.
(2) The rubbing scanning test evidenced that
ZnO-doped rubber lens has excellent rub
resistance.
(3) Spherical shaped powder ZnO and its effects
of vulcanization acceleration to the baserubber contribute high mechanical strength of
ZnO-doped rubber.
References
1. K. Iinuma and M. Hashimoto: Proc. 26th
Conf. Medical Ultrasonics, Tokyo, 1974, Jpn.
J. Med. Ultrason., 28 (1974) Suppl. 26, p.
119 [in Japanese].
2. Y. Yamashita, Y. Hosono, N. Yamamoto, and
K. Itsumi: Jpn. J. Appl. Phys. 46 (2007)
L851.
3. Y. Yamashita, Y. Hosono, N. Yamamoto, and
K. Itsumi: Jpn. J. Appl. Phys. 47 (2008)4132.

2P8-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 303- 304
11-13 November, 2008

A novel cleaning equipment using ultrasonic waveguide mode
導波路管型超音波洗浄機用振動子の試作
Kazunari Suzuki1,2‡ , Ki Han1 , Shoichi Okano1 , Jyunichiro Soejima1
and Yoshikazu Koike2 (1KAIJO CO., LTD.; 2Facult. Eng.,Shibaura Inst.of Tech.)
鈴木一成 1,2‡，潘毅 1，岡野勝一 1 ，副島潤一郎 1，小池義和 2（1 カイジョー; 2 芝浦工大 工）

1. Introduction
There is a great demand for ultrasonic cleaning,
Inlet
Packing
not only in the advanced semiconductor/FPD
Substrate
Case PZT
Reflection nozzle
cleaning process but also in the substrates for HDD
Wave guideor photovoltaic manufacturing process. The authors To Generator
φ36
φ6×φ4
have been investigating a spouting megasoniccleaning equipment (Spot type shower) 1,2). This
Outletequipment is possible to installed in the piece byθPart Apiece type cleaner. However, distance between
66
megasonic nozzle and substrate should be set up
within 20mm to obtain optimum cleaning effect.
Therefore, it takes a lot of spaces on substrate to set
φ15
φ4
up the nozzle and arm.3) In this report, we proposeda novel cleaning equipment using ultrasonicwaveguide mode (we call MEGATUBE). By
Detail of part A
applying the input power to the PZT, ultrasonicunit : mmwave can be traveled along the waveguide. It is
possible to supply ultrasonic apart from PZT. We
Fig.1 Configuration of the waveguide typeshowed the prototype transducer using waveguide,transducer
and propagation characteristics were investigated.
Reflection nozzle

kz-suzuki@kaijo.co.jp

Waveguide (φ6×φ4)

φ15Sound pressure(norm.)

2. Transducer using ultrasonic waveguide mode
The transducer using a waveguide consists of a
PZT attached with a vibration plate, reflection
nozzle (SUS316L), and a waveguide (quartz) as
shown in Fig.1. These parts were installed in a caseand sealed by packing. Cleaning solution (DI wateror chemicals) is supplied from a case andthroughout the waveguide. Reflection nozzle has
been applied to the spot type shower.4) Ultrasonicwaves generate from PZT (vibration area is 15mm
in diameter) are reflected between PZT andreflection nozzle, waves are converged towards thecenter of the nozzle and emitted together withsolution flowing. A waveguide connected withreflection nozzle has a removable structure. We canselect the waveguide that has a different length or
bend shape according to the purpose.
We tried a simulation of wave propagation
using Cellular Automata.5) Fig.2 shows propagationin the waveguide filled with water. Ultrasonicwaves are generated from vibration area (φ15) at
950 kHz. Waves propagate in the waveguide have aperiodic waveguide mode. Wave data shows thesound pressure at center of Y-axis. Period of soundpressure along X-axis is under consideration.
------------------------------------------------------------

1
0.8
0.6
0.4
0.2
0
0

20

40
60
X direction [mm]

80

100

Fig.2 Propagation in the waveguide predicted by
Cellular Automata
3. Sound pressure measurement by hydrophone
Sound pressure was measured using a quartz rodhydrophone probe (Honda elec. HUS-5). As shownin Fig.3, cleaning solution (DI water) spouting fromwaveguide will reach at the hydrophone and output
voltage is measured by oscilloscope (Lecroy wave
Jet 354). Rectify processing and 30Hz low-passfilter was applied by PC to concern the change of
output voltage due to solution flowing. Ultrasonic
generator (KAIJO 28101) is connected to thetransducer and generate at 950 kHz. Flowing rate iscontrolled at 1L/min and dissolved O2 concentrationof DI water is at 7~8ppm.

0.4

センサー出力電圧（V)

0.3

D.I.Water

0.2
0.1
0.0
-0.1
-0.2
-0.3
-0.4
0.000

0.002

0.004

0.006

0.008

時間（sec.）To generator

Wave guide[P.C]
Averageprocessing

20mm

Transducer

Fig. 3 Schematic diagram of sound pressure
measurement using hydrophone probe

Output voltage [mV]

0.20
0.15
0.10
0.05
0.00

0

5

10 15 20 25
Output power [W]30

35

Fig. 4 Dependence on the output power at spot type0.20
Output voltage [mV]

4. Conclusion
We showed the prototype transducer using
waveguide, and propagation in waveguide predicted
by Cellular Automata has a continuous waveguidemode. At the sound pressure measurement usinghydrophone the output voltage decreases depend on
the length of waveguide, at 500mm in length, it
decreases in 41% against the spot type. The output
voltage is almost same depend on the angle ofwaveguide. Therefore, we can expect the stablecleaning effect when using waveguide which has abend shape.
References
1. H. Suzuki, K. Ichikawa and S. Takahashi : Kaijo
Technical Report. 9 (1999) p.8.
2. K. Suzuki : Kaijo Technical Report. 12 (2003)
p.33.
3. K. Suzuki, K. Han, S. Okano, J. Soejima and Y.
Koike : USE 2008 Symp. Ultrasonic Electronics.
(2008). [To be presented]
4. S. Takahashi : Official report of patent, No.
3256198 (2002)
5. T. Komatsuzaki, H. Sato, Y. Iwata and
S.Morishita : Transactions of JSCES(1999) Paper
No.19990017.
6. J. Saneyoshi, Y. Kikuchi, and O. Nomoto:
Ultrasonic technical handbook (1966) p.921[Oscilloscope]
Voltage
waveform

Probe

0.15
0.10

L

0.05
0.00

0

100

200

300

400

500

600

Length of wave guide [mm]Fig. 5 Dependence on the length of waveguide
0.20

Output voltage [mV]First, spot type transducer which has nowaveguide3) was evaluated. The output voltage ofhydrophone was measured changing the output
power of generator. As shown in Fig.4, the larger
output voltage could be obtained with the larger
output power, and output voltage becomes 0.17mV
at 30W.
Next, waveguide type transducer was evaluated.
The output voltage of hydrophone was measuredchanging the length of waveguide, and output
power is fixed at 30W. As shown in Fig.5, theoutput voltage decreases depend on the length ofwaveguide, and output voltage becomes 0.10mV at
500mm, it decreases in 41% against the spot type.
Between the length of 100mm and 500mm, output
voltage decreases in 42%. One of a factor in thisphenomenon is absorption of ultrasonic in water.
Coefficient of absorption in water is 25×10-3 at
1MHz,6) and decrease in distance 400mm is
calculated with 1%. Therefore, there is a great
different with measurement result. Influence ofdissolved gas in water or absorption of ultrasonic in
waveguide made of quartz should be concerned.
The output voltage of hydrophone was measuredchanging the bend angle of waveguide, waveguidelength is 200mm, bend radius is 60 mm, and output
power is fixed at 30W. As shown in Fig.6, theoutput voltage is almost same depend on the angleof waveguide, and obtained output voltage is
0.12mV approximately

0.15
0.10

θ
0.05
0.00

0

20

40

60

80

100

Bend angle [deg]Fig. 6 Dependence on the bend angle of waveguide

0.010

2P8-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 305- 306
11-13 November, 2008

Nucleation Enhancement of Al alloys
by High Intensity UltrasoundJeong IL Youn1‡, Byoung IL Kang, Beom Suk Han2 and Young Jig Kim1
( School of Advanced Materials Science and Engineering, Sungkyunkwan Univ.,2
Vehicles Research and Development, Korea Automotive Technology)
11.Introduction
Ultrasound is well known as a tool used in
medicine for fetal imaging, in underwater range
finding or in the non destructive testing of metals
for flaws. However, the ultrasound with highintensity energy could be used in melting andcasting process to obtain fine-grained ingot. In
order to obtain fine-grained microstructure, thenucleation frequency has to be increased and grain
growth must be restrained. Various processes, suchas rapid cooling, melts stirring, and inoculation,
have been used for obtaining fine grains. The highintensity ultrasound has been implied to increase
the nucleation frequency during solidification of
metal melts. It has been shown that the injection ofhigh intensity ultrasound vibration into aluminumalloy during its solidification can eliminate
columnar dendritic structure, refine the equiaxed
grains, and under some conditions, produce
globular non dendritic grains [1,2]. Mechanisms forgrain refinement under ultrasonic vibration havebeen proposed but they are still arguable [3]. In
addition, the process application of high intensity
ultrasound vibration for grain refinement of ingot
mainly has been focused on solidification orsemi-liquid region of metal alloy. However, in thisway, ultrasound injection for fine-grained ingot
could not be applied to normal casting processes, i.e.
sand casting, permanent mold casting, and die
casting.
In this study, high intensity ultrasound process, it
is named as Sono-processing, was tested as arefinement process of primary alpha and siliconphase in hypo- and hyper-eutectic Al-Si alloy, A356
and A390 alloy, respectively. The present
investigation attempts to evaluate the effect ofultrasound vibration on microstructure, which was
cast to be injected ultrasound vibration energy into
the full alloys melts.

Table I. Chemical composition of A356 and A390
aluminum alloy (mass%)
Element

A356

A390

Si

6.9

16.9

Cu

0.2

4.3

Mg

0.4

0.5

Mn

0.1

0.1

Fe

0.1

0.1

Al

Bal.

Bal.

Fig. 1 shows the ultrasound injection system of 20
kHz with the power output up to 840 W for metal
melts. The system comprised of an ultrasonic
generator, a transducer of PZT type, booster andradiator horn. The most important thing in thisapparatus was a cooling system for PZT transducer
which was not worked at high temperature. The
molten alloy injected ultrasound was poured into
the permanent mold heated at 150 oC and then,

2. Experimental procedure
1.Cooling air in, 2.PZT 3.Booster horn, 4.Radiator horn,

A356 and A390 aluminum alloys were cast in thelaboratory. The chemical composition for thesealloys is given in Table I.
-----------------------------------------------------------younj1@skku.edu

5.Cooling water out, 6.Cooling water in, 7.Elevator, 8.Melts,
9.Graphite crucible, 10.Electric resistance furnace

Fig. 1
Schematic diagram of apparatus forultrasound injection into metal melts

pouring temperature was about 700±10 oC and
750±10 oC at A356 and A390 alloy, respectively.

(a)

3. Results and discussions
The optical micrographs of the samples fromcastings made with and without high intensity
ultrasound injection into alloys melts are shown in
Fig. 2 and 3. The microstructure refinement,
especially primary alpha phase, could not be
achieved in A356 alloy with simply ultrasoundinjection into alloy melts as shown in Fig. 2 (a) and(b). However, the influence of ultrasound on the
microstructure in A390 alloy is very clear as shownin Fig. 3 (a) and (b). Primary silicon of A390 alloy
with ultrasound injection into melts was very small
and dispersed uniformly in alloy matrix. In previous
study, it has been reported that the microstructurerefinement could be achieved by ultrasoundvibration only during solidification of melts, andthere is no effect on nucleation enhancement by justmelts vibration [4]. The same result gets in thisexperiment on A356 alloy. Compared with A356
alloy, however, A390 alloy shows the nucleation
enhancement by ultrasound vibration of melts only.
Based on these experiments results, solute cluster
hypothesis could be suggested. Until now, themicrostructure refinement by ultrasound injection

(a)

(b)

Fig. 3 Microstructure of A390 alloy; (a) withoutand (b) with ultrasound injection for 10 min.
could be explained only in terms of break ofdendrite arms during solidification and/or formationof nuclei by cavitation effect. However, solutecluster hypothesis suggests that the microstructurerefinement can be achieved by uniformity of solutecluster in melts as a chemical composition, and in
result, nucleation enhancement can be promoted byhigh intensity ultrasound.
4. Conclusion(b)

The present investigation attempts to evaluate theeffect of ultrasound vibration on the microstructureof hypo- and hyper-eutectic Al-Si alloys. The
microstructure refinement could be achieved byultrasound injection into metal melts as a chemicalcomposition. The refinement mechanism could be
explained by solute cluster hypothesis.
References
1. X. Jian, T.T. Meek and Q. Han : Scripta Mater.
54 (2006) 893.
2. Y.L. Li and et al : Mat. Sci. and Eng. A. 487(2008) 518.
3. J. Campbell : Int. Met. Review. 2 (1981) 71
4. Y. Osawa and et al : J. JFS 71 (1999) 98

Fig. 2 Microstructure of A356 alloy; (a) withoutand (b) with ultrasound injection for 10 min.

2P8-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 307- 308
11-13 November, 2008

Ultrasonically Induced Enhancement in Treatment ofLivestock Waste Sludge
Jiho Park1, Young Uk Kim 1†, Jong-Sub Lee2, Mian Chen Wang3(1Dept. of Civil & Env.
Eng., Myongji Uni., 2Dept. of Civil & Env. Eng., Korea Uni., 3Dept. of Civil & Env.
Eng., The Pennsylvania State Uni.)

The effect of ultrasound on total mass, dewaterability, turbidity, and coliform counts of livestock waste
sludge was investigated. The study involved laboratory tests and pilot plant experiment under various test
conditions including sonication time, ultrasonic energy level, and sludge volume. Laboratory test results
showed that sonication caused a decrease in sludge particle size, capillary suction time, and coliform counts.
Pilot plant experiment results showed that ultrasonic treatment significantly improved dewaterability, andreduce the volume, mass, and water content of sludge.

KEYWORDS: ultrasound, sludge, livestock waste, sludge disposal, sludge dewaterability, pilot plant

The rapidly increasing quantities of sludge
produced in livestock waste treatment facilities
may cause serious and direct impacts on publichealth. Because the cost associated with sludge
handling and disposal is highly dependent on thevolume and water content of the sludge, there is agreat interest in developing techniques for
reducing sludge volume. A technique that hasreceived considerable attention is sonication. A
number of studies have investigated the beneficial
effect of treating the sludge with ultrasoundbefore the sludge reaches the digesting tank toincrease soluble Biochemical Oxygen Demand(BOD).1-2) There are also studies investigating theeffectiveness of ultrasound on the dewaterabilityof sewage sludge by changing the floc structuresand microorganism surface properties.3-4)
The primary focus of this study is toinvestigate the effectiveness of ultrasound inenhancing the dewaterability of sludge as a post treatment process. In addition to dewaterability,
the effect of sonication on coliform counts andcapillary suction time was investigated.
Meanwhile, pilot plant tests were performed toinvestigate the potential application of thelaboratory experimental findings.
The test sludge was obtained from atreatment plant of livestock waste in Kimpo,
Korea. After sampling from an anaerobic
digestion tank, the test sludge samples wereprepared at a constant solids concentration. The
sludge was ultrasonically treated in a bath-typeultrasonic processor(Chosun, Model CS-1000,
36×36×36(cm)) under various test conditions. The
1†E-mail: yukim@mju.ac.kr

piezo ceramic transducer of 50mm diameter and
85mm height was used to produce ultrasound thatwas tuned at 28kHz. The applied ultrasoundenergy level was expressed in terms of thespecific supplied energy parameter which isdefined as follows:
IUS =

P×t
Vol

(1)

In which, P is the consumed ultrasonicpower(kW), Vol is the total volume of the sludge
sample(liter) and t is the ultrasonic irradiationtime(minutes). During the test, the time required
for water coming out of sludge to travel a certain
distance through filter paper(whatman 17CHR)
was measured using a CST(capillary suction time)
tester. All measurements were done in triplicate
under the same conditions, and the average values
were used for the subsequent analysis.
The pilot plant experiment was performed
using the specially developed large scale
ultrasonic bath processor. The processor, shown in
Figure 1, had a diameter of 1m and a height ofalso 1m. The experiment was conducted using amaximum power of 6kW with 28kHz ultrasonicwave frequency, and the specific supplied energy
parameter(IUS) was maintained around 30. The
reason for the chosen value will be discussed in
the later. The test sludge was first treated withultrasound, and was then dewatered using acentrifuge machine. After dewatering, the mass,water content, and volume of the dewateredsludge were measured.

The pilot plant experiment shows
considerable difference in the total volume ofsludge both with and without sonication as
illustrated in Figure 4. These results indicate
clearly that ultrasonic energy reduces not only thevolume of sludge, but also its mass and watercontent.
Fig. 1. Large scale ultrasonic processor
Cake

Figure 2 shows the change in CST(capillarysuction time) with IUS. CST was measured toevaluate sludge dewatering behaviors according tochanges in particle size. CST indicates how fastsludge can release its water. Usually, a long CST
means a high cake specific resistance. In the
figure, a decrease in CST with increased IUS isclearly seen. Based on the definition of IUS, theresults indicate that CST reduction is influenced
not only by ultrasound power but sonication timeand sludge volume as well. The results also revealthat sludge flocs were both separated anddisintegrated by ultrasonic treatment, resulting in
the increased filterability.
100

CST(sec)

80
60
40
20
0
0

50

100

150

Without ultrasoundCentrifuge

W ασδσωω 77.1%
δσ1280mlVol
M

441.6gCake
Centrifuge

With ultrasoundWithultrasound

W

Vol

M

12.8%

57.8%

34%







W ωω 64.3%
Vol

540ml

M

291.6gW : water content
Vol : volume
M : mass

Fig. 4. Cake reduction due to ultrasound

The pilot plant experiment was conducted
to investigate potential field applications of theseresearch findings. In conclusion, ultrasonictreatment is a useful tool for enhancing sludge
dewaterability thereby reducing the amount ofsludge released from livestock waste treatment
facilities.
This study was gratefully supported by
Korea Research Foundation Grant (KRF – 2005
– 202 - D00504).
References

200

IUS

Fig. 2. Capillary suction time

Coliform count is a commonly - usedbacterial indicator to determine the sanitary
quality of food and water. Figure 3 shows thatcoliform counts decrease with increasing IUS at atrend resembling that of previous figures.
Coliform counts decrease drastically and remain
almost constant as ultrasonic energy increases.
Thus, in addition to dewaterability, ultrasound canalso affect the sanitary quality of livestock waste
sludge considerably.

Coliform counts / ml

3000
2500
300 Watts
600 Watts

2000
1500
1000
500
0
0

100

200

300

IUS

Fig. 3. Coliform counts vs. IUS

400

1.
2.
3.
4.
5.
6.

J. A. Müller: Wat. Sci. & Tech. 44(2001)
121.
U. Neis, K. Nickel and A. Tiehm: Wat. Sci.
& Tech. 42(2000) 73.
Y. Kim and B. Kim: Jpn. J. Appl. Phys.
42(2003) 5898.
Y. Kim, J. Ha, G. Kim and S. Na: Jpn. J.
Appl. Phys. 45(2006) 311.
L. H. Mikkelsen and K. Keiding: Wat. Res.
36(2002) 2451.
A. Tiehm, K. Nickel, M. Zellhorn, and U.
Neis: Wat. Res. 35(2001) 2003.

2P8-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 309- 310
11-13 November, 2008

Estimation of Sound Energy Distribution for the Design
Optimization of Large-Scale Sonoreactors
Younggyu Son1‡, Myunghee Lim1, Ik-Beom Park2, Mingcan Cui1, Jeehyeong Khim1†(1 Department of Civil, Environmental and Architectural Engineering, Korea
University; 2Gyeonggi-do Institute of Health and Environment)

1. Introduction

2. Materials and methods

Numerous cavitation events including theformation, oscillation and implosive collapse of
bubbles occur continuously an locally in
micro-scale as ultrasonic wave over 20 kHz travels
in the aqueous phase. It is believed extreme
conditions such as high temperature over several
thousand degrees Kelvin and high pressure over1000 atmospheres are formed inside cavitation
bubbles. During the oscillation and the collapse ofcavitation bubbles these severe conditions lead to
removals of organic pollutants related to pyrolysis
and radical oxidations inside bubbles and adjacentregions.
Many previous studies have shown that awide variety of organic pollutants including
chlorinated compounds, phenols, and endocrine
disrupting compounds can be effectively degradedusing ultrasound alone and combination with otheradvanced oxidation processes such as ultraviolet,
ozone, hydrogen peroxide and so on. The common
working volumes of sonoreactors which have beenreported in the literature are in small scale ranged toonly several hundred milliliters, related to probe
type and cup horn type. For the industrial
application of ultrasound, researches on large-scalesonoreactors were rarely done.
This present study was designed to evaluate
the performance of a large-scale sonoreactor undervarious conditions. The specific objectives of thisinvestigation were to quantify the sonochemical
reactions and to optimize the geometry ofsonoreactors.

The sonoreactor used in this study consistedof an acrylic reactor and an ultrasonic transducer
module (Mirae Ultrasonic Tech.) placed at thebottom. The transducer module contained nine PZTtransducers and could produce ultrasound of 35, 72,
100 and 170 kHz frequency. The maximum powerof the transducer module was 400 W. The reactor
was filled with distilled water of 60 L.

-----------------------------------------------------------hyeong@korea.ac.kr

Fig. 1 Schematic of the large- scale sonoreactor

An ultrasonic /megasonic cavitation meter(ppb pb-502) was used for the analysis of cavitationenergy in the sonoreactor. This instrument could
detect the collapse of the cavitation bubbles as they
imploded on the surface of a probe. As a result, it
could display the energy density of cavitation as aunit of W/cm2. The diameter of the probe was 5 cm.
When ultrasound is applied to an aqueous
potassium iodide (KI) solution, triiodide ion (I3-)
can be liberated from the iodine ion. The amount oftriiodine ion liberated can then be used for thequantification of a sonochemical reaction as
sonochemical efficiency (SE), as follows:

SE =

CI
PUS tUS / VI(1)

where CI is the liberated triode ion concentration,
PUS is the cavitation energy, tUS is the irradiation
time and VI is the aqueous volume. In this study, theconcentration of KI was 0.1 M, the irradiation timewas 10 min., and the amount of liberated iodine wasmeasured at 350 nm using a UV/VIS
spectrophotometer (Analyticjena SPECORD 40).
Hydrogen peroxide was measure using the KI
method.

Cavitation energy = − 0.0016 (input energy ) 2+ 1.4459 (input energy )(2)

3. Results
Cavitation energy was measured along theliquid height, which was irradiation distance. Fig. 2
shows cavitation energy distributions for 80, 160,
240 and 320 W of input electrical energy. Measured
cavitation energy decreased from at the position of
5 cm to the position of 10 cm. However cavitationenergy increased after 10 cm as the height of liquidincreased and then decreased again drastically nearliquid surface. No evidence of cavitation- energy
attenuation was not found here.

Fig. 3

Relationship between input electrical energy andmeasured cavitation energy for 35 kHz

Acknowledgements
This study is supported by the Ministry ofEnvironment, Republic of Korea as “The
Eco-technopia 21 project” (no. 061-081-042).

References

Fig. 2 Cavitation energy distributions for 80, 160, 240
and 320 W in the large-scale sonoreactor

Fig. 3 shows the relationship between averge
input electrical energy and average cavitationenergy for 35 kHz. The empirical relationships (eq.
2) was obtained using a quadratic curve fitting skill.
This was successfully achieved (R2 was 0.9969).

1. Y. G. Adewuyi, Ind. Eng. Chem. Res. 40 (2001)
4681.
2. L. H. Thompson and L. K. Doraiswamy, Ind. Eng.
Chem. Res. 38 (1999) 1215.
3. T. J. Mason and J. P. Lorimer, Applied
Sonochemistry-The Uses of Power Ultrasound in
Chemistry and Processing, Wiley-VCH Verlag
GmbH, Weinheim, 2002.
4. T. G. Leighton, The Acoustic Bubble, Academic
Press, London, 1994.
5. Y. Asakura, T. Nkshida, T. Matsuoka and S. Koda
Ultrason. Sonochem. 15 (2008) 244.

2P8-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 311- 312
11-13 November, 2008

Extraction of Metal Species from Contaminated Soils Utilizing Supercritical
CO2 and UltrasoundIk B. Park, Younggyu Son (Korea University), Il S. Song, Kyung H. Na, Jongchan Kim (Gyeonggi-do
Institute of Health and Environment) and Jeehyeong Khim† (Korea University)
1. Introduction
Supercritical Fluid Extraction (SFE) is the processof separating the extractant from the sample matrix
using supercritical fluids such as carbon dioxide(CO2) etc., as the extracting solvent. Recently,
supercritical fluids comprising a chelating agent
have been proposed for chelation and dissolution of
metals and metal oxides without the use of eitherorganic solvents or aqueous solutions [1]. Currently
the most commonly used supercritical fluid is CO2
due to its low critical parameters (31.1 ℃, 7.4 MPa),high diffusivity, non-toxicity and low viscosity.
Though supercritical CO2 has been applied
successfully for the extraction of organic
compounds in industry, the direct extraction of
metal ions using pure supercritical CO2 was foundto be inefficient, due to the charge neutralization
requirement and the weak solute-solvent interaction[2]. In order for heavy metals to be dissolved in
CO2, the metals must be present as electricallyneutral complexes. If a suitable chelating agent ischosen, a CO2–soluble organic chelating agent willproduce a metal complex that can be extracted
easily into supercritical CO2 from sample matrices[3]. This chelation-SFE might be a promisingtechnology for the treatment of metal-contaminatedsoil materials. Moreover, ultrasound has been
widely applied in chemical, pharmaceutical,
medical and food industries etc., and enhances therate and the efficiency of the extraction processusing ultrasound in combination with SFE [4]. The
main purpose of this study is to identify andevaluate the extraction efficiency of metal species
for contaminated soils using supercritical CO2, achelating agent and ultrasound.

Fig. 1 Chemical structure of the chelating agent.
Soil samples

The soil samples were commercially available sandobtained from Joomoonjin, Republic of Korea, with
0.5 wt% of organic content and was sieved througha 1 mm sized mesh. An ICP-spiking solution(AccuStandard, Inc., USA), containing 15 metal
species of Sb, As, Ba, Be, Cd, Cr, Co, Cu, Pb, Ni,
Se, Ag, Tl, and V, was spiked into the soil material
and was mechanically mixed in order to achieve ahomogeneous state. It was then aged for 7 days atroom temperature.
Chelation-SFE-ultrasound system① CO2 cylinder ② condenser ③ syringe pump ④ heating coil ⑤
pressure gauge ⑥ ultrasonic power generator ⑦ ultrasonic transducer⑧ high-pressure extractor ⑨ temperature controller ⑩ separator

Fig. 2 Schematic diagram of the experimental system.

2. Materials and Methods
Chelating agent

The chelating agent used in this study is Cyanex
272, as shown in Fig. 1, which contains 85% bis(2,4,4-trimethylpentyl)phosphinic acid, and was obtained
from Cytec Inc., Canada.
-----------------------------------------------------------hyeong@korea.ac.kr

Fig. 3 Structure of the high pressure extractor.

3. Experimental Results and Conclusion
The soil samples were digested for 20 min in a
microwave digester (MARS-5, CEM) with HNO3(70%) at a temperature of 180 ℃. The subsequent
solutions were analyzed by the ICP-AES(inductively coupled plasma-atomic emission
spectrometer, Vista-pro, Varian Inc., USA). The
concentrations of the metal species for original andspiked soil samples were measured as shown in
Table 1.
Table 1 Conc. of metal species for original and spiked soil
Metalspecies
Ag
As
Ba
Be
Cd
Co
Cr
Cu
Ni
Pb
Sb
Se
TI
V

Conc. of original soil
(mg/kg)
0.434
0.440
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
0.510
1.066
N.D.
N.D.
0.112

Conc. of spiked soil
(mg/kg)4.798
14.81886.1107.738
15.30231.29883.72877.35240.25431.172
1.148
6.698
7.558
48.746Zn

1.942

74.500100

Pure CO290

CO2 + Cyanex 272

80

CO2 + Cyanex 272 + US

Extraction efficiency(%)

The chelation-SFE-ultrasound system consists of
two units, an SFE unit and an ultrasonic unit, which
are equipped on top of the extractor as shown in Fig.
2 and Fig. 3. The system consists of a CO2 cylinder,a syringe pump and its cooling unit, an SUS
extractor (130 mL), a power generator, anultrasonic transducer, and a separator. High purity
CO2 (>99:999%, Daesung Co. ROK) used as thesupercritical solvent was compressed to the desired
operating pressure by the syringe pump (model
260D, ISCO Inc., Lincoln, NE) with a controller(series D, ISCO Inc.). CO2 was then sent into thehigh pressure extractor containing 10g of soil
sample and 1 mL of Cyanex 272 as a chelating
agent. The extractor was heated to the desired
extraction temperature by a temperature controller.
In addition, the horn type ultrasonic processor (20kHz, Sonics & Materials, VCX 750) installed on
top of the extractor supplied a power of 316 W/cm2
with pulse on (3 sec) and off (3 sec) when operating
the system. The valves and tubes at the exit of theextractor were heated to 343 K to avoid
condensation by the heating coil. The extracted
metal species was captured by 60 mL of separator.

70
60
50
40
30
20
10
0

As Ba

Be Cd Co CrCu

Ni

Pb Sb Ag

Metal species

Se TI

V

Zn

Fig. 4 Comparison of extraction efficiency of metal
species from the soil samples using pure CO2, CO2 +Cyanex 272, and CO2 + Cyanex 272 + Ultrasound.

The series of experiments were conducted to establish
the influence of supercritical pure CO2, CO2 + Cyanex
272, and CO2 + Cyanex 272 + Ultrasound, for thesoil samples of pH 4.10. The experimental
conditions were fixed at 40℃, 16 MPa, 10 min
static and then 20 min dynamic extraction time, aflow rate of 3 mL/min CO2, and an ultrasound of 316
W/cm2 at 20 kHz with a duty ratio of 50 % and a
period of 6 s. In addition, the ultrasound wasapplied during the 10 min static time and thenduring the first 5 min of 20 dynamic extraction time.
As indicated in Fig. 4, the extraction efficiency ofmetal species showed in the ascending order of pure
CO2 < CO2 + Cyanex 272 < CO2 + Cyanex 272 +Ultrasound for most of the metals. The extraction of
metal ions by only supercritical CO2 was confirmed
to be inefficient because of the charge neutralization
requirement and the weak solute-solvent interaction.
Since the active component of Cynanex 272 is a
phosphinic acid, the metals (with the exception ofAs, Be, Sb, Ag, Se and Tl), were extracted througha cation exchange mechanism. Using ultrasoundwith a chelating agent (Cyanex 272) could substantiallyenhance the extraction efficiency, as suggested inprevious literature [5], by facilitating mass transport
which helps to move the solubilized metal or
metalloid species into the supercritical fluid phase.
A further study will be carried out for the importantparameters controlling chelation-SFE-ultrasoundsystem such as chelating agent type, water content,
pH, temperature, pressure, soil matrix and sonication
time.
References
1. C. Kersch, M.J.E. van Roosmalen, G.F. Woerlee and
G.J. Witkampc: Ind. Eng. Chem. Res. 39 (2000) 4670.
2. S. A. Fatah, M. Goto, A. Kodama and T. Hirose: J. of
Supercritical Fluids, 28 (2004) 21.
3. F. Chang, H. Kim, B. Joo, K. Park and H. Kim: J. of
Supercritical Fluids, 45 (2008) 43.
4. T.I. Trofimov, M.D. Samsonov, S.C. Lee, N.G. Smart andC.M. Wai: J.Chem Technol.Biotechnol 76 (2001) 1223.
5. C.M. Wai and Y. Enokida: U.S. Patent 7,128,840 B2(2006).

2P8-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 313- 314
11-13 November, 2008

Optimization of Ultrasound Irradiation for the Soil
Washing of Diesel-Contaminated Fine Particles
Beomguk Park‡, Jihoon Cha, Younggyu Son, Myunghee Lim and Jeehyeong Khim†(Dep. of Civil, Environ. and Architect. Eng. Korea Univ., Korea)

1. Introduction
The soil washing process is an innovative cleanup method used in soil remediation technologies. It
can effectively remove many types of pollutants
including petroleum hydrocarbons and heavy
metals and the treatment process can be finishedwithin a relatively short period.1)
The aim of conventional soil washing process isthe separation fine particles from bulk soil. Because
most pollutants in soil are concentrated on fineparticles and these fine particles commonly tend to
be attached to coarser particles. 1), 2)
Ultrasound, which is applied in many industrial
fields has recently been extensively investigated foruse in the soil washing process. The application ofultrasound causes acoustic cavitation that produces
a high speed microjet, a shock wave and a microstreaming due to the asymmetric collapse on thesurface of the soil. These can enhancetransportation rates. 3)
Previous studies on ultrasonic soil washingtypically focused on the parameters of ultrasound,soil and pollutants such as power intensity, initialconcentration, particle size etc.4),5) Most researchers
used particles that were larger than 0.1mm and that
had a high efficiency using conventional soil
washing processes and ultrasound. However, incomparison to coarse particles, fewer studies havebeen carried out on fine particles that arecontaminated with a high concentration ofpollutants. The purpose of this study is to estimate aremoval efficiency in soil washing processaccording to frequency, power and mixing forremoving diesel from contaminated fine particles
by using the ultrasound.
-------------------------------------------------------------hyeong@korea.ac.kr

2. Experimental Procedures
Experiments were carried out on the diesel
contaminated soils. Granite soil, which is very
common in Korea, was used after being air-driedand sieved. Particles which pass through a # 200
were used. Diesel fuel was purchased from a gas
station in Seoul, Korea. The diesel was dissolved inn-pentane.
The mixture was then added to the soil andmade homogenous. Initial concentrations of diesel
in the soil were 10,000mg/kg. An ultrasoundradiation experiment was then carried out after then-pentane in the soil was completely evaporated.
A bath type sonicator (Flexonic, Mirae
Ultrasonic Tech., Korea) with a frequency of 35,
170 kHz and 100, 200W power was used. A mixtureof 5mg contaminated soil and 15mL water wasadded into a 400mL cylindrical bath reactor toprevent compaction and was ultrasonically
irradiated for 10min while mixing at 100-200 rpm.
The reaction temperature was kept constant at
25±2℃ by a water cooling system.

Fig. 1. Scheme of ultrasonic bath and reactor

After sonication, the mixtures were placed intoa centrifuge in order to separate the solid and liquid
phases. A 5 g sample of soil was placed into abeaker and anhydrous sodium sulfate was added toremove moisture. The soil sample was thenextracted with 100mL of dichloromethane. The
diesel concentration was then measured for total
petroleum hydrocarbon (TPH) with a GC-FID(Agilent, 6890N, USA).
3. Result and Discussion

An investigation was carried out on the optimum
conditions of ultrasonic soil washing forremediation of fine particles contaminated withdiesel. The removal efficiency of sonication isshown in Fig. 2. The removal efficiency of diesel on
35 kHz is higher than 170 kHz in a low rotation
frequency (100W-100rpm, 200W-100rpm). In ahigh rotation frequency, the efficiency is almost thesame (100W-200rpm, 200W-200rpm). This isbecause the energy input at a high power andmixing is sufficient to achieve maximum removalusing ultrasound and mixing.
The rotational frequency effect is more efficientthan the power effect. However, a comparison ofquantitative physical energy is required.

Fig. 3. Cavitation energy according to frequency

The reaction temperature increased according tosonication time. Despite the same electronic energy
input, the cavitation energy differed from frequency.
Low frequency is a more effective way to transfer
energy from electronic energy to cavitation energy
than high frequency. Therefore, the removal rate ofdiesel is higher in low frequency than in highfrequency with the lower rotational frequency (100rpm).
Acknowledgments
This subject is supported by Ministry ofEnvironment, Republic of Korea as “The Ecotechnopia 21 project” (no. 061-081-042).
References

Fig. 2. Removal efficiency according to frequency,
power, and rotational frequency

Initially, in order to consider energy, wemeasured the increasing temperature according totime to compare the cavitation energy in less direct
ways. The results are shown Fig. 3.

1. T.J. Mason, A. Collings and A. Sumel : Ultrason.
Sonochem. 11 (2004) 205.
2. R.G.Sheets and B.A. Bergquist : J. Hazard.
Material. 66 (1999) 137.
3. A.F. Collings, A.D. Farmer, P.B. Gwan, A.P. Sosa
Pintos and C.J. Leo : Minerals Engineering 19(2006) 450.
4. S. Na, Y. Park, A. Hwang, Y. Kim and J. Khim :Jpn. J. Appl. Phys. 46 (2007) 4775.
5. D. Feng and C. Aldrich : Adv. Environ. Res. 4(2000) 103.
6. I. Hua and M.R. Hoffmann : Environ. Sci.
Technol. 31 (1997) 2237.

2P8-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 315- 316
11-13 November, 2008

Compaction of Soft Magnetic Composite Powderusing Ultrasonic Vibrations
超音波振動を用いた絶縁被膜鉄粒子の圧縮成形
Shinichi Kikuchi1‡, Daisuke Koyama1, Kentaro Nakamura1 and Hyun-Lok Cha2
(1 P & I Laboratory , Tokyo Inst. of Tech.; 2KITECH)
1‡
菊池慎一 ，小山大介１，中村健太郎１, Hyun-Loc Cha２（1東工大 精研; 2KITECH）

1. Introduction
To fabricate efficient electromagnetic motors
being based on the optimized design, a technique to
produce three-dimensionally-shaped magnetic coreis required. The metal powder compaction method
is a promising candidate for making arbitrary
shaped cores. However, it is difficult to increase thedensity and uniformity using conventional pressing
machine. This results in low magnetic efficiency
and low mechanical strength. To overcome thisproblem, we propose to introduce ultrasonicvibrations in the compacting process. We expect theincrease in the density of the compressed powder.
Also, we expect to reduce the friction between thedie and the work being based on the report whichshowed that high frequency vibrations have such
effects to lower the friction coefficient even though
the vibration amplitude is around 1-10 microns(1). In
this report the effects of ultrasonic vibrations on thecompaction rate are experimentally studied underhigher previous study.

Compaction system is shown in Fig. 1. SMC
powder set in the compacting part of the vibration
die’s center is compressed by a hydraulic pressing
machine. Methods of the application of theultrasonic vibration are(1)radial vibrations of the compaction die at 28
kHz,(2)longitudinal vibrations of the upper and lower
punches at 40 kHz, and(3)both (1) and (2) .
In this report, we focus on the 28-kHz radialvibration method and compression experimentusing it.
4. Radial vibration die
The fabricated vibration system and the vibration
mode are shown in Figs. 2 and 3. The die is madeof SKH-9 steel, and operated in the fundamental

BLT
Sample hole

2. Soft magnetic composite powder
Soft Magnetic Composite(SMC) powder is ironpowder which is covered with insulating film. We
used SMC550 with the particle size of 120 μm and
SMC500 with the particle size of 150 μm(2).
3. Compaction molding system
press

Vibration die

Fig. 2 the 28-kHz radial vibration system.

Hydraulic press
Upper punchmachine
BLT×8

Vibration die
Samplevibration

SupportLower punch

Fig.1 Compacting system.

-----------------------------------------------------------kikuchi.s.ac@m.titech.ac.jp

Fig. 3 Radial vibration mode by ANSYS.

Φ = 10 mm
D
T = 50 mm

Amplitude [μm]1

Fig.4 Vibrating compaction die.
3

Compacts Density [g/cm ]Freqency [kHz]h = 40 mm

28
h=0
121

0.4
0.2

h = 30 mm

122 123 124
Diameter D [mm]125h = 40 mm

100
200
Position [mm]300

Fig. 5 Vibration distribution in the radial direction.

29

27
120

0.6

0
0

h

h = 30 mm

0.8

126

Fig. 6 Relationship between the diameter of die andthe resonance frequency for the radial mode.

radial mode. It has a 10-mm-diameter compacting
part in the center and eight bolt-clamped Langevin
PZT transducers 30 mm in diameter. Using finite
element analysis, the shape of the die as shown in
Fig. 4 was determined, where a large vibration
amplitude can be obtained on the inner surface ofthe center hole at the frequency of 28 kHz. A
couple of examples with the numerical results areshown below. The vibration distributions in theradial direction for different joining areas are shownin Fig. 5. The resonance frequency of the vibration
die as a function of the width of joining area isshown in Fig. 6. From these results, we chose 30
mm for the width of joining area and 123 mm forthe diameter of the vibration die. Impedance
characteristics of the radial vibration die were
measured across the input of the transducer with
8-parallel connection the resonance frequency is28.12 kHz, the free motional admittance is 30 mS,
and the quality factor is 140.

5. Results of compression experiment
Relationship between the sample density and thevibration amplitude of the vibration die is shown in

6.6

6.4

6.2
● SMC 550
▲ SMC 500
60

0.5
Amplitude [μm]1Fig. 7 Density vs. the vibration amplitude of thecompaction die.

Fig. 7. The compacting static pressure is 300 MPa
constant. The compacting time is 8 sec. The density
increases with the vibration amplitude of thevibration die.
6. Discussion and Conclusion
We developed a 28-kHz ultrasonic radial vibration
die for powder compaction enhancement. The
apparent increase in the density due to theultrasonic vibration application has been confirmed
for a medium range static pressure in theexperiment using SMC. We shall design upper andlower vibration punch which are excited by a
40-kHz ultrasonic longitudinal vibration, and carryout compression experiment using it.
7. References
1. J. Tujino, Y. Atumi, T. Ueoka, J. Yamamoto and
K.Wakasaki: Proc. Spr. Meet. Acoust. Soc. Jpn.
pp. 617-618 (1982) (In Japanese).
2. http://www.hoganas.con/japan/

2P8-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 317- 318
11-13 November, 2008

Comparison of Magnetic Properties of SMC Motor
Core Fabricated by Ultrasonic Vibration Compaction
Hyun Rok Cha1†, Shinichi Kikuchi2, Seoung Kyu Jeon1, Sung Ho Lee1, Cheol Ho Yun2
and Kentaro Nakamura2 (1 Facult. Eng., KITECH.; 2Facult. Eng., Tokyo Tech.)

1. Introduction
Recently, Soft Magnetic Composite(SMC)
cores for reactor, transformers and various kind of
motor have drawn great attention among
researchers of magnetic and electric industry. The
SMC is ferro-magnetic powder particles surroundedby an electrical insulating layer. This charateristic
has advatage in a motor desing such as compact andlight-weight, because the magntic core has higher
degree of freedem in shape compare to the coremade out silicon steel. Also it has lower loss andsuperior magnetic properties than laminated siliconsteel at high frequency range since the insulation
coating of every particle gives very small eddy
current paths inside a particle. Generally it was
produced by cold compaction.[1] However, it isdifficult to remove the compresed core from the die
without break after compaction process since thepressure for the compaction process is extremly
high.[1,2] To overcome this problem, we propose to
introduce ultrasonic vibrations to the die to reduce
the friction.
In this paper, the SMC motor core wasfabricated by ultrasonic vibration compaction.
Magnetical properties and electrical propertis areinvestiged.

Upper Punch
Die
Vibrator (PZT)
FixturLower Punch
Load cellFig. 1 The arrangement of ultrasonic vibration press

Magnetcoil
Core
Housing

Fig. 2 The construction of the tested motor

2. Experimental Procedure3

Density[g/cm ]

6

5

0

0
0
4

2.Tokyo institute of tecnolgy : knakamur@sonic.pi.titech.ac.jp

SMC550KE With Vibration
SMC550KE Without Vibration
SMC550 With Vibration
SMC550 Without Vibration
SMC500 With Vibration
SMC500 Without Vibration

00
3

1.Korea Institute of inductiral technology : hrcha@kitch.re.kr

7

0
0
1

For this research, ultrasonic vibration press
was prepared. Fig.1. shows the arrangement of theultrasonic vibration press. It is consisted of an upperand lower punch, vibration compacting die designfor operating 20kHz half wavelength longitudinal
vibration and a press frame with a hydraulic staticcompacting pressure source. The vibration die
consists of vibration source with six bolt-clamped
Langevin type PZT transducers and support fixture.
The die is driven by 1kw high speed bipolar
amplifierTo review the possibility of SMC application
to general motors, it is adopted for high speed
motor. Fig 2 shows the construction of the tested
motor and shape of fabricated SMC core. The
powder specimens for SMC core are used Somaloy
550KE, 550, 500( Höganäs AB) respectively.
------------------------------------------------------------

MPA

Fig. 3 The compact density obtained by ultrasonicacting and conventional compaction

They are cold pressed from 100 to 400MPa using
proposed ultrasonic vibration press and thenheat-treated. The heat treatment temperature was
gradually increased with speed of 4℃/min up to
500℃ and then held for 1 hour in atmosphericcondition.
Motor performance analysis was carried out by
dynamometer (WB100). In order to analyze themagnetic property, Iron loss & Hysteresis
characteristic analyzer (MPG100D) was used.

1200

Iron loss[W/kg]

900

400

800

1200

1600

Frequency [Hz]Fig. 4 The iron-loss according to frequency with andwithout vibration action(a)(b)
Fig. 5 The appearance of a prototype motor andassembled SMC core (a): Motor Ass’y, (b): Core Ass’y

Output without vibration
Eff. without vibration
Output with vibration
Eff. with vibration

Torque without vibration
Current without vibration
Torque with vibration
Current with vibration

45
4
30

15
2
0

0.2
0.1
0.0
-0.1
-0.2

-15

-30
16000

18000

20000

22000

24000

Torque[kgcm] / Current[A]In this research, Ultrasonic vibration press wasintroduced to improve the magnetic prosperity. The
proposed method increased density about 2~5%,
improved magnetic properties and increased motor
efficiency more than 9%.

0

Output[w] / Efficiency[%]

4. Conclusions

600

300

3. Results and Discussion

Fig.3. shows the compact density obtained byultrasonic acting and conventional compaction of
SMC specimen under the pressure of 100, 300 and
400MPa respectively. As shown, the compact
density increased after ultrasonic acting. Especially,
the compact density of the ultrasonic compacted
SMC550 under the pressure 300MPa was 5.5g/㎤,
while that of conventionally compacted composite
was 5.2 g/㎤.
Fig.4. shows the iron-loss according to frequency
with and without vibration action. As shown, theiron-loss of SMC core is totally decreased byultrasonic action. The values of hysteresis loss are
more than eddy current loss in total iron-loss when
we increased the frequency. Generally, thehysteresis loss can be reduced by improving thestressed regions.[1] It means that the ultrasonicaction has a possibility to improve the stressedregions during compaction action.
The appearance of a prototype motor andassembled SMC core was shown in figure 5.
Fig.6. shows the results of dynamic motor
performance having SMC core both ultrasonictreated and no treated one. The results clearlyshows that the motor efficiency and torque isdramatically increased by using ultrasonic vibration
die. The ultrasonic treated SMC motor shows ahigher motor efficiency by more than 9% under the
rated speed of 24,000rpm.

Total lron loss without vibration
Total Iron loss with vibration
Hysterisis loss without vibration
Hysterisis loss with vibration
Eddy current loss without vibration
Eddy current loss with vibration

26000

Rotational Speed [RPM]

References
1. H. Shokrollahi and K. Janghorban : J. Mater.
Processing. Tech (2007).
2. Jiromaru Tsujino and Haruo Suzuki: Jpn. J. Appl.
Phys. 31 (1992) pp 290-293.

Fig. 6 The results of dynamic motor performance having
SMC core both ultrasonic treated and no treated one

2P8-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 319- 320
11-13 November, 2008

Room-Temperature Ultrasonic Bonding of Semiconductor Thin-Dies
with Die Attach Films on Glass Substrates
Siu Wing Or*, Sui Yin Wong, and Ho Chi Wong (The Hong Kong Polytechnic University)
Yiu Ming Cheung and Ping Kong Choy (ASM Assembly Automation Ltd.)
1. Introduction
The revolutionary reduction in thickness (<75μm) of semiconductor dies in the recent years has
imposed a significant limitation on conventional
conductive epoxy-based die bonding as a result of
the failures caused by epoxy overflow, coverage,
spread-out, and its induced die tilt. The
state-of-the-art thermocompressive bonding ofthin-dies in form of wafer-back laminates with die
attach films (DAFs) is not subject to such fluidic
problems at the expense of requiring a high bonding
temperature, a long bonding time, and a large
bonding pressure [1]. The process window of highbonding temperature and pressure, together with the
low throughput due to long bonding time, exerts agreat challenge to the advance of the thin-die
bonding technology. In this paper, a novel
ultrasonic thin-die bonding technique is proposed to
improve the process window and to increase thethroughput compared to the state-of-the-art
thermocompressive thin-die bonding technique. The
proposed technique is essentially based on theproper transmittal of ultrasonic vibration energy
generated from a piezoelectric ultrasonic transducer
to softening, plasticizing, and adhering the DAFs
between the associated thin-dies and theirsubstrates.

held by a vacuum-based, temperature-controlled
worktable, and a thin-die-DAF laminate is picked
and placed onto the glass substrate. Second, thespecimen is pressed by the transducer with apressure, and the ultrasonic energy is applied by thetransducer through the thin-die to softening andplasticizing the DAF so as to adhere the thin-die
and the glass substrate. Comparing to thestate-of-the art thermocompressive thin-die bonding,this ultrasonic thin-die bonding techniqueessentially requires much lower temperature andshorter time to be described in Section 3.

2. Setup and Working Principle
Fig. 1 shows the in-house automated equipment
model for the ultrasonic thin-die bonding. The
equipment model basically consists of a 40 kHz,
500 W piezoelectric ultrasonic transducer and its
ultrasonic signal generator, a vision system, athree-axis linear motion system, a pressure control
system, and a thermal management system. Fig. 2
illustrates the photograph and schematic diagram ofa standard test specimen used in the present study.
The test specimen has a thin-die of 8 mm long, 6
mm wide, and 50 μm thick laminated with a 10 μm
thick DAF and the thin-die-DAF laminate is to bebonded on an 1 mm thick glass substrate. The
reasons for selecting glass as the substrate are: (1) It
is transparent and the bond quality can be inspectedvisually immediate after each bonding; and (2) thischip-on-glass (COG) configuration represents oneof the most important configurations in modern
semiconductor packages.
In a bonding operation, the glass substrate is first-----------------------------------------------------------* E-mail: eeswor@polyu.edu.hk

Fig. 1. The in-house automated equipment model for theultrasonic thin-die bonding (top) and the zoom-in view of
the 40 kHz, 500 W piezoelectric ultrasonic transducer(bottom).

Fig. 2. Photograph (left) and schematic diagram (right) of astandard test specimen used in the present study.

3. Ultrasonic Bonding Studies
Based on the equipment model and the test
specimens, a series of experiments were performed
to investigate the effect of introducing ultrasonicvibration energy on the reduction of bonding
temperature, bonding time, and void formation in
the ultrasonic thin-die bonding process. The voids
formed along the bond interfaces were visuallyinspected using a digital optical microscopy
technique and the percentage of void formed wasrecorded. The ultrasonically bonded test specimens
were compared with the thermocompressively
bonded test specimens in terms of bonding
temperature, bonding time, and percentage of voids
formed.
Table 1 shows some typical results of the
proposed ultrasonic thin-die bonding and thestate-of-the-art thermocompressive thin-die bonding.
It is clear that the use of ultrasonic energy iscapable of establishing the quantitatively goodbondability with less than 10 % voids at a lower
bonding temperature of 80 ºC and a shorter bondingtime of 1.5 s (Specimen A) as compared with thethermocompressive bonding of 160 ºC bonding
temperature and 2 s bonding time (Specimen B). By
using the same bonding time of 2 s, it can evenrealize the technologically important and physicallyinteresting room-temperature thin-die bonding(Specimen C) with void formation less than 10 %.
Interestingly, the voids associated with thisroom-temperature ultrasonic bonding are >50 %reduced from the thermocompressive bonding at
120 ºC with 2 s (Specimen D).
4. Conclusion
We have developed a novel ultrasonic thin-die
bonding technique and its associated piezoelectric
ultrasonic transducer and prototype equipment
model to improve the process window and toincrease the throughput limited intrinsic in thestate-of-the-art thermocompressive thin-die bonding
technique. Room-temperature ultrasonic bonding ofthin-die-DAF laminates on glass substrates has
been successfully achieved using 2 s bonding timewith less than 10 % voids. To obtain comparable
results, it has been found that bonding temperaturein excess of 120 ºC is generally required in thethermocompressive process.
Acknowledgment
This work was supported by the Innovation andTechnology Fund of the Hong Kong Special
Administrative Region (HKSAR) Government
under Grant No. GHP/003/06.
Reference
1. A.C.C. Chong and Y.M. Cheung, “Post-bondCompression Process for Bonding Thin-Die on
BT Substrate using Thermoplastic Adhesive
Tape,” Proc High Density Microsystem Design
and Packaging and Component Failure Analysis,
2005 Conference, June 2005, pp. 1-6.

Table 1: Comparison of ultrasonic and thermocompressive thin-die bonding results for the test specimens.
Specimen

Bonding Technique

Bonding
Temperature(ºC)

Bonding
Time(s)

Percentage ofVoid Formed(%)

A

Ultrasonic Bonding

80

1.5

5

B

Thermocompressive
Bonding

160

2

5

C

Ultrasonic Bonding

Room
Temperature

2

9

D

Thermocompressive
Bonding

120

2

20

OpticalMicrograph2P8-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 321- 322
11-13 November, 2008

Design of Ultrasonic Horn for Microelectronic Parts– Material Dependence
Minseok Bae‡, Young H. Kim (Korea Science Academy)
Jeong-Hoon Moon (Dept. of Mechanical Eng., Suwon Science College)
Kyung-soo Kim (Changjo Engineering Co.)
1. Introduction
High-density packaging technologies arecontinuously developed for high-performancemicroelectronic parts. For example, micro-pitch
terminals or flip chips without a plastic package are
employed for the miniature electronic devices.
However, it is hard to bond those small and highdensity devices with traditional soldering process.
In addition, lead-free bonding technology isrequired for environment. To address those
problems, ultrasonic bonding technique has beendeveloped [1].
It is essential to analyze vibration modes andresonance frequency of ultrasonic horn to obtain
good bonding quality. FEA (Finite Element
Analysis), that can be used various scientific andengineering fields to simulate complex situation,
can be also used to analysis ultrasonic horn [2].
Vibration modes and eigen frequencies of theultrasonic horns are dependent on horn materials.
Hence, choosing the best horn material is needed toobtain high-quality ultrasonic bonding.
In this research, ultrasonic bonding horns withvarious horn materials are designed using FEA.
COMSOL 3.4 is used for analyzing eigen modes
and frequency response of each horn [3].
2. Design Criteria
Fig. 1 shows a schematic diagram for ultrasonicbonding of IC chip on a substrate. Transverse
vibration is needed to bond IC chip on a substrate.
To cause transverse vibration of IC chip, ultrasonichorn should have longitudinal motion. If ultrasonichorn vibrates other direction, IC chip can bedamaged or bonding will not be succeeded.
Therefore, longitudinal modes were considered for
an appropriate bonding. Resonant frequency of thelongitudinal mode was tuned near 40 kHz.
Typical vibration modes near the longitudinalmode of a 59×28×14mm3 rectangular block wereobtained. Fig. 2 shows the desired vibration modeand two nearest modes of the block. The
longitudinal mode should be separated from othernearest modes, or proper bonding quality cannot be
obtained [4].

bms1991@empal.com

Fig. 1 Schematic diagram of IC chip bonding.

(Nearest mode) (Desired mode) (Nearest mode)
Fig. 2 Vibration modes of a rectangular block.

3. Properties of Horn Materials
Vibration modes and resonant frequencies are
determined by horn materials and horn dimensions.
Therefore, horn dimensions should be changed for
different horn materials. In the present work, threehorn materials are used for ultrasonic horn design.
The mechanical properties of those materials were
measured before FEA. Speeds of longitudinal andtransverse waves were measured using pulse-echo
setup, and densities were by Archimedes principle.
The measured mechanical properties of three horn
materials are listed in Table 1.
Table 1 Mechanical properties of horn materials.
Density Elastic Moduli (GPa) Poisson’s
Materials
Ratio(g/cm3) Young’s
Shear
JPN
7.688
196
74.6
0.312
SKD11
7.708
217
84.5
0.280
SKH
8.110
234
91.4
0.285

4. FEA of ultrasonic horns
It has four steps to design ultrasonic horns: (1)Basic horn structure, (2) Add 2 fixtures & grip
fixtures, (3) Add welding tip, and (4) Add suction
hole.
After final step, vibration modes were separated
about 3 kHz. The vibration mode and dimensions of
final model are shown in Fig. 3 and Table 2.
Resonant frequencies of final models are in Table 3.
Three horn materials showed well-separated

in Table 4. Measured one showed good agreementswith simulated one.

resonant frequencies.

Table 4 Resonant frequencies of manufactured horns.
Resonant frequencies (kHz)Horn Materials
Simulated
Measured
JPN
39.75
40.90
SKD11
39.96
39.80
SKH
39.84
40.07

(a)

(b)
Fig. 3 Desired mode & dimensions of final welding horn.
Table 2 Length of x for four horn materials.
Horn materials
JPN
SKD11
X (mm)
59
62

Ultrasonic bonding results are shown in Fig. 5
and Fig. 6. Chip size was 6×10mm2 and gold bumpsize was 100×100um2. Silicone base with gold
coating was used. Flatness of horn and chip was notproper, so some portions were only bonded.
However, bonding quality can be improved withmore accurate alignment in mechanical system.

SKH
63

Table 3 Resonant frequencies of final designed horns.
Resonant frequencies (kHz)HornMaterials
BeforeDesiredBehind
JPN
36.88
39.75
42.53
SKD11
36.99
39.96
43.46
SKH
36.81
39.84
43.53

Fig. 5 US bonding results-chip and base-JPN horn.

5. Frequency response analysis of the horn
Frequency response analysis for 30.0 kHz to 50.0
kHz frequency range of JPN horn was also obtainedby FEA (Fig. 4). The maximum x-direction
displacement appears at about 39 kHz and it
showed good agreement with resonance frequency.
Calculated Q factor is about 4.88. This result shows
it can be nicely used to obtain proper transverse
motion of a chip.

Fig. 6 US bonding results-chip and base-SKH horn.

Fig. 4 Frequency response result of JPN horn.

6. Evaluation of manufactured ultrasonic horns
Ultrasonic horns designed by FEA were
fabricated. Different horn materials cause different
size of the horns. Simulated resonance frequencies
and measured resonant frequencies were compared

7. Conclusion
Ultrasonic welding horn using various horn
materials has been designed by FEA with material
constants measured by experiment. Two projections
on both side of horn and two fixtures on the node ofhorn separated resonant frequencies of neighborvibration modes. Designed ultrasonic horns were
fabricated. As results, resonant frequency offabricated horn showed good agreement withdesigned frequency. Primary bonding test withfabricated horn shows feasible results.
References
1. J. Tsujino, Y. Harada, S. Ihara, K. Kasahara, M.
Shimizu, T. Ueoka: Ultrasonics, 42 (2004) 125.
2. L. Parrini, Ultrasonics, 41 (2003) 261.
3. COMSOL AB, COMSOL version 3.4 (2007)
4. J.A. Gallego-Juarez, E. Riera, V. M. AcostaAparicio: Nonlinear Acoustics- Fundamentals andApplications (ISNA 18), 18th International
Symposium

2P9-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 323- 324
11-13 November, 2008

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2P9-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 325- 326
11-13 November, 2008

Sound Pressure Field Focused by Aplanatic Acoustic
Lens for Ambient Noise Imaging
周囲雑音イメージングのためのアプラナート音響レンズの集
束音場
Kazuyoshi Mori1† , Hanako Ogasawara1, Toshiaki Nakamura1, Yuji Sato2, Takenobu
Tsuchiya3 and Nobuyuki Endoh3 (1National Defense Academy; 2Univ. Tsukuba;
3
Kanagawa Univ.)†

森 和義1 ，小笠原英子1，中村敏明1，佐藤裕治2，土屋健伸3，遠藤信行3 （1防衛大学校; 2筑波大;
神奈川大）

3

1. Introduction

2. Design of Aplanatic Lens for ANI system

Buckingham et al. developed a new method
which views ambient noise as a sound source rather
than a hindrance and which is neither passive nor
active sonar. This method is called ambient noise
imaging (ANI).1 Some systems have been built for
ANI. In the first generation, the Acoustic Daylight
Ocean Noise Imaging System (ADONIS),
consisting of a 3 m diameter spherical reflector andhaving an array of 126 hydrophones attached to the
focal surface, was built by Epifanio andBuckingham et al.2 In the second generation, theRemotely Operated Mobile Ambient Noise Imaging
System (ROMANIS), consisting of a 2-D sparsearray of 504 hydrophones fully populating a 1.44 m
circular aperture, was built by Venugopalan et al.
Both systems successfully detected silent target
objects using snapping shrimp noises.3
On the other hand, an acoustic lens system
would be a powerful choice for realizing ANI,
because such a system would not require a large
receiver array and a complex signal processing unit
for two-dimensional beam forming, which could
reduce the size and cost of the system. In our paststudies, we analyzed a sound pressure field focusedby an acoustic lens system constructed for an ANI
system with a single spherical biconcave lens using
the 2-D and 3-D Finite Difference Time Domain(FDTD) method and the small scale trial in watertank. Our aim was the development of a lens with aresolution similar to the beam width of ROMANIS,
which is 1 deg at the frequency of 60 kHz. These
results showed that the lens with a aperture
diameter of 2.0 m has the sufficient resolution.4, 5
In this study, an aplanatic lens correcting theaberrations is applied to ANI system. We analyized
the sound pressure distribution focused by the
acoustic aplanatic lens using the 3-D FDTD method.
We then compared the analysis results of –3 dB
areas with those of the spherical lens.

An absolutely aplanatic lens must satisfy thefollowing three conditions. First, both surfaces oflens are aspherical. Secondly, the lens must satisfy“the principle of equal optical path” in order toconcentrate rays of normal incidence completely.
The principle of equal optical path means that the
optical paths of all rays are equal when they
originate at the same source, even if they refract at
any surface. In the present case, this includes any
optical paths equal to the central optical pathbecause all rays are focused at the same point.
Thirdly, “Abbe’s sine-condition” must be satisfied
for all points of incidence. A coma aberration isremoved in a paraxial area when Abbe’s
sine-condition is satisfied without a sphericalaberration.
Yoshida6 developed a numerical method fordesigning aplanatic lenses which satisfy the above
three conditions in the case of optical convex lenses.
Sato et al. applied this method to the design of an
acoustic aplanatic lens. They evaluated theconvergence characteristics of the biconcave andbiconvex aplanatic acoustic lenses analyzed using
the ray path and the sound pressure distribution
obtained by the 2-D FDTD method.7. In a designing
process for ANI system, the authors comparedsound pressure fields focused by some asphericallenses including an aplanatic lens using the 2-D
FDTD method.8
In this study, the aplanatic lens was designed
as the following conditions; the aperture diameter is
2.0 m, the focal length is 2.5 m, and the center
thickness is 0.05 m. The lens shape and the raypaths are shown in Fig. 1. The rays concentrate oneach different point at the incidence angles of 0 deg
and 7 deg. In these cases, both spherical and comma
aberrations are corrected. However, the rays do notconcentrate on a point because this lens has a smallcomma aberration at 15 deg.

†kmori@nda.ac.jp

3. Results and Conclusion

The sound pressure distribution focused by
the aplanatic lens was calculated using the 3-D
FDTD method. The beam pattern is compared withthat of the spherical lens in Fig. 2. In the case of theaplanatic lens, the width of main-lobe is slightly
narrow and the peak level is large as compared withthe spherical lens. The side-lobe level of theaplanatic lens is smaller than that of the sphericallens. The –3 dB area, whose pressure is 3 dB lower
than the maximum at the image point, is used forevaluating the directional resolution of the lens, thesame as the 3 dB beam width. The –3 dB areas areshown in Fig. 3. Each –3 dB area of aplanatic lensis smaller than that of spherical lens. These results
suggest that the aplanatic lens has fine resolution ascompared with the spherical lens by correcting thespherical and comma aberrations. We have a plan tomeasure the sound pressure field focused by anaplanatic lens on a small scale trial in water tank.
The experimental results using the lens of 1/5 scale
will be compared with these analysis results.

θ = 0, 1, 2, 3, 4 deg(a) spherical lens

-1.25
-1.00
-0.75

θ = 0, 1, 2, 3, 4 deg

radial distance (m)

-0.50
-0.25

0 deg

0.00

(b) aplanatic lensFig. 3 Comparison of –3 dB areas. (horizontal:
radial distance, vertical: axial distance, θ :incidence angle)

7 deg

0.25
0.50

15 deg

0.75
1.00
1.25
-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

axial distance (m)Fig. 1

Lens shape and ray diagrams.

0

aplanatic
spherical-5

relative pressure (dB)

-10
-15
-20
-25
-30
-35
-40
-45

-0.1

-0.05

0

0.05

0.1

radial distance (m)Fig. 2

Beam patterns of normal incidence.

0.15

References
1. M. J. Buckingham, B. V. Verkhout and S. A. L.
Glegg: Nature, 356 (1992) 327.
2. C. L. Epifanio, J. R. Potter, G. B. Deane, M. L.
Readhead and M. J. Buckingham: J. Acoust.
Soc. Am., 106 (1999) 3211.
3. P. Venugopalan, M. A. Chitre, E. T. Tan, J.
Potter, K. T. Beng, S. B. Ruiz and S. P. Tan:
Proc. Oceans 2003 Marine Technology andOcean Science Conf. (2003) CD-ROM.
4. K. Mori, A. Miyazaki, H. Ogasawara, T.
Yokoyama and T. Nakamura: Jpn. J. Appl. Phys.,
45 (2006) 4834.
5. K. Mori, H. Ogasawara, and T. Nakamura: Jpn.
J. Appl. Phys., 47 (2008) 4344.
6. S. Yoshida: Tohoku-daigaku Kagaku-keisoku
Kennkyuu-syo Houkoku, 6(3) (1958) 123. [inJapanese]
7. Y. Sato, A. Miyazaki, K. Mori, and T.
Nakamura: Jpn. J. Appl. Phys., 46 (2007) 4982.
8. K. Mori, H. Ogasawara, and T. Nakamura: to be
published in Acoustical Imaging, 29 (2008).

2P9-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 327- 328
11-13 November, 2008

FEM Analysis of low frequency and wideband array composedof disk bender transducers having differential connections
差動接続を用いた屈曲円板型低周波送波器アレイの広帯域化に関する FEM 解析
Mitsuru Yamamoto†, Takeshi Inoue, Hiroshi Shiba and Yuta Kitamura (NECCorporation)
山本満†，井上嵩梓，芝博史，北村佑太（NEC）

1. Introduction
In recent years, it has become necessary totransmit in low frequency and wideband frequency
for underwater sonar systems of oceanic
development and investigation. To address this need,
we had developed a disk bender transducer withdual radiation surface which utilized two
piezoelectric ceramic disks operating in an
unstiffened mode as high-power, miniature, lightweight and low-frequency transducer. However thisdisk bender transducer had the defect that thefrequency bandwidth was narrow because theradiation surfaces were small and the acoustic load
was small. Its fractional bandwidth became 10-20%
at most. Then, we studied the technology that madeit to wideband by two or more differential
connections of the disk bender transducers by using
finite element method (FEM) analysis. The wider
fractional bandwidth more than 100% was foundbeing able to be achieved from the result of theanalysis for differential connections of the three
disk bender transducers operating in different
resonance frequencies each other.

Piezoelectric ceramic (PZT)

Metal plate (Al)Elastic plate

Polarized direction

Fig. 1 Plane view and cross-sectional view of a disk
bender transducer.
zr

PZT piezoelectric material
Aluminum
PZT piezoelectric material

Acoustic element

2. Construction of disk bender transducer
The plane and cross-sectional views of thedisk bender transducer are shown in Fig. 1. The
transducer has two bender vibration disks. Eachvibration disk consists of a metal plate and apiezoelectric ceramic disk polarized in the thickness
direction. Each piezoelectric ceramic disk is firmly
bonded to the metal disk with an epoxy resin
adhesive, in a circular depression of the metal disk.
The two vibration disks are connected by an elastic
plate and clamped together with eight bolt-nut
assemblies with elastic springs. In actual operation,
when a voltage is applied to two piezoelectric
ceramic disks, they vibrate in phase in the radial
direction, which results in bending vibrations ineach vibration disks.

Fig. 2 Transducer simplified model for FEM
analysis.

------------------------------------------------------------

Fig. 3 Chart of connecting wires of low frequency
and wideband array composed of disk bendertransducers having differential connections.

E-mail: m-yamamoto@dq.jp.nec.com

Piezoelectric ceramic (PZT)
Metal plate (Al)Elastic plate

1st frequency transducer

2nd frequency transducer

Polarized direction

3rd frequency transducer

FEM analysis model of the transducer isshown in Fig. 2. For the purposes of simplifying theanalysis, we used transducer z-axis symmetricmodel and simple support model ignored eightbolt-nut assemblies and the elastic plate. It is no
problem in a relative evaluation of transmitted
voltage response (TVR) though the resonancefrequency is different in the analytical result of sucha model.
Figures 3 and 4 show the chart ofconnecting wires and concentrated constantequivalent circuit for the disk bender transducer
array having differential connections, respectively.
In Fig. 3, the polarized direction of the piezoelectric
ceramic for the 2nd frequency transducer is opposite
in them for another transducers. In Fig. 4, thisshows the equivalent circuit model with thetransformer turn ratio of -1:1. Because thetransformer works effectively, the array composedof the three disk bender transducers shown in Fig. 4functions as the multiple mode filters, and canobtain the bandwidth which is more than threetimes than that of an individual transducer. In theequivalent circuit in Fig. 4, mutual impedance wasdisregarded for the simplification.

The possibility that the wideband characteristic of100% or more is obtained was shown by adifferential connection of three disk bendertransducer array.
L
R
C
1

1

ZL1
L2

R2

C2

-1 : 1
ZL2

Cd2
L3

R3

C3

Cd3

ZL3

Fig. 4 Concentrated constant equivalent circuit forthe disk bender transducers array having differential
connections.
10
0
-10
-20
D=0.25λD=0.22λD=0.20λD=0.18λD=0.16λD=0.14λ

-30
-40
-50

4. Analysis results

0.0

1.0
2.0
3.0
Normalized frequency f/f0

4.0

Fig. 5 Theoretical transmitted voltage response by
FEM analysis when changing the diameter of the disk
bender transducer.
Transmitted voltage response [dB]

Figure 5 shows the calculated results of TVR
when changing the diameter of the disk bendertransducer. The thicknesses of those transducers
were assumed to be constant in 0.042λ, and thediameter of a piezoelectric ceramic was defined as
65% for the whole diameters of the transducers.
The peak values of the TVR do not change so muchthough the resonance frequency decreases as thediameter grows. Moreover, it is understood that Q
value becomes a rising narrowband while making to
the low frequency.
Figure 6 shows TVR for the array composedof the three transducers having differential
connections. In figure, plots are shown in TVR ofeach transducer and line is shown in TVR when thevoltage of out-of-phase was applied in the 2nd
frequency transducer. The peak values at threeresonance frequencies are almost the same and it isobtained -6dB fractional bandwidth of 100%.

1

Cd1

Transmitted voltage response [dB]

3. Analysis model

10
0
-10
-20
-30

D=0.14λ,D_PZT/D_Al=0.8
D=0.16λ,D_PZT/D_Al=0.7
D=0.20λ,D_PZT/D_Al=0.65
3elem. out-of-phase

-40
-50
0.0

1.0

2.0

3.0

4.0

Nomalized frequency f/f0

5. Conclusion

Fig. 6 Transmitted voltage response for the transducers
array having differential connections calculated by
FEM analysis.

The underwater performance of low
frequency and wideband array composed of disk
bender transducers having differential connections
were calculated by FEM. These analytical results
demonstrated that this transducer array has a
low-frequency and wide-bandwidth performance.

References
1. M. Yamamoto, Y. Hama, H. Shiba, N. Watari and
T. Inoue: J. Acoust. Soc. Jpn. 15, 5(1994) 311.
2. M. Yamamoto, H. Ishimura, Y. Hama and T.
Inoue: Jpn. J. Appl. Phys. 37 (1998) 3161.

2P9-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 329- 330
11-13 November, 2008

Optimal Design of a Barrel Stave Flextensional
Transducer
Hoeyong Kim and Yongrae Roh†(Kyungpook National University, Korea)

1. Introduction
Flextensional transducer can be classified
into 7 classes according to its operation principle,
and class I is known to have the most stablestructure for deep underwater applications due to its
concave shell [1]. The concave class I transducer isoften called barrel stave transducer. Many
researches have been done on the design of thetransducer structure. Systematic investigation,
however, has been quite rare [2]. Therefore, in thisstudy, we analyzed and designed the barrel stave
flextensional transducer to achieve the widest
frequency bandwidth by considering all the
cross-coupled effects of structural variables.
2. Modeling of a barrel stave flextensionaltransducer
The structure of a class Ⅳ flextensionaltransducer is described in Fig. 1 that shows a finite
element model constructed with the ANSYS®.
Harmonic and transient analyses were performed
with the model. Main structural components are apiezoceramic stack in the middle of the transducer,
a metallic flange to support the whole structure anda flexible concave shell surrounding the whole
structure. Dimensions and geometric shape of theseare of significant influence on the transducer
performance as evidenced in previous reports onother types of flextensional transducers. Hence, thiswork focuses on the analysis of the effects of thesevariables and the determination of the optimal
combination of these variables to have the widest
frequency bandwidth. Properties of the materials
composing the transducer are listed in Table 1.

Table 1 Material properties of each part of the transducer
Density(kg/m3)Young’s
Modulus (Pa)Poisson’s
ratio

Insert,FlangeInsulator

2,710

68.9E9

0.30

2,900

80.0E9

0.25

Shell

1,900

27.4E90.25

RubberCeramic
stack

1,100

3.0E7

0.49

PZT-4

3. Analysis of the transducer performance
In order to compare the transducer
performance for different combinations of thestructural variables, a basic transducer model wasconstructed to have the dimensions in Table 2. The
basic model was established to let the transducer
operate at 7.5 kHz and have a typical geometry inuse. Variation ranges of major design variables werealso established as in Table 3 considering practicalapplicability of the transducer. Over the range, theresponse of the transducer was investigated throughharmonic analyses with the model in Fig. 1. Resultsof the calculation were analyzed to find therelationship between the variables and thefollowing performance factors: bandwidth (Δf),
center frequency (fc), and transmitting voltage
response (TVR). Fig. 2 is an illustrative result thatshows the change of the Δf in relation to the shell
thickness. Fig. 2 shows that the bandwidth can be
maximized at a specific shell thickness. Similar
relationships were derived for all the othervariables.
Table 2

Basic geometry of the transducer
Shell thickness (x1)Fig. 1Finite element model of the transducer-----------------------------------------------------------†yryong@knu.ac.kr

7 mmFlange thickness (x2)24 mm

Flange length (x3)37 mm

PZT length (x4)

139 mmROC (radius of curvature) (x5)

410 mmRubber thickness

2 mm

PZT Thickness

10 mm

Inside diameter of PZT

5 mm

Table 3 Variation range of the structural variables of
the transducer
Structural variables

Variation range(mm)Shell thickness

5~9Flange thickness

18 ~ 30

Flange length

31 ~ 43

PZT length

118 ~ 160

ROC (radius of curvature)

320 ~ 500

Table 4

6200

Result of the optimization
variable

Optimized Value

x1 (mm)6x2 (mm)

29.94

x3 (mm)43

x4 (mm)118

x5 (mm)320

Basic model
Opimized model

1.08
1.04

6000

1.00
0.96

TVR [x T0 dB]

Bandwidth[Hz]

5800

5600

0.92
0.88
0.84
0.80

5400
0.76
0.72

5200

0.68
0.00

0.27

5000

0.54

0.81

1.08

1.35

1.62

1.89

2.16

Frequency [x f Hz]
5

6

7

8

9

shell thickness [mm]Fig. 2 Variation of performance in relation to shell
thickness.

Fig. 3models

TVR spectrum of the basic and optimized

Based on the results, fc, TVR, and Δf of thetransducer were derived as functional forms.
Formulation of the performance was carried out bymeans a second order multiple regression modeland a commercial software SAS® [3]. The goal ofpresent work is to design a transducer structure tohave the widest possible bandwidth whilesatisfying given constraints simultaneously. Hence,the combination of the structural variables was
optimized to minimize the target function in Eq. (1)while satisfying the two constraints in Eq. (2).

4. Conclusions

Target function: Minimize T = 1(1)

Constraint: fc - 100 Hz ≤ fc ≤ fc + 100 Hz
TVRpeak ≥ T0 dB

Acknowledgment
This work was supported by Defense
Acquisition Program Administration and Agency
for Defense Development in Korea.

(2)

Δf

For the minimization of the target function,
SQP-PD (Sequential Quad-ratic Programming
Method of Phenichny and Danilin) method wasused because of its high convergence rate [4].
Table 4 shows the results of the optimization. Fig.
3 is the corresponding performance of the
optimized transducer. Compared with the initial
basic model, the optimized structure shows a wider
bandwidth while its center frequency and TVRlevel meet given specifications.

The structure of a barrel stave flextensionaltransducer was designed to achieve the widest
bandwidth while satisfying other constraints
simultaneously. In comparison with conventional
analytic and finite element methods, the design
method in this paper can consider all the
cross-coupled effects of design variables and candetermine the detailed geometry of the transducer
with great efficiency and rapidity.

References
1. S. C. Butler, J. L. Butler, A. L. Butler, and G. H.
Cavanagh: J. Acoust. Soc. Am. 102 (1997) 308.
2. K. J. Kang and Y. R. Roh: J. Acoust. Soc. Am.
114 (2003) 1454.
3. R. E. McKeighen: IEEE Trans. UFFC 43(1996)
63.
4. D. A. Pierre, Optimization theory withapplications (Dover Publications, New York,1986).

2P9-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 331- 332
11-13 November, 2008

Analysis of the effect of reflected wave from sonar-domeon radiation impedance for cylindrical array
Jungsoon Kim1‡, Moojoon Kim2, Kanglyeol Ha2, Heeseon Seo3 and Cheeyoung Joh3
(1Dept. of Multimedia Eng., Tongmyong Univ.; 2Dept. of Physics, Pukyong Univ.;
3
6th R&D Institute, Agency for Defense Development)

1. Introduction
In designing underwater sonar system, suchas Hull-Mounted Sonar, the radiation impedance isvery important design factor because it is associatedto the radiation power of the system and the mutualinterference force among the vibrating elements[1].
In a practical system, the sonar has a dome toprotect the arrayed elements from the underwater
environment such as flow resistance and shockpressure. However, the acoustic wave from theelements is reflected on the surface of the dome,
and its effect on the radiation impedance cannot beignored [2].
In this study, to analyze the effect of thereflected wave on the radiation impedance, we
introduced a model which two vibrating elements
are mounted on an infinite planar rigid baffle and aplane reflector exists in front of the baffle. Using
this model, the variation of the radiation impedancewith the distance between the elements, theseparation from the reflector, the driving frequency,
and the complex reflection coefficient of thereflector are calculated. In the calculation, the Ring
function is introduced to evaluate the acousticpressure distribution by the reflector[3].
2. Theory
If a transducer array is consisted of N
elements on the rigid baffle, the total radiation
impedance of the n-th element is expressed asfollows[2];NuZn =Z mn m ,
(1)
un
m =1
where, u m and u n are vibrating velocity of the mth and n-th element, respectively. Z mn is the mutual
radiation impedance between the two elements. The
total radiation impedance with a reflector in front of
the array is represented by following equation.
N
um
'
,
(2)
Zn =
Z mn + Z mn
unm =1
where,
1
'
'
Z mn
=
p mn
dS m .
um S

∑

∑(

)

∫

n

-----------------------------------------------------------kimmj@pknu.ac.kr

S n is the vibrating area of the n-th element, dS m'
is the minute area of the m-th element. p mn
is thereflected sound pressure from the reflector.

Plane reflector with complex
reflection coefficient Γ

Rigid baffle

Image sourceof m-th elementp’mm-th elementn-th element

Fig. 1. Calculation model.
We assume that a plane reflector which has acomplex reflection coefficient Γ is placed in frontof the two piston sources mounted on an infinite
planar baffle, as shown in Fig 1. The sound pressureradiated by m-th element is reflected from thereflector, that is to generate the virtual image of them-th element on the reflector. The sound pressure
from the virtual image can be given by,exp(− jkl ) '
jρck
'
=
p mn
umΓ
dS m .
(3)
2π
l
'
S

∫

m

Here, ρ is the density, c is the sound velocity andk is the wave number of the medium. l is the
distance between dS m' in the virtual image of the mth element and dS n in the n-th element. Therefore,
the radiation impedance between the two elements
can be represented by,exp(− jkl ) '
jρck
'
=
Γ
Z mn
dS m dS n .
(4)
2π S ' S '
l

∫∫
n

m

For example, we assumed that the two
identical circular piston sources with the radius a
are mounted with the separation d on the baffle andthe reflector is separated from the baffle by z. Using
the Ring function[3], the mutual radiation
impedance is given as follows;
xF

rF

xN

rN

'
Z mn
= j 2πρckΓ xR2 (x ) R1 (r , x )exp(− jkr )drdx (5)∫∫(a + x )2 + z 2 , x F = b + d ,1.2

If 0 ≤ x ≤ a and z ≤ r ≤ (a − x ) + z 2 , R1 ( r , x) = 1
andwhen
0 ≤ d ≤ b and 0 ≤ x ≤ b − dthen
R2 (r , x) = 1 .

0.4
0.2
0.0

1.0

0.6
2

0.4
0.2
0.0

0.0
-0.2
-0.4
-0.6

1.0

1.5

2.0

2.5

3.0

3.5

0.5

1.0

1.5

z/λ

0.6

2.5

3.0

3.5

Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

0.8
0.6

2

0.4

X'mn/ρcπa21.0

Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

0.8

R'mn/ρcπa

2.0

z/λ

1.0

0.2
0.0
-0.2

0.2
0.0

-0.4

-0.6

-0.6
0.5

1.0

1.5

2.0

z/λ

2.5

3.0

3.5

1.5

2.0

2.5

3.0

3.5

d/λ

Fig. 3. The total radiation impedance considering
the reflected wave with d for various Γ.
ka = 1.54 and z = 1.2λ . In these results, thedifference between the resistance and the reactanceof the total radiation impedance increases withreflection coefficient Γ.
1.4

without dome
Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

1.2
1.0

Rtot/ρcπa

2

0.8
0.6
0.4
0.2

Xtot/ρcπa

2

0.0
0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

ka

The total radiation impedance variation with ka forvarious Γ shows in Fig. 4. The difference between
the result of with and without dome increases
according to Γ and ka in the given range.
Acknowledgment
This work was supported by Agency for
Defense Development of Korea, 2007.

0.4

-0.2

-0.4

1.0

0.2

-0.4

0.5

0.5

0.4

-0.2

-0.6

0.0

2

Fig. 4. The total radiation impedance variation withka.

Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

0.8X'mm/ρcπa2

0.6R'mm/ρcπa1.0

Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

0.8

Xtot/ρcπa-0.2

2

To investigate the variation of the radiation
impedance by the reflected wave from the sonardome, the radiation impedance for various z, d, ka
and Γ are calculated by using Eq. (2) and Eq. (5).
When ka = 1.54 , the variation of theradiation impedance for various z and Γ is shownin Fig. 2. In this figure, the x-axis is normalized by''
and X mmthe wavelength λ . When d = 0 , Rmm
mean the real part and the imaginary part of theself-radiation impedance, respectively, considering
the effect of the reflected wave from the reflector.
''
and X mnmean the realAnd, when d ≠ 0 , Rmnpart and the imaginary part of the mutual-radiation
impedance, respectively, considering the same
effect.

without dome
Γ = 0.0735-0.1882jΓ = 0.3661-0.4094j
Γ = 0.5498-0.4884j
Γ = 0.7725-0.4132j
Γ = 0.9086-0.2484j

0.6

Ztot/ρcπa

Calculation Results

2

0.8

2

3.

Rtot/ρcπa

1.0

2⎧⎪ (a − x )2 + z 2 , x > a⎧b − d , d > b, rN = ⎨rN = ⎨⎪⎩ z , 0 ≤ x ≤ a⎩0, 0 ≤ d ≤ b⎛ x2 − a2 − z 2 + r 2 ⎞1⎟,
R1 ( x ) = cos −1 ⎜
⎜
⎟
2
2
π
x
r
z
−
2
⎝
⎠
2
2
2
⎛ x + d −b ⎞1⎟.
R2 (x ) = cos −1 ⎜⎜
⎟
π
2
xd
⎝
⎠

Ztot/ρcπahere, rF =

0.5

1.0

1.5

2.0

2.5

3.0

3.5

z/λ

Fig. 2. The variation of the self- and mutualradiation impedance considering the reflected wave
from the reflector at z for various Γ .
The amplitude of variation of the self-radiation
impedance gradually decreased according to z.
However, the variation of the self- and mutualradiation impedance is dramatically changed as Γ
increased.
Figure 3 shows the change of the total
radiation impedance with d for various Γ in case ofReferences
1. T. Yokoyama, T. Asami, K. Mori, T. Nakamura
and A. Hasegawa: Jpn. J. Appl. Phys. 43 (2004)
3154.
2. Takashi Ikeda and Tetsuo Miyama: The Journalof the Acoustical Society of Japan, 33(1977) 342.
3. Shigeo Ohtsuki: The Journal of the AcousticalSociety of Japan, 30(1974) 76.
4. Lawrence E. Kinsler, Austin R. Frey Alan B.
Coppens James V. Sanders: Fundamentals of
acoustics ( John Wiley & Sons, 1980) p.124.

2P10-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 333- 334
11-13 November, 2008

Numerical simulation of sound field in time domainusing a combination of FDTD method and boundary
integral equation method
FDTD !"%

Takao Tsuchiya and Atsushi Kumagai (Doshisha Univ.)†
$&# ()1. Introduction
Large-scale numerical simulation of soundfield in time domain has sometimes come to berequired in the field of the architectural acoustics orthe acoustic imaging. The geometrical sound field
analysis is usually applied to the large-scale
simulation, but it is difficult to achieve highaccuracy because the wave nature cannot be
included in the analysis. On the other hand, thewave nature can be included in the wave acoustic
analysis such as the finite difference time domain(FDTD) method1,2, but the huge amount ofcomputation resources is generally required toreduce the numerical dispersion error or thenumerical dissipation error.
To cope with the computation resource andthe numerical accuracy, the numerical method using
a combination of the finite element method (FEM)
and the boundary integral equation method has been
proposed3. In this method, the FEM is applied tothe small domain in which the wave analysis isrequired, and the boundary integral equation
method is applied to the other large field to obtain
the response at the required point. Using the
combination method, it is possible to achieve highaccuracy in the large-scale simulation. In thispaper, the combination method is applied to thesimulation of the acoustic imaging. The FDTD
method is applied to the small domain in whichtargets are located. The reflected waves from thetargets are calculated by the Kirchhoff boundary
integral equation method.
Some numericaldemonstrations are made in the two dimensional
field.
2. Theory
Two dimensional acoustic field is consideredas shown in Fig.1. The field is divided into two
domains; one is the FDTD domain  f and theother is the domain to be solved by the boundary
integral equation method  b . A virtual boundary is assumed between two domains.
The
transducer is located in  b , and the targets are
ttsuchiy@mail.doshisha.ac.jp

Fig.1 Two dimensional model.

located only in the FDTD domain.
The calculation procedure is as follows;
1) Calculate the incident wave for the input of
FDTD method on the virtual boundary  based on
the fundamental solution of 2-D sound field.
2) Analyze the wave propagation in  f by the
FDTD method and obtain the responses on  .
3) Calculate the reflected wave at the receiving
point by the Kirchhoff boundary integral equation.
2.1 Calculation of incident wave
The fundamental solution of 2-D sound fieldis given as follows4  (t  r /c)
H (t  d /c)(1) 2 (d,t) = 
dz =


4 ct

2 t 2  (d /c) 2

where r is distance between point source along line
source and observation point, c is sound speed, 
is Dirac’s delta function, d is distance between line
source and point on the virtual boundary and H is
Heviside step function. The input wave on thevirtual boundary is calculated as
 f
f
(2)
pi = 
 2 (d,t   )d = 2 (d,t)
0 



where f is driving waveform at the source. The
input waves are calculated at the FDTD grid points
on the virtual boundary, and the wave propagationin the FDTD domain is then calculated.
2.2 Calculation of reflected wave
The reflected waves from the target arecalculated on the virtual boundary by the FDTD
method. In the 3-D case, the response at thereceiving point is calculated by the following
Kirchhoch boundary integral equation5.

Fig.2 Numerical models.

Fig.4 B-mode images of one target.

 1 p 1 r p 1 p 
+
+
d

  r nr n r c t 

(3)where n denotes the normal line direction.
2-D case, the response is expressed as

In the

po =

1
4





p

r

(r ,t)1 r

p 

  2 (r ,t)  n + n 2ct  p + c n 2 (r ,t)  t d (4)where is r the distance between the virtualpo =boundary and the receiving point.
3. Numerical experiments
To verify the validity of the present method,some numerical examinations are made for thesound propagation in water. 2-D models are
considered as shown in Fig.2. Figure (a) shows
the FDTD model and (b) shows the model for the
combination method. The grid spacing  andthe time step t are chosen to be 1mm and0.33 μ s, respectively where CFL number is 0.5.
The sound speed c0 is 1500m/s and the medium
density  0 is 1000kg/m3. The domain issurrounded with the five-layered PML. A singleshot pulse of differential Gaussian shape is applied
to the transducer of 20mm in length. A target of
200mm in length, 10mm in width and 2000kg/m3 indensity is located in each model.
Figure 3 shows the calculated sound pressure
waveforms reflected from the target. Figure (a)shows the waveform when the transmitted pulse
width is 16.6 μ s and (b) 6.6 μ s. The two
calculated results well agree in the long pulse width,

Fig.5 B-mode images of two targets.

although the waveform calculated by FDTD
method collapses in the short pulse width becauseof the numerical dispersion error. On the other
hand, the numerical dispersion error hardly appears
in the result by the combination method because it
does not occur in the boundary integral equation
method.
To achieve a high-resolution image in acoustic
imaging, a short width pulse is necessary as muchas possible. However the indistinct image is
obtained by the FDTD method using the shortwidth pulse because of the numerical dispersion.
Figure 4 shows the B-mode images of the target
obtained by scanning the transducer. The image
obtained by the FDTD method is indistinct, whilethat by the combination method is clear. Figure 5
shows the case of two targets. By the FDTD
method it is difficult to distinguish each target,
while the two targets can be sharply distinguishedby the combination method. It is found that thepresent combination method is suitable for thelarge-scale simulation.
References
1. Y. Saito, T. Tsuchiya and N. Endoh: Jpn. J. Appl.
Phys. 45, 5B (2006) 4693.
2. M. Sato: Jpn. J. Appl. Phys. 45, 5B (2006) 4453.
3. S. Bunya and S. Yoshimura: J. Acoust. Soc. Jpn.
58, 12 (2002) 738 (in Japanese).
4. M. D. Greenberg: Application of Green’s
functions in science and engineering (Prentice-Hall,
New Jersey 1971).
5. Archi. Inst. Jpn.: Prediction of sound field inrooms: Theory, application and recent development(Archi. Inst. Jpn., Tokyo 2001).

Fig.3 Calculated waveforms reflected from the target.

2P10-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 335- 336
11-13 November, 2008

Phase Shift Keying Modulation with Impulse Response
for Ultrasonic Communication
通信系のインパルス応答を考慮した PSK 変調方式
Tadashi Ebihara1‡, Keiichi Mizutani2, Naoto Wakatsuiki1, Koichi Mizutani1, and Koichi
Morikawa3 (1Univ. Tsukuba; 2Tokyo Tech.; 3Univ. Tsukuba)

1
1 ms

0.5
0
0

Symbol time T
5 ms

1
0
-1 (a) PSK modulated signal
Guard time ΔT
1.25 ms

1
0-1 (b) PSK modulated signal with guard time

Time (10 ms/div)
Fig.2 PSK modulated signal and PSK modulated
signal with GT to reduce the affection of impulse.

SP

2. Modulation and system fabrication
2.1 PSK modulation method with impulse response
PSK is a digital modulation technique
whereby the phase of a carrier frequency is shiftedto represent a digital “1” or “0” state as follows,s 0 (t ) = A sin 2π f c t ⎫⎬, 0 ≤ t ≤ T ,s1 (t ) = − A sin 2π f c t ⎭(1)-----------------------------------------------------------ebihara@aclab.esys.tsukuba.ac.jp

5Time (ms)Fig.1 Impulse response observed from performance
evaluation system.

Relative Amplitude

1. Introduction
Recently, there has been an increase of
research in ultrasonic communication especially inunderwater environment1-4), because radio communication in underwater environment is a challenging
task due to the rapid attenuation of the electromagnetic spectrum. In contrast, ultrasonic communication in the air is not so often used because theyattenuate rapidly in the air. However, use ofultrasonic to communicate in the air is effective inshort-range communication5-7). An audible frequency acoustic communication method using
ubiquitous speakers and microphones has
advantages like availability of commercial audio
devices for and no regulation in frequencies.
On the other hand, existence of impulse
response distorts the waveform notably in the air
ultrasonic communication. To perform communication with low error rate, it is necessary toensure sufficient symbol time For example, there
are preceding studies that considers the relationshipbetween the length of symbol time and bit-error rate
(BER)8). Unlike the high-frequency communication that is able to ensure informationtransmission rate with sufficient symbol time, there
is a problem for low-frequency communication tobalance transmission rate and symbol time. To
achieve balance competing goals for transmission
rate and symbol time, reducing the affection of
impulse response is necessary.
This study was aimed at designing newphase shift keying (PSK) modulation for
low-frequency communication in the air. By
inserting guard time (GT) between symbols, it ispossible to reduce the affection of impulse responsein communication system.

Relative Amplitude

海老原格1‡, 水谷圭一2, 若槻尚斗1, 水谷孝一1 , 森川浩一3 （1筑波大院・シス情工; 2東工大院・理
工; 3筑波大・工シス）

L = 1.8 m

MIC

fc = 200 Hz
DAC

PC,
LabVIEW

ADC

Fig.3 Block diagram of a performance evaluation
system of acoustic communication in the air.

10

-1
-2

10

2.2 Performance evaluation system
We consider the performance evaluation
system for digital communication in the air asshown in Fig. 3. This evaluation system consists ofa personal computer (PC), digital to analog andanalog to digital converter (DAC, ADC), a speakeramplifier (SP Amp), a loudspeaker (SP), a microphone (MIC), a microphone amplifier (MIC Amp),and a sound propagation path. Transmission signal
is created and modulated by LabVIEW in PC.
Amplified transmitted signal from SP which iscontrolled by DAC, propagates the channel and isreceived by MIC. Amplified received signal
through ADC is added to white Gaussian noise anddemodulated by LabVIEW in PC.
3.

Experimental Results

The SP (FF-70EG, Foster) and the MIC(WM-62PC, Panasonic) were placed face-to-face inan anechoic chamber at the distance of 1.8 m. The
SP and MIC were controlled through DAC and
ADC (6062E, National Instruments) by the PC. The
transmitted data, whose length was 16 bit, wascreated randomly. Bi-phase shift keying (BPSK)
was used for modulation. The carrier frequency was
200 Hz and GT was 1.25 ms, in order to avoid theimpulse response effect in evaluation system asshown in Fig. 1. The experiment was performed bychanging signal-to-noise ratio (SNR). We define
SNR as follows
SNR = 10 log10 (ES / E N ) ,(3)
where ES is received signal power and EN is
additive white Gaussian noise (AWGN) power,
which was added to the received signal in PC.
Through this experiment, BER was calculated ineach SNR.

-3

10

-4

s 0 (t ) = A sin 2π f c t 0≤t ≤T + 0 T ≤t ≤T + ΔT ⎫⎪⎬ , (2)s1 (t ) = − A sin 2π f c t 0≤t ≤T + 0 T ≤t ≤T + ΔT ⎪⎭where ΔT is GT. From these expressions, PSK
modulated signal and PSK modulated signal withGT are shown in Fig.2. Figure 2 (a) shows PSK
modulated signal where T is 5 ms, and Fig.2 (b)shows PSK modulated signal with GT where T is 5
ms and ΔT is 1.25 ms, because notably impulse
response can be observed within 1 ms in Fig.1. By
inserting GT between symbols, we can avoid the
problem from impulse response more effectively.

0

10

BER

where s0 is a signal when data bit is “0”, s1 is “1”, A
is a signal amplitude, and T is a symbol time.
However, precipitous phase shifting distorts signal
due to impulse response as shown in Fig.1,
especially in bit-inverting point because impulse
response of communication system and transmitted
signal are convoluted. To avoid this problem, wesuggest inserting GT between symbols as follows

10

BPSK (Ideal)
BPSK
BPSK with GT

-5

10

-30

-25

-20

-15

-10

-5

0

5

SNR (dB)
Fig.4 BER performance of BPSK modulated signal
and BPSK modulated signal with GT observed inperformance evaluation system.
Figure 4 shows the BER performance in casethat the transmitted signal is as shown in Fig.2 (a),and Fig.2 (b). Ideal performance was drawn in
dot-line, experimental result from BPSK was inchain line, and experimental result from BPSK with
GT was drawn in continuous line. In the simulation,
we do not consider about signal distortion caused
by impulse response of performance evaluation
system, and the received signal is ideallytransmitted through AWGN channel. From Fig.4,
BPSK with GT achieves BER 10-3 at -5 dB whennormal BPSK achieves at -0.5 dB. Moreover, when
SNR is -5 dB, BER of BPSK with GT is about 10-3,
and normal BPSK is about 10-2. The obtained
results from Fig.4 suggest that by inserting GT
between symbols, we can improve SNR at same
BER about 4 dB, and BER at same SNR about 10
times. Consequently, by inserting GT between
symbols, it is possible to reduce the affection of
impulse response in communication system.
4.

Conclusion

New PSK modulation method to reduce theaffection of impulse response was proposed. By
inserting guard time whose length is 25% of symbol
time, we could improve BER at same SNR
effectively. Considering relationships between
transmission rate and symbol time is our future
work.
References
1. M. Stojanovic: IEEE J. Oceanic Eng. 21 (1996) 125.
2. H. Ochi et al.: Jpn. J. Appl. Phys. 39 (2000) 3184.
3. M. McCord et al.: J. Acoust. Soc. Am. 115 (2004) 2507.
4. Y. Watanabe et al.: Jpn. J. Appl. Phys. 44 (2005) 4717.
5. A. Ward et al.: Trans. IEEE. Personal Com. 4 (1997) 42.
6. N. Priyantha et al.: Proc. MOBICOM (2000) 32.
7. L. Chuan et al.: Trans. IEEE. Ultrason. 55 (2008) 908.
8. K. Mizutani et al.: Jpn. J. Appl. Phys. 44 (2005) 4541.

2P10-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 337- 338
11-13 November, 2008

Locality of Area Coverage on Acoustic Communicationin Air using Differential Phase Shift Keying
差動位相偏移変調を用いる空中音響通信における通信領域の局所性
Keiichi Mizutani1‡, Tadashi Ebihara2, Naoto Wakatsuki2 and Koichi Mizutani2(1 Tokyo Institute of Technology; 2 University of Tsukuba)

水谷圭一 1‡，海老原格 2，若槻尚斗 2，水谷孝一 2 （1 東工大院 理工; 2 筑波大院 シス情工）

1. Introduction
Acoustic communication in underwater environment has often been studied1-5). In contrast,
acoustic communication is not often used in air environment, because airborne sound is not very effective compared with electromagnetic waves, particularly for long-distance communication6, 7). The
disadvantages include the problem of attenuationand slow propagation velocity. However, it may berather effective for short-range communication suchas acoustic beacon systems for autonomous robots
in small area8). An example of the autonomous robot control system using acoustic beacons is shownin Fig. 1. To setup the beacons close to each other,each communication area coverage of each beaconis required to be limited. Therefore a localization of
acoustic communication may be effective for theabove system.
In this paper, we experimentally evaluate alocality of area coverage on digital acoustic communication in air using differential phase shift keying (DPSK). At first, a propagation loss performance is evaluated using one transmitter and one
receiver in environmental noise of constant level.
Next, influences of interference from anothertransmitter are evaluated using two transmitters andone receiver.
2. System Fabrication
The experimental system using DPSK digital
acoustic communication is fabricated as shown in
Fig. 2. This consists of two transmitters, one receiver and environmental noise source. Transmitterconsists of a PC, a digital-to-analog converter(DAC) and a loudspeaker (SP). Receiver consists ofa PC, an analog-to-digital converter (ADC) and a
microphone (MIC). Architecture of the environmental noise source is same as the transmitter.
White Gaussian noise is transmitted from SP withconstant level at the receiver. The transmitter, thereceiver and the environmental noise source share
the PC and software programs although these are-----------------------------------------------------------mizutani@mobile.ee.titech.ac.jp

Acoustic beacon
Acoustic beacon
Autonomous Robot

Fig. 1 Example of the autonomous robot control system using acoustic beacons.
Environmental noise source
Transmitter-A

Transmitter-B

Receiver

0

0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Location of receiver and environmental noise source [m]

DAC

ADC
PC
Receiver and noise source location

Fig. 2 System fabrication of the experiment systemusing DPSK digital acoustic communication and location of the two transmitters, the receiver and the environmental noise source.

independent in practical application. Therefore, theclock of each component is naturally synchronized.
3. Experiment and Evaluation
The location of the two transmitters and thereceiver is shown in Fig. 2. Distance between thetransmitters A and B is fixed to 4.0 m and theseare setup face-to-face. The receiver and the environmental noise source are located at 0.5, 1.0, 1.5,
2.0, 2.5, 3.0 and 3.5 (m) from the transmitter-A,and bit-error-rate (BER) is evaluated at the each
evaluation point. Transmitted power of the transmitters-A and -B are configured so that signal-to-noise-ratio (SNR) becomes -4.0, 0, 4.0, 8.0

γ = -4dB
10

References
1. D. P. Konstantakos, C. C. Tsimendis, A. E.
Adams and B. S. Sharif: IEE Proc. Commun..
152 (2005) 1031.
2. T, Kikuchi, H. Saito, T. Tsuchiya and Y. Hiyoshi:
Jpn. J. Appl. Phys. 44 (2005) 4708.
3. S. Lee, K. C. Park, J. R. Yoon and P. H. Lee: Jpn.
J. Appl. Phys. 46 (2007) 4971.
4. H. Ochi and T. Fukuchi: Jpn. J. Appl. Phys. 46(2007) 4961.
5. T. Shimura, H. Ochi and Y. Watanabe: Jpn. J.
Appl. Phys. 46 (2007) 4956.
6. H. R. Beom and H. S. Cho: Robotica 13 (1995)
243.

BER

10 -2

4dB
8dB

12dB

10 -3
10 -4
0.5

γ : SNR at location of receiver is 2.0 m

1.0

1.5

2.0

2.5

3.0

3.5

Location of receiver and noise source
Fig. 3 BER performance with only transmitter-A.

10 0

γ : SNR at location of receiver is 2.0 m

10 -1

γ = -4dB
0dB

10 -2

4dB
12dB
8dB

10 -3
10 -4
0.5

1.0

1.5

2.0

2.5

3.0

3.5

Location of receiver and noise source

4. Conclusions

Fig. 4 BER performance with only transmitter-B.

10 0
10 -1

BER

Locality of acoustic communication using
DBPSK was experimentally evaluated. The cellradius of the transmitter could be limited under low
SNR condition. If another transmitter works, thecell radius was limited by effect of the interference
from another transmitter. The cell radius to distance
between the transmitter-A and -B was 22.5 % under
SNR was -4.0 dB if the BER at the cell edge wastaken as 10-2.

-1

0dB

BER

and 12.0 (dB) at the middle point of the transmitters-A and -B. Carrier frequency is 10 kHz,
one-symbol time is 0.8 ms, and modulation
scheme is differential binary phase shift keying(DBPSK), which are the same as our previous experiment8).
At first, BER performances are evaluated byemitting the transmission signal from only one
transmitter-A or -B. Area coverage of the transmitter is more limited as environmental noise level
becomes high. In this case, the cell radius is 0.9,
2.3 and 3.2 (m) under SNR is -4.0, 0 and 12 (dB)respectively if the BER is taken as 10-2 at the celledge.
Figure 5 shows the BER performance undercondition that both of the transmitters-A and -B
work. The signals from transmitter-B are independent of that from transmitter-A and the receivertries to demodulate signals from the transmitter-A.
BER performance deteriorates and cell radius islimited when the transmitted power of the transmitters-A and -B becomes high because transmitted waves emitted from undesired transmitter interferences in desired communication. However,under low SNR condition, BER performances aresame whether another transmitter works or not
because the environmental noise becomes dominant in such a situation. In this case, the cell radius
is 0.9 and 1.3 (m) under SNR is -4.0 and 0 (dB)respectively if the BER at the cell edge is taken as
10-2.

10 0

4dB

γ = -4dB

8dB
12dB

10 -2
0dB
10 -3
10 -4
0.5

γ : SNR at location of receiver is 2.0 m

1.0

1.5

2.0

2.5

3.0

3.5

Location of receiver and noise source
Fig. 5 BER performance with transmitters-A and -B.

7. L. Kleeman: Robotica 13 (1995) 87.
8. K. Mizutani, N. Wakatsuki and K. Mizutani: Jpn.
J. Appl. Phys. 46 (2007) 4541.

2INV1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 339- 340
11-13 November, 2008

High Temperature Ultrasonic Probes and Their Potential
Applications
高温超音波プローブ及びその応用可能性
Cheng-Kuei Jen † and Makiko Kobayashi (Industrial Materials Institute, National
Research Council Canada)†

任正魁 ，小林牧子 （工業材料研究所

カナダ国立研究所）

1. Introduction
Ultrasonic nondestructive evaluation (NDE)of materials, parts and structures [1-4] has played avital role in many industries involving improvementof reliablity, safety, service life extension,
maintenance cost reduction, etc. Increasingly
ultrasound is used for structural health monitoring(SHM) [3,5,6] for aerospace components, nuclear
and electrical power plants, petroleum plants,
engines, etc. For aerospace sector SHM facilitatescondition based maintenance to estimate theremaining useful life on a continuous basis and alsoenable modern light-weight aircraft designs withincreased safety and cost reductions. Also due to thehigh demand on non-stop supplying of energy,
SHM and NDE are crucial to extend the life span of
every nuclear power, electric power and petroleum
plant, and land based engines, the time span
between two adjacent showdowns for plant andengine inspections and also each shutdown time.
Furthermore, globle market demands high quality
products
manufacturedbycost-effective
technologies and technical specifications are
increasingly advanced and precise. The required
qualitycontrolfor
thesemanufacturing
technologies desires on-line process diagnostics(OPD) [4,7]. Ultrasound is one attractive OPD
approach. This study involves NDE, SHM and OPD
using ultrasound at high temperatures (HT) [1-7].
2. HT transducers and buffer rods approaches
Two approaches to achieve HT ultrasonicmeasurements are used. One is to use HT thick(>30µm) film ultrasonic transducers (UTs) made bya sol-gel spray fabrication process [3,5,6,8]. It
consists of six main steps: (1) preparing highdielectric constant solution, (2) ball milling ofpiezoelectric ceramic powders to submicron size,(3) film spraying using slurries from steps (1) and(2) to produce a layer of piezoelectric composite
ceramic film, (4) heat treatment to produce a solid
film, (5) corona poling to obtain piezoelectricity,and (6) top electrode fabrication. Steps (3) and (4)are used multiple times to produce proper
piezoelectric film thickness for optimal ultrasonic-----------------------------------------------------------Cheng-kuei.jen@cnrc-nrc.gc.ca

operating frequencies. In this operating frequencies.
investigation lead-zirconate-titanate (PZT) solution
is used for step (1). Piezoelectric PZT, bismuth
titanate (BIT) and lithium niobate (LN) powders areused for the fabrication of HT piezoelectriccomposite film PZT/PZT, BIT/PZT and LN/PZT
ultrasonic transducers (UTs) to operate reliably up
to 150°C, 450°C, 750°C, respectively. They can bedirectly coated and used as integrated UTs (IUTs).
If the substrate is thin, then such HT UTs can bemade as flexible UTs (FUTs) [8]. All HT IUTs and
FUTs can be used for SHM and NDE of objects
with curved surfaces [3,5,6,8].
Another approach involves the use of HT
delay line buffer rods. In this investigation cladbuffer rods consisting of core and cladding [2,7]and non-clad buffer rods [1,3,9] are used. The
advantages using buffer rods is that the temperatureof the probing end can be much higher than the UT
end. The well known issues to use the long delayline buffer rods are the presence of spurious echoes
due to one or more of: mode conversion, wave
reverberation and diffraction within the rod of finite
diameter. These echoes are unwanted because of
their possible interference with the desired signals
from the measured sample. These noises can be
reduced significantly using clad geometry [2,7] andtapered and/or thread shapes [9], thus signals withhigh signal-to noise ratio (SNR) can be obtained. In
this study only longitudinal (L) waves are used.
3.

Different HT UTs and ultrasonic probes

The evaluation of the ultrasonic strength of
all HTUTs and probes will be based on acommercially available EPOCH (model LT)
pulser-receiver device which has receiver gain up to
100dB. This handheld device is commonly used in
the NDT industry. The electrical contacts during allmeasurements were carried out using aspring-loaded two- pin probe. Fig.1 shows a 79µm
thick BIT/PZT film IUT deposited onto a steel
substrate of 12.7 mm thick and measured by the
EPOCH device at 400°C. At 400°C 47.4dB gain,out of the available 100 dB receiver gain was used
to produce the 1st echo reflected from the end of

the plate. The centre frequency and the 6dB
bandwidth are 5.5MHz and 4.6MHz respectively.
Fig.2 shows that the HT IUTs shown in Fig.1 areused as sensors incorporated into mold (or die)inserts for OPD of polymer injection molding (IM)[7] and light-weight metal IM or die casting.

25.4mm

12.7mm Thick

Fig.2 Four HT IUTs

BIT/PZT film IUT onto two non-clad tapered rods
and a clad steel buffer rod, respectively. Theircenter frequencies are near 5MHz. The former two
are used for OPD of polymer extrusion [7] without
the need of any cooling. It may be used from thefeed hopper down to the extruder die. The latter isused as the immersion HT UT for the remaining
wall thickness profile measurement of the container
inside the 450°C molten zinc. The steel wall
thickness is normally 60mm. Thickness reduction iscaused by the corrosion which may be
unpredictable due to uneven heating profile. Suchthickness measurement is one of the most important
NDE for hot-dip galvanization industry.

Amplitude (arb. unit)

L1
L2

5

10

L3

L4

Fig.4 Signals at 300°C.

When a clad buffer rod consists of a 12.7mm
steel core and 1mm thick stainless steel cladding as
shown in Fig.5 is used together with a 106µm thick
150°C PZT/PZT IUT deposited onto its one end,
the measurement setup shown in Fig.6 demonstrates
that the probing end of the clad rod can operate at ahigher temperature (182°C). If the length is longer,
the probing temperature can be higher. In Fig.6 at
151°C only 10dB out of the available 100dB
receiver gain of EPOCH was used. At 150°C thecentre frequency and the 6dB bandwidth of the L1
echo were 7.0MHz and 5.9MHz, respectively.

102 mm

14.7mm

ProbingEnd

Fig.5 PZT/PZT IUT on aclad rod.

97mm

76.2mm

Fig.7 PZT/PZT IUT with
non-clad rod.

4.

Fig.8 BIT/PZT IUT withclad rod

Conclusions

HTUTs including BIT/PZT and PZT/PZT IUTs or
FUTs made by sol-gel sprayed techniques can beused for SHM and NDE purposes. Together withmetal plate, clad and non-clad buffer rod delay lines
they can be used as mold (or die) insert sensors for
OPD of polymer or metal IM and polymer
extrusion, and container wall thickness profile
measurement in molten zinc.

15

Time Delay (µs)

Fig.1BIT/PZT FUT at 303°C.

14.7mm

Fig.3 shows the HT measurement setup of a
FUT having a ~70µm thick BIT/PZT film deposited
onto a 38µm thick stainless steel which is bonded
onto a 12.7mm thick steel substrate using a metallic
adhesive at 303°C. The measured ultrasonic datagone through a high pass filter is presented in Fig.4.
Ln is the nth round trip L echo through the plate
thickness The centre frequency and the 6dB
bandwidth of the L1 echo at 300°C were 10.7MHz
and 8.2MHz, respectively. Using EPOCH 69dB outof the available 100dB receiver gain was used.

10mm

Fig.1BIT/PZT IUT at 400°C.

Fig.6 PZT/PZT UT at 151°C.

Fig.7 and Fig.8 show thick PZT/PZT and

References
1. T. Arakawa, K. Yoshikawa, S. Chiba, K. Muto,
and Y. Atsuta: NDT&E. 7 (1992) 263-272.
2. C.-K. Jen, J.-G. Legoux and L. Parent: NDT&E
33 (2000) 145-153.
3. M. Kobayashi and C.-K. Jen: Smart Mat.
Structures 13 (2004) 951-956.
4. S.P. Kelly, D. Babcock, I. Atkinson, C. Gregory
and K.J. Kirk: Proc. IEEE Ultrasonics Symp.
(2007) 904-908.
5. M. Kobayashi, C.-K. Jen, Y. Ono, K.-T. Wu and I.
Shih: Jpn. J. Apl. Phys. 46 (2007) 4688-4692
6. Q. Liu, K.-T. Liu, M. Kobayashi, C.-K. Jen and
N. Mrad: Smart Struct. Mat. 17 (2008) 045023.
7. C.-K. Jen, Z. Sun, J. Tatibouët and Y. Ono:
Chap.3 in Ultrasonic and Advanced Methods for
NDT, World Scient. Publ. NJ (2007) 57-77.
8. M. Kobayashi, C.-K. Jen and D. Lévesque: IEEE
Trans. UFFC 53 (2006) 1478-1485.
9. C.-K. Jen, L. Piche and J.F. Bussiere: J. Acoust.
Soc. Am. 88 (1990) 23-25.

2INV2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 341- 342
11-13 November, 2008

Bubbles and Ultrasound:
A New Partnership for Medical Imaging
Peter N. Burns(Departments of Medical Biophysics and Radiology, University of Toronto)
An enduring challenge in medical imaging has
been the detection and imaging of perfusion at thecapillary level of the circulation. It is here, acrossthe hundreds of millions of microscopic vessels intissue, that exchange of oxygen and nutrients thatsustains viability takes place. Knowledge of theintegrity of perfusion in the myocardium is central
to the understanding of acute heart disease, in thebrain of stroke and less obviously, in a cancer of theproliferation of blood vessels known asangiogenesis. A technique that can image perfusion
offers an aid to both the diagnosis of heart disease,stroke and cancer and their treatment andsubsequent monitoring. Contrast imaging forultrasound seeks to provide such a method.
After more than 20 years of development and asomewhat hesitant start, microbubbles have finallycome of age as a contrast agent for ultrasound. The
bubbles themselves comprise small spheres of a gas
with low solubility in blood - such as aperfluorocarbon - stabilised by a thin shell layer ofa flexible, biocompatible material. This is typicallya lipid, though proteins and polymers are also used.
The diameter of the resulting encapsulated bubble isabout 3-5 µm, slightly smaller than a red blood cell.
A suspension of bubbles in water is injected into aperipheral vein in the arm or hand. A typical wholebody human dose is only about few million bubbles,
about the same as the number of red blood cells in asingle microlitre of blood. Partly because of thisextremely low dose, injections of microbubbles arevery well tolerated and have an excellent safety
record.
The objective of perfusion imaging in ultrasoundis to detect and segment the component of the echo
due to blood and use this to form a real-time imageof the distribution of blood vessels. While Doppler
works well as a way of identifying blood where
there is sufficiently fast flow in relation to tissue
movement, in the vast majority of the vascularsystem, the blood is moving at a speed comparable
to natural tissue motion. The blood-born bubbles
provide a distinct acoustic ‘label’ for theidentification of the vascular echo that is
independent of flow velocity: the challenge for-----------------------------------------------------------Burns@sri.utoronto.ca

contrast imaging is to create a method for its
detection and display. It is a fortuitous andunintended consequence of the choice of the size of
bubble that it displays a radial resonance between
about 3 and 5 MHz, which lies in the diagnostic
range of ultrasound frequencies. Solving anequation first conceived by Lord Rayleigh one
hundred years ago suggests that bubbles may
undergo resonant excursions of several radii in adiagnostic ultrasound field: this nonlinear resonant
oscillation provides the key for the detection andseparation their echo from the much greater energy
from the surrounding tissue. Unlike their air-filled
predecessors, typical perfluorocarbon bubbles canbe driven into nonlinear oscillation which lasts overseconds or even minutes, creating a steady streamof harmonic echoes. A class of imaging methods
have been developed that exploits the coherence of
these echoes over many pulses. Unlike tissue
structures, which give rise to echoes that simply
mirror the incident pulse, bubbles responddifferently to the phase and amplitude of each pulse
they experience. It is therefore a relatively simple
matter to make an imaging method thatdifferentiates between tissue and these bubbles: one
simply sends a sequence of pulses of differing
phases and amplitudes. On receiving the echoesfrom this sequence, the receiver combines them in a
way that ensures that the ‘mirror-like’ echoes fromtissues combine to zero. What is left is then somecombination of the nonlinear components of the
bubble echo. Precisely what nonlinear components
are produced by a sequence of pulses can be
determined mathematically. For example, keeping
the amplitude of the pulse constant but changing thephase of alternate pulses by 180 degrees (known aspulse inversion imaging) produces an echo witheven order harmonics. On the other hand, keeping
the phase constant and changing the amplitude(known as power modulation imaging) detects odd
and even order nonlinear components, though atsome cost to the signal-to-noise ratio. Combinationsof amplitude and phase offer specific advantages.
Almost all diagnostic systems now use some formof this multipulse modulation processing in theircontrast-specific imaging modes. As long as thepeak negative pressure is kept low (less than about100kPa) so that the bubble is not disrupted by thepulses, real time imaging of perfusion can beachieved in many organ beds, including the
myocardium, liver, kidney, skin, prostate and breast,
even in the presence of tissue motion. Whereas thetechnology for bubble imaging in commercial
ultrasound systems has stabilised over the past few
years, clinical applications are currently
experiencing expansion, especially in tumour
imaging, which in turn presents new challenges forimaging methodology.
At least 3 million clinical contrast studies havebeen performed to date worldwide: clinicalapplications have focused on areas in which
ultrasound already plays an important diagnostic
role. In cardiology, contrast can aid visualisation of
the endocardium, especially important in wallmotion studies, and has been shown to improve theaccuracy of stress echo. It can also image andmeasure myocardial perfusion in real time, at rest
and with stress, with spatial resolution superior tothe current nuclear medicine standard. In radiology,
perfusion can be imaged in many organs, but work
has concentrated on the liver, where contrast canhelp characterise focal lesions with an accuracy
comparable to contrast-enhanced CT and MRI. It
also aids in lesion detection, in real time guidanceof interventions such as radiofrequency ablationand in monitoring response to new cancer therapies.
In tumour imaging, the target is the angiogenic, or
proliferating network of blood vessels that sustains
a developing cancer. Not only has the identificationof these vessels proven an important way to
distinguish a malignant from a benign lesion, thevessels themselves have become the objective of a
new class of molecular therapies that aim to inhibit
angiogenic formation. Such anti-agiogenic or
vascular-disrupting drugs have the effect of shutting
down the tumour circulation and inhibiting further
growth. They do not in themselves kill cancer cells,
so the tumour often responds without shrinking insize, hence the need for a functional test to
determine drug response. Quantitative flow
measurement with bubbles is achieved by infusing
the agent to a steady level, then using a few highmechanical index pulses to disrupt and clear theimage plane of bubbles following whichmeasurement of its replenishment offers a unique
way to quantify microvascular flow and perfusion
volume. Models of the process are in development
to help improve accuracy.
Current development of the bubbles themselves
focuses on two main areas. In the first, the potential
for functional information yielded by the bubbles isincreased by active targeting to a specific cellular or

molecular process. Thus a bubble attaches itself tothe cells lining blood vessels (endothelial cells)
which are involved in a disease process such as
inflammation (in atherosclerosis) or proliferation(in cancer). This is achieved by attaching ligands tothe surface of the lipid shell, such as a peptide andan antibody. Antibodies to factors such as VCAM, amarker of inflammation and VEGF receptor, amarker of vascular proliferation, have already beenshown to effectively make bubbles ‘stick’
selectively to the endothelial surface. This form ofmolecular imaging has potential applications in
identifying the target and the effectiveness of new
therapies. In the second application, the bubbles areused as a potentiator of the therapy itself. Bubbles
can concentrate and lower the threshold for thermal
tissue damage in HIFU treatments. They can also
have the effect of opening or permeabilising theendothelial layer, allowing drugs to pass throughinto a region of tissue selected by the ultrasoundbeam. The drugs can be circulating in the
bloodstream, or incorporated into the bubbles
themselves. In the latter case, plasmid DNA, whichcannot survive in the blood, can be carried in the
bubble shell and released by acoustic disruption.
Oscillation of the free gas near the cell membrane
permeabilises it and allows the DNA to enter thecell. Both endothelial cells and myocytes have beensuccessfully transfected in this potentially new formof gene therapy.
These new applications pose many interesting
challenges to ultrasound imaging technology: Can
we quantify the number of bound bubbles? Can we
detect single bubbles bound to a single cell? Can we
distinguish bound from free bubbles acoustically?
Can we scale bubble-specific imaging to higher
frequencies? Answering such questions will assurethat ultrasound imaging of bubbles remains a richfield of enquiry in the foreseeable future.

2E7aProceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 343- 344
11-13 November, 2008

Separation of Nonlinear Ultrasound Signals
Based on Second-Order Volterra System Identification
Pornchai Phukpattaranont† (Facult. Eng., Prince of Songkla Univ.)

1. Introduction
We propose to investigate the application of asystem identification based on a second-order
Volterra filter (SVF)[1] to separate nonlinear signals
from a nonlinear pulse-echo ultrasound. In otherwords, we identify a nonlinear pulse-echo system(NPS) consisting of multiple scattering point targets(Fig. 1. upper block diagram) with the SVF
consisting of linear and quadratic kernels (Fig. 1.
lower block diagram). The objective is to apply theapproach on medical ultrasound applications, e.g.
ultrasound imaging enhancement and nonlinearity
parameter B/A estimation. This paper is focused on
developing an efficient implementation of the
input-output based system identification. In
addition, the preliminary evaluation results of theapproach are demonstrated and discussed.

Fig. 1 Identification of a nonlinear pulse-echo system(NPS) using a SVF model.

2. Nonlinear Pulse-Echo System
In this section, we present a model used to
produce radio-frequency (RF) lines from anonlinear pulse-echo system (NPS). Fig. 2 shows adiagram of a pulse-echo RF line generated frommedia with different nonlinearity parameter B/A.
The NPS model combines capabilities of the Field
II program [2] with the Khokhlov Zaboloskaya
Kuznetsov (KZK) equation [3]. The pulse-echo RF
data are generated in three steps: First, the spatial
impulse responses in transmissions are produced
from solutions of the KZK equation. Second, when
linear propagation and weak scattering are assumed,
the received RF pulse-echo signal resulting fromthe interaction of the transmitted pulse and ascatterer is determined. Third, a received pulse-echo
RF line is obtained by a weighted addition ofreceived RF signals from all scatterers in the regionof interest.
3. SVF System Identification
Identification of quadratic nonlinear system
algorithm is based on a digital method of modelingquadratically nonlinear systems with general
random input discussed in [4]. Representation of
the SVF in the frequency domain in term of thediscrete Fourier transform (DFT) of y(n) can be
expressed as-----------------------------------------------------------E-mail address: porncahi.p@psu.ac.th

Fig. 2 A diagram showing the generation of an RF linefrom a nonlinear pulse-echo system (NPS).
M

Y ( fk ) = H1 ( f k ) X ( f k ) +∑ H ( f , f )X ( f )X ( f )
2

i

j

i

j

(2)

i , j = − ( M −1)
i+ j =kwhere the linear transfer function H1(fk) and thequadratic transfer function H2(fi ,fj) are unknown. M
is the length of input sequence divided by two. Kim
and Power [4] proposed a general DFT-based
solution for the system identification problem using
higher-order spectra. We skip the details of thealgorithm, but state that (2) can be written in matrixform:
Y ( f k ) = xT h ,(3)where the vector h contains the coefficients H1(fk)and all H2(fi ,fj): i+j=k. To solve the variable h, bothsides of (3) are multiplied from the left by x* andthe expectation operator is applied resulting in

f = Gh,(4)where f = E[x*Y(fk)]and G = E[x*xT]. After the
linear and quadratic frequency responses are
determined, inverse discrete Fourier transforms(IDFTs) are applied to obtain the linear impulse
response h1(n) and the quadratic kernel h2(n1, n2).
4. Results and discussion
The parameters used in simulation are as
follows. The impulse response of the transducer is a
Gaussian-modulated sinusoidal pulse with center
frequency 3 MHz and fractional bandwidth 60 %.
The sampling frequency is 40 MHz. A single focus
at 70 mm is used in both transmission and reception.
The synthetic phantom is composed of scattering
particles located at uniform random positions in a
20 mm × 3 mm × 1 mm volume and Gaussian
distributed scattering strengths are assigned to thoseparticles.
To determine coefficients of linear andquadratic kernels, we form a system of linear
equations (Equation (4)) using average of frequency
responses resulting from 64 pseudorandom binary
sequences and their corresponding outputs from the
NPS. While each pseudorandom binary sequence iscomposed of 150 data points, each pulse-echo linefrom the NPS consists of 256 data points. Gaussian
white noise is added to pulse-echo data to achieve
the SNR of 50 dB. After the SVF kernels are
identified, we transmit a 3-cycle sinusoidal pulse at
2 MHz with a Hanning weighting to both systems,
i.e., the NPS and the SVF for validation.
Fig. 3 shows a simulated RF line from the
NPS using the dotted line. The pulse duration isapproximately 2.8 mm. In addition, thecorresponding spectra of time waveforms in the top
panel are displayed in the bottom panel. The 2nd
harmonics is clearly observed at 4 MHz. It can beseen that the linear kernel appropriately predicts thelinear output in the fundamental energy band(around 2 MHz). On the other hand, the quadratic
kernel captures energy primarily in the 2nd harmonic
and low frequency bands corresponding to second
order nonlinearity covering the whole transducer
bandwidth. This is the advantage of the SVF
approach over other static models such as linear
bandpass filters whose the sensitivity to nonlinear
separations is fixed to some specific frequencies,
e.g. the 2nd harmonic.
In addition, we found that the regularization
based on the truncated singular value
decomposition (TSVD) can reduce the number of
input sequences used in identification algorithm as

Fig. 3 Comparison of the pulse-echo line from the NPS(dotted) with the linear plus quadratic output from the
SVF model (solid).

Fig. 4 Quadratic outputs from the algorithm without(Top) and with (Bottom) TSVD regularization when thenumber of input sequences is decreased from 64 to 16.

shown in Fig. 4. Its advantage is to make theidentification approach more practical. The study
on computational complexity reduction is ongoing
research.
Acknowledgment
This research is funded by a grant fromThailand Toray Science Foundation and Faculty ofEngineering, Prince of Songkla University throughContract No. ENG-51-2-7-02-0004-S.
References

1 G.. L. Sicuranza: Proc. IEEE. 80 (1992) 1263.
2 J. A. Jensen and N. B. Svendsen: IEEE Trans.
Ultrason., Ferroelect., Freq. Contr. 39 (1992)
262.
3 Y. S. Lee and M. F. Hamilton: J. Acoust. Soc. Am.,
97 (1995) 906.
4 K. I. Kim and E. J. Powers: IEEE Trans. Acoust.,
Speech, Signal Processing, 36 (1988) 1758.

2E7b

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4     ?$*$  @  A"  B( A  0 *# #& $! && &# ) !  $  " !#!  %!  %  A"  +   #$ -..= ' 21C 34562/2)C7
    B(" D ?$  9$  +  EF ,  A"  B( A  E) !   #&4. !$   %#% #& !#!$ '# ( !( !# !  !#!#%"  "!## # ?9  A"  +   #$ -..= ' 21C 3456244)/=

USE2008
The 29th Symposiumon
ULTRASOICELECTRONICS

Thursday, November 13, 2008

3J2b-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 347- 348
11-13 November, 2008

Development of Ultraviolet-Excitation Photothermal
Microscope and Observation of Non-Stained Biological Cells
紫外励起光熱変換顕微鏡の開発と無染色生細胞の観察
Noriyuki Fujii‡ and Akira Harata(Dept. of Mol. and Material Sciences, Kyushu Univ.)藤井宣行‡, 原田明 （九大院総理工）1. Introduction
One of the Ultimate goals of analyticalbiochemistry is to detect certain target molecules ina living cell and to observe molecular behavior
in-situ. A fluorescence microscope is powerfultool for biological imaging with which the
distributions of fluorescent substances are observedwith ultrahigh sensitivity up to the single-molecule
detection level. Unfortunately, the greater parts ofbiologically important chemicals, such as aminoacids, nucleotides, proteins, hormones, and so on,
are nonfluorescent.
Thus, it is desirable todevelop ultrasensitive imaging methods fornonfluorescent compounds in and around a living
cell, so we aim to develop imaging methods for it
by improving performance of photothermal
spectroscopic method1).
Photothermal spectroscopy is one of the mostsensitive detection methods for nonfluorescentchemical species in a liquid solution. The thermallens method, one of the photothermal methods, issuitable for observing substances in biological cells
because it is based on the optical excitation andoptical detection of photothermal effects, and iseasy to use in combination with optical microscopy.
We have designed a new photothermal microscopeusing the third harmonics of the Ti:sapphire laser as
the excitation light source2). Position-selective
observation is achieved with newly equipping a
CCD system to the microscope, and distortion ofphotothermal image is discussed in observing
non-stained yeast cells (5 m in diameter) as
target.
2. Experimental methods
Figure 1 shows the schematic illustration of theexperimental setup for ultraviolet-excitation
microscopic photothermal lens imaging. The third
harmonic of a Ti:sapphire laser was used as theexcitation light source.
A thermal lens was
generated in a sample on a slide glass using-------------------------------------------------------------hr-n-fujii@mms.kyushu-u.ac.jp

Figure.1 Experimental setup for ultraviolet-laser
excitation microscopic photothermal lens imaging.
The photothermal lens signal is obtained from the AC
output of the photodiode; the transmitted lightintensity is monitored with DC output.

the third harmonics (260nm, < 1mW).
The
thermal lens signal was probed with thefundamental emission (780nm, < 3mW) of theTi:sapphire laser. Both excitation and probe laser
beams were focused using a reflection objective
lens (magnification, × 20; numerical aperture,0.38).
The
excitation
beam
wasintensity-modulated at 1.0 kHz with an
acousto-optic modulator. The probe beam waspassed through the sample. The light intensity at
the probe beam center was monitored with aphotodiode connected to an optical fiber.
Acolored glass filter set between the sample and theoptical fiber blocked the excitation beam. The
thermal lens signal monitored with a lock-in
amplifier was obtained from the AC output. The
photothermal amplitude Q and phase P arecalculated using
2

SOP

2

Q

S IP

P

arctan S OP /S IP

, where SIP and SOP are the in-phase andout-of-phase signal intensities, respectively. The
DC output of photodiode was used to monitor
transmitted light intensity.
The sample was set on an XYZ-mechanical stage
that was computer-controlled using laboratory-made software. Typically, a 60×60 m2 area was
obtained in 1 m scanning steps.
Position-selective observation is achieved with newly
equipping a CCD system to the microscope.
Accuracy of the x-y position was better than 3 m.
The samples used were yeast cells in the air or
glycerin on quartz plates. These cells were notstained. When we used yeast cells with glycerin,
the sample was covered with a quartz cover slip.

(a)

3. Results and Discussion
Figure 2 shows photothermal images of yeast
cells. Image (a) was an image of yeast cells in the
air and (b) was in glycerin. The contrasts of theseimages reflect the intensity of photothermal lenssignals. Both A and B in these images show CCD
images of the scanned areas (60×60 m2).
White area in the CCD image A is due to scatteredprobe beam. Three black spots are CCD imagesof 3 yeast cells. It can be observed from the images
A and (a) that the positions of the highphotothermal lens signals correspond to those of theyeast cells. This means that we could get thephotothermal lens signals of the yeast cells withultraviolet-laser excitation beam. However, thephotothermal lens signals show non-spherical shape,
though a yeast cell has a spherical shape. It isconsidered that the difference in refractive index
between a yeast cell and the air caused distortion of
the shape.
In Fig. 2(b), photothermal image of yeast cells inglycerin, some differences can be seen from image(a). First, photothermal lens signals were notalways observed even where we could see a yeast
cell in image B (CCD image). The signals wereobtained at two areas, though there were four yeast
cells in image B. It is suggested that photothermallens signals of some yeast cells could not be
obtained because of the height distribution: Eachcells in glycerin seems to be in a different height
above the quartz cover slip. Second, thermal lenssignals accompanied with a ghost signals. In atransmitted light image observed simultaneously(not shown), there were no change in thetransmitted light intensities at the position of theghost signal. The reasons why the ghost signals
are obtained are under investigation.

(b)
Figure.2 Photothermal amplitude images ofyeast cells. Area size is 60 × 60 m2.
Circumstances of yeast cells are (a) the air and(b) glycerin. Both A and B in this images show
CCD images of scanned areas, respectively.

4. Conclusion
For observation of non-stained biological cells,
we have developed an ultraviolet-excitation
photothermal microscope, with which position-selective observation of photothermal images ofyeast cells in both the air and glycerin are
successfully carried out.
Position of thephotothermal images well corresponded to that of
the CCD images. Although some distortions of
the cell shape as well as ghost are observed at thepresent stage, it is expected that this method has
great potential for the in-situ microscopy of
non-stained biological cells.
References
1. A. Harata, in ‘Nano Biophotonics: Science andTechnology’, Elsevier BV, pp. 73-92 (2007)
2. A. Harata, T. Matuda, S. Hirashima: Jpn. J. Appl.
Phys. 46 (2007) 4561

3J2b-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 349- 350
11-13 November, 2008

Imaging of Electromagnetic Properties via Ultrasound Waves
超音波による電気・磁気特性の画像化
Kenji Ikushima1, Hiraku Toida2 and Susumu Komiyama2 (1Dept. Appl. Phys., Tokyo Univ. of A &T; 2Dept. Basic Science, Univ. of Tokyo)

生嶋健司 1，樋田啓 2，小宮山進 2 （1 東京農工大

1. Introduction
Ultrasound technique is widely used tononivasively image human bodies and material
structures. However, the majority of existing
applications is restricted to diagnosing elastic
properties of the targets; viz., electromagnetic
properties are not probed. Piezoelectric imaging
techniques are highly developed in scanning probe
microscope systems,1,2 but only surface analysis istargeted. Recently, we have proposed anddemonstrated a distinguishing method of probing
electromagnetic properties of matters via
acoustic-wave excitation.3 In this scheme, electroor magneto-mechanical response of materials is
detectedthroughacousticallystimulated
electromagnetic (ASEM) radiation. Measurementsof such radiation are performed in wirelessoperation of acoustic-wave devices,4,5 but detectionof extremely weak ASEM radiation from materials
to be studied has been untackled.6 Utilizing a pulsed
ultrasoundtechnique,weprovedthatelectromagnetic waves are emitted from a variety ofmaterials when they are acoustically stimulated andthat the emission takes place even without themechanical resonance condition. The signal isfound in bones, woods, plastics, and ferrites as well
as a standard piezoelectric material of GaAs.3 In
this paper, we present imaging results of the ASEM
method for GaAs and a pure iron foil.

工; 2 東大院

総合文化）

kHz. ASEM waves picked up by the antenna are fed
to low-noise preamplifiers (a total gain of 97 dB)
and averaged over pulses by using a digital
oscilloscope. By moving the transducer with an
XYZ stage, the focal point scans over the wholearea of samples. Two-dimensional (2D) pictures of
ASEM radiation on picowatt levels are thus
obtained.
3.

Results

Figure 2 shows an ASEM image of semiconductor
crystals, in which piezoelectric materials are
selectively visualized. The samples are GaAs (110),
GaAs (100) and nonpiezoelectric silicon crystal.
The signals are detected with loop antenna (i) (Fig.

Fig.1 Schematic diagram of measurement setup.

2. Experiment
Figure 1 depicts the measurement setup.3 A target
sample is placed in a focused zone at a distance(about 40 mm) from a 10 MHz transducer, in which
rectangular 50 ns wide pulses are applied at arepetition rate of 200 Hz by a pulser/receiver(Panametrics-NDT, 5077PR). Noting the ultrasoundvelocity in water (1500 m/s), ASEM radiation
emitted by the sample is temporally separated by 27
μs from the apparent signal attributed to thetransducer, allowing unambiguous and sensitive
detection of true signal. The signals are detected via
loop antenna tuned to the center frequency ofultrasound waves with a bandwidth of about 200-----------------------------------------------------------e-mail address: ikushima@cc.tuat.ac.jp

Fig.2 Photograph (left) and ASEM image (right)of GaAs (110), GaAs(100) and Si(100) plates.

Fig.3 ASEM image of an iron foil: Original
sample (a) and one after folded (b).

1). Longitudinal acoustic waves are expected togenerate ASEM waves in GaAs when their wave
vector k is parallel to the piezoelectric axis of<110>. Thereby, ASEM signals at GaAs (110) plate
are definitely larger than ones at GaAs (100) plate.
Changing antenna configuration, we also found thatradiation distribution of GaAs (110) signals is well
explained by the interpretation of piezoelectric
polarization. The spatial resolution of about 0.6 mm
is determined by focal size of ultrasound waves.
Owing to the ubiquity of electromechanicalcoupling in matters, this measurement method may
find broad application in noncontact material
evaluation.
In addition to piezoelectricity, magnetomechanicalcoupling can be an origin of ASEM radiation.
Figure 3 (a) and 3(b) show images of a 0.1 mm
thick iron foil. The signals are detected by loop
antenna (ii). As seen in Fig. 3 (a), ASEM radiation
is found to occur along the sample edges,
suggesting the presence of magnetization. We
suppose that the observed signal arises from thealigned magnetic domains induced by external
stress or distortion when the iron foil is clipped. To
confirm the interpretation, we introduced external
distortion by folding the foil in the middle. The
radiation emerges along the middle line as shown in
Fig. 3 (b).
4.

Conclusion

We have demonstrated a unique method of
detecting and imaging electromagnetic response
induced by ultrasound waves. The method will
make it possible to implement nondestructive
tomographic imaging of electromagnetic properties
in matters as well as to obtain 2D spatial profiles.
Acknowledgment
This work was supported by Industrial Technology
Research Grant Program in 2006 from New Energy
andIndustrial
Technology
Development
Organization (NEDO) of Japan.

References
1. A. Gruverman, O. Auciello and H. Tokumoto:Annu. Rev. Mater. Sci. 28 (1998) 101.
2. S. V. Kalinin, E. Karapetian and M. Kachanov:Phys. Rev. B 70 (2004) 184101; S. V. Kalinin, B.
J. Rodriguez, S. Jesse, T. Thundat and A.
Gruverman: Appl. Phys. Lett. 87 (2005) 053901.
3. K. Ikushima, S. Watanuki and S. Komiyama:Appl. Phys. Lett. 89 (2006) 194103.
4. H. Ogi, H. Hiho and M. Hirao: Appl. Phys. Lett.
88 (2006) 141110.
5. M. Thompson, S. M. Ballantyne, L.-E. Cheran, A.
C. Stevenson and C. R. Lowe: Analyst(Cambridge, U. K.) 128 (2003) 1048.
6. Studies of EM radiation originated frompiezoelectricity of rock are reported ingeophysical researches, but the EM signals areproduced by rock fracture or high-pressure
experiments. For instance, S. Yoshida and T.
Ogawa: J. Geophys. Res. 109 (2004) B09204.

3J2c-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 351- 352
11-13 November, 2008

Ultrasonic Measurement of Closed Stress Corrosion
Crack Depth Using Subharmonic Phased Array
サブハーモニック超音波フェーズドアレイ SPACE を用いた
閉じた応力腐食割れの計測
Yoshikazu Ohara1†, Hiroaki Endo1, Tsuyoshi Mihara2 and Kazushi Yamanaka1(1Tohoku Univ.; 2Univ. Toyama)
小原良和1†，遠藤宏明1，三原毅2 , 山中一司1（1東北大工; 2富山大工）1. Introduction

3.

Nonlinear ultrasound has a potential of
becoming a primary means of evaluating closedwithcracks,andsubharmonic
waves1-4)
half-frequency of input wave are particularly useful
because of its excellent selectivity for closed cracks
and high temporal resolution. Thus far, we havedeveloped a novel imaging method, subharmonic
phased array for crack evaluation (SPACE)5,6), on
the basis of subharmonic waves and phased arrayalgorithm. In this study, we form more than 10 mmdeep stress corrosion crack (SCC), and image the
SCC in three positions using SPACE. Subsequently,
we precisely compare the SPACE images with theoptical images, and examine the relation between
optically- and SPACE-measured crack depths.

Although more than 10 mm deep SCCs havebeen observed in atomic power plants, it is difficult
to form such a deep SCC in the laboratory owing to
the low growth rate. In this study, we used new
method to form such a deep SCC.6) First, weformed approximately 10 mm deep fatigue crack in
an austenitic stainless steel specimen (SUS304
sensitized under 600 ºC for 4 h) with Kmax=28 and
Kmin=0.6 MPa m using a three-point bending
fatigue test. Subsequently, we extended the SCC
from the tip of the fatigue crack in a solution of 30
wt % MgCl2 at 90 °C for 650 h and at a nominal
bending stress of 124 MPa (Fig. 2).

Formation of a deep SCC

MgCl2 solution
30 wt.%, 90 ℃

2. Subharmonic Phased Array for Crack
Evaluation (SPACE)
Figure 1 shows the present implementation of
SPACE. Sensors are a LiNbO3 single-crystal
transmitter for generating intense ultrasound and a
receiving array for focusing on reception. By
inputting an intense ultrasound, fundamental waves
are scattered and subharmonic waves are generated
at open and closed parts of cracks, respectively.
These waves received by the array sensor are
digitally filtered at fundamental and subharmonicfrequencies. Subsequently, they are phase shifted
following delay laws and thereafter are summed.
Fundamental and subharmonic images can indicate
the open and closed parts of cracks, respectively.5,6)
Mother Clock
Burst Signal
Generator
Array
Sensor

LiNbO3SingleCrystalFilterCoefficientf, f/2ff（Fundamental image）

Open
Crack

Storage
Filter(f and f/2) Filtering

Delay Time
Extraction
Time…

A/D converter

Phase ShiftFPGA Summation
RMS
RMS
ExtractionPC

f/2（Subharmonic image）
ClosedCrack

Fig. 1. Experimental configuration of SPACE.

Fig. 2. Experimental setup for SCC formation.

4.

Imaging of the SCC with SPACE

To precisely visualize the branched SCC, weapplied SPACE to the SCC at three positions. The
input signal was a three-cycle burst of a 7 MHz
sinusoidal wave with a 10.3 nmp-p amplitude. We
used 64 elements in an array sensor with the center
frequency of 5 MHz. Furthermore, we selected a
configuration to receive both forward- andback-scattered waves from cracks, and focused on
reception with 0.1 mm step. Fig. 3 shows thefundamental and subharmonic images of the SCC at
positions A, B and C. A variety of crack images
were visualized depending on the positions. Thisshows that the SCC was complexly branched. Notethat the crack tips were deeper in subharmonic
images than in fundamental images at all positions.
This suggests that the tip of the SCC was closed.
After the measurement, the specimen was
sliced to thin plates to optically examine the depths
and distributions of the SCC (Fig. 4(a)). Fig. 4(b)(a) Position A (f)(b) Position A (f/2)

15.7

100

(c) Position B (f)(d) Position B (f/2)

15.3

16.6
13

(d) Position C (f)(e) Position C (f/2)

0

18.8

15.9
[mm]

Fig. 3. Dependence of the SPACE images of the SCC
on the measurement positions. (a) Fundamental and (b)subharmonic images at position A. (c) Fundamental and(d) subharmonic images at position B. (e) Fundamental
and subharmonic images at position C.
(a)

(b)

(c)

1 mm

Fig. 4. Optical observation of the specimen. (a) The cut
specimen to optically examine the SCC distribution. (b)The optical image of the cut cross section. (c) Schematic
illustration of shear stress field around crack tip.

(b) f/2

Crack tip in
fundamental
image
1 mm

Crack tip insubharmonic
image

Fig. 5. Superimposition of the optical crack image on
the SPACE images. (a) Fundamental and (b)subharmonic images.
20

f f/2

18

A
B
C

16

14
14

16

18

20

Optically-measured crack depth [mm]Fig. 6.
Relationship between opticallySPACE-measured crack depths of the SCC.

5.

17.3

Crack tip in
optical image(a) f

SPACE-measured crack depth [mm]shows an optical image of the cross sections. It wasobserved that the SCC was complexly branchedfrom the tip of the fatigue crack. Note that the SCC
was extended diagonally to the fatigue crack. Thismight be interpreted by assuming that the origin of
the SCC generation is a slip band in the high shear
stress area around the crack tip (Fig. 4(c)), although
SCC is generally extended under tensile stress.
To precisely compare SPACE images withcross sections, we superimposed the optical crack
image on the SPACE images (Fig. 3(d) and (e)) as
shown in Fig. 5. The crack tip in the optical image
was deeper than that in the fundamental image (a).
This causes the underestimation of crack depth. In
contrast, the crack tip in subharmonic image (b)was deeper than that in optical image. This suggests
thatsubharmonic
image
can
visualize
optically-unobservable closed crack.
To examine the measurement accuracy of
SPACE, the relationship between optically- andSPACE-measured crack depths is shown in Fig. 6.
The underestimation was reduced to be less than 1
mm in the subharmonic images, whereas it was 1.6
mm at the maximum in the fundamental images.
Thus we demonstrated that SPACE is useful in
reducing the underestimation of crack depths.

andConclusions

We formed more than 10 mm deep SCC, andprecisely imaged the complexly-branched SCC atthree measurement positions using SPACE. Afterthe measurement, we cut the specimen, anddiscussed the origin of the SCC extension. Wesuperimposed the optically-observed crack images
on the SPACE images. This suggests thatsubharmonic
image
can
visualize
optically-unobservable closed crack. By examining
therelationshipbetweenopticallyand
SPACE-measured crack depths, we demonstrated
that SPACE is useful in reducing underestimation of
crack depths.
Acknowledgment This work was supported by
Grants-in-Aid for Science Research from the
Ministry of Education, Culture, Sports, Science andTechnology of Japan, and by Japan Nuclear Energy
Safety Organization.
References 1) K. Yamanaka, T. Mihara and T.
Tsuji: Jpn. J. Appl. Phys. 43-5B (2004) 3082. 2) M.
Akino, T. Mihara and K. Yamanaka: Rev. Prog.
QNDE 23 (2004) 1256. 3) R. Sasaki, T. Ogata, Y.
Ohara, T. Mihara and K. Yamanaka: Jpn. J. Appl.
Phys. 43-5B (2004) 3082. 4) Y. Ohara, T. Mihara
and K. Yamanaka: Ultrasonics 44 (2006) 194. 5) Y.
Ohara, T. Mihara, R. Sasaki, T. Ogata, S. Yamamoto,
Y. Kishimoto and K. Yamanaka: Appl. Phys. Lett.
90 (2007) 011902. 6) Y. Ohara, S. Yamamoto, T.
Mihara, K. Yamanaka, Jpn. J. Appl. Phys. 47-5B(2008) 3908.

3J2c-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 353- 354
11-13 November, 2008

A Detection of Nonlinear Components of Lamb Wave
Generated from Closed Cracks
Using Double-Layered Piezoelectric Transducer
二層型圧電振動子を用いた
閉じた亀裂から発生する Lamb 波の非線形成分の検出
Makoto Fukuda‡ and Kazuhiko Imano (Faculty Eng. & Resource Sci., Akita Univ.)
福田誠‡，今野和彦（秋田大 工学資源）

1. Introduction

10-3

0

10-4

(a)

Phase [deg]Admittance [S]

90

10-2

10

-90

-5

0.5

1
1.5
Frequency [MHz]

2

10-1
90

10-2
10-3

0

10-4
10-5

(b)
0.5

1
1.5
Frequency [MHz]Phase [deg]Admittance [S]Ultrasonic waves have been widely used in
the non-destructive evaluation (NDE) of several
materials1,2). Recently, harmonic ultrasonic waves
have been employed as new tools for testingmaterials3-5). When materials are loaded withexternal force, closed cracks are generated inmaterials. This phenomenon can be one cause of thegeneration of nonlinear propagation of sound.
Closed cracks detection with subharmonic
ultrasonic waves has been studied5).
The authors have recently presented adouble-layered piezoelectric transdcuer (DLPT) inaligning polarization direction and subharmoniccomponents generating from plastic-deformed
metal rods have been detected6,7). In this study,
Lamb waves in a glass plate using our system are
generated and subharmonic components of Lambwaves generating from closed crack in the glass
plate are detected.

10-1

-90
2

Fig. 1. Frequency-Admittance characteristics of
DLPT electrically connected (a) in Parallel and (b) inseries. Solid lines indicate the absolute value ofadmittance and dotted line the phase of admittance.

2. Double-layered piezoelectric transducer
A double-layered piezoelectric transdcuer(DLPT) composed from a pair of PbTiO3
transducers with the same characteristics (resonancefrequency f0). The two transdcuers are stacked andbonded to one another in aligning polarization
direction. The resonance frequency of the DLPT is
f0 when the DLPT is connected in parallel; however,
it is f0/2 when the DLPT is connected in series. It is
possible to improve the receiving sensitivity of thesubharmonic components.
In order to generate S0-mode Lamb wave inglass plate (cL = 5800 m/s, cT = 3300 m/s)
effectively, ultrasonic waves are transmitted fromDLPT via a wedge (epoxy resin: cW = 2500 m/s).
The frequency-admittance characteristics of
the DLPTs, having the wedge, connected in parallel
and in series, as shown in Figs. 1(a) and 1(b),respectively. An effective fundamental pulse waves
transmission (1 MHz) is obtained when the DLPT iselectrically connected in parallel, while an effective-----------------------------------------------------‡

e-mail: mfukuda@gipc.akita-u.ac.jp

subharmonic pulse waves reception (500 kHz) is
obtained when the DLPT is connected in series.
3.

Experimental methods

The system for generating Lamb waves anddetecting subharmonic components using DLPT isshown in Fig. 2. The thickness of the glass plate
was 5.4 mm, and nanometer-order width of crack
existed in center of the glass plate. It has beenreported that second harmonic waves have been
generated from this glass plate and have been
detected in our eariler paper3).
Transmission signals were generated using afunction generator, and their amplitudes were
amplified to 150 V with a high-frequency power
amplifier. When DLPT was driven, DLPT wasconnected in parallel electrically. Ultrasonic pulse
waves were transmitted in the glass plate via thewedge, and then Lamb waves were launched in theglass plate. Lamb waves were reflected at the edgeof the glass plate. The reflected Lamb waves werereceived by DLPT connected in series electrically.

PC
GPIB

(a)

100

Amplitude [mV]

Trigger

Amplitude [mV]

Waveform
Generator

0-100High Frequency
AmplifierOscilloscope

50

100
Time [ μs]

0

-100

150

50

5.4 mm

120 mmFig. 2. Experimental setup.

The electrical connection of DLPT was
automatically controlled by an analog switch.
Finally, the received pulse waves were digitized andfed to a personal conputer via a general purpose
interface bus (GPIB).
4.

Results and discussion

Figures 3(a) and 3(b) show the waveform
and its spectrum received by our system from “nocrack area” of the glass plate, respectively. Wavelet
transform for the received waveform is carried out
as shown in Fig.4. Lapping dispersion curves ofgroup velocity of Lamb wave in glass over result of
wavelet transform, Fig.4 confirmed that the
waveform generated from DLPT was S0-mode
Lamb wave. Subharmonic components wereslightly
detected,
howeversubharmoniccomponents were approximately 40 dB smaller thanfundamental
components.
Subharmoniccomponents would be generated by contact acoustic
nonlinearity (CAN) at DLPT-wedge and/or
wedge-glass because the subharmonic components
were detected from “no crack area”.
On the other hand, Figs 3(c) and 3(d) show
the result of “closed crack area”. Subharmoniccomponents detected from “closed crack part” wereincreased approximately 5 dB compared with “nocrack area”. Change of amplitude of subharmoniccomponents will indicate the existance of the closed
crack.
In order to apply our system to NDE,
subharmonic components generation/detection ofanother mode of Lamb wave and imaging of cracks
will be required.
5.

Conclusions

A generation of Lamb wave in the glass plate
and a detection of subharmonic components
generated from the closed cracks using DLPT withthe layers having the aligning polarization
direction was demonstrated. Subharmonic(b)
Fundamental

-20
-40
-60
-80
0

Glass Plate

100
Time [μs]15020Subharmonic

Relative Amplitude [dB]

DLPT

SW

Relative Amplitude [dB]

20
0

(c)

100

1
2
Frequency [MHz]30Subharmonic(d)Fundamental

-20
-40
-60
-80
0

1
2
Frequency [MHz]3

Fig. 3. (a) The received waveform and (b) its
spectrum in no-crack area. (c) The waveform and (d)its spectrum in closed crack area.

300

A1

200
A0
100

S0
0

S1
1
0.5
Frequency [MHz]1.5

Fig. 4. Dispersion curves of group velocity of
Lamb wave in glass and result of wavelet
transform of received waveform.

components were detected approximately 5 dB at“no crack area” compared with “closed crackarea”.
In futute work, subharmonic components
generation and detection of another mode of Lambwave using DLPT will be required. Moreover,
several application that are imaging of cracks and acomparison between fundamental components andnonlinear components for imaging using our system
will be carried out.
References
1. K. Imano: IEICE Electr. Exp. 4 (2007) 340.
2. M. Watanabe, M. Nishihira and K. Imano: Jpn. J.
Appl. Phys. 45 (2006) 4565.
3. K. Imano and A. Muto: Sozai Busseigaku Zasshi
20 (2007) 12 [in Japanese].
4. K. Kawashima, M. Murase, K. Shibata and T. Ito:
Mater. Trans. 48 (2007) 1202.
5. Y. Ohara, T. Mihara and K. Yamanaka:
Ultrasonics 44 (2006) 194.
6. M. Fukuda and K. Imano: accepted to Acoust.
Sci. & Tech.
7. M. Fukuda, M. Nishihira and K. Imano: Jpn. J.
Appl. Phys. 46 (2007) 4529.

3J6-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 355- 356
11-13 November, 2008

Observation of bubble population phenomena
in sonochemical reactor
超音波反応槽内における気泡構造形成過程の観察
Yasuo Iida, Atsuya Towata, Kyuichi Yasui, Teruyuki Kozuka, Toru Tuziuti, and Judy
Lee (National Institute of Advanced Industrial Science and Technology (AIST))
飯田康夫，砥綿篤哉，安井久一, 小塚晃透, 辻内

1. Introduction
Single bubble dynamics have been theoreticallyand experimentally discussed in detail throughout
the life of the bubble. However, the dynamics of themultibubble system in the real sonochemical
reactors have been seldom studied experimentally
because of its complexity. In the multibubble
system, we should take into account the population
phenomena of bubbles; bubble-bubble interaction,
spatial structure, size distribution, and their number.
Sonoprocessing has been applied in industry
because of its unique features. We know that theefficiency can be proportional to the number ofactive bubbles, however we have little knowledge
on the control of the number of bubbles and theirdistribution in the reactor. We can find some
pioneering works upon this problem [1-3]. The
authors have reported the direct observation of
bubble dynamics in the microreactor to confine
bubbles under the observation field of a microscope[4, 5]. In this paper, we have tried to directly
determine the temporal development of the
population phenomena in sonochemical reactors;
Bubble size distributions were directly observed bylaser diffraction method. Bubble dynamics incavitation fields have been taken by a high-speed
video camera. A series of SL images were taken by
an intensified CCD camera. We will discuss the
bubble structure in multibubble system from thesound field dynamics, such as standing/travellingwave ratio and the related radiation forces, and the
bubble dynamics, such as initiation, coalescence,fragmentation and flow of bubbles. Both dynamics
are mutually affecting each other and leading to theinhomogeneous distribution of bubbles in asonoreactor.
2. Experimental
The ultrasound was emitted from a ceramictransducer (50mm diameter) through a stainlessbase fitted to the bottom of a glass vessel(100x100x120mm) which contained 1L of solution.
The bubble size distribution was measured with alaser diffraction particle size analyzer (Nikkiso,

亨, ジュディー・リー

Aerotrac SPR 7340). As the ultrasound waves
deflect the probing laser beam, bubble size wasdetermined during the off time of the pulsed
ultrasound irradiation. The bubble motions wereobserved with a high-speed video camera (Photoron,
FASTCAM-512PCI). The sonoluminescence (SL)images were captured by an intensified CCD
camera (Andor Technology, model DH501-18F-01).

3. Results and discussion
Figure 1 shows the development of the bubble
size distribution by the sequential burst ofultrasound. The cavitation bubbles have grown to
20 m of D50 by the first train of 20000 waves ofultrasound (100ms) via the coalescence phenomena.
The size of the bubbles decreased and somedissolved away during the OFF period. In thefollowing burst of ultrasound, both the size and thenumber of bubbles increased and the D50 reached
150m at the 9th burst. It was also shown that the
population growth was dependent on the burst
sequence. The long ON time and short OFF timeeffectively increased the size and the number of
bubbles. It should be noted that the active bubbles
are in the range of 1-10m for the ultrasoundfrequency used. The overgrown bubbles will be
expelled from the system as degas bubbles.
Therefore, the coalescence in this direction shouldbe negative to the activity of sonochemical
reactions. On the other hand, the coalescence in thefirst burst will help the tiny (dark) cavitation
bubbles from the fate of dissolution up to therectified diffusion limit [6]. Therefore, thecoalescence in this direction is positive to theactivity of sonochemical reactions. Video images
captured by the high-speed video camera supported
the population phenomena of the bubbles observedwith the particle size analyzer.
The active bubble structures in multibubble
system were studied by a series of SL images taken
by an intensified CCD camera. Figure 2 shows SL
structures at different dissolved oxygen (air)concentrations in water at 448 kHz and 22 W. The

Fig. 1 The development of the bubble size
distribution by the sequential burst ofultrasound.
acoustic pressure distributions were also obtained
along the centre of the reactor (Figure 3). The
observed active bubbles structures are determinedby the interacting dynamics of sound field andbubbles. The locations to where bubbles might
migrate and accumulate under radiation forces arecontrolled by the sound field structure. Bubble
accumulation will in turn affect the local soundfield through the processes of absorption, scatteringand shielding. These will in turn affect the bubble
size distribution through their influence on theprocesses of coalescence and fragmentation. In all,the strong SL near the liquid surface at higher air
content could be due to the damping of standing
waves by large coalesced bubbles and the increasein the transport of active bubbles to the liquidsurface by the radiation force from traveling wave
component. The increase in the SL intensity at themild air content can be attributed to an increase in
the number of active bubbles due to inhibition of
bubble coalescence and also an increase in the local
acoustic pressure due to the lower attenuation effect.
The increase in the local acoustic pressure caused
an expansion in the active cavitation areas.
Acknowledgment
This work is supported by a Grant from the
Ministry of Education, Culture, Sports, Science andTechnology, Japan.

Fig. 2 Sololumonescence structure at different
dissolved oxygen concentration. Continuous
sonication at 448 kHz and 22 W.

Fig. 3 : Acoustic pressure distribution at 448
kHz, relative to the first antinode at the liquidsurface for saturated water.
References

1. A. Henglein, R. Ulrich and J. Lillie, J. Am.
Chem. Soc., 111 (1989) 1974.
2. J. Lee, M. Ashokkumar, S. Kentish and F.
Grieser, J. Am. Chem. Soc., 127 (2005) 16810.
3. J. Lee, S. E. Kentish and M. Ashokkumar, J.
Phys. Chem. B, 109 (2005) 5095.
4. Y. Iida, T. Tuziuti, K. Yasui, K. Towata and T.
Kozuka, Ultrason. Sonochem., 14 (2007) 621.
5. J. Lee, T. Tuziuti, K. Yasui, S. Kentish, F.
Grieser, M. Ashokkumar and Y. Iida, J. Phys.
Chem. C, 111 (2007) 19015.
6. C. C. Church, J. Acoust. Soc. Am., 83 (1988)
2210.

3J6-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 357- 358
11-13 November, 2008

Effects of ultrasound exposure time on dispersion of
nanometer-sized diamond particles
超音波照射時間の変化によるナノダイヤモンド微粒子の分散への影響
Takeyoshi Uchida1†, Tsuneo Kikuchi1 Takahiro Aoki2 Norimichi Kawashima2 andShinichi Takeuchi2 (1NMIJ・AIST; 2Facult. Biomedical Eng., Toin Univ.)
内田武吉 1‡，菊池恒男 1，青木貴宏 2，川島徳道 2，竹内真一 2 （1 産業技術総合研究所; 2 桐蔭横浜
大 医工）

1.

Introduction

Recently, various forms of nanotechnology
have been studied, including application of suchtechnology to the development of fullerene orcarbon nanotubes. Our study focuses on the
improvementofdispersion
stabilityof
nanometer-sized diamond particles having a
primary particle size of about 5 nm1-3). Diamondparticles of this type are normally used for theultra-fine polishing required by medical or othertypes of precision equipment. For example, when
texturing a hard disk substrate, the texturing
profiles affect the final magnetic properties in thelongitudinal direction of the disk. However, thediamond particles aggregated to about 5 µm remainpresent immediately after manufacturing. The
aggregated diamond particles cause the scratch on
the substrate. Therefore, technology for dispersion
to the primary particle size is needed.
In this study, we attempted the dispersion of
nanometer-sized diamond particles by ultrasoundexposure. Before now, the diamond particles havebeen disaggregated to average particle size of about
100 nm in standing wave sound field4). Also, thedispersion stability of such diamond particles was
improved by high oxidation ability of active oxygen
species generated by ultrasound exposure. However,despite the improvement, the diamond particles are
not disaggregated to the primary particle size.
Therefore, we need to evaluate the various
conditionsofultrasoundexposurefordisaggregating to primary particle size. We report
the effects of variations to ultrasonic exposure times
in this paper.
2.

Experimental method

Figure 1 shows the configuration of ouremployed ultrasound exposure system, which
consists of a stainless-steel vibrating disk (2 mmthickness, 180 mm diameter) with a bolt clamped
Langevin-type transducer (HEC-45402, Honda
Electronics Co., Ltd.). The transducer was placed at
the bottom of a water tank（70 mm long, 70 mm

wide, 150 mm high). 30 mg of diamond particles
were added to 500 mL of distilled water, and the
diamond suspension was stirred thoroughly.
Ultrasound was irradiated to the diamondsuspension by use of the ultrasound exposuresystem shown in Fig. 1. A standing wave soundfield was then formed in the water tank.

Diamondparticlesuspension

Bolt clamped
Langevin-typetransducer
Power amplifier

Vibrating disk
Function generator

Fig. 1 Acoustic dispersion system for improvementof disaggregation and surface modification of
nanometer-sized diamond particles

In this paper, the diamond suspension was
exposed to ultrasound at 150 kHz. Average soundpressure in water tank; i.e., the average value ofsound pressure distribution at height of 10 mm fromthe vibrating disk, was controlled to 70 kPa. The
loop of the standing wave sound field was locatedat the height of 10 mm from the vibrating disk. The
height of the diamond suspension in water tank was
100 mm. Ultrasound exposure time was within therange of 20 s to 1200 s. Average particle size andparticle size distribution of the diamond particles
after ultrasound exposure were measured by meansof a size distribution measuring system (LS230
Beckman Coulter).
3.

Experimental results

Figures 2 and 3 show the effects of ultrasoundexposure time on average size and particle size
distribution of nanometer-sized diamond particles.

exposure time. Particle size distribution at 20 s and
60 s remained unchanged from the particle size
distribution
beforeultrasoundexposure.
Furthermore, as shown in Fig. 3, particle size
distribution at 1200 s shows smaller particle sizes
than those observed at 300 s. However, because oursize distribution measuring system has a lower
measurement limit of 40 nm, results below thatlevel could not be measured, so it is possible thatthe diamond particles exposed to 1200 s have beendisaggregated to an average particle size andparticle size distribution less than the lower
measurement limit.

Average particle size (µm)

5
4
3
2
1
0

4.
0

200 400 600 800 1000 1200 1400
Ultrasound exposure time (s)Fig. 2 Relationship between ultrasound exposure
time and average particle size of nanometer-sized
diamond particles

25

1200 s

220 s

Number (%)

20
15

60 s

300 s
10

20 s
5
0
0.01
0.01

0s
0.1
11
0.1
Average particle size (µm)
Average particle size (µm)

1010Fig. 3
Change in particle size distribution of
nanometer-sized diamond particles by ultrasoundexposure

The average particle size of the diamondparticles decreased with increasing ultrasoundexposure time. Deposition of the diamond particles
was observed at 20 s and 60 s, and the average
particle size produced by those ultrasound exposure
times remained unchanged from average particle
size before ultrasound exposure. Also, diamondparticles disaggregated to an average particle size of
about 100 nm at 300 s and 1200 s. These results
indicate that average particle size of the diamondparticles can be controlled by varying ultrasoundexposure time.
Next, particle size distribution of the diamondparticles was measured under increasing ultrasoundSummary

We studied changes in average particle sizeand particle size distribution of nanometer-sized
diamond particles caused by variations inultrasound exposure time. The diamond particles
had a primary particle size of about 5 nm, but
aggregated to about 5 µm immediately after
manufacture. Particles of this type were exposed toultrasound at 150 kHz in water tank, and ultrasoundexposure time was varied over a range of 20 s to1200 s.
Our results show that average particle sizeand particle size distribution of the diamondparticles changed with increasing ultrasoundexposure time. At exposure times of 300 s and 1200s, the diamond particles had an average particle size
less than about 100 nm. Furthermore, at 300 s and1200 s, the diamond particles had a narrow particle
size distribution in the nanometer range.
In our future work, changes to the zeta
potential of nanometer-sized diamond particles by
increased ultrasound exposure time will bemeasured as well, because zeta potential affects thedispersion stability of diamond particles. The
dispersion mechanism of the diamond particles byultrasound exposure will also be considered.
References
1. V. L. Kuznetsov, A. L. Chuvilin, Y. V. Butenko, I.
Y. Malkov, V. M. Titov: Chem. Phys. Lett, 222(1994) 343.
2. A. E. Aleksensky, M. V. Baidakova, M. A.
Yagovkina, V. I. Siklitsky, A. Y. Vul, H.
Naramoto, V. I. Lavrentiev: Diamond andRelated Materials,13 (2004) 2076.
3. A. V. Gubarevich, S. Usuba, Y. Kakudate, A.
Tanaka, O. Odawara: Jpn. J.Appl. Phys, 43(2003) L920.
4. T. Uchida, A. Hamano, N. Kawashima, S.
Takeuchi: Jpn. J. Appl. Phys. 44 (2005) 4553.

3J8-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 359- 360
11-13 November, 2008

V 型超音波モータを型超音波モータを用
モータを用いた高速高分解能
いた高速高分解能ステージ
高速高分解能ステージ
High speed and quick response precise linear stage system using V-shape transducer
ultrasonic motors
阿隅一将 1,2†，福永了一 1，藤村健 1，黒澤実 2 (1 太平洋セメント; 2 東工大）
Kazumasa Asumi1,2†, Ryouichi Fukunaga1 ,Takeshi Fujimura1 and Minoru Kuribayashi Kurosawa2(1Taiheiyo-Cement Corp., 2Tokyo Inst. of Tech.)
Maximum speed of 1.5m/s and 1nm positioning accuracy ultrasonic motors have been minimized and developed. By using a
V-shape transducer ultrasonic motor, a 10kg weight massive stage was driven. The stage speed reached at 0.2m/s with controlled
maximum acceleration of 3m/s2 for thrust of 30N. For the high speed and precise positioning, the driving mode of the transducers
changed from a resonance frequency drive, an impact inertial drive and a DC drive depending on the required speed, acceleration,
positioning stroke and resolution. The stage was driven 20mm distance from an initial position in static condition with 1 nm
resolution within 350ms.

1. はじめに型超音波モータの小型化
モータの小型化
2. V 型超音波モータの新規に作成した小型の V 型超音波モータをFig.1 に示す。V 型超音波モータは、ランジュバ
ン振動子 2 個を 90°V 型に配置してその端部を結合させた形状をしている。この振動子は HeadBlock 先端が前後に振動する「対称モード」と左右に振動する「非対称モード」があり、これら 2 つの振動が結合させるように設計されている。圧電素子には、電極間 7 層の一体焼成型のハード系 PZT を各 2 個計 4 個用いている。特性を落とさずに小型化するため、圧電素子の大きさはそのままとした。Head Block を極力小さく設計し、ナットに振動速度の遅いリン青銅を用いたことによって、ナット長を短くした。
Fig.2 にナット長を変えた時の各モードの共振
周波数を示す。超音波モータの駆動に必要な「対称モード」と「非対称モード」以外にも共振が現れた。FEM 解析とモータの振動を実測した結果からこの共振は Head Block が上下に振動するモードであることがわかった。この振動を回避するためナット長を 21mm とした。
-----------------------------------------------------------†kazumasa_asumi@taiheiyo-cement.co.jp

Piezo elements

52mm

Head Block

Angled Block

92mm

Fig.1 New design for minimization of V-shape
motor.

44

Resonance Frequency (kHz)

超音波モータは、磁場を発生しない、ボール
ねじやギアなどの機構が不要となりコンパク
トにできること、などから電子線を使用する測長 SEM や電子線描画装置などの半導体製造装
置のステージの駆動機構として注目されている。しかし、小型の超音波モータの研究は多い
1,2,3)
ものの、高速かつ高分解能な超音波モータの研究は少ない。筆者らはこれまでに、高速かつ高分解能であるランジュバン振動子を 2 個用
いた V 型超音波モータについて報告してきて
おり 4,5,6)、1.5m/sec 以上の速度と 1nm の分解能を両立している。本報告では、比較的大きかった V 型超音波モータの小型化を試みた。また小型化した V 型超音波モータを用いて、可動部10kg のステージを駆動し、特性を測定した結果を報告する。

42
40
38
36
16

Symmetric
Asymmetric
Spurious

18
20
22
Nut Length (mm)24

Fig.2 Resonance frequencies shift by changing nut
length.
3. 小型化した
小型化した V 型超音波モータの型超音波モータの特性
モータの特性小型化した V 型超音波モータについて、速度と推力を測定した。可動部 1kg ステージを用い、38.5kHz で 100Vrms を印加した時の速度と加速度を測定し、推力を算出した。Fig.3 にその結果を示す。最高速度は 1.5m/sec を超え、推力は 40Nを示し、旧来の大きな V 型超音波モータと遜色ない値が得られた。また、DC 電圧駆動で 10nmのステップ駆動を行った結果を Fig.4 に示す。
位置センサには分解能 0.2nm のリニアスケール

を用いている。1nm 程度の分解能が得られ、10nm のステップ駆動が行えていることがわかる。

5. まとめ可動部 10kg のステージを速度 200mm/sec、加速度 3m/sec2、加加速度 90m/sec3 の S 字制御を行い、20mm 駆動した結果を Fig.5 に示す。コントローラは、はじめ共振周波数で駆動する高速モードを用い、移動プロファイル終了後、慣性駆動に切り替えて位置を追い込み、さらにDC 電圧で微動位置決めを行うよう、各駆動モードが自働で切り替わるようにプログラムしVelocity(mm/s)

1600
1200
800
400

10 20 30 40 50
Thrust(N)Position(nm)Fig. 3 Thrust-speed of V-shape motor

90
80
70
60
50
40
30
20
10
0
0

10 20 30
Time(sec)

Position deviation(um) Position(mm)Fig. 4 Step positioning of 10 nm.

V 型超音波モータの小型化を行い、速度や分解能を落とさずに約 40%の小型化を実現した。
速度は 1.5m/sec 以上、分解能は 1nm 程度であった。小型化した V 型超音波モータを可動部 10kgのステージを駆動したところ 20mm 駆動で約350msec で±1nm に静定することができた。
引用文献
1. T. Kanda, A. Makino, Y. Oomori and K.
Suzumori; ” A Cylindrical Micro-UltrasonicMotor Using Micromachined Bulk PiezoelectricVibrator with Glass Case”, Jpn. J. Appl. Phys. 45(2006) pp. 4764-4769
2. H. Tamura, K. Kawai, T. Takano, Y. Tomikawa, S.
Hirose, and M. Aoyagi; “Diagonally Symmetric
Form Ultrasonic Motor Using LiNbO3 Plate”,
Jpn. J. Appl. Phys. 46 (2007) pp. 4698-4703
3. Y. Doshida, S. Kishimoto, K. Ishii, H. Kishi, H.
Tamura, Y. Tomikawa, and S. Hirose; “Miniature
Cantilever-Type Ultrasonic Motor Using Pb-FreeMultilayer Piezoelectric Ceramics”, Jpn. J. Appl.
Phys. 46 (2007) pp. 4921-4925
4. M. K. Kurosawa, O. Kodaira, Y. Tsuchitoi, and T.
Higuchi, “Transducer for high speed and large
thrust ultrasonic linear motor using two
sandwich-type vibrators,” IEEE Trans. on
Ultrason. Ferroelectrics, and Freq. Cont., vol.45,
no. 5, pp. 1188-1195, 1998.
5. 阿隅一将, 福永了一, 黒澤実, “V-shape 2 bolt
clamped Langevin-type transducer ultrasoniclinear motor”, 信学技報, US2006-91, PP.31-36,(2006-12)
6. K. Asumi, T. Fujimura, R. Fukunaga and M. K.
Kurosawa: "Improvement of the low speed
controllability of a V-shaped, two bolt-clamped
Langevin-type transducer, ultrasonic linear
motor", Proc. of Symp. on Micro-Nano
Mechatronics and Human Science, MHS2007, pp.
377-382, Nagoya, 2007.11

30
20
10
0
-10
20
10
0
-10
-20

300
200
100
0
-100
40
20
0
-20
-40
0

100

Fig. 5 10 kg stage motion.

200
Time(msec)

300

400

Position deviation(nm) Speed (um)

4. 10kg ステージ駆動特性
ステージ駆動特性0-10 0

た 6)。Fig.5 から約 350msec で±1nm に整定できていることがわかる

3J8-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 361- 362
11-13 November, 2008

Application of a novel cleaning equipmentusing ultrasonic waveguide mode to the post CMP cleaning- Cleaning efficiency of spot type shower 導波路管型超音波洗浄機用振動子の CMP 後洗浄への適用-スポット型振動子の洗浄評価Kazunari Suzuki1,2, Ki Han1† , Shoichi Okano1 , Jyunichiro Soejima1
and Yoshikazu Koike2 (1KAIJO CO., LTD.; 2Facult. Eng.,Shibaura Inst.of Tech.)
鈴木一成 1,2，潘毅 1†，岡野勝一 1 ，副島潤一郎 1，小池義和 2（1 カイジョー; 2 芝浦工大 工）

1. Introduction
Alongside recent efforts to increase processing
speeds of semiconductor devices, Al patterns havebeen replaced with Cu. As CMP has been used toform multilayer circuit, edge and back side cleaning
becomes important to remove contamination
perfectly at post CMP cleaning. The authors havebeen investigating post CMP cleaner that installed
spouting megasonic cleaning equipment (Spot typeshower).1) On the other hand, we proposed a novel
cleaning equipment using ultrasonic waveguidemode (we call MEGATUBE).2) This equipment has
a waveguide connect with transducer which has asame structure of spot type. By applying thisequipment, it is possible to supply ultrasonic foredge and back side of substrate. However, it isconcerned to decrease the cleaning effect caused
from waveguide size. Firstly, we showed cleaning
efficiency of spot type and relationship between
dissolved gas concentration were investigated.

Fig.1 Configuration of the spot type transducer

2. Cleaning equipment for the post CMP
Chemical-mechanical planarization commonly
abbreviated CMP, is a technique used insemiconductor fabrication for planarizing a wafer.
After CMP, the number of particles over 0.20µm
diameter is about 1~4×104 per 8inch wafer. Brushscrub cleaning is applied on this surface to remove
these particles. After that, wafer will carry to thespin cleaning unit, precise cleaning by spot typeshower with megasonic (generate at 950kHz), rinseby DI water and spin dry will be applied.
Spot type shower consists of a PZT attached witha vibration plate, and reflection nozzle (SUS316L),
as shown in Fig.1. These parts were installed incase and sealed by packing. Cleaning solution (DIwater or chemicals) is supplied from a case andthroughout the waveguide. Ultrasonic waves
generate from PZT (vibration area is 15mm indiameter) are reflected between PZT and reflection
nozzle, waves are converged towards the center ofthe nozzle and emitted together with liquid flowing.
------------------------------------------------------------

We proposed a novel cleaning equipment using
ultrasonic waveguide mode.2) This equipment has awaveguide connect with transducer which has asame structure of spot type. The waveguide has aremovable structure, we can select the waveguidethat has a different length or bend shape according
to the purpose.
Fig.2 shows an advantage of waveguide typetransducer applied to the spin cleaning unit. At the
spot type, distance between nozzle and substrateshould be set up within 20mm to obtain optimum
cleaning effect. Therefore, it takes a lot of spaces onsubstrate to set up the transducer and arm. On theother hand, at the waveguide type, there is no needto set up the transducer and arm, so there is a freespace on substrate. By applying the input power tothe PZT, ultrasonic wave can be traveled along the
waveguide. It is possible to supply ultrasonic apartfrom PZT. And using the waveguide which has adifferent length or bend shape, it is possible tosupply ultrasonic for edge and back side ofsubstrate.

kz-suzuki@kaijo.co.jp

Inlet
Packing
Case PZT

Reflection nozzle
Substrate

To Generator

φ36

Outlet
66

θ

φ15

φ4

Detail of part A
unit : mm

Arm For top side

PZTFor edge
Forback side

20mm
PZT
Wave guide(DIW line)(a)Spot type(b)Waveguide typeFig.2 Application of waveguide type transducer tothe spin cleaning unit
10090

PRE [%] (≧0.2µm)

80
70
60

Sample : 8inch wafer
Contamination : Slurry for Cu (SiO2)
Particle size : ≧0.20µm
Recipe :Spin cleaning (DIW/Megasonic)
Spin dry_30sec

50
10s
20s
30s
40s
50s

40
30
20
10
0
0

5

10

15
20
Output Power[W]2530

Fig. 3 Output power dependence on particle
removal efficiency changing the cleaning time
100
90
80
70
60
50
40

15W

30

20W

20

25W
30W

10

Sample : 8inch wafer
Contamination : Slurry for Cu (SiO2)
Particle size : ≧0.20µm
Recipe :Spin cleaning_20sec (DIW/Megasonic)
Spin dry_30sec

0
2ppm

8ppm
12ppm
16ppm
Desolved N2 gas concentration [ppm]

20ppm

Fig. 4 Dissolved N2 gas concentration dependence
on particle removal efficiency changing the output
power
-1

10

f
Output voltage [mV]

4. Conclusion
We proposed an application of waveguide typetransducer to the post CMP cleaning. As a reference
to the waveguide type transducer, particle removal
efficiency using spot type was evaluated, and PREof 90% is obtained at 20W and 20sec or more. The
influence of dissolved N2 gas concentration in DI
water was carried out, and PRE becomes maximum
at 12ppm. Particle removal efficiency using
waveguide type transducer will be investigated.
References
1. S. Okano, T. Echigo, T. Osawa, T. Takano and O.
Takahasi : Kaijo Technical Report. 11 (2001) p. 26.
2. K. Suzuki, K. Han, S. Okano, J. Soejima andY. Koike : USE 2008 Symp. Ultrasonic Electronics.
(2008).[To be presented]
3. K. Tsukamoto : IDEMA Japan News 43 (2001) p.
7.

Free space

For top side

PRE [%] (≧0.2µm)

3. Cleaning efficiency of spot type shower
3.1 Output power and cleaning time
As a reference to the waveguide type transducer,
particle removal efficiency (PRE) using spot typewas evaluated. SiO2 particles were prepared as
contamination and put uniformly on wafer surface.
The number of particles on wafer surface is counted
by Inspection device (KLA-Tencor SP-1) and
0.20µm diameter is about 1×104 per 8inch wafer
after contamination. DI water was used as cleaning
solution. Flowing rate is controlled at 1L/min anddissolved N2 concentration in DI water is at 20ppm.
At the post CMP cleaning process high rate ofparticle removal have been required. Fig.3 shows arelationship between PRE and output power of spot
type changing the cleaning time 10sec to 50sec. The
larger PRE could be obtained with the larger output
power, and PRE of 90% is obtained at 20W and
20sec or more.
3.2 Dissolved gas concentration
At the megasonic cleaning, dissolved gas
concentration or kind of dissolved gas in cleaning
solution have an influence on PRE.3) The influenceof dissolved N2 gas concentration in DI water was
carried out. Fig.4 shows a result changing theoutput power 15W to 30W. In case of cleaning after
20 sec was investigated. At 12ppm of N2 gas
concentration, PRE becomes maximum in each
output power. It is thought to have a relation withexistence of cavitation. FFT analysis was carriedout to confirm existence of cavitation using ahydrophone probe (KAIJO 19001D). DI water
spouting from the waveguide will reach at thehydrophone and output voltage is measured byoscilloscope. Fig.5 shows FFT analysis result of
output voltage at 12ppm and 30W. From this result,harmonics(2f) and sub-harmonics(1/2f) wereconfirmed. They show existence of cavitation in DI
water.

-2

10

2f

-3

10

1/2f

-4

10

-5

10

0.0

500.0k

1.0M

1.5M

2.0M

2.5M

3.0M

Frequency (Hz)Fig. 5 FFT analysis result of a hydrophone probe
output (12ppm, 30W)

3J8-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 363- 364
11-13 November, 2008

Properties of Lead-Free Piezoelectric Ceramics and Its
Application to Ultrasonic Cleaner
無鉛圧電セラミックスと超音波洗浄機への応用
Tonshaku Tou1†, Yuki Hamaguti1, Yuichi Maida1, Haruo Yamamori1, Kazutoshi
Takahashi2, Yoshimitsu Terashima2, (1Honda Electronics Co., Ltd.; 2Fuji Titanium
Industry Co., Ltd. )董敦灼 1†，浜口佑樹 1，舞田雄一 1，山森春男 1，高橋和利 2，寺嶋良充 2 (1 本多
電子; 2 富士チタン工業）
1. Introduction
Pb(Zr,Ti)O3 (PZT) piezoelectric materials
have been widely used in actuators, sensors,
resonators and ultrasonic transducers because of its
superior piezoelectric properties. However, thetoxicity of lead oxide causes environmental
contamination.
Therefore, it is necessary todeveloplead-freepiezoelectric
ceramics.
Althoughthepiezoelectric
propertiesofceramics
havebeen(Bi0.5Na0.5)TiO3-based
investigated by many researchers 1,2), there is notreport about the properties which can be used as atransducer for ultrasonic cleaner.
We havedeveloped a new lead–free piezoelectric ceramics(Bi0.5Na0.5)TiO3-BaTiO3-(Bi0.5Na0.5)(Mn1/3Nb2/3)O3
which has good piezoelectric properties. 3) In thispaper, the high power characteristics of theceramics was reported.
The properties of abolt-clamp Langevin transducer (abbreviated as
BLT) using the ceramics was investigated. The
cleaning effect of ultrasonic cleaner using the BLTs
was evaluated.

sample, and subsequently fired at 600°C for 30 min.
The samples were polarized under 3 kV/mm bias at
120°C in a silicon oil bath for 20 min.
Cylinder sample was used to fabricate bolt-clamp
Langevin transducer (BLT) as shown in Fig.1. It
consists of two piezoelectric elements and two
metal blocks clamped at each end. In order toevaluate the cleaning effect, 15 BLTs wereassembled to a metal tank as 600 W type cleaner.
The piezoelectric properties of the samples were
measured by using an impedance analyzer(HP4194A). After measured the vibration velocity
of strip sample, electrical transient response4) wasused to evaluate high power characteristics. A
ultrasonic sound pressure meter (Honda electronics
HUS-5) was used to measure the intensity ofultrasound of the cleaner.
A aluminum foil of
0.01 mm in thick was used to examine the erosion
effect of the cleaner.

2. Experimental methods
A conventional process of ceramicengineering was used to prepare the sample. The
commercially available Bi2O3, Na2CO3, BaCO3,
TiO2, Nb2O5 powders, all of purity at least 99.0%
were used as raw materials. After the corresponding
metal oxides of the prescribed amount being mixed
by ball milling, 0.82(Bi0.5Na0.5)TiO3-0.15BaTiO30.03(Bi0.5Na0.5)(Mn1/3Nb2/3)O3 was synthesized byheating at 850°C for 2 hours, and then pulverized.
After formed at 190 MPa, sintered at 1150°C for 2
hours and machined, cylinder sample of 34 mm inexternal diameter, 14 mm in internal diameter and 5
mm in thickness was obtained. For the evaluationof high power characteristics, strip sample of 43
mm in length, 7 mm in width and 1 mm in thick
was fabricated by the same process. In order tomeasure the electrical properties, silver paste wascoated to form electrodes on both sides of the-----------------------------------------------------------ttou @honda-el.co.jp

Fig.1 Schematic diagram of the bolt-clamp
Langevin transducer (BLT).

3. Results and Discussion
Table 1 shows the dielectric and piezoelectric
properties of lead-free ceramics. Compare tocommercial hard PZT (Honda electronics HC50GS), we expect that lead-free ceramics can beused to ultrasonic cleaner. Figure 2 shows themechanical quality factor Qm of strip sample as afunction of vibration velocity. Both Qm decreased
with an increase in vibration velocity. However,Table 1.
kt

Properties of lead-free ceramics
Qm(%)

LeadfreeHardPZT

ε33T/ε0d33(pC/N)

tanδ

Tc

(%)

(°C)

41

500

110

520

0.66

260

45

1100

290

1200

0.50

320

kt: coupling factor, Qm: mechanical quality factor, d33:
piezoelectric constant, ε33T/ε0: dielectric constant, tan δ :dielectric loss, Tc: Curie point.

Intensity of ultrasound (V)Mechamical Quality Factor Qm(31 mode)

10000

1000

100
Hard PZT
Lead-free piezoceramics

10
0.1

1
Vibration Velocity Vop（ｍ/ｓ）

Figure 4 shows the intensity of ultrasound ofcleaner as a function of the distance from bottom of
the tank. Although they changed in the same way,
the intensity of ultrasound of cleaner using lead-freepiezoceramics is higher than that of hard PZT.
Figure 5 shows the erosion area of a aluminum foil
after it was sunk into the tank for 1 minute. The
erosion area was resulted from the cavitation ofultrasound. Because cavitation plays an importantrole to remove contaminants, the result suggeststhat the clean effect of cleaner using lead-free is
equivalent to hard PZT.

10

10
9
8
7
6

Hard PZT

Lead-free piezoceramics

5
4
3
2
1
0
0

Fig.2. Variation of the mechanical quality
factor Qm with the vibration velocity.

Vibration velocity Vop(m/s)

Qm of hard PZT decreased rapidly when thevibration velocity was over 0.5 m/s. On theother hand, Qm of lead-free ceramics did notchange rapidly when the vibration velocity wasless than 1.8 m/s. The result suggests that lead-freeceramics is suitable for the application of highpower.
Figure 3 shows the vibration velocity ofvibration surface of the BLT as a function of input
electric power. The frequency of the BLT is 28
kHz.
The vibration velocity of BLT using
lead-free piezoelectric ceramics was larger thanthat of commercial hard PZT at the same input
power although both of them increased with anincrease in power. It suggests that the power loss
in lead-free BLT is smaller than that in leaded BLT.
This result is correspondent to the relationshipbetween Qm vibration velocity as shown in Fig.2.
1.4
1.2
1.0
0.8

20 40 60 80 100 120 140 160 180
Distance from bottom of tank (mm)Fig.4. Variation of the intensity of ultrasoundFig.3.
bottom.
of the cleaner with distance from the bottom

(a)

(b)

Fig.5. Erosion area of aluminum foil after
sunk into the tank of cleaner. (a) Hard
PZT, (b) lead-free piezoceramics.
4. Conclusions
Lead–free ceramics 0.82(Bi0.5Na0.5)TiO3-0.15
BaTiO3-0.03(Bi0.5Na0.5)(Mn1/3Nb2/3)O3 has beendeveloped and applied successfully to ultrasoniccleaner. The cleaner has a high clean effect whichis good for commercial application.
References

0.6
0.4
0.2
0.0

Lead-free piezoceramics
Hard PZT（ HC-50GS）
0

5

10

15

20

25

30

Input power (W)Fig.3. Variation of the vibration velocity of
BLT (Bolt-clamp Langevin Transducer)
with the input power.

1) T. Takenaka, K. maruyama, K. Sakata, Jpn. J.
Appl. Phys., 30 (1991)2236.
2) H. Li, C. Feng, P. Xiang, Jpn. J. Appl. Phys., 42(2003) 7387.
3) T. Tou, Y. Hamaguti, Y. maida, H. Yamamori, K.
Takahashi, Y. Terashima: Japan Patent 4044944(2008).
4) M. Umeda, K. Nakamura, S. Ueha, Jpn. J. Appl.
Phys., 37 (1998) 5322.

3J8-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 365- 366
11-13 November, 2008

Acoustic Characteristics of High Frequency UltrasoundProbe using Piezoelectric Film Deposited by Aerosol
Deposition Method
PZT
Akito Endo‡, Jun Akedo (AIST ),

‡,

(

)

Introduction
In recent years, microscopical texture isdiagnosed using a 20 MHz to about 40 MHz. The
reason for using a high frequency ultrasound is for
improving distance resolution1) 2). In order to improvelateral resolution according to it, the small ultrasonictransducer of 100 µm or less is needed. However, thesensor was miniaturized, when it became the numberof high frequency further, attenuation was large, soundpressure required for an ultrasonic diagnosis was not
obtained, but the big subject that penetration distance(visual field depth) was insufficient occurred.
The aerosol deposition (AD) method is thedeposition process also with an easy detailed patternby not choosing the substrate quality of the material
3), but being able to form easily a piezoelectric film 1µm to 100 µm or more without adhesion layer, andusing a metal masker. Therefore, by this research, thePZT film deposited by the AD method annealing
temperature differs considered the influence which it
has on the sound pressure of a high frequency
ultrasound from10 MHz to 60 MHz.

Each annealing temperature and the film thickness areabout 30 µm. And each PZT films were poled at
250 ℃ at 30 kV/cm for 20 minutes and at 250 ℃ at
30 kV/cm for 20 minutes in air.
Acoustic velocity is considered to be about
3210 m/s from report that the density and Young’s
modulus of PZT deposited by the AD method areabout 7.76 g/cm3 and 80 GPa4). Therefore, in λ/4resonance, the resonance frequencies of the deposited
PZT films are considered to be near about 27 MHz to
29 MHz.
The dielectric permittivity (ε) and loss (tan δ) of
the each PZT film (at 0.5 V) were measured using animpedance analyzer (HP4194) at 100 kHz. The
dielectric permittivity (ε) and loss (tan δ) of thedeposited PZT film annealed at 600 ℃, 700 ℃, and
850 ℃The dielectric permittivity (ε) and loss (tanδ)of the deposited PZT film annealed at 600 ℃,
700 ℃, and 850 ℃ were ε :774, 780, 1030, and tan
δ 3.98 %, 3.91 %, 2.89 %.

2 Experimental Procedure
2.1 depositing condition and material property for
PZT films
The diameter 3 mm and thickness 0.5 mm
alumina substrate was used for the substrate fordepositing a PZT film. Ti/Pt was deposited on thesubstrate using RF spatter as a lower electrode. The
thickness of a lower electrode deposited 50nm oftitanium as a glue layer, deposited 600nm of platinum
as a electrode layer on titanium, and Ti/Pt were
deposited the thickness of 650nm on the alumina
substrate. The raw material used as a starting PZT
powder (Zr/Ti = 52/48) was the commerciallyavailable powder (PZT-LQ: niobium-modified PZT;
Sakai Chemical Ind.) with average particle size of 0.3
nm were used as starting powder.
The deposited PZT film was annealed at 600 ℃,
700 ℃, and 850 ℃ in air . Because, This was a low
annealing temperature which is the feature of theconventional AD film at 600 ℃
which apiezoelectric property recovers, it was taken as to
850 ℃ at which lead does not evaporate. Annealing
time of each PZT films were fired for 30 minutes.

The frequency response characteristic wasmeasured by the short pulse drive of each ultrasonicprobe and the frequency characteristic of soundpressure was measured using the needle typehydrophone (HNP-400, ONDA). The signal from afunction generator was amplified with power
amplifier (75W250W, Amplifier Research) withamplification 50dB, and was impressed to theultrasound probes. The transmitted ultrasoundpropagated underwater and received by the needle
type hydrophone. The received signal is amplified bya preamplifier(AH-2010-100, ONDA) with anamplification of 20 dB, and is displayed on an
oscilloscope (TDS2022B,Tektronix). In considerationof the Fresnel region, the probe and the hydrophone
were installed in 10 mm distance.

1

2.2 Experimental setup of ultrasound using
fabricated probe

3. Results and Discussion
The frequency characteristics of the soundpressure using each ultrasound probe is shown in
Fig.1. As for the resonance frequency of eachultrasonic probe, from the frequency characteristics ofthe sound pressure, the resonance frequencies as λ/4MHz or 60 MHz, the ultrasonic probe using the PZTfilm at 850 ℃ showed the value of the high soundpressure of 423 kPa at 40.5 MHz. Moreover, thesound pressure was overall high in the frequency of 10
MHz to about 50 MHz.

Amplitude (Arb. unit)

thickness mode were near 26 MHz to 27 MHz. And,the fluctuation in sound pressure is greatly found to all
ultrasound probes. The maximum sound pressures of
the ultrasonic probe using a PZT film at 600 ℃,
700 ℃, and 850 ℃ were 574 kPa, 1MPa, and 803
kPa. When each ultrasonic probes were compared, theultrasonic probe using a PZT film at 600 ℃ has
irradiated only the maximum sound pressure of 139
kPa at 40.5 MHz in high frequency band from 40
MHz to 60 MHz. However, the ultrasonic probe usinga PZT film at 700 ℃ has resonance frequencies of 40
MHz, 47 MHz, and near 55.5 MHz, and was set to
341 kPa, 384 kPa, and 248 kPa in high frequency
band from 40 MHz to 60 MHz. The sound pressure of
the ultrasonic probe using the PZT film at 850 ℃
was become to 423 kPa at 40 MHz and the almost
same sound pressure as the ultrasonic probe using the
PZT film at 700 ℃ was shown.

6.5

7

7.5
Time (µs)

8

8.5

(a)
1200
700℃

Frequency (M Hz)

850℃

0

800
600
400
200
0
0

10

20
30
40
Frequency (MHz)50

60

Fig. 1 The frequency characteristics of the soundpressure using each ultrasound probes
The transmission characteristics of ultrasoundprobe using the PZT fired at 700 ℃ , were
investigated using the impulse response by a pulse
drive. In order to investigate the frequency response of
the ultrasonic probe, the pulse of about 18 ns of pulse
width of amplitude 30.2 V was used. The received
waveforms and power spectrum of an received
ultrasound which were irradiated from the ultrasonicprobes using a PZT film at 700 ℃ is shown in Fig. 2.
They were found that the center frequencies were 27.1
MHz and the each fractional bandwidth (-3 dB) were
2.5 %.

4

10

20

30

40

50

0
Normalized power spectrum (dB)

Sound pressure (kPa)

600℃

1000

Conclusion

In the frequency characteristic of soundpressure, the ultrasound probe using a PZT film at
700 ℃ was able to irradiate the ultrasound of 1 MPa
at 27 MHz. Moreover, in the high frequency from 40

-10
-20
-30
-40
-50
-60
-70
-80

(b)
Fig. 2 (a) Received waveform and (b) normalized
power spectrum of the irradiated ultrasound by theultrasonic probes using PZT film annealed at 700 ℃.
Acknowledgement
This research was supported by the New Energy
and Industrial Technology Organization (NEDO) .
Referance
1) M.Ishikawa, M. K. Kurosawa, A. Endo, S.
Takeuchi, Jpn. J. Appl. Phys., 44 (2005) 4342
2) D. M. Mills and S.W. Smith: IEEE Trans. Ultras.
Ferroelectr. and Freq. Control 49 (2002) 1005.
3) J. Akedo and M. Lebedev: Appl. Phys. Lett. 77(2000) 1710
4) T. Miyoshi: Jpn. J. Appl. Phys. 46 (2007) 7018.

60

3P2b-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 367- 368
11-13 November, 2008

Visualization of the Wavefronts of Ultrasound Passed
through Bovine Bones
牛骨を透過する超音波波面の可視化による検討
Masahiro Ohno (Facult. Eng., Chiba Inst. Tech.)
大野正弘（千葉工大・工）1. Introduction
Ultrasonic diagnosis of osteoporosis has
attracted much attention in recent years.1)-5) In thestandard measurement system thus far reported,2)ultrasound was radiated towards a certain site of alimb (e.g., wrist) and the transmitted component
was detected to determine the values of soundvelocity and attenuation, which are believed to becorrelated with the value of bone density. However,wave propagation in human bones, which have
non-uniformly rounded surfaces as well ascomplicated inner structures such as trabecular
networks of cancellous bones, may not be a simple
process. If aberration is generated in the ultrasonicfield, errors will be introduced into the values to be
determined, into that of attenuation in particular. To
improve the precision of diagnosis, the spatial
structure of the ultrasonic fields passing throughsuch bones must be investigated. For this purpose,
we have tried to observe the wavefronts ofultrasonic beams passed through bovine bones by
the use of schlieren visualization technique.
2. Experimental Setup
Fig. 1 shows the fundamental part of theexperimental setup, which simply consists of a bone
sample immersed in water and an ultrasonictransducer irradiating ultrasonic waves towards it.
Two kinds of ultrasonic transducers were used, oneof which had a center frequency of 1.03 MHz and aradiation area of 10 mm in diameter, the other 3.5
MHz and 13 mm. Both of them had flat surfaces.
Ultrasound was irradiated in tone-burst waveforms
the duration of which was longer than 20 cycles. A
500 W power amplifier was used to boost thevoltage applied to the transducer. To visualize theultrasonic field distribution, this setup was placed ina standard schlieren system the optical axis ofwhich was oriented in the Z direction. The lightsource was a Xe stroboscopic lamp having anirradiation time as long as 180 ns, which was
sufficiently short to visualize the wavefronts ofultrasound both at 1.03 MHz and 3.5 MHz. The
light was monochromized by inserting awavelength filter centered at 500 nm.
-------------------------------------------------------------ohno.masahiro@it-chiba.ac.jp

The experiment was carried out in thefollowing manner. First, ultrasonic field distribution
was visualized and recorded without the bone
sample. Next, several bone samples, cortical orcancellous, were inserted in the ultrasonic path,then the images of the ultrasonic waves transmitted
through them were recorded. Since the attenuationof the ultrasound due to the insertion of the bone
was considerably high, irradiation power of theultrasound was set much higher in the latter case.
All the schlieren images were taken by detecting
zeroth order light (non-diffracted light). Thismethod is suitable for the present study, because it
allows any wavefront deformation to be visualized
as darkening against a bright background, while themethod by detecting the diffracted light permits
only a limited part of the wavefront deformation toappear in the picture owing to the pinhole's
selectivity to the diffracted light.
All the bone samples used were bovine bones.
Marrow part in the cancellous bone was removed
beforehand, and a special care was taken so as toreplace the hollow area of the trabecular structure
by water.
SAMPLE(BOVINE BONE)

AREA OFPHOTOGRAPHSWATERULTRASOUNDULTRASONIC
TRANSDUCER

YX

Fig. 1Z

Experimental Configuration

3. Experimental Results
Fig. 2 shows the experimental results for theultrasonic frequency of 1.03 MHz. All the images
show the field distribution in a 10 mm-squared area
25 mm apart from the transducer surface. Fig. 2 (a)shows the ultrasonic field in a free space (withoutsamples), which represents an undisturbed but

slightly diffracted wavefront pattern. Figs. 2 (b) and(c) are the wavefronts after propagating through a 7mm-thick cortical bone. Fig. 2 (b) is the result when
the ultrasound passed through the central part of thecortical bone, which shows a slight deformation(rounding) of the wavefronts. Fig. 2 (c), the result
for the case when the ultrasound traveled throughthe peripheral part of the cortical bone, represents
stronger wavefront bending and a beam deflection.
The result for a cancellous bone is shown in Fig. 2(d). The thickness of the sample was 18 mm. The
schlieren image shows small deformation, evensmaller compared to the field in a free space.
Fig. 3 shows the results for the 3.5 MHz
ultrasound. At this frequency, wavefronts wereseverely deformed after the beam had passed
through, even the central part of, the cortical bone(Fig. 3(b)). On the other hand, wavefronts emerging
from the cancellous bone (Fig. 3(c)) were as
straight as those in the free space. However, it
should be noted that the cancellous bone used inthis experiment was much thinner (7 mm) than thatused in the experiment at 1.03 MHz. No image wasobtained for an 18 mm-thick cancellous bone at 3.5
MHz because of the high ultrasonic attenuation.
4. Summary
The structure of ultrasonic waves that had
passed through bovine cortical or cancellous bones
has been observed by using the shilieren
visualization technique. Wavefront deformation in
the results for cortical bones can be attributed to therefraction at the curved interface between the bone
and water. On the other hand, results for thecancellous bones, which showed small deformation,need further investigation to be fully accounted for.
At present, we consider that the trabecular structureof the cancellous bone did generate a large amountof scattered waves, but they were hardly observableby the schlieren system because they diverged fromvarious points in the bone, and, resultantly, theremaining portion of the ultrasound was effectively
visualized.
References
1) I. Mano et.al.: Jpn. J. Appl. Phys. 46 (2007)
4858.
2) I. Mano et.al.: Jpn. J. Appl. Phys. 45 (2006)
4700.
3) T. Otani: Jpn. J. Appl. Phys. 44 (2005) 4578.
4) A. Hosokawa et.al.: Jpn. J. Appl. Phys. 36 (1997)
3233.
5) T. J. Haire and C. M. Langton: Bone 24 (1999)
291.

5 mm

(a) Without sample(b) Field passed througha cortical bone (1)(c) Field passed througha cortical bone (2)(d) Field passed througha cancellous boneFig. 2

Schlieren images of ultrasonic fields at 1.03 M Hz.

(a) Without sample(b) Field passed througha cort ical bone(c) Field passed througha cancellous boneFig. 3

Schlieren images of ultrasonic fields at 3.5 MHz.

3P2b-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 369- 370
11-13 November, 2008

超 音 波 CT 法 に よ る 内 臓 脂 肪 測 定 の フ ァ ン ト ム 評 価 実 験Phantom evaluation experiment of ultrasound CT for visceral fat
measurement
川本幸一郎‡, 山田晃, 田村美希（農工大院 生物シ応用科）
Koichiro Kawamoto, Akira Yamada, Miki Tamura (Grad. Bioappl. and Sys. Eng., Tokyo Univ.
of A&T)Sound speed reconstructive imaging for the human abdomen using transmission type computed tomography was studied, aiming at
the measurement of the visceral fat area for the metabolic syndrome diagnosis. In this paper, examinations were made to verify thevalidity and precision of the visceral fat area measurement based on experiment using a phantom specimen of human abdomen. As aresult, it was demonstrated that the reproducibility of the image and precision of the visceral fat measurement was almost satisfactory,
which can serve as the metabolic syndrome diagnosis.

1. Introduction

2. Principle of the visceral fat measurement
For the imaging of the human body
abdominal medium, the transmitter and receiverfacing pair transducers are arranged on the bodysurface. Travel time of the waves transmitted
through the abdominal medium for different
observation paths were collected. We assume thatthe travel time is proportional to the path integral of
the inverse sound speed of the medium along theconnecting path between the transmitter andreceiver based on the straight path propagation
model. On this assumption, tomographic
calculations are made to obtain the unknown
cross-sectional sound speed c(x,y) of the target
medium knowing the travel time data Tm for themultiple obaservation paths m=1-M. We assumed
that the highy distorted waves, including thosetransmitting through the spinal cord, does notsatisfy the straight ray propagation assumption.
Hence, these diorted waves are excluded from thetomographic calculation.
It is noted that the abdominal sound speed of
the fat region, which is around 1450m/s, is much
lower than the average value of the soft tissues of
1520m/s. On the other hand, the sound speed of
yamada@cc.tuat.ac.jp

T/R

380 mmWith the escalation of the public medical
expenses, importance of the preventive medicalcare of adult deceases was recognized. Under thecircumstances, Japanese government introduced themetabolic syndrome examination as the healthdiagnosis from Apr. 2008. For this purpose, wehave been studying the ultrasound tomographic
reconstruction of the abdominal sound speed image
aiming to measure the visceral fat area1,2. In thispaper, examinations were made to verify thevalidity and precision of the visceral fat area
measurement based on
experiment using aphantom specimen of human abdomen.

380 mm

Fig.1 Transmitter/receiver arrangement
and propagation path.
protein regions including muscle, intestine andkidney, which is above 1550m/s, is much higher
than the average value. The fact enables us toestimate the fat areas from the reconstructed
abdominal cross sectional sound speed image. Here,in order to serve the technique to the metabolic
syndrome diagnosis, visceral fat regions should bediscriminated from the subcutaneous fat region. To
this end, border between the subcutaneous andvisceral region is estimated using the marked points
obtained along the high sound speed abdominal
muscle regions in the reconstructed image. Using
the border information thus obtained, visceral fat
regions are separated from the subcutaneous onesand visceral fat area can be finally measured.
3. Evaluation experiment
3.1 Transducer/receiver arrangement
As shown in Fig.1, a facing pair of ultrasoundtransmitter and receiver (with frequency band
10-500[kHz] and aperture diameter 40[mm]) are
moved along the abdominal peripheral circularboundaries with diameter D =380[mm]. The
transmitter is moved at 32 equiangular points andthe receiver is moved along 16 equiangular pointsalong the circular boundaries. With the combinationof these transmitter and receiver points,
measurements are made along M = 96 paths.
3.2 Phantom

1500

Sound speed, [m/s]

1575

1425

(a)
Fig.2 Sample specimen arrangement usedin experiment
An abdominal mimicking phantom was
prepared as shown in Fig.2,. A urethane wall
ultrasound abdominal phantom (CIRS: Model 57,
275x200 [mm]) having a plastic spinal cord pillar
was used as a container. At the circumference
region, high speed polyethylene glycol objects wereembedded as abdominal muscle regions, where 8%
concentration glycerin was added to adjust thesound speed with c2=1575m/s. In the interior part,food oil objects with sound speed c3=1450 m/s wereembedded as visceral fat regions. Between theobjects, ultrasound gel with sound speed c1=1500m/s was filled.
3.3 Result and discussion
Using the travel time observation data for theabdominal phantom described above, a soundspeed image was reconstructed as shown in
Fig.3(a). In addition to that, the images
using the simulation data were comparedbased on the ideal straight ray propagation
calculation and the rigorous finite difference
methods, as shown in Fig.3(b) and (c),respectively. The experimental result in (a) islittle bit degraded compared to thetheoretical ones in (b) and (c). Especially, thedegradation
of
the
image
in
the
subcutaneous region is evident. This iscaused by the lack of the path data and canbe improved if more number of path dataaround subcutaneous region is incorporated.
Another cause of the degradation is due tothe defects of the phantom specimen such as
the misalignment of the object, or the
mixture of the air bubbles at the object
interface. On the whole, however, it wasdemonstrated that the reproducibility of theimage was almost satisfactory, especially forthe purpose of the visceral fat area
measurement.

(b)

(c)
Fig.3 Reconstructed sound speed image of theabdominal phantom: (a) image using themeasured data, (b) image using the simulated
data based on the straight ray propagation
model, (c) same as in (b) based on the finite
difference calculation. The reconstructedcolored sound speed images are superimposedwith the predetermined gray-scale image.

References
1. A.Yamada, K.Nogami, “Ultrasound travel time
tomography for the sound speed abdominal
imaging”, 2007 Int. Conf. Ultrasonic CD-ROM,
Vienna, Austria, 89 (Apr. 2007).
2. K.Nogami, A.Yamada, “Evaluation experimentof ultrasound CT for the abdominal sound speed
imaging”, Jpn.J.Appl.Phys., 46, 7B,4820-4826(2007).

3P2b-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 371- 372
11-13 November, 2008

直角四方向観測型超音波逆散乱トモグラフィ
Quadrangular View Ultrasound Inverse Scattering
Computed Tomography
山田晃†（農工大院 生物シ応用科）
Akira Yamada (Grad. Bioappl. and Sys. Eng., Tokyo Univ. of A&T)
Ultrasound inverse scattering imaging technique from the quadrangular observation data configured with four linear array probes was
proposed, aiming at a practical and versatile inverse scattering imaging system featuring lower cost and higher-speed data acquisition.
In the present method, backward and sideward scattering wave data as well as the conventional forward scattering data wereincorporated in the reconstruction calculations based on the Fourier slice theorem. From the simulation examinations, validity of themethod was demonstrated, despite the difficulty of the inverse problem due to the limited quadrangular observation view as well as
the finite aperture of the linear arrays.

1. Introduction

2. Principles
Four linear array transducers are arranged
along a square side around the target as shown in
Fig.1. When emitting pulsed plane waves from oneof the linear array, forward, backward, rightward
and leftward scattering waves are observed along
the each square side arrays. We propose an inverse
scattering method using only four sets ofillumination view data which is collected byemitting the waves from each quadrangularyamada@cc.tuat.ac.jp

θT=π/2θT=πyc(x,y)

θΤ=3π/2

Ultrasound inverse scattering computed
tomography is expected to be useful to theapplication for the medical diagnosis andnon-destructive inspection.1 For the realization of
the technique, large-scale ring array data acquisition
systems had ever been developed.2 The method has
difficulties that data collections are required fromgreat number of view directions around the object,
therefore, hardware cost becomes very high, in
addition to that, great number of data observation
prevents the high speed data acquisition. To resolve
the problem, we had proposed a square arraysystem placing four linear arrays at the perimeter of
the target region.3 In this method, wide band
multifrequency scattering components wereincoprporated in the resonctrcuiton procedure, tomake it possible to reconstruct the image by using
few number of view data around the qudrangular
illumination directions. There was, however, a room
for improvements, since only the forward scattering
data were used. In this paper, backward andsideward scattering wave data as well as theconventional forward scattering data areincorporated in the reconstruction calculations. As aresult, it is realized to reconstruct the image only byusing four quardranguar view data.

x

2d

c0

ObjectθT=0Linear Array Probe

Fig.1 Data observation geometry using four
linear arrays along square perimeter of theobject.
direction.
As preprocessing of the received wave, thescattered wave component φ(t) is obtained bysubtracting the incident wave φi(t) from the net
observation wave φnet(t) (φ=φnet-φi), after that
temporal angular frequency components φω isextracted by the Fourier transform of φ. We
consider the problem to obtain the object’s
parameters o(x,y) from the observation φω(x’) along
the array axis x’ at y’=d . Here, o(x,y) is defined withrespect to the sound speed c(x,y) of the medium, andthebackground constant sound speed c0 aso(x,y)=c02/c(x,y)2-1. To this end, φω(x’) is Fouriertransformed with respect to x’ to obtain Φω(Kx’). DataΦω(Kx) is related with the object function according to
the following Fourier diffraction slice theorem under
the weak scattering Born approximation.
Φω ( K x − k0 sinθ , y = d ) e− id k2
0− ( K − k sin θ )
0
x
T

T

i
2

k0

2

O( K x , K y = k

2
0
2

− (K

2

=

2

x

− k0 sinθT ) − k cosθT )k0 − ( K x − k0 sinθT )

0

2

,

(1)

Ky
2k

2k0

|O(Kx, Ky)|

0

Kx

-k0
-2k0
-2k0

-0.5-2k
2k0
0
Kx

0

In order to demonstrate the validity of themethod described above, simulation test
examinations were carried out. As a numericalphantom specimen, cylindrical object with radius
a=6 mm and sound speed variation 0.1% isconsidered at the arbitrary position in the target
region. Four linear array probes: each one is 64 mm
long having 128 elements with 0.5 mm spacing,which is quarter wavelength at the fundamental
frequency 750 kHz. They are placed along thesquare perimeters (64 mm x 64 mm) of the object.
The sets of data for the quadrangular illumination
with different frequency component in the range
lower than f=750 kHz were calculated. They were
mapped over the Fourier plane. Figure 3(a) shows
the gray scale image of the log amplitude ofO(Kx,Ky) in the Fourier plane. On the other hand,

0

k0

-k0

0
(b)

k0

Kx

2k0

Fig.3 Calculated object function: (a) grayscale image of log(|O(Kx,Ky)|) on Fourier
plane and (b) cross sectional profile of|O(Kx,Ky)| on Kx axis (solid line show theresult from the scattered data, dotted line fromthe theory).
x 10-4

y[mm]

10

8

20

6
0

4

-20
-20

0
(a)

20

x [mm][c(x)- c0]/c0

Fig.2 Contour plots of the data in the
Fourier plane with multi-frequency
wave
illuminationfromquadrangular direction.

Simulation Test

-k0

(a)

-2k0

where, k0=ω/c0 is the wave number, θT is thetransmitter direction and O(Kx, Ky) is the twodimensional spatial Fourier transform of the object
o(x,y) with respect to (x, y) .
Equation (1) states that Fourier plane data canbe obtained from the receiver array at y=d over the
locus of the upper half semicircles centered at(k0sinθT, -k0cosθT) and radius k0. It is noted thataperture observation angle θs is less than π/4
because of the square aperture of the receiver arrays.
Consequently, obtainable locus of the data becomes
quarter circles. By changing the temporal angularfrequency over the range 0<ω<ω0, the quartercircular arc data with varying radius (=k0) can beobtained. These quarter circles are drawn for thedifferent observation view, i.e., using the collected
data along y=+d, y=-d, x=+d and x=-d. As a result,
Fourier plane data can be fulfilled within the entire
circle with radius 2k0 as shown in Fig.2. By
executing the inverse Fourier transform of the dataO(Kx, Ky), the object function o(x,y) (i.e., the soundspeed c(x,y)) can finally be obtained.

1

0.5

0

-k0

3.

Obs.
Theory

1.5

2k

-k0

x 10-7

2

k0

k0

-2k0

2.5

Ky

0

8

x 10-4
Obs.
Theory

6
4

2

2

0

0
-20

0
(b)

20
x [mm]

Fig.4 Reconstructed sound speed image of thecylindrical object: (a)gray scale image on (x,y)
plane, (b)cross-sectional image on x-axis.
Results from the scattered data (solid line) arecompared to the theory (dotted line).
Fig.3(b) shows the cross sectional plot of the samedata along Kx axis, where the results (solid line) arecompared with the theory (dotted line). We can seethat the data is in accordance with the theory,
although there are a few part of missing regions inparticular directions. Finally, carrying out inverse
Fourier transform calculation, sound speed imagec(x,y) was reconstructed as shown in Fig.4, where(a) shows the gray scale image on (x,y) plane, and(b) shows the cross sectional plot on x axis. Resultswith solid line are compared with the theory withdotted red line. The reconstructed sound speed
value is slightly lower caused by the missing of thedata in the Fourier plane. Except this, overall
reproducibility of the reconstructed image is fairly
good both in shape and sound speed value.
References
1. A. Yamada and K. Kurahashi: Jpn. J. Appl. Phys.,32, (1993) 2507.
2. M. P. Andre, H. S. Janee, P. J. Martin, G. P. Otto,
B. A. Spivey and D. A. Palmer: Int. J. Imag. Syst.
Tech., 8(1997) 137.
3. A.Yamada and S. Yano: Jpn. J. Appl. Phys., 8A,(2004) 5582.

3P2b-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 373- 374
11-13 November, 2008

Improvement of Vibrational Distribution Measurementof Piezoelectric Devices based on Image Processings
画像処理に基づいた圧電デバイス振動変位分布測定法の改良
Kentaro Tachibana, Yasuaki Watanabe, Noriyuki Imaeda, Shigeyoshi Goka, Takayuki
Sato and Hitoshi Sekimoto (Graduate School of Science and Engineering, Tokyo
Metropolitan University)
橘 健太朗，渡部泰明，今枝憲幸，五箇繁善，佐藤隆幸，関本 仁（首都大院 理工）

1. Introduction

Image Transfer

Measuring the vibration mode shape is very
important when designing piezoelectric devices. We
have developed many methods for visualizing modeshapes that combine surface speckle interferometry
and image-processing techniques for highfrequency resonators[1-4]. The methods all involve
irradiating the surface of a roughly finished device
with a collimated laser beam and capturing imagesof the speckle field generated on the surface with avideo camera.
We reported an improved laser speckle methodthat increases detection sensitivity using
stroboscopic laser irradiation and estimates theabsolute vibration displacement [5-8]. This method
was based on a simple surface-interferometricmodel and statistical operations for the interference
intensity of the speckle images. We applied thismethod to a burst wave device excitation systemusing two lasers with different wavelengths[9].
We explain how we improved upon the above
mentioned laser speckle method and system. The
unique features of this method include 1)
concurrent irradiation of the two-lasers that use apolarization-controlled optical mixer, 2) improved
displacement measuring accuracy and range
achieved through exclusion of the interference
coefficient g from the displacement calculation, and3) linearization of two-dimensional correlation
images to "net" vibrational displacement
distributions,whichenableanabsolute
displacement estimation on the entire surface of thedevices, using the data from partial surfaces
measurements.

2. Measurement system
Figure 1 is a block diagram of themeasurement system with two lasers and burst
wave device excitation. The basic hardware setup
was the same as [9].
bobo@esys.eei.metro-u.ac.jp

MirrorRed

CCD
CameraCoaxialSwitch

PC

LD2

Blue

CaptureTrigger

Lens

Low Frequency
Oscillator

ND Filter

MirrorLaser Diodes
with Collimators

LD1

Modulation
SignalSignal Generator(Pulse Modulation)

SampleBurst Wave

Half
MirrorFig. 1 Experimental setup of full-field in-plane motion visualization
system using burst resonator excitation and two lasers.

In this system a half mirror was placed to mix
the collimated laser beams. To avoid the CCD
saturation and to equalize the detection sensitivity
for each laser, a natural density (ND) optical filter
was used. The azimuth angles of the lasers were
each adjusted to obtain the maximum detection
sensitivity for the in-plane vibrational displacement.
3. Improved displacement measuring accuracy
In the burst-wave excitation system, thedifference in speckle brightness caused by theinterference condition between the resonator-restingand -driving states is approximately given by⎛ sin 2kdx ⎞ .
ΔI = γ ⎜1 −⎟2kdx ⎠⎝(1)

sin 2 kdx
= α dx 3 + β dx 2 + ηdx + 1 ,
2 kdx

(2)

Here, k = 2π/λ, where λ is the wavelength ofthe laser diode, γ is the interference factor of thefringes, and dx is the vibrational displacement of
the resonator. In this equation, we assume that dx
changes linearly.
In the proposed method, γ is
not required to calculate the vibrational
displacement.
To improve the order of approximation, we
introduced the third order polynomial function toapproximate the 2nd term in the parentheses in (1).

where α, β, and η are constants and can be derived
by determining λ and the approximation range ofthe vibrational displacement. By rearranging (1)and (2), the differences in optical intensities ΔIs fortwo lasers can be obtained. We can thus obtain theabsolute vibrational displacement using thefollowing equation,

where

180

(3)

⎧ A = p Δ I 1α 2 − Δ I 2α 1⎪
⎨ B = pΔI1β 2 − ΔI 2 β1
⎪C = p Δ I η − Δ I η
1 2
2 1 ,
⎩

Measured displacement [nm]− B + B 2 − 4 ACdx =2Ais clear from the figures that the proposed imagetransformation method gives the linear mode shapefrom the 2D correlation image.
160
140
120
100
80
60
40
20
0
0

and p = λ1 / λ2 .

20

40

60

80

100

120

140

160

180

Absolute displacement [nm]Fig. 2 Experimental results of displacement measurement.

4.

Transformation of images

In our previous method, we found areas withapproximately the same vibrational amplitude in
test resonators from the two-dimensionalcorrelation images over the entire surface of theresonators, and then we estimated the vibrational
displacement in each marked area [8,9].
We propose a new vibrational distribution
estimation algorithm for deriving whole vibrational
displacement over the entire surface of theresonator using partial displacement measurement
and two-step transformations of the twodimensional correlation images.
1) The differential interference intensity forresonator- resting and resonator-driving states isgiven by the inverse transformation of thecorrelation equation based on the probability theory.
2) The vibrational amplitude is obtained bysubstituting the above differential interference
intensity into the inverse function of (1).
4. Experimental results
On the basis of our method, we estimated themeasured absolute vibrational amplitude [7]. Fivehundred image pairs were accumulated andaveraged to reduce the CCD and environmental
noises.
Figure 2 shows the measured in-plane
displacement vs. the absolute displacement. The
dotted line represents the ideal characteristics. It isclear from Fig. 2 that the measurement error of +25
nm was observed at 60 to 100 nm. However, theminimum measurable value was expanded to 20 nm
compared to 50 nm reported in the previous paper[9].
This improvement is a consequence ofapplying higher order polynomial expression to theinterference relation. The maximum measurable
value of 160 nm is limited by the wavelength of theviolet laser
Figures 3(a) and (b) show the experimental
results of full-field in-plane motion of fundamental
TS-mode in a 16 MHz quartz crystal resonator. It(a) 2D correlation(b) Transformed image

Fig. 3 Experimental results of in-plane motion of quartz resonator.

5. Conclusions
We have improved the mode shapevisualization method, which is based on a novel
two-dimensional
image
transform;
andsimultaneous device irradiation with two lasers withdifferent wavelengths.
Acknowledgment
This work was partially supported by
Grant-in-Aid for Scientific Research (C), No.
20560399, MEXT, Japan.
References
1. Y. Watanabe, Y. Shikama, S. Goka, T. Sato and H. Sekimoto: Jpn. J. Appl. Phys.
40 (2001) 3572.
2. Y. Watanabe, T. Tominaga, T. Sato, S. Goka and H. Sekimoto: Jpn. J. Appl.
Phys. 41 (2002) 3313.
3. Y. Watanabe, T. Sato, S. Goka and H. Sekimoto: Proc. IEEE Ultrasonic Symp.,
2002, pp. 928.
4. Y. Watanabe, S. Goka, T. Sato and H. Sekimoto: IEEE Trans. Ultrason.
Ferroelectr. and Freq. Control 51 (2004) 491.
5. Y. Watanabe, K. Tsuno, T. Tsuda, S. Goka, T. Sato and H. Sekimoto: Proc. 2004
Annu. Symp. Freq. Control, 2004, pp. 591.
6. Y. Watanabe, K. Tsuno, T. Tsuda, S. Goka and H. Sekimoto: Jpn. J. Appl. Phys.
44 (2005) 4440.
7. Y. Watanabe, T. Tsuda, S. Ishii, S. Goka and H. Sekimoto: Jpn. J. Appl. Phys.
45 (2006) 4585.
8. Y. Watanabe, S. Ishii, S. Goka, H. Sekimoto, M. Kato and T. Tsuda: Proc. 2006
Annu. Symp. Freq. Control, 2006, pp.554
9. Y. Watanabe, N. Imaeda, S. Ishii, S. Goka, T. Sato and H. Sekimoto: Proc. 2007
Annu. Symp. Freq. Control, 2007, pp.160-163.
10. Y. Watanabe, H. Kitabori, S. Goka, T. Sato and H. Sekimoto: Trans on IEICE,
J86-C (2003) 1337.
11. Y. Watanabe, T. Sato, S. Goka and H. Sekimoto: Acoust. Sci. & Tech. 23(2002) 284.

3P2b-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 375- 376
11-13 November, 2008

Visualization of elastic waves by photorefractive
imaging method
フォトリフラクティブ映像法による弾性波の可視化
Takahiro Miura1†, Makoto Ochiai1, Yoshikazu Ohara2 and Kazushi Yamanaka2(1 Power Systems Company, Toshiba Corp.; 2Tohoku Univ.)†

三浦崇広1 ，落合誠1，小原良和2，山中一司2 （1東芝

1. Introduction
Recently, nondestructive testing (NDT) is
increasingly important because of social demand
for structural reliability, manufacturing-quality
assurance, etc. Ultrasoinc testing (UT) is commonly
adapted to NDT, but it is difficult to reduce theinspection time due to contact of transducers andlimitatedinspection
area.
The
real-time
photoractive (PR) imaging [1] of 2D ultrasonicwaves has a potential of reliable and high-speed
inspection, though it has not been applied todiffraction and scattering at defects.
The authors improved the PR imaging by thephase difference (PD) method[2]. In this work weapply it to diffraction analysis of travelling waves ata slit with high signal to noise ratio (S/N).
2. Principle of PD method
The phase of a signal optical beam IS reflectedor scattered from a vibrating object is given asδ s = δ 1 sin (ω s t + ϕ s ) = 4πξ λ sin (ω s t + ϕ s )where ξ , ω s , ϕ s , λ are the vibration amplitude,
angler frequency, the phase and the optical
wavelength, respectively. The phase of thereference
beam
IR
is
modulatedasδ R = δ 2 sin (ω R t + ϕ R ) , by using an electro-optic

電力システム社; 2東北大 工）

the angle between the signal and reference light, Γis the two-wave mixing coefficient, M is thevisibility of the interference fringe, J n is theBessel function of the first kind, Ψ = tan −1 (Ωτ ) ,Ω = ω S − ω R is the frequency difference and τ
is the photorefractive response time. It is important
to note that Eq (1) gives higher sensitivity than inconventional PR method, since the background IB isremoved by subtraction in the right hand side.
B

3. Experimental setup
Figure.1 shows an experimental setup. The
laser beam was divided into two beams with thepolarized beam splitter (PBS). One beam irradiatedthe PRC, whose phase is modulated by the EOM, as
the reference beam. The other beam irradiated thespecimen, and the signal beam reflected or scatteredfrom the specimen irradiated the PRC after imagetransfer by 2 camera lenses.
Photorefractive Crystal(Bi12SiO20)

polarizer
ultrasonicexciterpolarizer

Camera lensCamera lens

IS

CCD

IR
specimenmirrorpolarizer

lens

EO

modulator (EOM), where δ 2 is the modulation

amplitude, ω R is the angler frequency and ϕ R is
the phase. The signal and reference beams form adiffraction grating in the PR crystal. The reference
beam is diffracted to form an image, but a small
fraction of the signal beam is also transmitted as a
background IB which degrade the S/N of images.
However, the intensity of image in the PD method
is [2],
Δ I = I (ϕ R+ ) − I (ϕ R+ + π )2(1)= 8 I R e − α L cos θ (Γ L 2 ) × M 2 J 0 (δ 1 )J 1 (δ 1 )

λ/2
PBS
λ/2
λ/2

B

J 0 (δ 2 )J 1 (δ 2 )cos (Ψ − ϕ s + ϕ + )where α is the optical absorption coefficient, L
is the thickness of the diffraction grating, 2θ istakahiro.miura@toshiba.co.jp

LASER (CW: 532nm)
mirrorFig. 1 Experimental setup

The imaging area was φ30-40mm. The signal andreference beams interfered each other in the PRC toform a diffraction grating, and therefore thereference beam was diffracted by the grating andacquired as an interference image by a CCD camera
For large area inspection, it is important todetect traveling waves propagating to wide arearather than standing waves confined withinboundaries. In this study, we use a copy paper
0.1mm in thick as a tentative specimen. The CCD
camera image of specimen surface is shown in Fig.
2. The paper had a slit (tear) with 12mm length
shown in the lower right part of the image.
Ultrasonic wave was excited at the center of theimage by a piezoelectric transducer. The excitation
frequency was 48kHz and the reference beamfrequency was modulated to 47.999kHz, andtherefore the difference frequency Ω=1Hz. Induced
ultrasonic amplitude measured by heterodyne
interferometer was about ±12nm.

transducer. The traveling wave reached the slit, andchanged its direction due to diffraction at the slit.
Figure 4 shows magnified image at the slit. In
the PD method image (Fig.4(a)), it is clear that thephase of the traveling waves was changed at the slit
as indicated between the allows. For sensitivity
improvement, we averaged the PD method image
for 10 cycles as shown in Fig.4(b). It is clearer
because high spatial frequency noises were
removed by the averaging.

(a)
10mm

Image of paper surface

Total laser power was 0.8W, the signal beam
power was 22μW and the reference beam power
was 2.1mW at the front of BSO crystal. The
integration time of the CCD camera was 100ms.
3. Result

Figure 3 shows PD images of traveling waves
on the paper, which it was electrically driven withdifferent phase of the reference beam modulation.

Figure 5 shows an amplitude profile along thedotted line in Fig. 3 (315°) through the center ofconcentric traveling wave (350 pixel), and the slit
position (450 pixel). At the position of slit (450pixel), the traveling wave was disappeared, in
contrast to at the position of 250 pixel where there
was no slit.

Amplitude

Fig. 2(b)

Fig. 4 Magnified image at the slit. (a) PD method
image. (b) Averaged PD method image for 10 cycles.

100 150 200 250 300 350 400 450 500 550 600

Pixel

Fig. 5 Amplitude profile of traveling waves

4. Conclusion
We applied the PD method, including thatusing an improved signal analysis, to imaging ofdiffraction behavior of traveling ultrasonic waves
on a paper, and observed clear phase change at a slit.
We will apply this technique to inspection of metal
structures in the future.

Fig. 3

Traveling waves on the paper

It is clear that traveling waves were generated
concentrically on the paper by piezoelectric

References
1. K. L. Telschow, V. A. Deason: Ultrasonics
40(2002)1025-1035.
2. K. Yamanaka, K. Aizu, S. Sakai, A. Mizukami
and H. Cho: Key Engineering Materials. 261-263(2004) 969-974.

3P2b-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 377- 378
11-13 November, 2008

Imaging of surface acoustic wave reflection and focusing
using circular, ellipsoidal and parabolic boundaries
円、楕円、放物線境界での表面音響波の反射や収束のイメージ
ング
Motonobu Tomoda 1†, Oliver B. Wright 1, Kosei Ueno 2, Yoshiaki Nishijima 2, Saulius
Juodkazis 2, and Hiroaki Misawa 2 (1 Graduate School of Engineering, Hokkaido
University; 2 Research Institute for Electronic Science, Hokkaido University)
友田基信 1†，Oliver B. Wright 1，上野貢生 2，西島喜明 2，Saulius Juodkazis 2，三澤弘明 2（1 北海道
大学大学院工学研究科; 2 北海道大学電子科学研究所）

1. Introduction
Gigahertz surface acoustic waves (SAW) are
now in common use in filters inside cellular phones.
SAW’s are also put to use for the nondestructive
testing of the thickness or elastic properties of thinfilms. SAW’s can be confined on the surface of a
substrate in resonator configurations often making
use of interdigital electrode technology.[1] The best
way to investigate fundamental SAW behavior insuch confined geometries is by imaging the acoustic
wave field. Real time imaging brings the additional
advantage of allowing the evolution of the wave
field to be studied in two dimensions.
By exploiting a nondestructive and noncontact
opticalSAW
excitation
andimagingtechnique,[2-4] we investigate the real time
propagation of SAW in confined or partiallyconfined geometries. In particular we image thereflection and focusing of gigahertz SAW’s using
microscale circular, ellipsoidal and parabolic
boundaries in a crystalline silicon substrate.

up to ~1 GHz, with a typical SAW pulse duration~1 ns. The optical probe beam passes through a
optical delay line and then into the Sagnac
interferometer.[4] The probe spot position can bescanned in two dimensions over the sample surface
by controlling a two-axis rotating mirror. After eachpump optical pulse, two probe pulses are reflectedfrom the sample and pass back into theinterferometer for measurement of their phasedifference, approximately proportional to theoutward velocity of the sample surface.
Synchronous detection of the interferometer output
from a photodetector is achieved with a lock-in
amplifier referenced to the pump chopping
frequency. The typical surface displacements
measured are ~10 pm. It takes approximately 5
minutes to obtain a 100 μm×100 μm raster scan

2. Imaging system
Fig. 1 shows a schematic diagram of theimaging system. The method is based on the opticalpump and probe technique, making use of a Sagnac
interferometer and an optical scanning system.[4]We make use of a mode-locked Ti:Sapphire
femtosecond laser system that delivers ~100 fs
duration infrared optical pulses at a repetition rateof 80.4 MHz (one pulse every 12.4 ns). We operatewith pump and probe pulses at wavelengths of 415
nm and 830 nm, respectively. An acousto-optic
modulator (AOM) is used to chop the optical pumpbeam at 1 MHz. The pump pulse energy ~ 0.1 nJ,
selected at about half the damage threshold, isfocused to a ~2 μm diameter spot on the sample
surface using a (50) microscope objective lens.
This pump pulse generates SAW’s at frequencies--------------------------------------------------------------e-mail address: mtomoda@eng.hokudai.ac.jp

Fig. 1. Schematic diagram of the imaging system. SHG:
secondharmonic
generation
crystal,AOM:
acousto-optical modulator, pol.: polarizer, NPBS:
non-polarizing beam splitter, PBS: polarizing beam
splitter, λ/4: quarter-wave retarder, and λ/2: half-wave
retarder.

image with a 1 μm step. Animations up to 12.4 ns
can be obtained by varying the delay time between
the pump and the probe pulses.
3. Samples
Micro-fabrication
methods
includinglithography and dry etching are used to make thesamples. The samples are fabricated on a silicon(100) wafer by plasma dry etching using a SF6 andC4F8 gas mixture. The use of two gases ensured
etching of structures with vertical side walls. The
etching was carried out in a sequence of etching(SF6) and passivation (C4F8) steps in alternation.
The overall etching rate was ~1 μm min-1, ensuring
speedy preparation. Grooves of depth and width~10 μm are formed in the shape of circles,
ellipsoids and parabolas. The sample is then coatedwith a polycrystalline chromium film of thickness~40 nm by rf sputtering to enhance the opticalpump pulse absorption and probe pulse reflection.
Optical reflectivity images of the circular andparabolic boundaries are shown in Fig. 2 (a) and(c).
4. Results and discussion
SAW propagation images for these samples
were obtained as animations with 30 frames over
12.4 ns. We show in Figs. 2 (b) and (d) typical
SAW images for circular and parabolic shapeboundaries.
The silicon (100) surface shows fourfold
rotational symmetry in its linear elastic properties.
SAW’s propagating along [010] (and in equivalent
symmetry directions) are Rayleigh-like modes.[5]SAW’s propagating along [011] (and in equivalent
symmetry directions) are pseudo-SAW modes.[5]Due to the very thin Cr film, our measured
propagation velocities ~5 km s-1 are very close to
the values for bulk Si.[6] The slight difference in
SAW and PSAW velocities produces slightdeviations from circular wave fronts, as is evident
at 6.2 ns in Fig. 2 (b).
In Fig. 2 (b), corresponding to a circularresonator, the anisotropy of the substrate causes thereflected SAW wave front at 18.6 ns to be squareshaped, after which time the waves focus to a point
in a symmetrical position with respect to the opticalpump spot (the black spot in the figure). In Fig. 2(d) corresponding to a parabolic boundary, theSAW pulses are excited near the focus. The
reflected wave fronts are approximately straight.
We also have made animations of SAW’s insideelliptical boundaries, and have observed that SAW’s
excited near one focus converge to the second focus.
We are at present investigating precisely how the Si

Fig. 2. (a) Optical reflectivity image of a circularresonator of internal diameter 100 μm. (c) Opticalreflectivity image of a sample with a parabolic
boundary. The substrate is a Si (001) covered with a 40
nm polycrystalline Cr film. (b), (d) snapshots of the
SAW propagation corresponding to the samples of (a)and (c), respectively. The times after pumping areindicated by the arrows.

anisotropy affects the evolution of the wave front
shapes on reflection.
5. Conclusions
In conclusion we have observed SAW reflection
and focusing using microscale circular, ellipsoidal
and parabolic boundaries in a crystalline silicon
substrate. Further work of interest involves
increasing the optical excitation energy in order toproduce nonlinear acoustic resonances in
microscale cavities. Imaging the waves in real timeshould allow novel effects to be categorized, suchas shock waves or instabilities.
References
1. R. Weigel et al.: IEEE Trans. Micro. Theory
Tech. 50 (2002) 738.
2. Y. Sugawara et al.: Phys. Rev. Lett. 88 (2002)
185504.
3. O. B. Wright, O. Matsuda and Y. Sugawara: Jpn.
J. Appl. Phys. 44 (2005) 4292.
4. T. Tachizaki et al.: Rev, Sci. Inst. 77 (2006)
043713.
5. R. E. Vines, M. R. Hauser and J. P. Wolfe: Z.
Phys. B 98 (1995) 255.
6. H. Coufal et al.: J. Acoust. Soc. Am. 95 (1994)1158.

3P2b-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 379- 380
11-13 November, 2008

Real-time imaging of GHz acoustic waves
on bulk acoustic resonators
バルク音響振動子における GHz 音響波伝搬の実時間イメージング
Takashi Fujikura1‡, Osamu Matsuda1, Oliver B. Wright1, Jeremy Masson2 and Sylvain
Ballandras2(1 Grad. Sch. Eng., Hokkaido Univ., Sapporo, Japan; 2 FEMTO-ST, Besancon, France)22
藤倉崇 1‡，松田理 1，Oliver B. Wright1, Jeremy Masson , Sylvain Ballandras
1
2( 北海道大 工; FEMTO-ST, Besancon, France)
1. Introduction
Acoustic devices are indispensible for wirelesscommunication systems. In particular, surface
acoustic wave (SAW) devices are widely applied in
the telecommunications industry. Film bulk acoustic
resonators (FBAR) are under development becauseof their compact construction1. For high frequency
operation up to several GHz, FBAR’s make use of
the thickness resonance of thin piezoelectric films.
To evaluate such filters, electrical measurement andmathematical simulation are useful tools. Another
tool is the imaging of surface vibration, allowing
the vibrational modes to be directly accessed.
Both optical and local probe methods forimaging bulk acoustic resonances and SAW on
FBAR’s have been reported2-5. These studies areuseful for understanding the device acoustics andreveal leakage of acoustic waves from the device.
Such measurements have been carried out in thefrequency domain, and the frequency range has
been limited to relatively narrow bands for each
investigation.
Here we propose a wideband time-resolved
technique to increase the frequency range of themeasurements on FBAR devices, based on an
ultrafast optical imaging technique combined withelectric excitation. The electrical excitation is
synchronized with the ultrashort probe laser pulses.
Acoustic waves over a broad frequency range (100MHz-2.5 GHz) are excited and imaged. By the useof Fourier transforms, we extract the acoustic wave
amplitude at each frequency and the acoustic
dispersion relation.
2. Experimental setup
The experimental setup is shown in Fig. 1. We
use an optical pump and probe technique and acommon-path interferometer6. The FBAR, shown in
Fig. 2, consists of a thin film of AlN of thickness 2
m, and is coated with a Pt electrode7. The
fundamental resonance frequency is 120 MHz, withresonances up to the GHz range.
We use a mode-locked Ti:Sapphire laser ofFig. 1 Experimental setup

Fig. 2 Optical micrograph of the FBAR
central wavelength 830 nm, pulse duration ~200 fs,
and repetition rate 76 MHz. The laser beam isdivided into two, one for the probe light andanother for use in a high bandwidth (~3 GHz)
photodetector. The photodetector output is fed to a
wideband amplifier whose output is connected to
the FBAR device. The electrical pulses driving the
FBAR are thus synchronized to the probe opticalpulses. The excitation optical beam before thephotodetector is modulated at 1 MHz for purposesof synchronous detection using a lock-in amplifier
at this frequency. The probe light beam passes
through a variable (up to 4 m) delay line. Sets of
two probe pulses separated by a time interval of 100
ps are focused to a ~2 m spot on the sample with a
50 objective lens, and are raster scanned over its
surface. The reflected probe pulses enter acommon-path interferometer where they are
combined for detection of optical phase variations
that are directly proportional to the normal velocityof the sample surface. The displacements of thesample surface are resolved to ~1 pm resolution.
The typical image size is 220 m 220 m, with anacquisition time of 20 min. To form an animation
we measure 60 images over the ~13 ns interval
between optical (or electrical) pulses.
3. Experimental results
We have obtained images over the frequency
range 100 MHz-2.5 GHz. Typical results in the time
domain are shown in Fig. 3.

Fig. 3 Experimental time-resolved surface vibration
images for a 220 m 220 m region of the FBAR.
(a) and (b) correspond to a time difference of 6790
ps.
The mode patterns seen correspond to a
combination of surface acoustic and bulk acoustic
waves. The temporal Fourier transfoms (not shown)
are used to obtain the mode patterns at frequency
intervals of 76 MHz. In addition to the bulk
thickness resonances periodic in the fundamental
resonance frequency, we also observe SAW
resonances and SAW leakage from the device(though not very clear in Fig. 3 outside the regionof the FBAR due to the poor contrast).
4. Conclusions
We have demonstrated the real-time imagingof electrically-excited acoustic waves over a wide
frequency range in bulk acoustic resonators bymeans of an ultrafast optical technique. Thisimaging system should prove useful for theevaluation of acoustic devices which operate in the
GHz region .
Acknowledgment
We are grateful to P. Muralt for the fabricationof the FBAR samples.
References
1. R. Weigel, D. P. Morgan, J. M. Owens, A.
Ballato, K. M. lakin, K. Hashimoto, and C. C. W.
Ruppel: IEEE Trans. Micro. Theory Tech. 50(2002) 738.
2. J. V. Knuuttila, P. T. Tikka, and M. M. Salomaa:
Opt. Lett. 25 (2000) 613.
3. K. Kokkonen and M. Kaivola: Appl. Phys. Lett.
92 (2008) 063502.
4. J. E. Graebner, B. P. Barber, P. L. Gammel, and
D. S. Greywall: Appl. Phys. Lett. 78 (2001) 161.
5. H. Safar, R. N. Kleiman, B. P. Barber, P. L.
Gammel, J. Pastalan, H. Huggins, L. Fetter, and
R. Miller: Appl. Phys. Lett. 77 (2000) 136.
6. T. Tachizaki, T. Muroya, and O. Matsuda: Rev.
Sci. Instrum. 77 (2006) 043713.
7. J. Masson, G. Martin, R. Boudot, Y. Gruson, S.
Ballandras, A. Artieda, P. Muralt, B. Belgacem,and L. Chomeloux: Proc. IEEE Frequency
Control Symposium, (2007) p.741.

3P2b-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 381- 382
11-13 November, 2008

Real time imaging and dispersion behaviorof Lamb waves in an elastic wedge
くさび構造におけるラム波伝播の実時間イメージングと分散解析
Shinnosuke Matsueda†, Motonobu Tomoda, Osamu Matsuda and Oliver B. Wright(Graduate School of Engineering, Hokkaido University)†

松枝真之介 ，友田基信，松田理，Oliver B. Wright （北海道大学大学院工学研究科）

1. Introduction
Flexural acoustic waves in plates, namely
Lamb waves, show dispersion depending on
the plate thickness.[1] They can be used for thenondestructive testing of plates or pipes, forexample. Lamb waves are also expected inplates of non-uniform thickness, in which casetheir propagation becomes much more
complex.[2] In particular, in a quadratic wedge
the propagation time diverges as a wave packet
approaches the sharp end at normal incidence,
producing the so-called „acoustic black hole‟effect in which the wave is not reflected, atleast in theory for a perfect wedge.
In order to elucidate this phenomenon
more clearly, we implement a real time surface
acoustic wave imaging technique at frequencies
up to ~1 GHz with ~1 m lateral and ~1 ps
temporal resolution.[3-5] This nondestructive
and noncontact method is based on the opticalpump and probe technique that makes use ofultrashort laser pulses and interferometricdetection of surface displacement. From thespatiotemporal Fourier transforms of our data
we can also derive the acoustic dispersion
relation and images of the acoustic propagation
at individual frequencies.[6]Fig. 1 Schematic diagram of a gold wedge on asilicon nitride membrane.

3. Imaging method
Fig. 2 shows the measurement setup. We
use a mode-locked Ti:sapphire laser ofrepetition rate 80.4 MHz (one pulse every 12.4ns), a pulse width of 200 fs and a centre
wavelength of 830 nm. The 830 nm beam isused for probing and a second harmonic (415nm) beam is used for pumping. The pump
optical pulses are focused on to the sample to a
~2 μm circular spot or to a line of width ~2 μm
through a 50 microscope objective. This
excites Lamb wave pulses at frequencies up to~1 GHz. Delayed probe light pulses arefocused to a ~1 μm spot through the same
objective lens. Changes in surface displacement
are measured in a Sagnac interferometer by

2. Samples
Gold wedges of various shapes areprepared by rf sputtering, making use of aprogrammable shutter on a translation stage
inside the vacuum chamber. The substrate is acommercial silicon nitride membrane with athickness of 2 μm (as shown in Fig. 1). The
thickness of the gold wedge typically changes
from 6 μm to zero over a length of ~200 μm in
quadratic fashion.
-----------------------------------------------------------e- mail address: matsueda@eng.hokudai.ac.jp

Fig. 2 Measurement setup
DM: dichroic mirror

monitoring the difference in phase between twoprobe light pulses as a function of the delay
time between the pump and probe pulses.[5]The probe light spot is scanned in two
dimensions over the sample surface using a
two-axis rotating mirror. It takes 20 minutes toobtain a 200 μm × 200 μm raster scan image
with a 1 μm step. In this way animations of theLamb wave propagation can be viewed over the~12.4 ns interval between pump pulses.

4. Results and discussion
We have detected Lamb waves in our
structures propagating in all directions on thesample surface. We show in Fig. 3 a typicalLamb wave image for the gold wedge sample.
We observe both fast and a slow Lamb waves.
These are analogous to the symmetric andantisymmetric modes in a single-component
plate.[1] By taking the Fourier transform wewere able to derive the dispersion relations ofboth modes. These dispersion relations were
found to depend on the imaged region on thewedges.

Fig. 3 Snapshot of Lamb waves on a gold
wedge on a silicon nitride membrane. The left
hand quarter of the image corresponds to thebare membrane. The gold wedge becomes
gradually thicker towards the right (see Fig. 1).

References
1. B. A. Auld: “Acoustic Fields and Waves in
Solids”, Vol. II, Wiley, New York (1973)
2. V. V. Krylov and R. E. T. B. Winward: J.
Sound Vib. 200 (2007) 43
3. Y. Sugawara, O. B. Wright, O. Matsuda, M.
Takigahira, Y. Tanaka, S. Tamura and V. E.
Gusev: Phys. Rev. Lett. 88 (2002) 185504
4. O. B. Wright, O. Matsuda and Y. Sugawara:
Jpn. J. Appl. Phys. 44 (2005) 4292
5. T. Tachizaki, T. Muroya, O. Matsuda, Y.
Sugawara, D. H. Hurley and O. B. Wright:
Rev. Sci. Instrum. 77 (2006) 043713
6. Y. Sugawara, O. B. Wright and O. Matsuda:Appl. Phys. Lett. 83 (2003) 1340

3P2b-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 383- 384
11-13 November, 2008

Temperature Distribution Measurement in RectangularSpace by Acoustic Computerized Tomography Using
Projection Data of Unequal Angular Intervals
不等角間隔投影データを用いた音響トモグラフィ法による矩形空間内部温度分布計測
Ayumu Minamide‡, Koichi Mizutani, and Naoto Wakatsuki (Univ. Tsukuba)
南出歩‡，水谷孝一，若槻尚斗 (筑波大院・シス情工)

1. Introduction

minamide@aclab.esys.tsukuba.ac.jp

c0
rc(x,y)xPath------------------------------------------------------------

y

Sound

Temperature distribution measurement is very
important in various fields, such as, for temperature
control in greenhouse1, comfort in office2. Thus,
suiable measurement methods are required, andinvestigated. Among these, acoustic computerized
tomography (A-CT) method3,4 is applied to measuretemperature distribution. This method is based on
Radon transform. Measuring times of flights(TOFs) of acoustic waves between acoustic
transducers, reciprocal of sound velocity
distribution is reconstructed by the A-CT method.
The A-CT method has several advantages, forexample, noncontact measurement, effective use of
the space, large-scale space measurement.
However not to do linear scanning andlotational scaninng, the transducers are hitherto
located at equal intervals along circumference ofmeasurement space, and pseudo linear scanning andlotational scanning whose angular intervals areequal are easily done. However, many applications
are in rectangular spaces. It is inefficient to takecircular arrangements of the transducers in therectangular spaces. Since outside of the circularspace could not be measured and the advantage ofthe effective use of the space is lost. Thus, we try tolocate the acoustic transducers along the sides of
the rectangular space. This causes a problem thatprojection data could not be obtained at equal
angular intervals. Because inverse Radon transform
is integral of direction of angle, projection data of
unequal angular intervals could not be simply used
for summation instead of the integration. In thispaper, we propose new A-CT method to use
projection data of unequal angular intervals. In thismethod, the projection data of unequal angularintervals in r-θ space are interpolated in
two-dimension, so that the data of equal intervals
are obtained. By numerical simulation, we confirm
the usefulness of the proposing method.

s

Acoustic Transducer

R0-R

Fig. 1 Principle of A-CT in rectangular space.
2. Principle
Figure 1 depicts principle of A-CT method inrectangular space. 24 acoustic transducers are located at equal intervals along the sides of the rectangular space. Ordinary A-CT method obtains
dense projection data by interpolating TOFs of parallel sound paths at r-axis. To use all sound paths
and solve the problem of unequal angular intervals,
projection data are mapped to r-θ surface, and interpolated at the r-θ surface. By thetwo-dimensional interpolation, all sound paths areused for reconstruction and projection data of equal
angular intervals are obtained. In this paper, biharmonic spline interpolation method5 is employed.
This method is often used to illustrate contour line
map from scattered data by artificial satellites. The
proposed A-CT method makes a smooth curved
surface from various points. Thus, biharmonic
spline interpolation method is to be effective.

Fig. 2 Exact and reconstructed temperature distributions. (a) Exact distribution. (b) Reconstructed from projection data of 45 ° equal angular intervals. (c) Reconstructed by the proposed method.

Fig. 3 Exact, acquired, and interpolated projection data at r-θ surface. (a) Exact projection data. (b) .Original
projection data. (c) Interpolated projection data.
3. Numerical Simulation

By the numerical simulation, we confirm theusefulness of the proposed method. Figure 2
presents exact and reconstructed temperature distributions. Figure 2(a) presents exact temperature
distribution in rectangular space. The size of therectangular space is 8.0 × 4.0 (m2). The temperature
distribution is given by two Gaussian functions, andbase temperature is 15.0 °C. One Gaussian whose
1/e width is 1.4 m and peak value is 18.0 °C, is located at (2.0 m, 0.0 m). The other is located at (-2.0m, 0.0 m) and 1/e width is 1.8 m. The peak value is13.0 °C. Figure 2(b) is the distribution reconstructed by ordinary A-CT method using 45 ° equal
angular intervals. RMS error of the reconstructed
distribution is about 0.32 °C. Peak values are about
13.73 °C at (-1.9 m, 0.1 m) and about 16.59 °C at(2.0 m, -0.1 m). Figure 2(c) is the distribution reconstructed by the proposed method. 180 projection
data are used for reconstruction. The RMS error isabout 0.09 °C. Peak values are about 13.21 °C at(-2.0 m, 0.0 m), and about 17.37 °C at (2.0 m, 0.0m). Figure 3 presents exact, acquired, and interpolated projection data at r-θ surface, respectively. By
biharmonic spline interpolation, a smooth curved
surface is obtained from Fig. 3(b), as shown in Fig.
3(c).
Since Fig. 2(b) is reconstructed from only 4
projection data, large artifacts accrue. In contrast,
Fig. 2(c) is reconstructed from 180 projection data,
and the artifacts decrease. Moreover, peak values

approach to those of the exact distribution, andRMS error decreases.
4. Conclusion
By the numerical simulation, we confirmed
the usefulness of the proposed method. Interpolating projection data of unequal angular intervals at
r-θ surface, the proposed method could use all projection data. Therefore, peaks of the reconstructed
distribution approach to those of the exact distribution, and RMS error decreases. As future work, experimental verification will be scheduled.
Acknowledgment
This work was supported in part by a Grant-in-Aid
for Scientific Research (B) (No. 17380149) fromthe Japan Society for the Promotion of Science.
References
1. Georgios K. Spanomitsios: J. agric. Engng Res.
80 (2001) 251.
2. Sami Karjalainen, and Olavi Koistinen: Building
and Environment, 43 (2007) 2880.
3. G. Höfelmann, H. O. Luck and P. Becker: J.
Aerosol. Sci. 23 (1992) 51.
4. A. Minamide, K. Mizutani, and N. Wakatsuki:
Jpn. J. Appl. Phys. 47 (2008) 3967.
5. Sandwell, David T: Geophysical Research Letters,Vol. 14, No. 2, (1987) 139.

3P2c-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 385- 386
11-13 November, 2008

Piezoelectric oscillator sensor to detect damages
in a structure
Hyeoksang Kwon‡, Byungsoo Kim and Yongrae(Kyungpook National University, Korea)

2. Finite element analysis
Influence of the damages on a simple
structure was analyzed by the finite element methodwith a commercial software package, ANSYS. The
FEA model contained a small PZT patch attached
to an aluminum plate as the SHM sensor. The
sensor in this work utilized a lateral vibration modeof the PZT patch. Damage to the plate leads to thechange of the electromechanical impedance of theplate, which in turn results in corresponding changeof the resonant frequency of the PZT patch. Henceobservation of the resonant frequency can identify
the crack geometry. Through the FEA, the changeof the lateral mode resonant frequency of the PZTpatch was investigated in relation to the number ofcracks of a certain length and then similar analysis
was performed in relation to the length of cracks
assuming a single crack was present on the plate.
-----------------------------------------------------------‡

hyeoksang.kwon@gmail.com

126000125000

Delta Frequency [Hz]Recent research activities on structural healthmonitoring (SHM) led to the development of smart
sensors and integrated sensing systems in the fieldsof mechanical, aeronautical and civil engineering[1]. Low-cost smart sensors are key ingredients forwide adoption of the structural health monitoring
technology. In particular, the electro-mechanical
impedance based technique, which uses smart
piezoelectric ceramic (PZT) materials, has emerged
as a powerful technique for SHM [2]. This paper
presents the feasibility of a piezoelectric oscillator
sensor to detect the damages in structures for the
SHM purpose. The oscillator sensor is composed ofan electronic feedback oscillator circuit and apiezoelectric vibrator to be attached to a structure ofinterest. Damage to the structure causes a change ofthe impedance spectrum of the structure, which
results in a corresponding change of the resonant
frequency of the PZT patch [3]. The oscillator
sensor can instantly detect the frequency change ina very simple manner. Feasibility of thepiezoelectric oscillator sensor is verified with asample aluminum plate where artificial cracks ofdifferent depth are imposed in sequence. Validity ofthe measurement is confirmed through comparing
the experimental data with the results of finite
element analysis (FEA) of the plate.

According to the results in Fig. 1, the resonant
frequency of the PZT patch decreased in proportion
to both the length and the number of cracks. After acertain threshold length, the resonant frequency
showed almost linear decrease in proportion to thecrack length. For a short crack, increase of the crack
number did not have much influence on theresonant frequency of the PZT sensor. However, fora relatively longer crack, the number of cracks had
significant influence on the resonant frequency.

124000123000122000121000120000119000
d=1

d=2

d=3

d=4

d=5

d=6

d=7

N=9

N=11

Length of cracks(a)125600125400Frequency [Hz]1. Introduction

125200125000124800124600124400124200124000
N=1

N=3

N=5

N=7

Number of cracks(b)Fig. 1 Resonant frequency of the PZT sensor vs. (a)crack length and (b) crack number

3. Oscillator sensor experiment
Experimental oscillator sensor was fabricated witha feedback oscillation circuit and a PZT patch
attached to an aluminum plate as shown in Fig. 2.
The oscillator circuit was tuned to the lateral mode
resonant frequency of the PZT element and wasused to feedback the resonant signal in response to
the structural condition. Response of the sensor wasobserved while artificial cracks of different depth
were imposed in sequence. PZT is a typicalNormalized frequency

1.000

0.995

0.990

0.985

0.980

d=1

d=2

d=3
d=4
Crack length

d=5

(a)

125500frequency [Hz]piezoceramic generating electricity in response to
an external force. However, the PZT is inherently
also a pyroelectric material that generates electricity
in response to its environmental temperature change.
During the measurement, if the PZT sensor
encounters a change of its environmental
temperature, the sensor generates corresponding
electricity, which will be confused with the realelectric signals caused by structural damages. For
resolution, a dual sensor system was employed,
which consisted of a reference sensor and a real
sensor. The reference sensor was bonded to a small
aluminum plate, and the small aluminum plate was
exposed to the same environment as that for the big
experimental plate specimen. The small aluminum
plate with the reference sensor did not have any
cracks and was stored close to the experimental
specimen. The experimental specimen, thus the real
sensor, was open to the effects of both the cracks
and the environment while the reference plate, thus
the reference sensor, was open to the effect of theenvironment only. Difference of the sensor signals
reflected the effect of the cracks only. Fig. 3 is theresults of the measurements with the PZT oscillator
sensors. As expected from the FEA results, theoscillator sensor showed changes in its oscillation
frequency in proportion to the length and thenumber of the cracks. These results agreed wellwith the results of the FEA, and confirmed thevalidity of the present piezoceramic oscillator
sensor.
However, as illustrated in Figs. 1 and 3, theresponse of the sensor leveled off after a certain
length and number of cracks. Since each crack isapart from its adjacent crack with a constantdistance, a larger number of cracks mean that lattercracks are farther from the PZT patch. Hence, Figs.
1 and 2 can be interpreted as that the PZT oscillator
sensor is not so sensitive to distant cracks as it is tonear cracks. The response of the oscillator sensor islimited to the area near the PZT patch, thus only
local measurement is possible with the oscillator
sensor. For distant cracks, more active methodshould be devised

125400125300125200125100125000
N=1

N=3

N=5

N=7

N=9

N=11

Number of cracks(b)Fig. 3 Oscillation frequency change in relation to the(a) crack length and (b) crack number

4. Conclusions
The feasibility of the piezoelectric oscillator
sensor was verified to detect the damages instructures. The oscillator sensor was composed ofan electronic feedback oscillator circuit and apiezoelectric lateral mode vibrator attached to thestructure of interest. The oscillator sensors could
instantly detect the resonant frequency change ofthe piezoelectric patch in response to the change inthe length and the number of cracks in theexperimental sample plate. Validity of themeasurement was confirmed through comparing theexperimental data with the results of the FEA of theplate with cracks.
Acknowledgment
This work was supported by by Smart
Infra-Structure Technology Center (SISTeC),
KAIST, Korea.

Oscillator
circuit
Piezoceramics

(a)

(b)

Fig. 2 Oscillator sensor; (a) schematic structure of thesensor (b) photograph of the oscillator circuit

References
1. K. K-H. Tseng, and A. S. K. Naidu:. Smart
Mater. Struct. 11 (2002) 317.
2. W. T. Yeung and J. W. Smith: Engineering
Structures. 27 (2005) 685
3. S. H. Park, C. B. Yun and Y. R. Roh: J. NDT&E
Int. 40 (2007) 71.

3P2c-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 387- 388
11-13 November, 2008

Investigation on the reflection and transmissionof Lamb waves across a rectangular crack
Byungsoo Kim ‡, Hyeoksang Kwon and Yongrae(Kyungpook National University, Korea)
1. Introduction
The scattering of a Lamb wave at theboundary of damages has attracted the attention ofmany researchers, and different methods have beenreported as the tool to analyze the phenomenon [1,2]. Most of these methods, however, have theproblem that the field information like
displacements and stresses at crack boundaries ispresented with a single matrix that is called a global
matrix. The dimension of the global matrix is likely
to increase dramatically with the number of crack,
thus it is almost prohibiting to analyze multiple
cracks. In this paper, the repeated and sequential
scattering in the crack is regarded as a summationof numerous scattering cycles, and is divided into
three independent processes. Each scattering cycle
is composed of two of the three processes. Insteadof the single big global matrix, several small local
matrices are composed, and the mode matching
technique is applied to each process [1]. Reflection
and transmission coefficients of a multimode Lambwave across the crack are calculated with these
local matrices per each scattering cycle.
Enforcement of proper boundary conditions,normalization, and superposition of the transmitted
and reflected waves from all the scattering cycles
lead to the overall steady state responses at thecrack boundary.
Properties of the scattered wave are highly
influenced by the geometry of the crack, thus clear
analysis of the dimensional effects of the crack
allows more accurate evaluation of structural
damages. Hence, the efficacy of the method in thispaper is illustrated by investigating the effects ofcrack dimensions on the Lamb wave scattering. The
overall reflection and transmission coefficients areanalyzed in terms of the width and depth of thecrack. Plate thickness is adjusted so that only the S0
and anti-symmetric mode A0 can exist as theincident wave at a given frequency.

When the transmitted wave strikes the boundaries I3
and I4, some portion of that wave is reflected backin R2 while the other portion is transmitted to R3.
The reflected wave strikes the boundaries I1 and I2
again, and some portion is transmitted to R1 while
the other portion is reflected to I3 and I4, and so on.
These scattering processes occur again and again,
and accordingly generate transmitted and reflected
waves to R3 and R1, respectively, until no energy isleft in R2. The scattering mechanism can be divided
into three independent processes as shown in Fig. 1.
Wi is the incident wave, Wr is the reflected wave,
and Wt is the transmitted wave. If a cycle is definedas the combination of the processes to generate areflected wave in R1 (–x direction) and a transmitted
wave in R3 (+x direction), the first cycle comprises
processes 1 and 2, the second cycle comprises
processes 3 and 2, and so on.

I1

Wi1

I2
Wr1
R1
I3

z9810029@gmail.com

Wt2

Wi2
I4
Wr2
R2

R3
(b)

I1

2. Scattering mechanism

‡

R2
(a)

Wt3
A rectangular crack of width (g) and depth(d) in a plate is presented in Fig. 1. If an incident
wave (Wi) strikes I1 and I2 boundaries, some portionof its energy is reflected back in R1, and remained
portion is transmitted to R2.
------------------------------------------------------------

Wt1

Wi3
I2

R1

R2
(c)

Fig. 1 The scattering mechanism: (a) process 1, (b)process 2, and (c) process 3.

3. Analysis
The analysis scheme is applied to analuminium plate. Driving frequency is 100 kHz.
Thickness of the plate (H) is 5 mm, and the size ofthe crack embedded in the plate is changed byvarying the depth (d) from 0.5 mm to 4 mm and byvarying the width (g) from 0 mm to 14 mm,
respectively. In the steady state response, the first
scattering cycle consists of the processes 1 and 2,
and the next cycle consists of the processes 3 and 2,
and so on. The reflection and transmission
coefficients become more and more close to thoseof steady state responses as the iteration number ofscattering increases. For an incident wave of S0 or
A0 modes, the coefficients were calculated in termsof the crack geometry, d and g, and are presented in
Figs. 2 and 3. Fig. 2 shows that the magnitudes oftransmission and reflection coefficients induced by
S0 incidence decrease and increase, respectively, as
the depth (d) of a crack increases, whereas they are
not affected so much by the width (g) of a crack. In
contrast to the case of S0 incidence, it is shown in
Fig. 3 that the magnitudes of the coefficients
induced by A0 incidence are relatively sensitive tothe variation of g as well as d, and they are
fluctuating in a certain pattern and have many
points of inflection. As expected, the responses of
A0 incidence are more sensitive to the geometricvariation of the crack than that of S0 incidence
because the wave length of A0 is much smaller thanthat of S0. In the case of the crack width close to ‘0’,similar mode conversion was reported by
Flores-López et al [3].

(a)

(b)
Fig. 2 Reflection and transmission coefficients when an
S0 mode wave is incident; d/H (%) is the ratio of crackheight/plate thickness: (a) transmission coefficient of S0,(b) reflection coefficient of S0

4. Conclusions
The local matrix scheme in this paper allows
quantitative examination of the characteristics of
the Lamb waves scattered by a defect in a much
simpler manner than traditional methods. The
technique is applicable to assess the health of astructure for ultrasonic non-destructive testing
purposes [4].

(a)Acknowledgment
This work was supported by by Smart
Infra-Structure Technology Center (SISTeC),
KAIST, Korea.
References
1. A. Lakhtakia, V. V. Varadan and V. K. Varadan:
J. Acoust. Soc. Am. 80 (1986) 311.
2. A. Gunawan A and S. Hirose: J. Acoust. Soc. Am.
115 (2003) 996.
3. M. A. Flores-López M A and R. D. Gregory: J.
Acoust. Soc. Am. 119 (2006) 2041.
4. S. H. Par, C. B. Yun, Y. R. Roh and J. Lee:
Smart Materials and Structures 15 (2006) 957.

(b)Fig. 3 Reflection and transmission coefficients when A0
mode wave is incident; (a) transmission coefficient of A0,(b) reflection coefficient of A0

3P2c-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 389- 390
11-13 November, 2008

Acoustical Detection of Internal Cracks of Square
Billets
角鋼片の内部欠陥の超音波による検出
Hideto Mitsui1‡, Koichi Mizutani1, Naoto Wakatsuki1 and Masaki Yamano2 (1 Univ.
Tsukuba; 2 Sumitomo Metal Industries,Ltd. )三井秀人 1‡，水谷孝一 1，若槻尚斗 1，山野正樹 2 （1 筑波大院・シス情工；2 住友金属・総技研）

1. Introduction

2. Principle of measurement
2-1. Measurement of times of flights of longitudinalwave
We detected internal cracks using times offlights of longitudinal wave. Longitudinal wave isthe fastest elastic wave. First received wave isalways longitudinal wave regardless of thecondition of the area. This method can avoid theinfluences of other waves and mode transformation.
Figure 1 shows transmitted wave anddiffracted wave from a crack. Figure 1(a) shows theno crack case. In Fig. 1(b), incident wave isdiffracted by the crack because that is cavity. pT istransmitted wave, and pD is diffracted wave fromthe crack. Figure 2 shows times of flights of pT and
pD. Times of flights of pD are longer than that of pT.
Then, a sound velocity of the crack part is lower
than the around area. Difference of the sound-----------------------------------------------------------mitsui@aclab.esys.tsukuba.ac.jp

Array

Air
Billet
Crack
pD

pT

(b) with crack(a) Without crack

Fig.1 Transmitted wave ( pT ) and diffracted wave froma crack ( pD )Amplitude

The detection of defects in screws andcoils is difficult because of their complicated shapes.
So it is important to detect internal cracks of billets
before screws and coils are manufactured. In
addition, the accuracy for the ultrasonic testingof the billets is required to be improved thequality of manufactures1). The detection of internalcracks of billets mainly uses the pulse echo method
although there are other methods for the ultrasonic
testing2,3). This method has some difficulties fortreating elastic wave and mode transformation
caused by the cracks. And the detection is
inaccurate in some case because this method iseasily affected by the shape and the direction of thecracks.
In this paper, we propose a method for areconstruction of internal cracks using times offlights of longitudinal wave. It is possible toreconstruct the internal cracks using the soundvelocity calculated from the times of flights oflongitudinal wave. The crack detection isnumerically tested based on the simulation of the
wave propagation using the transmission-line
matrix (TLM) method.

With crack
Without crack

TOF of pD
TOF of pTTime differenceTime

Fig.2 Times of flights (TOF) of pT and pD

velocity makes possible to measure with or without
the crack.
2-2. Reconstruction of internal cracks using theMatrix method 4)
A measurement area is partitioned into (m,n) cells. The relationship between times of flights oflongitudinal wave and the sound velocity is givenby
T=L⋅X,(1)
where T is the times of flights of longitudinal
waves, L is the lengths passing through the cells
and X is the inverse number of the sound velocities
in the cells. Sound paths are approximated bylines connecting the transmitters and receivers. The
number of the sound paths accords with that ofmeasured data. The number of cells is m × n. T and
X are column vectors whose sizes are equal to thenumber of the sound paths, L is a matrix whose sizeis (the number of the sound paths × the number ofthe cells). Solving eq. (1) yields,
X = L+ ⋅ T ,

(2)

50

2

y

(50 elements)

5800
5700
5600

-25
20

Crack

x

y (mm)

00

5900

0

10

100

6000

(b) θ = 30 °

25

D

θ

(a) θ = 0 °

5500

-50
(c) θ = 60 °(d) θ = 90 °

25

100

0

Fig.3 Simulation field of billet and internal crack-25

where L+ is a generalized inverse of L. It is possible
to reconstruct an apparent sound velocity
distribution, which is expected to be related to theinternal cracks

-50
-50

The simulation of the wave propagation
uses the TLM method5,6). The TLM method is basedon the Huygens’ principle, which gives the time
domain solution of the wave field. This study uses
potential wave in view of only longitudinal wave.
Other waves such as shear waves and surface waves
are neglected.
Figure 3 shows a simulation field of abillet and an internal crack. The billet is assumed to
be steel (the sound velocity is 5900 m/s, the density
is 7700 kg/m3). The size of the billet is 100 mm
square. The center of the billet is taken as the origin.
The crack is located at 20 mm to x-axis and 10 mm
to y-axis. The depth of the crack is D mm, the widthis 0.2 mm and the direction is θ °. Linear arrays are
set all around the billet. Each array has 50 elements,
and the element pitch is 2 mm. The length of thearray is 100 mm. The sampling frequency is 50.0
MHz. The transmitted signals are down chirp
signals of 2.0 ± 1.0 (MHz).
Figure 4 shows the images of internalcrack reconstructed from the simulation when D is
10 mm. Figure 4(a), (b), (c) and (d) show the resultsof θ = 0, 30, 60 and 90°, respectively. The locationsof reconstructed crack in Fig.4 are in accord withthose of the crack of the simulation field. Therefore,
the internal crack can be detected exactly regardlessof the direction of the crack. The direction of thecrack conforms with θ. The depth of the crack isapproximately equal to D. Figure 5 shows theimages reconstructed from the simulation when
θ is 60° with various depth D. Figure 5(a) and (b)respectively show the results of D = 5 and 2 mm.
The detection of the location of crack in Fig. 5 is as
accurate as that in Fig. 4. Since the wavelength of
the transmitted signals is 3 mm, it is possible todetect internal crack even if the depth of the crack

025-50 -25x (mm)

0

25

50

Fig.4 The images of internal crack reconstructed fromthe simulation. D = 10 mm. (a), (b), (c) and (d) show
results of θ = 0, 30, 60 and 90 °50(a) D = 5 mm

6000(b) D = 2 mm

5900

25
y (mm)

3. Simulation results

-25

5800

0

5700
5600

-25
-50
-50

5500
-25

0

25

-50 -25x (mm)

025

50

Fig.5 The images reconstructed from the simulation. θ= 60°. (a), (b) show results of D = 5, 2 (mm)is shallower than the wavelength.
4. Conclusions
Through the simulations, the location ofinternal crack could be detected exactly regardlessof the shape and the direction of the crack. This is
expected to be useful for the ultrasonic testing. The
determination of the direction and shape of thecrack remains as future work. The treatment ofelastic waves as vector wave is also planned.
References
1.
H.Yamaguchi,
N.Matsubara,
K.Fujisawa
andS.Matsumoto: ISIJ. 70 (1984) 1210.
2. M.Ohno, T.Kato, A.Kokubo and K.Yamamoto: Jpn. J.
Appl. Phys. 44 (2005) 4421.
3. R.Sasaki, T.Ogata, Y.Ohara, T.Mihara and K.Yamanaka:
Jpn. J. Appl. Phys. 44 (2005) 4389.
4. K.Sawamura, K.Mizutani, Kashiwazaki and I.Odanaka:
The 26th Symposium On Ultrasonic Electronics (2005)
237.
5. P.B.Johns and R.L.Beurle: Proc. IEE, vol.118, No.9
(1971) 1203.
6. W.J.R.Hoefer and P.P.M.So: John Wiley & Sons (1991)

3P2c-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 391- 392
11-13 November, 2008

Visualization and modal analysis of guided waves from a
defect in a pipe
Nor Salim Bin Muhammad, Takahiro Hayashi, Morimasa Murase, and Shoji Kamiya(Faculty of Engineering, Nagoya Institute of Technology)

1. Introduction
In our previous study, a robot arm and laser
Doppler vibrometer were used for visualizing
reflected waves in two regions around defect from alarge number of waveforms measured on thesurface of pipe [1]. To acquire more information of
the propagated wave from defect, guide waves in
the whole circumference of pipe around defect are
visualized in this study to demonstrated thecomponents of in plane and out of plane vibrations
occur in the pipe surface respectively. We also
further improved the visualized inspected areas byapplying two difference signals processing
emphasizing the signal of reflected wave andeliminating the incident wave excited from the usedmagnetostrictive transducer [3].
2. Laser scanning technique
In order to visualize guided wave propagation
on a surface of an object, we collect waveforms

LABVIEW

PCI

at many points on the surface of the object with
sufficiently small distance compared to the laser
wavelength. The entire system is controlled by a PC
as described in Fig.1, where the robot arm iscontrolled to move the focal point of laser beamaccording to scanning locations and to tilt the laser
beam to the determined directions. At the same time
axisymmetric torsional mode, T(0,1) is excited at
frequency 70 kHz from a magnetostrictive
transducer which attached enclosing the pipe
circumference to vibrate the pipe.
This paper presents guided wave inspections oftest pipes which have two different artificial defects
on the surface of aluminum pipes with dimensionsof 4 m in length, 110 mm in outer diameter and 3.5
mm in thickness. The artificial defects on the pipe
surfaces are shown in Fig.2 which Fig.2(a) consistsof a file notch stretching in the circumferential
direction and Fig.2(b) shown a file notch stretchingin the oblique direction at angle of about 45° to thehorizontal direction. Both defects were made in thesize of about 40 mm in length, 10 mm in width and
2 mm in depth using a file at 500 mm from end of
the pipe.

GPIB
LAN

A/D board(NI: PCI-6115)

Function generator(NF: WF1994A)

Power amplifier
40 dB up
(NF: HSA4052)
Robot arm
(Mitsubishi: RV6S)
Laser doppler
vibrometer(Ono sokki: LV-1720)(a) Circumferential defect
Fig.2(b) Oblique defect

Artificial defects made on pipe surfaces

The enclosed surfaces on pipe circumference
are scanned at many points on retro-reflection tapes
attached on 12 of the scanning regions as shown in
Fig.3 to improve the reflection of laser beam when
scanning the surface of pipes [1].
4.0 mDetect vibration
Laser beam

Magnetostrictive
transducer

Z=0 mm Z=500 mm
Row I
Region 1-1

110 mmDefect

Z=700 mm Z=910 mm
Row II
Region 2-1

T(0,1) mode
Magnetostrictive transducer

Fig.1 Laser scanning system-----------------------------------------------------------E-mail address: chd16510@stn.nitech.ac.jp

Scanning region

Oblique file notch(a) Configuration of test pipe

Scanning region

Oblique file notch

200 mmRegion 1-1

3.5 mm50°

Region 2-1

Region 1-2
Region 1-3

Region 2-2

Region 2-3(b) Scanning regions on pipe surface
Fig.3

Visualized guided wave propagations

reflected and excited incident wave which is still
remained in the visualized in plane vibration
modes.
4.

In the second signal prosessing technique usedin this study, we eliminate the incident wave to
make the propagation uncomplicated and easy tounderstand. The visualized images from thesewaveforms are shown in Fig.6 and 7 where theexcited incident wave is successfully removed fromthe in plane vibration modes.

Fig.3(a)illustrates
thelocationofmagnetostrictive transducer, scanning regions anddefect on the pipe. RF signals of guided waves werecollected in the scanning area along 50° of
circumferential and 200 mm of longitudinal
direction in each scanning area as shown in Fig.3(b).
Then, the collected RF signals from each scanning
region on pipe surface was visualized in timeframed images and regroup as a large image which
demonstrate the simultaneous vibration of reflectedwave from defect at each scanning position.
3.

Elimination of incident wave(a) In plane vibration
modes
Fig.6

(b) Out of plane vibration
modes

Simplified reflected wave fromcircumferential defect.

Emphasizing reflected wave from defect(a) In plane vibration
modes(a) In plane vibration
modes
Fig.4

Fig.5

(b) Out of plane vibration
modes

Emphasized reflected wave fromcircumferential defect in pipe.

Emphasized reflected wave from obliquedefect in pipe.

The visualized propagation of reflected wave
for each mode can be obtained directly fromsimultaneous vibration at each scanning location.
On the contrary, identification of existing defect isstill difficult since the visualized image does notclearly demonstrate the propagation of reflectedwave from defect. This is caused by theinsignificant amplitude of reflected wave compare
to incident wave and also interference of theincident wave to the reflected wave. Visualized
guided wave propagations from the emphasizedreflected wave are shown in Fig.4 and 5 where thepropagation of stripes representing the behaviors of

Fig.6

5.

(b) Out of plane vibration
modes

Simplified reflected wave from oblique defect.

Conclusions

The incident wave of an axisymmetric torsionalmode and reflected waves from defects are clearlyshown for whole circumference of pipes. The
visualization results exhibit the profiles of thereflected waves associate with the orientation andshape of defects on the pipe surface. This is proved
as the reflected waves from circumferential defectpropagate in circumferential direction of the pipe in
opposite direction to incident waves and reflected
waves from oblique defect propagate inclined atangle 45° according to the orientation of defect in
opposite direction to incident waves.
References
1. T. Hayashi, Y. Kojika, K. Kataoka and M.
Takikawa Review of progress in QNDE 27A(2007) pp.178-184.
2. S. Yashiro, J. Takatsubo, H. Miyauchi and N.
Toyama NDT & E International 41(2) (2008)
pp.137-144.

3P2c-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 393- 394
11-13 November, 2008

Defect detections of pipes using guided waves generated byan efficient transduction method with a reflector
反射体を利用した高効率ガイド波
励起検出法による欠陥の検出
Hideo Nishino, Keiji Ogura and Kenichi Yoshida (The Univ. of Tokushima)
西野秀郎, 小倉圭二, 吉田憲一 （徳大院）

1. Introduction
Guided waves propagating in the axial
direction of pipe [1, 2] have been anticipated for an
efficient nondestructive inspection tecnique becauseof their capability of long range propagation. But inthe case of pipes having high propagation
attenuations, e.g., buried- and embedded-pipes, thepropagation distances and inspection area become
extremely short due to their energy leakge to thesurrunding materials. Therefore an improvement oftransduction efficiency of guided wave is one of theinvariable and continuous themes for the
exploitation of the guided wave inspection. The
authors proposed an efficient transduction methodwith wave reflectors [3]. Efficient transduction has
been realized by using the reflector located at an
optimum axial position apart from the sensor.
While a similar method that can be applied only at
the pipe edge has been already reported [4], ourmethod has been able to be applied to any positionof the pipe. In this paper, experimetal investigationsof defect detections by the efficient method aredescribed. Experiments were carried out with thepiezoelectric ring sensor system. Sensitivity withthe reflector for defect detections was 2 – 2.5 times
larger than that without the reflector.
2. Principle of the efficient transduction [3]In general setting of the ring-shaped sensor
for guided wave generation, guided waves are
generated in both sides along the axis of the pipe,
here we call those waves left- and right-propagatingwaves, respectively. When the ring-shaped reflector
fixed around the pipe is located just right side of thesensor, the right-propagating wave reflects at thereflector and its propagating direction is changed(As a matter of fact, multiple reflection is occurred
between the sensor and reflector). These two waves
are overlapped each other. When the distance L
between the sensor and the reflector equals the nλ/2 (λ:wavelength of guided wave), amplitude of theguided wave increases due to the interference. As
for the efficient detection, a similar manner of theinterference is took place either.
3. Experimental verification of defect detection
Figure 1 shows the experimental appartus. A
60.5 mm outer diameter and 4 mm thick aluminumnishino@me.tokushima-u.ac.jp

Fig. 1 Schematic illustration of experimental apparatus(Al) pipe was used as a specimen. The ring-shaped
piezoelectric transducer system was employed.
Nowadays, this system and the magneto-strictive
sensor (MsS) system are de fact standard systems
for guided wave inspection. The piezoelectric
system is consisted of two sets of eightpiezoelectric elements. The elements of each set arelocated at 45˚ interval on circumferential position of
the pipe. The two sets were respectively used as a
generator and a reciever as shown in Fig.1. 2 mm
thick lead (Pb) plate was sandwitched between aniron hose-fixing belt and the pipe surface was usedas the reflector in the experiments. Gaussianenveloped tone-burst signals were used to generate
the T(0,1) mode guided waves. The measured
propagation velocity was 3120 m/s. The frequency
was 50 kHz (λ = 62 mm).
In order to compare the sensitivities with andwithout the reflector, following experimental
procedure was carried out. (1) The reflector was set
as shown in Fig. 1 then the propagation direction
was left. In this setting, the artificial defect was
gradually increased (about 0.05 mm step) at the left
side and was inspected. (2) The reflector was
released then the propagation direction was bothside. The other defect was introduced at the rightside and was also inspected in the same manner of(1). The artificial defects were produced by thesmall grainder as shown in Fig. 2.
4. Results
Time domain signals generated and detectedby the piezoelectric system at the defect having
1.65 mm depth (cross-sectional loss: 3.06%) withand without the reflector were shown in Figs. 3 and4, respectively. It was confirmed that the amplitude

d = 10mm
1.64mm(3.06%)

1.5

Relative amplitude (a.u.)

Fig. 2 Schematic side view of a pipe and defect.

1.0

0.5
Fig. 3 Time domain signal obtained with the reflector.

1.59mm(2.92%)
1.56mm(2.84%)
1.51mm(2.70%)
1.45mm(2.54%)
1.40mm(2.41%)
1.31mm(2.19%)
1.25mm(2.04%)
1.19mm(1.89%)
1.15mm(1.80%)
1.11mm(1.71%)
1.04mm(1.55%)
0.99mm(1.44%)
0.94mm(1.33%)
0.90mm(1.25%)
0.84mm(1.13%)0.80mm(1.05%)
0.75mm(0.95%)
0.69mm(0.84%)
0.64mm(0.75%)
0.60mm(0.68%)
0.54mm(0.58%)
0.50mm(0.52%)
0.44mm(0.43%)
0.40mm(0.37%)
0.34mm(0.29%)
0.30mm(0.24%)
0.25mm(0.18%)
0.20mm(0.13%)
0.15mm(0.09%)
0.11mm(0.05%)

0.0
0.4

0.06mm(0.02%)
0.00mm(0.00%)

0.5

0.6

0.7

0.8

0.9

1.0

Propagation time (ms)Fig. 5 Enveloped signals for different depth defects.

Fig. 4 Time domain signal without the reflector. The
first wave packet indicates the signal of the left side
defect which had already introduced in the previous
experiment with the reflector.

obtained with the reflector was 2.5 times larger
than that without the reflector. Enveloped time
domain signals with the reflector for the different
cross sectional losses (0% - 3.06%) are shown in
Fig. 5. It was confirmed that the amplitude was
obviously increased with increasing the crosssectional loss. Amplitude obtained with thepiezoelectric transducer system as a function ofcross sectional loss was shown in Fig. 6. Circles
and squares in Fig. 6 indicate the amplitudes withand without the reflector, respectively. The
minimum cross sectional loss that could be obtainedwith and without reflector was almost same ataround 0.5%.
5. Conclusions
Evaluations of an efficient guided wave methodwith a reflector for defect detections were carriedout by using the piezoelectric sensor system. It was
confirmed that the sensitivities of the method withthe reflector were 2 - 2.5 times larger than those
without the reflector.

Fig. 6 Amplitude as a function of cross sectional loss.

Acknowledgement
This work was done as a part of the Nuclear
and Industrial Safety Agency (NISA) Project on
Enhancement of Ageing Management andMaintenance of Nuclear Power Plants.
Reference
1. J.L.Rose, Ultrasonic wave in solid media(Cambridge univ. press, Cambridge 1999).
2. H. Nishino et al, JJAP 40 (2001) 354.
3. H. Nishino et al, Proc. ICM&P 2008, accepted.
rd
4. T. Yamasaki et al, Proc. 3 US-Jpn symp Adv.
Appl. and Capabil. in NDE (2005) 426.

3P6-8Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 395- 396
11-13 November, 2008

Biodiesel production from virgin and waste oils
using ultrasonic reactor in pilot scale
Le Tu Thanh†, Kenji Okitsu, Yasuhiro Sadanaga, Norimichi Takenaka,
Hiroshi Bandow (Osaka Prefecture University)

Introduction
Currently, most of the biodiesel fuel (BDF) is
produced by the transesterification reaction of oils
with methanol in the presence of alkaline catalysts
using mechanical stirring method at temperature
50-65oC [1]. This method consumes much energy
because reactants must be heated up to desired
temperature to occur the reaction, and also requires
rather long reaction time (1-4 hours). Many studies
have been done to reduce the production cost suchas by the use of waste oil [2], various catalysts [3],continuous process [4]. Ultrasound irradiation canstimulate the reaction at room temperature, and thereaction time can become much shorter thanmechanical stirring, therefore energy can be saved.
In this study, BDF production in the pilot scale was
performed by circulation process under low
frequency ultrasound (20 kHz) with the input powerof 1 kW. Effect of various process parameters suchas the amount of KOH, molar ratio of oil tomethanol and also reaction time were investigated.
Experimental procedure
Materials and apparatus
Canola oils were of commercial edible grade. Waste
vegatable oils were those after domestic use,collecteted by municipal activities, and settled toremove food remainning in the oils. Potassiumhydroxide (95.5%) and methanol (99%) werepurchased from Wako Pure Chemical Industries.
Dr. Hielscher ultrasonic transducer model UIP 2000
having a frequency of 20kHz and total power of
1kW was used as an ultrasound source, andconnected to a reactor with the working volume of
3L. System to separate glycerin and crude biodiesel
fuel (BDF), and to purify BDF was designed by
Kimura Chemical Plants Co., Ltd with the capacityof 100L/one batch process.
Procedure
The experimental setup system is schematically
depicted in Fig.1. In each experiment, 54L oil andmethanol in a given molar ratio containing KOH
were fed to the reactor and a circulation tank by apump. The feeding ratio of reactants was controlled
by a valve system. After 10 minutes, all reactants
were transferred to the circulation tank. Feeding
valves for oil and methanol were closed, and thecirculation valve was opened. Then the circulationof the reactants was curried out for 60 minutes. The
reaction mixture was settled overnight to separate
glycerin, excess methanol, and crude BDF. The
crude BDF was purified by washing 3 times withtap water (water to BDF: 20% v/v), and dried byheating up to 65oC with a mild flushing of a dry air
under reduced pressure at 520torr.
US Transducer

Reactor

Methanol + KOH
Circulation
tank

Pump

ControlvalvesOil

Fig.1 Schematic diagram of the setup of ultrasoniccirculation process for BDF production

Analysis
Reactant and products were determined by HPLC
(Shimadzu LC-6A HPLC pump with RID 10A
detector). The column used was Cadenza CD-C18,
25cmx3.0mm with 4µm particle. Mobile phase wasan acetone/acetonitrile: 70/30 v/v, with a flow rateof 0.4ml/min. Using the standard chemicals, triolein,diolein, monoolein and methyl oleate (from Sigma
Aldrich Corporation), calibration was made for thequantification of triglycerides (TGs), diglycerides(DGs), monoglycerides (MGs), and fatty acidmethyl esters (FAMEs). 5mL samples were takenfrom the circulation tank, and neutralized by 1ml of
H3PO4 5% aqueous solution to stop reaction. About
70mg sample was diluted in 10ml of the mobile
phase and injected to HPLC.
Results and discussion
Changing of concentration of reactants versus time

Figure2showstheprogressoftransesterification reaction for canola oil. The
concentration of KOH was 0.7%, and theoil/methanol molar ratio was 1:5. In the initialstage of the reaction, conversion of TGs andalso the yield of FAMEs were rapid. The ratethen decreased and approached to equilibriumin about 50 min; after 70min, TGs and FAMEs
concentration were 2.5% and 95%, respectively.
The highest concentration of MGs and DGs
were observed in the first 10 min reaction. Thechanging of the reactant and products in thewaste oil was almost the same as canola oil.

80
MGs
60

DGs

40

TGs

100
[FAMEs]/ % w/w

Rel. conc./ % w/w

100methyl ester (FAMEs). The optimal conversion of
FAMEs achieved was 95% at the molar ratio of oil
to methanol being 1:5 (Fig.4). It is note worthy the
results show the lower the molar ratio the faster theconversion in the initial stage of the reaction(10min). This fact may imply that under ultrasoundirradiation at the initial stage with small amountmethanol, small size droplet of methanol wasformed rapidly and easily dissolved in oil phaseleading to emulsion, so that the reaction could takeplace rapidly.

FAMEs
20
0
0

10

20

30
40
Time /min

50

60

70

In the experiments done in this study, concentrationof KOH was in the range of 0.5-1.0 % w/w (KOHto oil). The effect of catalyst amount on theconversion efficiency is shown in Fig.3. The
maximum conversion of FAMEs achieved 95% at
0.7% of KOH. Increasing amount of catalyst led to
the formation of soap, and thus washing andpurifying BDF became difficult. However, optimal
concentration of KOH was 1% in the case of waste
oil containing high concentration of free fatty acid
(FFA about 1.7%).

[FAMEs]/ % w/w

100
80
60
KOH 0.5%40

KOH 0.7%

20

KOH 1.0%

0
20

30
40
Time/min

40
20

0

10

20

30
40
Time /min

50

60

70

Fig.4 Effect of the molar ratio of oil to methanol on theconversion of FAMEs. Concentration of KOH was 0.7%

Effect of KOH catalyst amount

10

1:4
1:5
1:6

60

0

Fig.2 Time profile of reactant and products fortransesterification reaction of canola oil to FAMEs withmolar ratio of oil to methanol 1:5, KOH 0.7%

0

80

50

60

70

Fig.3 Effect of KOH catalyst amount on the conversionof FAMEs. Molar ratio of oil to methanol was 1:5

Effect of molar ratio of methanol to oil
An excess amount of methanol is necessary for thetransesterification of TGs and methanol. Because
the transesterification is an equilibrium reaction, thelager amount of methanol can enhance themethanolyis to result in the equilibrium favorable to

The chemical compositions in BDF products
obtained in this study are summarized in Table 1.
Table 1: Main components of BDF products
Oil
CanolaCanolaCanolaCanolaWaste

Oil:MeOH
1:4
1:5
1:5
1:6
1:5

KOH%
0.7
0.7
0.5
0.7
1.0

MGs
1.1
0.5
1.2
1.5
1.5

DGs
3.1
1.9
2.4
2.8
2.5

TGs
2.6
1.3
2.3
1.3
4.0

FAMEs
93.2
96.3
94.1
94.4
91.6

Conclusion
The above results show that transeterification
reaction of virgin and waste oils with methanol
in the presence of catalyst KOH assisted byultrasound is very efficient. This process saves
energy consumption, reduces reaction time aswell as soap formation. The optimal conditions
are found as molar ratio to oil to methanol 1:5;
amount of KOH 0.7% and 1% for virgin andwaste oils, respectively. Under these conditions,the yield of FAMEs archives 96.3% for virgin
oil and 91.6% for waste oil.
References
1. A.S. Ramadhas, S. Jayaraj, C. Muraleedharan:
Fuel 84 (2005) 335-340.
2. A.V. Tomasevic, S.S. Siler-Marinkovic: Fuel
Process. Tech. 81 (2003) 1-6.
3. S. Gryglewicz: Biores. Tech. 70 (1999) 249-253.
4. C. Stavarache, M. Vinatoru, Y. Maeda, H.
Bandow: Ultrasonics Sonochem., 14 (2007)
413-417.

3P6-9Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 397- 398
11-13 November, 2008

Ultrasonic Soil Washing with Surfactantsfor the Remediation of Diesel-Contaminated Soil
Jihoon Cha‡, Beomguk Park, Younggyu Son, Mingcan Cui, Jeehyeong Khim†(Department of Civil, Environmental and Architectural Engineering, Korea University)

1. Introduction
Sites that have been contaminated by petroleumhydrocarbons (PHCs) have been recently reported[1-5]. Soil contamination with PHCs has beencaused by the leakage of underground storage tanks
in various sites such as gas stations, military bases,
and industrial complexes etc. Soil remediation canlead to long term contamination of ground water
through rainfall, if it is not timeously removed [1].
There are various remediation technologies thatcan be used for soil remediation (e.g. vapor
extraction, pump and treat, flushing, washingetc.)Of these technologies, soil washing takes theshortest time to process and shows the highest
efficiency. Recently, a number of researchers haveused ultrasound for the remediation of soil (heavy
metals, diesels, etc.) [1-5]. Ultrasound causes
physical effects (microjet, microstreaming, shockwave) by cavitation. These effects can enhance themass transfer from the solid phase to the liquid
phase.
In studies on ultrasonic irradiation, research has
been carried out on the efficiency of diesel removal
depending upon a variety of variables (soil andliquid ratio, power intensity, surfactants etc.) [1-6].
However, minimal research has been conducted on
the relationship between power intensity andreaction time when inserting the same type ofenergy.
In this study we compared the effects of diesel
removal in soil polluted by diesel, with the same
input energy (different power intensities andreaction times). The effect of surfactant on theremoval of diesel was then examined.
2. Experimental procedures
The sonoreactor used herein consists of astainless steel reactor, pentagon shape and-------------------------------------------------------------hyeong@korea.ac.kr

ultrasonic transducer module (Mirae UltrasonicTech.) placed on the reactor wall. Each transducer
module contained three PZT transducers (Tamura
corp.) and could produce ultrasounds of 35, 72, 110
and 170 kHz. The maximum power of thetransducer module was 500 W. The reactor was
filled with 5 L of tap water. A 50 mL reactor cell
containing contaminated soil and washing water
was submerged in a sonoreactor. Fig. 1 shows aschematic of the experimental apparatus.
Jumunsin sand was sieved using a mesh size
ranging from 30 to 40 and the range of particle size
was therefore 0.4~0.6 mm. The soil was
contaminated with diesel (using n-pentane) for 15
days. The initial concentration of diesel in the soil
was 7,000 mg/kg.

Fig. 1 Schematic of reactor

An ultrasound irradiation experiment was
carried out after the n-pentane in the soil had
completely evaporated. The bath type sonicator(Flexonic, Mirae Ultrasonic Tech.) with a frequencyof 35 kHz and 50, 100, 200, and 400 W of power
was used. A mixture of 10mg contaminated soil and
20mL water was added into a 100mL cylindricalbath reactor and sonicated for 5, 10, 20 and 30 min.
Observations of the effect of the surfactant wereconducted using sodium dodecyl sulfate (SDS)
20mM. The reaction temperature was kept constantat 25±2℃ by a water cooling system.
After sonication, the sample was placed into acentrifuge operated at 4000 rpm in order to separate
solid and liquid phases. The diesel concentration in

3.

Results and Discussion

To determine the optimal condition of irradiation
for ultrasonic soil washing, various sets of input
power and irradiation times were applied in the caseof 35 kHz. The results shown in Fig. 2 revealed thatremoval efficiencies were almost the same for thefour combinations when the total input energy wasconstant.

100

80

Removal efficiency (%)

the solid phase was then extracted by using
dichloromethane and measured for total petroleumhydrocarbon content (TPH) with a GC-FID(Agilent, 6890).

60

40

20

0
0

100

200

300

400

Input power (W)Fig. 3 Diesel removal efficiency for various input powers
100

60
80

Removal efficiency (%)

Removal efficiency (%)

50

40

30

20

60

40

SDS+US
US

20

10
0

0
400W-10min

200W-20min

100W-40min

50W-80min

0

5

10

20

30

Irradiation time (min)Input power and irradiation time

Fig. 2 Diesel removal efficiency for various
combinations of input power and irradiation times

Fig. 4 Diesel removal efficiency for only ultrasound andcombination of ultrasound and surfactant

Fig. 3 shows the diesel removal efficiency forvarious input powers. Irradiation time was 30 min.
As input power increased, the removal efficiencies
increased. However, the improvement of removal
efficiency was not as significant as expected. This
indicated that while a certain amount of pollutants
could be readily desorbed from the soil using
ultrasound, diesel removal was not effectively
enhanced as the input ultrasonic energy increased.
As shown in Fig. 4, the addition of surfactant
could effectively improve removal efficiency.
Surfactants could be promoted by the mass transfer
of hydrophobic compounds into a hydrophilic phaseand the cavitation event could occur more violently
due to bubble coalescence inhibition.

Acknowledgments
This subject is supported by Ministry ofEnvironment, Republic of Korea as “The
Eco-technopia 21 project” (no. 061-081-042).
References
1. G. J. Price and M. McCollom : Ultrasonics
Sonochemistry 2 (1995) S67.
2. D. Feng and C. Aldrich : Advances inEnvironmental Research 4(2000) 103-112
3. D. Feng, L. Lorenzen, C. Aldrich and P. W.
Máre : Minerals engineering 14 (2001) 1093.
4. Y. U. Kim and M. C. Wang : Ultrasonics 41(2003) 539.
5. S. Na, Y. Park, A. Hwang, Y. Kim and J. Khim :Jpn. J. Appl. Phys 46 (2007) 4775.
6. A. Collasiol, D. Pozebon and S. M. Maia : Anal.
Chim. Acta 518 (2004) 157.

3P6-10Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 399- 400
11-13 November, 2008

Relationship between the lactic fermentation promoted
by ultrasound and the fermentation temperature
超音波による乳酸発酵促進と発酵温度との関係
Satoshi Koyama† and Nobuyoshi Masuzawa (Musashi Institute of Technology)
小山聡†，増澤信義（武蔵工業大学）

1. Introduction
Various kinds of food processing using lactic
acid bacteria are carried out. Among them, yoghurt
and kefir are representative products. By adding
lactic bacteria to milk, they are produced throughlactic acid fermentation1,2). We have carried out
the studies on the promotion of fermentation byirradiating ultrasound in this process3,4). Up tonow, the following is the result of our study.
Fermentation promotion with ultrasound isdependent on the frequency and the sound pressureof irradiating ultrasound5,6). However, mechanismof promotion effect has not been made clear yet.
One of ultrasonic actions is temperature rise by theabsorption of ultrasonic energy. In this study, we
experimentally examined in the fermentation
temperature of the lactic acid fermentation and theinfluence of temperature rise with ultrasonicirradiation.
2. Relationship between fermentation temperature and temperature rise with ultrasonicirradiation
It is known that the lactic acid fermentation isstrongly dependent on the fermentation temperature.
Fermentation temperature of kefir used in this study
is appropriate around 20～30oC from the noticedelivered from the company.
We made anexperiment in order to know the optimum
fermentation temperature in the case of noultrasonic irradiation. Solidification time withultrasonicirradiationiscomparedwithsolidification time without ultrasonic irradiationnear the optimum temperature. We examine therelationship between the fermentation temperatureand promotion effect of the lactic acid fermentation.
It is considered that if the temperature of themilk rises with ultrasonic irradiation, thefermentation is promoted and solidification time isshortened below the optimum temperature and thefermentation is suppressed and solidification time islengthened above the optimum temperature. If thepromotion of the lactic acid fermentation does not
relate to temperature rise, it is considered thatbehavior of the lactic acid bacterium is activated byother effects of ultrasonic irradiation.
3. Measurement method
Water is filled into a water tank made ofacrylic resin, and water temperature is kept constantwithin ±0.1oC using a circulation-type temperature
regulator. 500 ml of milk in a bag of thinpolyethylene was placed in the tank. By adding
1 g of inoculum bacteria to the milk, the mixture isagitated. Defining this moment as the beginningof fermentation, pH is measured in every one hour.
The colloid particles become insoluble when lactic
acid fermentation advances and pH drops. The
time when fermentation is achieved (solidification)
is defined as the time when pH becomes 5.0, whichis the pH of a kefir product. Ultrasonic frequencies
were changed by installing vibration systems ofdifferent frequencies. The frequencies were 20,
150 and 250 kHz. In order to avoid the effects ofstanding waves, sound absorber material was placedat the both sides of the tank and opposite thevibration system. The sound pressure is 10 kPa
constant.
Sound pressure is measured beforehand using
sonic meter SM1000 (Shinka Industry). The
inoculum used in this study is a highly activatedkefir fungus of Nakagaki Co. made by thefreeze-drying process. 1000 ml paper-packed milkwith 3.5% milk fat was used.
4. Measured results
At first we made experiment in order toobtain the optimum fermentation temperature
without ultrasonic irradiation. Figure.1 shows theresult of the experiment. As shown, the optimum
temperature is 29oC.
It is considered thatsolidification time is shorted below 29oC andlengthened above 29oC with ultrasonic irradiation.
Since the absorption of ultrasound in the milk isdependent to the ultrasonic frequency, temperaturerise is dependent to the ultrasonic frequency. In
the frequency range, the more frequency is high, the

700

700

S o lid ific a tio n tim e [m in ]S o lid ific a tio n tim e [m in ]

680

680

660

no irrad20 kHz150 kHz250 kHz

640

660

620

640

600
580

620

560
540

600

520

580
27

29

31

33

Temperature [℃]

Fig.1. Solidification time dependent on temperaturein the case of no ultrasonic irradiation

more absorption is high. Therefore we madeexperiments by changing ultrasonic frequencies.
Figure.2 shows the solidification time when
the frequency is changed. Solidification time withultrasonic irradiation is shorter than that of noirradiation in respective temperature. The more
frequencies are high, the more solidification times
are short. If temperature rise with ultrasonicirradiation influences promotion of fermentation,
the lactic acid fermentation is suppressed above
29oC. All the data, however, show the lactic acidfermentation is promoted with ultrasonic irradiationin the measured temperature range.
It is obvious that temperature rise withultrasonic irradiation does not influence promotionof the lactic fermentation. Temperature rise is nota main cause of promotion of fermentation withultrasound and ultrasonic effect dependent on
frequency is large in the measurements in this study.
This is considered that cause of the promotion
might be expansion of chemical site with stirring
effect of ultrasound.

5. Comculusions
In this study, we experimentally examined on
the relationship between promotion of fermentationand temperature rise with ultrasonic irradiation. As

500
27

28

29

30

31

Temperature [℃]3233

Fig.2. Solidification time dependent on temperaturein the case of ultrasonic irradiationa result, it was found that temperature rise withultrasonic irradiation influences promotion of thelactic fermentation very little.

References
1. Y. Uchimura and S. Okada: Nyusankin Jikken
Manuaru (Experiment Manual on Lactic Bacteria)(Asakura-shoten, Tokyo 1992) p.1 [in Japanese]
2. Nyusankin-kenkyu shudankai: Nyusankin-no
Kagaku-to Gijutsu (Science and Technology of
Lactic Bacteria) (Gakkai-shuppan-senta, Tokyo1986) p.226 [in Japanese]
3. N. Masuzawa and E. Ohdaira: “Attempts to
Shorten the Time of Lactic Fermentation by
Ultrasonic Irradiation” Jpn. J. Appl. Phys. 41 (2002)
3277-3278
4. N. Masuzawa, A. Kimura and E. Ohdaira:“Ultrasonic Monitoring of the Progress of Lactic
Acid Fermentation” Jpn. J. Appl. Phys. 42 (2003)
2963-2964
5. T. Shimada, E. Ohdaira and N. Masuzawa:“Effect of Ultrasonic Frequency on Lactic acidFermentation Promotion by Ultrasonic Irradiation”
Jpn. J. Appl. Phys. 43 (2004) 2831-2832
6. K. Katayama and N. Masuzawa : “Frequency
dependence of promotion degree in lactic
fermentation promotion using sound andultrasound” Proc. .The thirteenth International
Congress on Sound and Vibration (2006) RS98-752
pp. 1-8

3P6-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 401- 402
11-13 November, 2008

Enhancement in removal efficiency of tannins
in livestock wastewater using ultrasound/ozone
Junghyun Lim, Eunju Cho, Mingcan Cui, Myunghee Lim and Jeehyeong Khim†(Department of Civil, Environmental and Architectural Engineering, Korea University)

1. Introduction

2. Materials and Methods

In piggery wastewater treatment, there aremany steps that can be used to enhance processing
efficiency. There is little doubt that biologicalprocesses will be continued as base treatments.
However, biological treatments cannot be applied tolarge molecules and are toxic to microorganisms
due to their resistance to biological processes.1)
Tannins are highly distributed in organic
compounds in piggery wastewater and in moleculesthat are too large for biodegradation. They have an
adverse affect on different organisms ranging fromtoxic effects on animals to growth inhibition of
microorganisms.2) Therefore, other processes areneeded to increase removal efficiency. Advanced
processes based on chemical oxidation may be asatisfactory option for biological treatment of nondegraded wastewater.
Many researchers have reported oxidation ofpoly-phenolic compounds using ultrasound, ozone
and a combination of these.3) A combined operationof sonolysis and ozonation shows synergistic effects
in contaminated wastewater. The mechanism of
combination may be summarized in two ways.4)
First, the physical effects of ultrasound can enhanceO3 diffusion so that the specific area of O3 bubbles
can be increased. Second, cavitation produced byultrasound can generate more OH radical
formations, and increase diffusion efficiency.5)
While reports have been presented on the effects ofusing ozonation to degrade tannins, they do notincludetheeffectsofultrasoundandultrasound/ozonation.
The effects of ultrasound, ozone and their
combination were therefore investigated in thisstudy. Three different results will be presented forthe effects of total organic carbon (TOC) and theconcentration of tannins.
------------------------------------------------------------

Tannin (molecular form: C76H52O46, molecularweight: 1701.23 g; minimum assay: 90.0%) was
purchased from Yakuri Pure Chemicals. All
samples were sonicated for 1 h in a bath-typesonicator (Flexonic, Mirae Ultrasonic Tech.) with170 kHz and 400W. Ozone was produced from pureoxygen (minimum purity 99.99%) using an ozone
generator (LAB 2B, Triogen), yielding 2 g h-1 O3. A
schematic diagram of the experimental set-up is
shown in Fig. 1. The experiments were carried out
in a 200 mL reactor which was initially filled with
500 mg l-1 synthetic tannins. The experimental
temperature was maintained at 25 ±3°c, using a
cooling water system.
All samples were filtered using a 0.45㎛
Whatman filter and were then analyzed. The
removal of organic carbons via mineralization wasmonitored by the Sievers 5310C Laboratory Total
Organic Carbon Analyzer (GE Analytical
Instruments, Inc.) equipped with a 900 Autosampler
System (GE Instruments). The concentration oftannins was measured by the standard methods. 6)

hyeong@korea.ac.kr

Sampling
O3 generator

Cooling water inlet

Gas outlet

Cooling water outlet

Transducer

Fig. 1 Schematic diagram of the experimental set-up

3. Results and Discussion

Experiments were performed with ozonation alone,ultrasound alone and the combined US/O3 system in

1.0

0.8

0.6

0.4

0.2

0.0
0

10

20

30

40

50

60

Time (min.)Fig. 3. TOC degradation for tannins with individualand combined schemes (0.100 L, 25 ± 3°c,
[C76H52O46] = 0.3 mM); ●, US only (170 kHz, 400W);▲, O3 only ( 1 g L-1);◆, US + O3)

Based on these experiments, sonolysis ontannins degradation and mineralization is quiet low
but when combined with ozonation, significant
synergistic effects are indicated.

1.0

0.8

C/Co

and H2O2 yields. Furthermore, the cavitationinduced ultrasound increased the specific area of O3
bubbles prior to an accelerated reaction.

TOCt/TOCoorder to investigate the synergistic effects. As
shown in Fig. 2, the synergistic action of O3 andultrasound degradation was presented during thefirst hour by 80 % as compared to the ozonationand sonolysis alone, which showed 60 % and 5 %,respectively. Ozonation alone was relatively more
effective than ultrasound for tannins reduction, but
the combination of the two processes showed asynergistic increase in the overall process rate. This
could indicate that the cavitation event acceleratesozonation effects. Therefore, despite there being
quite a low efficiency when ultrasound is usedalone, the effects of ultrasound show that when it iscombined with ozonation it is effective inaccelerating the reduction of tannins. This result
concurs with other works where poly-phenolic
compounds were degraded by US/O3, US and O3
alone.7)

0.6

0.4

0.2

0.0
0

10

20

30

40

50

60

Time (min.)Fig. 2. Comparison of individual and combined
schemes for tannins degradation ( 0.100 L, 25 ± 3°c,
[C76H52O46] = 0.3 mM); ●, US only (170 kHz, 400W);▲, O3 only ( 1 g L-1);◆, US + O3)

All of the total organic carbon samples weremonitored and the data is shown in Fig. 3. The
simultaneous application of ultrasound and ozone
resulted in significantly enhanced tannins
mineralization. The use of ultrasound alone ontannins resulted in a limiting mineralization ofalmost zero percent after 60 min. Similarly, ozone
alone could only reduce TOC by about 20%.
In contrast, when the combination processes
were applied, the extent of mineralization exceeded
35%. When sonicated solutions are bubbled with O3
gases, the thermal decomposition of O3 (g) in thecavitation bubbles leads to enhanced OH radical

Acknowledgment
This work was supported by the Korea Scienceand Engineering Foundation (KOSEF) grant fundedby the Korea government (MOST) (No. R01-2007000-20886-0)
References
1. Scalbert, A. : Phytochemistry 30 (1991) 3875.

2. Cui MC : MS thesis. (2007)
3. Saroj DP, Kurmar A., Bose P., Tare V. andDhopavkar V. : wat. Res. 39 (2005) 1921.
4. Ince NH, Tezcanli G. Belen R and Apikyan IG :Appl. Catal. B: environ. 29 (2000) 167.
5. Tezcanli GG and Ince NH : Ultrasonics 42 (2004)
603.
6. APHA, Standard Methods for the Examination of
Water and Wastewater, 20th ed., 1998.
7. Destaillats H, Colussi A. J., Joseph JM andMichael R. Hoffmann : J. Phys. Chem. A 104(2000) 8930.

3P6-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 403- 404
11-13 November, 2008

The Effect of Sonication on Chlorine Disinfectionin the Inactivation of E.coli
Hoang Lam Pham1, Hyunjun Kim1, Myunghee Lim1, Iordache Ioan2, Jeehyeong Khim1(1 Dep. of Civil, Environ. and Architec. Eng., Korea University; 2 Nat. Res. andDevelopment Inst. for Cryogenics and Isotopic Technologies, Romania)
1. Introduction
Chlorination has been widely used as a method
for water disinfection in terms of pathogen control.
However, it is found that chlorination can cause
potential problems for human health because of theformation of disinfection byproducts (DPBs) thatare considered to be carcinogenic for humans, suchas trihalomethanes (THMs) and haloacetic acids(HAAs), etc 3). DBPs produced in water are causedby the reaction between chlorine and organic
matters 2). Therefore, chlorine concentration must
be controlled in order to prevent the formation of
DPBs.
Ultrasonic irradiation has been recently
investigated for bacterial inactivation because it has
proven to be effective when sonicating alone aswell as when combining with other disinfection
methods such as UV, H2O2, O3, chlorine. In
chlorination, low frequency ultrasound showed
highly synergic effects in pretreatment4) and in asimultaneous
treatment
with
a
short
1)
sonicationtime.
The aim of this study is to investigate the effect ofultrasonic irradiation in chlorine disinfection at
different powers and irradiation times on thechlorine demand of the inactivation of E.coli.

2. Materials and methods
A NaOCl solution of 8% (JunSei, Japan) was used
to produce a chlorine solution of 0.6±0.02 mg/l as
free chlorine. The final free chlorine concentrations
were verified by the DPD colorimetric method.
E.coli suspension (KCTC 2441) was prepared bya 24h growth at 37oC in an incubator in a LB broth(Difco). Bacteria were prepared at the initialconcentration of 6x105 cells cm-3 for experiments.
Serial dilutions and standard plate counts were used-----------------------------------------------------------hyeong@korea.ac.kr

as the number of bacteria. Results were reported asa percentage of the surviving colony forming units
per milliliter (CFU cm-3).
In the case of chlorine alone, a 10 mL solution
including bacteria was added to a 190 ml freechlorine solution. The residual free chlorine wasthen measured using the DPD colorimetric method.
For the combination of chlorination and ultrasound,the solution including bacteria and free chlorine
was sonicated in a 20 kHz probe system (vibra-cell
750, Sonics &Materials, USA).

Fig. 1 Schematic system of ultrasound probe
The chlorine demand is calculated by thefollowing:
Chlorine demand (chlorine alone)= initial concentration – residual (1)Chlorine demand (Chlorine with ultrasound)= initial concentration – residual– chlorine loss in sonication(2)
The loss of chlorine due to sonication wasdetermined by the sonication of a free chlorine
solution without bacteria.

3. Results and discussion
Fig. 2 shows the chlorine demand of chlorination

alone and chlorination with sonication. The
ultrasonic power was 225W and irradiation timewas 2 min.

0.08

0.06

0.04

0.02

Chlorination alone
Chlorination with sonication
-4

0.00
-2
0

2

4

6

8

10

12

14

16

18

20

22

Time (min)Fig.2. Chlorine demand of chlorination alone andchlorination with sonication

0.10

The result shows that the chlorine demands in thecase of the combination are higher than those ofchlorination alone for all periods of monitoringtimes. However, the differences in chlorine demanddecreased as time increased. A higher chlorine
demand in the case of chlorination with sonication
indicated that inactivation of bacteria could be
improved by ultrasound due to microjet,
microstreaming and enhancement of mass transfer.
To evaluate the effect of sonication time in thecase of chlorination with sonication, 2 min and 5
min of sonication time were applied in thecondition of 225 W, as shown in Fig. 3.

Chlorine demand (mg/L)

-4

0.08

0.06

0.04

150 W
225 W
300 W

0.02

0.00
-2
0

2

4

6

8

10

12

14

16

18

20

22

Time (min)Fig. 4 Chlorine demand for different powers in thecondition of 2 min irradiation

Acknowledgments

0.10

-6

Chlorine demand (mg/L)

Chlorine demand (mg/L)

0.10

The chlorine demand of 5 min sonication was
lower than that of 2 min sonication, indicating thata longer time period of sonication (5 min) had an
adverse effect on chlorination. Duckhouse et al.
reported similar results and they explained that
excess sonication could result in the reagglomeration of dead cells, which could thenprotect the living cells from further disinfection.
Fig.4 shows the effect of irradiation power for thechlorine demand in the condition of 2 min
irradiation for the inactivation of E-coli. Chlorine
demand increased as ultrasonic power increased.
However, the case of the application of 300 W was
not significantly enhanced compared to that of 225
W. Therefore, 225 W might be the optimum input
power condition in this case.

This work was supported by the Korea Scienceand Engineering Foundation (KOSEF) grant fundedby the Korea government (MOST) (No.R01-2007000-20886-0)

0.08

0.06

Reference
0.04

2 min
5 min

0.02

0.00
-4
-2

0

2

4

6

8

10

12

14

16

18

20

22

Time (min)Fig. 3 Chlorine demand for 2 min and 5 min sonication

1. H. Duckhouse , T.J. Mason, S.S. Phull and J.P.
Lorimer : Ultrasonics Sonochemistry 11 (2004) 173.
2. M.S. Siddiqui, G.L. Amy and B.D. Murrhy :Water Res. 31 (1997), 3098.
3. S.W. Krasner, H.S. Weinberg, S.D. Richardson,
S.J. Pastor, R. Chinn, M.J. Sclimenti, G.D. Onstad
and A.D .Thruston : Environ. Sci. Technol. 40(2006), 7175.
4. T.Blume , U.Neis : Ultrasonics Sonochemistry 11(2004) 333–336.

3P6-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 405- 406
11-13 November, 2008

The Effects of Power Density and Irradiation Time for
Ultrasonic Inactivation of E. coli‡,1

Hyunjun Kim , Hoang Lam Pham1, Myunghee Lim1, Mingcan Cui1, David Elena2,†,
Jeehyeong Khim 1
1(Dep. of Civil, Environ. and Architec. Eng. Korea Univ .,Nat. Res. and Development Inst. for Cryogenics and Isotopic Technologies, Romania2)

1. Introduction
Chlorination is the most common disinfection
method, which utilizes chemicals such as chlorine
and its products (ex. NaOCl). This is because
chlorination is inexpensive and effective for theinactivation of bacteria and viruses. However, there
are a number of problems associated withchlorination, which include its reaction with
dissolved chemicals and the production of harmful
by-products such as trihalomethanes (THMs),
producing unpleasant odors etc. [1]. Because of
these problems, alternative methods such as
ozonation and ultraviolet irradiation have been
investigated and the application of ultrasound in
disinfection has recently been investigated by anumber of reserchers [1,2,3,4].
When ultrasound is irradiated in an aqueous
phase, cavitation bubbles are produced. The
collapse of the cavitation bubble produces localized
high pressure and temperature resulting in damage
to the bacterial cell wall, the deagglomeration ofbacterial clusters, and the generation of oxidants
such as OH radicals and hydrogen peroxide whichattack the chemical structure of the bacterial cellwall [2].
Many reserchers have reported on the influential
factors
affectingcavitation
bubblesandcombinations of other disinfection methods (ex.
chlorination, UV irradiation, ozonation) in water
and wastewater desinfection using ultrasound[1,3,4]. While these studies included the influenceof power density, there was a diffculty incomparing
high power density-short time irradiation with low
power density-long time irradiation in the efficiency
of disinfection.
-----------------------------------------------------------hyeong@korea.ac.kr

The aim of this study is to investigate theefficiency of inactivation for E. coli by changing
the power density and irradiation time at a constant
input energy.
2. Material and Experimental method
E. coli KCTC (2441) was used in this test andwas grown in a LB broth (Difco) which wassterilized by autoclaving. Prior to performing thedisinfection experiment, 20mL of LB medium was
inoculated and incubated at 37ºC for 24h. The broth
was then centrifuged at 4000rpm for 10min and theE. coli cells were separated from the broth andwashed twice with a phosphate buffered saline(PBS, pH 7.2).
To adjust the initial concentration of E. colisuspension at approximately 4-5×107 cells/ml, a
PBS solution was added to the E. coli suspension.
The volume of bacterial solution for the experimentwas 100ml.

Fig. 1 Schematic of experimental set-up

The
experimental
set-upis
depictedschematically in Fig. 1. A glass vessel was placed ina water bath. The water temperature was controlled

at 20~25ºC using ice packs during ultrasoundirradiation.
The ultrasound system (Vibra-cell 750, Sonics &Materials) was a horn-type and operated at aconstant frequency of 20kHz. All equipments wereplaced on a clean bench.
The ultrasound system was operated at different
powers and irradiation times in order to investigate
the relationship between power density andirradiation time interval for efficiency of
disinfection. Table 1 shows the variation of soundpower, power density and irradiation in theexperiment.
Serial dilution and the plate counting method
were used as the method of analysis. A
desoxycholate agar broth (Difco) was used in theplate counts.

The variations of input energy calculated bymultiplying the power-density and the irradiation
time were 1350, 2700, 4050, and 5400 J/mL. Fig. 3
shows the effect of input energy in the inactivationof E. coli.

Table 1 Variation of sound power, power density andirradiation time at 20kHz , volume 100ml

The result at 1350 J/mL was the same fordifferent total powers. As input energy increased,
the results at 225W and 300W were the same andtheir results were higher than at 150W. From thisresult, it is possible that, at a critical power, this
could be removed at certain bacterial concentrations.
Below the range, the same energy results inineffectiveness.

Total power (W)Power density (W/ml)
Irradiation time interval (min)

150
1.5
15

225
2.25
10

300
3.0
7.5

3. Results and Discussion

Fig. 2 shows the effect of total power indisinfection. When the total power was higher, theefficiency of inactivation was higher in the E. coli.
This result was similar to that obtained in previous
research [5]. However, the gap of removal between
the result at 225W and 300W was smaller than thatat 150W and 225W, because an increase ofvibrational amplitude occurs in the decoupling
between the vibrational tip and the bacterial
solution and the energy transfer decreases [6].

Fig. 2 Effect of ultrasonic input total power ininactivation of E. coli

Fig. 3 Effect of ultrasonic input energy in inactivation of
E. coliAcknowledgments
This work was supported by the Korea Scienceand Engineering Foundation (KOSEF) grant fundedby the Korea government (MOST) (No. R01 - 2007
- 000 - 20886-0)
References

1. H. Duckhouse, T. J. Mason, S. S. Phull and J. P.
Lorimer: Ultrason. Sonochem. 11 (2004) 173.
2. A. Antoniadis, I. Poulios, E. Nikolakaki, and D.
Mantzavinos: J. of Hazard. Mater. 146 (2007)
492.
3. E. Joyce, S. S. Phull, J. P. Lorimer, and T. J.
Mason: Ultrason. Sonochem. 10 (2003) 315.
4. T. Blume and U. Neis: Ultrason. Sonochem. 11(2004) 333.
5. K. Masaki, O. Ryota, S. K. Naomi, T. Kouhei and
Y. Toshikuni: Biotechnol. Prog. 21 (2005) 897.
6. I. Hua, R. H. Hochemer, and M. R. Hoffmann:
Environ. Sci. Techol. 29 (1995) 2790.

3P6-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 407- 408
11-13 November, 2008

Biodegradability Enhancement in Ultrasound-assisted
Oxidation for the Removal of Dye
Eunju Cho‡, Junghyun Lim, Mingcan Cui, Younggyu Son and Jeehyeong Khim
(Department of Civil, Environmental & Architectural Engineering, Korea University)
1.

Introduction

In industrial wastewater, dyes are almost nonbiodegradable because they consist of various highmolecules. It is therefore difficult to remove dyesby using aerobic treatment or short-term anaerobic
treatment [1]. In particular, reactive dyes are very
soluble in water, rendering it difficult to degrade
organic dye using a conventional absorption or
activated sludge process [2].
Sonochemical degradation is applied to theremoval of the organic pollutants in aqueous
solutions by the cavitation effect. Recently, acombination of ultrasound and advanced oxidation
processes (AOPs) was investigated for enhancing
removal rate. Among these processes the
combination of Fenton’s oxidation and ultrasoundhas an effective removal rate. This process has asynergy effect based on the reaction of ferrous ion
with sonochemically produced H2O2 and it wasreported to enhance the sonochemical degradation[3].
The main objective of this study is to analyze thefeasibility of decolorization and mineralization by
combining the sonochemical process with the
Fenton process.
2.

Materials and method

C.I. Reactive Black 5 (Remazol Black B; MW =991.8 g mol-1) was obtained from DyStar in 80-85%
purity. A hydrogen peroxide solution (34.5% w/w,
extra pure) and FeSO4·7H2O (extra pure) wereobtained from the Samchun Chemical Co.
The sonolysis equipment was a Flexonic (Mirae
Ultrasonic Tech.) with a frequency of 35 kHz and a
400 W energy input. A reactor volume was 100mL.
A specially designed ultrasonic machine ispresented Fig. 1. The temperature was fixed at 2025℃ during the ultrasound irradiation. Samples ofthe dye solution were taken out at 15 minuteintervals. All samples were filtrated using a Syring
filter (0.45 µm) from Whatman.
The UV-spectra of dye solution was measured
using a UV-spectrophotometer Specord 40 from
Analytik Jena. The maximum absorbancewavelength (λmax) of C.I. Reactive Black 5 could befound at 597 nm from the spectra.
-----------------------------------------------------------hyeong@korea.ac.kr

Accordingly, the concentration of the dye solution
in the reaction at different reaction times wasdetermined by measuring the absorption intensity at
λmax = 597 nm and from a calibration curve.
Total organic carbon (TOC) measurements ofsamples were determined with a Sievers 5310C
Laboratory TOC analyzer and a Sievers 900
Autosampler (GE).

Fig. 1 Experimental set up (a) reactor, (b) sonicator,(c) cooling water inlet, (d) cooling water outlet
The initial concentration of dye was 10~100 mg
L-1. The ratio of concentration between H2O2 andFeSO4 was one to four, and the concentration of
H2O2 was 120 mg L-1. Before the experiment,
FeSO4 was dissolved in a solution for 1 hour, andH2O2 was injected in a solution immediately prior to
the experiment. During the Fenton process, thesample was well mixed using a stirrer.
3.

Results and discussion

The degradation of C.I. Reactive Black 5 was
carried out using three different approaches under
the following conditions : (1) Sonochemical process,(2) Fenton process, (3) Sonochemical + Fenton
process. Fig.2 shows the decolorization observed of
all the processes according to reaction time. After
60min reaction in the Sonochemical process andFenton process, the removal of C.I. Reactive Black
5 amouted to 5% and 80%, respectively. When thereaction in the Sonochemical was combined with
the Fenton process, the C.I. Reactive Black 5 wasalmost removed within 15 min.
Lin et al. [4] studied the decoloration of acid dye
by Sonochemical combined with the Fenton process,and observed that the degradation efficiency wasincreased by more than only one process. Duringultrasonic irradiation, the shockwaves created bycavitation can accelerate the reaction time. Because
ultrasound in the combined process is utilized forthe cleaning of the ferrous iron surface. Therefore,
the process of ultrasonic cavitations results cleans
ferrous iron, and accordingly more reactant surface
area was formed for further surface reactions.
However, after 45 min, the removal efficiency ofacid dye did not increase. It is assumed that the
Fenton process rapidly reacts with H2O2 during thefirst reaction, while the reaction rate almostchanged after the first reaction because H2O2 was
slowly created by ultrasound. Therefore, thedegradation occurs at a slow speed.Our results also
show that after 15 min the removal rate of reactive
dye had not changed.

initial concentration. A lower initial concentrationof degradation rate is more rapid than a higher
initial concentration. S. Vajnhandl et al. [5] showedthat the apparent decolorization rates decreased
with an increase in the initial concentration.

Fig. 3 The mineralization of C.I. Reactive Black 5(■ : Fenton process, ◆ : Sonochemical + Fenton
process ) , reaction condition - H2O2 = 120mgL-1 ;H2O2:FeSO4 = 1:4 ; [dye]0 = 100mgL-1; frequency =35kHz; power = 400W

Fig. 2 Degradation of C.I. Reactive Black 5 (■ :Sonochemical process, ◆ : Fenton process, ▲ :Sonochemical + Fenton process), reaction condition- H2O2 = 120mgL-1 ; H2O2:FeSO4 = 1:4 ; [dye]0 =100mgL-1; frequency = 35kHz; power = 400W
The mineralization carried out of C.I. Reactive
Black 5 is shown in Fig. 3, where the Fenton
process and the Sonochemical process combinedwith the Fenton process are compared. Although
80% of decolorization was achieved after 1 h for
the Fenton process, the removal ratio of TOC was
almost 20%.
The minimal change of TOC is due to thepresence of imediates such as methanoate, nitrite,
oxalate. As a result, the organic carbon still
remained as intermediate [5]. In the case of the
combination process (Fenton+US) the removal ratioof TOC was 50% within 60min. This concurs withresults obtained by Inoue et al. [6]. Inoue et al. [6]used additives (Fe2SO4) to enhance the degradationof TOC. Therefore, the combination process of
Fenton and ultrasound can be used as an effective
degradation of reactive dyes and TOC.
The degradation rate of dye is dependent on the

Acknowledgments
This work was supported by the Korea Science andEngineering Foundation (KOSEF) grant funded by
the Korea government (MOST) (No. R01-2007000-20886-0)
References
1. A. Rehorek, M. Tauber, and G. Gübitz :Ultrasonics Sonochemistry 11 (2004) 177.
2. Lin S.H. and Peng C.F. : Environmental
Technology 16 (1995) 693
3. H. Zhang, Y. Zhang and D. Zhang : Color.
Technol. 123 (2006) 101.
4. J. Lin, X. Zhao, D. Liu, Z. Yu, Y. Zhang and H.
Xu : J. Hazard. Mater. 157 (2008) 541.
5. S. Vajnhandl and A. M. Le Marechal : J. Hazard.
Mater. 141 (2007) 329.
6. M. Inoue, Y. Masuda, F. Okada, A. Sakurai, I.
Takahashi and M. Sakakibara : Wat. Res. 42(2008) 1379.

3P6-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 409- 410
11-13 November, 2008

Physicochemical elucidation of cavitation bubble
interfacial region
キャビテーションバブル気液界面領域の物理化学的解明
Ben Nanzai‡, Kenji Okitsu, Norimichi Takenaka, Hiroshi Bandow(Osaka Prefecture University, Department of Engineering)‡

南齋勉 , 興津健二, 竹中規訓, 坂東博 (阪府大院工）1. Introduction
It is known that powerful ultrasonicirradiation in a liquid brings about the formation,
growth and collapse of micro gas bubbles. During
the collapse, local reaction zone of extremely highpressure (several hundred atmospheres) andtemperature (several thousand degrees) areproduced due to the quasi-adiabatic collapse1 while
the bulk liquid temperature hardly changes. This
process is known as acoustic cavitation bubbles. In
aqueous solutions especially, the reactive OH
radicals and hydrogen atoms2 are formed from thesonolysis of water vapor.
LAS tends to accumulate at the interface ofcavitation bubbles due to their amphiphilic property,
and do not evaporate into the cavitation bubble
because of their low volatility derived from anionicstate. Therefore, from the sonolysis of LAS, it isanticipated that the relation between cavitation
bubbles and LAS molecules, and the behavior of
LAS molecules toward the interface of bubbles canbe estimated.
In previous reports, the sonolysis ofsurfactant has examined, however, the degradation
rate behavior has not considered systematically yet.
Therefore in this study, the relationship between
sonochemical degradation rates of LASs and theinitial LAS concentration was investigatedsystematically.

was sonicated in a water bath, which wasmaintained at 20°C by a cold water circulation
system.
R

SO3－ Na+R : C8 H17sodium p-octylbenzenesulfonate (LAS C8)

C9 H19sodium p-nonylbenzenesulfonate (LAS C9)
C12 H25
sodium p-dodecylbenzenesulfonate (LAS C12)
Fig. 1 Structural formula of LAS Cn. “n” is carbon numberof the alkyl chain.

The concentration of each compound inaqueous solution was monitored by HPLC. The
initial rate of degradation (within 10 min) was
estimated on the basis of the average of several
experimental runs. Since it was reported that therate of sonolysis obey pseudo first-order kinetics,
the LASs concentrations as the sonication time wasapproximated by exponential function and theirderivative value at zero sonication time wasadopted as the degradation rate used for the analysisof the obtained data.

3. Results and Discussion
2. Experiment
Aqueous solutions of three anion surfactants,
sodium p- octylbenzenesulfonate (LAS C8), sodium
p- nonylbenzenesulfonate (LAS C9) and sodium pdodecylbenzenesulfonate (LAS C12) were adjusted
from 15 µM to 3000µM.
Ultrasound irradiation was carried out using a
65 mmø oscillator (Kaijo 4611type; MFG.
No.37G4) and an ultrasonic generator (Kaijo
TA-4021type; Lot. No.19G9, frequency; 200 kHz),
which was operated at 200 W. A 60 mL Ar-saturated
aqueous solution containing each LAS compound-------------------------------------------------------------nanzai@chem.osakafu-u.ac.jp

In Fig.2, the initial degradation rates of LASs
are plotted as a function of initial soluteconcentrations. At the concentration below 100 µM,
it can be also seen that the degradation rates of allcompounds increased linearly with increasing initialsolute concentration. This increase is due to theincreasing of surface excess of LASs molecules andit is indicated that LASs molecules transport rapidly
to the interface of cavitation bubbles.
At high concentration, the degradation rates
increased with increasing the initial concentration,and then they passed the peak at different
concentration and decreased. Moreover, thedegradation rate of LAS with the longer n-alkyl

chain turned downward at lower concentration.
That is, LASs with longer n-alkyl chain length has
the peak at lower initial LAS concentration andlower degradation rate.

15
6

LAS C810

3◇ LAS C8
□ LAS C9
○ LAS C12CMC (mM)

Degradation rate (µµ M min-1)

9sonochemical efficiency by isolating the freesurfactant monomers from gas/liquid interface ofthe cavitation bubbles. Thus, micelles could beconsidered a good “shelter” from direct
sonochemical effects.4 Hence, the degradation rate
decreased with increasing initial LAS concentration
over CMC because more micelles were formed at
the effective reaction zone.

LAS C9

5

0
0

1000

2000

3000

Initial concentration (µµM)
LAS C12Fig. 2 Relationship between the concentration of LASs
and their initial sonochemical degradation rate.

Here, it is necessary to consider what affectedon the initial LASs concentration and thedegradation rate at each peak. It is proposed thatmicelle was formed at effective reaction zone via
the accumulation onto the interfacial region. That is,
the LAS concentration of effective reaction zone
might to reach the CMC and this concentration
seemed to affect on the peaks of degradation rate.
For the verification of this assumption, therelationship between the degradation rate and CMCof each LAS should be considered. The CMC
values were estimated by electric conductivity
method because the literature data were varied fromtest to test. In this estimation, the concentration
with inflection point was defined as the CMC.3
Subsequently, the relationship between CMC andeach LAS degradation rate at the concentration ofpeak was shown in Fig. 3. The linear relation can beseen among these plots. These results seemed to be
indicated several meanings. In the each case, it wassuggested that the maximum degradation rates wererelated with the CMC value. That is, though it was
indicated that the accumulation ratios were almost
same when the initial bulk concentration of each
LAS was same, the maximum accumulation ratio
was derived from CMC. Here, in addition to above
description, one more phenomenon could besuggested as the reasons for the decrement ofdegradation rate in Fig. 2. The concentration ofeffective reaction zone was reached CMC andmicelle was formed. Destaillats et al. proposed thatmicelleformation
reducedtheapparent

0
2

4

6

8
-1

Degradation rate (µµM min )Fig. 3 Relationship between degradation rates which havepeaks in Fig. 2 and CMC of each LAS.

4. Conclusion
The initial degradation rate of each LASs hada peak respectively. It was suggested that thesepeaks had some relations with CMC of each LAS.
The linear relation between them was confirmed
and accumulation ratio was estimated as 5.5 times.
Acknowledgment
This work was funded by the Sasakawa Scientific
Research Grant from The Japan Science society.
References
1. W.B. McNamara III, Y.T. Didenko and K.S.
Suslick: J. Phys. Chem. B 107 (2003) 7303.
2. A.E. Alegria, Y. Lion, T. Kondo and P. Riesz: J.
Phys. Chem. 93 (1989) 4908.
3. M. Manabe, H. Kawamura, A. Yamashita and S.
Tokunaga: J. Colloid Interface Sci. 115 (1987)
147.
4. H. Destaillats, H.M. Hung, and M.R. Hoffmann
Environ. Sci. Technol. 34 (2000) 311.

3P6-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 411- 412
11-13 November, 2008

Sonochemical degradation of phenol and cyclohexanolin mixed solution
混合溶液中におけるフェノールとシクロヘキサノールの超音
波分解
Kenta Ishikawa‡, Ben Nanzai, Kenji Okitsu, Norimichi Takenaka, Hiroshi
Bandow(Osaka Prefecture Univ.)
石川健太‡，南齋勉，興津健二, 竹中規訓, 坂東博 （大阪府立大学）

Introduction
When the high intensity ultrasonic wave isirradiated to solution, micro bubbles which arecalled cavitation bubbles generate with hightemperature and high pressure. It is reported that thesonochemical reaction happens at the inside ofcavitation bubbles and their interface.
Here, the site where the sonochemical
reaction takes place is defined as “Effective
Reaction Zone” (Fig.1) [1]. LogP was found to be
the representative parameter for understanding thehydrophobic properties of compounds. It isreported that the larger the value of LogP of solute
becomes, the easier the molecules are gathered in
the cavitation bubble interface and thedecomposition speed grows [2].
In this work, The competing reaction ofphenol and cyclohexanol as which the value of
LogP was almost the same was considered.
Moreover, the radical scavenge abilities werecompared in the sonication for each single solutesystem of the phenol and cyclohexanol.
Cabitation bubble
high temperature and pressure
・OH
・OH
・OH

・OH

Effective
Effective reaction
reaction
Zone
Zone

・OH
・OH
・OH

Bulk solution
ambient temperature

Gas-liquid interface
high concentration of OH radicals

Fig. 1. Effective reaction zone where the sonochemical
reaction take place.

Experimental
Ultrasound irradiation was carried out using a
65 mmφ oscillator (Kaijo 4611type; MFG.
No.91F2) and an ultrasonic generator-----------------------------------------------------------kea0820@chem.osakafu-u.ac.jp(Kaijo TA-4021type; Lot. No.19G9, frequencuy;
200 kHz), which was operated at 200 W. A 60 mM
Ar-saturated aqueous solution containing phenol
and cyclohexanol was sonicated in a water bath,which was maintained at 20°C by a cold water
circulation system (TAITECCP-150R). Whensingle solute system of the phenol and cyclohexanol,
the concentration of each solution were preparedfrom 0 µM to 500 µM. In the case of mixed
solution, the concentration of phenol was prepared
to 100 µM, and the concentration of cyclohexanol
was prepared from 0 µM to 500 µM. Hydrogen
peroxide yields were measured by the KI method
using a Spectrophotometer (U-3300). The
concentration of phenol was monitored by ahigh-performance liquid chromatograph (HPLC :Shimadzu LC-20AT, SPD-20AV) with UV
detection at 222 nm using a ODS column with amobile phase of acetonitrile/water (40:60 v/v)
flowing at 0.3 mL min−1.
Results and Discussion
OH radicals are formed from water pyrolysis
in the collapsing hot bubbles (Reaction 1).
H2O → •OH + •H
(1)
The reaction between OH radicals which are
generated from Reaction 1 produce hydrogen
peroxide (Reaction 2)•OH + •OH → H2O2
(2)
During the sonochemical treatments of radical
scavenger in water, radical scavenger reacts withOH radical and Reaction 2 is inhibited.

To compare the radical scavenge abilities,
the amount of the hydrogen peroxide
generation was shown in Fig.2. It could be seenthat the radical scavenge ability of cyclohexanol
was higher than that of phenol.
The values of LogP are 1.46 for phenol, and1.23 for cyclohexanol. In addition, reaction rate
constants of OH radical with phenol are 6.6×109 L
mol−1 s−1 and with cyclohexnol is less than 6.6×109
L mol−1 s−1 (reaction rate constant of OH radicalwith cyclohexanol is expected from the value of
heptanol, 1-hexanol and 1-heptanol). Expecting

80
phenolcyclohexanol70

H2O2 (μM)

60
50
40
30
20

zone” was densely distributed more than 20 µM andthe molecules of phenol competed withcyclohexanol to react OH radicals in this range ofthe concentration. Thus, the molecules of phenol
were densely gathered in the “effective reactionzone” at low concentration. It was suggested thatthe electronic repulsion from the π electron ofphenol was effective at low concentration.
50
Amount of phenol degradation (μM)

from two values of LogP and reaction rate constantof OH radical, the radical scavenge abilities ofphenol should be higher than that of cyclohexanol.
It was considered that it was related to themolecular structure of phenol and cyclohexanol.
Phenol has the π electron and cyclohexanol has thesterically-bulky structure. Thus, for phenol, it wassuggested that electronic repulsion with the πelectron was caused when the phenol molecules
started to be gathered on the cavitation bubble
interface.

45
40
35
30
25
20
15
10
5
0
0

10
0
0

100
200
300
400
500
scavenger concentration (μM)

600

Fig.2. Changes in concentration of the sonochemicallyformed hydrogen peroxide in phenol andcyclohexanol aqueous solutions.

Surface tension was measured as an index of
the gathering easiness of gas-liquid interface. This
result showed that there was practically no change
in the surface tention of each compound comparedwith that of water at low concentration. On theother hand, the surface tension of cyclohexanol has
become much smaller than phenol as theconcentration of solution was high. From this result,
cyclohexanol molecule was gathered easily on theinterface compared with phenol and it wasconsidered that the π electron repulsion effect ofphenol was larger than the effect of thesterically-bulky structure of cyclohexanol. However,whether the solute was densely gathered in theinterface at the low concentration is not elucidated.
Phenol and cyclohexanol were sonicated in
the mixture solution. This result was shown in Fig.
3. It can be seen that the decomposed amount ofphenol hardly changed up to the concentration of
cyclohexanol was 20 µM but it decreased as theconcentration of cyclohexanol increased. From thisresult, it was considered that the “effective reaction

200
400
cyclohexanol (μM)

600

Fig. 3. Sonochemical degradation of phenol as afunction of cyclohexanol concentration.

Conclusions
The
radicalscavengeabilitiesofcyclohexanol was higher than that of phenol. It wassuggested that this results related to the electronic
repulsion from the π electron of phenol.
References[1] K. Okitsu, K. Iwasaki, Y. Yobiko, H.Bandow, R.
Nishimura and Y. Maeda : Ultrason. Sonochem.
12 (2005) 255.
[2] B. Nanzai, K.Okitsu, N. Takenaka, H. Bandow
and Y. Maeda : Ultrason. Sonochem. 15 (2008)
478.

3P6-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 413- 414
11-13 November, 2008

Sonolysis of dicarboxylic acids in aqueous solution
炭素数及び不飽和度の異なる各種ジカルボン酸水溶液の
超音波化学反応
Rei Moriya†, Yukio Naruke, Hisashi Tanaka, and Hisashi Harada (College Chemistry,
Grad. School, Meisei Univ.)守谷怜‡，成毛由紀夫，田中寿，原田久志（明星大院 理工）

1. Introduction
It is important for sonochemical process
to produce cavitation during sonic wave irradiation.
Acoustic cavitation leads to localize spots of hightemperatures and pressures. Thermal and radical
fields for chemical reaction are prepared inside andaround the cavitation. Different reaction paths are
considered at each reaction site. Volatile compounds
go into cavitation babbles. Non-volatile materials,
on the other hand, stay around the babbles. The
other day, we have already reported about chemical
reaction of volatile compound [1]. We have also
examined chemical reaction paths of dicarboxylic
acids around the cavitation area [2]. Those acids, asprobe compounds for reactions around bubbles, arenon-volatile and water-soluble. Furthermore,products are simple and easy detectable.
In this paper, we discussed the differenceof products when various carbon numbers ofreactants were prepared. We also try to examine thedifference in behavior between with and without
double bond.

ultrasonic generator at 25℃. It was placed in atemperature-controlled water bath (EYELA) all thetime. Almost all trials were carried out underirradiation of 200 kHz (Kaijo, 200W). Sonolysis
was also tried to perform at other frequencies.
Before sonication, pure argon gas (Ar) was passed
through the reactant solution in order to expel theair. Then the glass reactor was sealed when it wasfilled with Ar. Saturated gas in the solution plays animportant role in the sonochemical reaction. In
our cases, we supposed the solution was saturated
with Ar.
2.3. Analysis

2. Experimental

The amounts of gaseous products in thereactor were determined by using a gas
chromatograph (Shimadzu, GC8A). Liquid
products in the solution, on the other hand, weredetected by using a liquid chromatograph(Shimadzu, LC10A).
Hydrogen peroxide in the solution was
analyzed by means of a colorimetric technique(Nacalai Tesque, Titanium sulfate solution for
detection of hydrogen peroxide, and JASCO,
V530).

2.1. Materials (Reactants)

3. Results and discussion

Series of dicarboxylic acids were prepared.
Those are oxalic acid (HOOC-COOH), malonicacid(HOOC-(CH2)-COOH), succinic acid
(HOOC-(C2H4)-COOH), maleic acid (cis typeincluding double bond, HOOCHC:CHCOOH), andfumaric acid (trans type including double bond,
HOOCHC:CHCOOH). We used extra pure grade
reagents (Wako Pure Chemicals) without further
purification. Each acid was dissolved into water.
Concentration and volume of trial samples are 8-10
mM (mainly 8.62 mM) and 30-100 cm3 (mainly
100 cm3), respectively.

3.1. Decomposition of saturated materials
Evolved gas volume(μmol)

200

H2
CO
CO2

180
160
140
120
100
80
60
40
20
0
0

2.2. Sonochemical reaction
A Pyrex glass short-neck Kjeldahl flask (actual
volume approximately 300 cm3, mainly 296 cm3)
was used as a reactor. The glass reactor containing
the reactant solutions was sonicated using an-----------------------------------------------------------07m2016@chem.meisei-u.ac.jp

1

2

3

Irradiation time(h)

4

5

6

Fig.1 Sonolytical products in gas phase fromsuccinic acid solution at 25℃
Figure 1 shows gaseous reaction products
from succinic acid solution under 200kHz
ultrasound in an Ar atmosphere. Hydrogen (H2),carbon monoxide (CO) and carbon dioxide (CO2)
were produced. Similar products were obtained in
all reactant solutions in this our work. The rates of
production, of course, were different. Hydrocarbons
could not be detected. In the case of malonic acid, alittle amount of methane has detected after longtime irradiation. Thus production of anothercompounds will be expected. Products in liquid
phase will be examined in near future.
Although it is not clear in this figure, theproduction rate of CO2 decreased with irradiation
time. The production rate of CO, on the contrary,increased with irradiation time.
Reduction of CO2 during sonication wasconsidered [3], as indicated below equation.

CO2 + H2 (or 2H) → CO + H2O --- (1)In order to confirm the relation between
chemical reactivity and carbon number (carbon
chain length), the sum amount of CO and CO2
produced during sonication in each reactant
solution is shown in Fig. 3. Oxalic acid recorded thehighest reactivity. The order of reactivity was
inverse relation to the number of carbon in themolecule.
3.2. Deference of rates between saturated andunsaturated materials
In the case of dicarboxylic acids of carbon
number over 3, there are unsaturated same carbon
number acids. For example, in the case of 4-carbon
compounds, fumaric acid and maleic acid arecorresponding to succinic acid. Each of them isisomer.

3.5

30

Amount of product / μmol・(6h)‐13

CO/CO2

2.5
2
1.5
1
0.5
0
0

1

Fig.2

2
3
4
Irradiation time(h)520

Sum amount of CO and CO2(μmol)

100Figure 2 illustrates the ratio went up with
irradiation time. This figure also shows CO wasevolved even at the early stage of sonication.
Namely, we note that CO is produced not only the
reduction of CO2 but also the direct decompositionof reactant. Thus, the reaction rate has to be
estimated from total amount of carbon compounds.
Oxalic acidMalonic acid
Succinic acid

16

20

6

Time dependence of ratio of CO to CO2

18

Succinic acid
Fumaric acid

14

CO

CO2

(CO+CO2)/H2

Fig.4 Comparison of sonolytical rates between
saturated and unsaturated dicardoxylic acids
Figure 4 indicates the comparison of thesum amount of CO and CO2 produced after 6 hours
sonication between succinic acid and fumaric acid.
Because both compounds have different hydrogen
number, the ratios of carbon products (CO and CO2)
to H2 produced were also illustrated in this figure. It
is seen that unsaturated compound is more reactive
than saturated one. We will report the reactivity for
another unsaturated 4-carbon compound (maleicacid) in the presentation site.

12
10
8
6
4
2
0
0

0.5

1
1.5
Irradation time(h)2

Fig.3 Effect of length of carbon chain on
chemical reactivity

References
1. H, Harada, A. Yoneyama, Y. Ikeda and K. Yasui:
Proc., 10th Meeting of the European Society of
Sonochemistry. (2006) p.59.
2. Y. Naruke, H. Tanaka and H. Harada: Proc., 14th
Photocatalyst Symposium. (2007) p.94.
3. H. Harada: Ultasonics-Sonochemistry. 5 (1998)
73.

3P6-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 415- 416
11-13 November, 2008

Effect of Agitation Condition on Performance of
Sonochemical Reaction
超音波化学反応性能に及ぼす攪拌条件の影響
Keiji Yasuda†, Kazumasa Matsuura and Hirotoshi Horizoe (Facult. Eng., Nagoya
Univ.)
安田啓司‡，松浦一真，堀添浩俊（名古屋大 工）

1. Introduction

120

In order to apply sonochemical methods toon-site wastewater treatment, the enhancement ofsonochemical reaction is necessary. It has beenreported that the superposition of ultrasonicfields(1) or the liquid mixing(2) increased thesonochemical reaction rate. However, there are few
studies from the reactor engineering for theenhancement of sonochemical reaction.
In this study, for different ultrasonic fields,
the effect of agitation condition on performance ofsonochemical reaction are examined.

(4)

(2)
(5)

100

Upper

350

Middle
(3)

140
h

100

(3)

50

Lower

2. Experimental

3. Results and discussion

Fig. 2 shows the effect of electrical power to
one transducer on the I3- concentration for different
positions of transducers. For the single irradiation,
the I3- concentration by using bottom transducer is

Bottom(1)( Unit: mm)

50

Fig.1 Outline of experimental apparatus
×
＋
×
△
□
◇
▲
■
◆

0.025

0.020

3

C [mol/m ]Fig. 1 shows the outline of the experimental
apparatus. The reactor was made of transparent
acrylic resin. The dimensions were 120 mm inlength, 120 mm in width and 350 mm in height.
Four PZT ultrasonic transducers were attached at
the bottom, lower, middle and upper of the reactor.
The ultrasonic frequency was 486 kHz. The
effective electric power applied to one transducer
was changed from 0 to 50 W. The propeller (φ 60mm) or turbine (φ 75 mm) type of agitator was used.
The agitator was inserted from top of reactor. The
distance between reactor bottom and agitator was
140 mm. The revolution rate of agitator waschanged from 0 – 200 rpm.
The samples were potassium iodide (KI) andtetraphenylporphine tetrasulfonic acid (TPPS)
aqueous solution. The initial concentrations of KI
and TPPS were 0.1 mol/L and 3.3 μ mol/L,
respectively. The sample volume was 4.5 L. The
concentration of triiodide ion (I3-) produced after 30
min sonication or TPPS concentration after 60 min
soncation was measured by using ultraviolet andvisible spectrometer.

(1)Transducer(2)Reflection
Plate(3)Stirrer(4)Vessel(5)Sample

SingleSum

Dual

Bottom (B)Lower (L)
Middle (M)Upper (U)
B+L
B+M
B+U
B+L
B+M
B+U

KI
Without agitator

0.015

0.010

0.005

0
0

20

40

60

P [W]

Fig.2 Effect of electrical power to one transducer
on the I3- concentration for different
positions of transducers

1.4

1.2

TPPS
BottomPropellerr = 2000 rpm

1
20
30
40
50
P [W]
Fig.3 Effect of electrical power to transducer onratio of TPPS decomposition conversion withagitator
1.6
P = 50 W
Bottom1.4

X / X No agitator or C / C No agitator [-]

0

10

1.2
1
0.8

Key
◆
◇
●
○

0.6

Agitator type
Propeller
TurbineSample
TPPS
KI
TPPS
KI

0.4
0

1000
1500
2000
r [rpm]Fig.4 Effect of revolution rate on ratio of TPPS
decomposition conversion or I3- concentration
for single irradiation from bottom with agitator
1.6

X / X No agitator or C / C No agitator [-]lower than those by using lower, middle and uppertransducers. This is because the fountain at liquidsurface inhibits the formation of standing wave inreactor. In the cases of high electric input power totransducer, the I3- concentration for dual irradiation
is higher than the sum of I3- concentrations for
single irradiation. It is considered that the area ofsonochemical reaction fields increases by thesuperposition of ultrasonic fields. For the dual
irradiation at P = 50 W, the I3- concentration byusing upper transducer is higher than those by using
bottom and middle transducers. It is considered thatthe liquid surface is easy to form standing wave byusing bottom transducer.
Fig. 3 shows the effect of electrical power totransducer on ratio of TPPS decomposition
conversion with agitator. The ordinate indicates thedecomposition conversion ratio of with agitator towithout agitator. The ratio of TPPS decomposition
conversion increases with electrical power. It isconsidered that at high ultrasonic intensity, thestanding wave is difficult to break by agitation.
Fig. 4 shows the effect of revolution rate on
ratio of TPPS decomposition conversion or I3concentration for single irradiation from bottom
with agitator. In the case of propeller type agitator,
the ratios of TPPS decomposition conversion and I3concentration increase with revolution rate. The
ratio of TPPS decomposition conversion is higher
than that of I3- concentration. It is considered thatthe agitation enhances the supply of TPPS toreaction filed since TPPS concentration is much
lower than KI concentration. In case of turbine typeagitator, on the other hand, the ratio of I3concentration decreases with revolution rate. This isbecause the bottom of turbine type agitator, which
has flat plate, reflects ultrasound and the degree ofreflection decreases by revolution of agitator.
Fig. 5 shows the effect of revolution rate on
ratio of TPPS decomposition conversion or I3concentration for dual irradiation with agitator. The
data for irradiation from bottom are almost same as
those for dual irradiation. In the case of TPPS, theexcessive agitation decreases decomposition
conversion. This is because the area of standing
wave becomes small by liquid turbulence. In thecase of KI, on the other hand, the dependence of I3concentration on revolution rate is small. Fromthese results, it is obvious that the agitation iseffective for low concentration sample.

X /X No Agiator [-]

1.6

500

1.4
1.2
1
0.8

Key
◆
◇
●
○

0.6

Transducer
position
Lower
L+B

Sample
TPPS
KI
TPPS
KI

P = 50 W
Propeller

0.4

References
1. R. Feng et al: Ultrason. Sonochem., 9 (2002)
231.
2. K. Yasuda et al.: J. Chem. Eng. Jpn. 32 (1999)
347.

0

500

1000
1500
2000
r [rpm]Fig.5 Effect of revolution rate on ratio of TPPS
decomposition conversion or I3- concentration
for dual irradiation with agitator

3P6-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 417- 418
11-13 November, 2008

Effect of Hydrogen Peroxide and Frequency on
Sonochemical Degradation of Phenol
Myunghee Lim‡ , Younggyu Son, Mingcan Cui, Jeehyeong Khim† (Dep. of
Civil, Environ. and Architec. Eng. Korea Univ.)

1. Introduction
The chemical effects of ultrasound enhancechemical reactivity through cavitation. Sonicationof aqueous solutions produces the formation,
growth and collapse of cavitation bubbles. The
collapse of the cavitation bubble results in a
localized high temperature (5000 K) and pressure(1000 atm) [1].
The main reaction mechanisms are radical
reaction (·O, ·H, ·OH, etc.) and pyrolysis. Volatilecompounds were directly volatilized on the insideof the cavitation bubble and were decomposed byhigh temperature and pressure. However, nonvolatile compounds barely diffused into the bubble,
and were therefore indirectly degraded by radicals
in the bulk solution or interface of bubbles.
Phenol, a hazardous chemical in the priority
pollutant list [2], was studied for its sonochemicaldegradation. To enhance the degradation rate ofphenol, various attempts have been made for theapplication of high frequency ultrasound [3],combinations of oxidants/additives [3, 4, 5] andintegration with ultraviolet rays [1].
In this study, an investigation was carried out on
the effect of hydrogen peroxide and frequency on
the degradation of phenol and total organic carbon(TOC).
2. Experimental Procedures
The sonochemical reaction was carried out in a
300 mL pyrex bottle (the reactor total volume 500mL) containing the solution. The pyrex bottle
reactor was emerged in an acryl reactor, as shown in
Fig. 1. The reaction temperature was maintained at
16~18℃ by using a cooling water system. The
ultrasound of 35 kHz, 1 MHz, and 240 W wereapplied in a bath type ultrasonic system (Frexonic,
Mirae Ultrasonics Tech.).
-----------------------------------------------------------hyeong@korea.ac.kr

High-purity phenol (Samchun) was used and theinitial concentration was 0.05 mM. 0.0018 mM ofhydrogen peroxide (Samchun) was added to thephenol solution.

Fig. 1 Schematic of sonochemical reactor

1 mL of liquid was analyzed by the direct
photometric method (5530D, standard methods forthe examination of water and wastewater, 20thedition, APHA) every 5 min. Hydrogen peroxide
was detected by the iodometric method [6]. The
total organic carbon (TOC) concentration wasmeasured by a TOC analyzer (SEIVERS 5310C
laboratory analyzer, GE).
3. Result and discussion
The concentration change of phenol is shown in
Fig. 2. A more rapid degradation of phenol occurred
during sonolysis at 1 MHz than at 35 kHz. At ahigher frequency, the power of the cavitation effectdecreased. Therefore, the cavitation event occurring
at a low frequency is more violent and efficient on
the inside of the cavitation bubble.
However, at a high frequency the acoustic period
is shorter and the size of the cavitation bubble
decreases. Consequently, most of the formed
radicals have sufficient time to recombine.
Therefore, a high frequency results in a highhydrogen peroxide concentration in aqueous
solutions, which can cause higher degradation rates

0.00180.0015

H2O2 conc. (mM)of non-volatile compounds (ex. phenols) than at a
low frequency.
In addition to the hydrogen peroxide in phenol
solution, the concentration of phenol was decreased
above 90% within 30 min (Fig. 3 (a)). On the otherhands, in the case where only the ultrasoundprocess was applied, the same degradation rate ofphenol was obtained within 120 min (1 MHz, Fig.
2). Therefore, the addition of hydrogen peroxide
can enhance the degradation of phenol. This
concurs with other results previously obtained [7].

0.00120.00090.00060.00030.0000
0

5

10

15

20

25

30

Time (min)(b)
Fig. 3 Concentrations of phenol and hydrogen peroxidewith sonication time ((a) phenol with hydrogen peroxide,(b) hydrogen peroxide)

Phenol conc. (C/C0)

1.0

0.8

(● : 35 kHz, ◇ : 1 MHz)

0.6

Therefore, a high concentration of H2O2 or somecatalysts (Fe2SO4) and a combination of AOPs
(advanced oxidation processes) are required for the
degradation of TOC.

0.4

0.2

0.0
0

30

60

90

120

Time (min)Fig. 2 Concentrations of phenol with sonication time(● : 35 kHz, ◇ : 1 MHz)

Hydrogen peroxide was individually added twotimes (initially, and after 15min). As soon as it wasplaced in the hydrogen peroxide, the TOC
concentration also decreased. The hydrogen
peroxide concentration also directly decreased (Fig.
3 (b)). This result was the same for different
frequencies.
In previous research [7, 8], additives in phenols
solution (hydrogen peroxide and Fe2SO4) were used
to enhance the degradation of TOC.

1.0

Phenol conc. (C/C0)

0.8
0.6
0.4
0.2
0.0

0

5

10

15

Time (min)

(a)

20

25

30

Acknowledgements
This subject is supported by Ministry ofEnvironment, Republic of Korea as “The Ecotechnopia 21 project” (no. 061-081-042).
References
1. Y. Chen and P. Smirniotis : Ind. Eng. Chem. Res.
41 (2002) 5958.
2. USEPA, National Recommended Water Quality
Criteria (2006).
3. M. H. Entezari, C. Petrier and P. Devidal :Ultrasonics Sonochemistry 10 (2003) 103.
4. M. Kubo, K. Matsuoka, A. Takahashi, N.
shibasaki-Kitakawa and T. yonemoto :Ultrasonics Sonochemistry 12 (2005) 263.
5. C. Wu, X. Liu, D. We, J. Fan and L. Wang : Wat.
Res. 35 (2001) 3927.
6. M. A. Beckett and I. Hua : J. Phys. Chem. A. 105(2001) 3796.
7. J. Lin, C. Chang, J. Wu and Y. Ma : Wat. Sci.
Tech. 34 (1996) 41.
8. M. Inoue, Y. Masuda, F. Okada, A. Sakurai, I.
Takahashi and M. Sakakibara : Wat. Res. 42(2008) 1379.

3P6-20

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 419- 420
11-13 November, 2008

Effects of gas content in a liquid on the thresholdfor free radical production
液体中の含有気体が超音波照射下のフリーラジカル発生閾値におよぼす影響
Kengo Okada1†, Nobuki Kudo, Mariame A. Hassan2, Takashi Kondo2 andKatsuyuki Yamamoto1 (1 Graduate School of Information Science and Technology,
Hokkaido Univ.; 2 Univ. of Toyama)
岡田健吾 1，工藤信樹 1，ハッサン マリアム アリ 2, 近藤隆 2，山本克之 1（1 北大院 情報; 2 富山大 医）1. Introduction
Ultrasound contrast agents, which aresuspensions of microbubbles of several microns indiameter, have been utilized for noninvasive
ultrasound diagnostic imaging and therapy1).
Exposure to ultrasound increases the risk foradverse effects of production of free radicals suchas hydroxyl (OH) radicals. It is known that theefficiency of free radical production depends not
only on acoustic parameters such as pulse duration(PD) and duty ratio2) but also on non-acoustic
parameters such as degree of gas saturation andaddition of microbubbles3). However, thecontributions of dissolved gas and microbubbles tofree radical production are still unclear.
In this study, effects of gas contents on thethresholds of PD and pulse repetition frequencies(PRF) for free radical production were investigated.
The thresholds of PD were evaluated using four test
solutions with different gaseous conditions:
air-saturated and degassed solutions with andwithout microbubbles.

An air-saturated and a degassed solution wereprepared by leaving KI-starch solutions in bottles at
atmospheric pressure and at 40-mmHg pressure,respectively. Microbubbles of 20 µm in diameterwithshellsconsistingof
polyvinylidene
chloride-acrylonitryl
copolymer(F-30E,
Matsumoto Yushi-Seiyaku) were added to both the
air-saturated and degassed solutions at aconcentration of 1 mg/ml just before sonication.
3. Results and discussion
Figure 2 shows a comparison of the amountsof free radicals produced in the four test solutions
exposed to ultrasound of 5 ms in PD and 100 Hz in
PRF. Amounts of free radical produced in the
air-saturated test solutions were larger than those in
the degassed test solutions regardless of thepresence or absence of microbubbles. Addition of
microbubbles increased the amount of free radical
produced in the degassed test solution but had noeffect in the air-saturated test solution. This resultshows that dissolved gas has a dominant effect on
free radical production.

2. Materials and methods
The experimental system used in this study
consisted of a water bath filled with degassed waterand a flat-face ultrasound transducer immersed in
the bath with its radiating surface facing up (Figure1). A dish was placed on the transducer, and 3 ml ofa test solution was gently poured into the dish. The
test solution was exposed to 1-MHz ultrasound of
0.1 MPap-p in pressure amplitude for 5 minutes atvarious PDs and PRFs. The colorimetric assay ofliberated I2 from KI-starch solution4) was used for
detecting H2O2, which is produced by therecombination of two OH radicals. The change incolor of the solution caused by H2O2 was quantified
as absorbance at a wavelength of 555 nm. The
absorbance of a test solution directly correlates toamount of free radical production.
---------------------------------------------------------------------------okada@bme.ist.hokudai.ac.jp

Function generator
Amplifier

Ultrasoundtransducer

DishKI-starch solution

Water
bath

Degassed water
Fig. 1. Experimental setup used in the experiments.

1

Absorbance at 555 nm

0.7

P<0.05

0.6
0.5
0.4
0.3
0.2
0.1
0

w/ bubbles w/o bubbles
Air-saturated

w/ bubbles w/o bubbles
Degassed

Fig. 2. Comparison of the amounts of free
radicals produced in air-saturated and degassed
solutions with and without microbubbles. Barsand error bars show the mean ± S.D. (n=4).
0.45
0.40
0.35
0.30
0.25
0.20

PRF
100 Hz200 Hz500 Hz1000 Hz2000 Hz

0.15
0.10
0.05
0.00
0

0.2 0.4 0.6 0.81

1.2 1.4 1.6 1.8

Pulse duration (ms)2

2.2

Fig. 3. Relationship between PDs andamounts of free radicals produced in airsaturated test solution without microbubbles.
2.0

Pulse duration (ms)References
1. C. M. H. Newman and T. Bettinger: Gene Ther.
14 (2007) 465.
2. A. Henglein, R. Ulrich and J. Lilie: J. Am. Chem.
Soc. 111 (1989) 1974.
3. D. L. Miller and R. M. Thomas: Ultrasound Med.
Biol. 21 (1995) 1059.
4. T. Kondo and G. Yoshii: Ultrasound Med. Biol.
11 (1985) 113.

P<0.01

0.8

4. Conclusion
To understand the underlying concepts
required for the determination of thresholds for free
radical production, the effects of dissolved gas andmicrobubbles on the thresholds of PD and PRF
were investigated. Dissolved gas has a more
dominant effect than that of microbubbles on boththe amount of free radicals produced and thethreshold.
Acknowledgment
This work was partially supported by aGrant-in-Aid for Scientific Research, Japan Society
for the Promotion of Science and was conducted asa part of a project of the Research and Development
Committee Program of the Japan Society of
Ultrasonics in Medicine.

P<0.01

0.9

Absorbance at 555 nm

In order to determine the thresholds of PD
and PRF, we evaluated the relationship between PD
and amount of free radicals produced at various
PRFs. Figure 3 shows the results in the
air-saturated test solution without microbubbles.
The amount of free radicals produced increased
linearly with increase in PD at fixed PRF. The
threshold of PD at a certain PRF was determinedfrom the intersection of a least-squares regression
line (shown as a dashed line in the figure) with thex-axis. The threshold line for this solution for free
radical production was then obtained as a functionof PDs and PRFs.
The threshold lines for the other three test
solutions were obtained in the same way as that
described above. Figure 4 shows a summary of thethreshold lines for the four test solutions. All of thethreshold lines had the same trend: PD decreased
with increase in PRF. The lines for the degassed test
solutions had higher threshold PDs at all PRFs than
did those for the air-saturated test solutions
regardless of the presence or absence of
microbubbles. Microbubbles caused a decrease in
the threshold in degassed test solution but not cause
in the air-saturated test solution. These results showthat dissolved gas has a dominant effect also on thethresholds.

1.0
0.8
0.6
0.4
Degassed without bubbles

0.2

Degassed with bubbles
Air-saturated without bubbles
Air-saturated with bubbles

0.1
100

200

400

600

800 1000

Pulse repetition frequency (Hz)Fig. 4. Thresholds of PDs and PRFs for free
radical production in air-saturated and degassed
test solutions with and without microbubbles.

3P7a-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 421- 422
11-13 November, 2008

Improvement of Tissue Strain Uniformity
Elastogram by Compression Optimizing

and

加圧方法最適化による組織内歪み均一性の向上及び elastogramの改善
Shizuka Sato†, Takayuki Sato, Sayuki Aiura, Yasuaki Watanabe, Shigeyoshi Goka andHitoshi Sekimoto ( Tokyo Metropolitan Univ.)†

佐藤翔 ，佐藤隆幸，相浦紗雪，渡部泰明，五箇繁善，関本仁 （首都大理工）1. Introduction
A tissue-strain distribution by compressing
the model is reflected directly in an image oftissue-stifness distribution in Elastography. In thisstudy, we develop the simulation tool which
optimize the tissue-strain distribution using adamper and a concave compression board. We set
thickness of damper, Young’s modulus andcurvature radius of concave compression board asparameters and consider the strain flatness in lateral
direcion as optimizing index.

2.1 Compression with damper using a flat board
We calculated the strain flatness with andwithout damper, which is 50 kPa in Young’s
modulus and has 3 mm thickness in order toconfirm the effect of insertion of the damper. Figure.
2 shows ratio of the strain under the center line tothe strain under the left line and that is regarded asstrain flatness. It is desirable that strain ratio is
closed to 1, and Figure 2 shows that the strain ratio
is improved remarkable in the shallow region.

2. FEM simulation
It is assumed that when a model with a flat
surface is compressed, damper reduce the large
strain caused by the edge of compression board isreduced by using a damper, and as the result, thetissue strain uniformity is expected to improve inthe observed region. In this study, we calculate thestrain distribution of an object consisted of threelayers as shown in Figure 1 under the compression
using Finite Element Method (FEM).
(a)Fig. 1 Simulation model-----------------------------------------------------------shizuka@esys.eei.metro-u.ac.jp(b)Fig. 2 Strain ratio between center line and left line(a)No damper (b)With damper

2.2

Compression using a concave board

As the result shown in Figure 2, the strain
ratio is lower than 1 in the region from 3 to 15 mm
depth, regardless of the insertion the damper. To
improve such low strain ratio, we use thecompression board which has a concave surface.
The result shown in Figure 3 is conducted bychanging the curvature radii of 500, 1000, 1500 and2000 mm of the concave compression board, in
addition to the insertion of the damper (50kPa,
3mm in thickness). This result illustrates that thecurvature radii of 500, 1000, 1500 and 2000 mm
contribute in improving strain flatness.

stiff layer is described as a highly-correlated region
than the soft layer.

Fig. 4 Image of strain distribution

5.

Fig. 3 Strain ratio using a concave compression
board

3.

FDTD simulation
According to the strain distribution obtainedby FEM analysis, the wave motion analysis of thepre- and post-compression tissue based on FDTD
method was performed to produce an elasticity
image, which is necessary for screening of thecompression optimizing.
The wave motion analysis is also performedon the drawn in Figure 1. The scatterers wererandomly arranged in the tissue at the rate of 1%.
The tissue is given the 1% compression in the axial
direction, and the echo signals of the pre- and postcompression are collected.
4.

Cross correlation processing
Executing 1-dimentional cross correlation
process between the corresponding echo signallines of the pre- and post- compression, an elasticity
distribution image can be obtained.
For elasticity image, the stiffer region
generally leads the higher correlation value. Figure
4 shows the obtained image of elasticity distribution
drawn in a grayscale. The whiter region indicatesthe higher correlation value, namely, the harderregion. As shown in Figure 4, it is found that theConclusion
We tried to optimize the tissue compression
using FEM simulation in order to improve the strain
nonuniformity of compressed tissue which causes
degradation of elastogram. As the results, it ispossible to improve the strain flatness along thelateral direction by the insertion of the damper andusing the concave board in the numericalexperiments. In order to improve the quality ofsimulation image, FDTD method simulation shouldbe improved.
Reference
1. M.O'Donnell, et al., IEEE Trans. Ultrason.,Ferroelect., Freq.Contr. 44 (1997)1304-1319.

3P7a-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 423- 424
11-13 November, 2008

Optimization of Apodization Function For Lateral
Modulation
横方向変調の最適化
Chikayoshi Sumi†, Yuuichi Komiya and Shinya Uga(Facult. Sci. Tech. Eng., Sophia Univ.)

炭親良†，小宮勇一，宇賀真也 (上智大 理工)

1. Introduction
We have realized the beamformings [1-3] for
accurately
measuringtissueorblooddisplacement/velocity vectors or strain tensors [4]using multidimensional cross-spectrum phasegradient method (MCSPGM), and multidimensional
autocorrelation and Doppler methods (MAM and
MDM). The beamformings are realized by using thesteerings of the multiple beams and apodizations. In[1-4], we reported several lateral cosine modulation
methods (LCMMs) that use different apodization
functions in addition to the multidirectional
synthetic aperture method (MDSAM) and themultiple transmitting method (MTM). As shown,the coherent superimposition of the steered beams
performed in LCMM has a higher potential for
realizing a more accurate measurement of
displacement vector than the synthesizing of thedisplacement vector using the accurately measured
axial displacements performed in MDSAM and
MTM. However, in LMMs, MDSAM and MTM
can also be used to obtain plural steered beams. If
necessary, plural transducers are also used (forinstance, for heart). These modulations can also be
used for B-mode imaging [1-3].
For these beamformings, in [1,3], we also
reported more proper apodization functions thanthat using Gaussian functions we proposed
previously, i.e., those using parabolic functions andHanning windows. The uses of the proper functions
realize the echo data having wider lateral
bandwidths and higher signal-to-noise ratios(SNRs). Moreover, we also reported an
optimization method [1,2] for obtaining the best
apodization function in a least squares sense. Thatis, the best approximated designed point spreadfunction (PSF) can be obtained.
We have also started to report the research for thebest PSF. First, in order to gain the insight about theideal shape of the PSF, the accuracies of the 2D
displacement vector measurements were comparedby using simulated rf-echo data that have PSFs with-----------------------------------------------------------c-sumi@sophia.ac.jp

lateral envelopes, i.e., Gaussian function (GA),Hanning window (HA) and parabolic function (PA).
Next, for the three PSFs used, by calculating the
PSFs and spectra using a typical type transducer
model and the apodization functions respectively
obtained using the optimization method andFraunhofer approximation, we'll also compare theaccuracies of the realized PSFs.
2. Ideal shape of PSF
We simulate laterally modulated echo data using
the PSFs having lateral envelopes, i.e., GA, HA and
PA. For the three PSFs having a same energy, theorder of the full width half maximums (FWHMs) is,
PA > HA > GA, whereas that of the lengths of theirfoots is, GA > HA > PA [2,3]. The PSFs that have asame beamwidth are also used. For both cases, theaccuracies of the 2D displacement vector
measurements are evaluated. Rigid motions andstrains (0.1 to 4 percent) are respectively simulated.
The typical ultrasound (US) frequencies are used (1,3.5 and 5 MHz). The lateral modulation frequencies
are set at the same as those of US frequencies. The
SNRs of the simulated echo data range form 10 to
30 dB.
For LCMMs, the order of the measurement
accuracies was, PA > HA > GA. For only an axial
strain case, for instance, see Fig. 1, i.e., SDs ofmeasured lateral displacements when US frequency,
3.5 MHz; σ x (of 2D GA) = σ y = 0.4 mm;
window sizes used in MCSPGM, 1.6 × 1.6 or 3.2
× 3.2 mm; echo SNR, 20 dB. Similar results wereobtained for axial displacement measurements(omitted). For LCMM, a PSF having a wider
FWHM was ideal. Long foots are extra. Such a PSF
yields a high echo SNR and a large spectrum of thecenter frequency.
3. Accuracies of realized PSFs
Next, for the three PSFs used, the PSFs andspectra are calculated using Field II. For GA, thelateral SD σ y of 0.6 and 0.8 mm were used under
the conditions of US speed, 1,500 m/s; USfrequency, 3.5 MHz; modulation frequency (fy),1/ λ mm-1; and modulation depth, 30 mm. For thethree PSFs, Fraunhofer approximation was usedsuch that the corresponding apodization functions
that yielded the same intensity of a transmitted US
could be obtained. The transducer parameters usedwere of element size, λ ; height, 5.0 mm; and thespace between elements was 0.1 mm. The beam
pitch was 0.1 mm.
All the obtained apodization functions were able
to approximate the three PSFs. See Fig. 2, i.e., thePSFs obtained for GA and PA and Fig. 3(a), i.e., thelateral profile for PA ( σ y of 0.8 mm, and GA andHA omitted). For the respective three PSFs, thecorresponding same shapes of US pulses were used,although the respective shapes should be optimized
together with the apodization functions.
Furthermore, for the three PSFs, optimizations of
the apodization functions were performed on thebasis of a least squares estimation [2]. The
conjugate gradient method was used, in which therespective apodization functions obtained by
Fraunhofer approximation were used as the initial
estimates (specifically, only two main lobes wereused). See Fig. 4, i.e., the PSFs of the GA and PA
and Fig. 3(b), i.e., the lateral profile for PA. As
shown, the optimizations significantly increase thelateral bandwidths [see Fig. 3(a) vs 3(b)]. However,
the optimization used also made the foots of the
PSFs slightly longer.
4. Better PSF obtained by nonlinear optimization
Thus, we obtain the insights of the best PSF thatcan be obtained using all the insights about the ideal
PSF and the accuracy of the practical beamforming.
The foots of apodization function should be cut asshown in Fig. 5a [5]. The better optimization can berealized, for instance, by involving a nonlinear
manner, i.e., cutting procedure of the foots of theapodization function at each iteration. This allows
the decrease of the channels or the confine theeffective aperture. The obtained apodization
function and PSF are shown in Fig. 5b to 5d. The
better PSF than PA (i.e., the best PSF) will be
designed or depicted [2]. The described procedure
can also be used for the optimization of thetransmitted US pulse shape. Such obtained
beamforming parameters can also be used for thebest B-mode imaging.
References
1. C. Sumi: Jpn. J. Appl. Phys., 47(5B) (2008)
4137.
2. C. Sumi: IEEE 2007 Int Ultason symp, 1557.

3. C. Sumi: IEEE Trans UFFC (in press).
4. C. Sumi: IEEE Trans on UFFC 55 (2008) 24.
5. C. Sumi: 2008 Acost Soc Jpn Fall meeting.

Fig. 1. SDs of lateral displacements measured on
simulated rf-echo data.

(a)

(b)

Fig. 2. PSFs obtained using the apodization
functions obtained by Fraunhofer approximation(FA). (a) GA and (b) PA.

(a)

(b)

Fig. 3. For PA, lateral profiles of PSFs obtained by(a) FA and (b) Optimization.

(a)(b)
Fig. 4. PSFs obtained by optimization. (a) GA and(b) PA.

(a) Schematic of apodization. (b) Optimized for PA.

(c) PSF for PA (d) Lateral profile for PA
Fig. 5. Nonlinear optimization.

3P7a-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 425- 426
11-13 November, 2008

Lateral modulation and displacement vector measurement
using hyperbolic scan by virtual beam forming
仮想ビームでの双曲線走査による横方向変調と変位ベクトル
計測
Kengo Kondo1†, Makoto Yamakawa2 and Tsuyoshi Shiina3 (1 Grad. Sch. of Sys. and Inf.
Eng., Univ. of Tsukuba; 2Grad Sch. of Eng., Kyoto Univ. ; 3Grad Sch. of Med., Kyoto
Univ.)
近藤健悟 1‡，山川誠 2，椎名毅 3 （1 筑波大 シス情; 2 京都大 工; 3 京都大 医）1.

Introduction

Various methods measuring multidimensional
displacement have been developed. Generally theaccuracy of measured displacement vector is highin beam direction, while it is low in lateral direction
because the point spread function constituted by RFsignals represents acoustically-oscillated pattern inbeam direction but not in lateral direction. Lateralmodulation method was proposed by Jensen et. al.
[1] for blood flow measurement. The method
generates lateral ocsillating RF signal, whichenables us to attain high-accuracy measurement oflateral displacement. However, this modulation
method realizes the RF signal as designed below
center of aperture, consequently it causes distorted
RF far from center of aperture. The distorted RF
causes a loss of the linearity of point spreadfunction. We propose a method to solve thedistortion by designing a suitable beam scan path.
2.

Lateral Modulation Method

Lateral modulation method generates lateraloscillating waves by using specific apodization
function in linear scan. The function is inverse
Fourier transform of product of cosine function andrectangular [1] or Gaussian [2] window function, i.e.
two delta functions convoluted by sinc or Gaussianfunction. A lateral frequency of the modulated RF
depends on lateral positions of the two delta
function and a depth, thus the apodization function
is varied with the depth in order to keep a constantlateral frequency.
We propose a hyperbolic scan method inorder to improve the PSF. The hyperbolic scan isrealized continuously focus on a hyperbola usingsynthetic aperture beamforming approach. Lateralmodulation can be simplified as superposition of
two spherical waves, which are transmitted fromtwo point sources corresponding to peaks of
apodization. Phase difference between the sphericalwaves are equivalent on any points of a hyperbola
with foci the source of spherical waves, because a
hyperbola is the locus of points such that the
distances of a point from the foci differ from eachother by a constant amount. An apodization
function is superposition of two Gaussian functions
with peak points at one quarter from both ends ofthe aperture respectively, and is constant withdepth.
3.

Displacement Vector Measurement

We propose a 2D Combined Autocorrelation(2D-CA) method which can measure 2D
displacement vector. The method is an enhanced
method of Combined Autocorrelation (CA) Method[3], which has been proposed as a 1D displacement
measurement method with high accuracy andwide dynamic range for tissue elasticity imaging.
The 2D-CA method estimates displacement vector
as follows:1.

Calculate rough (wavelength perdisplacement by 2D template matching.

step)

2.

Separate lateral and axial oscillations of RF byheterodyning demodulation [4].

3.

Shift signal by rough displacement obtained bystep 1 to avoid aliasing, then measure accurate
lateral and axial phase shifts by autocorrelation(Doppler) method respectively.

4.

Transform phase shifts in axial direction along
hyperbola and lateral direction to displacement
components in x-y coordinate.

4.

Simulation Results

We evaluated the availability of the methodby simulation. The lateral modulation is applied to apoint scatterer model in order to observe point
spread function. Generated RFs by lateralmodulation are shown in Fig. 1 and 2. Below centerof aperture (lateral position x=0mm), 2D-RFs arecorrectly generated as designed in both method. On
the other hand, far from center of aperture (lateralposition x=20mm), generated RF is distorted inconventional lateral modulation method (linearscan), while it is not distorted as designed in our
proposed method (hyperbolic scan). The resultshows that the proposed method yields the same
PSF pattern at any points regardless of the lateralposition or the depth.

Fig. 1 Lateral modulated RF at depth 50mm, x=0mm

displacement vector. Beam scanning paths locatedon hyperbola make a uniform PSF pattern. The
validity of the hyperbolic scan method was shownby simulation. The effectiveness of 2D-CA methodwith hyperbolic scan was also shown by simulation
on displacement vector estimation. In the next stage,
we are going to verify the availability of proposed
method by phantom experiments.
References
1. J. A. Jensen and Peter Munk: IEEE Trans.
Ultrason., Ferroelect., Freq. Contr. 45 (1998)
837.
2. H. Liebgott, A.Basarab, D. Loizeau, J. E.
Wilhjelm. J. A. Jensen, P. Delachartre: Proc
IEEE Ultrason. Symp. (2006) 2168
3. T. Shiina, M. M. Doyley and J. C. Bamber: Proc.
IEEE Ultrason. Symp. (1996) 1331.
4. M. E. Anderson: Proc. IEEE Ultrason. Symp.
(2000) 1487.

Fig. 2 Lateral modulated RF at depth 50mm, x=20mm

Next, a model which expands uniformly inthe lateral direction, x, was used for estimating thedisplacement by the proposed 2D-CA method asshown in Fig. 3(a). Results of simulation forconventional and proposed lateral modulation are
shown in Fig. 3(b) and (c) respectively. Figure 3(b)shows that the farther from center of aperture (x=0),
the larger error of estimated value in conventional
method. It corresponds to the result of PSF
simulation. Figure 3(c) shows that proposed
method correctly estimated the lateral displacement
even in the area far from the center, consequently
the accurately measurable region is wider comparedwith the conventional method.
Expansion of cylindrical model as mimic left
ventricular was also simulated as Fig. 4 anddisplacement vector distribution was estimated by
the 2D-CA with hyperbolic scan. Figure 5 showsthat displacement vector components estimated by
the proposed hyperbolic scan method highly
coincides with the ideal image.
5.

Fig. 3 A model of lateral-direction deformation andestimated displacements

Fig. 4

Cylindrical simulation model

Conclusion

We proposed a new lateral modulation
method which indicates uniform PSF in whole
image. A uniform PSF is very useful for measuring

Fig. 5 Estimated displacement by 2D-CA methodwith hyperbolic scan

3P7a-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 427- 428
11-13 November, 2008

Experimental Evaluation of High-Speed 2D Motion Vector
Measurement by Combining Synthetic Aperture Array
Processing with Constrained Least Squares Method
配列型合成開口処理と制限付き最小二乗法を用いた高速二次元変位ベクトル推定精度の検討
Ryouta Yokoyama1‡, Shin-ichi Yagi1, Kiyoshi Tamura2 and Masakazu Sato3 (1 1Grad.
Sch. of Inf. Sci., Meisei Univ., 2 Alpka Co., Ltd., 3Microsonic Co., Ltd.)

横山亮太 1‡，八木晋一 1，田村清 2，佐藤正和 3（1 明星大院 情報; 2 アロカ（株）,3 マイクロソニック（株））

1. Introduction
Dynamic elastography could be a promissing
tool of diagnostic imaging for clinical tissue
characterization, in which various types of complex
tissue oriented structures and their high-speed
dynamics [1,2] are revealed by the advanced
algorithm of processing signals from ameasurement system, beyound conventional static
elastography.
Ultra-high speed ultrasonic imaging can be
maximally realized by a single trasmission ofpulsed ultrasonic field from a tansducer aperture
without any beam scanning by introducing
synthetic aperture (SA) array signal processing. In
order to develop ultra-high speed dynamic
elastography we adopted an integrated combinationof SA technology and alternate generations ofvirtual point sources controlled by exciting arrayedelements of the same transducer. This combination
successfully realized each successive dynamical
distribution of 2-dimensional motion vectors at
ultra-high frame rate from 2-dimensional echoframes which were saved in real-time across atissue phantom [3,4].
For the next step toward an accessible
ultra-high speed elastograpy the verification of
measured local phase change in accuracy andvariance has to be analyzed, which is required to
calculate local displacement vector components.
Thus, the spatio-temporal performance of
conventional cross-correlation
methodwascompared with the constrained least squares method[5] for SA reconstructed echo data at 4000 frames
per second from a tissue phantom where a transient
shear wave is propagating across the medium.
2. Measurement System
The experimental system setup of transducer
and tissue phantom to obtain 2-dimensional motion
vector distributions which reflect the traveling of-----------------------------------------------------------‡ e-mail:yoko@con.ei.meisei-u.ac.jp

transient shear wave caused by pulsed excitation ofa wideband electrodynamic transducer (Labworks
ET-132-203, DC-11kHz) are shown in Fig. 1.

Fig. 1 Experimental setup for external stress input
and alternate irradiations by two virtual point
sources A and B across a 1 % gelatin phantom
including 1 % fine starch powder.
The linear array transducer has 256 elementswith 0.25 mm lateral pitch and 13 mm elevational
width and 3.0 MHz center frequency with 2 MHz
bandwidth. The each element is controlled togenerate alternate virtual point sources which
realize local phase change estimate in different
directional evaluations through SA processing, andconnected to A-D converter (30 MHz, 12-bits) witha huge individual cache memory.
The SA processing with matched filtering iscarried out in spatial frequency domain for parallel
signal processing in practical stage by

Q(k x , k y ) = e− j ( k 2 − k u 2 X + k uY )S (k u , ω ) P * (ω ) ,where S(ku, ω) is 2-dimensional Fourier transformof received analytic echo signal s(u,t) on an arrayelement (X,Y+u) shifted from the array center(X,Y), which is scattered from distributed target
reflectivity q(x,y). P(ω) is a spectrum of transmitted
pulse from the point sources. The reconstructedcomplex echo frame p(x,y) with optimum
resolution is obtained by 2-dimensional inverse
Fourier transform of Q(kx,ky).
3. Estimate of Instantaneous Local Phase
ChangePrimarily the instantaneous local phasechange Δφ(x,y) between SA reconstructedsuccessive echo frames p1(x,y) and p2(x,y) was
evaluated by the following complex spatial
cross-correlation method.
Δφ ( x, y ) = tan −1Im{ p1* ( x, y ) p2 ( x, y )}∈R

Re{ p*x ( x, y ) p2 ( x, y )}∈R

Fig. 2 The comparison of local phase change
evaluations by conventional cross-correlation
method and constrained least square method withina frame interval (1 ms).

,

where〈 〉∈R denotes the spatial average around the
local point (x,y) corresponding to the point spreadfunction of SA processing system.
The next step is to confirm the previous
evaluation using 2-dimensional expansion of theconstrained least square method which was firstly
proposed by Kanai [5] for the ill-posed problem.
Im{ p1* ( x, y ) p2 ( x + δ x , y + δ y )}∈R ,Δφ ( x, y ) = tan −1
Re{ p *x ( x, y ) p2 ( x + δ x , y + δ y )}∈R

δx and δy are satisfied to minimize the constrained
least square error around the local point (x, y) in thefollowing equation.
2 | p1* ( x, y ) p2 ( x + δ x , y + δ y )|∈R ',α min (δ x , δ y ) = 1 −22| p x ( x , y ) | + | p2 ( x + δ x , y + δ y ) |∈R 'where〈 〉∈R’ indicates the spatial averaging taken
around local position (x,y) and (x+δx,y+δy).
4. Experimental Data
The estimated area is set around the system
origin of x-y coordinate, in which the center of thearray transducer is located at (X,Y)=(-50 mm,0mm). The evaluation data along the center axis(y=0) are shown in Fig. 2, where the selected
ranges of spatial averaging area R and R’ are +/-0.8mm(:x), +/-0.75 mm(:y) and +/-0.4 mm(:x), +/-0.75mm(:y) respectively. The maximized phase change
at the far right is representing the transient stress
input, within 1 ms of frame interval and the entirely
smoothed distribution of local phase change
Δφ(x,0) on the small background motions areobserved where each αmin was appeared almost at
the origin of the concave characteristics, as shownin Fig. 3.

Fig. 3 Typical distribution α(δx,δy) of constrained
least square errors in Fig. 2 shows the minimum atthe original positions of successive two echoframes.
5. Conclusion
The estimated instantaneous local phasechange across a tissue phantom by conventionalcross-correlation method showed no significant
difference from the data obtained the constrained
least square method. However the more precise
parameter changes for measurements seems to berequired to check the overall system performance.
Acknowledgment
This work was partly supported by Foundation for
Positive Health Promotion of Japan 2007.
References
1. H. Kanai: 2006 IEEE Ultrason. Sympo. Proc., pp.
760-763, 2006.
2. H. Kanai: IEEE Trans. Ultrason., Feroelect., Freq.
Contr., vol. 51, no. 11, pp. 1931-1942, 2005.
3. S. Yagi, A. Sanuga, K. Tamura and M. Sato: 2006
IEEE Ultrason. Synmo. Proc., pp.1205-1208,
2006.
4. S. Yagi, A. Sanuga, K. Tamura and M. Sato:
Acoustic Imaging vol. 29, pp.45-50, 2008.
5. H.Kanai, M. Sato, Y. Koiwa and N. Chubachi:
IEEE Trans. Ultrason., Ferroelct., Freq. Contr.,
vol. 43, no. 5, pp. 791-810, 1996.

3P7a-5

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 429- 430
11-13 November, 2008

Elastography Using Graph Cuts
グラフカットを用いた弾性イメージング
Naoto Akazawa†, Kan Okubo, Norio Tagawa (Tokyo Metropolitan Univ.,
Faculty of System Design)
赤澤直人‡ , 大久保寛 ，田川憲男（首都大 システムデザイン）

1. Introduction

3. Graph cuts (GC) algorithm

In recent years, graph cuts (GC) algorithm
has emerged as an increasingly useful tool for many
computer vision and image processing problems[1] .
This technique treats the segmentation problem as
an energy minimization problem; it optimizes theenergy function to solve the problem.
Meanwhile, elastography is examined as a
new application of ultrasound in medical diagnostic
imaging. This method utilizes signals observed indifferent situations (for example, with / without
additional static pressure ). Therefore, it is expectedthat we can apply GC algorithm to Elastography
successfully.
In this paper, we examined the effectivenessof elastography using GC algorithm. As a result, it
is clarified that we can obtain appropriate
displacement estimation at every region byelastography using GC.

GC is utilized to seek the label B thatminimizes the energy E (B ). Relation equations in
GC are given as(1)
E (B ) = E smooth (B )+ E data (B )(2)

E data (B ) = ! X (Bn )$ X #(Bn )n"N

E smooth (B ) =! #Potts(B , B )n(n , n +1)"Nn +1$!0 | Bn = Bn +1
Potts (Bn , Bn +1 ) = #!"1 | Bn % Bn +1

Fig. 1

Simulation modelFig. 2

Simulation dialog-----------------------------------------------------------† E-mail: naoto.akazawa@n-akazawa.org(4)! is smoothing parameter. Now, we use Potts
model and expansion move algorithm for GC.
The graph model of GC is shown in Fig. 3.
The initial allocation of the node is deriven as
displacement data B(t ).

2. Calculation models
Figure 1 shows the simulation model. We
assume the following conditions: three objects
having different elasticity are placed in front of asound source. Each object reflects an echo signal
which is different from each other in regard to theamplitude. We don’t consider propagation
parameters (dispersion or attenuation) of medium.
In this study, we set up that a center
frequency is 40 MHz and a band width is 4 MHz
for a transmitted FM chirp signal on the source. The
pulse width is 4 µs with the sampling rate of 500
MHz.
We prepare three ideal data for simulation
under the above conditions. The data are following
three signals: X (t ) , echo signal reflected fromobjects; X !(t ) , reflected echo signal with static
compression; A(t ) transmitted wave signal formatched filter. Total points of X (t ) is 16384, andX !(t ) has identical points. Figure 2 depicts
Schematic diagram of simulation. For X (t ) andX !(t ), white gaussian noise of 10% dynamic range
ratio is added respectively.

(3)

Fig. 3Graph model for graph cut

4. Calculated results and discussions
In Fig. 1, amplitude signals reflected fromeach object object1 is assumed as follows; 1.0 for
object1, 0.5 for object2 and 0.25 for object3. In
X (t ), the region of echo signal from object1 is from4000 to 8000, the region of object2 is from 8000 to
12000, and the region of object3 is from 12000 to
16384. Additionally, in X !(t ) , the regions ofobject1, object2 and object3 are respectively shiftedby 300 points, 400 points and 500 points, incontrast to X (t ).
Figure 4 illustrates a waveform of thereceived signals from the boundary of each medium.
Figure 5 shows detected signals of X (t ) andX !(t ) compressed by A(t ). Next, initial allocationof node cost B(t ) is plotted in Fig. 6 obtained bysimple correlation.
Figure 7 indicated the label data B
obtained using GC at ! =100. This result of thedisplacement has enough precision. Figs. 8 and 9
show the results at ! =10 and ! =200, respectively.

Fig. 4

Fig. 6

Fig. 7

Result at ! =100

Fig. 8Result at ! =10

Fig. 9Result at ! =200

Received echo signal

4.

Fig. 5

Sample data B(t ) for graph cut

Detected complession signal

Conclusions

This study has made a basic examination forelastography based on GC algorithm. Our
simulation confirm the feasibility of the proposed
technique. In near future, we intend to apply
elastography by harmonic components using graph
cut.
References
1. Hiroshi Ishikawa: IEEE Computer Society
Conference on Computer Vision and Pattern
Recognition (1999) p.1132.

3P7a-6

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 431- 432
11-13 November, 2008

Precise Tissue Elasticity Reconstruction Based on
Detection of Small Displacements
微小変位検出に基づく精細組織弾性イメージング
Sayuki Aiura, Takayuki Sato, Shizuka Sato, Yasuaki Watanabe and Hitoshi Sekimoto(Graduate School of Science and Engineering, Tokyo Metropolitan University)
相浦紗雪, 佐藤隆幸, 佐藤翔, 渡部泰明, 関本仁 （首都大学東京大学院 理工）

1. Introduction
While biopsy is the gold standard for the
diagnosis of malignant breast lesions, its invasive
procedures are painful for the patient. For
noninvasive diagnosis, the elasticity image fromultrasound echo data can be used to determine thetumor type with objective criteria. Thus the ultimate
goal of ultrasound imaging is to image the absoluteelasticity modulus precisely.
Most elastography methods primarily involve theimaging of strain fields in soft tissue. Elastograms
are created by comparing ultrasonic echo dataobtained before and after a slight compression of
the tissue. However, the quantitative modulus
images created by elastography are expected toprovide a more accurate method for thediscrimination of cancers from benign masses.
Because the strain images represent only relative
information within the sampled tissue, researchgroups have reported a variety of ways to create
modulus images [1-2]. We have also taken steps todevelopanabsolute
elasticity
modulusmeasurement system using the data from a
precision balance and radio frequency echo data in
Figure 1.
In this paper we propose an approach forreconstructing precise elasticity modulus images insimulation. Because breast tumors have various
shapes, hardnesses, and mobilities, the creation of
accurate images encounters two problems. First,
when the tissue is disturbed concentrated loads areapplied to the boundaries, particularly around theirregular form of an invasive lesion. This causes
stress concentration, and makes the normal tissue
around the boundaries appear stiffer than in
actuality [3]. Secondly, it is difficult to demonstrate
the boundaries between normal tissue and aninvasive lesion of simlar elasticity. Both problems
limit the effectiveness of elasticity modulus
imaging in its current state. Therefore as a first stepto improving the method, we introduce a detection
scheme that shows how the boundaries move withthe compression for mobility control and estimates
the small displacements around the boundaries.
-----------------------------------------------------------sabo@esys.eei.metro-u.ac.jp

lateral(x)axial(y)E=P/SP

Fig. 1 Measurement system

FEM

FDTD
SignalBeforeCompression

SignalBeforeCompression

Displacements
Data After
Compression

Fig. 2 Approach to the simulation

2. Methods
TheoryTo evaluate the credibiliy of the experiment using
the developed measurement system in Figure 1, we
observe the moment of boundaries in simulation by
two methods.
To generate ultrasound-like signals for thesimulation, the finite-difference time-domain
method (FDTD) is employed. The expressions for it
are obtained as:
P

n+

1
2

n−

−k

• n +1

ux

• n

• n



2∆t  11 
u y  i, j +  − u y  i, j −  
2 ∆y  
2
2 


1
1
n
n+

 1  •  1  1 2∆t  n + 2
 i + , j  = ux  i + , j  − P (i + 1, j ) − P 2 (i, j ) (2)
ρ
2
2
2
x
∆







• n +1uy

1(i, j ) = P 2 (i, j ) + k 2∆t u x  i + 1 , j  − u x  i − 1 , j  
2 ∆x   2 
 2 
(1)
n
n
•
•

1
n+

1  • n1  1 2∆t  n + 12 i, j +  = u y  i, j +  − P (i, j + 1) − P 2 (i, j ) (3)
2
2
2
y
ρ
∆ 






Here, P denotes the estimated sound pressure, ux theestimated lateral particle velocity, uy the estimatedaxial particle velocity, k volume elasticity, n thenumber of the time steps and i and j are the numberof points in the lateral and the axial directions
respectively.
Prospective displacements on the plane are
predicted with the finite element method (FEM)
using the expression below,1 − v
σ x 
v

E
 

σ
1
=
−
v
v
 y
τ  (1 + v )(1 − 2v )  00 xy  ∂u x




∂x
0

  ∂u

y

0

∂y

1
(1 − 2v )  ∂u ∂u y  (4)x2 ∂x + ∂y lateral(x)2axial(y)IndexMarkers1●
2.5[mm] 2.5[mm]1[mm]5[mm]where σ x and σ y are the axial and lateral stress,
τ xy is x-y shear stress, u x and u y are the axial
and lateral displacement, E is Young’s modulus, andv is Poisson’s ratio.
In the simulation, the postcompression FDTD
signals are adjusted according to the FEM
displacement data result. Figure 2 illustrates thisapproach to the simulation.
Simulation
Figure 3 shows a simulation model that consistsof a normal breast tissue model with 10mm(axial)
× 3.5mm(lateral) plane and a harder cubed
inclusion whose side is 5mm on the plane. Thistissue model is based on a measurement systemconstructed of a 192ch/10MHz transducer
generating a 10MHz frequency echo and a precisionbalance in Figure 1, and the corner of the inclusion
are derived from the whole plane for the following
the movement at the corner of the inclusion that
may cause stress concentration. The inclusion andadjacent tissues both have same thickness.
Young’s modulus of the inclusion is set to 60kPa
and of the surrounding tissue to 30kPa. Poisson’s
ratio is provided as 0.42 on the model. 1%
compression of the model height to the axial
direction is applied to the top of the model.
All elements are set to 0.05mm(a)×0.05mm(l)on the model for FEM. For FDTD eleven 10 MHz
acoustic waves are transmitted from the top of themodel to axial direction and the reflections arereceived at the transmitter just above the corner ofthe inclusion. The markers with extremly-hardstiffness are set in the model to stimulate theamplitude increment of the reflected waves. One
marker is located at 6 elements off the upper andright sides of the inclusion and the other is on. We
observe the movement of the markers to obtain thesmall displacement around the boundaries.

●

0.3[mm]10[mm]:30[kPa]
2.5[mm]3.5[mm]:60[kPa]
3.5[mm]Fig. 3 Simulation tissue model∆t=63nsec∆t=98nsec
Marker 1

4.5

Time[μsec]

5.5Marker 2

3.5

Time[μsec]

4.5

Fig. 4 Estimated waves in simulation

displacements in the experiment. The result shows
the possibility for imaging the precise elasticity
modulus around the boundaries between different
elastic properties of the tissue and under conditions
which give rise to irregular concentration.
4. Conclusion
In conclusion, the detection scheme described inthis article is confirmed to reconstruct elasticity
modulus images more precisely. We are now
developing an iterative finite element inverse
algorithm focusing on the boundaries with mesh
optimization to improve upon the elasticity imaging
result and preparing a phantom experiment where
the algorithm is used for imaging.

3. Results
In Fig. 4, the estimated waves at the receiver are
shown with the time delays indicating that themarkers move differently in different stiffnesses of
the tissue. The time difference between the delaysof the signals, 35 nsec, allows commerciallyavailable measurement systems, e.g. oscilloscopes,
to obtain tolerable echoes for detecting small

References
1. M. Yamakawa and T. Shiina: Jpn. J. Appl. Phys. 44 (2005) pp.
4567-4577
2. J. Li, Y. Cui, M. Kadour and J. A. Noble: IEEE Trans. UFFC 55(2008) pp. 319-326
3. E. E. Konofagou, T. Harrigan and J. Ohir: Ultrasonics 38 (2000) pp.
400-404

3P7a-7

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 433- 434
11-13 November, 2008

Development of Ultrasound Breast Imaging System
超音波乳腺画像の採取・表示システムの開発
Satoshi OZAWA1‡, Hokuma SAITO2,Masakazu SATO3, Hiroshi KITUNAI3, Takasuke
IRIE3, Masasumi YOSHIZAWA2, Kan OKUBO1, Norio TAGAWA1, Hiromu YOKOI4
and Nobuyuki HONDA5, (1 Facult. System Design , Tokyo Metropolitan Univ.;
2
Tokyo Metropolitan College; 3 Microsonic Co., Ltd.; 4 Yokoi Orthopedic Clinic;
5
Teramoto Memorial Hospital)
小沢智志 1‡，斎藤北茉 2，佐藤正和 3，橘内洋 3，入江喬介 3，吉沢昌純 2，大久保寛１，田川憲男１，
横井浩４，本田伸行５（1 首都大 システムデザイン; ２都立高専 ものつくり工; ３マイクロソニッ
ク 開発部; ４横井整形外科; ５寺元記念病院）

1. Introduction
To date, the ultrasound is paid to attention
as a method for diagnosis of cancer. The diagnosis
method of breast cancer that increases in recent
years includes mammography diagnosis andultrasound diagnosis. Mammography diagnosis uses
radiation to image the breast gland. Therefore,
frequent applications are not preferable. In thisstudy, ultrasound diagnosis with little harm forhuman body is taken up. The equipment to rotate aultrasonic probe mechanically and to acquire
images automatically has been developed recently.
Integrating this equipment, ultrasound imaging
system is examined, and developed. The proposedsystem is shown in Fig. 1.

Fig. 1 Ultrasound diagnostic equipment.

2. Image collection
In the imaging process, at first theultrasonic probe is rotated around a nipple on abreast to get the B-mode images in the inner part ofa breast, and next, the probe is rotated apart from anipple to image the outer part of a breast. An
example of the phantom image collected by thesystem is shown in Figs. 2 and 3.

Fig. 2 Example of B-mode image of phantom at innerpart.

Fig. 3 Example of B-mode image of phantom at outerpart.

3. Image processing for C-mode imaging
The cross-sectional B-mode image of awhole breast should be composed of the four
B-mode images already collected like Figs. 2 and 3
and forming a line. Actually, after selecting the four
images from the all collected images, theoverlapped regions in the each image are cut down,
and these are combined like Figs. 4 and 5.

To generate C-mode images, the voxel
image representation is adopted, and thethree-dimensional image is generated by inserting
the above mentioned cross-sectional images into thevoxel data region. The C-mode images are
generated by picking out the values of the voxels
positioned at the desired depth from the breast
surface. The examples are shown in Figs. 6 and 7.

The breast cancer

4. Discussions and conclusions
From the phantom images shown in Figs.
5 and 7, it can be confirmed that the proposed
imaging system has no geometric distortion.
Additionally, from the actual breast images shownin Figs. 4 and 6, it is obvious that this system is
effective for examination of breast cancer. In Fig. 6,
the position of the cancer is easy to be known.
In this study, we generate thecross-sectional images by confirming the optimallayout of the four images by eyes. As a future work,
including the image selection for generating thecross-sectional images, we construct the algorithm
by which all processing is done automatically basedon the pattern recognition strategy.

Fig.6 Example of C-Mode image of breast.

The breast cancer

Fig.7 Example of C-Mode image of phantom.
Fig.4 Example of cross-sectional image of breast.

References
1. T. Irie, H. Asaba, J. Anzai, H. Yokoi, and N.
Honda: Jpn. Soc. of Ultrasonics in Medicine 75(2002) S443.
2. N. Honda, H. Yokoi, T. Irie, and J. Anzai: Jpn.
Soc. of Ultrasonics in Medicine 79 (2006)
S214.
3. H. Yokoi, et al.: Jpn. Soc. of Ultrasonics in
Medicine 42 (1983) 627-628.
Fig.5 Example of cross-sectional image of phantom.

3P7a-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 435- 436
11-13 November, 2008

Evaluation of Preprocessing Operations for the Extraction of Fine Blood Vessels from
Ultrasound Images
超音波画像における細径血管抽出のための前処理手法の評価
Yasuaki Osawa, Masayasu Ito(Tokyo Denki Univ., Grad. School of Science. and Tech.)
大澤康明, 伊東正安（東京電機大学・理工）

1. Introduction
This paper is concerned with an image processing
technique, which extracts fine blood vessels froman ultrasound image as accurate as possible using
the noninvasive imaging system developed
before(1).
It is not difficult to detect a large blood vessel inan ultrasound image, since the brightness or theecho level of the blood vessel can be differentiatedeasily from that of neighbor tissues. On the other
hand, the small blood vessels show little differencein brightness from the neighbors. Besides, theircontours are not clear due to the speckle noise andthus preprocessing is essential to our purpose. So
far various smoothing and enhance methods havebeen proposed elsewhere. We examined an adaptive
morphological operation in image processing andfound that it can smooth and enhance the image at
the same time (2).
There exist many types of morphologicaloperations applied to the ultrasound image
preprocessing. They use different types ofstructuring elements. Typical structuring element isof a constant type and the others are of morefunctional ones. We tried a morphological operationof fuzzy type and adaptive ones of two different
structuring elements; triangular type and Gaussian
type. In this paper, we compare the new adaptive
morphological operation with the conventional ones
developed before and we will evaluate them. We
use the post processing techniques for extracting thecontour of fine blood vessels reported before(1).
Ultrasound images are accessed from the developed
non-invasive imaging and diagnostic system for
ultra fine blood vessels (3). It scans the region of--------------------------------------------------------------------------------07smj03@j.dendai.ac.jp ito@re.ccs.dendai.ac.jp

1[cm]×1[cm]×3[cm] using 30MHz transducer and128 successive cross sectional images are stored forprocessing.
2. Preprocessing
We already reported that morphologicaloperations are less affected by image quality andequipment, when the introduced structuring element
is dependent on the local image. In this research,
the following four filters are used. The first andsecond ones are adaptive morphological filters withdifferent structuring elements: triangular andGaussian type. The third is a fuzzy morphologicalfilter, which uses the fuzzy logic. The fourth is anormal morphological filter. Now closing andopening morphological operations result insuccessive 128 smoothed cross sectional images
with enhanced edges. The size and appropriate
parameters of the structural element of thesemorphological operations were decided by anevaluation function called separability.
3. Comparison of morphological operations
Here we introduced four evaluation indices;
separability, gradient, brightness difference between
the inner and outer regions, and blood vessel
extraction rate. Table.1 shows evaluated values
averaged around the extracted contours of relatively
large blood vessels after each of the four operations
is executed in the preprocessing. Separability is
calculated from the inner and interclass variances inthe spatial image of cylindrical region (radius 7
pixels, length 7 pixels). Strip of 3 by 7 pixels is
given to the evaluation region for gradient andbrightness difference,. Blood vessel extraction rateis the percent of the number of contour-extracted

frames to the total processed frames. Note here that
all the other indices are obtained from the extracted
contours. Similarly, we evaluated the extracted
small blood vessels as shown in Table 2.
Fig. 1 shows how the original noisy ultrasoundimage is smoothed and enhanced by the
preprocessing methods. Here only the profile of thewhite line in the blood vessel (Fig. 2) is shown forreference. Fig. 3 shows a 3D view of the extracted
blood vessels using Gaussian type adaptive
morphological operation.
Separability
Gradient
Brightness
difference
Blood vessel
extraction
rate

normal adaptive fuzzy Gauss
0.713
0.713 0.712 0.713
7.921
7.981 7.994 7.914
36.19

36.92 35.98

37.14

0.68

0.914 0.766

0.961

Table.1 Evaluated indices of four filters applied to large
blood vessel

Separability
Gradient
Brightness
difference

normal adaptive fuzzy Gauss
0.691
0.683 0.686 0.695
8.332
8.306 8.67 8.444
42.51

38.38 43.22

42.92

Table.2 Evaluated indices of four filters applied to small bloodvesselLine Histgram(i=270～479 & j=230)

100

original
morph
adapt
fuzzy
gauss

80

brightness

60

40

20

0
1

10 19 28 37 46 55 64 73 82 91 100 109 118 127 136 145 154 163 172 181 190 199 208
i coordinates

Fig 1 Profiles of the processed images

Fig.2

Preprocessed
ultrasound image

Fig.3

3D image of an
extracted blood vessel

4. Conclusion
From Table 1, we can conclude that the adaptive
morphological operation is a very usefulpreprocessing tool for image segmentation such as
contour extraction purpose. Little difference isobserved among the evaluation indices of the four
methods, when the contour extraction succeeds. The
structuring element of Gaussian type gives more
moderate smoothing and enhancement effect to thenoisy ultrasound image than the others. We observethat it becomes easy for the artifact due to theacoustic shadow to be removed in the postprocessing stage. We can say at this stage that theGaussian adaptive morphological operation issuperior to the others.
In the future we will analyze the function ofvariousadaptive
structuring
elements
mathematically and find a total evaluation function
from preprocessing to post processing.
Acknowledgment
This work was supported in part by a grant from the TDU
Frontier R & D Center and in part by the Regional Industry
Revitalization Project, Bureau of Economy, Trade and Industry.

References
1. Masayasu Ito, Yuzuru Saito, Yasuaki Osawa:
Evaluation of Preprocessing Operations for the
Extraction of Fine Blood Vessels from UltrasoundImages, Proceeding of Symposium on UltrasonicElectronics,
Vol.28,(2007),
pp.393-394,14-16
November, 2007.
2. M.Tsubai, M.Ito:Control of Variable Structuring
Element on Adaptive Mathematical Morphology for
Boundary Enhancement of Ultrasound Images,
Trans. Information and System, Vol.86-D-II,
NO.6,pp.895-907, 2003.
3. M. Ito, A. Yamada, K. Kato,K. Kobayashi,N.
Kuroshima,” Development of ultrasound imaging
and diagnostic system for fine blood vessel
structure., Proc. of 11th Congress of WFUMB,
Ultrasound in medicine and biology, 32,5S,278,
May,(2006)

3P7a-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 437- 438
11-13 November, 2008

Visualization of intersection points of motion vectors
in left ventricle by processing successive echograms!.+1 

,

*

(

Rui Takahashi‡, Kohji Masuda, Takashi Yoshinaga, Hirotaka Matsuura and Shun Uchibori( Graduate School of BASE, Tokyo Univ. of Agri. & Tech. )3&/‡6%-"6'6$)62 4#

1. Introduction
Now heart disease is the 2nd most common
cause of death in Japan. To find and diagnose heartdisease as possible as early, echography(ultrasonography) is indispensable equipment in
cardiovascular diagnosis due to its noninvasiveness,real-time observation and ease of carry. On theother hand, examination with echography greatly
depends on the expertise and experience of an
operator because of its blurriness and low spatial
resolution.
Comparigwith
otherorgans,echocardiogram (echogram of heart) includes
motion information more than the construction.
Thus the recognition software[1,2] in motion
pattern of heart on echocardiogram may help for aquatitative diagnosis independent to the operator.
Considering the short-axis view of heart,which extracts the plane perpendicular to the axis of
the artery, a normal ventricular wall expands andcontracts concentrically on echogram. To evaluate
the synchronicity of motion in the heart, the tissue
doppler imaging (TDI) technique is available andalready integrated with echography. However,
because the TDI has anisotropy in motion detection,
it is not suitable for comprehensive evaluation of
motion function. Therefore, we have developed asoftware to recognize the synchronous motion ofheart by calculating intersection points between the
instantaneous velocities of ventricular wall derived
from optical flow method[3].

0 BASE5

Defining the area which is a-th in the x
direction and b-th in the y direction is defined as Aab,the area velocity of Aab is calculated by averaging
all the vectors inside the area. Here we established = 15 pixel and P = Q = 30(0 < a < P, 0 < b < Q).

Fig.1 Division of the echogram into small areas andcalculation of the area velocity.

Because the shape of left ventricle in anormal heart reveals circle, prolongations of motion
vectors in the area velocities concentrate in thecenter of the left ventricle if it contracts
concentrically. And if there is local malfunction
caused by the disease as myocardial infarction,
prolongations of vectors make their intersections
dispersedly. Thus we aimed to reveal theintersection points which are derived from motion
vectors in the area velocities to evaluate thecomprehensive motion function of the heart.

2. Method
The video stream of echocardiogram was
captured by 8bit and 30fps by using the digitalechography (Toshiba AplioXV). Then the motion
vectors between frames were calculated by opticalflow method (time interval 33ms), where brightness
is more than the threshold. Next the x-y coordinate
system was applied to divide it into small squareareas which side is  pixel as shown in Fig.1.
-----------------------------------------------------------masuda_k@cc.tuat.ac.jp

Fig.2 Definition of the intersection point.

Fig.2 shows the definition of the intersection
point Kabcd which is created by the vector Vab of thearea Aab and the vector Vcd of the area Acd. The
coordinates of intersection points are calculated by
all of the combination between different two motion
vectors. Here to reduce calculation time, the motion
vectors are prolonged to the positive direction in thesystolic phase as shown in Fig.3 (a). On the other
hand, in the diastolic phase, the motion vectors areprolonged to the negative direction by recognizing
the motion phase from the electrocardiography(ECG). Then the instantaneous distribution of theintersection points is obtained as Fig.3 (b).

Fig.4 The distribution of the intersection index in MI
patient (70y.o., M) and its gravity point.

3.Results(a) The area velocities with their prolongations.

We have compared the distribution of theintersection index through every frame amongnormal subjects and heart disease patients. Fig.5
shows the trajectory of the gravity point of theintersection index during a heartbeat. The
fluctuation of the gravity point in the heart disease
patients is easily distinguished from the normal
subjects. In the normal hearts the gravity points
concentrate in a small region.

(b) Distribution of the intersection points.
Fig.3 Elucidation of the intersection points.

Moreover, because there is no quantitative
information in the distribution, the weight
coefficient is calculated to cumulate the frequency
in each pixel according to the magnitude of thevectors. In the intersection point Kabcd (0 < a,c < P
and 0 < b,d < Q), the weight coefficient Wabcd isdefined as the summation of the absolute values andmemorized as the arrangement (Kabcd, Wabcd). Thenthe weight coefficient in each pixel is summarized
and newly defined as W(x,y). However, since W(x,y)
is proportion to the number of the motion vectors, it
should be normalized by the number of the
maximum intersection points. Thus dividing W(x,y)
by N(N-1)/2, where N is the total number of thevectors, the quotient is finally defined as I(x,y),
which is named as the intersection index. Fig.4
shows the distribution of intersection index, whereI(x,y) > 1.25, in the myocardial infarction patient in
the systolic phase. Because of the asynchrony in theventricle motion, the shape of I(x,y) was distorted.

Fig.5 Trajectories of the gravity point during heartbeat in
two normal subjects and two heart disease patients.

4.Conclusions
We developed a new method to visualize thesynchronicity of motion in the heart by introducing
the intersection index. We are going to enhance theaccuracy of this method for quantitative evaluation.
References
1. G.E.Mailloux, et al, IEEE Trans. Med. Imaging,vol.8, no.2, pp.143-153, 1989.
2. T.S.Denney, Jr. and J.L.Price, IEEE Trans. on
Image Processing, vol.3, no.2, pp178-191, 1994.
3. K.Althoff, et al, IEEE Computers in Cardiology,
Vol 27, 2000.

3P7a-10

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 439- 440
11-13 November, 2008

Application of independent component analysis tospeckle reduction in liver echo image
肝エコー画像におけるスペックルリダクションへの独立成分解析の適用
Tadashi Yamaguchi1†, Hiroki Suyari2 (1 Research Center for Frontier Medical
Engineering, Chiba Univ.; 2Grad.Sc. of Advanced Integration Science, Chiba Univ.)
山口匡 1‡，須鎗弘樹 2 （1 千葉大 CFME; 2 千葉大 融合科学）

1. Introduction

fibersnecrotic tissue( or normal tissues )The speckle reduction method that doesn't
depend on the depth attenuation etc. is requested in
medical ultrasonics field.
In this research, it is examined to separate aspeckle and other signals by using independent
component analysis (ICA) for information observedby using ultrasonic diagnostic equipment. Subject
disease of this research is the liver fibrosis. Targets
are normal livers (in vivo) and fibrotic livers (invivo and in vitro). We analyze the relationshipbetween the characteristic of the signal thatobserved by US equipment and the result of
separation by ICA.
2. Basics of application of ICA to ultrasonicimage-----------------------------------------------------------yamaguchi@faculty.chiba-u.jp

signal element of normal tissue( speckle noise )Probability density

ICA is already applied in medical field suchas brain wave analysis with multi channel,
segmentation of brain function in f-MRI and color
component separation in optical measurement ofskin although the relation between the processing
result and phenomena is indistinct in either
measurement. In order to apply ICA to an ultrasonicimage, it is necessary to examine some causes ofgenerating and independency of echo signals. The
most fundamental feature of the ultrasonic image ofliver is a speckle. Speckle is the result ofinterference with reflected wave from a lot of
scatterers, and it is irrelevant noise to tissue
structure. In diseased liver such as fibrosis, muchminute diseased tissues are intermingled, and echo
from the diseased tissue obseaved with speckle.
Since these signals are short in time, it is buried in a
speckle and it is difficult to detect by visualobservation (Fig. 1). However, since these are thedirect reflective waves from diseased tissue, they
have the feature that it has been independent of the
speckle which is an interference noise (Fig. 2).

Fig.1 Image of liver fibrosis

signal element of diseased tissue

Amplitude

Fig.2 Elements of echo signal in liver fibrosis
In order to separate two independent ingredients by
ICA, the signal which observed the same
phenomenon simultaneously in two or morepositions is required. Then, we examined a means
to prepare two simultaneous observation signals
used as inputs to ICA. It is some methods ofchanging observation conditions in the same subject
and acquiring two echo images (RF signal), and amethod of using the ingredient approximated to the
speckle contained in the image for separation as the
2nd image.

160mm70mm

speckle reduction effectively by determining
observation conditions on the basis of the characterof a speckle. Ideally, it is desirable by irradiatingwith two or more signals simultaneously to observe
many observation signals at once.

(a) specimen(b) original echo image
Fig.3 Example of human fibrotic liver specimen.
3. Result of ICA
It was comfirmd that the gain of the echo
image used for an input seldom influences the
judgment of independency by basic examination.
On the other hand, it was estimated that the
influence of the irradiation frequency which is oneof the main causes for determining thecharacteristic of a speckle is large. Then, irradiation
frequency was changed to one human liver
specimen, two echo images were observed, and it
was considered as the input of ICA (Fig.3). Echodata of fibrotic liver were assumed by using
ultrasonic diagnostic equipment and a convex
scanning probe (Toshiba Medical Systems co.
modified SSA-770A and PVT-375AT). The focus
depth was 40 mm and the gain was assumed to be
80. The sending and receiving frequency was 4.0
MHz and 6.0 MHz, respectively.
Figure 4 shows the relult of ICA in humanliver specimen. Although the speckle has occurredin the whole image in an output 1, the minutecharacteristic structures are detected at the edge andparenchymatous liver part in the output 2. These
minute structures were in agreement with the fiber
structure of a liver specimen. The amplitude
distribution characteristic of the output 1 could be
mostly approximated by the Rayleigh distribution,and it was confirmed that only the speckle
ingredient had been extracted ideally.
4. Conclusion
The setting methods of the observation
conditions in ultrasonic diagnostic equipment differ
in neither a sound, nor brain waves, etc., and are notnecessarily completely in agreement with the theory
of ICA. However, it is possible to apply ICA to(a) Output 1(b) Output 2
Fig.4 Result of ICA in human fibrotic liver
specimen.
References
1. H. Shimura, T. Yamaguchi, H. Suyari and H.
Hachiya：IEICE Rep. US2006-15 (2006) 1. [inJapanese]

3P7a-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 441- 442
11-13 November, 2008

Influence of Blood Vessel Wall Motion on Shear Rate
Estimation in Blood Flow
血流内のずり速度推定における血管壁運動の影響
Naotaka Nitta (Inst. for Human Sci. & Biomed. Eng., AIST)新田尚隆 （産総研 人間福祉医）

1. Introduction
Relationships between the intravascular wall
shear stress in flow dynamics, and the progress ofarteriosclerosis plaque generation have beenclarified by some studies [1]. Since the shear stressis defined by multiplying the viscosity by the shear
rate, it is important that both factors can be
estimated accurately [2-3]. Among them, the shear
rate is an important factor to determine theestimated shear stress distribution. Hence, someinvestigations to improve the accuracy of shear rateestimation are conducted [4]. However, the finding
with respect to the influence of blood vessel wallmotion on shear rate estimation in blood flow is
insufficient. Therefore, in this study, with the aim of
the optimal wall filter design for the shear rateestimation, the above influence is investigated.
2. Shear rate estimation
Shear rate is defined as the derivation ofvelocity profile as follows.
dv( x)(1)v r ( x) =dx
where v r (x) , v(x) and x indicate the shear rate,
velocity vector and depth direction, respectively.
3. Simulation
Fig.1 shows the simulated radio frequency(RF) signal with a center frequency of 10 MHz anda signal-to-noise ratio (SNR) of 20 dB. This signal
is produced by convolving the scatterer (600
particles/mm3) and a pulse with 6 waves, andincludes echoes from the walls and blood cells.
Blood vessel has a radius of 2 mm and its luminal
center lies at a depth of 15 mm from the surface ofan ultrasonic probe. Blood flow is assumed to be aparabolic shape with a peak velocity of 0.2 m/s, andthe ultrasonic beam incident angle is set to 60
degree. In order to measure the velocity, thesuccessive 8 pulses are transmitted at a pulse
repetition frequency (PRF) of 5 kHz.

-----------------------------------------------------------n.nitta@aist.go.jp

In order to investigate the influence of bloodvessel wall motion on shear rate estimation in blood
flow, the dilative and contractive wall motions areadded. Here, the dilative and contractive rates aredefined as a ratio of the wall displacement during
two pulses transmission interval, which corresponds
to a reciprocal of PRF, to the initial diameter oflumen, and the motions from -0.4 % (contraction)
to 0.4 % (dilation) are induced.
Vessel wall

0

10

20

30

Depth (mm)Fig.1

RF signal from the vessel wall and blood cells.

4. Results
Fig.2 shows the results of estimated (a)velocity and (b) shear rate profiles during dilation,
respectively. Here, the velocity profiles were
estimated by the autocorrelation method without
any wall filter, and the shear rate profiles were
estimated by differentiating the above velocity
profiles using the differential window width of 0.6
mm.
Fig.3 shows the results of estimated (a)velocity and (b) shear rate profiles duringcontraction, respectively. In Fig.2(a) and Fig.3(a),the wall motions were estimated beside the velocity
profiles, and as predicted easily, the resultant shear
rate profiles in Fig.2(b) and Fig.3(b) included two
false peaks beside the desirable shear rate.
Fig.4 shows the summarized evaluation
results with respect to root mean square error(RMSE) of (a) velocity and (b) shear rateestimations, respectively. It should be noted that the
RMSE exhibits an asymmetry property. That is, theRMSE in dilation is smaller than that in contraction.
These findings are useful for designing the optimal
wall filter in estimating the shear rate.

0.0%

+0.1%

+0.2%

+0.3%

+0.4%

0.15
Velocity (m/s)

0.02
RMSE of velocity (m/s)

Ideal

0.1
0.05
0
-0.05
0

10

20

0.015
0.01
0.005

30

0
-0.4 -0.3 -0.2 -0.1

Depth (mm)00.1 0.2 0.3 0.4

Dilation and contraction rate (%)

Ideal

0.0%

+0.1%

+0.2%

+0.3%

+0.4%

(a)

150
100
50
0
-50
-100
-150

20

0

10

20

30

Depth (mm)(b)
Fig.2 Estimated (a) velocity and (b) shear rate profiles
during dilation.

RMSE of shear rate (s-1 )Shear rate (s-1 )

(a)

17.5
15
12.5
10
-0.4 -0.3 -0.2 -0.1

0

0.1 0.2 0.3 0.4

Dilation and contraction rate (%)
Ideal

0.0%

-0.1%

-0.2%

-0.3%

-0.4%

(b)

Velocity (m/s)

0.15

Fig.4
RMSE of (a) velocity and (b) shear rateestimations.

0.1
0.05
0

5. Conclusion

-0.05
0

10

20

30

Depth (mm)Shear rate (s-1 )

(a)
Ideal

0.0%

-0.1%

-0.2%

-0.3%

-0.4%

150
100
50
0
-50
-100
-150
0

10

20

30

Depth (mm)(b)
Fig.3 Estimated (a) velocity and (b) shear rate profiles
during contraction.

In this study, the influence of blood vessel
wall motion on shear rate estimation in blood flow
was investigated. These findings are useful for
designing the optimal wall filter in estimating theshear rate.
References
1. H.M. Honda, T. Hsiai, C.M. Wortham: Atherosclerosis.
158 (2001) 385.
2. N. Nitta, K. Homma：Trans. J. Soc. Med. Biol. Eng.
44 (2006) 190.
3. N. Nitta, K. Homma : Jpn. J. Appl. Phys. 44 (2005)
4602.
4. N. Nitta, N. Takeda : Jpn. J. Appl. Phys. 47 (2008)4209.

3P7a-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 443- 444
11-13 November, 2008

Accuracy Evaluation for High-Frequency UltrasonicMeasurement of Viscoelasticity of Radial Arterial Wallby Basic Experiments
高周波超音波を用いた橈骨動脈壁粘弾性計測法の基礎実験による精度評価Kazuki Ikeshita1†, Hideyuki Hasegawa2,1 and Hiroshi Kanai1,2 (1 Grad. School of Eng.,
Tohoku Univ.; 1 Grad. School of Biomedical Eng., Tohoku Univ.)
池下和樹 1，長谷川英之 2,1，金井 浩 1,2（1 東北大院 工; 2 東北大院 医工）

1. Introduction
The endothelial dysfunction is considered to
be an initial step of atherosclerosis1). Additionally, it
is reported that the smooth muscle, whichconstructs the media of the artery, changes its
characteristics
owing
toatherosclerosis2).
Consequently, it is important for early preventive
treatment to noninvasively assess the endothelial
function and the mechanical property of the media
which is mainly composed of smooth muscle.
For the evaluation of the endothelial function,
there is a conventional technique for measurementof the transient change in the inner diameter of thebrachial artery caused by flow-mediated dilation(FMD) after the release of avascularization3). For
more sensitive and regional evaluation, wedeveloped a method for direct measurement of thechange in the elasticity of the intima-media region
due to FMD4,5). Additionaly, we proposed a newnoninvasive method for measurement the transientchange in the stress-strain relationship owing to the
FMD at the radial artery for measurement of
mechanical property of the media6).
From the stress-strain relationship, theviscoelasticity of the intima-media region using theleast-square method to investigate the transientchange in the viscoelasticity due to FMD. In thisstudy, the accuracy of the method of measuring theviscoelasticity of radial arterial wall was evaluatedby basic experiments.
2. Principles
2.1 Measurement of stress-strain relationship of
the intima-media region in the radial arterialwall
To noninvasively assess the stress-strain
relationship of the intima-media region of the radial
arterial wall, it is necessary to measure waveformsof the change in thickness (strain) and the bloodpressure (stress) continuously. The minute change
in the thickness of the radial arterial wall, h(t), attime t during a cardiac cycle was measured by the-----------------------------------------------------------E-mail:{kanai, hasegawa, ikeshita}@us.ecei.tohoku.ac.jp

phased-tracking method 7). To obtain the change inthickness, the velocities of the artery wallboundaries
A(lumen-intima)
andB(media-adventitia) were estimated. The change inthickness, Δh(t), between two different depths, dA
and dB, in the arterial wall along an ultrasonic beam
was obtained from the difference between
displacements, x(t; dA) and x(t; dB), at these two
positions as follows;Δhˆ(t ) = xˆ(t; d ) − xˆ(t; d )
A

B

(1)
= ∫ {vˆ (t; dA ) − vˆ (t; dB )}dt,
0
where ^ means an estimate.
The blood pressure waveform p(t) was
simultaneously and continuously measured by asphygmometer which automatically optimizes the
position of the sensor for blood pressure
measurement. Therefore, we could obtain the
stress-strain relationship noninvasively.
t

2.2 Viscoelasticity estimation of arterial wallusing least-square method
The smooth muscle constructs the media andit is the main source of the viscoelasticity of thevessel wall8). By assuming the Voigt model as a
viscoelastic model of the intima-media region, thestress-strain relationship is given byτˆ (t ) = Es γ(t ) + ηγ& (t ) + τ0 ,(2)

where τ̂(t ) is the stress and γ (t ), γ& (t ), Es, and η arestrain, strain rate, static elasticity, and viscosity
coefficient, respectively. The measured strain γ(t) is
the incremental strain due to the pulse pressure,
whereas the measured stress includes the bias stress(diastolic blood pressure). Therefore, τ 0 is added to
the right-hand side of eq. (2) as the bias stresscorresponding to diastolic pressure.
The parameters in eq. (2), Es, η, and τ0, areestimated using the least-square method byminimizing the mean squared error, α, between themeasured and model stresses τ(t ) and τ̂(t ).
2.3 Procedure for basic experiment
In the basic experiment (Fig. 1), ultrasonicRF echoes (transmit: 22 MHz) were acquired at a

sampling frequency of 66.5 MHz for 2 s and aframe rate was about 160 Hz. In this experiment, weused a linear type probe which scans 127 positions. Two
different homogeneous cylindrical phantoms madefrom silicone rubber were measured. The elastic
moduli of these phantoms have been alreadymeasured (phantom A: 490 kPa and phantom B:
750 kPa). The wall thickness was 1 mm. Thechange in internal pressure, Δp(t), which wasapplied using a flow pump, was measured by apressure sensor. The transient change instress-strain relationship during a cardiac cycle wasobtained from the measured change in thickness,
Δh(t), and the internal pressure Δp(t).

where M, N, v(t ) and v (t ) are the number of beams,
the number of data in one cycle of the flow pump,measured velocity and mean velocity spatiallyaveraged for 127 beam positions, respectively. The
averaged standard deviation σ for phantoms A and
B were 0.0486 mm/s and 0.0464 mm/s, respectively.
These are 4.7% and 6.3% of the maximum
velocities.

Fig. 3 Stress-strain relationship of phantoms A and B.
Fig. 1 Schematic diagram of basic experiment.

3. Results
Figure 2(a) shows a B-mode image of thesilicone rubber phantom A. The lines k and l show
tracking points assigned at the outside and insideedges of the anterior wall of the silicone rubber.
Figure 2(b) and 2(c) show the estimated velocitiesof these edges. The distance between k and l was set
at 1 mm.

Fig. 2 (a) B-mode image of the silicone rubber.
(b) and (c) Estimated velocities at lines k and lobtained at 127 ultrasonic beam positions.

The accuracy of the estimation of theviscoelasticity depends on the accuracy of themeasurement of the velocity of the wall. By
assuming the constant movement of homogeneous
phantom, the accuracy of the estimated velocities
can be evaluated by the standard derivation among
velocities obtained at 127 beam positions. The
averaged standard derivation σ is expressed asσ=

1 N∑σ(t ),
N n=1

σ(t ) =

(3)

1 M
2
∑ {vh (t + Ts ) − vh (t )} ,M m =1Figure 3 shows the stress-strain relationshipsof phantoms A and B obtained at a beam position.
The slope and area of the stress-strain loop show
the elasticity and ratio of elastic modulus and loss
modulus. From the Fig. 3, the elasticity of phantom
A is smaller than that of phantom B, and theviscosity of phantom A is larger than that ofphantom B.
We estimated the static elasticity Es andviscosity η from the stress-strain relationship. The
average and standard deviation of static elasticity
and viscosity coefficients of phantom A and B were
223.7±143.1 kPa, 992.1±1293.6 kPa, 1.44±1.47• and 0.69±4.48 kPa,,s.
•
kPa,,s
4. Conclusion
In this study, from the measured stress-strain
relationship, we estimated the viscoelasticity of thesilicone rubber noninvasively. This method has apotential for the noninvasive measurement ofviscoelasticity of the arterial wall. However, theproposed method still requires the improvement of
the measurement of strain rate.
References
1. R. Ross: N. Engl. J. Med. 340 (1996) 115.
2. Y. Matsuzawa: Jpn. J. Clin. Med. 51 (1993) 1951.
3. M. C. Corretti, et al.: J. Am. Coll. Cardiol. 39(2002) 257.
4. H. Hasegawa, et al.: J. Med. Ultrason. 31 (2004)
81.
5. T. Kaneko, H. Hasegawa and H. Kanai: Jpn. J.
Appl. Phys. 46 (2007) 4881.
6. K. Ikeshita, H. Hasegawa and H. Kanai: Jpn. J.
Appl. Phys., 47 (2008) 4165.
7. H. Kanai, et al.: IEEE Trans. Ultrason.
Ferroelectr. Freq. Control, 43 (1996) 791.
8. K. Hirata et. al.: JSME Mechanical Engineer’s
Handbook C6. JSME, Tokyo, Japan (1998) 147.

3P7a-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 445- 446
11-13 November, 2008

Optimization of Window Size and Search Region in 2D
Correlation Function for Assessment of Regional Myocardial
Contraction and Relaxation
心筋収縮拡張特性計測における 2 次元相関窓長と探索領域の最適化
Yasunori Honjo1†, Hideyuki Hasegawa2, 1 and Hiroshi Kanai1, 2 (1 Grad. School of Eng.,
Tohoku Univ.; 2 Grad. School of Biomedical Eng., Tohoku Univ.)
本庄泰徳 1，長谷川英之 2, 1，金井

1.

Introduction

Methods for imaging of 2-D strain rate in theheart wall are useful for quantitative evaluation of
the regional heart function. The 2-D strain rate andheart wall motion have been estimated by analgorithm, speckle tracking and so on. However,important parameters in the algorithm, the optimal
sizes of a region-of-interest (ROI) and search region,
have not been thoroughly investigated.
In this study, the optimal values of theseimportant parameters were determeind, and the 2-D
heart wall motion was estimated by 2-Dcross-correlation between RF echoes.
2. Principles
2.1 2D cross-correlation function
In this study, 2-D displacement was estimatedby 2-D cross-correlation between RF echoes. The
correlation coefficient rn(ΔN, Δl, Δd) at the axial
and lateral shifts, Δd and Δl, is calculated from RF
signal rfn(l, d) at depth d and beam position l in then-th frame as follows:rn (ΔN , Δl , Δd )
l+L 2

=

d +D 2∑ ∑1{rf n (i, j ) ⋅ rf n + ΔN (i + Δl , j + Δd )},A i =l − L 2 j = d − D 2(1)( A = ( L + 1)( D + 1) σ n ,l ,d σ n + ΔN ,l + Δl ,d + Δd )where σn,l,d is the standard deviation of the RF
signal rfn(l, d) in an (L × D) ROI. RF signals in the
ROI in the n-th frame are compared with those inthe (n + ΔN)-th frame. The ROI in the (n + ΔN)-thframe is shifted by Δd and Δl in the axial and lateral
directions relative to those in the n-th frame.
2.2 Reconstructive interpolation
One of the problems in the estimation of 2-D
strian rate is the anisotropic spatial resolution. The
spatial resolution in the lateral direction is much
lower than that in the axial one. The coasely
sampled 2D cross-correlation function is an inexact-----------------------------------------------------------E-mail: (kanai,hasegawa,honjo)@us.ecei.tohoku.ac.jp

浩 1, 2 （1 東北大院 工; 2 東北大院 医工）

estimator of the location of the peak. Therefore, inorder to overcome this problem, sampledcorrelation function was interpolated to improve theprecision of displacement estimation by means ofreconstructive interpolation [1].
This method is a time-domain techniquebased on analog signal reconstruction theory. It is
possible to interpolate the sampled cross-correlation
function at an arbitrary time by means of low-passfilteration. The interpolated cross-correlation
function r(t) is expressed as follows:r (t ) =Nc 2⎡ π (t − nTs ) ⎤ ⎡ π (t − nTs ) ⎤ , (2)⎥ wh ⎢
⎥
Ts
Ts
⎦ ⎣
⎦

∑ r (nT )sinc ⎢⎣sn=− Nc 2

where Ts is the sampling interval, Nc is the numberof the sampled cross-correlation function, and wh is
the Blackman window.
3. Determination of optimal parameters
3.1 Determination of the size of a search region
At first, one of the important parameter, theoptimal size of a search region, was determined tosuccessfully track the 2-D heart wall motion.
The size of a search region can be rephrased
as the number of sampled points, the length ofcross-correlation function. Therefore, the effect of
the number of sampled correlation function wasinvestigated by means of a simulated sinusoidal
wave. Waveforms sampled at intervals of θs=3～
120 degrees were interpolated by reconstructive
interpolation so that the sampling interval became 3
degrees.
Figures 1(a) and 1(b) show the differencesε(θs) between the peak positions of true andsampled correlation functions evaluated at thedifferent number of sampled point Nc. The
differences ε(θs) is defined using peak positions P0
and Pθs of true and interpolated correlation
functions as follow:
ε (θ s ) =Pθ s − P0
P0

,

(2)

（a）

（b）
Fig. 1: Error ε(θs) between the interpolated peaks andthe true peaks of correlation functions between
simulated sinusoidal functions (a) P0=1, (b) P0=-1.

As shown Fig. 1, the error decreased sufficiently at
a number greater than 8 sampling points. The sizeof a search region should set as narrow as possible
because there may be several regions in the post
frame which have echo patterns similar to that in
the ROI in the previous frame when the size of thesearch region is too large. Therefore, the size of thesearch region Nc was determined to be 8 (8 degree
×6 mm).
3.2 Determination of the size of a ROI
To determine the optimal size of an ROI,ROIs with different sizes (l × d) = ((1.5 ～ 7.5
degree)×(0.1～3.1 mm)) were examined. The 2-D
displacement of an ROI in the IVS was estimatedby 2-D cross-correlation function using ROIs withdifferent sizes. The reliabilities of the axial andlateral displacements obtained by 2-D tracking were
evaluated using correlation coefficients between
displacements estimated by the 2-D method andcorresponding displacements obtained by the 1-D
method in two different measurements [2].
As shown in Fig. 2(a), correlation coefficientis totally high (0.9~0.95). This result shows theaxial displacement can be estimated accurately by
2-D tracking with any size of an ROI. On the other
hand, Fig. 2(b) shows different tendency comparedwith Fig. 2(a). The distribution of correlation
coefficients showed a dominant peak at a size of an
ROI of (4.5 deg × 2.1 mm). Therefore, in this study,
the size of an ROI was determined to be (4.5
deg × 2.1 mm).

Fig. 2: Cross-correlation coefficients (a) between theaxial displacement estimated by the 2-D method andreference and (b) between the lateral displacement
estimated by the 2-D method and reference.

4.

In vivo experiment
The motion of an arbitrary region in theinterventricular septum (IVS) was estimated by 2-D
tracking. The 2-D cross-correlation function was
calculated between two consecutive frames. The
size of a search region was routinely determined by
the length corresponding to 8 number of beams (8degree×6 mm). The size of an ROI was set at thedetermined optimum size (lateral axial) = (4.5 deg
×2.1 mm).
Figures 3(a) and 3(b) show the lateral andaxial displacements, respectively. Displacements
estimated by the 2-D method (solid line) werecompared with those estimated by the establishedmethod, 1-D phase-sensitive method (dashed line)[2]. These displacements by the 2-D method wellcorresponded to the references by the 1-D
phase-sensitive method. Figure 3(c) shows that
two-dimensional IVS motion obtained by the 2-D
correlation function. The IVS moved to the apicalside during cardiac systole and then, it began toreturn to the original position during diastole.

（a）

apex

basal

（c）

RV

（b）
LV

Fig. 3: (a) Displacement in the lateral direction. (b)Displacement in the axial direction. (c) 2-D displacement

Fig. 4: Maximum correlation coefficient during one
cardiac cycle.

5.

Conclusion
Regional heart wall motion was measured athigh temporal and spatial resolutions. As shown Fig.
4, maximal correlation coefficients during one
cardiac cycle was more than 0.6 [3], and in vivo
experimental results show the possibility of thismethod for measurement of two-dimensional heart
motion to assess the regional myocardial strain rate.
References
1. I. Cespedes et al.: Ultrason. Imaging. 17 (1995)
pp. 142-171.
2. H. Kanai et al.: IEEE Trans. UFFC., 43 (1996) pp.
791-810.
3. I. Akiyama et al.: Trans. IEICE., D-71 (1988) pp.
733-736.

3P7b-8

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 447- 448
11-13 November, 2008

Problems in Deriving the Soft-Tissue Thermal Index(TIS)
Using ISPTA in the Near Field
ISPTA
Soft-Tissue Thermal Index(TIS)         

Masahiro Yoshioka‡ (NMIJ, AIST)‡

1. Introduction
The thermal index (TI) and mechanical index(MI) are indices used for evaluating medical
diagnostic ultrasonic equipment. IEC 62359 is theinternational standard for deriving TI and MI1). TI
gives information about the temperature rise intissue caused by ultrasonic absorption and it isdefined as the ratio of the acoustic output power at
a specified point to that required to raise thetemperature at that point by 1 ˚C for a specifictissue model. The soft-tissue thermal index (TIS) isa TI that is appropriate for soft tissues and it isderived from the measured values for the ultrasonic
output power and intensity radiated in water. In thisreport, problems in deriving the TIS using the
spatial-peak temporal-average intensity in the nearfield are investigated.
2. Derivation of TIS

1)

2.1 Procedure for deriving TIS
The procedure for deriving the TIS of IEC
62359: 2005 differs according to the radiating areaof the ultrasonic transducer Aaprt (cm2) used. In thisreport, the derivation for the case Aaprt > 1 cm2 isconsidered. z (cm) is the depth from the tissue
surface contacted by the ultrasonic transducer asshown in Fig. 1. The acoustic output power
contributing to tissue temperature rise PP(z) (mW)is given by Eq. (1).
PP ( z ) = min Pα ( z ), I SPTAα ( z ) × 1cm 2(1){

Pα ( z ) = P × 10}

−αzf awf / 10I SPTAα ( z ) = I SPTA ( z ) × 10

(2)
−αzf awf / 10

(3)
Where P (mW) is the acoustic output power at theradiation surface of the transducer, ISPTA(z)(mW/cm2) is the spatial-peak temporal-averageintensity in the plane at a depth z in water, fawf(MHz) is the ultrasonic frequency and α = 0.3(dB/cm/MHz) is the acoustic attenuation coefficientof tissue. zS (cm) is the depth having the highest
value of PP(z) in the range satisfying z zbp (cm). zbp
is the minimum depth for measuring ISPTA(z) and it
is given by the following equation.
-----------------------------------------------------------masahiro.yoshioka@aist.go.jp

Ultrasonictransducer
Radiation surface

Soft tissue
Acoustic attenuation
coefficient α

Depth

z

Fig. 1 Illustration of soft tissue being irradiated byultrasound waves from a transducer in contact withthe surface of the soft tissue.

zbp = 1.5Deq = 1.5 πAaprt / 4(4)Where Deq (cm) is the equivalent aperture diameterof the ultrasonic transducer. Considering that thetemperature increase is greatest at the depth zS, theTIS is given by:TIS =PP ( z S ) f awf
C TIS

where CTIS (= 210 mW MHz) / fawf is the acoustic
output power for raising the tissue temperature by 1
˚C.
2.2 Perfusion assumption
As eq. (5) shows, PP(z) is the criticalparameter for deriving the TIS. It is obtained in IEC
62359 by applying a perfusion assumption (with aheat perfusion length of 1 cm); specifically, if thebeam area is less than 1 cm2, the acoustic output
power controls the temperature rise and if it isgreater than 1 cm2, the intensity controls it. In eq.
(1), which is used to derive PP(z), the beam area isjudged to be less than 1 cm2 or not by comparing
Pα(z) and ISPTAα(z) × 1 cm2.
3. Problems in deriving TIS
3.1 Derivation of zS
In this report, a 3.5-MHz ultrasonictransducer with a 1.4-cm-diameter plane circularsurface (radiating area of 1.5 cm2) used for general3.2 Derivation of TIS in the near field
Because the beam area at a depth close toradiation surface is the same as the radiation surface
area, the beam area of a transducer with Aaprt = 1.5
cm2 will be greater than 1 cm2. However, as Fig. 2
shows, there are some depths z at which Pα(z) <ISPTAα(z) × 1 cm2. The TIS is overestimated in thiscase. This overestimation is due to estimating thebeam area by comparing Pα(z) and ISPTAα(z) × 1 cm2.
This method for estimating the beam area can beapplied only in the far field. Moreover, the acoustic
output power in the range of 1 cm2 cannot bederived as ISPTAα(z) × 1 cm2 in the near field.
The TIS should be thus derived using the
spatially averaged intensity for 1 cm2 in the nearfield. Since the value of the spatially averaged
intensity depends on the location of the 1-cm2
region, in this report, ISATA1×1(z) is defined as the
maximum
spatial-average
temporal-averageintensity for 1 cm2 at a depth z. It is proposed that
the TIS be derived using P’α(z) instead of Pα(z)using the following equations.
'

PP ( z ) = I SATA1×1α ( z ) × 1cm 2
I SATA1×1α ( z ) = I SATA1×1 ( z ) × 10 −αzf awf / 10
The calculation results of ISATA1×1α(z) for theultrasonic transducer described in Section 3.1 areplotted in Fig. 2. zS and the TIS when the soundpressure on the radiation surface of this transducer
is 10 kPa are compared in the following threederivation methods.
1) zbp = 2.1 cm, using PP(zS) of eq. (1) (method of
IEC 62359: 2005): zS = 2.1 cm, TIS = 0.104
2) zbp = 0.3 cm, using PP(zS) of eq. (1):zS = 0.4 cm, TIS = 0.157
3) zbp = 0.3 cm, using PP’(zS) of eq. (6):zS = 0.3 cm, TIS = 0.106
Method 2) is the case when the hydrophone for(10 dB/div.)

ISATA1x1α(z) x 1cm2Pα(z), ISPTAα(z) x 1 cm2,

medical diagnostic ultrasonic equipment is
considered. The parameters Pα(z) and ISPTAα(z) × 1
cm2 of the ultrasonic transducer are derived fromultrasound pressure distributions, which arecalculated numerically using the Rayleigh integral
solution2). The calculation results are plotted in Fig.
2. From eq. (4), zbp is found to be 2.1 cm, andconsequently zS = 2.1. However, as Fig. 2 shows,
PP(z) increases as z decreases below zS. Moreover,
the tissue temperature rise is highest at depths close
to the radiation surface when the ultrasonicfrequency and the curvature radius of the transducer
are high, as shown in Fig. 2[3,4]. Since the depth atwhich the temperature rise is greatest zS is an
important parameter for users of medical diagnostic
ultrasonic equipment, it is problematic if zS cannot
be accurately determined. To overcome thisproblem, it is necessary to reduce zbp to a depthclose to the radiation surface.

zS = 2.1 cm in IEC Standard







Depth z (cm)Fig. 2 Pα(z) (solid line), ISPTA(z) × 1 cm2 (broken line)
and ISATA1×1(z) × 1 cm2 (dashed line) for 3.5-MHz
ultrasonic field radiated from 14-mm-diameter planecircular transducer.

measuring the intensity is as close as possible to theultrasonic transducer, in contrast with method 1)
described in IEC 62359: 2005. Using method 2), zS
is found to close to the radiation surface, reflecting
the same as the tendency as the tissue temperature
rise[4]. Therefore, the TIS is derived from theacoustic output power Pα(z); however, the beam
area is greater than 1 cm2. In method 3), which uses
ISATA1×1(z) instead of ISPTAα(z) that method 2) uses, zS
is also found to be close to the radiation surface andthe TIS is calculated to be 0.67 times that in method2). Because the ratio of the two TISs given bymethods 2) and 3) is according to 1 cm2 / Aaprt =0.65, it is considered that the overestimation of the
TIS can be removed by using spatial-averaged
intensity rather than the spatial-peak intensity.
4. Summary
When deriving the TIS using IEC
International Standards, the depth of the highest
temperature rise cannot be accurately determined
and the acoustic power in the range of 1 cm2 cannot
be derived as ISPTAα(z) × 1 cm2 in the near field. Inorder to overcome these problems, a derivation
using the spatial-averaged intensity for 1 cm2 is
proposed.
Acknowledgment
The author expresses gratitude to themembers of Japanese National Committee of
IEC/TC87 (Ultrasonics) for useful discussions.
References
1. IEC 62359: 2005.
2. G. R. Harris: J. Acoust. Soc. Am. 70 (1981) 10.
3. M. G. Curley: IEEE Trans. U.F.F.C., 40 (1993)
59.
4. O’Brien and D. S. Ellis: IEEE Trans. U.F.F.C., 46(1999) 1459.

3P7b-9

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 449- 450
11-13 November, 2008

Basic Verification of the Tissue Effect of
An Ultrasonically Activated Scalpel
超音波凝固切開装置の生体作用の基礎検討
Masaru Oya1†, Tadashi Yamaguchi2, Hideki Hayashi2, and Hiroyuki Hachiya3(1Graduate school of Advanced Integration Science, Chiba Univ.; 2Resarch Center for
Frontier Medical Engineering, Chiba Univ.; 3Graduate School of Sci. and Eng., Tokyo
Institute of Technology)
大屋優 1‡, 山口匡 2, 林秀樹 2, 蜂屋弘之 3（1 千葉大 融合科学; 2 千葉大 CFME;3 東工大 理工）

1. Introduction
Ultrasonically activated scalpel is usedwidely in laparoscope-assisted surgery, but it isconcerned that it may give undesirable damage tothe surrounding tissues during surgical operation bymechanical effect of sound.
In this paper, we present the vibration distributionof the blade using laser Doppler vibrometer. We
observe the generation of cavitation bubble in thewater and discuss the sound propagation and thebioeffect of sound in water.
2. Ultrasonically activated scalpel
Ultrasonically activated scalpel is a surgicalinstrument which can perform incision andcoagulation simultaneously. The active blade at the
tip is the specification which vibrates on thefrequency of 55.5 kHz. Incision is mechanically
performed by repeating that the vibrating blade
extends an organization locally beyond an elastic
limit. Coagulation is performed when the frictional
heat by vibration of a blade carries out heat
denaturation of the protein in a living body tissue. A
blade is roughly divided hook blade andlaparoscopic coagulating shears (LCS). Hook blade
can perform incision by making a blade press to anorganization, and if a flat portion is pressed, it canalso perform coagulation. And LCS can hold anorganization in the pad portion and active blade
portion which vibrate at high speed, and canperform incision and coagulation simultaneously.
3. Measurement of vibration distribution
In the blade portion in contact with a living
body tissue, in order to know what kind of vibrationis actually excited, the equipment was operated in
the air and vibration distribution was measured
using the scanning laser Doppler vibrometer(Polytec PVS-400). Measurement results are shown------------------------------------------------------------masaru-oya@graduate.chiba-u.jp

in Fig.1 and Fig.2. The gray scale images
correspond to the velocity component which isnormal to the image plane. Figure 1 shows that, inthe ball type blade, the whole surface of the ball isvibrating uniformly. Figure 2 shows thatbending-type vibration is excited on the front faceof LCS, and uniform vibration is excited on the end
face of LCS.

Fig.1 Measurement result of ball type blade(a) The front face of LCS(b) The end face of LCS
Fig.2 Measurement results of LCS

4. Observation of cavitation bubbles
When the cavitation bubbles collapse, they
force liquid energy into very small volumes.
Although the collapse of a cavity is a relatively
low-energy event, highly localized collapses canerode metals over time, and damage tissues. It is
important to observe where cavitation bubbles
generate.
We observed the generation of cavitation bubbles
around the blade in degassed water. We lighted up
the water from side of the water tank, and took
photographs using a high speed camera (Casio
EXILIM EX-F1).
Figure 3 shows cavitation bubbles near the ball
type blade and LCS. In these cases, theultrasonically activated scalpel worked withare carried by the flow of the acoustic streaming.
10

12000
10000
8000
絶対値

Amplitude(V)

5

0

6000
4000

-5
2000
-10
-0.5

0
Time(ms)

000.5(a) Sound waveform data

50
100
frequency [kHz]150(b) Frequency analysis
12000

10

10000
5
8000
絶対値

Amplitude(V)maximum output. It was observed that the amountof cavitation bubbles increases as we increased
output of the equipment. In ball type blade, bubbles
were generated from upper and lower part of blade
shown in Fig.3 (a). The generating positionchanged irregularly in the circumferential direction.
Since the vibration distribution of ball blade isalmost uniform, the generating position of thesecavitation bubbles changes irregularly. In LCS,
bubble generation mainly from the blade end wasobserved, shown in Fig.3 (b). The bubbles thatgenerated near the blade are carried by acoustic
streaming.

0

6000
4000

-5
2000
-10
-0.5

0
Time(ms)

0.5(c) Sound waveform data
8 mm

10 mm

0
0

50
100
frequency [kHz]150(d) Frequency analysis

Fig.4 Sound waveform and its spectrum (LCS)(a) Ball type blade(b) LCS

Fig.3 Cavitation.bubble from blades.

5. Acoustic pressure in the water
To estimate the ultrasound exposure of thetissue, it is necessary to measure the acoustic fieldaround the blade of an ultrasonically activatedscalpel. We measured the acoustic pressure emitted
from the blade in degassed water using hydrophone.
The hydrophone was fixed at the point of 30 mm
from the blade tip where cavitation bubbles exist,
The peak negative acoustic pressure is an importantparameter because it relates to the occurrence ofcavitation.
Figure 4 shows the received sound waveform fromthe LCS and its frequency analysis result. In Fig.4(b), we observed 55.5 kHz component which is thedriving frequency of this equipment. In Fig.4 (b)and (d), a frequency component near 10 kHz can beobserved. This frequency component was observed
when the cavitation bubbles generate. Then thisfrequency component and the generation of bubbles
are related, but the detailed mechanism of acoustic
wave emission is examined. We observed almost
same frequency components in ball type blade.
Figure 5 shows the results of sound pressure
measurement. The measured sound pressure issmaller than the sound pressure required forcavitation. It is thought that cavitation bubbles
generated locally near the blade, and the bubbles

The maximum negative sound pressure [Pa]0
Ball type blade
LCS

-5000
-10000-15000-20000-25000-30000
20

30

40
50
Input voltage [Vp̲p]60

Fig.5 The result of sound pressure measurement

6. Conclusion
In this paper, we measure acoustic
characteristics of the ultrasonically activated scalpel
to estimate the bioeffect. We measured the vibration
distribution of the blade of the equipment using
laser Doppler vibrometer. We observed thegenerating bubbles and sound pressure near theblade in the water. Cavitation bubbles generated
locally near the blade, and it is thought the collapseof bubbles is also localized near the blade.
References
1. Satoshi Tamura: Jpn. J. Appl. Phys. 45 (2006)
2842.
2. Steven D. McCarus: Physiologic mechanism of
the Ultrasonically Activated Scalpel. The Journalof the American Association of Gynecologic
Laparoscopists: Vol. 3, No.4, 601-608, 1996

3P7b-10

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 451- 452
11-13 November, 2008

Development of Area Image Sensing Method for Puncture
Needle Type Ultrasonography
穿刺型超音波顕微鏡用面走査手法の開発
Masasumi Yoshizawa† , Ryuuji Emoto, Hirotaka Kawabata (Tokyo Metropolitan
College of Industrial Technology), Takasuke Irie (Microsonic Co., Ltd.), Kouichi Itoh
(Hitachi-Omiya Saiseikai Hospital) and Tadashi Moriya (Professor Emeritus of Tokyo
Metropolitan Univ.)

吉澤昌純‡，江本龍二，川畑宏貴（都立産技高専），入江喬介（マイクロソニック（株）），伊東紘一 （常陸大宮済生会病院），守屋正（首都大名誉教授）

1. Introduction
Since the acoustic characteristics of livingorganisms are known to vary according to theirorganic composition, minute structural differences,and other factors,1) an acoustic microscope has been
applied to biological tissue characterization. Many
imaging methods for acoustic characteristics suchas the measurement of the speed of sound or
acoustic impedance have been developed foracoustic microscopes. They are useful for
intraoperative pathological examination because
staining is not required. In particular, since acoustic
impedance can be used to visualize a surface
without slicing a biological tissue, it may be applied
to endoscopic ultrasonography.2) However, nosuggestions for the sensing device and scanningmechanism for endoscopic ultrasonography havebeen made.
For endoscopic ultrasonograpy to faciliate
tissue diagnosis, we are developping the punctureneedle-type ultrasonography. Previously, wedemonstrated an imaging method for the acoustic
impedance difference for puncture needle-typeultrasonography using a thin rod with the focusing
end face.3) However, no suggestions for thescanning mechanism have been made. In this paper,
we describe an area image sensing method for the
acoustic impedance difference for punctureneedle-type ultrasonography using a thin rod.
2. Principle
Figure 1 shows the schematic of theequipment
forthepuncture
needle-typeultrasonography. The measurement principle of themethod was previously reported.3) The principle ofthe proposed scanning method in this case is basedon the movements of the end point of the lever asshown in Fig.2. In Fig.2, a thin rod is placed on thefulcrum. When the end point A rotates clockwise
forming a circle, the point B moves counterclockwise also forming a circle. By sensing theyoshizawa@acp.metro-cit.ac.jp

surface of the sample as a function of the angle (θ),
two dimensional scanning can be done.
Encapsulated
measurement
unit

Top cover of hollow pipe
Hollow pipe
NeedleScanning for imaging
Thin rod (as a transmission line and sensor)
Fig. 1. Basic concept for puncture needle-typeultrasonography.
Fulcrum
RotateθA

RotateB
Thin rod

Transducer

Fig. 2. Basic concept for area image sensing method..

3. Experiment and results
Figure 3 shows the schematic diagram of themeasurement. In this research, for the first step toconform the method, the thin rod was moved
horizontally. Figure 4 shows the measurement
system for horizontal scanning. In this experiment,a fused quartz rod with a diameter of 0.84 mm anda length of 74 mm as shown in Fig. 3 wasconnected to a transducer with a center frequencyof 9.0 MHz. The ends of the fused quartz rod wereflat polished. A burst wave having an amplitude of
5 V from peak to peak, a center frequency of 8.4
MHz, and a pulse width of 43 cycles was applied.
An aluminum plate was used as a sample.
Figure 5 shows the normalized amplitude of
the interference signal as a function of distancefrom center. Those data were obtained bymeasuring four times in different directions (rightControlCover of acoustic coupler
Thin quartz rod
Automatic Stage
Right
Center

40mm

40mm
Left

Computer

No.1
No.3

0.00
-1.5

-0.5

0.5

1.5

2.5

Distance from center [mm]Oscilloscope(a) Left direction
1.00

Transduce

Fig. 3. Schematic diagram of measurement.
Move by automatic stage
Rotate(a) Top view

0.40

-2.5

Burst Wave Generator

Thin rod

0.60

Data

Image object (Aluminum plate)

Rotate0.80

0.20

Transducer

Amplitude

Acoustic coupler

1.00

Amplitude

and left). The phase difference becomes
constructive interference condition when the
distance from center is 1.9 mm by simple arithmetic.
The amplitude envelope of the interference signal
has a peak when the length of the distance from thecenter is approximately 1.9 mm, as expected. Thismeans that the method performs the desired
operation.

0.80
0.60
0.40

No.2
No.4

0.20
0.00
-2.5

-1.5

-0.5

0.5

1.5

2.5

Distance from center [mm](b) Right direction
Fig. 5. Normalized amplitude of interference signal asa function of distance from center.

4. Conclusions
Cover of acoustic coupler Clip-on(b) Side view

In order to develop an area image sensing
method for the acoustic impedance difference forpuncture needle-type ultrasonography using a thinrod, we confirmed experimentally that the proposed
scanning method can be used for the area image
sensing.
Acknowledgment
This study was partially supported by the
Adamant Kogyo Company Limited.

(c) Picture of top view

References
1. R. C. Chivers: Ultrasound Med. Biol. 7 (1981) 1.
2. Y. Saijo, E. S. Filho, H. Sasaki, T. Yambe, M. Tanaka, N.
Hozumi, K. Kobayashi, and N. Okada: IEEE Trans. Ultrason.
Ferroelectr. Freq. Control 54 (2007) 1571.
3. M. Yoshizawa, T. Irie, K Itoh, and T. Moriya: Jpn. J. Appl.
Phys. 47 (2008) 4176.

(d) Picture of side viewFig. 4. Measurement system for horizontal scanning.

3P7b-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 453- 454
11-13 November, 2008

Inline Transmitter/Receiver System
without Direct Receiving of Transmitted Signals
送信信号の直接受信を回避可能なインライン送受信システム
Masayuki Tanabe†, Kan Okubo and Norio Tagawa (Facult. System Design, Tokyo
Metropolitan Univ.)
田邉将之‡，大久保寛，田川憲男 （首都大システムデザイン）

1. Introduction
It is important to obtain more fine images
with high spatial resolution and signal-to-noise ratio(SNR) in ultrasound medical imaging, especially inintravascular ultrasound (IVUS).1,2) To realize
higher spatial resolution, tissue harmonic imaging(THI)3,4) and the pulse compression technique(PCT)5) have been introduced. We havecontinuously examined frequency modulation (FM)chirp PCT from the viewpoint of fundamental
study,6-8) and already proposed an inline transmitter/receiver system for IVUS, which uses both of the
THI and the PCT.9) In this system, aPb(Zn1/3Nb2/3)O3-PbTiO3 single crystal (PZNPT) is used as a transmitter, and a polyvinylidene
fluoride (PVDF) film placed on the transmission
side of the PZN-PT is used as a receiver, andanother PVDF film placed on the reverse side of the
PZN-PT is used as a refenence. A PZN-PT issuitable for a transmitter because of its transmitting
performance, although its bandwidth is narrow10).
On the other hand, a PVDF is suitable for a receiver
since its bandwidth is effectively wide enough toreceive harmonic components.11,12) When a PVDF
film in front of the PZN-PT receives a transmitted
signal and an echo signal at the same time, byextracting the difference signal between the bothsignals each of which is received by the each PVDF
film, echo signal can only be obtained. In theprevious study, we investigated the effectivenessand the feasibility of canceling system. However, inconsideration of the practical use of this system, thereference PVDF should avoid receiving echo signal,i.e., it has to receive only tansmitted signal in orderto cancel the transmitted signal mixed into thesignals received by the reciver PVDF. In this study,
we newly propose an inline transmitter/receiversystem which has no undesirable echo signals.
2. Structure of proposed system
A diagram of the inline transmitter/receiversystem with canceling function and the proposed
structures to avoid receiving undesirable echo
signals are shown in Fig. 1. In this system, PVDF-----------------------------------------------------------Email: masatanabe@gmail.com

films are used as not only a transducer but also amatching layer. PVDC films are used as an
insulator in consideration of the actual system.
2.1 Type-1
A reflecting mirror is put on the side of thereference PVDF film; it is set at the left side of the
PZN-PT as shown in Fig. 1 (b), and can efficiently
reflect the transmitted signal passing through thereference PVDF film toward –y-direction so as todecrease the undesirable echo signals.
2.2 Type-2
A reflecting mirror is put on the side of thereceiver PVDF film being at the upper side of the
PZN-PT as shown in Fig. 1 (c), and reflects thetransmitted toward +x-direction and we use echo
signals for imaging. This type may lower SNR in
imaging against the type-1 because of the reflection
efficiency of the mirror, but we can rotate the mirror
instead of the transmitter/receiver for rotational
IVUS imaging and hence, a slip ring is not required.
IVUS probe
PVDC

MirrorPZN-PT PVDF

(c)

(b)
Preamplifier

AmplifierOscilloscope

Arbitrary waveform

(a)

y
x

synthesizer

Fig.1 (a) A diagram of inline transmitter/receiversystem with canceling function, and proposed
structures; (b) type-1 and (c) type-2

4. Results and Discussion
Figure 2 shows the difference voltage
between two PVDF films using the type-1 structurewith or without a target stainless steel. 28.0 mVp-p
echo signal from the target stainless steel isobtained, and is sufficiently larger than the echo
signal reflected directly from the mirror.
Figure 3 shows the difference voltage
between two PVDF films using the type-2 structure.
In this figure, 7.4 mVp-p echo signal from thetarget stainless steel was obtained at approximately
2.2 μs, and 0.73 mVp-p echo signal reflected
directly from the mirror is obtained from 0.7 μs.
The echo signal from the mirror is undesired for
imaging, and therefore we will reduce the signal asa future work.
5. Conclusion
Through these results, we confirmed thefeasibility of two types of proposed system. In near
future, we will examine a shape of the reflecting
mirror and apply these systems to the PCT and THI.
15
with a target
without a target

Voltage [mV]

10

5

0

-5

-10

-15
0

0.2

0.4

0.6

0.8

1

1.2

1.4

Time [μs]Fig. 2: Difference voltage between two PVDF films
using Type-1 structure with a target stainless steel(solid line) and without a target one (broken line)

42

Voltage [mV]

3. Experiments
In this study, PZFLEX, a standard finite
element method (FEM) simulator for ultrasoundpropagation, is used for the 2-dimensional
simulations. We examined the received difference
voltages between two PVDF films using the
proposed two structures. A sine wave, frequency of
20 MHz, duration of λ, voltage of 40 Vp-p isappiled to the PZN-PT as a transmitted pulse. The
thickness of PZN-PT, PVDC and PVDF are 90, 11
and 23.75 μm, respectively. The distance between
the target stainless steel and the IVUS probe is 0.5
mm.

0

-2

-4
0

0.5

1

1.5

2

2.5

3

Time [μs]Fig. 3: Difference voltage between two PVDF films
using Type-2 structure with a target stainless

References
1. I. H. Mita, H. Kanai, Y. Koiwa, M. Ichiki, and F.
Tezuka: Jpn. J. Appl. Phys. 40 (2001) 4753.
2. Y. Saijo, A. Tanaka, N. Owada, Y. Akino, and S.
Nitta: Ultrasonics 42 (2004) 753.
3. F. N. Demirbilek and Y. Yamakoshi: Jpn. J. Appl.
Phys. 42 (2003) 342.
4. M. E. Frijlinl, D. E. Goertz, L. C. A. van Damme,
R. Krams, and A. F. W. van der Steen: IEEE
Trans. Ultrason. Ferroelectr. Freq. Control 53(2006) 1844.
5. D. Y. Kim, J. C. Lee, S. J. Kwon, and T. K. Song:Proc. IEEE Ultrasonics Symp., 2001, p. 1477.
6. Y. Tonegawa, N. Tagawa, and T. Moriya: Jpn. J.
Appl. Phys. 43 (2004) 3076.
7. Z. Hu, T. Moriya, and Y. Tanahashi: Jpn. J. Appl.
Phys. 40 (2001) 3896.
8. Z. Hu, N. Tagawa, and T. Moriya: Jpn. J. Appl.
Phys. 39 (2000) 3233.
9. M. Tanabe, K, Okubo and N. Tagawa: Jpn. J.
Appl. Phys. 47 (2008) 4149.
10. J. Jin, K. K. Rajan, and L. C. Lim: Jpn. J. Appl.
Phys. 45 (2006) 8744.
11. T. Tamura, Y. Yoshida, H. Inoue, and K. Murata:
Jpn. J. Appl. Phys. 41 (2002) 3295/
12. I. Akiyama, A. Ohya, and S. Saito: Jpn. J. Appl.
Phys. 44 (2005) 4631.

3P7b-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 455- 456
11-13 November, 2008

Matching Layer Function of PVDF Receiver in Inline
Transmitter/Receiver System
インライン送受信システムにおいて受信機として用いる
PVDF の整合層機能
Makoto Miyata†, Masayuki Tanabe, Kan Okubo and Norio Tagawa (Facult. System
Design, Tokyo Metropolitan Univ.)
宮田誠‡，田邉将之，大久保寛，田川憲男 （首都大システムデザイン）

1.

Introduction

It is important to obtain high resolution andhigh signal-to-noise ratio ultrasonic medical images,
especially in intravascular ultrasound (IVUS). 1,2)
For this purpose, tissue harmonic imaging (THI) 3,4)
and the pulse compression technique (PCT) 5) havebeen appiled for IVUS. In preliminary study, we
have proposed an inline transmitter/ receiver system
for IVUS which uses THI and the PCT, andconfirmed that the each assertion is effective.6-9) In
this system, a Pb(Zn1/3Nb2/3)O3-PbTiO3 single
crystal (PZN-PT) is used as a transmitter, a
polyvinylidene fluoride (PVDF) film placed on thetransmission side of the PZN-PT is used as areceiver, and another PVDF film placed on thereverse side of the PZN-PT is used as a reference
receiver in order to prevent the transmitted signal
mixing with the echo signal. We have examined the
PVDF’s receiving capacity for harmoniccomponents with various thicknesses of 28, 52, and
110 mm. However, the measurement results are
sensitive to the experimental conditions and thefabrication of the transmitter/receiver system; hence,
we have obtained no unequivocal conclusion. This
study’s ojective is to clarify the suitable thicknessof the PVDF films in consideration of the total
performance for pulse compression imaging
through FEM simulations.

acoustic impedance of the matching layer, Z m ,placed between two materials whose acoustic
impedances are Z1 and Z 2 respectively, isformulated as Z m = Z1 ⋅ Z 2 . The acoustic
impedance of PZN-PT is 23 Pa･s/m3 and that ofwater is 1.52 Pa･s/m3. Therefore, the ideal acoustic
impedance of the matching layer in this system isapproximately 5.91 Pa ･ s/m3, and a PVDF
having an acoustic impedance of 4.02 Pa･s/m3 canbe used as a matching layer appropriately. A
matching layer should have a thickness of λ/4, in
which λ indicates the wavelength in a matchinglayer. In this study, we transmit an FM chirp signal
with a central frequency of 20 MHz, and speed ofsound of a PVDF is 2260 m/s. Hence, thewavelength of the central frequency isapproximately 113 μm, and the suitable thickness of
the PVDF film is 28.25 μm for this matching layer.
3. Experiments
In this study, PZFLEX, a standard finite
element method (FEM) simulator for ultrasoundpropagation, is used for the simulations. To evaluate
the suitable thickness of the PVDF film for the both
functions as a matching layer and a receiver, we
PVDF (reference receiver)
PZN-PT PVDF (receiver)

PVDC

Target2.

System Structure and Matching Layer

2.1 Structure of inline transmitter/receiver system
A diagram of the proposed system is shownin Fig. 1. A PVDF film used as a receiver works
also as a matching layer. PVDC films are used as an
insulator in consideration of the actual inline system.
The thicknesses of the PZN-PT and the PVDC are
90 and 11 μm respectively.
2.2 Matching layer function of PVDF
The PVDF receiver can be used also as amatching layer between the PZN–PT layer andwater, with which the catheter is filled. The-----------------------------------------------------------macoto.miyata@gmail.com

Preamplifier

AmplifierOscilloscope

Arbitrary waveform
synthesizer

Fig. 1 : Proposed inline transmitter/receiver system.

4. Results
Figure 2 shows the results of the voltages ofthe echo signals with respect to the thickness of the
PVDF film. From this figure, it can be confirmedthat the theoretically suitable thickness of 28.25 μm
is almost the best value. In Fig. 3, the received
waveforms with some thicknesses around 28.25 μm
are shown.
5. Conclusions
Through simulations, we confirmed that the
thickness of the PVDF film should be selected withrespect to the frequency used for imaging,
especially for the fundamental imaging. For the
harmonic imaging, we will verify the suitable
thickness of the PVDF film.

(b)Voltage [mVp-p]

6

(c)

4
(a)
2
(d)

0
0

20

40
60
80
Thickness of PVDF [μm]100Fig. 2 : Voltages of echo signals received by PVDF filmwith various thicknesses.

Voltage [mV] Voltage [mV] Voltage [mV] Voltage [mV]examined the voltage of the echo signals received
by the PVDF with varying the thickness of both the
PVDF films simultaneously. In these simulations,an FM chirp signal with a central frequency of 20
MHz, a bandwidth of 4 MHz, a pulse width of 5
μsec with the Hamming window, is used as atransmitted pulse. The thickness of the PVDF isvaried from 9.5 to 104 μm.
In our inline system, the transmitted signal is
expected to be mixed into the received signals.
Hence, by connecting the leading wires of both
PVDF films shown in Fig. 1, the directly received
transmitted signals of both PVDF films arecanceled and the desirable echo signal can beextracted. In consideration of the actual usage ofthis system, in these simulations, we evaluate theecho signals extracted by the above canceling
function.

4
2
0
-2
-4
4
2
0
-2
-4
4
2
0
-2
-4
4
2
0
-2
-4

(a)

(b)

(c)

(d)

0

1

2

3

4
5
Time [μs]

6

7

8

9

Fig. 3 : Instances of waveforms received by PVDF filmwith thickness of (a) 19 μm, (b) 23.75 μm, (c) 28 μm
and (d) 38 μm respectively.

References
1) H. Mita, H. Kanai, Y. Koiwa, M. Ichiki, and F.
Tezuka: Jpn. J. Appl. Phys. 40 (2001) 4753.
2) Y. Saijo, A. Tanaka, N. Owada, Y. Akino, and S.
Nitta: Ultrasonics 42 (2004) 753.
3) F. N. Demirbilek and Y. Yamakoshi: Jpn. J. Appl.
Phys. 42 (2003) 342.
4) M. E. Frijlinl, D. E. Goertz, L. C. A. van Damme,
R. Krams, and A. F. W. van der Steen: IEEE
Trans. Ultrason. Ferroelectr. Freq. Control 53(2006) 1844.
5) D. Y. Kim, J. C. Lee, S. J. Kwon, and T. K. Song:Proc. IEEE Ultrasonics Symp., 2001, p. 1477.
6) Y. Tonegawa, N. Tagawa, and T. Moriya: Jpn. J.
Appl. Phys. 43 (2004) 3076.
7) Z. Hu, T. Moriya, and Y. Tanahashi: Jpn. J. Appl.
Phys. 40 (2001) 3896.
8) Z. Hu, N. Tagawa, and T. Moriya: Jpn. J. Appl.
Phys. 39 (2000) 3233.
9) M. Tanabe, S. Xie, N. Tagawa, T. Moriya, and Y.
Furukawa: Jpn. J. Appl. Phys. 46 (2007) 4805.

3P7b-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 457- 458
11-13 November, 2008

Three-dimensional
Scatterer-size
Estimation
in
Dissected Human Lymph Nodes Using High-frequency
UltrasoundJonathan Mamou‡, a), Alain Coron b), Masaki Hata c), Junji Machi c),
Eugene Yanagihara c), Pascal Laugier b), and Ernest J. Feleppa a)a)F. L. Lizzi Center for Biomedical Eng. Riverside Research Inst., New York, NY, USA
UPMC Univ Paris 06, UMR 7623, LIP, Paris, F-75005, France, and
CNRS, UMR 7623, LIP, Paris, F-75006, Francec)University of Hawaii and Kuakini Medical Center, Honolulu, HI, USAb)

1. Introduction
High-frequency (i.e. >15 MHz) ultrasound(HFU) research is attracting considerable interest
because the short wavelengths (e.g., 100 µm at 15
MHz) and small focal-zone beam diameters of HFU
provide fine-resolution images. Studies havedemonstrated the unique ability of HFU systems toimage shallow or low-attenuation tissues forbiomedical applications. For example, HFU alreadyhas been successful for small-animal [1], ocular [2],intravascular [3], and dermatological imaging [4].
Most human lymph nodes have sizes
ranging from 2 to 8 mm in diameter, althoughsometimes larger sizes are encountered, e.g., in thecase of node-filling metastatic cancers. Therefore,
lymph nodes typically are small enough to be
imaged using HFU.
Quantitative ultrasound (QUS) is being
investigated by several research groups, and manytissue parameters have been estimated. This study
focuses on QUS methods to estimate scatterer size
from the spectrum of the radio-frequency (RF) echo
signals. This method is derived from the theoreticalframework of ultrasound scattering established by
Lizzi et al. [5] for biological tissues andsubsequently expanded by him and others [6].
Using frequency-dependent information derived
from RF backscattered signals allows quantitatively
assessing tissue micro-structural properties andrelating them to histological properties. Our
hypothesis is that scatterer-size estimates may help
to differentiate between cancer-containing nodes
and cancer-free nodes.
2. Methods
Lymph nodes were dissected frompatients with histologically proven primary cancers(e.g., breast, colorectal, and gastric cancers) at the
Kuakini Medical Center (KMC) in Honolulu, HI.
De-identified patient information was coded andsent to Riverside Research Institute (RRI) in New
York, NY. Pathologists at KMC provided RRI witha tracing of the boundary of each cancerous region
in every histological section for each node.
After excision by the surgeon, dissected
nodes were brought to the pathologist for grosspreparation. Then, individual, manually defatted,
fresh lymph nodes were placed in a water bath
containing isotonic saline (0.9% sodium chloride) atroom temperature and scanned individually.
Ultrasound data were acquired with a focused,single-element,
transducer(PI30-2-R0.50IN,
Olympus NDT, Waltham, MA) with an aperture of
6.35 mm and a focal length of 12.7 mm. The
transducer had a center frequency of 25.6 MHz anda minus-6-dB bandwidth that extended from 16.4 to33.6 MHz. The transducer was excited by a
Panametrics 5900 pulser/receiver unit. The RF echo
signals were digitized at 400 MHz. The spacing
between adjacent A-lines was 25 µm. A 3D scan ofeach lymph node was obtained by scanningadjacent planes every 25 µm to uniformly cover theentire lymph node.
After 3D ultrasound scanning wascompleted, a 3D segmentation algorithm was used
to detect the boundaries of the residual fat layer andof the actual lymph-node tissue.
Following 3D segmentation, scatterer-size
estimates were computed using 3D cylindricalregions of interest (ROIs) of 1-mm diameter and
1-mm length. Scatterer sizes were only estimatedwhen the ROI was entirely in the tissue region
found by the 3D segmentation algorithm. Eachindividual RF-segment spectrum within the ROI
was compensated for attenuation. The spectra ofeach RF segment within one ROI were averaged
and log compressed. A calibration spectrum was
obtained from a planar reflector and subtracted
from the ROI spectrum to obtain a normalized
spectrum. The normalized spectrum was fit to a
Gaussian scattering model [6], and the fit
parameters were inverted to obtain scatterer-size
estimates. The optimization bandwidth was varied
for each ROI based on a local SNR estimator. The
optimization bandwidth for ROIs having

The methods proposed herein currently
are being used on many (>100) human lymph-nodeacquisitions. Our expectation is that because
scatterer-size estimates describe microstructure
within the tissue, clinically useful differences
should exist between estimates for metastatic andnon-metastatic regions of lymph nodes.
Acknowledgment
This work was supported by NIH grant
CA100183.
References
1. D. H. Turnbull: Methods Mol. Biol. 135 (2000)
235.
2. R. H. Silverman, J. A. Ketterling, J. Mamou and
D. J. Coleman: Arch Ophthalmol. 126 (2008) 94
3. Y. Saijo, A. Tanaka, N. Owada, Y. Akino, andS. Nitta: Ultrasonics. 42 (2004) 753
4. M. Vogt M and H. Ermert: IEEE Trans. Ultrason.
Ferroelectr. Freq. Control. 54 (2007) 1551
5. F. L. Lizzi, M. Greenebaum, E. J. Feleppa, M.
Elbaum and D. J. Coleman: J. Acoust. Soc. Am.
73 (1983) 1366
6. M. L. Oelze, J. F. Zachary, and W. D. O'Brien,Jr.: J. Acoust. Soc. Am. 112 (2002) 1202

y=1.9 mm

11
12
13

1

Z (Depth) (mm)0113
X (mm)

245

x=2.5 mm

12
13
0

1

2
Y (mm)

30 z=12.1 mm
1X (mm)The results presented here pertain to theillustrative case of a 64-year-old male patient who
was diagnosed with stage-3 colon cancer. Fourlymph nodes were obtained from this patient duringcolon-cancer surgery. Three of the dissected nodes
were determined to be negative for metastatic
cancer and the fourth node was determined to bepositive. Figure 1 shows cross-sections through the
3D ultrasound volume of one of the negative nodes
augmented by the color-coded scatterer-size
estimates and the segmentation results. The
segmented fat region and lymph-node tissue regions
are inside a red and green boundary, respectively.
For this lymph node, the scatterer-size estimates
had an average of 21.5 µm and a standard deviationof 4.19 µm.
4. Conclusions

Scatterer-size estimates (μm)
10
15
20
25
30

Z (Depth) (mm)satisfactory SNR was chosen larger than that used
for ROIs having less satisfactory SNR. Using thelargest optimization bandwidth possible isadvantageous because theory predicts that thestandard deviation of the scatterer-size estimates isinversely proportional to the optimization
bandwidth.
Adjacent ROIs overlapped by 90% in 3D.
Scatterer-size estimates were color-coded andoverlaid over conventional B-mode images fordisplay. The scatterer-size parametric images had avoxel size of 0.1 x 0.1 x 0.1 mm because of the
90% overlap.
3. Results

2
3
4
5
0

1

2
Y (mm)

3

Fig. 1 Cross-section through a lymph-nodeprocessed with a 3D segmentation algorithm and ascatterer-size estimation routine. Segmentation
results are visible as the green and red boundaries
surrounding fat and lymph-node tissue, respectively.
Scatterer-size information was color-coded andoverlaid
overtheconventional
B-modecross-sections.

3P7b-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 459- 460
11-13 November, 2008

Frequency dependence of ultrasonic properties of bovine cortical bone
samples
Guillaume Haïat†1, Magali Sasso2, Salah Naili2 and Mami Matsukawa3
1

CNRS, Université Paris 7, Laboratoire de Recherches Orthopédiques, UMR CNRS 7052 B2OA,
10 avenue de Verdun, 75010 Paris, France, 2 Laboratoire de Biomécanique et Biomatériaux
Osteo-Articulaires, UMR CNRS 7052 – Université Paris 12, Créteil, France.3: Laboratory of
Ultrasonic Electronics, Doshisha University, Kyotanabe, Kyoto-fu 610-0321, Japan

1. Introduction
Quantitative ultrasound (QUS) techniques areused for bone assessment and estimation of fracture.
Cortical bone makes up for the compact part ofbone, mainly found in the shaft of long bones and in
the envelope of short bones.
The development of axial transmission
techniques enables the assessment of cortical bone.
Cortical bone is determinant in bone fragility since
it supports most of the load of the body, represents
80% of the skeleton mass and is primarily involved
in most of osteoporotic fractures. However,ultrasonic propagation in cortical bone is intricate
and the mechanisms involved in wave propagation
are still poorly understood. The main parameter ofinterest in axial transmission is speed of sound(SOS). Cortical bone is a dispersive media and only
few studies have focused on the understanding ofwave attenuation and velocity dispersion in corticalbone.
The objective of the present work is to demonstrate
the feasibility of Broadband Ultrasonic Attenuation(BUA) and velocity dispersion measurements inbovine cortical bone and to appraise its dependence
on bone mass, microstructure and anatomical
location.
2. Material and methods
Three left femurs of 36-months old cows were usedin the present study. Parallelepipedic samples(4~11mm side) were cut all along the bone axis andcircumference. First, the femur was cut into 5 rings.
Then, from each ring, 8 samples were taken in theanterior, posterior, medial, lateral and in the four
oblique parts of the bone. Bone Mineral Density
(BMD)
was
measured
by
dual
X-ray
absorptiometry (QRD-1000, Hologic) in the axial
direction. Cortical bone microstructure wasassessed using optical microscopy images of bone
sections cut from the top axial surface of eachsample. Samples were manually classified into 4
microstructures: plexiform (Pl), Haversian (H),porotic (Po) mixed (M) microstructures (made of
combined microstructures) [1, 2].
The plexiform microstructure is made of lamellae
having the vascular plexus sandwiched within.
-----------------------------------------------------------†:

guillaume.haiat@univ-paris-diderot.fr

Lamellae have a 100~200 µm thickness. Haversian
microstructure is made of osteons which are alignedin the axial direction. Osteons diameter is 150~300µm. Porotic microstructure can be found at parts
were muscles adhere and has the largest pores size
comprised between 50 and 300 µm.
Bone samples were assessed in a normal saline
solution (NSS) stabilized at 25±0.1°C. A pair of 8
Fi diameter3 Ult
ii broadbandt l t polyvinylidene
mm
self-made(PVDF) transducers was used. Each sample was
evaluated 4 times with repositioning in the axial,
radial and tangential directions.
BUA and dispersion were evaluated from ultrasonicmeasurements using a substitution method. We useda single sinusoidal pulse for the excitation oftransducer. It enables the BUA and dispersion
measurements.
Thefrequency
dependent
attenuation coefficient and phase velocity arederived from the ratio of the spectrum of the signaltransmitted through bone and through NSS bycorrecting from transmission and diffraction effects[3]. BUA (respectively dispersion) is defined as theslope of the frequency dependent attenuation(respectively phase velocity) and is evaluated on a 1
MHz-wide frequency range centred around 4 MHz.
3. Results and discussion
On the 1 MHz restricted bandwidth, the attenuation
coefficient and phase velocity are quasi linear withfrequency, which shows the feasibility of BUA anddispersion measurements.
The value of the averaged standardized coefficientof variation is equal 11.4% for BUA measurements
and the value of the averaged coefficient ofvariation is equal 1 m/s/MHz for dispersion
measurements.
ANOVA analysis revealed a significant directional
effect for BUA (p<0.002) but not for dispersion
measurements. Significant anatomical effects were
found for BUA (p<0.005) and dispersion (p<0.05)
measurements. BUA values in the three directions
are significantly positively correlated to BMD (R2 =0.44, p<10-5 in the axial direction) but when
considering plexiform microstructure only, nocorrelation is found between BUA and BMD.
Velocity Dispersion values in the three directions
are significantly positively correlated to BMD (R2 =0.4, p<10-5 in the axial direction).

Interestingly, negative values of velocity
dispersion were found for 9 sample and directions
for the first time, mostly in the tangential direction
and for mixed microstructure. Negative values
might be explained by interferences of two pulses
propagating at different wave speed in the mixed
microstructure, leading to a “mixed mode”
configuration [4].
Figure 1 shows the relationship between BUA anddispersion measurements for the different directions.
The solid line shows the results predicted using the
Kramers-Kronig relationship [5, 6] which predict a
slope of the dispersion as a function of BUA higher
than what is observed experimentally. These
discrepancies may be due the limited bandwidth [7]and to the interference effects described above.

Dispersion (m/s)

40
30
20
10
0
−10
−20
0

5
10
BUA(dB/cm/MHz)

15

Fig. 1 Dispersion vs BUA values in the range from 3.5
to 4.5 MHz for all directions. Crosses (respectively stars)
correspond to the axial (resp. radial) direction. Fulltriangles correspond to samples of mixed microstructurein the tangential direction and hollow triangles
correspond to other sample in the tangential direction.
The full line shows results obtained using the
Kramers-Kronig relationship.

The present study is the first extensive study of
BUA and dispersion around 4 MHz in cortical bone.
The results obtained in this study compares wellwith results found in the literature in terms of BUA[8-11] [12] and dispersion [8] [10], although muchless samples were considered in these previous
studies.
The dependence of BUA on the direction may be
due to scattering effect, because osteons andlamellae are oriented in the axial direction. The
transmitted wave crosses fewer pores when it
propagates in the axial direction and is therefore
less attenuated. In addition, BUA values obtainedfor each kind of microstructure are similar to therepartition of pores size in each microstructure(8~12µm in plexiform, 20~50µm in Haversian and50~300µm in porotic) which may determine thescattering regime.
Visco-elasticity may also contribute toattenuation in cortical bone. Interstitial tissue
between osteons and lamellae is known to have avisco-elastic behavior (see for instance [13]).
Interstitial tissue is more prominent in Haversian

than in plexiform microstructure which may also
contribute to higher BUA in Haversian
microstructure. In the future, more interest shouldbe placed in assessing the effect of hydroxyapatite

crystallite orientation on BUA and dispersion,as it was done recently for velocity
measurements [14]These promising results show that BUA anddispersion might be complementary parameters toinvestigate cortical bone quality with axial
transmission devices. More details on this work can
be found in [15-17].
Acknowledgment
Part of this study was supported by the Academic
Frontier Research Project on "New frontier ofBiomedical engineering Research" of Doshisha
University. Mami Matsukawa would like to thank the
Bilateral joint projects supported by JSPS and CNRS. .
Magali Sasso would like to thank the University Paris 12-Val de Marne (‘‘Conseil Scientifique’’) for support
during her stay at the Laboratory of UltrasonicElectronics, Doshisha University, Japan.
References[1] Y. Yamato, H. Kataoka, M. Matsukawa, K. Yamazaki,
T. Otani, and A. Nagano, Japanese Journal of Applied
Physics 44 (2005), 4622.
[2] Y. Yamato, M. Matsukawa, T. Otani, K. Yamazaki,
and A. Nagano, Ultrasonics 44 (2006), 233.
[3] P. Droin, G. Berger, and P. Laugier, IEEE
Transactions on Ultrasonics, Ferroelectrics, andFrequency Control 45 (1998), 581.
[4] K. R. Marutyan, M. R. Holland, and J. G. Miller, J
Acoust Soc Am. 120 (2006), EL55.
[5] M. O'Donnell, E. T. Jaynes, and J. G. Miller, J Acoust
Soc Am 63 (1978), 1935.
[6] M. O'Donnell, E. T. Jaynes, and J. G. Miller, J Acoust
Soc Am 69 (1981), 696.
[7] K. R. Waters, M. S. Hughes, G. H. Brandeburger, andJ. G. Miller, J. Acoust. Soc. Am. 108 (2000), 556.
[8] R. S. Lakes, H. S. Yoon, and J. L. Katz, Journal of
Biomedical Engineering 8 (1986), 143.
[9] C. M. Langton, A. V. Ali, C. M. Riggs, J. A. Evans,and W. Bonfield, Clinical Physics and Physiological
Measurement 11 (1990), 243.
[10] S. Lees and D. Z. Klopholz, Ultrasound in Medicine
and Biology 18 (1992), 303.
[11] S. Han, J. Rho, J. Medige, and I. Ziv, Osteoporosis
International 6 (1996), 291.
[12] L. Serpe and J. Rho, Journal of Biomechanics 29(1996), 963.
[13] R. S. Lakes and J. L. Katz, J Biomech 12 (1979),
679.
[14] Y. Yamato, M. Matsukawa, T. Yanagitani, K.
Yamazaki, H. Mizukawa, and A. Nagano, Calcif TissueInt. 82 (2008), 162.
[15] M. Sasso, G. Haïat, Y. Yamato, S. Naili, and M.
Matsukawa, in press, Ultrasound Med Biol (2007).
[16] M. Sasso, G. Haïat, Y. Yamato, S. Naili, and M.
Matsukawa, J Biomech 41 (2008), 347.
[17] G. Haiat, M. Sasso, S. Naili, and M. Matsukawa, J
Acoust Soc Am. (in press).

3P7b-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 461- 462
11-13 November, 2008

Influence of multiple scattering and of absorption on velocity
dispersion in trabecular bone
Guillaume Haïat†1, Alain Lhémery2, Frédéric Padilla3, Pascal Laugier3 and Salah Naili4
CNRS, Université Paris 7, Laboratoire de Recherches Orthopédiques, UMR CNRS 7052 B2OA, 75010
Paris, France, 2 Commissariat à l’énergie Atomique, LIST, Gif-sur-Yvette, France.
3: CNRS, Université Paris 6, Laboratoire d’Imagerie Paramétrique, UMR 7623 15, rue de l’école de4
Médecine 75006 Paris Laboratoire de Biomécanique et Biomatériaux Osteo-Articulaires, UMR

1

CNRS 7052 – Université Paris 12, Créteil, France.
1. Introduction
Quantitative ultrasonic (QUS) techniques are now
widely used clinically for the diagnostics ofosteoporosis. In particular, Speed of Sound (SOS)
measurements are highly correlated with bonemineral density and bone strength for bovine andhuman specimens. Most of the anatomical sites
assessed with QUS techniques are composed oftrabecular bone, which consists in an anisotropic,
heterogeneous and two phase medium made of a
network of interconnected elastic rods or plates (thetrabeculae) filled with a viscous fluid-like medium(the marrow). Despite their routine clinical use, thephysics of ultrasonic propagation through trabecularbone and the mechanisms responsible for thevariation of the ultrasonic velocity with boneproperties still remain unclear.
Of particular interest is the question of velocity
dispersion. Unlike most soft tissues in which thephase velocity has been shown to be an increasing
function of frequency, negative values of thevelocity dispersion have been measured intrabecular bone [1-6] and remain poorly explained
physically.
In the past, numerous aspects of ultrasonic bone
characterization have been investigated and several
theoretical models have been applied to theultrasonic propagation through cancellous bone
including Biot or Schoenberg. Some models
considering the scattering of the ultrasonic wave on
the trabeculae modeled as infinite cylinders havebeen developed assuming independent [7] as wellas multiple scattering [8, 9].
Such approaches led to the prediction of negativeand positive values of the velocity dispersion
according to the microstructure, but the physicaldeterminants of velocity dispersion could not be
estimated. Moreover, a recent work by Marutyan etal. [10] shows that negative value of the dispersion
in trabecular bone can arise from interference
between fast and slow longitudinal wave modes aspredicted by the Biot theory. However, the Biot
theory presents several shortcomings in that it
requires a large number of parameters (tortuosity,-----------------------------------------------------------†:

guillaume.haiat@univ-paris-diderot.fr

permeability, viscous characteristic length, powerindex, etc.) that are not known with accuracy.
Negative velocity dispersion has been previously
predicted by multiple scattering theories to modelcomposite material [11]. However, it has not beenused so far in order to predict and understand suchphenomena in trabecular bone. The aim of thispaper is to propose a model predicting thefrequency dependence of the phase velocity as wellas their physical determinants by considering asimple biphasic description of trabecular bone,where the trabeculae are assumed to be identicaland parallel and by taking into account multiple
scattering
phenomena.
Therefore,a2D
homogenization model accounting for the couplingof absorption and multiple scattering effects is
employed to calculate the dependence of phasevelocity on frequency and bone properties.
2. Theory
The problem of multiple scattering of waves by aset of scatterers is a classical problem of theoreticalphysics, initially solved in the 1940’s [12]. Some ofthese theories were developed in order to describe a
two-phase material composed of oriented fibers in amatrix. Among these theories, the quite recent one
developed by Yang and Mal [13] known as thegeneralized self-consistent method relies on thedescription of the heterogeneous medium as being
constituted of three cylindrical phases. This
three-phase description is combined with theclassical multiple-scattering theory originallyderived by Waterman and Truell [14] for sphericalscatterers and then modified to account for thecylindrical symmetry. The idea of a three-phasemodelling approach is to describe the homogeneous
effective medium by considering three concentric
cylinders.
In this paper, the model developed by Yang and Mal[13] is adapted in order to model trabecular bone asa two-phase medium composed of randomly
distributed elastic infinite cylinders corresponding
to the trabeculae saturated with water (for in vitro
experiments) and to bone marrow (for in vivo
experiments).
Here, the axes of all scatterers are assumed to beperpendicular to the plane of incidence of theultrasonic wave, this situation corresponding to a
2D model.
Bone material properties were taken from theliterature. We have included in our model
absorption phenomena, which was not done in theoriginal model. The attenuation coefficient at 600
kHz in bone and marrow was also taken from theliterature [15]. The frequency dependence of phasevelocity for each medium was obtained by applying
the local Kramers-Kronig relationships [16].
The surrounding medium is an artificial synthetic
medium that represents the overall effective
homogeneous elastic medium to be determined.
Radius a is that of the scatterer and radius b isrelated to the average free path of scattered waves
in water and depends on bone volume fraction(BV/TV) and on a through:aEq. (1)b=
BV / TV

Moreover, the density ρe of the effective medium isa simple function of BV/TV and is given by:ρe = BV/TV ρw+ (1-BV/TV) ρt.
Eq. (2)The computation of phase velocity is performed for
10 values of f between 400 and 800 kHz. The valueof the velocity dispersion is then obtained through aleast square regression analysis of the phasevelocity as a function of the frequency.
3. Results and discussion

Velocity Dispersion (m/s/MHz)

20
Scatterer volume fraction=5%

10
0
−10
−20
−30

Scatterer volume fraction=25%

−40
−50

100

150
200
250
Scatterer diameter (µm)

300

Fig. 1 Simulated velocity dispersion around 600 kHz asa function of BV/TV. The solid and dashed lines
correspond respectively to results obtained with ascatterer diameter of 300 and 75 µm. Black lines
correspond to results obtained by neglecting all
viscoelastic effects; dark grey (respectively ligth grey)lines correspond results obtained by considering
viscoelastic effects in the scatterer only (respectively inthe scatterer and in the matrix).

In order to test and validate the model on a simple
configuration
corresponding
to
the
2D
approximation of our model, the results weresuccessfully compared with the experimental results
obtained by Wear in [17] with trabecularbone-mimicking phantoms [18] (data not shown)..
Figure 1 shows the variation of dispersion as afunction of BV/TV for relatively thin and thickscatterer diameters. The order of magnitude ofvelocity dispersion values spans within the range
obtained experimentally [5]. When considering noabsorption, the velocity dispersion is always
negative. However, when absorption is accounted
for in the trabeculae (dark grey lines), an increaseof dispersion depending on BV/TV is found.
Moreover, taking into account absorption in the
marrow (light grey lines) leads to an increase ofdispersion, which is independent of BV/TV.
Velocity dispersion is a decreasing function of thescatterer diameter due to the increase of thescattering cross section. When absorption is taken
into account, weak (respectively high) scatterer
diameters lead to positive (respectively negative)
dispersion values. Most experimental values ofdispersion are negative, which seems to indicatethat the contribution of scattering phenomena
would be more important than that of viscousabsorption. More details on this work can be foundin Ref. [18].
References[1] K. A. Wear, IEEE Trans. Ultrason. Ferroelect. Freq.
Contr. 48 (2001), 1079.
[2] R. Strelitzki and J. A. Evans, Eur. J. Ultrasound 4(1996), 205.
[3] P. H. F. Nicholson, G. Lowet, C. M. Langton, J.
Dequeker, and G. Van der Perre, Phys Med Biol
41 (1996), 2421.
[4] K. Wear, Ultrasound. Med. Biol. 26 (2000), 641.
[5] P. Droin, G. Berger, and P. Laugier, IEEE Trans.
Ultrason. Ferroelec. Freq. Contr. 45 (1998),
581.
[6] G. Haiat, F. Padilla, R. O. Cleveland, and P. Laugier,IEEE Trans. Ultrason. Ferroelec. Freq. Contr. 53(2006), 39.
[7] K. A. Wear, J. Acoust. Soc. Am. 115 (2004), 66.
[8] F. Luppé, J. M. Conoir, and H. Franklin, J. Acoust.
Soc. Am. 111 (2002), 2573.
[9] F. Luppé, J. M. Conoir, and H. Franklin, J. Acoust.
Soc. Am. 113 (2003), 2889.
[10] K. R. Marutyan, M. R. Holland, and J. G. Miller, J.
Acoust. Soc. Am. 120 (2006), EL55.
[11] V. K. Varadan, Y. Ma, and V. V. Varadan, J. Acoust.
Soc. Am. 80 (1986), 333.
[12] L. L. Foldy, Phys Rev 67 (1945), 1415.
[13] R. B. Yang and A. K. Mal, J. Mech. Phys. Solids 42(1994), 1945.
[14] P. C. Waterman and R. Truell, J. Math. Phys. 2(1961), 512.
[15] S. A. Goss, R. L. Johnston, and F. Dunn, J. Acoust.
Soc Am. 64 (1978), 423.
[16] M. O'Donnell, E. T. Jaynes, and J. G. Miller, J.
Acoust. Soc. Am. 69 (1981), 696.
[17] K. A. Wear, J. Acoust. Soc. Am. 118 (2005), 1186.
[18] G. Haiat, A. Lhémery, F. Renaud, F. Padilla, P.
Laugier, and S. Naili, J Acoust Soc Am (in revision).

3P7b-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 463- 464
11-13 November, 2008

Estimation of in vivo cancellous bone elasticity
in vivo 海綿骨弾性定数の評価
Takahiko Otani1†, Isao Mano2, Toshiyuki Tsujimoto3, Tadahito Yamamoto4,
Ryota Teshima4, and Hiroshi Naka5 (1Facult. Sci. Eng., Doshisha Univ.; 2OYO ElectricCo., Ltd.; 3Horiba, Ltd.; 4Facult. Med., Tottori Univ.; 5Facult. Med., Osaka City Univ.)
大谷隆彦 1‡，真野功 2，辻本敏行 3，山本真人 4，豊島良太 4，中弘志 5 （1 同志社大 理工; 2 応用電機㈱; 3㈱堀場製作所; 4 鳥取大 医; 5 大阪市立大 医）1. Introduction
The primary purpose of measuring bonestatus is to assess fracture risk in medical
examination. However, mechanical or breaking
strength is obtained only by the destructive testing.
The destructive testing is not appropriate for
medical assessment or medical diagnosis. It is
generally agreed that Bone Mineral Density (BMD)or bone mass density is a good predictor of fracturerisk. The effect of decreasing bone density (asymptom of osteoporosis) is greater for cancellous
bone than for dense cortical bone, because
cancellous bone is metabolically more active.
Accordingly, bone density is assessed or measured
at a site with a high volume fraction of cancellous
bone to estimate the onset of osteoporosis. For the
purpose of assessment of bone status or bonequality in a sense of mechanical strength, it is betterto add a mechanical parameter concerning bonequality to the bone density. Mechanical parameters
relating to mechanical strength, ultimate strength,yield strength, and elastic limit, are not obtainable
by nondestructive way. The only obtainable
parameter by nondestructive way is elasticity.
Estimation of in vivo cancellous bone elasticity andthe dependence of elasticity on bone density is
discussed.
2. Methods
In the cancellous bone, two longitudinal
waves, the fast and slow waves, propagate along a
trabecular orientation. The propagation speed offast wave increases with mass density of cancellous
bone and the amplitudes of fast and slow waves
transmitted through cancellous bone depend
considerably and differently on the mass density1-2).
In our previous studies, the propagation process foran ultrasonic wave through in vivo measurementsite containing cancellous bone was formulated forboth fast and slow waves3) and a new ultrasonicbone densitometer, prototype LD-100, has beendeveloped to assess the bone status by measuring-----------------------------------------------------------totani@oyoe.jp

mass density [mg/cm3] and elasticity [GPa] ofcancellous bone on the basis of the fast and slow
waves4). Prototype LD-100 has been aimed to havea function comparative to that of peripheral
quantitative computed tomography (pQCT, amicrofocus X-ray system), and measurement site is
set at the same site of pQCT, at the distal end ofradius, to realize a direct comparison of measured
cancellous bone density between the ultrasonic andradiological methods in the same unit [mg/cm3].
Bone mineral density or bone mass density ofcancellous bone was evaluated by the attenuation oftransmitted slow wave and elasticity of cancellous
bone was evaluated by the propagation speed of fast
wave and the bone mass density. 175 volunteers
from 22 to 87 years old (average age 59.0 years old).
They consisted of 54 men (average age 57.9 years
old) and 121 women (average age 59.5 years old).
After obtained informed consent, all measurements
were carried out.
3. Results and discussion
Each subject was measured by ultrasonicmethod, prototype LD-100 and also by radiologicalmethod, pQCT (Stratec XCT-960). Cancellous bonedensities measured by slow wave attenuation are
shown in Fig.1. Measured densities are expressed inbone mineral density. Measured propagation speedsof fast wave in cancellous bone are shown in Fig.2
as a function of bone volume fraction Vf. According
to measured results in Fig.2, the fast wave speed isapproximately expressed by a linear equation,
except in the vicinity of Vf = 0, as(1)
c4 = m ρ 4 + n= m ( ρb t V f ) + n
where

c4 : propagation speed of fast wave
ρ4 : apparent mass densityρbt : material density of bone tissue(trabecular bone tissue)
Vf : bone volume fraction (BV/TV)
Since the fast wave propagates in trabecular
structure of cancellous bone, the elasticity forCancellous bone is comprised of a trabecular
network with soft tissue (bone marrow) in the porespaces. If the cancellous bone density decreases tozero, the elasticity of cancellous bone (with bonemarrow in situ) should approach to the elasticity ofbone marrow (2.0GPa). Thus, the elasticity Ec ofcancellous bone with bone marrow in situ isexpressed by the sum of the elasticity of trabecular
structure and bone marrow as
2(3)
Ec = ρ bt V f c4 + Ebm 1 − V f

(

)

(

)

= ρ 4 c4 + Ebm (1 − V f )2where Ebm : elasticity of bone marrow
Estimated elasticities of cancellous bone of subjects
are shown in Fig.3. Estimated relation given byeq.(3) is also represented in the figure.
Remarks and summery
1) The bone density and the elasticity of cancellous
bone are evaluated on the basis of clear causality
concerning fast and slow waves.
2) Measured values(a) Bone mass density (or bone mineral density)in [mg/cm3] and bone volume fraction(BV/TV) in [%], which is compatible withmeasured value in [mg/cm3] obtained by the
X-ray CT system.
(b) Elasticity of cancellous bone in [GPa].
Measured in vivo elasticities : 2.2-5.4GPa
average
2.9GPalowest
2.1GPa (BV/TV = 5%)(water
2.2GPa)(bone marrow 2.0GPa)
3) Elasticity of cancellous bone is approximately
expressed by a third degree function of bonedensity. In case bone density decreases to zero,elasticity of cancellous bone with bone marrowin situ approaches to that of bone marrow.
References
1. A. Hosokawa and T. Otani : J. Acoust. Soc. Am. 101(1997) 558.
2. A. Hosokawa and T. Otani : J. Acoust. Soc. Am. 103(1998) 2718.
3. T. Otani,: Jpn. J. Appl. Phys. 44, (2005) 4578.
4. I. Mano, K. Horii, S. Takai, T. Suzaki, H.
Nagaoka and T. Otani,: Jpn. J. Appl. Phys. 45,(2006) 4700.

Bone density [mg/cm3 ] deduced fromthe slow wave level E2 ′/E0 (LD-100)

2

300

200

100

r = 0.85
p value < 0.0001
0
0

100

200

300

400

Bone mineral density [mg/cm3 ]measured by pQCT

Fig.1 Bone density deduced from slow wave leveland bone mineral density measured by pQCT.
Propagation speed offast wave c4 [mm/us] (LD-100)3= α ρ4 + β ρ4 + γ ρ4

400

4

3

2

n
cm
1

0
0

0.1

0.2

0.3

0.4

Bone volume fraction Vf
measured by pQCT
Fig.2 Propagation speed of fast wave andbone volume fraction measured by pQCT.
8Elasticity [GPa] estimated by
fast wave (LD-100)

longitudinal wave is evaluated by the fast wave
speed and the apparent mass density of cancellous
bone. Elasticity E4 of trabecular structure isexpressed by
2(2)
E 4 = ρ 4 c4

6

4

2

0
0

0.1

0.2

0.3

0.4

Bone volume fraction Vf
measured by pQCT
Fig.3 Elasticity corresponding to fast wave andbone volume fraction measured by pQCT.

3P7b-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 465- 466
11-13 November, 2008

Anisotropy of longitudinal ultrasound velocity and
HAp orientation in bovine cortical bone
ウシ皮質骨中の超音波縦波音速の異向性と HAp 結晶配向
Yuichiro Yaoi1†, Kazufumi Yamamoto2, Takahiko Yanagitani3,
Mami Matsukawa1, Kaoru Yamazaki2 and Akira Nagano2(1 Doshisha Univ.; 2Hamamatsu Univ. Sch. Med. ; 3Nagoya Inst. Tech.)
矢追佑一郎 1‡，山本和史 2，柳谷隆彦 3，松川真美 1，山崎薫 2，長野昭 2(1 同志社大; 2 浜松医大 整形外科; 3 名工大)Quantitative ultrasound (QUS) is a good method tomeasure elastic properties of bone, which is
expected to be an innovative technique to evaluatebone quality. One problem of this method is thecomparatively low measurement accuracy, which
seems to come from the complicated wave
properties in bone, due to the multiscale
heterogeneous and anisotropic elasticity. For
example, the cortical bone mainly consists ofhexagonal hydroxyapatite (HAp) crystallites andtype I collagen. Elastic properties of the bone arestrongly affected by the preference of HAp
crystallites, because elastic modulus of HAp
crystallites is more than 80 times larger than that oftype I collagen1). We have investigated the
distribution of ultrasonic longitudinal wave
properties in the cortical part of bovine femur,
considering the microstructure and the HAp
crystallites orientation2) 3). In this study, then, theanisotropy of ultrasound wave velocity (SOS) andthe HAp crystallites orientation are experimentallyinvestigated in detail, using cylindrical specimens
obtained from the bovine cortical bone.

of 1 MHz and amplitude of 50 Vp-p was applied tothe transmitter. The longitudinal wave propagatedthrough water, sample and water. The flattransducer received the wave, and converted it into
the electrical signal. The received signal was
amplified by a 40-dB preamplifier and visualized inan oscilloscope. The measured specimen wasplaced in the focal zone of the sound field. The
direction of the ultrasound incident wave wasperpendicular to the side surface of the cylindrical
specimen. The measurements were done at eachrotation angle of 5 degrees.
proximal

14 mm
[mm]

450 mm

1. Introduction

Pro30

30

Middle

0

Dis30

30
7~12 mm
11 mm

2. Materials and Methods
A left femur was obtained from a 32-month-old
bovine. Three ring-shaped cortical bone samples
were obtained from the mid-shaft. Four cylindrical
specimens (diameter 11mm) were taken from one
ring sample as shown in Fig. 1.
Measurements of longitudinal wave speeds were
performed using a conventional ultrasonic pulse
technique as shown in Fig. 2. A PVDF focus
transmitter (diameter 20 mm, focal length 40 mm)
and a flat PVDF receiver (diameter 10 mm) wereused in this experiment. The beam width at the half
maximum values of the wave amplitude wasapproximately 1.5 mm at the focal point. BothPVDF transducers were mounted coaxially with
distance of 60 mm in degassed water at 22.0±1.0 ℃.
A single sinusoidal signal with a center frequency-----------------------------------------------------------yuichiro_y0306@hotmail.co.jp

distalFig. 1 Specimen.

Pre-amp.

θ

Power-amp.

90°
0°

180°
270°

ReceiverOscilloscope

Transmitter

Function generator

Fig. 2 Ultrasound measurement system.

The crystalline orientation of the sample wasdetermined by XRD pole figure analysis (Philips,
X-Pert Pro MRD). X-ray source (Cu-Kα, generated
at a tube conditions of 45 kV and 40 mA) irradiatedthe sample surface through the parallel beam optics
with 0.3 mm x 3 mm slit. The X-ray irradiatedarea was always smaller than the sample surface
area in this optics.

0 [degree]

270

3800 90
[m/s]

3400

3. Results and Discussions

180
Fig. 3 Anisotropy of ultrasound velocity in the anterior
part of the middle sample. Velocity difference from3100 m/s was adopted to emphasize the anisotropy.

Anterior

MedialAnterior

MedialLateralproximal

0
4000
315

0
4000

45

315

3800

45
3800

3600

3600

3400

3400

3200

3200

270

90

270

90

3200 3400 3600 3800 4000

3200 3400 36 00 38 00 4000

distal
225

135

225

Posterior

Posterior

LateralMedial
0

0

4000

4000

4. Conclusion

Anterior

MedialAnterior

Lateral

1 35

180

180

315

315

45

45

3800

3800

3600

3600

3400

3400
3200

3200
270

90

270

90
3200 340 0 3600 3800 4000

3200 3400 3600 3800 400 0

We have investigated the anisotropy of ultrasoundwave velocity and the HAp crystallites orientation.
We have found that the directions of the fastest
velocity and the c-axis of the HAp crystallites
orientation are a little inclined from the bone axis.

Posterior

Posterior

LateralFigure 3 shows the velocity data of a specimen
obtained from the anterior part of the middle
sample. The 0 degree indicates the axial direction
and the 90 degree indicates the tangential direction.
Velocity changed due to the rotation angle. Four
specimens in the same ring showed similartendency of velocity, which were higher in the axial
direction. However, the direction where the fastest
wave velocity was observed was inclined 5 to 10
degrees from the axial direction. Figure 4 shows
the anisotropy of ultrasound wave velocity at eachpart in the middle specimens. Figure 5 shows(0002) pole figure measured from the anterior
specimen. From the pole-figure of X-ray diffraction
analysis, the highly concentrated pole was clearlyobserved. This pole concentration indicates that the
crystalline c-axes are oriented to the similar
direction. We also found the small tilt of c-axis
direction from the bone axis, which was inagreement of the velocity data. There is apossibility that the small tilt of the direction of thefastest wave seems to be dependent of the HAp
crystallites orientation.

225

1 35

1 80

225

1 35

180

Fig. 4 Anisotropy of ultrasound wave velocity inthe middle sample of bovine femur.

Acknowledgment
Part of this work was supported by a Grant-in-Aid
for Scientific Research (B) from JSPS and thebilateral joint project between JSPS and CNRS.
References
1. R. S. Gilmore et. al.: J.Mater.Sci. 17 (1982) 1131.
2. Y. Yamato et. al.: Calcif. Tissue Int. 82 (2008)
162.
3. K. Yamamoto et. al.: Jpn. J. Appl. Phys. 47(2008) 4096.
Fig. 5 (0002) pole figure in the anterior part of the
middle sample, with the explanation of angles.

3P7b-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 467- 468
11-13 November, 2008

The effect of soft tissue on the ultrasonic wave
propagation in cancellous bone
海綿骨中の軟組織が超音波の伝搬に与える影響
Takashi Saeki 1†, Tomohiro Kubo1, Mami Matsukawa1 and Yoshiki Nagatani2(1 Doshisha Univ.; 2Kobe City College of Technology)
佐伯崇 1‡，久保智宏 1，松川真美 1 ,長谷芳樹 2（1 同志社大学; 2 神戸市立工業高等専門学校）

1. Introduction
Longitudinal ultrasonic wave propagating incancellous bone separates into two waves, fast andslow waves. The fast wave mainly propagates in thetrabeculae bone. BV/TV (bone volume fraction)
and anisotropy of cancellous bone have strong
effects on the propagation phenomena of fast wave.
On the other hand, the slow wave mainly
propagates in the soft tissue. Several studies havebeen performed to understand the nature of thesewave propagation phenomena [1-2]. Most of theformer investigations were in vitro studies using thecancellous bone filled with water. However, for invivo application of ultrasonic technique, it isnecessary to study the effect of actual soft tissue(marrow) among cancellous bone upon the wave
propagation.
In this study, then, we have investigated theultrasonic properties of bone marrow, whose
ultrasonic properties have not been evaluatedprecisely. Considering the properties, we haveinvestigated wave propagation in the cancellous
bone filled with the marrow, especially focusing on
the studies through both experiment and the FDTD
simulation.

In addition, as shown in Fig.1b, we removed
the marrow from the femoral diaphysis to measureultrasonic properties.
3. Ultrasonic measurements
At first, we have measured the ultrasonicproperties of the bone marrow with a conventional
ultrasonic pulse technique. By changing the lengthof the sample marrow, we obtained velocity andattenuation in the temperature range from 20 ℃ to
39 ℃.
We next measured the cancellous bone filledwith marrow or water. The measurements were
performed using an acoustic tube shown in Fig. 2.
This acoustic tube was filled with water.
Here, we used self made transducers using
PVDF film (Toray, thickness 40 µm). The applied
electrical signal was 1 cycle of sinusoidal wave at 1
MHz. The received signals were amplified 40dB by
a preamplifier (BX-31, NF Corporation) andmeasured by an oscilloscope (TDS5000 Tektronix
Japan, Ltd.). Water and specimen were deaerated ina vacuum camber for 2 hours before measurement.
30mm
60mm
20mm
20mm
PVDF
Transducer

PVDF
film

Cancellous
bone

Water

Fig.2 Configuration of an acoustic tube

(a)

(b)

Fig.1 Cancellous bone in the epiphysis andbone marrow obtained from the diaphysis.
2. Specimen

The bone mainly consists of cortical bone,
cancellous bone and bone marrow. Cancellous bone
is filled with marrow. We obtained specimens fromleft 25-month-old bovine femur. As shown in Fig.1a,bone marrow fills the pores among trabecular
structure. The specimen size was 20×20×9 mm.
saeki@usl.doshisha.ac.jp

4. FDTD Simulation
The followings are the governing equations
for the 3-dimensional elastic FDTD method for theisotropic medium related to the x direction [3]:
∂v y
∂σ xx
∂v
∂v
+λ z
= ( λ + 2µ ) x + λ
∂y
∂z
∂t
∂x

 ∂v
∂v 
= µ x + x ∂σt∂ x 
 y∂v x 1  ∂σ xx ∂σ xy ∂σ zx 
=
+
+
∂t
∂y
∂ z ρ  ∂ x
∂σ xy

(1)
(2)
(3)

trabeculae and soft tissue, which cannot be
considered in the FDTD simulation.

Wave velocity [m/s]We simulated wave propagation in thecancellous bone using X-ray CT image of an actual
cancellous bone. Figure 5 shows an example of theimage obtained by X ray CT (SMX-160CT-SV3
Shimadzu, Kyoto). The spatial resolution was 60.7
µm. Here, the total simulation field was 21.6×21.6
×17.2 mm. The size of cancellous bone was 21.0
× 21.0 × 9.0 mm. The time increment for thesimulation was 5 ns. As shown in Fig.6, the initial
particle velocity was given at the top of thesimulation model assuming a plane transmitter. The
experimentally measured waveform was used forthe initial wave.

1600
1550
1500
1450
1400
1350
1300

Sample 1
Sample 2

20

25

30

35

40

45

Temperature [℃]

Amplitude [mV]Fig. 7 Temperature dependence of observed wave
velocity.

Fig.5 X-ray CT image of cancellous bone.

Filled with WATER

10mV
Filled with MARROW

30

32

34

36

38

40

42

-6

44x10

Time [sec]yxTransmitter
Water

z

Fig. 8 Experimentally observed waveform passed
through specimen.

Water or Marrow

Cancellous bone

Filled with WATER

Amplitude [A.U]

Absoption aria

Filled with MARROW

Receiver0

Fig.6

FDTD simulation model.

5. Results and discussions
We have measured bone marrow samples
obtained from the different bovine femora. The
averaged wave velocity of the marrow was almost
1440m/s at 36 oC. Figure 7 shows the temperaturedependence of wave velocity in two samples. The
velocity values were similar with the reported dataof El-Sariti et.al. One interesting result is thecomparatively low velocity in the marrow. The
attenuation in the bone marrow was also measured.
Next, we have compared the wave
propagation in the cancellous bone fromexperimental and simulation studies. In both results,
we can confirm the clear separation of incident
wave to the fast and slow waves. The amplitudes of
the waves were dramatically changed in theexperiments, especially in case of bone filled withbone marrow. One reason for this seems to comefrom the effect of frictional loss at the interface of

2

4

6

8
Time [sec]

10

12

-6

14x10

Fig.9 Simulated waveform passed through thespecimen.
6. Conclusion

Ultrasonic wave propagation in the bovine
cancellous bone was investigated, considering theultrasonic properties in bone marrow. From thecomparison between experiments and simulations,the possible strong effect of frictional loss at thesolid bone- soft tissue interfaces was pointed.

References
1. A. Hosokawa, and T. Otani, J. Acoust. Soc. Am,
101 (1997) 558.
2. A. Hosokawa, et.al., Jpn. J. Appl. Phys., 36(1997) 3233.
3. Y. Nagatani et.al., Jpn. J. Appl., Phy., 44 (2006)
4622.
4. A. El-Sariti et.al., Ultra. Med. Bio. 32 (2006)985.

3P7b-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 469- 470
11-13 November, 2008

Influence of Trabecular Elements on Fast and Slow
Wave Propagations in Oblique Directions to Layers of aStratified Trabecular Phantom
層状構造海綿骨ファントム中を斜方向伝搬する高速波・低速波
における骨梁要素の影響
Atsushi Hosokawa† (Dept. Elect. & Comp. Eng., Akashi Nat. Coll. Tech.)細川篤† （明石高専 電気情報）

2. Stratified trabecular phantoms
Based on a stratified model composed ofperiodically alternating solid and fluid layers,3) thestratified trabecular phantom was previously
developed.2) In this trabecular phantom, as shown in
Fig. 1, the minor trabecular rods were arranged
perpendicular to the major trabecular plates. As the
purpose of this study was to investigate theinfluence of trabecular elements (but not material
properties), the practical phantom was generatedusing brass plates and cylindrical rods. The spaces
between the trabecular (brass) plates were filledwith degassed water as substitute for bone marrow.
Assuming bovine cancellous bone, the plate-----------------------------------------------------------hosokawa＠akashi.ac.jp

5 mm

5

m

m

1 mm

Trabecular rodmm

Ultrasound characteristics in bone depend on
not only the material but also structural properties.
Because the ultrasound waves propagating in bonereflect these properties mixedly, estimating the boneproperties from their parameters is very difficult. In
order to realize accurate bone assessment using
ultrasound techniques, therefore, the influence ofbone structure must be clarified. In particular,
cancellous bone can largely affect the propagationof ultrasound waves owing to complexity of theinnner trabecular structure. The macroscopic
trabecular orientation is closely related to theultrasound propagation through cancellous bone,
and a unique phenomenon that two longitudinal
waves, called as “fast and slow waves”, propagate
in the oriented trabecular direction can beobserved.1) However, the influence of trabecular
microstructure on the fast and slow waves is not
sufficiently clear.
In the previous study,2) the influence of minor
trabecular rods on the fast and slow wave properties
was investigated by using stratified trabecularphantoms. In this study, the influence on theseproperties in oblique directions to the stratified
layers was experimentally investigated.

Trabecular plate10

1. Introduction

0.2 mm1 mm

Fig. 1 Geometry of a stratified trabecular phantom.

thickness and space were determined to be 0.2 and
1 mm, respectively. The final thickness of thephantom was 10 mm. For comparison, the phantom
without the rods was also generated.
3. Calculating method of propagation speed4)
At oblique incidence on the surface of a solid
specimen in a fluid, an ultrasound wave is refracted
according to Snell’s law. If the time difference of
the ultrasound wave with and without the specimen
is Δt, the wave speed in the solid vs is given by
−1

2
2
⎤
⎛ v s ⎞ ⎡ ⎛ v f Δt ⎞⎛ v Δt ⎞⎜ ⎟ = ⎢1 + ⎜⎟ − 2⎜ f ⎟ cosθ i ⎥ , (1)⎜ d ⎟⎜v ⎟ ⎢ ⎜ d ⎟⎥⎦⎠⎝⎠⎝ f ⎠ ⎣ ⎝where vf is the speed in the fluid, d is the specimen
thickness, and θi is the incident angle. The refracted
angle θr, that is the propagation angle in thespecimen to the thickness direction, is given bysinθ itanθ r =.
(2)cosθ i − (v f Δt d )Speed (m/s)

Amplitude (dB)

4000

0
-4
-8

Without rods
With rods

-12
0

10

20
30
40
50
Angle of propagation (°)

3500
3000
2500
2000
1500

60

Without rods
With rods
010(a) Fast wave

20
30
40
50
Angle of propagation (°)60(a) Fast wave

Speed (m/s)

Amplitude (dB)

2000
0
-4
-8

-12
0

10

20
30
40
50
Angle of propagation (°)

60

1800
1600
1400
1200
1000

0

10

20
30
40
50
Angle of propagation (°)60(b) Slow wave(b) Slow wave

Fig. 2 Fast and slow wave amplitudes in stratifiedtrabecular phantoms without and with trabecular rods
vs. propagation angle to trabecular plates.

Fig. 3 Fast and slow wave speeds in stratifiedtrabecular phantoms without and with trabecular rods
vs. propagation angle to trabecular plates.

4. Experimental results

5. Conclusions

Fast and slow waves propagating throughstratified trabecular phantoms without and withtrabecular rods were experimentally observed inwater. The trabecular phantoms were rotated on theaxis parallel to the trabecular plates andperpendicular to the trabecular rods, as shown in
Fig. 1. For each wave, the peak-to-peak amplitude
and the propagation speed were measured as afunction of the propagation angle to the trabecularplates.
Firstly, the measured results of the fast and slow
wave amplitudes are shown in Fig. 2. Similarly
with the previous results,2) it can be observed thatboth amplitudes are attenuated by the influence ofthe trabecular rods. This influence on the fast wave
amplitude is not significantly changed with the
propagation angle, whereas the slow wave
amplitude is less influenced at higher propagation
angles. Next, the measured speeds of the fast andslow waves are shown in Fig. 3. The fast wave
speed in the trabecular phantom with the trabecularrods is slightly slower than that without thetrabecular rods. This difference seems to disappear
at higher propagation angles. The obvious
difference in the slow wave speed, on the other
hand, cannot be found.

The influence of minor trabecular rods was
experimentally investigated for the fast and slow
wave propagations at oblique angles to the layers of
the stratified trabecular phantom. The experimental
results showed that the influence on the slow wave
amplitude largely depended on the propagation
angle, that is the propagation direction.
Acknowledgment
This study was supported by a Grant-in-Aid forYoung Scientists (B) (19700393) from MEXT, andin part, by a Grant-in-Aid for Scientific Research(B) (19360189) from JSPS, by the Academic
Frontier Research Project on “New Frontier ofBiomedical Engineering Research” of Doshisha
University and MEXT, and by JSPS and CNRS
under the Japan-France Research Cooperative
Program.
References
1. A. Hosokawa and T. Otani: J. Acoust. Soc. Am.
101 (1997) 558.
2. A. Hosokawa: Jpn. J. Appl. Phys. 47 (2008)
4170.
3. M. Schoenberg: Wave Motion 6 (1984) 303.
4. R. E. Smith: J. Appl. Phys. 43 (1972) 2555.

3P7b-20

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 471- 472
11-13 November, 2008

Introduction of “Digital Elastic Model of Human Body”
for 3-D FDTD Simulation- Elastic Wave Propagation in Human Body 体内音場解析のための“ディジタル人体弾性モデル”実現に向けてYoshiki Nagatani1‡, Atsushi Hosokawa2 , Takefumi Sakaguchi 3 , Mami Matsukawa 4,
and Yoshiaki Watanabe 4 (1 Kobe City College of Technology; 2 Akashi National
College of Technology; 3 Nara Medical University; 4 Doshisha University)‡

長谷芳樹 1 ，細川篤 2，阪口剛史 3，松川真美 4，渡辺好章 4 （1 神戸市立工業高等専門学校; 2 国立
明石工業高等専門学校; 3 奈良県立医科大学; 4 同志社大学）

1. Backgrounds and Objectives
There are many previous studies about
numerical simulations focusing on specific area of
human body. As comparative studies between
simulations and experimental measurements, ourgroup has also worked on behaviours of ultrasonicwaves in cortical bones, cancellous bones, bonemarrows [1-6], and sound distributions in humanheads [7,8]. However, the simulation technique ofelastic wave propagation including entire humanbody is not established yet. The development ofprecise and accurate “Digital Elastic Model of
Human Body” would be an useful tool in medical,
welfare, and engineering fields: e.g. giving us new
point of view and validating safeness on developing
new medical equipments, diagnosis simulators foryoung doctors etc.
As a preliminary work, therefore, weconstructed the elastic model of entire human bodyfor three-dimensional simulation of wave
propagation.

3. Simulation Technique: Elastic FDTD Method
In this study, the elastic three-dimensional
finite-difference time-domain (FDTD) method was-----------------------------------------------------------nagatani@kobe-kosen.ac.jp

Figure 1 Projected figures of three-dimensional“Digital Elastic Model of Human Body.”
3

400x10Stress [Pa]2. Simulation Model: Digital Elastic Body
As a model, the make data in the “Realistic
High-Resolution Whole-Body Voxel Models”
constructed by Nagaoka et al. was used [9]. The
model describes consisting tissues of normal
Japanese person with the resolution of 2 mm.
Using the model, elastic properties of thetissues are assigned to water, fat, cortical bone,bone marrow, and air. The elastic coefficients andattenuation of cortical bone and bone marrow used
are experimentally measured values [4,6]. The
bottoms of both feet are assumed to be immersed inwater. Figures 1(a)(b) show the projected figures ofdensity distribution of 3-D “Digital Elastic Modelof Human Body ” model. The brighter area indicates
the tissue with higher density.

300
200
100
0
0

100

200

300

400

Time [s]600x10-6

Figure 2: Initial normal stress put into square surface atthe bottom of right heel.

used. In order to reflect the absorption effect, thevalues of the normal and shear stresses areattenuated in each calculation step of propagation.
The frequency dispersion of attenuation was notconsidered [5]. In this simulation, the elastic
anisotropy of the solid portion was not considered.
The stress and particle velocity were calculated

alternately both in the spatial and time domains,which was called “the leapfrog method [10].” Theapplicability of the program used has been
confirmed in our previous studies [1,2].
Figure 2 shows the initial stress, a quarter cycleof a sinusoidal wave with Hanning window. It wasapplied to the square surface of 40×40 mm at thebottom of right heel shown in Figs. 1(a)(b). One
step in walking movement of a person of 65 kg in
weight was assumed.
4. Results and Discussions
Figures 3(a)(b)(c) show the screenshots of thenormal stresses on the diagonal surface shown in
Fig. 1(a) as a dotted line, which includes tibia andfemur. Figure 3(c) shows the separation of single
wave into several parts.
Figure 4 shows the received waveform at point
C in Fig. 3(a) which is inside the distal end of thefemur. The first waves with small amplitude may
have passed through solid part of the tibia. After thewaves, multiple scattered waves can be seen.
The changes of peak amplitudes from point A to
D are shown in Fig. 5. The decrease of peak
amplitude may be caused by the multiple reflections
caused by the complex structure of bone. It should
be checked precisely in the future work.

Figure 3: Screenshots of normal stresses in simulation
model at each moment.

Stress [Pa]80

5. Conclusion
Using the “Digital Elastic Model of Human
Body”, the capability of elastic wave simulation
inside human body was confirmed. The multiple
reflected waves was seen while its propagation inhuman leg model.

40
0
-40
-80
0

100

200

300

-6

400

600x10Time [s]Acknowledgment
This study was supported by the Grant-in-Aid
for Young Scientists (B) (20791218) of the Ministryof Education, Culture, Sports, Science andTechnology. This study was partly supported bybilateral joint project between JSPS and CNRS, in
addition to the Academic Research Frontier projectof Doshisha University and Ministry of Education,
Culture, Sports, Science and technology in Japan.

Peak Amplitude of Stress [Pa]Figure 4: Received waveform at point C.

References

Figure 5: The changes of peak amplitudes from point A to D.

1.

2.
3.
4.

5.

Y. Nagatani, H. Imaizumi, T. Fukuda, M. Matsukawa, Y.
Watanabe, and T. Otani, Jpn. J. Appl. Phys., Vol. 45
No.9A (2006) 7186-7190.
Y. Nagatani, K. Mizuno, T. Saeki, M. Matsukawa, T.
Sakaguchi, and H. Hosoi, Ultrasonics (2008). [in press]
A. Hosokawa, Jpn. J. Appl. Phys., Vol. 47 No.5A(2008) 4170-4175.
Y. Yamato, M. Matsukawa, T. Yanagitani, K. Yamazaki,
H. Mizukawa, and A. Nagano, Calcified Tissue
International, 82, No.2 (2008) 162-169.
K. Yamamoto, Y. Yaoi, Y. Yamato, T. Yanagitani, M.
Matsukawa, and K. Yamazaki, Jpn. J. Appl. Phys.,Vol.47, No.5 (2008) 4096-4100.

6.

A
1000

BC

100

D
10
0

200

400

600

Distance from Sound Source [mm]800T. Saeki, M. Matsukawa, and Y. Nagatani, IEICE
Technical Report, US2008-23 (2008) 5-9.
7. T. Sakaguchi, T. Hirano, Y. Watanabe, T. Nishimura, H.
Hosoi, S. Imaizumi, S. Nakagawa, and M. Tonoike, Jpn.
J. Appl. Phys., Vol. 41 No.5A (2002) 3604-3608.
8. Y. Tanikaga, T. Sakaguchi, and Y. Watanabe,
Proceedings of Forum Acusticum, Sevilla (2002).
9. T. Nagaoka, S. Watanabe, K. Sakurai, E. Kunieda, S.
Watanabe, M. Taki, and Y. Yamanaka, Physics in
Medicine and Biology, Vol.49 (2004) 1-15.
10. K. S. Yee, IEEE Transactions on Antenna andPropagation, AP-14, No. 3 (1966) 302-307.

3P8-11

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 473- 474
11-13 November, 2008

A Study on Structure of Joined Surfaces on Ultrasonic Joining of Au
by use of Surface Acoustic Wave Device
弾性表面波素子による金接合における接合状態の検討
Kengo Naruse†1, Kiyomi Mori2 and Yuji Watanabe2*(Seidensha Electronics Co., Ltd1, Takushoku Univ., Faculty of Engineering2)
1

2

成瀬健悟† ，森きよみ ，渡辺裕二

1. Introduction
We are studying the ultrasonic joining of Flip-chiptype package of IC by use of surface acoustic wave
(SAW) device.1),2) In the previous study, we carriedout ultrasonic gold foil (Au:99.95%) joining byusing a SAW device at 2.50 MHz. As the result, we
confirmed that the SAW joining avoids damage ofjoined specimens and it has wider joining space at
higher frequency. In addition, we use the SAW
device of standing wave type for joining of Au.
Therefor, we consider that joined specimens are
influenced by the wavelength of SAW propagation,
and we assume that it is joined at loop points ofstanding wave of SAW. In this paper, we describe
the structure of joined surfaces and distribution ofjoined parts on the ultrasonic joining of Au foil.

2*（精電舎電子工業(株)1, 拓殖大学 工学部 2）

rod is supplied to the specimens being joined,
which are put on the SAW device. In addition,
polytetrafluoroetylene (PTFE) film and polyimide(PI) film are placed between a steel rod and the
SAW device in order to protect heat conduction to
the steel rod. The films are also used as like as acushion to supply static pressure to Au foil
uniformly.
For the excitation of SAW during the joining, we
use gated waves with 2.422 MHz of carrier
frequency, 0.5 ms of duration time and 0.5 ms ofinterval time. The signal is used in order to avoid
destruction of the substrate by heating.
IDT

2. Construction of the SAW joining system
Figure 1 illustrates the SAW device that is used inthis study. The substrate of the SAW device is
128°-rotated Y-cut X-propagating LiNbO3 and thedimensions of the substrate are a length of 30 mm, awidth of 90 mm and a thickness of 10 mm. Using
the substrate, we designed a 2.5 MHz SAW
resonator.3),4) Since the acoustic velocity of the
SAW of the substrate is 4000 m/s, one wavelengthis 1.6 mm. Therefore, the width of every electrodefinger and the gap width between electrode fingers
were both designed as 0.4 mm. In addition, we
designed the apertures to be 15.2 mm and the lengthof propagation path to be 9.2 mm, so we obtained
15.2×9.2 mm2 as a joining area. Moreover, wearranged two sets of inter digital transducer (IDT)
and one set of reflector set on the both end on thesubstrate. The electrical power was supplied by apower amplifier. The practical natural frequency of
the SAW device fabricated was 2.422 MHz whenaluminum was vapor-deposited for the electrodes.
Figure 1(a) shows the top view of the SAW
device. As shown in the figure, vibration velocity at
the measuring point was monitored by using a laser
Doppler vibrometer. Figure 1(b) shows the sideview of the SAW device. As shown in Fig. 1(b),static pressure induced by a dead load from a steel-----------------------------------------------------------*E-mail address: u2watana@es.takushoku-u.ac.jp

Measuring point ofvibration velocity
Width of inter-digital electrode: 0.4 mm
Aperture length: 15.2 mm
IDT: 10pairs×4 Reflector: 4pairs×2
Joining space: 9.2 mm×15.2 mm

Reflector

Joining space(a)
PTFE film
Steel rodt=0.3 mm
φ5.0 mm
PI film
Au foilt=0.125mm
t=0.05 mm×2
128°Ycut X-LiNbO3 t=10mm(b)
Fig.1. Schematic diagram of construction of SAW joining
system. (a) Top view and (b) Side view (t: thickness
φ: diameter)

3. Result of Microscope Observation of Structureof Joined Surfaces

Material characteristics of Au foil are shown in
Table 1. Conditions of SAW joining are shown in
Table 2. Here, two pieces of Au specimens areoverlapped for 3.2 mm. It is equivalent to two
wavelengths of SAW. Thin PI films are put between
the specimens and electrodes in order to makeisolation. And we did the tensile test of the joined
specimens, which are joined under the conditions ofTable 2. For the fractured specimens, we observed

Table1. Characteristics of Au foil.
Material
Melting point(℃)
Material strength(MPa)Material size(mm)Au foil(99.95%)
1337
130.3(99.99%)5)
10×2×0.05

Table2. Conditions of SAW joining.
Specimens
Frequency of SAW joining
Area of joined part(mm2)Vibration velocity(m/s)
Supplied voltage(Vp-p)
Static pressure(MPa)Au foil(99.95%)
Thickness 0.05 mm
Two sheets piled
2.422 MHz
2×3.2
1.7
200
22.0

the fractured surfaces by using a scanning electron
microscope (SEM). The results are shown in Figs.
2(a) – 2(e).
Figure 2(a) shows the surface of Au foil. Figures
2(b) and 2(c) show the fractured surfaces of joined
part. By comparing with Fig. 2(a), we can see
roughness on the surfaces in Fig. 2(b) and 2(c).The
roughness means that the specimens were joined atthese areas. Moreover, roughness can be seen on thewhole surface. Therefore, we understand that joinedpart is not joined only at loop point of the standing
wave of SAW.
Moreover, we can see that the roughness near thecenter of a joined surface of the specimen is large
and deep. On the other hand, the roughness on thecircumference of it is small. The expanded view ofroughness in the circle A and circle B of Fig. 2(b)are shown in Figs. 2(d) and 2(e). From the figures,
we can clearly see the difference in the size ofroughness. Therefore, we can conclude that thejoint strength near a center is strong and thecircumference is weak. On the reason, we guessthat the center of the joining area is joined first bycontact pressure. Therefore, the other area can not
be joined well, because relative motion between
upper and lower film is very low. As the result, it isdifficult to remove oxidized layer and contaminantof the joined surface by ultrasonic vibration. The
fact shows that the static pressure is not supplied tothe specimen uniformly.
4. Conclusions
The structure of joined surfaces on ultrasonic joiningof Au foil by SAW device was studied. As the result,
we confirmed that the distribution of joined part isirrelevant to the wavelength. Furthermore, we guessthat static pressure is not supplied uniformly. As thenext step, we will study on relationship between
distribution of static pressure and joined part.
Acknowledgment
This study was supported by Mr. K. Asakura of: 500μm(a) Surface of Au foil.
The center of joined surface

BA: 500μm(b) The joined surface of the foil of SAW device side.
The center of joined surface: 500μm(c) The joined surface of the foil of pressed side.

: 50μm(d) The expanded view in circle A of Fig. 2(b).

: 50μm(e) The expanded view in circle B of Fig. 2(b).
Fig.2. Observation of surface of specimens by SEM.

Takushoku Univ., Faculty of Engineering.
References
1. K. Naruse, K. Mori and Y. Watanabe：Jpn. J. Appl. Phys. Vol.47(2008) pp.4305-4308
2. K. Naruse, K. Mori and Y. Watanabe：Proc. Symp. Ultrason.
Electron., Vol.28,(2007)pp345-346.
3. T. Kojima: Doctoral Dissertation, Tohoku Univ. 1988 [in Japanese]
4. J. S. P. S. Surface Acoustic Wave 150th Committee: Surface
Acoustic Wave Technology Handbook (Ohmsha, 1991), p.161 [inJapanese].
5. The Japan Institute of Metals ”Metals data book” p.165 [in Japanese].

3P8-12

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 475- 476
11-13 November, 2008

Study on the sound source and the reflector to generatestrong acoustic field for levitation
超音波浮揚における強力音場生成のための音源および反射板の検討
Teruyuki Kozuka†, Kyuichi Yasui, Toru Tuziuti, Judy Lee, Atsuya Towata and Yasuo
Iida (National Institute of Advanced Industrial Science and Technology (AIST))
小塚晃透‡，安井久一，辻内亨，ジュディー・リー，砥綿篤哉，飯田康夫 （産総研）

1. Introduction
Using a standing wave field generated
between a sound source and a reflector, it ispossible to trap small objects at nodes of the soundpressure distribution in air. In order to trap andmanipulate object stably, the force should be strong
enough.
In the previous paper, higher sound pressure
in a standing wave field was achieved using aconcaved reflector than that using a flat one[1]. In
the present paper, a sound field was generated undera flat or concave reflector, and the sound field has
been studied both by experimental measurement
and numerical calculation. The calculated result
agrees well with the experimental data. In the best
condition, a steel ball of 2.0 mm in diameter was
levitated in air.
2. Calculation of the sound fieldA standing wave field was generated between
a sound source and a reflector in air. The soundsource is a cylindrical bolted Langevin typetransducer with a horn of 20 mm, 25 mm or 30 mm
in diameter, and the frequency is 28.0kHz. The
entire surface vibrated equally in phase with aconstant displacement amplitude of 30 μmp-p for all
the horns. The reflector is circular glass plate of 45mm in diameter and the surface is flat or concave.
The focal length of concaved reflector is 51.9 mm
or 77.85 mm. The reflector was parallel to thesound source and placed at 52 mm from the soundsource. The sound speed c0 is 344.0 m/s, the density
ρ0 is 1.2 kg/m3.
The direct sound pressure pd from the soundsource surface F0 is calculated by the Rayleigh’s
formula.

pd = jexp(− jkr0 )ρ 0c0v0
exp( jωt )∫∫
dF0
F
λ
r0
,
0

(1)

-----------------------------------------------------------kozuka-t@aist.go.jp(a) F/20(b) F/25(d) C/20(e) C/25(c) F/30(f) C/30

Fig.1 Calculated sound pressure distribution.
F: Flat reflector, C: Concaved reflector, /20,
/25, /30: Sound source diameter [mm].
where v0 is velocity of a vibrating plate at the soundsource, λ is wave length, ω is angular frequency, t is
time, k is wave number and r0 is the distance
between an arbitrary point on F0 and theobservation point.
When there is an object in the sound field, thereflected waves are generated from the object. In
the present case, there is a reflector in front of thesound source. The reflected sound pressure from thereflector is calculated by integrating the original
sound velocity at the reflector surface F1. Moreover,the second reflected wave on F0 and the thirdreflected wave on F1 are calculated by the similar
equations. The sound pressure distribution on thestanding wave field is calculated by adding thesound pressures. Figure 1 shows the calculated totalsound pressure with a flat or concave reflector forvarious sound source diameters. The focal length ofthe concaved reflector is 51.90 mm. When thesound source diameter is larger, the sound pressure
is higher. With the concave reflector, the soundpressure is higher than that with a flat one.

20mm

The particle in the sound field is forced fromthe anti-node to the node. According to Nyborg and
Gor’kov, the force acting on a small sphere due toradiation pressure can be given by the following
equation, provided the radius a of the sphere issufficiently small compared to the wave length λ:[F = V D∇ ek − (1 − γ )∇ e p

]

0.5

25mm
30mm

0

(a) with a flat reflector.

-0.5
0

(2)

Where V=(4/3)πa , D=3(ρs-ρ0)/(2 ρs+ρ0), <ek> and<ep> are the time averaged kinetic energy andpotential energy of sound acting on the small sphere,
respectively.
Figure 2 shows calculated force on a particle
along the sound beam axis. The particle is made ofsteel (a=1.0 mm, ρ=7874 kg/m3). The force isstronger when the sound source diameter is larger.
The local maximum force in the 3rd cycle from thesound source are 0.15 mN, 0.30 mN and 0.39 mN
for the sound sources of φ20 mm, φ25 mm or φ30mm in diameter, respectively, when the reflector isconcave with 51.9 mm in focal length. When thereflector is concave, the force is higher than that fora flat reflector. When the sound source diameter is
25 mm, the force is 0.04 mN, 0.30 mN or 0.23 mN
with the reflector of flat, concaved with 51.9 mm or
77.85 mm focal length, respectively.

10
20
30
40
Distance from the sound source. [mm]

50

0.5

3

0

-0.5

(b)
with a concave reflector(focal length 51.9mm).
0

10
20
30
40
Distance from the sound source. [mm]

0.5

0
(c)
with a concave reflector(focal length 77.8mm).

-0.5
0The experimental setup is the same as that of
the calculation except that the pin-hole was openedat the center of the reflector and that a thin wire wasthrough the hole. The wire was jointed to a steel
ball and a weighting machine. It measured the steel
ball weigth along the sound beam axis in thestanding wave field. Figure 3 shows the result of
measurement for about 22 mm from the soundsource. The steel ball weight is 33 mg withoutsound, and the value -33 mg means that it islevitated. The maximum weight in the 3rd cycle are
28 mg, 70 mg and 65 mg which corresponds to theforce of 0.15 mN, 0.30 mN and 0.39 mN, when thesound source is φ20 mm, φ25 mm or φ30 mm indiameter, respectively, with the concave reflector of
51.9 mm in focal length.
The influence of the sound source size andreflector form is the same as the calculate result.
However the experimentally measured force islarger than the calculated one. This may be an errorof an experiment.
4. Conclusion
A sound field was generated under a flat orconcave reflector, and the sound field has beenstudied both by experimental measurement andnumerical calculation. A steel ball of 2.0 mm indiameter was levitated in air.

10
20
30
40
Distance from the sound source. [mm]50Fig. 2. Calculated force on steel ball along thesound beam axis.
20mm
80

25mm

60

3. Experiment

50

30mm

40
20
0
-20

(a) with a flat reflector.

-40
0

5
10
15
20
Distance from the sound source. [mm]80(b) with a concave reflector
60 (focal length 51.9mm).
40
20
0
-20
-40
0

5
10
15
20
Distance from the sound source. [mm]80(c) with a concave reflector
60 (focal length 77.8mm).
40
20
0
-20
-40
0

5
10
15
20
Distance from the sound source. [mm]Fig. 3. Measured force on steel ball along
the sound beam axis.
Acknowledgment
This work was supported by KAKENHI19560248.
References
1. T. Kozuka et. al.:Jpn. J. Appl. Phys. 47 (2008)4336.

3P8-13

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 477- 478
11-13 November, 2008

Aerial Ultrasonic Source Using Stripe-Mode Transverse
Vibrating Plate with Jutting Driving Point

凸端駆動による縞モードたわみ振動板型空中超音波音源
Hikaru MIURA , Hitoshi ISHIKAWA† (Coll. of Sci. & Tech., Nihon University)
三浦

光，石川

整†

(日大 理工）1. Introduction
As acoustic sources emitting strong acoustic waves in air,ultrasonic sources using a stripe-mode rectangular transverse
vibrating plate1 or a lattice-mode square transverse vibratingplate2 have been used. Because these sources are based on theresonance of transverse vibration, their electric-acoustic
conversion rate is as high as 90%, which is a merit. However, thedriving point of these acoustic sources is at the center of thevibrating plate, which interferes with the emission of acoustic
waves in air and restricts the utilization of the acoustic sources asdevices such as deodorizers. In this study, a vibrating plate with a
new shape was developed to enhance the effectiveness of
acoustic sources. Namely, the stripe-mode rectangular transverse
vibrating plate was improved such that the driving point wasoutside the plate. This is hereafter called a stripe-mode transverse
vibrating plate with a jutting driving point.
The following were experimentally examined. ①The lengthof the side parallel to the node line of the transverse vibratingplate at which the plate is preferably driven in the stripe mode.
②The driving conditions when the length between the driving
point and the edge of the vibrating plate is varied. ③The effect ofvarying the surface area of the vibrating plate by changing thelength of the side perpendicular to the node line of the vibratingplate.

2. Acoustic Source
Figure 1 shows the outline of an aerial ultrasonic source using
a stripe-mode transverse vibrating plate with a jutting driving
point. As shown in the figure, a 20kHz bolt-clamped
Langevin-type ultrasonic transducer is connected using screws toan exponential horn (diameter at the thick end, 70mm; diameterat the thin end, 10mm; amplification ratio, 7.0; made ofduralumin) used as an amplifier, to which a 1/2-wavelength
resonance rod (diameter, 10mm; made of duralumin) for
controlling the longitudinal vibration frequency is connected. The
tip of the rod is connected with the stripe-mode transverse
vibrating plate with the jutting driving point (plate thickness,
3mm; made of duralumin) using a screw.

3. Design of Vibrating Plate
Figure 2 shows an example of the stripe-mode transverse
vibrating plate with a jutting driving point. The dotted lines in the
figure represent the node lines of the vibrating plate. The lengthd between the nodes in the stripe mode is expressed asd=

πC D h(1)2f-----------------------------------------------------------miura@ele.cst.nihon-u.ac.jp, Real-giant@hotmail.co.jp

Driving point

Vibrating plate

1/2 Wavelength
resonance rod

Exponential horn
Bolt-clamped
Langevin-typeultrasonic transducer

Fig.1 Outline of an ultrasonic source.
L
LDVW
Driving pointdFig.2 Outline of vibrating plate (NL=12).
Here, CD is a material-specific constant, h is the plate thickness,and f is the frequency when the stripe mode appears at resonance.
By substituting CD=1.509kHz・mm, h=3mm, and f=19.8kHz,
which are obtained on the basis of the preliminary examination,
into eq.(1), d=18.86mm is obtained. The lengths of the sides
perpendicular and parallel to the node line of the vibrating plate, L
and W, respectively, are expressed as(2)
L = (N L − 0.5)d(3)
W = Nwd
Here, NL is the number of nodes and is a natural number, and NW
may have a noninteger value. Moreover, LDV in Fig. 2 is thelength between the driving point and the edge of the vibratingplate.
(4)
L DV = N i dHere, Ni may have a noninteger value.

4. Length of Side Parallel to Node Line ofVibrating Plate
In the case of a vibrating plate with the driving point at its
center, NW is an odd natural number1. In order to realize smooth
driving of the stripe-mode transverse vibrating plate with thejutting driving point, NW was experimentally examined. In theexperiment, when NL and LDV were fixed at 12 and 3.0,
respectively, and NW was changed in 0.1 steps between 4 and 6,
the electric impedance of the acoustic source was measured when
the stripe mode was observed at resonance. The result is shown in6. Examination of Vibrating Plate with Various
Surface Areas
In the case of a vibrating plate with a driving point at its center,
NL is an even number[1]. NL was also examined experimentally.
In the experiment, NW and LDV were fixed at 5.0 and 2.9,
respectively, on the basis of the above results, and NL waschanged in steps of 1 from 1 to 32 to examine. The stripe mode
was not observed at resonance at NL=15, 18, 21, 24, 27, and 30.
At other values of NL, the stripe mode was observed at resonance.

7. Quality Factor
For values of NL at which the stripe mode was observed atresonance, an admittance loop was observed by changing thefrequency. The quality factor was calculated for values of NL atwhich the stripe mode was observed at resonance. The result isshown in Fig.5. In the figure, the quality factor is small when NL
is 5 or less, even though the stripe mode is observed at resonance.
However, when NL is 6 or more, the quality factor, althoughslightly fluctuating, essentially remains constant at approximately
1,000. Therefore, it was found to be desirable to fabricate thestripe-mode transverse vibrating plate with the jutting driving
point by setting NL to be 6 or more.

8. Conclusions
In order to realize smooth driving of the stripe-mode transverse
vibrating plate with the jutting driving point, the numerical valueof NW and Ni of the vibrating plate was varied to experimentally
elucidate its optimal condition. As results, the following wereclarified: effective to set NW to be an odd natural number, similar
to the case of the stripe-mode square transverse vibrating plate,and effective to set LDV with a fractional part of 0.9. From theabove results, the area of the vibrating plate was experimentally
examined by varying the length of the side perpendicular to thenode line of the vibrating plate under the conditions of NW=5.0
and LDV=2.9. As a result, it was found that NL should be at least
6, but not a multiple of 3 greater than or equal to 15.
When a stripe-mode transverse vibrating plate with a jutting

Electric impedance [Ω]In order to realize smooth driving of the stripe-mode transverse
vibrating plate with the jutting driving point, LDW was also
experimentally examined. In the experiment, when NL and NW
were fixed at 12 and 5.0, respectively, which were determined on
the basis of the above result, and Ni was changed in 0.1 steps
between 1 and 3, the electric impedance of the acoustic source
was measured when the stripe mode was observed at resonance.
The result is shown in Fig.4. The figure reveals that Ni
fluctuates within a certain period and the impedance is large at
Ni=1.9 and 2.9. Therefore, it is effective to set LDV with afractional part of 0.9.

150

100

50

0

4

5

6

2

3

Numerical value of NW
Fig.3 Relationship between numerical value of NW
and electric impedance.
350
300

Electric impedance [Ω]5. Length between Driving Point and Edge ofVibrating Plate

200

250
200
150
100
50
0

1

Numerical value of Ni

Fig.4 Relationship between numerical value of Ni
and electric impedance.
1200
1000

Quality factor

Fig.3. The figure reveals that the impedance is large only at
NW=5.0 and is small at other values of NW. Therefore, it iseffective to set NW to be an odd natural number for the
stripe-mode transverse vibrating plate with the jutting driving
point, similar to the vibrating plate with the driving point at its
center.

800
600
400
200
0
0

5

10

15

20

25

30

35

Numerical value of NL

Fig.5 Relationship between numerical value of NL
and quality factor.
driving point is fabricated under the above conditions, it ispossible to smoothly drive the plate in the stripe mode atresonance.

References
1. H. Yamane and M. Kawamura: Nihon Onkyo Gakkai-Shi 32 (1976)
83 [in Japanese].
2. H. Miura: Nihon Onkyo Gakkai-Shi 50 (1994) 677 [in Japanese].

3P8-14

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 479- 480
11-13 November, 2008

Examination of Method for Judging Heat Receiving of Mortar
by Using Aerial Ultrasonic Waves Having Finite Amplitudes.
有限振幅の空中超音波を用いてモルタルの受熱を判定する
方法の検討
Youichi Ito, Naoto Asakura† (Sci. and Tech., Nihon Univ.)
伊藤洋一，朝倉直人† (日大・理工)

1. Introduction
We excited a mortar sample exposed to heat in a
non-contact way 1) by using high-intensity aerial
converging ultrasonic waves (20 kHz) with finite
amplitude, and determined the influence of the heatreceiving by analyzing the vibrations of the mortar sample.
This report discusses the relationship between irradiation
intensity of the sound waves and the vibration velocity fora mortar sample exposed to heat, with the converging
point of the ultrasonic waves coincident with the surfaceof the mortal sample. It also discusses the possibility ofdetermining the state of the mortar sample exposed to heatby analyzing the harmonic vibrations (40 to 100 kHz) of
the sample produced by irradiating the sound waves withfinite amplitude.

Emission direction
converter

Side f(front)Stripe-mode
vibration plateSound wave
converging point O o

SampleExponential hone

y

z

x

B.L.T.
Laser doppler vibrationgalvanometer with
optical-reflecting mirror

Fig. 1 Ultrasonic source andused for experiment.

device4

2. Sound Source and Experimental Method
Figure 1 shows the schematic view of the experimental
device. We used the point-converging acoustic source withstripe-mode vibration plate to generate high-intensity aerial
ultrasonic waves with finite amplitude.2) The ultrasonicwaves radiated by this sound source converged into a
circular section 10mm in diameter 140mm from theopening of the sound source, and provided intensive
ultrasonic waves of about 4000 Pa at the supplied powerof 50 W. In the experiment, the center on the surface of theSound pressure [Pa]

10

: 1st
(20kHz): 2nd(40kHz): 3rd(60kHz): 4th(80kHz): 5th(100kHz)

3

10

2

10

1

10

910

20

30 40 50 60

Electric power [W]

Fig. 2 Characteristics of ultrasonic waves atthe converging point.

mortar sample was made to coincide with the converging

TableⅠ Details of samples.

point O of the radiated sound waves, as shown in Fig. 1.
The sample was continuously irradiated with ultrasonicmortarwaves, and vibration displacements on the sample faceirradiated with the sound waves were measured using alaser Doppler displacement meter. TableⅠ gives thedetailed characteristics of the mortar samples used for theexperiment. We used a mortar sample (MS20) at the-----------------------------------------------------------yitoh@ele.cst.nihon-u.ac.jp

diameter[mm]
thickness[mm]
weight[g]volume[m３]
density[kg/m３]normal 500 ℃ 1000 ℃(MS20) (MS500)(MS1000)
49.96

50.46

50.50

21.42

19.84

19.52

91.08

76.88

71.48

3.966
4.197
3.908
×10−５ ×10−５ ×10−５
2170

1939

1829

3. Characteristics of Irradiated Sound Waves andVibration Velocity Characteristics of Mortar Samples
Figure 2 shows the relationship between the soundpressure and the power supplied to the sound source,
measured on the face (at point O) of the sample. Because
the sound waves with finite amplitude was used, thefundamental to fifth harmonic waves (20 kHz to 100 kHz)
were produced, as shown in the figure. Figures 3 and 4
show the vibration velocity characteristics of the samples
MS20 and MS1000 respectively. The figures indicate that
two samples vibrated at the frequencies corresponding to
the fundamental and harmonic sound waves respectively.
In comparison between the harmonic components of thetwo samples, it was found that the sample MS1000 had avibration velocity increasing at a higher rate than thesample MS20, as the sound pressure was higher.
4. Determination rate of Vibration and Influence ofHeat Receiving
Figure 5 shows the relationship between the vibration
velocity at the fundamental frequency and the harmoniccomponent rate (distortion rate) for each sample. The
figure indicates that each of the samples had a higher
distortion rate as a higher electric power was supplied, thatit had a higher distortion rate as the exposure to heat had agreater influence on the sample. If the same electric poweris supplied to the sound source, each of the samples had ahigher distortion rate as the exposure to heat had a greater
influence on the sample. It is obvious that samples had
different distortion rates.

Vibration velocity [m/s](MS1000) respectively for about 30 minutes.

: 1st
: 2nd
: 3rd
: 4th
: 5th

–2

10

–4

10

–6

10

0

2

10

4

10

10

Sound pressure [Pa]Fig. 3 Relationship between soundpressure and vibration velocity ofsample MS20 at the converging point.
Vibration velocity [m/s]to the atmosphere at 500 ºC (MS500) and 1000 ºC

: 1st
: 2nd
: 3rd
: 4th
: 5th

–2

10

–4

10

–6

10

10

0

2

4

10

10

Sound pressure [Pa]Fig. 4 Relationship between soundpressure and vibration velocity ofsample MS1000 at the converging point.
30

Distortion rate [%]normal temperature (20 ºC) as well as the samples exposed: normal(MS20): 500℃(MS500)20: 1000℃(MS1000)

10

0
0

20

40

60

Electric power [W]

5. Conclusions
When a mortar sample was excited in a non-contact way
by using high-intensity aerial point-converging ultrasonicwaves (20 kHz) with finite amplitude, the sample vibrated
at the frequencies corresponding to the fundamental andharmonic sound waves respectively. Moreover, it was
revealed that the sample’s ratio of vibration velocity at
harmonics to that at the fundamental frequency depended
on the influence that the exposure to heat had on thesample. It is also obvious that the sample had a ratio ofvibration velocity depending on the influence of theFig. 5 Relationship between Electric
power and Distortion rate.

exposure to heat. Therefore, it may be possible todetermine how much a mortar sample is exposed to heat.
References
1. Y. Ito, A. Oosumi and N. Asakura: Jpn. J. Appl. Phys. 47(2008) 4292.
2. Y. Ito: J. Acoust. Soc. Jpn. 46 (1990) 383-390.

3P8-15

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 481- 482
11-13 November, 2008

Linearly convergent Type Aerial Ultrasonic Source with
Changeable Incidence Angle of Sound Waves and Its
High-Intensity Sound Field.
音波の入射角度を変更できる線集束空中超音波音源とその音場
Youichi Ito† (Sci. and Tech., Nihon Univ.)
伊藤洋一† (日大・理工)

1. Introduction
It is considered that the method of utilizing theacoustical radiation force of high-intensity aerial
ultrasonic waves may be used to retain any small
solid object or liquid on the surface of an object
within the specific long and narrow region in the
non-contact way. 1) In this research, we used thelinearly convergent type aerial ultrasonic source 2)that had been developed. To use this method, it wasindispensable to form a standing-wave ultrasonicfield along the surface of an object. However, theexisting method of emitting sound waves from asound source could not form any standing-wave
sound field along the surface of an object. Thus, wedeveloped the method of changing the incident
angle of a converged sound waves relative to thesurface of an object by combining the conventional
linearly convergent type sound source with a newemission direction converter.
2. Principle and Characteristics of Sound Source
The conventional linearly convergent typeultrasound source comprises the combination of a
stripe-mode flexible vibration plate and a emission
direction converter A, as shown in Fig. 1, and canmake linearly convergent the sound waves radiatedfrom the both faces of the vibration plate so that thelength of the converged sound wave is almost equal
to that of the vibration plate. The converter A
comprises the same number of isolating plates asthat of nodal lines on the stripe-mode vibration
plate, and the parabolic reflecting plates inserted
between the isolating plates. A new convergent-typesound source is provided by combining thedirection converter B. Figure 2 shows the
cross-sectional views of the converters A and B
placed on the both faces of the vibration plate
respectively. The converter B has the same number-----------------------------------------------------------yitoh@ele.cst.nihon-u.ac.jp

Emission direction
converter B
z
y
x
O
・

B.L.T.
Horn

Stripe-mode
vibration plate
Emission direction
converter A
Reflecting plates b, c

Isolating plates

Fig. 1 Schematic sketch of new linearly
convergent ultrasonic source.

Vibratingplate

Converter A

Converter
B
O
Focal point

Reflecting
plate cz
Reflecting
plate bFig. 2 Arrangement of two converters andconverging of the ultrasonic waves.
of isolating plates as the converter A, and two typesof parabolic reflecting plate b and c are placed
between the isolating plates. The two parabolicreflecting plates have different focal lengths fromeach other, though they have their focal point at the
point O and their tops on the axis z. Therefore, thesound waves radiated from the vibration plate will

3. Conclusion
We proposed a new method of changing theincident angle of the converged sound waves
emitted by the linearly convergent type aerial
ultrasonic source, tentatively made the model of thesystem using this method, and experimentallydemonstrated the method. The results indicate that
it was possible to change the incident angle of theconverged sound waves emitted by the conventional
linearly convergent type sound source (19 kHz). We
also confirmed that it was possible to form thedesired standing-wave sound field.

Sound pressure [Pa](a)Converter A
Converter A+B

400

200

0 -20

Sound pressure [Pa](b)

0 20 40 60
Position, x [mm]Converter A

80

Converter A+B

400

200

0 –20

0
Position, z [mm]20(c)Sound pressure [Pa]be reflected by the reflecting plate a to go toward
the focal point 0, and then reflected by thereflecting plate b to propagate in the direction along
the axis z. Subsequently, the sound waves reflectedby the reflecting plate c will be incident into the
focal point 0 in the same phase, and converge.
Next, the basic characteristics of the linearly
convergent type sound source (frequency: 19.0kHz,
electric input power: 2W) will be described. The
solid lines as shown in Fig. 3 (a) to (c) indicate thesound waves converging characteristics of thesound source comprising only the converter A. The
dot lines as shown in Fig. 3 indicate the soundwaves converging characteristics of the soundsource comprising the converters A and B. The
figure indicates that the sound waves radiated fromthe vibration plate linearly converged. Here, theresults as shown in Fig. 3(b) are compared witheach other. The figure indicates that the wavelength
in the direction z is about 56mm for the solid line
and about 25mm for the dot line. Considering thesewavelengths as those in the direction z in the soundfield that is formed when two plane waves are
obliquely incident in the directions opposed to eachother, the incident angle relative to the axis z isabout 72º in solid line and about 44º in dot line.
This means that the incident angle of the soundwaves converging into the convergent point can bechanged by combining the converter A with theconverter B. The higher standing-wave ratio in thesound field, as shown by the dot line, indicates thata good standing-wave sound field is formed along
the surface of an object.

400

200
Converter A
Converter A+B

0 –1000100
Position, y [mm]Fig. 3 Distribution of sound pressure in thevicinity of the converging point. (a): in the
direction of the x-axis, (b): in the direction of
the z-axis, (c): in the direction of the y-axis.
References
1. Y. Ito, A. Oosumi and N. Asakura: Jpn. J. Appl.
Phys. 47 (2008) 4292.
2. Y. Ito: J. Acoust. Soc. Jpn. 42 (1986) 621-629.

3P8-16

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 483- 484
11-13 November, 2008

Applying diverging tube for the low temperature drive on theloop-tube type thermoacoustic system
ループ管型熱音響システムの低温度差駆動に向けた分岐管の利用
Takahiro Ishino1‡ , Shin-ichi Sakamoto 2 , Masahiro Nishikawa3 ,and Yoshiaki Watanabe4(1 , 3 , 4 Doshisha University ; 2 University of Shiga prefecture)
石野貴廣 1‡，坂本眞一 2，西川昌宏 3，渡辺好章 4（1 , 3 , 4 同志社大; 2 滋賀県立大）1. Introduction
Global warming, which results from greenhousegas emissions, has become a major task confronting
human society. In fact, large quantities ofgreenhouse gases generated to drive coolingsystems have been exhausted by wasteful systems.
To make efficient use of waste energy, we
specifically examine the loop-tube[1], which is athermoacoustic cooling system that can use wasteenergy effectively as a driving energy source. A
loop-tube
isanappliedthermoacoustic
phenomenon[2]: a loop-tube converts heat energy toand from sound energy.
2.

TheoryThe stack is the most important device in thissystem. The loop-tube is driven by forming an
extreme temperature difference at the tops andbottoms of a stack at the prime mover. Temperature
differences should exist at a low temperature to use
waste energy effectively at comparatively low
temperatures at factories and other installations. For
driving by low temperature differences, it isparticularly important to improve energy
conversion efficiency. Therefore, it is necessary toadjust the phase difference between the pressure
and particle velocity at a prime mover stack[3]. We
use the method of a loop-tube with a diverging tube.
A boundary condition by which the particle velocity
slows in the divergence path is added for the crosssection in the divergence part extension. According
to this boundary condition, the sound field is
controlled to generate the node of the particle
velocity, which is the antinode of pressure in thedivergence part. Consequently, the phase difference
between the pressure and the particle velocity at aprime mover stack is adjusted. This reportspecifically describes the effect that the installation
position of diverging tube exerts on the sound field.
3. Experimental system and method
A block diagram of the measurement system is
illustrated in Fig. 1. For the effect of diverging tube,
heat pump was not set. Tops of the stack were

defined to be 0 m. The tube center is the axis;
clockwise was defined as the positive direction. The
system was constructed with a stainless steel tube
of 1.01 m length, 0.5 m width, and 3.62 m total
length. Its inner diameter was 42 mm. The system
was filled with air at atmospheric pressure. The
stack was a 50-mm-long honeycomb ceramic with achannel radius of 0.47 mm. A spiral type electricalheater inserted at the upper part of a stack served as
the heat source; a heat exchanger to keep the room
temperature was placed at the lower part of a stack.
The inner diameter of the diverging tube was equal
to that of the loop-tube: 42 mm. The loop-tube’s
length from the upper side to the lower side was 0.4
m, as depicted in Fig. 1. Diverging-tube connecting
positions of four kinds were changed so that theposition from the heater to the upper part of thediverging tube side was 1.79 m, 1.89 m, 1.99 m, or
2.09 m.
Heating power of 330 W was supplied for 600 s
using a heater. Pressure sensors (PCB Inc.) were seton this system wall to measure the sound pressurein the loop-tube. Furthermore, the temperature of
the upper part of a stack was measured using
K-type thermocouples. Measurements of soundpressure and temperature started when heat energy
was supplied. They were carried out for 900 s.
The pressure, the phase difference between thepressure and particle velocity, and the amount ofsound intensity in this system were calculated using
the two-sensor power method with pressure
measurement results[4,5].
Pressure sensor
0.4 m
FFT
analyzer

1.79 mmove

0.15 mPC

2.09 mHeaterStackthermocouple
Heat
exchanger

PC
Digitalmultimeter

Fig. 1 Diagram of measurement system.

Results and discussion

5. Conclusions
This report described a design method of aloop-tube type thermoacoustic cooling system witha diverging tube for low temperature driving. By
adjusting the installation position of the diverging
tube, the conversion efficiency from heat energy tosound energy in the stack was improved by about
18 times. As a result, the device was driven by the
low temperature difference; the steady temperatureof the top of the prime mover stack was decreased
about 500°C. This method adjusted the phasedifference in the prime mover stack to perform heatexchange efficiently between the working gas andthe stack wall.
Acknowledgment
This research was partially supported by a
Ministry of Education, Culture, Sports, Science andTechnology Grant-in-Aid for Young Scientists (B),2007

without
1.79 m1.89 m6000

1.99 m
2.09 m2

Sound intensity [W/m ]

5000
4000
3000
2000
1000
0
0.0

0.5

1.0
1.5
2.0
2.5
Distance from the heater [m]

3.0

3.5

Fig. 2 Distribution of sound intensity in loop-tube.
900
without
1.79 m1.89 m1.99 m
2.09 m800
Temperature [degrees C]

Figure 2 shows the distribution of the soundintensity with and without a diverging tube in thesystem. Fig. 3 depicts the change of temperature at
the upper part of a stack. Fig. 2 shows that theamount of sound intensity with a diverging tube in
the system is higher than that of the non-diverging
tube. The sound intensity was highest when we set
up a diverging tube at the position of 1.99 m. At thisposition, the conversion efficiency from heat energy
to sound energy in the stack improved by about 18
times compared to that of the non-diverging tube. In
addition, the temperature of the top of a prime
mover stack was decreased about 500°C, from
845°C to 345°C, compared to that of thenon-diverging tube. It is considered that the energy
conversion improvement is major factor to induce
low temperature. The sound field in the loop tube
was adjusted by the diverging tube. Therefore, thephase difference in the stack approached an
appropriate phase difference at which the heatexchange occurred efficiently. Fig. 4 portrays the
distribution of sound pressure in the loop-tube withand without the diverging tube. That figure shows
clearly that the sound field was controlled so thatthe antinode of the sound pressure, the node ofparticle velocity, was excited in the divergence part.
The phase difference distribution was controlledsimilarly. The phase difference between thepressure and the particle velocity at the prime
mover stack was adjusted to improve the energy
conversion efficiency.

7000

700
600
500
400
300
200
100
0
0

100

200

300

400 500
Time [sec]

600

700

800

900

Fig. 3 Temperature variation of top of a stack.
5000
4000
Sound pressure [Pa]

4.

3000
2000
without
1.79 m1.89 m1.99 m
2.09 m

1000
0
0.0

0.5

1.0
1.5
2.0
2.5
Distance from the heater [m]

3.0

3.5

Fig. 4 Distribution of sound pressure in loop-tube.
References
1. S. Sakamoto et al. :Jpn. J. Appl. Phys. 45 (2006)
9257.
2. G. W. Swift : J. Acoust. Soc. Am. 84 (1998)
1145-1180.
3. P. H. Ceperley :Acoust. Soc. Am. 66 (1979)
1508.
4. A. M. Fusco, W. C. Ward, and G. W. Swift, J.
Acoust. Soc. Am. 91(4) (1992) 2229–2235.
5. T. Biwa, Y. Ueda, T. Yazaki, and U. Mizutani,
Cryogenics 41 (2001) 305–310.

3P8-17

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 485- 486
11-13 November, 2008

Effect of lamination mesh on energy conversion from sound toheat in thermoacoustic system
熱音響システムにおいて積層メッシュが音から熱へのエネル
ギー変換に及ぼす影響
Atsushi Sakaguchi1†, Shin-ichi Sakamoto2, Tsuji Yoshiyuki1 and Yoshiaki Watanabe1(1 Doshisha Univ., 2 Univ. of Shiga Pref.)坂口敦 1‡，坂本眞一 2，辻良行 1, 渡辺好章 1（1 同志社大，2 滋賀県立大）1. Introduction
A loop tube is a thermoacoustic coolingsystem. The loop tube consists of a prime moverand a heat pump. Heat energy is converted to soundenergy at the prime mover and sound energy isconverted to heat energy at the heat pump byapplication of the thermoacoustic effect[1–3]. A stackhaving very narrow channels is in the prime moverand the heat pump. We have studied energy
conversion in the stack of the heat pump using an
acoustic tube with a connected compression driver,for example, a loudspeaker, etc. A previous work[4]suggested that the best insertion position of thestack is uniquely determined when the driving
frequency and channel radius of the stack are varied
under identical ωτ[4, 5], which is the parameter
controlling energy conversion. Furthermore, thebest insertion positions approach the acoustic tube’s
center by decreasing the value of ωτ. These results
demonstrate that the value of ωτ can be a usefulindex of the insertion position of the ceramic stack.
For practical application of the loop tube, it isimportant to improve its energy conversion
efficiency. Increasing the number of stack channels
is effective to increase the thermal boundary layer
in which energy conversion between the oscillating
gas and the stack wall occurs. In addition, reducing
the channel radii of the stack increases the numberof channels. Consequently, reducing the channel
radii of the stack is equivalent to increasing thethermal boundary layer. It is difficult for a ceramic
stack to reduce the channel radii of the stackbecause of presently used manufacturing techniques.
Therefore, we use a lamination mesh which isformed by piling up stainless mesh pieces to reducethe channel radii of the stack; however, the coolingproperty of the lamination mesh remains unclear
and the value of ωτ using the lamination meshcannot be calculated. This study investigatescooling characteristics of the lamination mesh andexamines the value of ωτ and the channel radius of
the lamination mesh.

2. Theory
The parameter ωτ is expressed by thefollowing equation [5].

ωτ = ω

r2
2α(1)

In that equation, r denotes the channel radius of thestack and α is the thermal diffusivity, and ω is theangular frequency of the sound wave. Whentemperature of the working gas is constant,ωτ depends on only the resonant frequency and thechannel radius of the stack.
3. Experimental setup
A block diagram of the measurement system
is shown in Fig. 1. The loudspeaker was put into
one side of the acoustic tube; the other side is a
closed end. The driving frequency is set as 100 Hz
to generate a one-wavelength mode. In thisexperiment, meshes of three types were used, themesh numbers of the lamination meshes––thenumber of meshes per inch––were 10, 20, and 40.
The lamination mesh thickness is 15.0 mm; thelaminating pattern is random. The loudspeaker sideof the acoustic tube is defined as forward. The
closed end side is defined as backward. Backwardof the lamination mesh is defined as the insertion
position of the lamination mesh and a measurement
point of the temperature change. The insertion
position of the lamination mesh was moved from1.60 to 1.85 m. The temperature change wasmeasured using a K-type thermocouple.
4. Results
Figure 2 presents temperature measurement
results. This figure shows that every temperature
Forward3.3 m

backward

Lamination mesh
42.0
mm
Loudspeaker

Insertion
position

Closed end
K-type thermo couple
Digital multimeter

PC

Fig. 1 Block diagram of measurement system.

6. Conclusion
Experiments were carried out by changing
the mesh number and the insertion position of thelamination mesh using the acoustic tube to measure
the cooling characteristics of the lamination mesh.
The experimental results reveal a tendency similar
to that of a ceramic stack. Values of ωτ and thechannel radius of the lamination mesh were
estimated in the previous work. Results presented
herein suggest that the same design method can beadapted to use of the lamination mesh and aceramic stack.
Acknowledgment
This research was partially supported by a Ministryof Education, Culture, Sports, Science andTechnology Grant-in-Aid for Young Scientists (B),2007

Temperature decrease [℃]

2.5
2.0
1.5
1.0
10mesh10mesh20mesh20mesh40mesh40mesh

0.5
0.0
1.60

1.65

1.70

1.75

1.80

Distance from loudspeaker [m]Fig. 2 Temperature decrease as a function of thestack distance from the loudspeaker.
1.66 m 1.70 m

Temperature decrease [℃]

5. Discussion
Peak positions were normalized by the lengthof the acoustic tube to simplify these results. As itturns out, normalized peak positions of 10, 20, and40 mesh were 0.527, 0.515, and 0.503. Therefore,
the normalized peak positions come closer to centerof the acoustic tube because of the increased mesh
number. An increasing mesh number is similar in its
effect to a reduction of channel radii. Furthermore,from eq. (1), reducing the channel radii isequivalent to decreasing the value of ωτ.
Consequently, the normalized peak positions comecloser to the center of the acoustic tube because of
the decrease in ωτ. In the previous work[4], thenormalized peak positions of the ceramic stackcome closer to the center of the acoustic tube bydecreasing the value of ωτ. The experimental
results reveal a tendency resembling that shown by
a ceramic stack.
In addition, values of ωτ using the lamination
mesh were estimated from the previous work andexperimental results. Figure 4 shows results ofprevious work related to the normalized peak
position under each value of ωτ using a ceramic
stack and relevant experimental results. Results
show that ωτ of 10, 20, and 40 mesh wereapproximately 1.3, 1.0, and smaller than 1.0.
Moreover, channel radii of the lamination meshwere calculated from these values of ωτ. Channel
radii of the lamination mesh using 10, 20, and 40
mesh were approximately 0.3, 0.2, and smaller than
0.2 mm. These results suggest that the same design
method is adaptable to the use of a lamination meshand a ceramic stack.

1.74 m

2.5
2.0
1.5
1.0
10mesh20mesh40mesh

0.5
0.0
1.60

1.65

1.70

1.75

1.80

Distance from loudspeaker [m]Fig. 3 Temperature decrease as a function of thestack distance from the loudspeaker(three-dimensional approximated curve).
ωτ = 0.7

Temperature decrease [℃]measurement is a temperature decrease. A
three-dimensional
approximate
curve
was
calculated, as shown in Fig. 3, to estimate eachpeak position of the temperature decrease. Fromthese results, the peak positions of each lamination
mesh were observed. The peak positions of 10, 20,
and 40 mesh were 1.74, 1.70, and 1.66 m.

ωτ = 1.3ωτ = 1.7

2.5
2.0
1.5
1.0
10mesh20mesh40mesh

0.5
0.0
0.48

0.50

0.52

0.54

Normalized position
Fig. 4 Comparison of stack position with ωτ.

References
1. P. H. Ceperley, J. Acoust: Soc. Am. 77 1239-1244(1985)
2. S. Backhaus, G. W. Swift: Nature 339, 335-338(1999)
3. S. Sakamoto, Y. Watanabe: Acoust. Sci. & Tech.,27(6), 361-365(2006)
4. Y. Tsuji, S. Sakamoto, T. Ishino, Y. Watanabe, J.
Senda: Jpn. J. Appl. Phys. 47, 4231-4264(2008)
5. A. Tominaga: Netsuonkyo-kougaku-no-kiso(FundamentalsofThermoacoustics),(Utidaroukakuho, Tokyo, 1998) pp. 117 [inJapanese].

3P8-18

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 487- 488
11-13 November, 2008

The Effect of Membrane Insert Position on the Acoustic Field
in a Thermoacoustic System
熱音響システムにおいて薄膜の設置位置が管内音場に与える影響
Masahiro Nishikawa1†, Shin-ichi Sakamoto2, Takahiro Ishino3 and Yoshiaki Watanabe4(1,3 Facult. Eng., Doshisha Univ.; 2 Facult. Eng., The Univ. of Shiga prefecture;and 4 Facult. Life and Med. Sci., Doshisha Univ.)
西川昌宏 1‡，坂本眞一 2，石野 貴廣 3，渡辺好章 4（1,3 同志社大 工; 2 滋賀県立大 工; 4 同志社大 生命医科）

1. Introduction
Although progress in science and technology
has brought us many amenities, it has depleted naturalenergy resources. From the standpoint of grobal
emvironment conservation, the issue of fossil fueldepletion is especially important, but switching toalternative fuels has social, economic, andtechnological problems. Therefore we focus onefficent use of energy, and study the practicalapplication of the thermoacoustic cooling system
which can utilize waste heat. The system uses thethermoacoustic phenomenon[1] which enables
interconversion between heat and sound energy.
In this report, we conducted an experiment withmembrane varying its position for the purpose ofadjusting the acoustic field in the loop-tube typethermoacoustic system and discussed its effect.
2. Theory
Figure 1 shows the schematic view of theloop-tube and a photograph of a stack. The
thermoacoustic phenomenon realize heat energy
transport by heat exchange between medium and thechannel walls in the stack, and simultaneous medium
oscillation. Phase difference between sound pressure
and particle velocity affects energy transport in thestack. It is known that energy conversion efficiency
from heat to sound reaches its maximum when thephase difference nearly equals to 0 degree[2,3] at theprime mover. Therefore the phase difference becomes
important when the phenomenon is used.
In the loop-tube, the prime mover produces themedium’s self-oscillation. The wave length of thesound equals to the total length of the loop-tube. Nodeof particle velocity and antinode of sound pressure
distribution are observed near the prime mover.

When a membrane is inserted to the loop-tube,
it adds a new boundary condition which makes
particle displacement smaller to the insert position.
Particle velocity is in proportion to particle
displacement; therefore membrane insertion shifts theacoustic field along the tube axis, and the distributionof phase difference.
3. Experiment
Figure 2 shows the experimental system. We
compared acoustic fields varying in insert position of
membrane above the prime mover to the acoustic field
without membrane. The heat pump was eliminatedfrom the experimental system to simplify theobservation. Measuring points were defined clockwisewith the axis centered in the tube and a HHEX set at 0mm. The membrane was made of L-LDPE and its
thickness was 0.06 mm. The system was constructedwith stainless tube of 2800 mm in total length and theinner diameter was 42 mm. The thickness of the stack
was 50 mm and the radius of stack channels was 0.47
mm. Air was filled in the system at the atmospherepressure. The HHEX was a spiral type electric heaterat the top side of the stack. The room temperature
HEX was made of copper and the temperature was
kept consistent by circulating water. Heat input energy
from HHEX was 330 W.
The measuring time was 1000 seconds, with theheat supplied for the first 600 seconds only. 8 pressure
sensors were set on the inner wall of the tube toobserve acoustic field in the system, and obtained data
was used to determine distribution of sound pressure,particle velocity, phase difference between them, andsound intensity by two-sensor power method[4].
FFTanalyzer

Heat pump
Circulating
water

HeaterStack
Prime mover

Stack
Cooling point

Circulatingwater

Fig.1 Schematic view of the loop-tube anda photograph of a stack.

Membrane

450 mmACsource

150 mmThermocouple

HeaterCirculating
water

0 mm
Stack

PC
Pressure
SensorPC
DigitalmultimeterFig.2 Block diagram of the experimental system.

5. Conclusions
Our experiment was aimed at adjustment of
acoustic field, especially phase difference between
sound pressure and particle velocity in a loop-tube
type thermoacoustic cooling system.
We focused on the change in distribution ofphase difference when insert position of the membrane
was varied at certain input heat energy.
It was found that the sound intensity increased
as the insert position of the membrane became closer
to the stack. This was due to higher energy conversion
efficiency from heat to sound. It is considered that the
improvement of the efficiency was achieved by the
adjustment of phase difference between soundpressure and particle velocity at prime mover, anddecrease in viscous resistance in the stack channels.
Acknowledgment
This research was partially supported by a
Ministry of Education, Culture, Sports, Science andTechnology Grant-in-Aid for Young Scientists (B), 2007.

2000

without membrane

1500

with membrane
at 150 mm
at 250 mm
at 350 mm
at 450 mm

2Sound intensity [W/m ]Membrane

1000
500
0
0

500

1000
1500
2000
2500
Prime mover
Position [mm]Fig.3 Distribution of sound intensity;
at 400 sec. after heat supply started.
Phase difference [degree]

90
60
30
0

without membranewith membrane
at 150 mm
at 250 mm
at 350 mm
at 450 mm

-30
-60
-90
0

500

1000
1500
2000
Position [mm]2500

Fig.4 Distribution of phase difference between soundpressure and particle velocity;
at 400 sec. after heat supply started.

Particle velocity [m/s]

4. Results and Discussion
Figure 3 shows the distribution of soundintensity at 400 seconds after heat supply started.
Dashed thick line in Fig.3 indicates each position of
the membrane. The most remarkable point in thisfigure is that the sound intensity increased as themembrane was moved closer to the prime mover inthis measurement range. The three possible reasonsare as follows:
The first reason is the adjustment of phasedifference between sound pressure and particle
velocity at the position of the prime mover by shifting
distribution of phase difference. The distribution ofphase difference shown in Fig.4 indicates that thephase difference at the prime mover came close to asuitable value as described in Chapter 2 “Theory.”
The second reason is decrease in viscous
resistance in the channels of the stack caused by theshift of distribution of particle velocity. Fig.5 shows
the distribution of particle velocity at 400 seconds
after heat supply started. This figure indicates that as
the membrane was moved closer to the prime mover,the node of particle velocity distribution came to theprime mover. As a result, particle velocity in the stack
channels decreased to reduce viscous resistance.
The last reason is decrease in viscous resistancein the stack channels caused by thinning of viscousboundary layer. Due to the aforementioned two
reasons, the energy conversion efficiency from heat tosound was improved to thin the viscous boundary
layer. As a result, temperature of top side of the stack
decreased, and the viscous resistance decreased.
As an addional insight in Fig.3, there wereincreases in sound intensity distribution when themembrane was at 150 and 200 mm. It suggests that
membrane insertion caused suppression of mass
flow[2,5] in this system to improve the energy
conversion efficiency from heat to sound.

10
86
without membrane4with membrane
at 150 mm
at 250 mm
at 350 mm
at 450 mm

2
0
0

500

1000
1500
2000
Position [mm]2500

Fig.5 Distribution of particle velocity;
at 400 sec. after heat supply started.
References
1. A. Tominaga: (Uchida roukakuho, Tokyo, 1998.)[inJapanese]
2. Y.Imamura, S.Sakamoto and Y.Watanabe,
Jpn. J. Appl. Phys., 46(7A), 4417-4420, 2007.
3. P. H. Ceperley, Acoust. Soc. Am. 66 (1979) 1508.
4. Andrew M.Fusco, William C. Ward, and Gregory W.
Swift, J. Acoust. Soc. Am. 91(4), (1992)
5. S.Sakamoto, T.Tsujimoto and Y.Watanabe,
Jpn. J Appl. Phys. 38, (1999).
(dth0155†1,dth01183)@mail4.doshisha.ac.jp,(ssakamot2,kwatanab4)@mail.doshisha.ac.jp

3P8-19

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 489- 490
11-13 November, 2008

Rotation Phase Analysis of Surface Particle Motion of
Coiled Waveguide for Flexural Ultrasound Wave
屈曲超音波伝搬路における表面粒子運動の回転位相解析
Ryo Tanaka†, Masayuki Tanabe, Kohei Tomoda, Kan Okubo and Norio Tagawa(Faculty of System Design, Tokyo Metropolitan Univ.)
田中亮‡，田邉将之，友田耕平，大久保寛，田川憲男（首都大システムデザイン）

1. Introduction
We have developed a traveling wave-typeminiature ultrasonic motor using a helical coiled
waveguide as a stator, which is called CS-USM(Coiled Stator Ultrasonic Motor)1), and have alreadyapplied it to an IVUS (Intravascular Ultrasound)probe.2-4) In this motor, the elliptical motion of thesurface particle due to the flexural ultrasonic waves
rotates the rotor, which can be placed adjacently
inside or outside the stator, via the frictional force.
For high frequencies, rotational directions of bothof the inner rotor and the outer rotor are consistent
with those of usual traveling wave-type ultrasonicmotor. However, for low frequencies, the outerrotor rotates inversely. In the previous studies, we
examined the rotational direction of the surface
particle motion of a coiled waveguide for low
frequencies, and we clarified that the direction at
the inner surface and the direction at the outersurface are the same, which is not realized by astraight-line waveguide.5,6) In this study, we
examine the rotation phase at the both surfaces
through simulations.
2. Methods
In this study, using the PZFlex, which is astandard FEM simulator for ultrasound propagation,and modeling a helical coiled waveguide with astainless steel wire, we simulate the surface particle
motion due to traveling flexural waves at both of
the inner and the outer surfaces for low frequencies.
In the simulations, the density of the stainlesssteel wire is set as 7910 kgm-3, the sound speed oflongitudinal wave is 5790 m/s, and the sound speedof transverse wave is 3100 m/s. The width and thethickness of it are set respectively as 0.3 mm and
0.1 mm, and the inner diameter of the helical coiled
structure is 0.3 mm.
3. Results
Figure 1 shows the direction of the surface
particle’s motion qualitatively. Figure 2 shows the-----------------------------------------------------------Email: tanaka.ryo.9.11@gmail.com

actual loci of the surface particle obtained throughsimulations for the low frequency of 0.3 MHz. In
this figure, “r-dir” indicates the radial direction of
the coil, and “θ-dir” indicates the direction of wave
propagation. The loci are decomposed into the r-dir
component and the θ-dir component, and these are
analyzed as a time series in Fig. 4 to examine therotation phase. In Fig. 2, “t = 46.62 μs” and “t =53.21 μs” indicate respectively the start and end
time of the time series shown in Fig. 4, and thelocus drawn by solid and thick line corresponds tothe such time series. Similarly, Fig. 3 shows theresults of the motion for the high frequency of 3MHz. From Figs. 2 and 3, we can confirm that therotation direction of the outer surface for low
frequencies is reverse to that for high frequency.
As mentioned above, Fig. 4 shows time series
representation of the surface particle motion for 0.3
MHz, and Fig. 5 shows that for 3 MHz. In the both
figures, “Dr” indicates the r-dir component and“Dθ” indicates the θ-dir component. Fig. 5 indicates
that, for high frequencies, the particle motion
properties at both surfaces are completely equal tothat caused by the anti-symmetric mode of theLamb wave, i.e., there are no difference between
the coiled structure and the straight-line structure.
On the other hand, the coiled structure influences
the property for low frequencies. From Fig. 4, it canbe confirmed that the rotation phases at the both
surfaces are almost the same in addition to therotational direction.

4. Discussions and Conclusions
In a coiled waveguide for low frequencies,
the motion phase along the surface normal direction
coincides with that of the anti-symmetric mode in astraight-line waveguide, but the rotation direction at
the outer surface equals to that of the symmetricmode. These properties indicate that thecomplicated wave mode exists. It is desirable toinvestigate the detail and the microscopic
mechanism of this mode.

Propagation direction

(a)

(b)

0.4

t =46.62μs
0.2
0
-0.2

(a)
-0.4

-0.2

0

0.2

0.4

Phase (rad)Displacement (μm)

t =46.62μs
0.2
0
-0.2
-0.4

(b)
-0.4

-0.2

0

0.2

0.4

0.6

Displacement along θ-direction (μm)

Displacement along θ-direction (μm)

-0.2

0.06

(a)

0.04
0.02
0
-0.02

t =13.09μs
-0.04

-0.02

t =12.43μs
0

0.02

0.04

Displacement along θ-direction (μm)

0.06

Displacement along r-direction (μm)

0.06

Displacement along r-direction (μm)

47

48

49
50
Time (μs)

51

52

53

51

52

53

π
Dr

0

Dθ

-π
0.6
Dr

0.4
0.2

Dθ

0
-0.2

47

48

49
50
Time (μs)

π

(b)

0.04
0.02
0
-0.02
-0.04
-0.06
-0.06

Dθ

0

Dr

-π
0.05
Dr

0

Dθ

t =12.43μs
-0.04

-0.02

t =13.09μs
0

0.02

0.04

0.06

Displacement along θ-direction (μm)

Fig. 3 Analytical result of surface particle motion forhigh frequencies at (a) outer surface and (b) innersurface.

12.5

12.6

12.7
12.8
Time (μs)

12.9

13

π
Dr

0

Dθ

-π
0.05
Dr

0
Dθ

-0.05

(b)

-0.06
-0.06

Dθ

0

(a)

0.4

-0.6
-0.6

0.6

Phase (rad)t =53.21μs

Fig. 2 Analytical result of surface particle motion for low
frequencies at (a) outer surface and (b) inner surface.

-0.04

Dr

0.2

-0.05

0.6

t =53.21μs

Phase (rad)0.6

Displacement along r-direction (μm)

Displacement along r-direction (μm)

Fig. 1 Outline of surface particle’s rotation with a helicalcoiled waveguide. (a) Low frequencies. (b) Highfrequencies.

Displacement (μm)

y

y

-0.6
-0.6

0.4

Vibration

Vibration

-0.4

Dθ

-π
0.6

Fig. 4 Time series representation of surface particle
motion for low frequencies by decomposing locus in Fig.
2 into two components. (a) indicates outer surface and(b) indicates inner surface.

x
Propagation direction

Dr

0

(b)

Displacement (μm)

x

π

(a)
Phase (rad)References
1. T. Moriya, Y. Akano and Y. Furukawa: IEEE
Ultrasonics Symp. (2005) 1546.
2. S. Xie, M. Tanabe, N. Tagawa, T. Moriya and Y.
Furukawa: IEEE Ultrasonics Symp. (2006) 1301.
3. M. Tanabe, S. Xie, N. Tagawa, T. Moriya and Y.
Furukawa: Jpn. J. Appl. Phys. 46 (2007) 4805.
4. M. Tanabe, S. Xie, N. Tagawa, T. Moriya: Jpn. J.
Appl. Phys. 47 (2008) 4262.
5. S. Xie, M. Tanabe, N. Tagawa and T. Moriya:
IEEE Ultrasonics Symp. (2007) 2284.
6. S. Xie, M. Tanabe, K. Okubo, N. Tagawa and T.
Moriya: Jpn. J. Appl. Phys. 47 (2008) 4271.

Displacement (μm)

Acknowledgment
This work was supported by the research funds
from KONICA MINOLTA MEDICAL &GRAPHIC, INC.

12.5

12.6

12.7
12.8
Time (μs)

12.9

13

Fig. 5 Time series representation of surface particle
motion for high frequencies by decomposing locus in Fig.
3 into two components. (a) indicates outer surface and(b) indicates inner surface.

3P8-20

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 491- 492
11-13 November, 2008

Development of precise rotation manipulator of a ballbased on resonant vibration of cantilever
カンチレバーの共振を利用した
球体の精密回転マニピュレータの開発
Teruyuki Tomita1, 2‡, Toshihiro Tsuji1, 2 and Kazushi Yamanaka1, 2(1 Tohoku Univ., 2 JST,CREST)
冨田輝之 1, 2‡, 辻俊宏 1, 2, 山中一司 1, 2 (1 東北大, 2 JST,CREST)

1. Introduction
Precise rotation manipulator of a ball is requiredfor observation of surface structures or formachining. Rotation control with 3-axes has alreadybeen achieved using multiple vibration modes of acylinder [1]. In this work, we propose an alternative
geometry, a cantilever manipulator, suitable for
installation into narrow gaps or for integrated mass
production by micro electromechanical systems(MEMS) technology. The cantilever has resonant
vibrations such as deflection (D), lateral bending(LB), and torsion mode [2-5]. In principle, it is also
suitable for batch deposition of thick piezoelectricfilms [6,7]. In this study, we develop a ballmanipulator driven with cantilevers, and applied it
to observation of a ball SAW device used for highsensitivity gas sensor and chromatographs [8,9].
2. Principle
The principle of the manipulation is shown in
Fig.1. The D mode rotates the ball around the
Y-axis in the direction of counter clock wise, since
the ball is lifted due to the inertia during tapping by
the cantilever, such as in the ultrasonic force
microscopy [2]. The LB mode rotates it around the
Z-axis. The rotation direction is dependent on the
direction of differential friction force of a point
contact. Moreover, various rotation axes will be
realized using two or more cantilevers bycontrolling the amplitude and phase of excitation
signal of each cantilever, independently.
3. Experimental setup
We fabricated three cantilevers manipulator(Fig.2 (a)), with a width of 2mm and a length of
25mm ([100] direction), cut from a 0.5 mm thick Si
wafer. The end of the cantilever was glued to a
4mm-square, 1mm thick PZT vibrator and it was
glued to a thick Cu substrate. Fig.2 (b) shows the
manipulator supporting a LGS ball SAW device
with a diameter of 3.3mm.
a7tm5621@stu.material.tohoku.ac.jp

Ball sample

(a)
Y

Z
Deflection
vibration

Y
X

Support(b)

Lateral bending
vibration

Z

X
Z
Y

Fig. 1 Principle of rotation of a ball using cantilever.
(a) Deflection mode. (b) Lateral bending mode.
Si cantilever (25mm x 2mm x 0.5 mm)
Cantilever used to rotate a ball
(b)

(a)

Bx

xA

1mm

PZT
IDT

Z

Y

X

Si cantileverCu substrate (GND) Ball SAW device(φ3.3mm)

Fig. 2 Manipulator with three cantilevers. (a)Schematic illustration. (b) Ball SAW device on the
manipulator.

4. Vibration spectra of the cantilever
We measured vibration spectra of the cantileverat positions A and B shown in Fig.2 (b) withexcitation amplitude of 2.24V. In Fig.3 (a) dashedand solid curves represent noncontact spectrum andcontact spectrum to a ball SAW device at position A,
respectively. The 3rd D (D3) mode was identified
from the theoretical analysis of free resonancefrequency, assuming Young’s modulus, Poisson’sratio, and density of Si to be 166GPa, 0.22, and2.33x103kg/m3, respectively. When the ballcontacted the cantilever, the resonance frequency
increased from 22.20kHz to 24.13kHz and Q factor
decreased
from
42.0
to
19.0.
The
low-frequency-shift is explained by a tapping
contact of the cantilever [3]. Fig.3 (b) shows the
spectra measured at position B. The 2nd LB (LB2)mode [4,5] was identified from similar analysis.
When the ball contacted the cantilever, resonancefrequency increased from 28.73kHz to 29.81kHz
and Q factor decreased from 80.7 to 21.6. Thesechanges may be useful for monitoring of contact
and surface/subsurface state of the balls [5].

Velocity (mm/s)

2

Noncontact
Contact on ballY-axis, centering the IDT in the view of microscope.
Thus, the desired manipulation was achieved.
1mm

(a)

(b)

Z
Y
X

(c)

(d)

(e)

(f)

Noncontact
16

8

Contact on ball(+10dB)

1
4

0.5

22

24

26

Frequency (kHz)

2
28

30

32

34

Frequency (kHz)Fig. 3 Vibration spectra of free end of a cantilever.
(a) Deflection vibration. (b)Lateral bending vibration.

5. Manipulation of a ball SAW device
We observed the rotation of a ball. When wedrove the manipulator at the D3 mode, the ball was
rotated around the Y-axis at 23.70kHz and 100V.
The rotation direction was consistent with theprinciple shown in Fig.1 (a). When we drove themanipulator at the LB2 mode, the ball was rotatedaround the Z-axis at 29.70kHz and 100V. The
rotation direction was clockwise.
Next, we tried to decrease the rotation speed, by
driving intermittently using burst wave signal withduration nb cycles and interval ni cycles shown in
Fig.4. We rotated a ball SAW device for microscopeobservation of the IDT and surface condition of
crystal ball around it (Fig.5).
Burst duration(nb cycles)

Interval(ni cycles)

Duty ratio: nb/(nb+ni)

Fig. 4 Schematic illustration of burst wave excitation
signal.

Figs.5 (a-c) show the manipulation using the LB2
mode. Duty ratio of the burst was 9.1% and the ball
was rotated around the Z-axis. Figs.5 (d-e) show the
manipulation using the D3 mode. Duty ratio of the
burst was 33.3% and the ball was rotated around theFig. 5 Rotation of a ball SAW device. (a) At start. (b)After LB2 mode for 2.2s from (a). (c) After LB2 modefor 4.4s from (a). (d) After D3 mode for 3s from (c).
(e) After D3 mode for 6s from (c). (f) After D3 modefor 9s from (c).

6. Conclusion
We proposed a cantilever manipulator and rotateda ball SAW device both around the Y and the
Z-axes using deflection and lateral bending
vibration, respectively. This manipulator may bemass-produced by and applied to MEMS processes.
References
1. Y. Gouda, K. Nakamura, and S. Ueha: Ultrasonics 44(2006) e617.
2. K.Yamanaka, H. Ogiso, O. Kolosov: Appl. Phys. Lett.
64 (1994) 178.
3. K. Yamanaka, A. Noguchi, T. Tsuji, T. Koike, and T.
Goto: Surf. Interface Anal. 27 (1999) 600.
4. T. Tsuji, K. Kobari, S. Ide, and K. Yamanaka: Proc.
Symp. Ultrason. Electron. 27 (2006) 185.
5. K. Yamanaka, K. Kobari and T. Tsuji: Jpn. J. Appl.
Phys. 47 (2008) 6070.
6. J. Akedo, and M. Lebedev: Appl. Phys. Lett. 77 (2000)
1710.
7. M. Nakazawa, M. Tabaru, K. Nakamura, S. Ueha, and
A. Maezawa: Jpn. J. Appl. Phys. 46 (2007) 4466.
8. K. Yamanaka, S. Ishikawa, N. Nakaso, N. Takeda, D.
Y. Sim, T. Mihara, A. Mizukami, I. Satoh, S. Akao, and Y.
Tsukahara: IEEE Trans. Ultrason. Ferroelectr. Freq.
Control 53 (2006) 793.
9. N. Iwata, T. Abe, T. Tsuji, T. Mihara, S. Akao, and K.
Yamanaka: Jpn. J. Appl. Phys: 46 (2007) 4532.

3P8-21

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 493- 494
11-13 November, 2008

Loudspeaker by Ultrasonic motors and it’s control system
超音波モータを用いたスピーカの制御方法
YusukeMasuda 1†, KeigoHigashida 1, Syunsuke Chiba 1, Hirokazu Negishi 2, Juro Ohga 3,
Kazuaki Maeda 4 and Hajime Kubota 1 (1 Chiba Institute of Tech; 2 MIX Acous Lab; 3
MIX Acous Lab/Shibaura IT; 4 TOA.)
増田裕輔 1‡，東田啓吾 1，千葉俊輔 1，根岸廣和 2，大賀寿郎 3，前田和昭 4，久保田一 1(1 千葉工大 工; 2MIX 音研; 3MIX 音研/芝浦工大; 4TOA）

1.

Introduction

Piezoelectric ultrasonic motor is known for
their use in precise positioning apparatus in IC
manufacturing plants.
It is our proposal to utilize this motor as adriver of a loudspeaker for low frequency
reproduction, exploiting its high mechanical
impedance. Introduction of ultrasonic motor
seems to overcome common shortcomings ofordinary electrodynamic loudspeakers1.
This report covers results of our recent
measurements and evaluation of our mostrecent prototype.
2. The principle of Ultrasonic motor and its
driving method Principle

USR60E3 by Shinsei Kogyo is used in our
prototype2. Fig.1 shows the cut out photo
which shows the location of piezoelectric
actuator, teethed stator and metallic rotor.
Principle of ultrasonic motor is familiar to theparticipants of this symposium therefore only
basic reminder is shown is Fig.2
Two asynchronous 40-45 kHz sine waves ofthe same frequency are needed in order for a
USR60 to generate progressive wave.
2.1Driving method
The revolution velocity of the motor is varied
by changing the amplitude of the progressive
wave on stator surface. In order to do this,amplitude, frequency, or phase difference of thetwo sine waves can be modulated. Relationshipbetween loudspeaker output and amplitude
modulation input was found to be non-linear,
but those for frequency and phase difference
are not yet studied. In order to reverse thedirection of rotation, the phase difference
between the two input signals simply has to bereversed.
-----------------------------------------------------------Masuda_1983@hotmail.com

Fig 1 Ultrasonic motor USR60E3
Suppress strength Suppress strength
Movement
運動

進行波
Progressive
Wave

sinωt

cosωt

Rotor

Stator

INPUT SIGNAL

Fig 2 Driving principle
2.2Frequency Modulation
Fig. 3 explains the relationship between input
frequency and revolution speed. The motor
exhibits linearity in the area of 41-42+ kHz but
gradually levels off after 42+ kHz. The
loudspeaker utilizes this linear region for its
operation. Minor deviation is observed in
No.10475 which hit top speed around 39.5 kHz.
This was the only brand-new motor which
could account for the reason for this difference.
2.3Phase difference modulation
Phase difference vs. rotational speed is shownin Fig. 4. It is apparent that except for -5 to +5

Revolution per minuite [rpm]degree region, linearity in change is observedin between -30 to +30 degrees. In case ofdriving reciprocal type loudspeaker, -5 to +5
degree area should be skipped from themodulation.
300
250
No.10034
No.10036
No.10038
No.10162
No.10475

200
150
100
50
0
39.0

41.0

43.0
45.0
Frequency [kHz]47.0

Fig5 Dual motor modelFig 3 Input signal frequency vs. RPM

Revolutions per minute(rpm)

150
100
50

No.100340No.10036

Measured distance :1m
Measured Place :anechoic room (CIT)

Dual-motor model
Ordinary electrodynamic

No.10038-50

No.10162-100

No.10475

-150
-90

-60

-30

0

30

60

90

Phase[deg]Fig 4 Input signal phase difference vs. RPM
3. Configuration
loudspeaker

of

the

latestprototypeFig. 5 shows the latest, dual motor model.
Two motors are introduced to achieve linear
modulation and cone type radiator is connected
to give reciprocal motion. Frequency
modulation is chosen to control the motor3.
One motor is bolted on to solid base to givebias rotation and the other motor is connected
directly to the same shaft and is also linked tothe cone radiator. The second motor is counter
driven at the same speed as the first to keep thecone stationary. When either or both motor(s)is(are) modulated by audio signal, the linear
region mentioned above is utilized to move thecone. This approach is named as the dual motor
de-spin model.
The frequency characteristics of the dual
motor de-spin model loudspeaker is comparedwith that of a conventional dynamic modelusing the same cone in Fig. 6. The dual motor
de-spin model outperforms in low frequency
region.

Fig 6

Output sound pressure frequency response

4. Conclusion

The dual motor de-spin model which utilizes
two ultrasonic motors was proposed,
prototyped and demonstrated its practicality.
This loudspeaker is useful for low frequency
sound reproduction.
Further study will be carried out in order toimprove performance by re-examining the rolesof two motors and the connecting mechanism
between them.
References:
1. J. Ohga, H. Negishi, T. Sashida, K. Maeda:“A loudspeaker utilizing ultrasonic motor”,
JASJ Vol.62, No.11. P813-818, 2006
2. T. Kenjo, T. Sashida: “Introduction to
Ultrasonic Motor” Oxford Press
3. J. Ohga, H. Negishi, K. Maeda: “A novel
speaker driven by Ultrasonic motor”, Special
presentation, Spring conference, 2008 The
Oceanographic Society of Japan,

3P8-22

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 495- 496
11-13 November, 2008

Evaluating the Efficacy of Counterweight Structure in
Improving the Performance of Linear Ultrasonic Motors
Chaodong Li† and Jian Jin (School of Mechanical & Electronic Engineering andAutomation, Shanghai University, China)
1. Introduction
Linear ultrasonic motors have a very good
application value for high precision mechanisms.
With the development of science and technology,
humanoid robots, insect robots, precision machinesand biogenic medical devices need the actuators as
small as possible. Currently, many kinds of linear
ultrasonic motors have been developed. Because of
the large transverse dimension, it is difficult to be
used in reality. There are only a few miniaturized
piezoelectric linear ultrasonic motors that based onresonance principle. Such as P-653 motor (PI Co.,
Germany), SQUIGGLE motor (New Scale Co.,
USA), L1B4 motor [1] and two types which areproposed by the authors [2,3]. According to theauthor’s experience, the smaller the motor is, theworse the output characteristic is. The main reason
is that the transverse vibration strength which is theacceleration altitude is not enough. The Langevintype transducer is mature enough and has been
widely used in the field of ultrasonic engineering. It
can amplify the output amplitude through theconcentrator. In order to increase the vibration on
driven side and decrease the vibration on un-driven
side, counterweight structure is applied in thedesign of linear ultrasonic motor by using thestructure of Langevin type transducer for reference.
We hope to find a new way to solve the problem of
linear ultrasonic motor miniaturization mentioned
above.
2. The effect of Langevin type transducer withconcentrator to increase the working end
amplitude
The ultrasonic concentrator (horn) is a part ofpower ultrasonic Langevin type transducer. It is
used to enlarge the amplitude on working end of
ultrasonic transducer. And the efficiency ofultrasonic machining is increased. There are manykinds of concentrators that enlarge the amplitude,
such as conical, exponential, stepped and so on. The
sections of them are all reduced gradually fromjoined end to working end [4]. According to the A.
Iula etc’s work, hollow structure can also enlarge
the amplitude [5]. The ratio of operative side
amplitude to free side one A=v2/v1 is an importantparameter of concentrator. The longitudinal-----------------------------------------------------------† E-mail: eastward@sh163.net

Fig. 1 Examples of first longitudinal vibration mode
Ratios of front and back velocity amplitude are,(a):434/434=1.00; (b):538/374=1.44; (c):987/312=3.16

vibration amplitude ratios are different for the shaft
with different shape. Fig. 1 illustrates the firstlongitudinal vibration modes for different shape.
They all have the same volume. FEM analysis iscarried out. The amplitude ratios are 1.00, 1.44 and3.16 respectively. Langevin type transducer is asandwiched structure. The front metal cover can beused as transmitting ultrasonic energy, while theback one is used as the counterweight. These twoparts are designed in different structures to enlarge
the working end amplitude. The vibration of freeend can be decreased. So does the concentrator
work.
3. The effect of counterweight structure forlinear ultrasonic motor to increase the operativeside amplitude
According to the operation principle of ultrasonicconcentrator, the structure of linear ultrasonic motor
can be modified. With the same free side amplitude,
the operative side amplitude is the larger the better.
A plate type structure is cited here. Fig. 2 (a) and(b) show the first and the second vibration modes
for the plate type oscillator with a dentation in the
middle of the body. The ratio of the operative side
(top of the dentation) amplitude along the anticipant
output direction to the maximum amplitude of thefree sides is defined as the valid amplitude ratio.
The valid amplitude ratios in Fig. 2 are 0.59 and0.33 respectively. After the same counterweight isadded on each side of the body, as shown in Fig. 3,
the valid amplitude ratios are 0.83 and 0.47
respectively. The valid amplitude ratio is increased
for both the two output directions.
A diamond hollow structure is developed(equivalent to add a negative counterweight), as
shown in Fig. 4. The rectangular counterweight isadded on each side of the micro linear ultrasonicmotor. The profile size of the motor is 28 mm×5
mm×7 mm. The operative side is the top of thedentation. Figure 5 gives the non-counterweight
one. Figure 6 gives the solid one with the same
volume and a simple shape. A comparison of thetwo motor structures indicates that the operativeside amplitude of the former motor (Fig. 4) isincreased for both the two driving directions. The
efficiency of structure design is proved. And theoutput characteristics are improved.

Fig. 3 The bending modes of the vibrator withcounterweight
Valid amplitude ratios are, (a):1821/2204=0.83;(b):952/2043=0.47

4. Conclusion
According to the simulation results, the linear
ultrasonic motor with counterweight structure or
hollow structure (negative counterweight) canachieve better output characteristics.
Acknowledgment
This work was supported by the National
High-Tech Research and Development Program ofChina (863 Program) (2007AA04A212) and
Shanghai Leading Academic Discipline Project(Y0102).
References
1. Taegone Park, Beomjin Kim, etc：Jpn. J. Appl.
Phys. 41 (2002) 7139.
2. C. Li, D. Shao and J. Xu ： Proc. of IEEE
Ultrasonics Symposium. (2006) 2265
3. C. Li and H. Yao：Proc. of Actuator 08 (2008)
607.
4. Yiquan Yuan: Principle of Modern Ultrasonics
and Its Applications (Nanjing University, China,1996) p.6. (in Chinese)
5. A. Iula, L. Pareniti, M. Pappalardo and N.
Lamberti：Proc. of IEEE Ultrasonics Symposium.
(2005) 1534.

Fig. 4 The bending modes of the vibrator withrectangular counterweight and diamond hollow
structure(a): relative amplitude in the top of dentation is 1902(b): valid amplitude ratio: 511/1548=0.33

Fig. 5 The bending modes of the vibrator withdiamond hollow structure(a): relative amplitude in the top of dentation is 1919(b): valid amplitude ratio: 400/1884=0.21

Fig. 2 The first and second bending vibration modesof plate shaped vibrator
Valid amplitude ratios are, (a):1800/3036=0.59;(b):1003/3046=0.33

Fig. 6 The first bending vibration mode of plate
shaped vibrator with a simple structure
relative amplitude in the top of dentation is 997

3P8-23

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 497- 498
11-13 November, 2008

Preload Control of High-speed Ultrasonic Actuator andEquivalent Circuit Analysis
高速回転超音波アクチュエータの予圧制御と等価回路解析
Manabu Aoyagi1†, Maiko Seki2, Takehiro Takano2, Hideki Tamura3 and Yoshiro
Tomikawa3 (1 Facult. Eng., Muroran Inst. Tech.; 2 Facult. Eng., Muroran Inst. Tech.;2
Facult. Eng., Yamagata Univ.)†

3 1
室蘭工大 工; 2 東北工大 工; 3 山形大 工）
青柳学 1 ，関舞子 1，高野剛浩 2，田村英樹 3，富川義朗 （1. Introduction
An L-shaped ultrasonic actuator which has
simple preload mechanism using a flat spring has
been proposed and it has high-speed revolution
characteristics.1) High-speed rotation of a rotor
can be realized at low preload, but its risetime
becomes longer. It is hard to make the chracteristicof high-speed revolution with short risetime.
However, if a preload can rapidly change from large
to small for an accelaration phase, the risetime will
become shorter, because the revolution speed andtorque can be changed with the preload.
The purpose of this study is to shorten the risetimeof a rotor revolution by a preload control withmaintaining maximum revolution. This paper
reports some experimental results and equivalentcircuit which can be used on a comartial circuitsimurator and which can consider variable preload.

Fig. 2 Coupled vibration modes.

3. Preload control
The stator is fixed on a support jig with ahinge and a multilayer piezoelectric actuator (MPA)
arranged as shown in Fig.3. The MPA moves thestator and changes preload. Therefore, preload canbe controlled electrically.
Support jig

MPA

Metallic bar

2. Principle and construction
Figure 1 shows the basic construction of
stator of L-shaped ultrasonic actuator. This stator
excites two couple vibration modes of longitudinal
vibration and bending one, as shown in Fig.2. The
tip of stator gives a push to a rotor and it revolves
fast in both directions.
Direction ofpolarization

Preloadpart

Support
part

SUS

GND

PZT

Contact partto rotor

Sin tFig.1 Basic construction of the stator of L-shaped
ultrasonic actuator.

-------------------------------------------------------------maoyagi@mmm.muroran-it.ac.jp

StatorHinge
Fig.3 Construction of an L-shaped ultrasonic actuatorwith preload control MPA.

4. Experimental results
Revolution speed and risetime are changed
by preload voltages which are applied to MPA, as
shown in Fig.4. When preload was 80V, the shortest
risetime was obtained. After many experimental
considers, it was found that the effective drive
method for highspeed revolution with short risetime
was to suddenly drop the preload voltage from 80V
to zero at 92ms after starting. Figure 5 showstransient responses with preload control andwithout one. Their maximum revolution speeds
were almost the same, but the risetime became
shorter by 37.6% compared to without preload
control.

Revolution speed[rps]

160
140
120
100
80
60
40
20
0

Revolution speed

120
100
80
60

Rise time

40
20
0
0

50
100
Preload voltage[V]Rise time[ms]140

Vmean=100[mV]
Imean=8.0[mA](a) Normal force Vn.
(b) Thrust Vt.
Fig.7 Outputs at small preload.

Revolution speed[rps]Fig.4 Revolution speed and rise time as a function of
preload voltage.
150

With control
Vmean=140[mV]
Imean=0.38[mA](a) Normal force Vn.
(b)Thrust Vt.
Fig.8 Outputs at large preload.

100

Without control
50
0
0

4.
0.1

0.2
Time[s]0.3

Fig.5 Comparison of transient response of revolution
speed by presence of preload control.

5.

Equivalent circuit

Several equivalent circuits of ultrasonicactuator have been proposed.2-4) However, theirsimulations are not necessarily easy. The equivalentcircuit of L-shaped ultrasonic actuator is shown in
Fig.6. Friction force and slip are expressed withtwo pair of voltage controlled voltage source anddiode. This circuit can be simulated by acommercial circuit simulator. Preload is expressedby DC power source. By changing the voltage of
the DC power source, revolution characteristics
under preload control will be easily simulated.
Figures 7 and 8 are normal force and thrust to arotor, respectively. In the case of large preload, it isfound that the mean values of normal force andthrust are also large.
StatorPreloadNormalforce

Summary

A rise time can be shorter by an electricalpreload control with maintaining maximum
revolution speed. The proposed equivalent circuit
has possibility to easily simulate the performance of
preload control.
Acknowledgment
This work was partially supported by aGrant-in-Aid
for
Scientific
Research(No.19016001) on Priority Areas No.438 from the
Ministry of Education, Culture, Sports, Science,
and Technology.
References
1. N. Kawashima, et.al: IEIECE Technical Report,
US2006-46 (2006)17.
2. T. Sashida and T. Kenjo: An Introduction to
Ultrasonic Motors (Clarendon Press, Oxford,
1993) p.89.
3. S. Ueha and Y. Tomikaw: Ultrasonic Motors,-Theory and Applications (Clarendon Press,
Oxford, 1993) Chap.7.
4. M. Aoyagi and Y. Tomikawa: Jpn. J. Appl. Phys.
36 (1995) 2752.
Vn

Vt
Rotor

Fig.6 Equivalent circuit which can be simulated on a commercial circuit simulator.

3P8-24

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 499- 500
11-13 November, 2008

A new type of rectangular plate type linear ultrasonicmotor using a double mode piezoelectric vibrator of thefirst longitudinal mode and the first flexural mode
縦１次屈曲 1 次多重モード利用矩形板型超音波モータ
Ryouichi Fukunaga, Kazumasa Asumi, Ryouta Asakura, Yutaka Inada (TAIHEIYOCEMENT CORPORATION)

1. Introduction
An ultrasonic motor (USM) directly drives the rotor
by friction without clutches or brakes, and so ischaracterized by a simple structure and a small size.
By making use of this feature, the USM is finding
such applications as in the vibration compensation
mechanism of a camera.
Of all others, amechanism that combines the first longitudinal andfirst flexural modes with a rectangular plate as
shown in Fig. 1 was proposed by Tomikawa, et al.,1)and has widely been studied using piezoelectric
ceramics2) and single crystals.2) Further, as for thesystem combining the first longitudinal (L1) andfirst flexural (F1) modes, the use of a cylindricalpiezoelectric device was proposed, and progress is
expected in the future.4)
There is, however, no report on the ultrasonic motorusing the multiplex L1 and F1 modes with arectangular plate. If such a motor is realized, it isexpected that we can lower the driving frequency
using a lower order mode, and realize a smaller
sized ultrasonic motor. Here, an ultrasonic motorusing the multiplex L1 and F1 modes with arectangular plate is developed and thecharacteristics are measured.

Fig1. Longitudinal and Flexural modes

2. Determination of side ratio of rectangularplate and the behavior of L1-F1 mode
The study of the multiplex mode vibrator with arectangular plate was analyzed by Jumonji, et al.5)
in detail.
Using the FEM analysis (Piezo Plus of Wave
Research), the authors extracted the aspect ratio
where the L1 and F1 modes of a rectangular platedegenerate. Figure 2 shows the simulation resulton the side ratio vs. the resonance frequency

一将、稲田豊（太平洋セメント株式会社）

assuming L = 20 mm. It was found that thedegeneration occurs at around 70 kHz with W = 21.
For the L1-F1 vibrator using the piezoelectric
ceramics polarized across the rectangular plate
thickness as shown in Fig. 2, the electrodes with
two subdivisions are placed on one side and anearth electrode is placed on the other.
Figure 2 suggests that the degeneration between L1
and F1 modes occurs at the side ratio of around
W/L = 1.05.

Freqency (kHz)

福永 了一‡、浅倉綾太、阿隅

110
100
90
80
70
60
50
40
30
20
10

L1-ModeF1-ModeW
Lat L = 20 mm
0.10 0.30 0.50 0.70 0.90 1.10 1.30
W/L

Fig2. Frequency spectrum of a rectangular plate

In the L1-F1 type USM, a driving chip is mounted
in the one central part of a short side, and there
could be two driving methods of single-phase
driving and two-phase driving. This time, asliding chip is adhered onto the central part of ashort side, and the frequency-speed and thefield-speed characteristics are evaluated with
two-phase driving.
3. Trial fabrication of ultrasonic motor
3.1 Fabrication of an USM sample
A single-plate ceramic material (using the material“NA” of Nihon Ceratec) is used for the
piezo-ceramic vibrator as shown in Fig. 3.
Single-plate ceramic material is processed into aplate of 20 x 18.3 x 3 mm. Silver is applied byprinting for the electrodes with two subdivisions in
the one surface of 20 x 18.3 mm and the electrodecovering the entire area on the other side, and thesample is baked at 850˚C. Then, polarization is
uniformly accelerated by the electric field of 2
kV/mm in the silicone oil of 120˚C to obtain apiezo-ceramic vibrator. The resonance frequency
was 76.8 kHz in the L1 mode and 77.1 kHz in theF1 mode. Alumina ceramic material (A995 of
Nihon Ceratec) of half cylinder type was adopted
for the sliding chip.

characteristics. It is shown that the maximum
force of 2.8 N is obtained with the input of 110
Vrms. From the force-efficiency characteristics asshown in Fig. 6, the maximum efficiency was 1.8%.
7
110Vrms
120Vrms

Efficiency (%)

6
5
4
3
2
1
0

Fig.3 Piezoceramic vibrator(20×18.3×3ｍｍ)

3.2
Measurementofforce-velocity
characteristics
To measure the force-velocity characteristics, thedriving system is prepared by pressure-contacting
the USM onto an alumina plate (processed A995 of
Nihon Ceratec) with the mirror-polished sidesurface of a precision linear table. It is hung witha weight using a fixed pulley, and the position ismeasured using a glass scale (encoder; BL55-RE of
Sony).
4. Experimental results
Figure 4 shows the frequency-traveling speed
characteristics. It is found that the maximum
speed is 130mm/s at the driving frequency of 77
kHz and the two-phase input of 90 Vrms.
Traveling speed (mm/s)

160
140
120
100
80
60
40
Forward direction

20
0
76.3

Backward direction

76.7

77.1
Freqency (kHz)

77.5

Fig.4 Traveling speed vs frequency characteristic（No Load、at 90Vrms input）

Traveling speed (mm/s)

120
110Vrms
120Vrms

100
80
60
40

0
0.0

1.0

2.0
Force (N)

3.0

4.0

Fig.5 Traveling speed vs force
characteristic（at 77kHz）

1

2
Force (N)

3

Fig.6

Efficiency characteristic（at 77kHz）

4

5. Summary
An ultrasonic motor using the L1-F1 mode with therectangular plate is fabricated.
Using a piezo-ceramic vibrator of 20 x 18 x 3 mm,
the maximum speed of 130 mm/s at the input
voltage of 90 Vrms, maximum force of 2.8N at the
input voltage of 110 Vrms gaining the maximum
efficiency of 1.8% are obtained. To improve
efficiency, a newer electrode structure shall beadvised and tested in the future.
Characteristics of the efficiency in this fabricatedmotor is not so high. Therefore, it is necessary toconsider another type of electrode configurationthat enables the longitudinal movement andimprove the efficiency.
The ultrasonic motor of this type is characterized bya simple electrode structure and a relatively low
driving frequency, and will find applications bymaking use of an easily realizable small size.
Therefore, it is expected that the USM with arectangular piezo-ceramic vibrator and the L1-F1
multiplex driving mode will have a promising
future.

Acknowledgement
The discussions with Professor Takano, Tohoku
Institute of Technology, and Professor Emeritus
Tomikawa at Yamagata University are greatly
appreciated. The FEM analysis by Mr. Shunsuke
Tsunoda, Nagaoka University of Technology, is also
appreciated.
References
1.

20

0

2.
3.
4.

Figure 5 shows the force-traveling speed
5.

.Tomikawa, .Ogasawara, .Sugawara, .Chikano,T.Tak
ano,：IEICE trans US87-5 （1987）
Y. Tomikawa, T. Takano and H.Umeda ：Jpn. J.
Appl. Phys. Vol. 31 (1992) pp 3073-3076
H.Tamura, K.Kawai, T.Takano,：Jpn. J. Appl. Phys.
Vol.32, No9B, pp4190-4193
H. Kanasugi, T. Maeno, :ICA 2007, Madrid
ULT-09-015
H.Jyumonji：IEICE trans Vol.53-A No.4 pp176-183

3P8-25

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 501- 502
11-13 November, 2008

Elastic holding mechanism for ultrasonic motors
超音波モータの弾性保持機構
Naotake Inoue‡ and Takaaki Ishii (Univ. of Yamanashi)
井上尚武‡, 石井孝明（山梨大院）

1. Introduction
Basically, ultrasonic motor should be supported
at the nodal positions to avoid vibration suppression.
However, it is very difficult to support ultrasonicmotors because nodal points do not always appear
on their surfaces. Therefore several kinds ofholding mechanisms using rubber are sometimes
employed to isolate motor’s vibration. The rubber
mount mechanisms are relatively easy to design andeasy to use, however the motor’s vibration ispartially suppressed and vibration energy is
dissipated.
In addition, vibration mode willchange and eventually motor characteristics will
deteriorate.
In this report, an effective holding mechanism
using resonance is proposed for the ultrasonic motor.
The holding parts are designed to resonate at thesame frequency as the motor’s one. Hence thismethod can hold ultrasonic motor at the anti-nodal
positions which means ultrasonic motor’s vibration
mode remains unchanged. This kind of trial had
been proposed using longitudinal vibration1). In
this research, both longitudinal and bending
vibrations are designed to be the same resonancefrequencies, and the effect of this holding
mechanism will be discussed.
2. Design of the ultrasonic motor
An ultrasonic linear motor using 1st longitudinal
vibration mode and 2nd bending vibration mode isused in this experiment2,3). Fundamental shape ofthe motor and the longitudinal and bending modes
used for this motor are shown in figures 3 and 4.
By controlling the excitation of these two vibration
modes, we can obtain elliptical motion on the edgeof the ultrasonic motor. Then the ultrasonic motor
will be realized.
The resonance frequencies of the longitudinaland bending vibration modes have to be almost thesame value to obtain elliptical vibration efficiently.
The dimensions of the ultrasonic motor areimportant for the resonance frequencies. Length,
width and thickness have to be optimized to obtain
desired frequencies.
In this experiment, around 50 kHz is employed
for the resonance frequencies to realize small sized
ultrasonic motor. The piezoelectric ceramics will
be bonded onto the stainless steel, and thenunimorph type vibrator will be used for theexperiments. Finite element method (ANSYS) is
used for the design.
3. Design of the holding mechanism
The fundamental design for the holding
mechanism is illustrated in figure 1. Simple
structure having the same resonance frequency as
motor's one is employed. One side of the holding
part is attached to the motor and another side of thepart is fixed. These parts have to be vibrated at
the same frequency and the same amplitude.
Three points on the side of the motor are used forholding the motor as shown in figure 1.

Fig. 1 Fundamental design of the proposed
holding mechanism.
The fundamental holding mechanism is
explained as follows.
For the longitudinal vibration of the motor, twoholding parts attached to the motor perpendicular to
the axial direction vibrate in bending mode
associated with the longitudinal vibration of the
motor as shown in figure 4. A holding partattached to the motor parallel to the axial direction
vibrates in longitudinal mode associated with thelongitudinal vibration of the motor as shown infigure 4.
For the bending vibration of the motor, twoholding parts attached to the motor perpendicular to
the axial direction vibrate in longitudinal mode
associated with the bending vibration of the motor
as shown in figure 5. A holding part attached tothe motor parallel to the axial direction vibrates inbending mode associated with the bending vibrationof the motor as shown in figure 5.
Three contact positions will vibrate in bending

mode which cause contact angle change, the shapeof the holding parts has to be designed as point
contact or line contact. Stainless steel will be used
for the holding parts.

excited in the ultrasonic motor does not affected by
the holding mechanism.

4. Analysis results
The vibration modes were analyzed by using
FEM.
First, an ultrasonic motor was designed to vibrate
both in 1st longitudinal vibration and 2nd bending
vibration at the same frequency. 1st longitudinal
vibration mode is shown in figure 2, and 2nd
bending vibration mode is shown in figure 3.

Fig. 4 Longitudinal vibration mode of theultrasonic motor with holding mechanism.

Fig. 2Longitudinal vibration mode of theultrasonic motor.
Fig. 5 Bending vibration mode of theultrasonic motor with holding mechanism.
5. Future plan

Fig. 3

Bending vibration mode of theultrasonic motor.

These analyses were curried out under theconditions of free. In these analyses, simple
structure of the ultrasonic motor consists of only
piezoelectric ceramics is used.
The ultrasonic motor with holding mechanism isshown in figures 4 and 5. As explained in theprevious section, holding parts vibrate associatedwith the motor's vibration. Since the resonancefrequencies of the longitudinal and bending
vibrations are designed to be the same, vibration

It will be necessary to fabricate the ultrasonicmotor and the holding mechanism. And thefeasibility of this proposal has to be confirmed.
The ultrasonic motor with unimorph type structure
will be fabricated and will be used for theexperiments. The structure is different from theone analyzed in the previous section, however, theconcept can be applied and the elastic holding
mechanism will be realized.
References
1. Cheol-Ho Yun, Takaaki Ishii, Kentaro Nakamura,
Sadayuki Ueha and Koji Akashi: Jpn. J. Appl.
Phys. 41 (2002) pp. 3261-3266
2. Hideki Tamura, Kyousuke Shibata, Manabu
Aoyagi, Takehiro Takano, Yoshiro Tomikawa,and Seiji Hirose: Jpn. J. Appl. Phys. 47 (2008) pp.
4015-4020
3. Manabu Aoyagi, Fumihiro Suzuki, Yoshiro
Tomikawa and Ichiro Kano: Jpn. J. Appl. Phys.
43 (2004) pp. 2873-2878

3P8-26

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 503- 504
11-13 November, 2008

Design of a Two-dimensional Array of Multi-Degree-of-Freedom
Ultrasonic Micro Motors
多自由度超音波マイクロモータの 2 次元アレイ化設計
Yasuyuki Goda, Daisuke Koyama, and Kentaro Nakamura(P&I Laboratory, Tokyo Inst. of Tech.)
合田泰之、小山大介、中村健太郎 （東工大

1. Introduction
Current applications of Multi-Degree-of-Freedom (MDOF) actuator exist mainly in
manufacturing process such as robot arms andgrippers. Most of these MDOF actuators are basedon electromagnetic force and air pressure.
Meanwhile, ultrasonic type has advantages in silent
operation, simple structure, small size, and having aholding force. Ultrasonic MDOF actuator has been
prototyped using a combination of a longitudinal
vibration and two orthogonal bending vibrations ofa rod[1]. In this study, we propose a simple structureof MDOF ultrasonic actuator suitable forminiaturization into millimeter-size. We previously
proposed the structure of MDOF ultrasonic actuator
suitable for fabricating on a substrate with theminimum number of PZT elements[2] and obtained
three axes rotation of a ball rotor. Also, the authors
investigated the integration of the actuators into 2-Darray, and fabricated an X-Y stage with 2 x 2 array
actuators. But we could not operate each actuator
independently because of the vibration coupling
between the actuators via the substrate. In this paper,
we propose a new structure for decreasing thecoupling and discuss the frequency design of thestator and the array.

精研）

Ceramic cylinder

Four divided electrodes
PZT ring

Substrate
Array

Element
Ceramic
cylinderSubstrate(insulant)
Substrate(metal)Semisphere lens
PZT

WiringElectrodeSide view ofthe element

Fig. 1 Proposed structure of the MDOF ultrasonicactuator and the composition of the array.

2. Structure and operation principle
This actuator consists of a ceramic cylinderand a thin PZT ring fixed on a substrate as shown in
Fig. 1. The PZT ring is uniformly polarized inthickness direction, and its electrode is divided into
four parts. We can excite two orthogonal horizontal
vibrations and one longitudinal vibration as shownin Fig. 2 by selecting the electrodes. The horizontal
vibration is excited by applying anti-phase voltages
on the two electrodes across the cylinder, while thelongitudinal one is stimulated by in-phase drive of
the four electrodes. The substrate has two layers:
upper layer consists of an insulant for making thewiring of all the hot electrodes and lower layer
consists of a metal for the ground connection.
---------------------------------------------E-mail: gouda@sonic.pi.titech.ac.jp

(A)

(B)

Fig. 2 Vibration modes of the stator and how to apply
the voltages to the electrodes to excite each vibration.
(A) shows the horizontal vibration mode and (B) shows
the longitudinal vibration mode of the stator.

3.

Resonance frequency design

There are two steps for designing the array
actuator: first one is stator design and the second
one is de-coupling design. For the stator model
shown in Fig. 3(A), using Finite Element Analysis(FEA), the resonance frequencies are calculated forthe periphery of the lower disk under the fixedResonance frequency (kHz)（1）
Outer diameter of the cylinder（0.7 mm）(ssssF（3）
Height of the cylinder（1.5 mm）

Y
X

(A)
(B)
Fig. 3 Analysis model of (A) the stator and (B) the array.
About the stator model, the round of the PZT is perfectlyin the fixed condition.

condition. The condition is assumed to beequivalent to the case in which the lower disk ismounted on the substrate. Effects of five parameters((1) outer diameter, (2) inner diameter, and (3)height of the cylinder, and (4) thickness and (5)outer diameter of the lower plate (PZT)) on theresonance frequencies are studied. Figure 4 shows
the results. We decided the inner diameter and thethickness of the lower part as 0.4 mm and 0.3 mm,
respectively, from the reasons of fabrication process.
The outer diameter of the lower part is decided as
3.0 mm from the number of the actuators to bearrayed and the substrate size. The other two
parameters are decided under the consideration of
the de-coupling.
Next, we analyzed the vibration amplitudes for X, Y,
and Z directions for 25 stators. When the horizontal
vibration is excited in No. 11 actuator, unnecessary
vibration (X, Y, and Z-vibrations) of other 24
stators reached to 27 %. In the case of longitudinal
vibration excitation to No. 11, unwanted vibration
was 52 %. In the previous structure, there washigher vibration coupling in the case of longitudinal
vibration. These unwanted vibrations are enhancedby the standing wave between the parallel edges ofthe substrate. We changed the length of one of theparallel edges. The results for difficult Xs and Y=0
are summarized in Table 1. The unnecessary
vibration level reduced to 48 % when X=1.5 mm. If
Y is changed to 3.2 mm, the vibration is decreased
to 39 %.
4.

Conclusions
We proposed a new fabrication of the MDOF
ultrasonic actuator and decided sizes of the stator.
From FEA result, unwanted vibrations werereduced by tilting edges of the substrate that had
been parallel.
Acknowledgment
A part of this study was supported by the
Grant-in-Aid for Scientific Research of Japan
Society for the Promotion of Science, #17360038.

Vertival mode
Horizontal mode
[Outer diameter of the lower part]2.0 mm200

3.0 mm

4.0 mm

100

0
0

1
2
3
4
Height of the cylinder (mm)(A)
Resonance frequency (kHz)Z

300
Vertival mode
Horizontal mode

200

[Outer diameter of the lower part]3.0 mm

4.0 mm

2.0 mm

100

0
0

0.1
0.2
0.3
Thickness of the lower part (mm)(B)
Resonance frequency (kHz)（5）
Outer diameter ofthe lower plate(PZT)（3.0 mm）（4）
Thickness of
the lower plate（0.15 mm）

200

[Outer diameter of the lower part]2.0 mm
4.0 mm
3.0 mm100

Vertival mode
Horizontal mode

0
0

0.1
0.2
0.3
0.4
Inner diameter of the cylinder (mm)(C)
Resonance frequency (kHz)（2）
Inner diameter ofthe cylinder（0.1 mm）

300

200[Outer diameter of the lower part]4.0 mm
2.0 mm
3.0 mm100

Vertival mode
Horizontal mode

0
0

1
2
Outer diameter of the cylinder (mm)(D)
Fig. 4 Resonance frequencies against each fourparameters with change of the outer diameter of thelower part.
Table 1 Percentages of unnecessary vibration amplitude
against the excited vibration amplitude with the changeof the substrate length.

(mm)
Y=0

X=0
52%

X=1.5
48%

X=3.2
63%

X=6.4
60%

References
1. Takafumi Amano, et al., Proc. IEEE Int.
Ultrasonic Symp., pp.667-670, 1998.
2. Gouda, et al., IEICE technical report, US-Vol.106,
No. 440, pp. 1-6, 2006

3P8-27

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 505- 506
11-13 November, 2008

A self-running ultrasonically levitated 2D stage
自走式超音波浮上２次元ステージ
Daisuke Koyama† and Kentaro Nakamura (Precision and Intelligence Laboratory,
Tokyo Institute of Technology)†

小山大介 ，中村健太郎（東京工業大学

1. Introduction
Ultrasonically levitated stage utilizing thenear-field acoustic levitation have several
advantages compared with air bearing and magnetic
systems such as a simple configuration, low-profileand silence in operation. The authors have been
investigating the non-contact ultrasonicallylevitated stages: the sliding table with two
triangular cross-sectional beam [1] and thebidirectional slider with the aluminum rectangularframe [2]. In our previous work [3], theultrasonically levitated linear slider for aself-running sliding stage was investigated. This
paper deals with the 2D version of the self-running
ultrasonically levitated stage.
2. Configuration of the stage
We propose the ultrasonically levitated 2D stage,in which the four self-running non-contact
bidirectional linear sliders [3] are installed. Fig. 1
shows the configuration of the element slider. The
slider has a simple structure: it consists of analuminum vibrating plate (30×10×1 mm) and a PZTelement (10×10×1 mm). When the flexuralvibration is excited along the vibrating plate, theslider on the flat substrate can be levitated with thesmall distance compared with the wavelength in air
due to the acoustic radiation force from the own
vibrating plate. The flexural standing wave excitedalong the slider is asymmetric in the length
direction of the slider by attaching the PZT elementon the edge of the vibrating beam, and the soundpressure distribution in the air gap between theslider and the flat substrate is also asymmetric. The
acoustic streaming is induced in such asymmetricacoustic standing wave field, and the slider canmove in the same direction as the acoustic
streaming due to the kinematic viscosity force of
PZT

10air. By changing the driving frequency, the flexuralvibration mode of the slider can be controlled andthe moving direction of the slider can be changed.
The configuration of the proposed 2D stage isshown in Fig. 2. By cutting the 1-mm-width lines
on the aluminum plate (60×60×1 mm), four element
sliders are integrated. In this version, the vibratingplate is a cantilever-type and the PZT plates areattached on the fixed-end of the vibrating plates.
The 2D stage has four linear sliders, two pairs bothin x and y directions, shown in Fig. 1.
3. 2D Stage performance
By controlling the input voltages to each PZTelement, the channels 1 to 4 in Fig. 2, the stage
performance was investigated. When the stage wasset in the guide rail to restrict the stage moving
direction to a linear motion in the x-direction, thestraight back-and-force motion could be achievedby controlling the driving frequencies and input
voltages to the channels 1 and 3. The straightmotion in the y-direction could be also achieved by
the control of the inputs to the channels 2 and 4.
The driving condition of each channel, in which thestage could move in each direction, is summarizedin Table 1. The vibration distribution of the stage
was measured by an LDV in the driving condition
which the stage moved to the positive direction of
the x-axis (Fig. 3). The positions of PZT elements
are also shown. The vibration mode of the vibratingplate on the channel 1 was the lattice flexural modeand the vibration displacement amplitude is larger

Ch3

10
Unit: mmFig. 1 A self-running ultrasonically levitated linear
slider [3].
dkoyama@sonic.pi.titech.ac.jp

Ch2

60
Ch4
1

30

60

Aluminum plate

Aluminum plate11†

精密工学研究所）

PZT

10
1
30

Ch1

z
10
1

y
x

Unit: mmFig. 2 Proposed self-running ultrasonically levitated
2D stage.

Table 1 Driving condition of each channel (○,80Vpp at 69 kHz; △, 80 Vpp at 68 kHz; ×, no
input).

6
5

Ch 2

Ch 3

Ch 4

pos. x-direction

○

×

○

×

neg. x-direction

△

×

△

×

pos. y-direction

×

○

×

○

1

neg. y-direction

×

△

×

△

0

Thrust [mN]

Ch 1

4
3
2

0

20

40

60
80
100
Input voltage [Vpp]

120

140

Fig. 4 The stage thrust vs. the input voltages to thechannels 1 and 3.

Fig. 3 Vibration distribution of the stage at 69 kHz.
than that of the other channels. The vibrating plateon the channel 1 will contribute mainly to the thrustof the stage since the vibration mode on the channel
1 and the moving direction of the stage correspondto that of our previous slider [3] shown in Fig. 1.
Likewise, the thrust forces of the stage moving in
the negative-x, positive-y and negative-y-directions
originate the flexural vibration on the channels 3, 2
and 4, respectively. The difference of eachresonance frequency is attributed to the individual
difference and the bonding condition of the PZT
elements. Under the condition in which the stage
was moved in the positive-x-direction, namely only
the channels 1 and 3 were excited with the same
voltages at 69 kHz, the levitation distance of thestage was measured by using a digital microscope(VH-8000 and VH-Z450, Keyence, Japan). The
levitation distance of 6.3 μm was obtained with the
maximum vibration amplitude of 4.7 μm.
The thrust characteristics of the stage were
investigated in the same condition. The thrust wasmeasured by inclining the stage and balancing thethrust and the fraction of stage’s weight. Fig. 4
shows the relationship between the input voltage
and the thrust. The experimental values and theerror bars indicate the averaged values of 5 times
and the standard deviations. The stage could not be
levitated with the driving voltage under 40 Vpp dueto the small vibration amplitude. When the stage
was excited with the driving voltage of 40 to 80 Vpp,the thrust could be increased with the input voltages.
With over 80 Vpp, the thrust was decreased with theincrease of the input voltage, and the maximum
thrust of 5.3 mN could be obtained with 80 Vpp.
Since the levitation distance increases with the
input voltage, namely the vibration amplitude, theacoustic streaming is decreased and the thrust isalso decreased by increasing the input voltage [1].
In the case that the vibration amplitude is decreased,
the acoustic streaming is also decreased due to theeffect of the viscosity boundary layer. Therefore thethrust of the stage has the optimum value against
the input voltage.
4. Conclusions
The 2D self-running ultrasonically levitated stage
was investigated. The stage consists of four
vibrating plate, which is the same configuration as
our previous bidirectional slider. By controlling the
input voltages of the four channels, the moving
direction of the stage could be controlled. The
levitation and thrust properties were investigated,
and the maximum thrust of 5.3 mN could beobtained with the input voltages of 80 Vpp.
Acknowledgment
This work was partially supported by Fluid PowerTechnology
Promotion
Foundation,
Electro-Mechanic
Technology
AdvancingFoundation and the Ministry of Education, Science,Sports and Culture, Grant-in-Aid for Scientific
Research on Priority Areas, No. 438, 2008.
References
1. Koyama et al.: IEEE Trans. Ultrason., Ferroelect.,Freq. Contr. 54 3 (2007) 597.
2. Koyama et al.: IEEE Trans. Ultrason., Ferroelect.,Freq. Contr. 54 11 (2007) 2337.
3. Koyama et al.: IEEE Trans. Ultrason., Ferroelect.,Freq. Contr. 55 8 (2008) 1823.

3P8-28

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 507- 508
11-13 November, 2008

Effects of Gap Distance on Revolution Speed of
Non-Contact Type Ultrasonic Motor using Flexurally
Vibrating Disk
屈曲振動円板を用いた非接触型超音波モータの回転速度特性に及ぼすギャップ長の影響
Yasuhiro Yamayoshi†, Tomohiro Nakagawa, Hideki Tamura and Seiji Hirose(Facult. Eng., Yamagata Univ.)
山吉康弘†，中川友裕，田村英樹，広瀬精二 （山形大 工）

1. Introduction
Ordinary ultrasonic motors utilize themechanical friction force to get the driving force.
Consequently, they have a disadvantage that thecontact surfaces between the stator and rotor wear
out by friction. On the other hand, we first proposeda non-contact type ultrasonic motor 1). It is notusing the friction force because the rotor rotates in
non-contact with the stator by maintaining the small
air gap between the stator and rotor. Recently, thenon-contact ultrasonic motor with a rotor levitatedby radiation pressure had reported 2). In these
motors, the rotor over the flexurally vibrating stator
rotates by the acoustic streaming induced in the gap
space between the stator and rotor. These arepromising as a long life, high-speed and small-sized
motors. However, the effects of a gap distance on
the characteristics of these motors have been little
investigated in detail. This paper reports the effects
of a gap distance on the revolution speed of the
non-contact type ultrasonic motor using a flexurally
vibrating disk.

shows the structure and driving condition of thestator. The stator is constructed by bonding an
aluminium disk with the same diameter and a
thickness of tA and a lead zirconate titanate (PZT)
disk with a 30 mm outside diameter, 1 mm inside
diameter and 0.15 mm thickness polarized in the
direction of thickness. Four fan-shaped electrodes
for exciting two B13 modes are formed to the undersurface of the PZT disk using bothphotolithography and wet etching techniques. Fig. 3
shows the resonant frequencies of the stators andgap space as a function of the rotor diameter. They
are calculated by the finite element method (FEM)
analysis taking account of the interaction between
piezoelectric materials, structure and the acoustic
space surrounding them. The sound pressure patternin the gap space is illustrated in Fig. 3. According to
the graph, the resonant frequency of the gap spaceis in inverse proportion to the rotor diameter. The
resonant frequencies of the stator with tA = 0.4 mm
Rotor

2. Construction of motor

yamayosi@yz.yamagata-u.ac.jp

Shaft
Dr

Acrylic resingFig. 1 shows the construction of the
non-contact type ultrasonic motor using a flexurally
vibrating disk. The rotor made by an acrylic resinwith 2 mm thickness rotates together with the φ0.9mm shaft supported by the ball bearing and pivot
tip. A gap distance between the stator and rotor canbe adjusted by sliding the shaft up and down. In the
motor with the levitated rotor, the levitating
distance of the rotor depends on the mass of therotor and the vibration velocity of the stator but inthis motor, a gap distance is always kept constant.
Fig. 2 (a) shows the vibration patterns of the stator.
The resonant mode (B13) has three nodal lines andone nodal circle of a 0.85Ds diameter. Twodegenerating resonant modes are driven with thedifferent phases by 90 degrees to excite acircumferential flexurally traveling wave. Fig. 2 (b)------------------------------------------------------------zDs

Gap space
StatorBall bearing
Pivot tip

Fig. 1 Construction of non-contact type ultrasonicmotor using a flexurally vibrating disk.
Aluminium (tA)PZT (0.15t)
PA1√2Vcosω t

15

42°

12.5

PolingElectrodes

4.5

A-mode-√2Vcosω t
B-mode-√2Vsinω t √2Vsinω t(a)(b)
Fig. 2 Vibration patterns (a) and structure and driving
condition (b) of stator.

35

0.5

30

Air gap25

0.4

stators

20

0.3

15
10
10

tA=0.2 mm

g=500 µm

and the air gap are equaled at about Dr = 26 mm.
However, the resonant frequency of the stator withtA = 0.3 mm is not equaled to the air gap resonancewithin Dr = 30 mm. When the resonant frequenciesof the stator and air gap are equaled, the intensesound pressure is caused in the gap space by theresonant effect of the air gap. As a result, it has
been considered that the rotor rotates with a higher
revolution speed 3).
3. Experimental results
The characteristics of the revolution speed atseveral gap distance are measured under theconstant input power (PA1 = 60 mW) using two
stators and the rotors with a different diameter.
Table 1 presents the equivalent circuit constants of
two stators measured under the low vibration
velocity. Fig. 4 shows the rotation energy Er of therotor as a function of the rotor diameter to compare
the experimental results of the rotors with thedifferent diameter. Er is calculated by J(2πΩ/60)2/2,
where J and Ω are moment of inertia andrevolutions per minute of the rotor. The measured
results of the stators with tA = 0.4 and 0.3 mm areshown in Fig. 4 (a) and (b), respectively. In case of
g = 500 and 200 µm in Fig. 4 (a), the maximum
revolution speed is obtained at the rotor of Dr = 26mm. It is considered that the air in gap space isresonating then because the both resonant
frequencies of the stator and air gap are nearly
equaled as shown in Fig. 3. In case of the narrower
gap like 100 and 50 µm, the rotatable range ofrotors extends to a small diameter. In Fig. 4 (b), therotors hardly rotate in case of a 500 and 200 µm gap
Table 1 Equivalent circuit constants of stators.

0.4
0.3

mode
A
B
A
B

1.2
1.0

fr
[kHz]
25.90325.92221.53821.523

Q
106
101
84
82

Capacitanceratio γ
33.5
33.3
33.0
31.3

tA=0.4 mm

200

0.8
100

0.6
0.4

g=50 µm

0.2
010

15 20 25 30 35
Diameter of rotor Dr [mm]Fig. 3 Resonant frequency of stators and gap space
as a function of rotor diameter calculated by FEM.

tA
[mm]

Rotation energy Er [m Nm]

0.6

500

15 20 25 30 35
Diameter of rotor Dr [mm](a)Rotation energy Er [m Nm]

Resonant frequency [kHz]40tA = 0.4 mm

1.2
1.0
0.8

tA=0.3 mm
g=50 µm

0.6
0.4
0.2
0.0
10

100
200
500

15 20 25 30 35
Diameter of rotor Dr [mm](b) tA = 0.3 mm
Fig. 4 Rotation energy of rotor depending on
rotor diameter.

because the stator resonance is not equaled to theresonance of the air gap as shown in Fig. 3.
However, in case of the narrower gap, the rotors
come to obtain a high-speed rotation in a diameterin wide range.
4. Conclusion
The revolution speed of the non-contact typeultrasonic motor using a flexurally vibrating disk
were measured at several gap distance. The resultsof the presented study demonstrated that it isnecessary to satisfy the resonant condition of the air
gap in case of the comparatively wide gap but the
motor with the narrower gap can obtain a higher
speed rotation on the wide conditions.
Acknowledgment
This work was partially supported by Grant-in-Aid for
Scientific Research, 20920023 on Japan Society for
the Promotion of Science (JSPS).
References
1. Y. Yamayoshi and S. Hirose: Technical Report of
IEICE. US91-41 (1991) 15 [in Japanese].
2. J. Saito, J. R. Friend, K. Nakamura and S. Ueha:
Jpn. J. Appl. Phys. 44 (2005) 4666.
3. Y. Yamayoshi, S. Sone, S. Hirose and H Nakamura:
Technical Report of IEICE. US93-46 (1993) 39 [inJapanese].

3J7a-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 509- 510
11-13 November, 2008

A High-Performance Spatio-Temporal Displacement
Smoothing Filter for Myocardial Strain Imaging
心筋歪みイメージングのための高性能の時空間的変位平滑化フィルター
Shuhui Bu1 †, Tsuyoshi Shiina2, Makoto Yamakawa3, and Hotaka Takizawa1(1System Info. Eng., Univ. Tsukuba; 2Faculty of Med., Kyoto Univ.; 3Faculty ofEng., Kyoto Univ.)†

布 樹輝 1 ，椎名 毅 2，山川 誠 3，滝沢 穂高 1
(1 筑波大 システム情; 2 京都大 医学科; 3 京都大 工学研究科）

1. Background
Accurately assessing local myocardial strain is
important for diagnosing ischemic heart diseases
because decreased myocardial motion often appears
in the early stage. We previously proposed a new
method of 3-D myocardial motion tracking andvisualization of the invariant of a full strain tensor
using a 2-D phased array. The feasibilities of the
proposed methods were evaluated by numericalsimulations[1]. However, the strain calculation isvery sensitive to noise, which causes low spatial
resolution in the strain image. For overcoming the
problem, we have proposed a new displacementsmoothing filter based on dynamic gridinterpolation (DGI) method[2] for reducing the noisein strain calculation.
Typically, when the scanning frame-rate is high,the correlation coefficient, which is calculated fromautocorrelation method, will be high. But only
using two consecutive frames’ phase-shift data, thedisplacements’ dynamic range is low. Therefore, thestrain calculation will be affected by the noise. In
this study, in order to improve the accuracy of
myocardial strain imaging, we extend the proposed
DGI method, that more than 2 frames’ data can beprocessed. The displacement vectors are tracked
and smoothed. From the simulation results, we canconclude that our method can provide moreaccurate myocardial strain image.
2. Method
In this system, a 2-D transducer acquires echo datafrom the myocardium by volumetric sector
scanning. Radio frequency (RF) signals for eachscan line are received at all elements in the probe.
The phase-shifts at every measuring point between
several consecutive frames are calculated by the
combined autocorrelation method (CAM) or theextended combined autocorrelation method(ECAM), and the displacement vectors arecalculated by WPGM from obtained phase-shifts.
At the same time, the myocardium meshes are
generated from the segmented myocardial
boundaries, and the displacement vectors in eachmesh's node are interpolated by bilinear
interpolation, and their coordinates are alsotranslated from Cartesian coordinates to cylinder
coordinates. The displacement data is smoothed by
DGI in spatial dimension, and the displacement
data are also tracked and smoothed in temporaldimension. Finally, the strain tensors are calculated
from the tracked displacement vectors for
improving the accuracy.
In the DGI method, the displacement vectors inrall sampling nodes are defined as u = (ur , uc ) ,where ur is radial direction’s displacement
component and uc is circumference direction’s
displacement component. Virtual springs areattached at each mesh node in radial andcircumference directions, respectively. Through thervirtual springs, revising displacements ε = (ε r , ε c )are introduced, and an overall error function isdefined as:nm[e(ε r , ε c ) = ∑∑ (ε r ) 2 + (ε c ) 2
i =1 j =1

i, j

i, j

]

Erri , j
i , j +1
i, j(u ' r −u ' r ) 2
i =1 j =1 2
n m−1

+ ∑∑

[

]

Grci , ji +1, j +1
i +1, ji , j +1
i, j 2(u ' r−u ' r) − (u ' r −u 'r )i =1 j =1 2

n −1 m −1+ ∑∑Ecci , ji +1, ji, j(u 'c −u 'c ) 2
i =1 j =1 2

n −1 m+ ∑∑[]Gcri , ji +1, j +1
i , j +1i +1, ji, j 2(u 'c−u 'c ) − (u 'c −u 'c )i =1 j =1 2

n −1 m −1+ ∑∑where m is the radial direction’s node number, n is
the circumference direction’s node number, andu ' = (u 'r , u 'c ) is the revised displacement vectors.

(a) Ideal radial strain(b) Radial strain of frame 1-2(c) Radial strain of frame 9-10

0.03

Radial strain ε rr

Radial strain ε rr

Ideal
Frame 1-2
Frame 9-10

0.025
0.02
0.015
0.01
0.005
0

P ro file ’s p a th

0

2

4

6

8

10

12

0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0

(d) Radial strain generated fromtracked displacements

Ideal
Tracked dat a

P ro file ’s p a th0

2

Circumferential position (o’clock)

4

6

8

10

12

Circumferential position (o’clock)(e) Profiles of radial strain generated from two consecutive frames.

(f) Profile of radial strain generated from tracked displacements

Fig. 1 Resulting images and profiles

By minimizing the error function, the revised
displacements, which combine original and revising
displacements at each mesh node, are obtained. The
virtual spring’s pseudo-elasticity parameters Ei,jrr
and Ei,jcc control the axial displacement revision.
The pseudo shear elasticity parameters Gi,jrc andGi,jcr control the shear direction’s revising effect.
For further improving the smoothing effect, theelasticity parameters are automatically adjusted
based on the noise level. For displacement data,
because the error fluctuated around the true value, if
the displacement error of one sampling node islarge, the difference between its neighbor’s
displacements will also be large. Based on this, adisplacement error function is defined as
u i , j +1 − 2u ri , j + u ri , j −1 ,σ i, j = rrr

σ cci , j =hri , j + hri , j +1

u ci +1, j − 2u ci , j + u ci −1, j ,hri , j + hri +1, j

σ rci , j = σ rci , j =σ rri , j + σ cci , j .
2hr and hc is distance between adjacent node in radialand circumference direction, respectively. The
pseudo-elasticity parameters for each sampling
node are mapped by sin function from Emin to Emax
based on the above functions as
σ i , j − σ min π
E i , j = sin()( E max − E min ) + E min .
σ max − σ min 2

After the displacement vectors are revised, thedisplacement vectors are tracked by combine
previous and current two frames’ revised
displacement. Finally, the strain tensors arecalculated from the tracked and smoothed
displacement vectors.
3. Simulation
The performance of our proposed method is
evaluated by numerically simulating the short-axis
imaging of a 3-D myocardial model. The hypothetic

infarcted wall is located around 1 to 3 o’clock. The
maximum radial strain in a normal wall is set to be
15% and 5% in an infarcted wall. The total scannedframe number is 30. The short-axis twisting is set to
4.5 degrees. The 2-D transducer’s outer diameter is
20 mm. The ultrasonic pulse has a center frequencyof 3.75 MHz, and the fractional bandwidth is 40%.
The signal-to-noise ratio is set to 10 dB. The
optimized pseudo-elasticity parameters, which
control the smoothing, are set in the range of 20 to2800 in the radial direction and 20 to 800 in theshear direction.
4. Results and Conclusions
The resulting images and profiles are shown in
Figure 1. Figure 1(a) shows the ideal radial strain.
Figure 1(b) shows the radial strain generated fromframes 1-2, and figure 1(c) shows the radial strain
generated from frames 9-10. Figure 1(d) shows theradial strain generated from tracked displacements.
Figure 1(e) shows the profiles of radial strain
generated from consecutive two frames, and figure
1(f) shows profile of radial strain generated fromtracked displacements. The average accuracy ofimages generated from consecutive two frames is60.27%, and the accuracy of image (d), which is
generated by our proposed method, is 33.50%.
From the resulting images and evaluating
parameters, we can see that even the SNR is low,
our proposed method can output accurate and stable
myocardial strain image.
References
1. N.Nitta and T. Shiina, 2003 IEEE Ultrasonics Symp.,
pp. 1258-1261.
2. S. Bu, T. Shiina, M. Yamakawa, and H. Takizawa:
IEEJ Transactions, pp.1732-1742, vol.127, no.10,2007.

3J7a-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 511- 512
11-13 November, 2008

Examination of Parameters Depending on
Scatterer Density for Quantification of Liver Fibrosis
肝線維症の定量化のための散乱体密度に依存するパラメータの検討
Hiroshi Eduka1‡, Tadashi Yamaguchi2, Naohisa Kamiyama3, and Hiroyuki Hachiya4(1 Graduate school of Advanced Integration Science, Chiba Univ.; 2Resarch Center for
Frontier Medical Engineering, Chiba Univ.; 3Toshiba Medical Systems Co.; 4Graduate
School of Sci. and Eng., Tokyo Institute of Technology)
江塚大史 1‡，山口匡 2，神山直久 3，蜂屋弘之 4（1 千葉大 融合科学; 2 千葉大 CFME;
3
東芝メディカルシステムズ; 4 東工大 理工）

Various studies about tissue characterization(TC) that used probability density function (PDF)of echo envelopes have been performed1. In thecase of enough scatterer density, such as the normalliver tissue, the PDF of echo envelopes can beapproximated by Rayleigh distribution. On theother hand, in the heterogeneous medium, such as
the liver fibrosis, the PDF of echo envelopes will
not obey Raylergh distribution. In this case, it is
known that the PDF can be approximated by K,
Weibull or Nakagami distribution. However, it isdifficult to characterize tissue properties by only
these distribution functions.
In this research, we examined relationships
between the scatterer density and the PDF of echo
envelopes of heterogeneous medium with computer
simulation and in vivo data. Parameters to estimate
scatterer density of fiber tissue is calculated by Q-Q
probability plot in simulation data, and we
examined possibility of the quantification of theactual liver fibrosis.
2.

2Introduction

Quantitation method of heterogeneity

Generalization of amplitude characteristic
evaluation of echo envelopes was tried by thecomputer simulation. Simulation models were madeby mixing a high scatterer density part of 20-200
scatteres/resolution-cell that assumed fiber tissue tothe medium of density enough to generate thespeckle (10 scatters/rc). As a result, the fiber tissue
and the normal liver which generates a speckle
were intermingled. The mixture rate of the highdensity part is 8-40% in the whole of ROI. The
amplitude characteristic of echo envelopes wasderived from the result of Q-Q probability plot. In-----------------------------------------------------------eduka@graduate.chiba-u.jp

10-1highestmixture rate

Y

1.

Rayleigh-2-3

lowestmixture rate-4-5
- 2 .5-2- 1 .5-1- 0 .50

R a y le ig h
8 .0 %
1 2 .0 %1 8 .0 %2 4 .0 %3 0 .0 %4 0 .0 %0 .5
1XFig.1 Results of Q-Q probability plot in simulation
data of homogeneous and heterogeneous media.
Q-Q probability plot, Rayleigh distribution isexpressed by the straight line with the gradient of
two2,3.
Figure 1 shows the results of Q-Q
probability plot in the case of 60 sc/rc were mixed
in homogeneous media with different mixture rate.
The value of curvature of the results of Q-Q
probability plot was increased with rise of the
mixture rate of the high scatterer density part. It isthought that change of the value of curvature inchange of the rate of the signal of a high echo to thesignal of a low echo which constitutes a speckle.
Then, we approximated the result of the Q-Q
plot in two different straight lines, and proposed
those slopes and intersection coordinates as indexesof the mixture rate of a high echo signal. The slopes
was calculated by tan 1 1 in low amplitude partand tan 1

2

in high amplitude part (Fig.2).

probability density

intersection
coordinate

1
2

Q-Q plot
Approximated line
( low amplitude part )Approximated line
( high amplitude part )normalized amplitude

Fig.2 Parameters which evaluate a mixture rateof high scatterer density part.
3. Evaluation
simulationofparameters

bycomputerFigure 3 shows change of parametersaccompanying change of the rate of mixture of ahigh scatterer density part (60 sc/rc). The slope of
low amplitude part decreased slightly with increaseof the mixture rate. On the other hand, the slope ofhigh amplitude part decreased greatly with increaseof the mixture rate. It has high correlation withintersection coordinates, and these parameters had
special combination corresponding to the mixture
rate of high scatterer density part.
These features were similarly observed, whenchanging scatterer density from 20 to 200
scatters/resolution-cell at a fixed mixture rate.
4.

(a)
(b)
Fig.3 Change of the parameter accompanying themixing rate of high scatterer density part (60scatters/rc). (a) Change of slope. (b) Change ofintersection coordinates.
mixture rate, and showed the combination of therespectively characteristic parameters. It is thoughtthat the stage of liver fibrosis can be quantified byestimating the scatterer density by using the
combination of these parameters.
References
1. Maartje M. Nillesen, et.al. : Ultrasound Med.
Biol. 34 (2008) 674.
2. T. Yamaguchi, H. Hachiya, et.al. : Jpn. J. Appl.
Phys. 44 (2005) 4615.
3. H. Yamada, et.al. : Journal of Hepatology 44(2006) 68.

Application to in vivo data of liver fibrosis

The combination of the parameter determinedby the simulation was applied to clinical data. Echodata sets (in vivo) of liver fibrosis were classified by
Shin-Inuyama classification as the result of biopsy.
Figure 4 shows the original echo data sets
and results of applying our estimation method withfour parameters. The result which the part presumed
to be high scatterer density as compared with the
speckle was dyed red is shown below to the original
data of each degree of pathological change advance.
In F0 which is normal liver, the dyed part isonly walls of portal veins or a vein. In F1 in earlystages of a pathological change, a small number ofdyeing part is observed in the edge andparenchymatous part of liver. The quantity of thedyeing part increased and diffused with advance ofa pathological change as same as the feature of liver
fibrosis.

F0

F1

F3

F4

F2

5. Conclusion
From the result of simulation, the parameters
obtained from Q-Q probability plot changed
depending on the scatterer density and theFig.4 Parametric imaging for liver fibrosis.

3J7a-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 513- 514
11-13 November, 2008

Measurement of Scatterer-Size Dependent Frequency
Characteristics of High Frequency Ultrasonic Echoes
for Assessment of Red Blood Cell Aggregation
赤血球凝集度評価を目指した超音波散乱波の周波数特性の散乱体サイズ依存性の計測
Nobutaka Saitoh1†, Hideyuki Hasegawa2,1 and Hiroshi Kanai1,2 (1 Graduate School ofEng. Tohoku Univ.; 2Graduate School of Biomedical Eng., Tohoku Univ.)
齋藤靖好 1，長谷川英之 2,1，金井 浩 1,2 （1 東北大院 工; 2 東北大院 医工）

1. Introduction
Red blood cell (RBC) aggregation, which isone of the determinants of blood viscosity, plays animportant role in blood rheology. RBC aggregation
is formed by adhesion of RBCs because
electrostatic repulsion between RBCs weakens asprotein and saturated fatty acid in blood increase.
Excessive RBC aggregation promotes various
circulatory diseases in the clinical situation, such as
atherosclerosis, hypercholesterolemia, diabetes,
thrombosis and so on [1,2]. Therefore, noninvasive
assessment of RBC aggregationis highly required.
The purpose of this studyis to establish anoninvasive and quantitative method for assessmentof RBC aggregation.

2. Method
RBC is a very small ultrasonic scatterer
whose radius is 4 μm at most, and amplitudes ofscattered RF echoes are very small. To assess thelevel of RBC aggregation, the power spectra ofechoes are calculated using the fast Fouriertransform (FFT) and the RF echoes are analyzed in
the frequency domain.
The spectrum of nonaggregating RBCs obeys
Rayleigh behavior [3,4], which means that thepower of scattered wave is proportional to thefourth power of frequency. By dividing themeasured power spectrum by that of echo from asilicone plate, the frequency response oftransmitting and receiving transducer are removed
from the measured power spectrum [5]. Then, thefrequency range used for normalization wasdetermined because the ultrasonic pulse used in thisstudy has a finite frequency band width. The
reproducibility function γˆ 0 ( f ) 2 [6] is used todetermine the effective frequency band of thetransducer.
-----------------------------------------------------------E-mail:nsaitoh@us.ecei.tohoku.ac.jp

Fig. 1. (a) Power spectrum from Silicone plate, (b) The
reproducibility function.
Mγˆ 0 ( f ) =2∑ Si ( f )

2

,

i =1

M

M ∑ Si ( f )

(1)

2

i =1

where S i ( f ) and M show the power spectrum of
an RF signal and the number of acquisitions of RF
signals, respectively. Figure 1(a) shows the power
spectrum that is averaged over 100 power spectra
S i ( f ) of RF signals from a silicone plate, and Fig.
1(b) shows the reproducibility function γˆ0 ( f ) 2 .
The frequency band, in which the reproducibility
function was greater than 0.9, was used fornormalization.
In Rayleigh scattering, the normalized power
spectrum changes linearly with respect to thelogarithmic frequency and scatterer’s effective
radius can be estimated from the intercept. In
non-Rayleigh scattering, on the other hand, thespectral slope decreases as the scatterer’s effective
radius increases. Therefore, it is possible to assess
the RBC aggregation from the spectral slope andintercept value.

3.

Basic experiment using microspheres

The employed ultrasound diagnostic system(UD-1000, Tomey, Japan) was equipped with amechanical scan probe at a center frequency of 40
MHz (wavelength λ is about 40 μm). Ultrasound RF
echoes were acquired at a sampling frequency of 1

Table 1. Microspheres’ diameter and experimental results.

Therefore, the spectral slope of echoes from RBC
was close to that of microsphere (1) and (2). These
results show that the Spectral slope is related to thescatterer’s radius.

Fig. 3. (a) Power spectrum obtained for the vein, (b)Normalized power spectrum and least-mean-squared
regression lines.
Fig. 2. (a) Power spectrum obtained for microspheres,(b) Normalized power spectrum and least-mean-squared
regression lines.

GHz and 100 power spectra were averaged toreduce the influence of noise. Table 1 shows
measured objects which have deferent scatterers’
radius. These microspheres simulated RBC andRBC aggregation. Figure 2(a) shows the averaged
power spectra of echoes from the microspheres.
Figure 2(b) shows the normalized power spectrum.
The spectral slope and intercept values were shownin Table 1. In Fig 2(b), the normalized power
spectrum of a larger scatterer showed smaller
spectral slope.
4.

In vivo experiment

Figure 3(a) shows the power spectrum fromthe lumen of the vein at dorsum manus of a23-year-old healthy male and Fig. 3(b) shows thenormalized power spectrum and least-mean-squared
regression line. The spectral slope and intercept
were determined to be 3.75 and -27.6, respectively.
RBC diameter is 8 μm at most and this value ofradius is between those of microspheres (1) and (2).

5.

Conclusion

The effective radius of nonaggregating RBC
was estimated in vivo using spectral parameters.
The increase of scatterer’s radius led to decrease of
the spectral slope. These results show the possibilityof the proposed method for the assessment of RBC
aggregation.
Acknowledgment
We would like to appreciate Tomey corporation for
their cooperation on the use of the diagnostic
equipment.
References
1. D. G. Paeng, et al.: Ultrasound Med. Biol. 30 (2004)
45.
2. A. Amaratene, et al.: IEEE Ultrason. Symp. (2005)
874.
3. M. F. Insana, et al.: J. Acoust. Soc. Am. 87 (1990)
179.
4. G. Cloutier, et al.: J. Acoust. Soc. Am. 122 (2007)
645.
5. F. L. Lizzi, et al.: J. Acoust. Soc. Am. 73 (1983)
1366.
6. H. Kanai: Spectrum Analysis of Sound andVibration (Corona Publishing Co., Ltd., Tokyo,
Japan, 1999) (in japanese)

3J7a-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 515- 516
11-13 November, 2008

An analysis of the pulse wave for the blood vessel evaluation
血管壁評価に向けた脈波解析
Masashi Saito†, Mami Matsukawa, Yoshiaki Watanabe (Doshisha University)
齋藤雅史‡，松川真美，渡辺好章（同志社大）

Introduction

The pulse wave is the displacement wave caused by the
inner pressure wave which propagates in the blood vessel.
This pressure wave is composed of the incident wave andthe reflected wave. The incident wave is a pulsed wave
caused by the blood flow which comes from theconstriction of the heart. The reflected wave is generated
by the reflection of the incident wave at the peripheralarteries. Because the reflected wave propagates to theperipheral artery, it strongly depends on theviscoelasticity of the vessel wall. Therefore, theevaluation of the blood vessel seems possible by using
this reflected waveform. The incident waveform
becomes important to estimate the reflected wave.
Figure 1 shows the outline for the estimation of theincident wave.
At first, the changes in sectional area of the bloodvessel were estimated as a function of time with theobserved blood flow velocity waveform. Here, theequation of continuity and the motion equation of one
dimension fluid model was used[2]. Next, the waveformof inner pressure was presumed from the relationshipbetween changing sectional area and pressure in the
blood vessel[2]. To convert from the inner pressure todisplacement, generalized Voigt model was used. In thiscase, the viscoelastic shear properties were obtained
from the reference[3]. The senior subjects' shear elasticity
constants were estimated 2.5 times with the value ofyoung subjects. After the estimation of incident wave,--------------------------------------------------------------------mmatsuka@mail.doshisha.ac.jp

Amplitude

Generalized
Voigt model

Amplitude

Continuity equation
Motion equation

Time

Time

Time

The blood flow

Inner pressure

Displacement(Incident wave)

Amplitude(i) Estimation of the incident wave.

Time

The observed pulse wave
Amplitude

2. Methods
Signal Processing and Computational Techniques

the reflection waveform was obtained from thedifference between this incident wave and the observed
pulse wave.

Amplitude

Arteriosclerosis disease has become a problem in thisaging society. The pulse wave velocity (PWV) method is
one of the diagnostics techniques for arteriosclerosis
under the incipience condition[1]. The velocity of thepulse wave which propagates in the blood vessel wall isanalyzed with this technique. This is because viscoelastic
characteristics of the blood vessel change by thearteriosclerosis disease[1]. In addition to the velocitychanges, the pulse waveform itself changes due to theviscoelastic characteristics. This change of the waveform
is not mainly used now. We then focus on the changes of
the waveform to extract wave information of theviscoelastic property of the blood vessel. Of course, ourpurpose is to screen the symptom of incipient
arteriosclerosis by the pulse wave. Therefore, we suggest
a simple technique for the evaluation of the wave.

Amplitude

1.

Time

Time

Incident wave
Reflected wave(ii) Separation technique.
Fig.1 Estimation of the reflected wave.

Measurement of the pulse wave and Blood Flow
The electrocardiogram and the pulse wave at the leftcommon carotid artery of the healthy young subjects (10persons) and senior subjects (7 persons) were measured.
Figure 2 shows the measurement system. A mechanocardiogram system (FUKUDA DENSHI, MES-1000)
was used for the measurement. The electrode wasinstalled on both hands and feet to measure theelectrocardiogram. The amorphous pulse wave sensor(FUKUDA DENSHI, TY-501A) was used to measure thepulse wave. To measure these data during the restingstate, subjects refrained from meal, exercise and smoking.
They got lying down for ten minutes in the room at 22℃.
Then, the measurement was started. The measurement
period was 60 seconds.
After the pulse wave measurement, we measured anelectrocardiogram and the blood flow velocity at leftcommon carotid artery during the resting state. A probe(TOSHIBA, PLT-1204AT center frequency 12MHz) of
ultrasonic diagnostic equipment (TOSHIBA, Aplio
SSA-700A) was used for the measurement. The
measurement period was 5 seconds.

Transducer

3.
MES-1000
A/D converter

PC

ECG

200mV

Fig.2 Measurement system.

Normalized amplitude

Voltage

ECG

The pulse wave

Time

500ms

(i) 24 years old.
200mV

Results and Discussion

Figure 3 shows examples of the observed pulse wave.
Figure 4 shows the observed blood flow velocities. The
incident wave was estimated from the blood flow
velocity. The observed pulse waveform was thenseparated into the incident wave and the reflected wave.
Figure 5 shows the results of separated waves
normalized by the amplitude of the incident waves. As
shown in Fig. 5, the amplitude of the reflected wave inthe senior subject is larger than that of the young subject.
This tendency was similar with the data of other subjects.
Because senior subjects' vessel walls seem to be harder,
the influence of the wave attenuation is probably small.

ECG

Observed pulse wave
Estimated incident wave
Estimated reflected wave

1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0

Voltage

Time

Time

500ms

Voltage

ECG

Blood flow velocity

Time

Blood flow velocity 20cm/s

100mV(ii) 73 years old.
Fig. 3 Observed waveforms of the pulse wave.

150ms

ECG

Blood flow velocity

Blood flow velocity 20cm/s

100mV(i) 24 years old.

Time
150ms
(ii) 73 years old.
Fig. 4 Observed waveforms of blood flow velocity.

Normalized amplitude

The pulse wave

Voltage

200ms(i) 24 years old.
Observed pulse wave
Estimated incident wave
Estimated reflected wave

1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0

Time

200ms

(ii) 73 years old.
Fig. 5 Results of wave separation.

4.

Conclusion

A simple technique to evaluate the pulse wave is
proposed. From the comparison between young andsenior subjects, we found changes in the reflected wave
due to the age. The viscoelastic characteristics of theblood vessel wall changes owing to the age. Therefore,
there is a possibility that the property of the vessel wall
can be evaluated with this simple technique.

References
1. W. W. Nichols, “McDonald’s Blood Flow In Arteries,”
Hodder Arnold, 2005.
2. T. Kitawaki, et. al. “The analysis of upper arm pressure
pulse waveform if the systemic artery using the onedimensional numerical model,” JSFM, C2-1, 2004.
3. N.Katakura, et. al. “The effect of molecular weight ofpolymer on viscoelastic properties of tissue
conditioners,” JSDMD, 7(3), 439-443, 1988.

3J7b-1

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 517- 518
11-13 November, 2008

Micro bubble adhesion to target wall by ultrasonic wave
frequency sweep method
超音波の周波数走査法によるターゲット壁への微小気泡の付着
Yoshiki Yamakoshi†, Takashi Miwa (Graduate school of Eng., Gunma Univ.)
山越芳樹‡，三輪空司（群馬大院工学研究科）

1. Introduction
Permeability enhancement that promotes drug
injection through cell membrane by ultrasonic wave
is an useful means in future drug delivery system
which uses micro bubbles as payload vehicles.
Mechanical effects such as surrounding liquid flowwhich is caused by micro bubble forced oscillationand micro jet which is produced by bubble
destruction enhance the permeability of the cell
membrane. Since these effects increase in thevicinity of the bubble, the bubbles are placed close
to the surface of the target in the permeability
enhancement. In addition, the bubbles have to cover
over the target surface because the mechanicaleffect of one bubble is spatially restricted. Group of
UC Davis has proposed a sophisticated method
which adheres micro bubbles to the blood vessel
wall using ultrasonic traveling wave1). This method
has a feature that the bubble adhesion is carried out
mechanically by an acoustic radiation force,
however the bubbles adheres only to the wall oftraveling direction of the ultrasonic wave in thismethod.
We have proposed a method of self-adhesion of
micro bubbles to the target wall using ultrasonicpumping wave2). The acoustic radiation force
between actual bubble and the mirror bubble, which
is produced by bubble nonlinear oscillation, acts as
a trapping force to the bubble.
In this paper, a method of micro bubble adhesion
to the target wall by frequency sweep of thepumping ultrasonic wave is proposed.

Pumping US wave (f1)Targetwall

Bubbles
Pumping US wave (f2)e-mail:yamakosi@el.gunma-u.ac.jp

λs1

λs2

(c)

(d)

Fig.1 Bubble adhesion to target wallby frequency sweep of ultrasonic pumping wave.

(Fig.1 (b)). The secondary Bjerknes force alsoaligns the bubbles with almost the same interval.
This interval relates with the wavelength of thesecondary wave radiated from the bubbles (Fig.1(c)). Then, the frequency of the ultrasonic pumping
wave decreases from frequency f1 to f2 (f2<f1).
Since the frequency of the secondary ultrasonicwave decreases from nf1 to nf2 where n is order of
harmonic wave, the interval between neighboring
bubbles expands with the expansion of the
wavelength of the secondary wave (Fig.1 (d)). A
large amount of bubbles reaches the target wall by
repeating the procedure which consists of thefrequency sweep from f1 to f2 followed by rapid
frequency change from f2 to f1.
Bubble2. Bubble adhesion to target wall by ultrasonicwave frequency sweep method
Figure 1 shows basic idea of proposed micro
bubble adhesion by frequency sweep of ultrasonicpumping wave. First, an ultrasonic pumping wave
is applied to the target (Fig.1 (a)). The soundpressure of the pumping wave is chosen lower than
the threshold of the bubble destruction though it isenough to generate a nonlinear vibration of the
bubble. The neighboring bubbles aggregate by thesecondary Bjerknes force which is an acoustic
radiation force between oscillating micro bubbles------------------------------------------------------------

(b)

(a)

-m

-1

0

-L

1

m

x
L

Δx

Target wall
(Boundary)Fig.2 Schematic diagram of the bubble movement
by frequency sweep of the ultrasonic pumping wave.

Let us consider a condition for the bubble toreach the target wall. Figure 2 shows a model underconsideration. We assume that 2m+1 bubbles alignalong x axis and they move either in x or in –x
directions by the frequency sweep. The secondaryBjerknes force FB between two bubbles with aninterval of x is given by 3)

Oscillator

B

Oscillator
CCD Camera
PC

FB ,n = −2π R13 pI 0 Rε ,np1,nxkn sin ( kn x + θ R ,n ) (1)where R1 : equilibrium radius of bubble, pI 0 :sound pressure of the pumping wave, Rε ,n : radialdisplacement of n-th order nonlinear volumetricoscillation of bubble. p1,n , kn = 2π / λn and θ R ,n :sound pressure, wave number and relative phase ofn-th order nonlinear secondary ultrasonic wave,
respectively. In eq.(1), it is assumed that n-th orderharmonic oscillation is dominant among harmonic
oscillations. Since the Bjerknes force is a sinusoidal
function, the bubbles are trapped at the positions
where the following conditions are satisfied.

FB ,n = 0 and∂FB ,n ∂x < 0(2)

From eqs.(1) and (2), interval between theneighboring bubbles Δx is given by

Δx = λn - (θ R ,n 2π ) λn

(3)

If the frequency of the ultrasonic pumping wave
is swept from f1 to f2 where f2<f1, it might beconsidered that the frequency of the nonlinear
secondary ultrasonic wave is swept from nf1 to nf2.
This frequency sweep expands the bubblealignment. The positions of m-th bubble for thepumping wave frequencies f1 and f2 are given by(x ( f ) = m (1 − (θ)
2π ) ) λ

2

R ,n

n ,2

Flow cell
Bubbles :Levovist

Water

Rotary Pump
Ultrasonic wave
transducers

Fig.3

Experimental set-up.

and 40 mm in length. Two concave ultrasonictransducers are adopted to introduce the ultrasonicpumping wave. Dynamics of micro bubbles areobserved by microscope with CCD camera.
Figure 4 shows an experimental result.
Figs.4(a)-(c) are the ultrasonic pumping wave is set
to 3MHz, 3.5MHz and 4MHz, respectively. Fig.(d)is a result of frequency sweep from 4MHz to 3MHz.
An ultrasonic wave contrast agent (Levovist) isused as micro bubbles.
1mm
f=3.5MHz

f=3MHz(b)(a)

xm ( f1 ) = m 1 − (θ R ,n 2π ) λn ,1mMicroscope

f=4MHz(4)

where λn ,1 and λn ,2 are the wavelength of thenonlinear secondary waves, respectively.
From eq.(4), displacement of m-th bubble is⎛ θ ⎞dxm = xm ( f 2 ) − xm ( f1 ) = m ⎜1 − R ,n ⎟ ( λn ,2 − λn ,1 )
2π ⎠
⎝

(5)
Equation (5) shows that the displacement of m-th
bubble increases with increase of number of aligned
bubbles. Once the bubble reaches the target wall, it
is impossible to expand the whole of the bubblealignment any more, because the Bjerknes force
acts as a repulsive force between bubbles. To collectthe bubbles of more amount at the wall, thefrequency is swept from f1 to f2 followed by rapidchange of the frequency from f2 to f1.
3. Experiment
Experimental set-up is shown in fig.3. Microbubble flow cell is 3 mm in width, 1mm in depth

(c)

Fig.4

(d)

Experimental result.

4. Discussions
To concentrate the micro bubbles at the target
wall, frequency sweep of ultrasonic pumping wave
is proposed. Amount of bubbles at the wall
increases by repetition of the frequency sweep.
Experiment is carried out using Levovist micro
bubbles.
References
1. A. Lum, M. Borden, P. Dayton, D. Kruse, S.

Simon, and K. Ferrara: J. Controlled Release111 (2006) 128.
2. Y.Yamakoshi and T.Miwa, Jpn. J. of Appl.Phys.
47 (2008) 4127.
3. Y.Yamakoshi and T.Miwa, Jpn. J. of Appl.Phys.
46 (2007) 4847.

3J7b-2

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 519- 520
11-13 November, 2008

Ultrasound Based Multi-Functional Imaging Using Size
Dependent Characteristics of Phase Change Nano
Droplet
相変化ナノ液滴の粒径による音響特性の違いを用いた多機能
超音波イメージング
Rei Asami†, Takashi Azuma and Ken-ichi Kawabata(Central Research Lab., Hitachi Ltd.)
浅見玲衣‡，東隆，川畑健一 （(株)日立製作所

1. Introduction
Accuracy of imaging based diagnosis could
synergistically
improvewithsimultaneous
allocation of multiple molecular targets.
Concurrent visualization of multiple targets requires
distinguishable probes and an image acquisition
method which can simultaneously handle signals
from each probe. We aim to provide such animage acquisition method with ultrasound and ournovel contrast agent phase-change nano droplets(PCND), submicron sized liquid droplets which
turn into highly echogenic microbubbles uponultrasound pulse application [1]. Combined withreal-time image acquisition of ultrasound scanner,
the method would lead to a clinically applicablemulti-targeted molecular imaging system.
Figure 1 illustrates the basic principle of PCNP
mechanism, which enables localized in-situ
microbubble generation further to be utilized as atherapeutic sensitizer [2] after visualization.
PCND is composed of mixture of low boiling pointand high boiling point perfluorocarbon stabilized bysurfactant lipids and polymers, shown in Fig. 2.
therapeutic US

phase shift US

PCND
Target tissueadministration/accumulation

MicrobubbleImaging ofMicrobubble(diagnosis)

Ultrasoundtherapy withmicrobubble

Figure1: PCND Mechanism
Our aim is to establish either separately
inducibleorvisualize-able
dropletsfor
multi-targeted molecular imaging system byaltering its perfluorocarbon and stabilizing lipids
contents. In this study, we focused on changing
two main parameters, size and perfluorocarbon
mixing ratio, of all parameters possibly affecting

中央研究所）

acoustic characteristics of PCND, and investigatedtheir acoustic characteristics. Specifically, acousticpressure necessary for phase change induction andacoustic response at the timing of and after
microbubble generation are investigated.
Phospholipids
400 nm
Perfluorocarbon
PFC５(C5F12) ＋PFC6(C6F14)

Figure2: PCND Structure

2. Methods
PCND is prepared with varying perfluorocarbon(PFC) mixture and emulsifier at varying PFC toemulsifier ratio, and emulsified at 20 MPa. Laser
diffraction particle size analyzer is used for particle
characterization. PCND dispersion is suspended
in polyacrylamide gel phantom, which is placed inwater bath at 37℃ for ultrasound application at
frequency of 8 and 4 MHz, 4 cycles, and varying
amplitude for phase change induction.
Acoustic
characteristics of induced microbubbles areinvestigated acoustically using pulsar-receiver. For
acquiring acoustic characteristics during phasechange induction, ultrasound at 3.2 MHz, 500
cycles and 85V is used and acoustic response wasgathered by hydrophone.
3.

Results and Disucussion

Two different monodisperse PCND suspensions
were produced with average diameter of 170, and
700 nm (Fig.3). At 4 and 8 MHz, sound pressure
threshold for phase change induction of small
PCND were higher than large PCND by a factor of
1.8 and 1.5, respectively (Fig.4). When resonancefrequency of generated microbubbles is measured,
small group resulted in about 2.8 MHz whereas

Phase Change Threshold(MPa)

Solid line represents small PCND (mean diameter at
170nm) and dashed line represents large PCND (meandiameter at 700nm)
3.5
3
2.5

2
1.5
1
0.5
0

170 nm
700nm

4 MHz

8 MHz

Figure 4: Phase Change threshold for different
sized PCND at 4 and 8 MHz
FFT Spectra of acoustic signal acquired upon
application of phase change ultrasound at 3.2 MHz
are shown in Fig.5. In both small and large
samples, peaks are observed at fundamental
frequency as well as the second and the third
harmonics. Relative amplitude of the second
harmonic components of small group issignificantly higher than that of large group(indicated by an arrow in Fig. 5). 1.5th harmoniccomponent is particular in small group (indicatedby parenthesis in Fig. 5).

Relative Amplitude

1

small
large

0.8

4
3
2
1

0
5
10 15 20 25
Perfluorohexane Content (%)

30

Figure 6:Phase change threshold change
These suggest that phase change could be
induced selectively for different sized PCND
according to the ultrasound amplitude with varying
frequencies. Significant difference observed fromemitted acoustic signal suggests that selective
visualization could be done by appropriate filteringin frequency domain. However, it should be notedthat not just acoustic characteristics but also otherimportant characteristics such as pharmacokineticsof the drug could very likely be altered by size
difference. As a solution, above results suggeststhat alternation of proportion of high boiling point
PFC could potentially function as a mimic of
PCND size difference. Amplitude modulation ofultrasound, thus, has a potential to visualize
distinguishable PCND separately with an adequate
image processing.
Acknowledgment
This work is entrusted by the New Energy andIndustrial Technology Development Organization(NEDO), Japan.
References
1. K. Kawabata et al, Jpn J Appl Phys, 44 (2005)
4548.
2.. S. Umemura, et al, IEEE Trans.
Ultrason.,Ferroelect., Freq. Contr, 52 (2005) 1690

0.6
0.4
0.2
0 0

When the proportion of ultrasonically inactive
high boiling-point PFC (perfluorohexane) is
increased within the same size, the threshold forphase change induction increased dramatically as
shown in fig 6.
Phase Change Threshold (MPa)

Relative Volume (%)

large group resulted in 1.2 MHz, suggesting the size
difference of resulted bubbles.
14
12
10
8
6
4
2
0
0.01
0.1
1
10
Particle diameter（μm）
Figure 3 : Particle distribution of PCND

2.5

5

7.5

10

12.5

Frequency (MHz)Figure 5: FFT Spectra of Acoustic Signal
emitted upon phase change US application

3J7b-3

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 521- 522
11-13 November, 2008

Calorimetric Method for Measuring High UltrasonicPowers Using Distilled Water as the Heating Material:
Eliminating the Effects of Acoustic Streaming, Viscous
Heating and Thermocouple Position
純水を発熱体とする法による超音波
発熱体とするcalorimetry法とするによる超音波パワー
超音波パワー計測
パワー計測
－諸問題を
諸問題を軽減する
軽減する水温測定法
する水温測定法の水温測定法の提案－
提案－
Tsuneo Kikuchi, Takeyoshi Uchida (NMIJ/AIST)菊池恒男，内田武吉（NMIJ/産総研）
1. Introduction

In this paper, we propose a calorimetricmethod for calibrating ultrasonic powers higher
than 100 W. This method is an alternative tousing radiation force balance (RFB) [1,2]. We
report that the ultrasonic power measured using
this method agrees well with that measured by
the primary standard of NMIJ. We also
demonstrate that acoustic streaming, viscousheating and the thermocouple position do notaffect this measurement method.

Fig. 1 shows a schematic figure of theexperimental setup. To avoid multiple
reflections between the water surface and thetransducer, the waterbath was tilted at an angleof about 30 deg., and the reflector was placedon the water surface. A cylindrical waterbath
was used for a 1-MHz, 20-mm-diameter PZTtransducer with an air-backing. The waterbath
had an inner diameter of 150 mm and a depthof 90 mm. The amount of water used was about
1600 cm3. A thermocouple (Takara) was used
to measure the water temperature.
Conventionally, ultrasonic power has been
estimated by taking the derivative of the watertemperature rise as a function of time[4].
However, the time dependence of thetemperature rise, is strongly affected by thethermocouple position (see Fig. 2). As Fig. 2
shows, steep temperature rises are observed at
the time when the ultrasound is switched on(labeled “Ultrasound ON” in Fig. 2). Thisphenomenon is known as viscous heating [3]andiscausedbyultrasonicFig. 1 Schematic diagram ofcalorimetric measurement system.

the2

Ultrasound ON
Temperature rise [deg]2. Experimental method and results

1.5

(a)
(b)

1

(c)

0.5

(d)
(e)

0
150

200

250

300

350

400

Time [s]Fig. 2 Examples of water temperature as afunction of time for ultrasonic irradiation at 1
MHz.
irradiation of the thermocouple. If thethermocouple is placed in the ultrasonic beam,
the temperature rise becomes unstable asshown by curve (a) in Fig. 2. Viscous heating isobserved in the low-frequency range, even

irradiation is defined as the difference between
the two temperatures Tbefore and Tafter.
The ultrasonic power P can be calculated by
the equation (1):

P=(T after-T before)/tx CpM(1)

where Cp is the heat capacity of water (4.2 [JK g-1]) and M is the mass of water. In theactual measurements, t1, t2 and tx are given by
t1=tx=180 s and t2=480 s.
As Fig. 4 shows, the measurement results
at 1 MHz agree well with those of the radiation
force balance method. The two sets ofmeasurements labeled A and B in Fig. 4 wereobtained after performing a full reset of themeasurement
system.
These
results
demonstrate that this method does not require
the thermocouple to be aligned.
-1

Fig. 3 Method of measuring thetemperature rise caused by ultrasonicirradiation.
40

RFB
Calorimetry A
Calorimetry B

Ultrasonic power [W]3530

3. Summary

25
20
15
10
5
0

0

0.05

0.1

0.15

0.2

0.25

0.3

Oscillator output Voltage [V]Fig. 4 Measured ultrasonic power by RFB
and calorimetry at 1 MHz without
multi-reflection.
when the thermocouple is located outside of theultrasonic beam, due to diffraction. To
overcome these problems, we measured thewater temperature before and after ultrasonicirradiation, as shown in Fig. 3.
Ultrasound irradiation begins at a time t1
after the measurement starts. The watertemperature measurement continues for a time
t2 after the irradiation finishes. By assumingthat the drift in the water temperature between
t1 and t2 are sufficiently small, both temperature
variations can be approximated by linear
regression and are extrapolated to the time
when the ultrasonic irradiation finishes. Here,the temperature rise caused by ultrasonicIn this study, we proposed a calorimetricmethod for measuring ultrasonic power thatinvolves measuring the water temperature
before and after ultrasonic irradiation. By using
this method, problems associated withultrasonicradiation
includingacoustic
streaming, viscous heating and setting
reproducibility can be removed. In the future,
we intend to use this method to develop astandard for measuring the ultrasonic power.
References[1] T. Kikuchi, T. Uchida, Proc. Spring Meet.
Acoust. Soc. Japan, 1323-1324, 2008 [inJapanese].
[2] T. Kikuchi and T. Uchida Proc. Autumn Meet.
Acoust. Soc. Japan, 1231-1232, 2007 [inJapanese].
[3] A. Shaw, et al., Ultrasound in Med. & Biol.,Vol.25, No.1 (1999), 121-132..
[4] S. Koda, et al., Ultrasonic Technology, Vol.16,
No.4 (2004) 1-5 [in Japanese].

，

3J7b-4

Proceedings of Symposium on Ultrasonic Electronics, Vol. 29 (2008) pp. 523- 524
11-13 November, 2008

Viscoelasticity Estimation of Soft Tissue for Estimation of Heat
Generation in Application of Ultrasonic Surgical Knife
超音波メス使用時の発熱量推定のための軟組織の粘弾性特性推定
Naoki Suzuki1†, Hideyuki Hasegawa2,1 and Hiroshi Kanai1,2 (1 Graduate School ofEngineering, Tohoku Univ.; 2 Graduate School of Biomedical Engineering, Tohoku
Univ.)
鈴木直貴 1，長谷川英之 2,1，金井 浩 1,2 （1 東北大院 工; 2 東北大院 医工）⎛ ωη ⎞,
θ = tan −1 ⎜2 ⎟⎝ G − mω ⎠1. Introduction
In this study, we investigated the ultrasonic
surgical knife which is one of the medical treatment
technologies with ultrasound. The ultrasonic
surgical knife can cut soft tissues using ultrasoundvibrations and it can cut a soft tissue and stop
bleeding by coagulation at the same time. The
ultrasonic knife can coagulate proteins at acomparatively low temperature compared withother surgical knives such as the laser surgicalknives, and it is a great advantage to prevent
undesirable injury to patients together with theeffect of stopping bleeding. The improvement ofpatients’ QOL (Quality of Life) is becoming more
and more important in recent years [1]. However,effects of the ultrasound vibration of the blade on
the soft tissue have not been revealed thoroughly sofar. The detailed investigation on the influence ofthe tip vibration of the blade would be useful for the
improvement of safety and the optimization ofefficiency of the ultrasonic surgical knife.

The biological tissue is a viscoelastic body,and a mechanical model (Fig. 1(a)) is assumed as amodel of the soft tissue in this report. When an
ultrasonic knife is driven by a simple harmonic
signal, the stress σ also becomes a simple harmonic.
In this case the stress-strain relationship shows ahysteresis property illustrated in Fig. 1(b) because
there is phase delay θ of strain γ from stress σ.
Stress σ and strain γ expressed by the mechanicalmodel are given byγ=

where m, G and η are the equivalent mass, static
elastic modulus and viscosity coefficient,
respectively. When elastic modulus G and viscosity
constant η are estimated, the calorific value and thechange in the stress-stress relationship due totemperature increase can be estimated prior toapplication of the ultrasonic knife by contacting itwith soft tissue.

Fig. 1 (a) Mechanical model. (b) Stress-strain
relationship.

2. Principle

σ=m

(3)

d 2γ
dγ
+ Gγ + η ,
2
dt
dt
σ0

⎛ ωη ⎞
G − mω 2 + ⎜
⎟
⎝ G ⎠

2

sin(ωt − θ) ,

(1)

(2)

------------------------------------------------------------------------E-mail : suzuki@us.ecei.tohoku.ac.jp

3.

MethodIn this study, elastic modulus G and viscosity
coefficient η of an object were estimated byconsidering the equivalent circuit of an object andan ultrasonic knife. Stress σ and strain rate
γ& (=dγ/dt) correspond to the voltage and electric
current in the corresponding electric circuit,respectively. Admittance characteristics Y(ω) of theknife with and without being contacted with theobject were measured using a network analyzer(HP8751A). Equivalent mass m, elastic modulus G
and viscosity coefficient η correspond to themeasured inductance L, inverse of capacitance C
and resistance r of the equivalent circuit of theobject, respectively. The experiments wereconducted for silicone rubber (elastic modulus 48.8kPa) and a soft tissue (chicken breast muscle).

Fig. 2 Experimental setup. (a) End of tip contacts.
(b) Side of tip contacts.
4.

ResultAdmittance characteristics Y(ω) of theultrasonic knife without load, loaded by soft tissue,and loaded by silicone rubber were measured asshown in Figs. 3(a) and 3(b). The changes inresonance frequency f0 and the size of the radius of)
the admittance circle were measured. Resistance ra ,))capacitance Ca , and inductance La of the soft
tissue and silicone were obtained by comparing theadmittance of the equivalent circuit without loadwith that with load.
)
Resistance r)a and capacitance C a of thesoft tissue were estimated to be 15.4 Ω and 1.77 nF,
respectively, and those of resistance r)a and)capacitance C a of the silicone rubber were 20.4 Ω
and 3.75 nF, respectively. The capacitance of thesoft tissue was about twice larger than that ofsilicone rubber. Therefore, elastic modulus G of thesoft tissue was estimated to be 98 kPa by referring
to elastic modulus G of silicone rubber (48.8 kPa)
because the inverse of capacitance corresponds tothe elastic modulus. The estimated elastic modulus
of soft tissue (98 kPa) was in good agreement withthat reported in literature (100 kPa [2]).
The inverse of capacitance and resistance ofsoft tissue when the end of the tip contacted withthe tissue was nearly triple larger than those when
the side of the tip contacted. When the end of the tip
contacted, the tip induced the normal strain in thetissue. Such deformation is dependent on complex
Young’s modulus E+ jλ. On the other hand, theshear strain induced by the contact of the side of the
tip with the tissue was dependent on the complex
shear modulus G+jη. When a material isincompressible, E=3G
and
λ=3η [3].
Theexperimental results showed these relationships
because a soft tissue is almost incompressible.

Fig. 3. (a) Admittance Y(ω) and (b) admittance circle
when the end of the tip contacted. (c) Admittancecircles of chicken muscle when the end and side of thetip contacted.

4.

Conclusion

In this report, the equivalent electricity
resistance, inductance and capacitance of the soft
tissue were measured with a network analyzer. It
will be possible to assess the calorific value in theapplication of an ultrasonic knife by enabling theestimation of viscosity coefficient η by further
investigations.
References
1. T. F. Molnar, et al., Eur. J. Cardio-Thorac. Sung.,
26 (2004) 1192.
2. M. Saitoh, Biological Engineering, Corona
Publishing Co., Ltd, Tokyo, Japan (1985) 17．(inJapanese)

3. T. Nakagawa，Rheology，Iwanami PublishingCo., Tokyo, Japan (1978) pp.22-23. (inJapanese)Author Index
NameAAbe, Koki
Abe, Shogo
Adachi, Takehiko
Aizawa, Shinichi
Akai, Daisuke
Akao, Shingo
Akazawa, Naoto
Akedo, Jun
Akita, Masayuki
Akiyama, Iwaki
Amakasu, Kazuo
Anada, Tetsuo
Ando, Koji
Aoki, Yuichiro
Aoyagi, Manabu
Aoyagi, Seiji
Aoyagi, Takahiro
Arakawa, Mototaka
Asaka, Michinori
Asakura, Naoto
Asano, Yusuke
Azuma, Takashi(* First Author)
Page number(s)

469
115*
205
249*
85
23, 165*, 363
395*
483
199
275, 277
469
313, 477343
209
61, 63, 439
129353*
1, 139213*, 381
303
257
427

B
Bardonnet, Raphaël
Bhuyan, Satyanarayan
Bu, Shuhui

325
169*
423*, 489

C
Cao, Wenwu
Chao, Ye
Choi, Pak-Kon

21
137*
115, 183

D
Dan, Keita
Doshida, Yutaka

371*
481*

E
Endo, Akito
Endoh, Haruo
Endoh, Nobuyuki
Epelbaum, B. M.
Ezuka, Hiroshi

483*
37, 43313, 477
139
411

F
Fan, Honghui
Fujii, Satoshi
Fujimori, Hidetoshi
Fujimoto, Haruhiko
Fukawa, Yasuteru
Fukiura, Takeshi
Fukuchi, Tetsuo
Fukuda, Makoto
Fukuhara, Takashi
Fukushima, Shinichi
Fukutomi, Hiroyuki
Fukuyama, Atsuhiko

227*
259
311
161
207*
363
223*
219*
33
57*
223
57

G
Gao, Qiongyuan
Goka, Shigeyoshi

113*
385

Name
Goto, Nobuo
Gravel, Pierre
Grimal, Quentin
HHa, Euiseong
Ha, Kanglyeol
Hachiya, Hiroyuki
Haino, Ryota
Hamamura, Sunao
Hamaoka, yosuke
Hara, MotoakiHara, Takefumi
Harata, Akira
Hasegawa, Hideyuki
Hasegawa, Takeshi
Hashimoto, Eiji
Hashimoto, Ken-ya
Hashimoto, MasahikoHatake-Yama, Mika
Hatanaka, Kenichi
Haupert, Sylvain
Hayama, Noritaka
Hayashi, Takahiro
Hemsel, Tobias
Higuchi, Kazuki
Hikita, Mitsutaka
Hiraizumi, Yasushi
Hirao, Masahiko
Hirashima, Satoshi
Hirose, Akira
Hirose, Seiji
Hiruma, Yuji
Hohkawa, Koji
Honda, Yoshiaki
Hong, Soon-Min
Honma, Hiroshi
Horinaka, Hiromichi
Hosaka, Hiroshi
Hoshimiya, Tsutomu
Hosoda, Maiko
Hosoi, Hiroshi
Hosokawa, Atsushi
Hosono, Yasuharu
Hotta, Tetsuro
Huynh, Khanh An
Hwang, AnnaI
Ichiki, Masataka
Ide, Kazuki
Ihara, Ikuo
Iida, Yasuo
Ikari, Tetsuo
Ike, Yuji
Ikeda, Takeshi
Ikeshita, Kazuki
Imaeda, Noriyuki
Imai, Masashi
Imai, Takao
Imaizumi, Nobuo
Imano, KazuhikoPage number(s)
237*
325
325*

387*, 389
21, 319
119, 125, 311, 409, 411
257
147
89
153
239
53
413, 429, 431, 433, 435, 487*447*
27, 209*
159
125
37*, 43*
77
325
35*
351*
437
85
99, 37399, 3735, 19, 33, 35, 77, 179
53*
131, 379
61, 63, 481
13, 20183, 91, 95*
133
289
247*
333*
177, 235
37, 43
359*
403
269*
405
23
461
459

431
307
365
135
57
25, 27, 175, 207, 209
161
433*
385*
55, 105
283*
33
219

Name

Page number(s)NameInba, Masafumi
Inoue, Hiroshi
Inoue, Takeshi
Irie, Takasuke
Irieda, Taisei
Ishida, Makoto
Ishihara, Ken
Ishihara, Manabu
Ishii, Masahisa
IshiiI, Ken
Ishikawa, Kiyoshi
Ishikawa, Mutsuo
Ishimaru, Yukihiro
Ishino, Takahiro
Itaba, Masanori
Ito, Hiromasa
Ito, Masayasu
Ito, Mikinori
Ito, Yoshihiro
Ito, Youichi
Itoh, Hideaki
Itoh, Kouichi
Itsumi, Kazuhiro
Iwaki, Masafumi
Iwasaki, Suginori
Iwasaki, Yukio
Iwase, Masashi
Iwase, Ryoichi
Iwata, Naoya

377*
417
147*
273
481
85
407
123
121
469*
243
177*
105
341, 449
17
239
393*
85*
163
303*, 307*
243*
273
405
153
323
89
61*
467*
23, 101, 165, 363JJang, Yun-Seok
Jing, Tian
Jiromaru, Tsujino
Jo, Jung-Lae
Joh, CheeyoungJun, Yang
Jung, Seung-Boo
Junhui, Hu

281*
455
299*
171
319
137, 455
171, 287, 289
169

Kawabe, Masahiko
Kawai, Go
Kawakami, Shyunsuke
Kawamura, Youhei
Kawano, Shuichi
Kawasaki, Hiraku
Kawasaki, Takahiro
Kawashima, Norimichi
Khim, Jeehyeong
Kikuchi, Toshiaki
Kikuchi, Tsuneo
Kim, Jongchan
Kim, Jongtae
Kim, Jungsoon
Kim, Kyoung-soo
Kim, Moojoon
Kim, Young H.
Kim, Yu-Na
Kinugawa, Takaomi
Kishimoto, Sumiaki
Kitamura, Motoki
Kiuchi, Masato
Kobari, Kentaro
Kobayashi, Hideaki
Kobayashi, Hiroyuki
Kobayashi, Kazuto
Kobayashi, Yoshitada
Kodama, Masao
Kogai, Takashi
Kogakura, Jun
Koh, Keishin
Koike, Jumpei
Koike, Yoshikazu
Koizumi, Noriko
Kojima, Seiji
Komuro, Ryoichi
Kon, Akihiko
Kondoh, Jun
Konno, Masahito
Kono, Kenji
Konyo, Masashi
Koo, Ja-Myeong
Koshida, Nobuyoshi
Koyama, Daisuke
Koyama, Mistuaki
Kozuka, Teruyuki
Kubodera, Yu
Kudo, Subaru
Kurosawa, Hajime
Kurosawa, Minoru
Kusakabe, Koich
Kushibiki, Jun-ichi
Kweon, Boyoun

K
Kadota, Michio
Kaga, Shigetaka
Kagami, ToshihikoKake, Yosuke
Kakio, Shoji
Kamada, Rui
Kamada, Yasuhiro
Kamakura, Tomoo
Kamiguchi, Hiroki
Kamioka, Hiroaki
Kamiyama, Naohisa
Kamohara, Akihiro
Kanai, Hiroshi
Kaneko, Shou
Kaneko, Yoshihisa
Kang, Jinwoo
Kang, Kookjin
Kano, Jun
Kasahara, Kei
Kashiwa, Keisuke
Kashiwagura, Nobuo
Katane, Tamotsu
Katayama, Kenji
Kato, Yusi

7, 141, 163*5931
19
79, 93, 203, 239, 257*
107*
215
107
89
199
409
389*
413, 429, 431, 433, 435, 487
361
183
291*
81
175
241
159*
199*
123
49, 51
11

Page number(s)
267
129
333
213, 381, 387, 389
259*
335*
383
117, 271, 369
111, 113, 173, 181, 459, 461
349, 467, 471
109*, 117, 271
173, 459
461
21*, 319*291
21, 319
291
171
435*
481
239*
155
23*
7, 163
55
123
243
207
143*
11
83, 91, 95
67
249
267
25, 27, 175, 207, 209
17
309*
97
401*
333
149
171*, 287, 289
133
167*, 275, 301, 447, 457
253*
135*
295
73*
203*
271, 369, 445*
19
1, 139459*

LLaugier, Pascal
Lee, Jong-Bum
Lee, Phil-Ho
Lee, Seongwook
Li, Haiyue
Lim, Myunghee
Lin, Chundan

325, 327
171, 289*
315
315*, 317, 321
229*
111, 113, 181*, 459
321*

M
Maeda, Makoto

93*

Name

Page number(s)Maeno, Takashi
149
Maezawa, Miyuki
107Mano, Isao265
Masuda, Kohji
283, 407
Masui, Hironari
427*
Masuyama, Hiroyuki
233, 391*
Matsuda, Kenji
141
Matsuda, Tetsuya
329
Matsuda, Yu
207
Matsui, Yoshikazu
97
Matsukawa, Mami
87, 255, 263, 265, 267
Matsumoto, Kazuya
409
Matsumoto, Sayuri
477*
Matsumoto, Takeshi
31*
Matsunaka, Toshiyuki
333
Matsunami, Ken
89
Matsuo, Hiroshi
119*
Matsuo, Takuya
87*Matsuyama, Tetsuya
333
Maxey, Bryan
101
Meguro, Toshihiro
161
Mihara, Tsuyoshi
189
Mikuni, Satoru
97
Minami, Akinari
419
Minami, Keiya
99*, 373
Minami, Yasuo
29*
Minamide, Akiyuki
55
Minamide, Ayumu
231*
Minato, Atsushi
17
Mitton, David
325
Miura, Hikaru
293*
Miwa, Takashi
331
Miya, Naoki
453*
Miyashita, Toyokatsu
195*
Miyazaki, Hisashi
39, 41*
Miyazaki, Yasumitsu
237
Mizukawa, Hirofumi
263
Mizumura, Keiichi
305
Mizuno, Katsunori
265*
Mizuno, Seiji
3*
Mizutani, Keiichi
127*
Mizutani, Koichi
121, 127, 197, 213, 231, 233, 309, 311,
349, 381, 387, 389, 391, 467, 471, 475
Mononobe, Shuji
285*
Moon, Jeong-Hoon
171, 291
Moon, Won-Chum
171
Moon, Young-jun
289
Mori, Kazuyoshi
463*
Mori, Kiyomi
345
Mori, Toshimasa
97
Mori, Yahiro
383
Morimoto, Jun
39, 41Morita, Takeshi
177, 235, 437
Moriya, Tadashi
273, 279, 395, 441, 443
Motoki, Yohei
149*
Motooka, Seiichi
383
Mukai, Tohru
469
Mukaiyama, Takashi
333
Muramatsu, Yusuke
407*
Murata, Takaki
141*
NNa, Seungmin
Nagano, Akira
Nagasawa, Tatsuya

113, 181
263
361

Name
Nagata, Hajime
Nagatani, Yoshiki
Nakagawa, YasuhikoNakamura, Hiroyuki
Nakamura, Kentaro
Nakamura, Naoki
Nakamura, Nobutomo
Nakamura, Toshiaki
Nakane, Tomoo
Nakanishi, Hidekazu
Nakano, Koichi
Nakao, Takeshi
Nakasato, Shingo
Nakashima, Yasuhiro
Nakaso, Noritaka
Nakatani, Shintaro
Nakazawa, Marie
Nam, En Kyu
Naohisa, Kamiyama
Naoi, JunNara, Makoto
Naruse, Kengo
Nemoto, Masahiro
Nishihara, Tokihiro
Nishihira, Morimasa
Nishikawa, Masahiro
Nishimiya, Kojiro
Nishimure, Kazumi
Nishino, Hideo
Nishino, Tomohiro
Nishiyama, Masayoshi
Nitta, Naotaka
Noge, Satoru
Noguchi, Kazuhiro
Noh, Bo-In
NOMURA, Hiroyasu
OOchi, Atsushi
Ochi, Hiroshi
Odagiri, Yoshitaka
Ogasawara, Hanako
Ogata, Takashi
OGAWA, Hideo
Ogi, Hirotsugu
Ohara, Yoshikazu
Ohashi, Toshinori
Ohashi, Yuji
Ohbuchi, Takeshi
Ohgi, Tsuneo
Ohki, Michio
Ohtani, Toshihiro
Okada, Nagaya
Okamoto, Yoichi
Okamoto, Youichi
Okawa, Hirokazu
Okiyama, Yusuke
Okubo, Kan
Okushima, Rimi
Okuyama, Masanori
Omori, Tatsuya
Omori, Toshinobu
Ono, Daisuke
Onodera, Teppei

Page number(s)13, 201
403*
79, 93, 203, 239, 257
89*
69, 71, 167, 275, 301, 343, 353, 371,
447, 457
333
19, 33*, 179*
311, 463, 475
305
89
343
141
213, 381*
323*
101, 103, 165, 363
217*, 485
69, 71*, 353
315
411
187, 473*
97
345*
201*
153
219
341, 451
197*
95
191*
131*, 379*77
415*
205, 241
165, 363
287*
359

147
185, 187, 347*, 465
429*
311*, 463
223
359
5, 19, 33, 77, 179
189*
235*
1, 139*
233*
103
251*
215*
85
39
41
213, 381, 387, 389
97*279, 395, 397, 401, 441
121
129
159
77*
129*
413*

Name

Page number(s)Name

Onoe, Morio
Onose, Yasutaka
Oonishi, Hidekazu
Oosumi, Ayumu
Osawa, Yasuaki
Osugi, Yukihisa
Otani, TakahikoOte, Kazunori
Otonari, Mikito
Otsuka, Hiromi
Otsuka, Tetsuro
Ozaki, Kyosuke
Ozawa, Ayako
Ozawa, Satoru

59*, 193*, 375*
145*
165, 363
303
393
151
265
103
85
47
305*
161
183*
17

Senda, Jiro
Seo, Heeseon
Seo, Kunihiko
Seshimo, Yuichi
Seto, Yuki
Shen, Qing
Shibata, Kyousuke
Shigekawa, Naoteru
Shigematsu, Takashi
Shih, Wen-Ching
Shiina, Tsuyoshi
Shimojo, Yoshiro
Shimura, Takuya
Shin, Hyoyoung
Shin, Yuichi
Shintani, Ryuji
Shintarou, Isa
Shiokawa, Showko
Shirakawa, Takashi
Shiroki, Kenichi
Siginouchi, TakehikoSim, Dongyoun
So, Cheolho
Somatomo, Hiroyuki
Son, Younggyu
Song, Il S.
Sugasawa, Shinobu
Sugawara, Sumio
Sugaya, Nobuyuki
Sugimoto, Tsuneyoshi
Sumi, Chikayoshi
Sun, Xiao-Yun
Suzuki, Kenji
Suzuki, Shin-nosuke
Suzuki, Takanobu
Suzuki, Tatsunori

P
Padilla, Frederic
Park, Beomguk
Park, Ik B.
Park, Kyu-ChilPei, Da Lie
Peifeng, Ji
R
Roh, Yongrae
S
Saida, Kenji
Saito, Hideaki
Saito, Ikumi
Saito, Osami
Saito, Shigemi
Saito, Yuzuru
Saitou, Atsusi
Sakaguchi, Takefumi
Sakai, Hideki
Sakai, Keiji
Sakai, Kentaro
Sakai, Masahiro
Sakai, Taro
Sakamoto, Masanori
Sakamoto, Shin-ichi
Sakamoto, Takashi T.
Sakuma, Masanori
Sasaki, Kazuaki
Sasaki, Yasuhiro
Sasaki, Yasunori
Sasanuma, Keita
Sase, Sadanori
Sato, Akira
Sato, MasahiroSato, Masakazu
Sato, Motoki
Sato, Takashi
Sato, Takayuki
Sato, Toru
Sato, Yuji
Satoh, Yoshio
Satoh, Yusuke
Sawada, Kazuaki
Sawada, Kouichi
Sawada, Tsuguo
Seino, Katuhiro
Sekimoto, Hitoshi
Sekiya, Tadashi

327*
461*
173*
281, 317*
245*
137, 455*

75*, 81*, 245

221
187, 473
121*
123
221*, 275
393
145
403
47
29, 359
57
151
283
267*
341*, 449, 451, 453
473
165, 363*
427
147
323
27*, 209
121
49*
399*
425
199
161
385
329
475*
153
157*
85
469
49, 51
457
385
175

T
Tabaru, Masaya
Tadokoro, Satoshi
Tagawa, Norio
Tai, Tomoyoshi
Takada, Masahiko
Takahashi, Junji
Takahashi, Manabu
Takahashi, Nobuaki
Takahashi, Shin'ya
Takano, Masahiro
Takano, Takehiro
Takatsu, Nobuo
Takatsu, Tomoaki
Takeda, Naoto
Takeda, Nobuo
Takei, Hiroyuki
Takemura, Tsuyoshi
Takenaka, Tadashi
Takeuchi, Nobunao
Takeuchi, Shinichi
Takeyama, Hidenori
Taki, Hirofumi
Takiguchi, Hiroaki
Takiguchi, Norihito
Takimoto, Koki
Takimoto, Mikio
Takizawa, Hotaka

Page number(s)341, 449
319
225*
25*, 27, 209369*
11*, 45, 47*, 49, 5163*
95
437*, 445
261*
423, 489
175
185*, 347, 465
289
477
343
117
143
225
33
125
101*
291
9*
111*, 173, 181, 461
173
211*
65*, 67*31
225, 335
419*, 421*
261
151
123*
375
203

69*, 71, 353
149
279, 395, 401, 441, 443
151*
265
31
365*
9
221
343*
61, 63, 439
247
43
415
101
167, 301*
439*
13*, 201397
117, 271, 369
477
329*
39*
177
99, 373*
343
423

Name
Takubo, Shin-ichi
Tamura, Hideki
Tamura, Kiyoshi
Tamura, Yasutaka
Tanabe, Masayuki
Tanaka, Atsushi
Tanaka, Satoshi
Tanaka, Shinji
Tanaka, Shun
Tanaka, Tomoya
Tanei, Hiroshi
Taniguchi, Shinji
Tanuma, Atsushi
Tao, Hiroaki
Tarumi, Ryuichi
Terao, Yuji
Tetsugi, Ueoka
Tezuka, FumiakiToh, Ryo
Tokunaga, Yoshiaki
Tomikawa, Yoshiro
Tomoda, Motonobu
Touru, Nomura
Towata, Atsuya
Toyoda, Taro
Tsuchiya, Takao
Tsuchiya, Takenobu
Tsuchiya, Toshio
Tsugawa, SaeTsuji, Toshihiro
Tsuji, Yoshiyuki
Tsujimoto, Toshiyuki
Tsujino, Jiromaru
Tsukada, Shinya
Tsukamoto, Akira
Tsurugaya, Yoshiaki
Tsurunari, Tetsuya
Tsutiya, Takenobu
Tsuzuki, Kentaro
Tuziuti, ToruU
Uchida, Takeyoshi
Uchida, Tatsuya
Ueda, Masanori
Ueda, Sawami
Ueda, Takanobu
Ueha, Sadayuki
Ueki, Masashi
Ueki, Takaaki
Umeda, Takatoshi
Uno, Takehiko
Ushida, Takashi
Ushio, Shuki
V
Vastel, Laurent
Voti, Roberto Li
W
Wada, Kenji
Waga, Satoshi
Wakamatsu, Shunichi
Wakata, Tetsuya
Wakatsuki, Naoto

Page number(s)195
61, 63, 439, 481
425
227, 377
279*, 395, 441, 443*
255*
9
7*
297
1*
19*
153
421
5*
5, 35
83*, 91
299
431
383*
55*, 105*61, 63, 439, 481
337*
145
135
11, 45*, 47, 49, 51
397*, 401
313*
187*, 473
45
23, 101, 165, 363
449*
265
295*, 297*
175*
485
349*, 471*
89
477
431*
135

109, 117*, 271
419
153*
407
355*
69, 71, 167, 301, 353, 371, 447, 457
131
229
259
205*, 241*
485
313

325
337

333
161*
253
451*
121, 127, 197, 231, 233, 309, 475

NamePage number(s)Wakatsuki, Noboru
247
Waki, Kohei
195
Wang, Ruiping
175
Wang, Tzyy-Long
261
Wang, Yong
125*
Watabe, Yoshifumi
133*
Watanabe, Shigenori
253
Watanabe, Tokihatu
65
Watanabe, Yasuaki
385
Watanabe, Yoshiaki 87, 217, 255, 277, 341, 449, 451, 453, 485
Watanabe, Yoshitaka
185, 347, 465*
Watanabe, Yuji
345
Winnacker, A.
139
Wright, Oliver B.
337
Wu, Mu-Shiang
261
X
Xie, ShangpingY
Yagi, Shin-ichi
Yamada, Akira
Yamada, Ken
Yamada, Kiyokazu
Yamaga, Mitsuo
Yamaguchi, Masatsune
Yamaguchi, Tadashi
Yamakawa, Makoto
Yamaki, Ryo
Yamakoshi, Yoshiki
Yamamoto, Kana
Yamamoto, Kazufumi
Yamamoto, Ken
Yamamoto, Mariko
Yamamoto, Mitsuru
Yamamoto, Naoki
Yamamoto, Setsu
Yamanaka, Kazushi
Yamanouchi, Kazuhiko
Yamashita, Kaoru
Yamashita, Yohachi
Yamato, Yu
Yamaya, Chiaki
Yamazaki, Kaoru
Yamazaki, Takanori
Yanagida, Hirotaka
Yanagisawa, Takayuki
Yanagitani, Takahiko
Yaoi, Yuichiro
Yasui, Kyuichi
Yatoji, Yoske
Yatsuda, Hiromi
Yin, Fuxing
Yokoyama, Ryouta
Yokoyama, Ryuji
Yokoyama, Tsuyoshi
Yoon, Jong Rak
Yoshida, Kenichi
Yoshida, Kenji
Yoshida, Yukihisa
Yoshimoto, Naoki
Yoshimura, Kazuho
Yoshino, Takafumi
Yoshioka, Masahiro
Yoshioka, Syouhei

441*, 443

425
229, 339*
361*
7
199
159
119, 409*, 411*
423, 489*
379
331*
51*
263*
197
479*
147
79*
189
23, 101, 103, 165, 189, 363
157
129
405*
263
417*
263
83, 91*
227, 377
103*
87, 155*, 255, 263
263
135
339
97, 143
215
425*
191
153
315, 317, 321
191
217, 277, 485*
47
277*
271*
457*
271, 367*
17*

Name

Page number(s)Yoshizawa, Masasumi
Yoshizumi, Natsuki
Yun, Insik

273*
275*
75

Z
Zheng, Kuang

137

ISSN 1348-8236

Proceedingsof Symposium on

ULTRASONICELECTRONICS
Vol. 29

USE2008
The 29th Symposiumon
ULTRASONICELECTRONICS
Nov.11-13, 2008 Sendai, Japan
URL: http://www.use-jp.org