This bridge
girder is tilted,
isn't it?

Today,traffic isheavier thanusual.

Oh, a truck justpassed that’s
too heavy forthe bridge!

Solutions for today’s challenges

Sensors
Answering
the Call!

01

METI Journal │ がんばる、センサーT

he Tokyo Gate Bridge is nicknamed the “Dinosaur
Bridge” because of its unique shape. If you lookat the bridge, you may find that it looks like twodinosaurs facing each other.
Not only is its shape unique. Did you know that the giant
bridge has a fine nerve network? In fact, this nerve network
is attracting attention as a step towards solving various
social issues facing Japan at present.
The nerve network is a “sensor-based monitoring system.”
Various sensors are installed below the roadway surface at
the center of the bridge to check the structural soundnessof the entire bridge by measuring displacements, vibrations,tilts and other small changes.
This fiscal year, the Ministry of Economy, Trade andIndustry (METI) launched a “Project to Develop Sensor
Systems for Responding to Social Issues.” The project
aims to “research and develop energy saving microsensors
and control systems.” The goal is to solve social issues

plaguing (1) social and public infrastructure, (2) agriculture,(3) healthcare, and other areas.
Specifically, these sensor systems may be used for thefollowing sorts of applications:(1) Discovering anomalies and damage to bridges, roads,
buildings and other structures to “manage infrastructure”(2) Monitoring agricultural conditions including temperatureand humidity to “appropriately control agricultural
products,” and(3) Measuring blood pressure, blood glucose and otherbiological indicators to “detect the three major diseases(and others) at an early stage and prevent these diseases
from worsening.” The monitoring system for the Tokyo Gate
Bridge represents one of these applications.
Why are sensors required for such purposes? What kindsof sensors are required? What are present sensors like? Wehave tried to explore the overall picture of the project froma variety of perspectives.

METI Journal

02

Visualization Can Make a Difference in Social andPublic Infrastructure MaintenanceTokyo City University Professor Chitoshi Miki describes the development of a bridge monitoring system as“the installation of a nerve network and a brain on a bridge.” Prof. Miki has long been engaged in researchon infrastructure design and maintenance. We interviewed Prof. Miki on the present status, directions andchallenges of sensor systems.

T

he deterioration of social and public infrastructure,

Prof. Miki has investigated fatigue in bridges since the 1980s.

including bridges, tunnels and roads that

He has also engaged in research on the maintenance of

support social activities, has recently become

bridges for Shinkansen railways, metropolitan expressways

a problem. This is because Japan’s social andand major national roads in that time. About 10 years

public infrastructure development was concentrated in theago, Prof. Miki launched a study on how to use sensor

high economic growth period of the 1960s and 1970s. “Thetechnologies to check for structural deterioration. He

massive concentration of development over such a limited

developed an optical fiber sensor monitoring system which isperiod is unique in the world,” said Prof. Miki. Data fromattached to the opening of the lower deck (Route 357) of thethe Ministry of Land, Infrastructure, Transport and Tourism

Yokohama Bay Bridge.

indicate that about 40% of road bridges and tunnels in Japan“Attempts have been made over a long time to use sensors

will become more than 50 years old in the next decade.

to check the condition of structures. But previous attempts

Shifting from Movement Observation to“Preventive Maintenance”

focused on movement observation to check whether bridges“At present, the designed service life of bridges is globally
set at around 100 years. Appropriate maintenance canprovide bridges to continue working for such a long time. But
structures built in the 1960s have begun to gradually develop
damage due partly to later dramatic increases in traffic.
Effects of earthquakes are also a major issue. How to secure
the same level of ‘safety’ and ‘security’ for all social and public
infrastructure is the challenge we face now.”fiber sensor technology and a new concept of “preventive

The “bridge monitoring system” of the Tokyo Gate Bridge uses fiber optic sensors.
The system measures displacements and vibrations by sensing changes in
the reflection of incident light. It will contribute to early detection of continuous
deterioration and damage by continuing to monitor such changes over a long
period of normal operation, and of course, during earthquakes and other disasters.
Given that optical fibers are cables whose installation poses labor and costchallenges, efforts are under way to develop wireless monitoring systems.

▶ Measuring deformation

Optical fibers
send data▶ Monitoring throughmeasuring heavy vehicles▶ Bridge anomaly detection system

OK!

Information Center

OK!

OK!
OK!

▶ Vehicle detection system

OK!

???

In parallel with the construction of the Tokyo Gate Bridge,
various sensors, including deformation, acceleration anddisplacement meters were developed and installed, according
to a “bridge deterioration scenario.”
The scenario includes estimates of degrees of damage
caused by strong earthquakes, which have been projectedwith the latest analysis techniques. A wide range of expertiseof preventative maintenance systems. The know-how is used
for determining “what and how many sensors should beinstalled where, and to collect what data.”
Massive amounts of data on displacements, vibrations, tilts
and other changes are sent and received in real time. An
information center collects and analyzes this data. Prof. Miki
explained: “Sensors work as the nerve system and computers
as the brain. They are connected through sophisticatedinformation and communications technology. Thanks to theevolution of these three technologies, the present monitoring
system is possible. But there are still multiple problems for the
future.”METI Journal │ がんばる、センサー▶ Measuring acceleration

maintenance” to manage the integrity of bridges,” he said.

maintenance and conservation is required in the development

03▶ Measuring displacement

work as designed. We have come up with a new opticaland know-how in the structural design as well as inChitoshi Miki, Vice President of Tokyo City University and Professor at its Advanced
Research Laboratories. Born in Tokushima Prefecture in 1947, he graduatedfrom the Tokyo Institute of Technology Graduate School in 1972. He assumed his
present post in 2012 after serving as assistant at the Tokyo Institute of Technology,
associate professor at the University of Tokyo, dean and professor and vicepresident of the Tokyo Institute of Technology. He also chairs the Road Maintenance
Subcommittee of the Social and Public Infrastructure Development Council at the
Ministry of Land, Infrastructure, Transport and Tourism.

Tokyo Gate Bridge
Monitoring System

Discussions on “Cost-Benefit Ratios” areIndispensable

Prof. Miki said: “The battery life is reported to be around one

maintenance research and development,” said Prof. Miki.

year. But regular inspection work on a bridge is conducted“If a road bridge on the metropolitan expressway system isonly every five years. Battery life may have to be extended toreplaced, societal losses including losses associated withat least this level.”traffic closures may far exceed 100 billion yen.” In fact, there is

The METI project aims to develop “energy saving (independentan abundance of ageing infrastructure in need of replacement

electricity source, wireless communication and maintenance-

in Japan. Societal losses from the aging of bridges and roadsfree)” microsensors. Given that sensors may be installed atare far more costly than we assume.

locations that are difficult for humans to check, independent“We must also consider creating new business models.

power sources which convert heat and light energy into

Historically, priority in construction technology has tended

electricity are indispensable.

to be given to new infrastructure development rather thanAnother key point is the price of sensors. Prof. Miki said:

maintenance. Unless we cooperate with the business“Building a monitoring system constructed with current

community to develop mechanisms to secure returns on

optical fiber sensors costs around 10 million yen. The costinvestment in maintenance, it may be difficult for private sector

is unrealistic for nationwide bridge maintenance. At present,

enterprises to enter the infrastructure maintenance business.”

MEMS (microelectromechanical systems) technologies are

There are many challenges to be solved before establishingmaking sensors cheaper. With performance and cost taken

new sensor systems. METI plans to begin the project byinto account, research in this field will be critical in the future.”

determining these “problems” and “on-site needs” andOne more important point is that the largest challenge is thecooperate with sensor users in demonstration research.

“cost-benefit viewpoint.”“I hope that I will someday hear that Japan’s infrastructure has“How much should be spent on social and public

been successfully restored thanks to sensors.’’’infrastructure maintenance and management? Who would

The potential of sensors will continue to increase.

One of the challenges cited by Prof. Miki is the performance ofshoulder the cost? It is important for all stakeholders tosensors. The performance includes the battery life of sensors.

discuss and share in the costs including investment in

CLICK!

● Tokyo Gate Bridge ● Tokyo City University

METI Journal04

Investigating Simple Questions Thoroughly!

Team Member No. 1

Sensors are everywhere in everyday life, although we are seldom conscious of them.

Sensor Exploration Team

What are these reliable sensors? What functions do they have, and where are they?
We interviewed two experts on everything from fundamentals to future potential!
Team Member No. 2

Sensors are everywhere in everyday life.
Toward a Society Protected by Sensors
No. 1: Automobiles, airconditioners, digital cameras,
smartphones… Sensors are usedin many different devices.
No. 2: What roles dosensors play?
Fujimaki: A kettle tells us
water is boiling by whistling.
A doorbell informs us of a visitor.
Although sensors are thought of as
devices sending radio signals, there
are also other kinds of sensors. In
brief, sensors sense something for

Sensors visualize what
humans cannot see
Dr. Makoto Fujimaki

us, inform us, or tell machines to
do something on our behalf. That’s
what sensors are!
No. 1: I see! Sensors
represent an extension ofhuman senses.
Fujimaki: Yes. The word
“sensor” originates fromthe word “sensing.” Sensors aredevices that visualize and moreaccurately detect what humans
cannot see. We are actually usuallyin the presence of various kinds ofsensors. Sensors are in fact alreadywidespread and have the potential
to contribute to solving various
social issues.
No. 2: What sort ofconvenient sensors can we
expect to see in the future?

← Planning Officer, Research
Planning Office for Information
Technology and Electronics, National
Institute of Advanced Industrial
Science and Technology. As a Doctor ofEngineering, he has been engaged indeveloping sensors since 2004.

05

Fujimaki: I am
researchingbiosensors to detect
proteins in the body.
As you probably know,

Sensors Chatting with Each Other!?
lifestyle-related diseases havebecome a major problem. Whilediseases develop without being
detected by humans, it is widely
known that some small changes
are seen in the initial phases ofthe development of a disease. So,
more sensitive sensors may beable to detect such small changes
and prevent the development ofsuch diseases. At present, blood
samples are taken by sensors tomonitor body data. In the future,sensors may be developed whichenable diagnosis without invasive
blood samples being taken.
No. 2: Sensors will also be
useful to maintain a healthy
life!
Fujimaki: We areapproaching a world where
humans will be passively andnaturally protected by sensors.
CLICK!

● National Institute of Advanced

Industrial Science and Technology

No. 1: What do you think
are the key words for futuresensor development?
No. 2: I’ve heard about theword “miniaturization.”
Imanaka: Yes. That is oneof the key points. First, let’s
review how sensors have advanced.
Some sensors can decide whether
specific data are necessary or not.
These sensors that discriminate
necessary data from other data
are called “smart sensors.” Ultrasmart sensors with advanced data
discrimination functionality can chatwith each other.
No. 1. Oh! What do you
mean?
Imanaka: For example, one
cleaning robot can handle
cleaning a small room. In a large
space, however, multiple robots
can be used to increase efficiency.
Then, sensors send and receive
messages between the robots,
informing them “this part has beencleaned.” In this way, sensors canto enable continuous monitoring.
work collaboratively with chatting
No. 1: Prices may have to beeach other.
lowered to allow for a large
No. 2: Sensors arenumber of sensors to be used.
cooperating with each other
Imanaka: Yes. I would likevery well! Is this related to theto realize such systems as
sensor network system you are
early as possible. I’m confident
currently researching?
that sensors have the potential to
Imanaka: Our NMEMS
enable a more secure, safe andTechnology Researchefficient society.
Organization has beendeveloping a system that reduces
CLICK! ●NMEMS Technology Research
Organizationenergy consumption in society
using compact and low-cost
sensors with energy harvesting andwireless communications functions.
This technology may be used for a
Sensors have the potential
wide range of areas including public
to change society
infrastructure, factories and officebuildings. Of course a single sensor
may break down or lose power,
Dr. Koichi Imanaka
so it is important
to install multiple→ Chairman of NMEMS Technology Researchsensors with energy
Organization and Doctor of Engineering. Before
harvesting functions
taking up the current post in 2011, he was engaged
in developing sensing devices at Omron Corp.

▶ Air conditioners▶ Cars▶ Smartphones▶ Lighting▶ Integrated Circuit Cards

Recent air conditioners are equipped with not
only temperature sensors but also infrared
sensors that can detect the presence or absenceof humans. They control heating and coolingdepending on room conditions.

Check engine revolutions, measure distancesfrom other vehicles and control braking. Sensors
are installed at various locations to support asafe car-based life.

Smartphones indicate walking directions andprovide games that can be played by tilting thehandset. They are also mounted with acceleration
sensors to provide a wide variety of functions.

An infrared sensor senses human movements
and automatically controls lighting. Sensors areuseful for not only energy conservation but also
for security. Automatic doors also depend on
sensors.

Various integrated circuit cards support smooth
movement of passengers using trains and buses.
Sensor technology works to send and receive
data stored on cards with data readers.

METI Journal │ がんばる、センサーfor Transportation▶ Digital Cameras
Sensors are indispensable for digital cameras tomeasure light levels. Digital camera autofocus
devices are also a type of sensor.

METI Journal

06

Attempts Have Already Been Made to Use

Sensors to Conserve Electricity!
Sensors Visualize Work Conditions!

Promoting Energy Saving in Small andMedium-Sized Buildings!

Seven-Eleven Japan Co., Ltd.

Daikin Industries, Ltd.

cleaned. These failures made a greater
contribution to electricity consumption
than expected. When inspectors
visited stores that used more power
consumption for air conditioners,
they found that these stores left
entrances open to allow for frequentcustomer visits. These findings meantthat sensors visualized electricity
consumption as well as each store’s
business situation.
In response to the results of thedemonstration test that Seven-Elevenconducted jointly with AIST and
NEC, the convenience store chain
implemented thorough utilization of thepower save mode for fryers, stricter

lighting controls, modified operation
manuals for refrigerators etc., andhas successfully and substantiallyreduced electricity consumption. The
achievement has been shared with
Seven-Eleven stores throughout Japanto encourage their electricity saving.
The convenience store chain is
now further improving its energy
consumption efficiency by installing
environmental sensors to measuretemperature, humidity and atmosphericpressure levels in addition to electricity
sensors. Miniature sensors encouraged
innovation in the company.

CLICK!

● Seven-Eleven Japan Co., Ltd.

A further 10% energy saving
by using a “bird’s-eye view”
of rooms
In this demonstration test, Daikin
has newly developed an infrared
array sensor to monitor not only thetemperature, but also the location ofoccupants. Since a tiny PV panel was
integrated with the wireless sensor,
wiring installation for power supply andcommunication were eliminated. The
sensor is very small; the size is at only 2
cm x 5 cm.
With multiple sensors, the entire room

Notifying building
operators of energy loss
locations and relevant
responses throughemail or Twitter

1

Data acquisition andtransmission

d

se

rv

er

Sensors
attached to theceilinguStore
staff member

Building occupants

d
ze
aly
An ata sion
d is
m
ns
tra

NRI, NEC, etc.

7

En
ELEV

Displaying energy
loss locations in realtime

Small or mediumsized building

ta ionDa issmns
tra

A Seven-Elevenstore

Distribution
board

Data receiving andanalyzing

ck
ba
ed
Fe

sensor2

Data reception andanalysis2

lo

Sensors are installed at wiring
for fryers, air conditioners andother machines.

M

d
ze
aly
An ata sion
d is
m
ns
tra

METI Journal │ がんばる、センサー

Seven-Eleven
Head Office

ck
ba
ed
Fe

When the thumb-sized, easy-to-installsensors were installed on distribution
boards to measure the electricity
consumption of in-store lighting, airconditioners, fryers for fried food andthe like, various findings were made.
For example, the power save modesof fryers were not being used. Filters
for air conditioners were not being

Data collection andtransmission

ta ionDa issmns
traDemonstration Test Results
Led to Substantial Electricity
Conservation

1

any small and medium-sizedbuildings have failed to makeprogress in saving energy.
One factor behind thefailure is that these buildings differ fromlarger buildings subjected to stricter
legal regulations and lack operatorswith expertise. Operators of small andmedium-sized buildings also fail to
identify the sources of energy loss orpromptly devise improvements. These
actions are difficult to be taken for suchbuildings.
Daikin Industries, Ltd. wants to provide
tools and offer services that overcome
such weak points of small and mediumsized buildings. Daikin, whose main
business is air conditioning equipment
manufacturing, is striving to establish
an energy management system that iseasy to operate, affordable and easy
to install. Daikin has teamed up withsensor suppliers (Omron Corporation,
Rohm Co., Ltd., Hitachi Ltd., and NTT
Data Corporation) to form a task force
with the following concept; “to visualize
energy losses in real time by onlyattaching sensor terminals to ceilings”
and “propose countermeasures topromote energy saving.”CS

even-Eleven Japan Co.
has more than 15,000
convenience stores acrossJapan and has been
increasing the number of stores every
year. The largest convenience store
chain in Japan is socially responsible for
reducing carbon dioxide emissions andconserving electricity. CO2 emission
reduction and electricity conservation
are great business goals. In fact, theentire chain’s CO2 emissions annuallyreach 1 million tons and its annual
electricity charges totaled about 34.4
billion yen in 2010. Taking necessary
measures to address this situation wererequired.
The measures Seven-Eleven Japan
had implemented to this end included
the adoption of commercially available
ammeters to determine the amountof electricity consumption at thestores. Upon discovering that anammeter costs as much as 400,000
yen, however, the company began
searching for more economical
methods. In 2010, it found a small
wireless electricity sensor under joint
research and development by the
National Institute of Advanced Industrial
Science and Technology (AIST) and
NEC Corporation.

07

Energy saving and cost reduction are challenges that any enterprise must deal with constantly.
The emergence of sensors has led to a rise in new ideas for solutions.
We would like to introduce two enterprises that have made positive efforts to that end.

sensorcan be overlooked. For instance,
optimum air conditioning can becontrolled, because the monitor
displays the number of occupantsin the room as well as the locations
from which the areas do not need air
conditioning and ventilation can be
determined at a glance. Based on thereal time data measured at other officebuildings, we estimated the effectof energy saving by introducing thissystem, and obtained data that shows
an approximately 10% reduction ofenergy consumption can be expected,
even in buildings that have alreadytaken energy saving measures.
Daikin is expected to take further steps

to commercialize sensor systems thatcan not only measure data but also
“process data into a meaningful form.”

CLICK!

● Daikin Industries, Ltd.

METI Journal

08

A New Future Guided by Sensors│担当者の声How will our life change with the advancement of sensors?
Let’s look at some of the changes!

Electricity consumption
and dust levels in clean
rooms, stores, offices
and other facilities will
be analyzed to realize
optimum energy control.

Sensors installed on bridges androads will detect anomalies causedby damage and natural disasters andcontribute to accident prevention.

Controlling
infrastructure“health”「シーズ」主導の開発から「ニーズ」起点の課題解決へ
瀬戸 幸

産業技術環境局 研究開発課

ーと橋梁構造との関係など非常に興味深かった」と話します。道路や橋

瀬戸 2008 年度に「BEANS（異分てニーズを中心に検証していく計画

野融合型次世代デバイス）プロジェ
クト」（08 年～ 12 年度）で革新的デバイスの研究に着手。これはMEMS

CLICK! ●Outline of the Sensor System Development

Projects Responding to Social Issues(cited from NEDO’s information on invitation
for applications)です。

──センサーとは社会のなかでどんな存在なのでしょう？

瀬戸 社会の安心・安全を見守る上「社会課題対応センサーシステム開ジでしょうか。例えば道路や橋梁をき継ぐ形で、11 年度から「グリーン

クルマで走るとき、誰も見守られてセンサー統合制御システム実証プロ

いるとは気づかないけど、さまざま

ジェクト」（11 ～ 16 年度）がスター

なセンサー群が、ひずみなどの変化

ト。
「グリーンセンサー」の主な狙いを常時センシングし、社会インフラ

は、「省エネ」と CO2 排出量の「見の維持管理、長寿命化に役立っていえる化」です。ビルや店舗など、実る。センサーは情報入力系であり、ポイントはどこでしょうか。

瀬戸 特徴は、2 つあると思います。 際にセンサーが活用されている事例

での“縁の下の力持ち”的なイメー

その検出データを蓄積し解析・評価

1 つは「社会課題」というニーズをを見るとき、やはり MEMS 技術にするシステムと、一体不可分で働く

起点に実用化を進めている点。もうよる超小型化がポイントだと思いまもの。その力をより発揮できる技術

1 つは「小さな投資で大きな課題にす。小さいと量産化しやすく、低コの開発に向けて、実証実験を進めて挑む」という、本事業の基本姿勢でスト化や省電力化にもつながる。セ

いきたいと思います。

す。これまでの研究開発は“技術シンサーシステムの実用化には必須のーズ主導”が多かった。しかし今回条件ですね。

はまず“課題をどうするか？ ”というニーズがあり、そこから必要な仕様を整えていく、というやり方をとcould generate greater effects by being connected with
manufacturing. Sensors have the potential to “improve
Japan’s international competitiveness.”を整えていく予定です。
In order to accelerate such efforts to develop sensors,
METI is promoting “Sensor System Development Projects
Responding to Social Issues.” Under the projects, METI will
provide subsidies while considering feeding back the research
results so that they could be adopted to the reform of relevant
institutions and regulations, and also plans to developarrangements to support private enterprises.

うセンサーの基本要件を含め、改めたプロセス技術などの要素技術を引――このプロジェクトの特徴や注目

METI Journal │ がんばる、センサー

線通信」「メンテナンスフリー」といに主眼がありました。そこで確立し今後の方向性などを聞きました。

09――超小型センサーの開発自体は早「農業」「健康医療」分野の課題解決

発プロジェクト」。その狙いや特徴、

Temperature, water levels and other environmental
information, electricity consumption, chemical substances,
etc. Sensors have a massive range of potential uses and thescope for sensors is continuing to expand. If ongoing research
efforts by various enterprises and organizations successfully
improve the sensitivity of sensors and further miniaturize them,solutions that have been historically viewed as excessively
difficult will grow more realistic.
As shown above, new devices will be manufactured tosupport human health promotion in the future. Higherquality farm products will be produced more efficiently.
Sensor technology will make our lives more affluent and推進しています。

係員

技術の活用
梁などの「社会インフラ」のほか、 （微小電気機械システム）

Sensor-collected data will be used
to make plant factory production andlivestock raising more efficient.

来開拓研究」などのプロジェクトをくから進められていましたね。

へ向け、先導的な調査・研究が進む

A sensor attached to ahuman body will monitor
daily health conditions
and detect even small
signs of variation.

間企業に繋いで実用化を進める「未うのは産業技術環境局研究開発課の専攻しており「げた下にあるセンサ

Sensors
playing greaterroles inagriculture andlivestock

業や雇用を生み出していくため、大学・研究機関などの新しい技術を民「無の連携・協調が増えてくるはずです。 来から目指している「自立電源」

瀬戸幸さん。学生時代は土木工学を

No smallchanges need
be overlookedなどの課題を克服しつつ、将来の産「東京ゲートブリッジでは橋げたにある点検通路にも入りました」と言

Wiser
energyconsumption

当課は、我が国がエネルギーや健康っています。
そのなかで、関係省庁や機関・団体との連携をさらに強化。限られた予算を有効活用するべく、民間企業

安心・安全を見守る“ 縁の下の力持ち”――対象として 3 分野が取り上げられています。

瀬戸 今回の事業では「グリーンセンサー」の技術成果を受けつつ、フにも広く事業参加を呼びかけていまィジビリティスタディ ( 実行可能性

す。すでに産業技術全体の育成につ

調査 ) から着実に進めていく方針で

いては、数年前から基礎研究を所管す。
「社会インフラ」「農業」「健康医

する文部科学省と融合的に政策が進療」分野が抱える課題とマッチング

行中で、今回のプロジェクトでも今させた方向で、まずは“どんなセン

後、国土交通省や厚生労働省などとサーが有効なのか”を探ります。従METI Journal

10