Judul: Sensor Field Effect TransistorBerbasisNanoseratPolianilin untukMengukur Konsentrasi Gas Amonia
Abstrak: Gas sensors can be made of metal, metal oxide, organic conductive polymers. Gas sensors of organic conductive polymers have superiority such as showing good sensitivity to the vapors of organic compounds and can be used at room temperature. Polyaniline nanofiber as active layers of Field Effect Transistor (FET) sensor sensitive in responding to ammonia gas (NH3). This research consists of manufacturing and characterization of FET sensor and determine the sensitivity of the FET sensor. FET sensor is made by oxidizing silicon wafers (the type-p Si) as layer dielectric (SiO2) and coating polyaniline nanofiber on SiO2 layers. On the type-p Si layer isset with gate electrode while polyaniline nanofiber layer is set with drain and source. When the FET sensor is given with more negative gate voltage so that drain-source current increases. Sensitivity value of FET sensor at Vg = 0 V is obtained 3.4215 V/% and Vg = -5 V is obtained 3.9018 V/%. The sensitivity test results showsmore and more negative gate voltage is given to be the greater the greater sensitivity value.
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Judul: Pembuatan dan Karakterisasi Field Effect Transistor (FET) Berbasis Poly 3-Hexylthiophene (P3HT) untuk Mendeteksi Gas Amonia
Abstrak: Piranti FET berbasis P3HT telah dibuat dalam penelitian ini untuk dapat mendeteksi gas amonia. Lapisan silikon dioksida (SiO2) sebagai lapisan dielektrik pada piranti FET telah ditumbuhkan di permukaan atas substrat silikon dengan metode thermal, lalu substrat silikon dipanaskan menggunakan furnace pada suhu 1000oC selama 3 jam, kemudian gas oksigen (O2) dialirkan ke dalam furnace selama proses pemanasan berlangsung yang bertujuan agar gas oksigen berikatan dengan silikon sehingga membentuk lapisan SiO2. P3HT sebagai lapisan aktif pada piranti FET ditumbuhkan di permukaan atas lapisan SiO2 dengan metode spin coating. Hasil karakterisasi EDX menunjukkan bahwa dalam substrat silikon yang telah dioksidasi terdapat kandungan unsur O2 sekitar 35% dan unsur silikon sekitar 65%. Hasil pengujian karakterisasi I-V menunjukkan arus drain-source (Id-s) yang diperoleh dipengaruhi oleh perubahan tegangan gate (Vg). Semakin besar Vg yang diberikan maka Id-s yang dihasilkan semakin meningkat. Pengaruh gas amonia terhadap kurva karakteristik I-V menunjukkan bahwa Id-s yang dihasilkan semakin menurun seiring dengan penambahan konsentrasi gas amonia. Berdasarkan hasil respon dinamik piranti terhadap gas amonia memperlihatkan bahwa semakin besar Vg yang diberikan maka sensitivitas piranti semakin tinggi. Pada saat diberi Vg = -8 volt, setiap perubahan konsentrasi 1% maka akan terjadi kenaikkan tegangan sebesar 0,264 volt. Sedangkan ketika Vg = 0 volt, setiap perubahan konsentrasi sebesar 1% maka terjadi kenaikkan tegangan sebesar 0,236 volt.
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Judul: Revision of Rhynchoglossum (Gesneriaceae) in Malesia
Abstrak: Revision on Rhynchoglossum in Malesia has been done. This research conducted based on morphological characters of 233 sheets of Herbarium specimen and Herbarium specimen photographs from Herbarium Bogoriense (BO), Singapore Botanic Gardens (SING), National Herbarium Netherlands (L), Royal Botanic Garden Kew (K), Natural History Museum London (BM), Royal Botanic Garden Edinburgh (E), New York Botanical Gardens (NY), Smithsonian Institute (US), and Harvard University (A). The result shows that six species are recognized in Malesia and five are endemic. Five species are known previously namely R. borneense, R. klugioides, R. medusothrix, R. obliquum, and R. spumosum; one species is proposed as a new and newly described namely R. celebicum. Rhynchoglossum borneense and R. medusothrix endemic to Borneo, R. celebicum endemic to Sulawesi, while R. spumosum endemic to Philippine Islands. Rhynchoglossum klugioides and R. obliquum distributed wider in Malesia. Rhynchoglossum papuae and R. merrilliae are placed under synonym of R. obliquum and R. spumosum. A phylogenetic analysis using PAUP version 4.0 program based on 60 morphological characters with Stauranthera coerulea and Loxonia hirsuta as an outgroup was undertaken. The analysis resulted a parsimonious tree which shown that Rhynchoglossum in Malesia can be divided in two groups. First clade consist R. obliquum, R. spumosum and R. celebicum while the second clade consist R. klugioides, R. borneense and R. medusothrix. Taxonomic treatment was giving with a identification key to the species, description, nomenclature, distribution, and notes each species.
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