成果報告書詳細
管理番号20150000000165
タイトル*平成26年度中間年報 水素利用技術研究開発事業 水素ステーション安全基盤整備に関する研究開発 水晶振動子を利用した信頼性向上が期待できる水素センサの研究開発
公開日2015/5/29
報告書年度2014 - 2015
委託先名学校法人早稲田大学 株式会社坂本電機製作所 コーア株式会社
プロジェクト番号P13002
部署名新エネルギー部
和文要約
英文要約Title : Research and Development of Highly-reliable Hydrogen Sensors using Quartz Resonator (FY2014-FY2015) FY2014 Annual Report

Theme (2): Sensitivity improvement and fabrication process establishment
Our sensors classified with a catalytic combustion hydrogen sensor that detects reaction heat of H2 and O2. A quartz resonator is used as a temperature detector. To increase reaction heat on the Pt catalyst, several methods have been adopted. However, our sensors have fine patterns and is fabricated by a wafer process using MEMS technologies, so adaptability to the wafer process has to be considered. Accordingly, we tested forming of a nano-Pt catalyst called platinum black using electroplating. As a result, we succeeded to control the film structures with sufficient patterning accuracy by changing current density. Pt films with metallic luster are deposited at the condition of lower current, and then it changed to platinum gray and black with current increment. In case of applying electroplating to MEMS devices; because total plating area is very small, it was possible to plate by less than 50 mA per each wafer which is especially less than industrial
electroplating.
Then, we tested electroplating on the actual wafer which is processed into 24 sensors using the dedicated developed jig. The result showed that it allow to selectively plate the Pt film on the predetermined electrodes
of all of the sensors.

Theme (3): Development of simulation technology
For shape optimization, thermal simulation is a useful method, and thermal analytical and diffusion theoretical methods have been established. However, these theories are difficult to apply to hydrogen sensor simulation because of dependency on the actual surface morphology of catalyst. Thus, from the experimental results of the prototype sensors, the reaction heat as a function of H2 concentration per unit catalyst area are estimated. Then, sensor characteristics which include sensitivity, time constant and power consumption were simulated. As a result of size optimization, time response allows to improve to less than 0.2 sec.

Theme (6): Development of sensor driving circuit
For systemization of the sensor, development of an oscillator circuit of quartz resonators, a heater controller and a digital calculation circuit are required. In this year, we began to consider the design of oscillator circuit. Firstly, typical oscillators which is a feedback circuit using logic IC were investigated. The sensors require stable oscillation until 100 MHz, but frequency range of the typical oscillator is less than 20 MHz. Additionally, one terminals of two resonators are connected each other, so it is difficult to apply typical oscillator to the sensor. Therefore, we determined to use a colpitts oscillator. As a result of the trial manufacture, stable oscillation was achieved on the commercial resonators (9-40 MHz) and the sensor (20 MHz).
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