Development of MOS Capacitor Dissolved Oxygen Sensor for Use in High-Temperature Solutions

Research Project

Project/Area Number	07555214
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	試験
Research Field	Material processing/treatments
Research Institution	TOHOKU UNIVERSITY
Principal Investigator	HARA Nobuyoshi Faculty of Engineering, Tohoku University Associate professor, 工学部, 助教授 (40111257)
Co-Investigator(Kenkyū-buntansha)	AKAO Noboru Faculty of Engineering, Tohoku University Research assistant, 工学部, 助手 (80222503) SUGIMOTO Katsuhisa Faculty of Engineering, Tohoku University Professor, 工学部, 教授 (80005397)
Project Period (FY)	1995 – 1996
Project Status	Completed (Fiscal Year 1996)
Budget Amount *help	¥7,400,000 (Direct Cost: ¥7,400,000) Fiscal Year 1996: ¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1995: ¥5,500,000 (Direct Cost: ¥5,500,000)
Keywords	Dissolved oxygen sensor / High temperature aqueous solution / MOS capacitor / EOS capacitor / Corrosion potential / 溶存酵素センサ / 貴金属
Research Abstract	New dissolved oxygen sensors based on metal-oxide-semiconductor (MOS) and electrolyte-oxide-semiconductor (EOS) devices have been developed for the measurement of oxygen concentration in high-temperature and high-pressure aqueous solutions. The results are summarized as follows ; 1. The system that can be served for the measurement of response characteristics of MOS and EOS capacitor sensors at elevated temperatures was designed and constructed. 2. Pt-PtO_x electrodes displayd a rapid response to changes in O_2 concentration and had a high resistance against corrosion at elevated temperatures. 3. The porous Pt-MOS capacitor sensor fabricated using a single crystal silicon as a semiconductor showed a linear relationship between the response voltage and log [DO concentration] at temperatures of 303-363K.However, this sensor suffered from cracking at temperatures above 423K. 4. The Pt-EOS sensor combining a bulk Pt electrode with a semiconductor electrode of TiO_2 single crystal displayd the same DO response characteristics as the Pt-MOS sensor, and had a good stability even at temperatures above 423K. 5. Calibration curves, which provide the relationships between the DO concentration and the response voltage of the Pt-EOS sensor, were obtained.