Improvement on pH-Sensing Device Constructed of IrO2 and Ta2O5 Films

• Main Authors: Chao-Ting Chen, 陳昭廷
• Other Authors: Shu-Chi Chao
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/25544141179877598004

碩士 === 國立交通大學 === 電子物理系所 === 96 === ISFET, Ion Sensitive Field Effect Transistor, was first proposed by Piet Bergveld in 1970 to have ion sensitivity and field-effect transistor components of micro-chemical sensors. The ISFET is in accordance with the process technology, MOSFET, and can be mass-produced. Using the RF magnetron sputtering method, iridium oxide is electroplated onto the platinum electrode as a hydrogen ion sensors film. Then a thin layer of tantalum oxide film is sputtered on the electrode as an ion-selective membrane that coats the iridium oxide. This will produce a hydrogen ion sensing electrode that is selective toward hydrogen ions with linear work areas that are in between pH2 and pH12, and a sensitivity of 56.03 mV / pH. The hydrogen ion sensing electrode has advantages of good stability and reproducibility, and an average response time of 20 seconds to changes in the pH of the solution. It is resistant to acid corrosion, and has a lifetime that is at least four months.