A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance

作者：Miyamoto Ko ichiro^*; Hayashi Kosuke; Sakamoto Azuma; Werner Carl Frederik; Wagner Torsten; Schoening Michael J; Yoshinobu Tatsuo

来源：Sensors and Actuators B: Chemical , 2017, 248: 1006-1010.

DOI：10.1016/j.snb.2017.03.002

• EIS capacitive sensor
• Chemical sensor
• Resonance-mode measurement
• Negative impedance convertor

An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change.

• 出版日期2017-9