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

Ko ichiro Miyamoto, Kosuke Hayashi, Azuma Sakamoto, Carl Frederik Werner, Torsten Wagner, Michael J. Schöning, Tatsuo Yoshinobu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1006-1010
Number of pages5
JournalSensors and Actuators, B: Chemical
Publication statusPublished - 2017 Jan 1


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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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