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

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

Research output: Contribution to journalArticlepeer-review

6 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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