Frequency behaviour of light-addressable potentiometric sensors

Carl Frederik Werner, Torsten Wagner, Tatsuo Yoshinobu, Michael Keusgen, Michael J. Schöning

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed.

Original languageEnglish
Pages (from-to)884-891
Number of pages8
JournalPhysica Status Solidi (A) Applications and Materials Science
Issue number5
Publication statusPublished - 2013 May


  • EIS
  • LAPS
  • frequency response
  • impedance
  • impedance spectroscopy
  • light-addressable potentiometric sensor


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