Analysis of the passivation layer by testing and modeling a cell impedance micro-sensor

Shree Narayanan, Mehdi Nikkhah, Jeannine S. Strob, Masoud Agah

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


This paper describes the fabrication and experimental results of a microchip for cell impedance spectroscopy. A model with parameters extracted from the measurement is used to investigate the influence of the passivation layer on the impedance measurement sensitivity. The 2mm square chip fabricated with a simple two-mask process contains a sensor with a 1mm square sensing window with 20 sensing micropatterned electrodes. The chip successfully monitored the growth of MDA-MB-231 human breast cancer cells and recorded the impedance from 1 kHz to 1MHz and demonstrated a peak frequency of about 100 kHz in the impedance spectrum. Thorough analysis of the result revealed that the passivation layer, which is typically used to reduce the sensing window size, results in a drop in sensitivity of 13%. This observation is consistent with the simulation results based on parameters extracted from measurements. Thus, the passivation layer needs to be provided special consideration in future designs of the sensor as it can modify the response of the sensor, in order to alleviate its detrimental effect.

Original languageEnglish (US)
Pages (from-to)241-247
Number of pages7
JournalSensors and Actuators, A: Physical
Issue number2
StatePublished - May 2010
Externally publishedYes


  • Bio sensor Cell impedance Passivation layer Modeling Breast cancer

ASJC Scopus subject areas

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


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