Method to quantify the effect of passivation layer in bio-impedance sensors

This paper investigates the effect of the passivation layer in a bio-impedance sensor. A sensor with 20 sensing sites has been designed, fabricated using a simple two mask process and tested. We have cultured in-vivo MDA-MB231 mammary cells and recorded the impedance from 1 kHz to 1 MHz. Processing the recorded data brings to light the drawback of the passivation layer which results in a drop in sensitivity of 13%. Simulation results based on parameters extracted from measurements re-affirm the drop in sensitivity. Thus, the passivation layer needs to be provided a special consideration in future design of the sensor as it can modify the response of the sensor.