Characterization of CMOS electrochemical oxygen sensor for biomedicai applications

This paper presents the characterization procedures of a CMOS electrochemical oxygen sensor and its readout circuits in application specific integrated circuit (ASIC) format. As the sensor needs to be tested inside deionized water, a master controller Printed Circuit Board (PCB) is designed to provide power and control signals to test the ASIC. The transimpedance (TIA) amplifier gain, voltage amplifier gain, sensor array sensitivity and 8-bit Digital-to-Analog Converter (DAC) trimming voltage are configured through the master controller. The oxygen sensor ASIC is mounted on another PCB with chip-on-board (COB) packaging. Biocompatible hydrogel Nafion is coated to cover the entire sensor electrodes for oxygen transportation. The measured sensor sensitivity is 0.78 mV/mmHg and a transient output voltage change of 50 mV is observed when the deionized water is changed from air saturation to nitrogen saturation.