CMOS Gas Sensor Array Platform with Fourier Transform Based Impedance Spectroscopy

A digital readout CMOS interface platform for gas sensor array is demonstrated in 0.35 μm CMOS process. The chip contains 27 sensor pixels where each pixel can be functionalized with a distinct gas sensing material. A sensor pixel can amplify and digitize the sensor signal and perform impedance spectroscopy up to 10 KHz. Signal amplification is achieved by digitally programmable gain stages and digitization is done using continuous-time ΔΣ modulator. An on-chip reference pixel is provided to compensate for the phase shift introduced by the signal processing blocks. This chip is validated by functionalizing a sensor pixel with polycarbazole conducting polymer for sensing acetone The chip consumes 57 mW of power at 3.3 V supply.