A ZnO Humidity Sensor integrated with a-IGZO TFT based Preamplifier

In this work, a Zinc Oxide (ZnO) nanorods based humidity sensor integrated with an amorphous-Indium Gallium Zinc Oxide (a-IGZO) TFT-based preamplifier has been presented. The humidity sensor is modeled in a Wheatstone Bridge configuration with the ZnO nanorods grown onto one of its quadrants. Calibrated SPICE level-3 models are used for a-IGZO TFTs. The proposed TFT-based preamplifier uses a two-stage OPAMP topology with a high gain telescopic cascode structure and high output swing common source amplifier. The integrated sensor has successfully detected various humidity levels with a high dynamic voltage range (332 mV - 464 mV) and linearly increasing sensitivity due to high gain amplification (54.02 dB) of its output signal to discern signals for analysis and further conditioning.