Proposal, Design, and Performance Investigation of ZnO-Based ISFET pH Sensor

This study investigates pH sensing using an ion sensitive field effect transistor (ISFET) built from the nanomaterial zinc oxide (ZnO) and using a thin film transistor (TFT) design. The device shows an excellent Ion/Ioff ratio > 106 for low-power applications with high transconductance (gm = 0.342 mS/µm), representing the available surface area for detecting hydrogen ions (H+). The device has a variety of figures of merit (FoMs), including average sensitivity (current & voltage) and signal-to-noise ratio (SNR). One type of sensing metric is the variation in threshold voltage. The impact of pH on different parameters (potential, drain current, transconductance) is analyzed. The simulated device’s sensitivity response is near the Nernestian limit of 59 mV/pH. The planned device shows good stability and sensitivity for sensing pH values during simulation.