Sensing Performance of EGFET pH Sensors with CuO Nanowires Fabricated on Glass Substrate

In this work, the sensing membrane of extended-gate field-effect-transistor (EGFET) pH sensors with an intrinsic copper oxide (CuO) nanowire array was fabricated on a glass substrate by directly heating a Cu film at 450°C for 5 h in air. It was found that the average length and average diameter of these nanowires (NWs) were 2.5 μm and 70 nm, respectively. The resulting EGFET pH sensors with CuO NWs exhibited significantly improved sensing performances owing to the large sensing surface-to-volume ratio. The pH sensitivity calculated from the linear relation between the drain-source current and the pH value was 23.5 μA/pH and that calculated from the linear relation between the reference voltage and the pH value was 18.4 mV/pH.