ZnO-nanowire-based extended-gate field-effect-transistor pH sensors prepared on glass substrate

The sensing membrane of a extended-gate field-effect-transistor (EGFET) pH sensor, consisting of a zinc oxide (ZnO) thin film and a ZnO nanowire array, was fabricated using the Vapor-liquid-solid method. The EGFET pH sensor with ZnO nanowire array exhibited significantly improved sensing performance owing to a large sensing surface-to-volume ratio. The measured current and voltage sensitivities of the pH sensor were 48.6 μA/pH and 36.9 mV/pH, respectively, at pH values ranging from 4 to 10.