ZnO Nanorod-Based Humidity Sensors With Fast Response

Humidity sensors based on ZnO nanorods (NRs) have been developed using a Wheatstone bride (WB) configuration, where the ZnO NRs were selectively grown onto the one quadrant of the WB circuit. It turns out that the WB-based sensor possesses superior performances in terms of response and recovery time, and thermal stability in comparison with conventional types of resistive sensors. Thus, the WB sensor exhibits a fast response and recovery time (~1 s), and temperature-invariant behaviors over a broad range of temperatures up to 180 °C, which is likely because of the self-calibrating and error correction capabilities of the WB circuit itself.