Superhydrophilic CuO nanowires QCM humidity sensors with horsefly-inspired self-cleaning ability applied on non-contact detection

Humidity sensor is crucial for broader applications like biomedicine and semiconductor fabrication. It is still a formidable challenge to achieve a humidity sensor with high sensitivity and anti-pollution ability. Inspired by horsefly eye, we propose a superhydrophilic CuO nanowires quartz crystal microbalance humidity sensor covered by micro-pit array, achieving outstanding self-cleaning properties. The physicochemical property of the sensing materials was characterized in situ by SEM, XRD, and XPS. The sensing characteristics of the specimen towards water molecules are studied by quartz crystal microbalance with dissipation monitoring, showing high sensitivity of 82.5±7.7 Hz/%RH. Molecular dynamic simulation and Brunauer-Emmett-Teller nitrogen sorption analysis are conducted for revealing the superhydrophilicity mechanism of CuO nanowires. Then a CuO nanowires humidity-sensing model is established, verified by both theoretical calculations and experiments. A smart non-contact sensing system based on the sensors was constructed, and the humidity intensity of human breath or fingers were detected. Our works demonstrate brilliant properties of the superhydrophilic CuO nanowires for non-contact sensing applications, providing new solutions for medical health monitoring, industrial environment detection, and human-computer interaction, etc.