Fabrication of Highly Ordered Nanopillar Array Electrode for High-Performance Humidity Sensors

Humidity sensors are used in various applications to provide suitable environmental conditions. High-performance humidity sensors require highly sensitive active sites to detect water molecules. In this study, a nanopillar-array-based electrode (NAE) was developed, which has a large specific surface area and is applicable to various humidity-sensing materials. The NAE, which was fabricated via photo-lithography and soft lithography, exhibited superior electrochemical capacitance and diffusion behavior compared to flat electrodes. The NAE-based humidity sensor exhibited a high sensitivity and linearity, low hysteresis error, and long-term stability for a duration of 25 days. Moreover, the humidity sensor maintained a consistent impedance signal in a mechanically bent state. Furthermore, the real-time monitoring performance of the humidity sensor was demonstrated by measuring humidity changes during plant transpiration.