Humidity sensing properties of SrTiO3 nanospheres with high sensitivity and rapid response

Abstract

SrTiO₃ nanospheres were synthesized by a hydrothermal method and characterized by X-ray diffraction and scanning electron microscopy. Then, the material was coated on an Al₂O₃ ceramic substrate to fabricate humidity sensors using Ag–Pd interdigitated electrodes. The sensor shows high humidity sensitivity and fast response and recovery. The impedance changes by four orders of magnitude over a relative humidity (RH) range from 11% to 95%. At the frequency of 100 Hz, response and recovery times are both 2 s, and the maximum hysteresis is <1% RH. In addition, the complex impedance at different RH was investigated to understand the sensing mechanism. The results indicate potential applications of SrTiO₃ for fabricating high-performance humidity sensors.