Sodium Titanate Nanorod Moisture Sensor and Its Sensing Mechanism

Sodium titanate Na₂Ti₆O₁₃ nanorods were synthesized by a hydrothermal method and characterized by X-ray diffraction and scanning electron microscopy. Then, the material was coated on a Al₂O₃ ceramic substrate to fabricate humidity sensors using Ag-Pd as interdigitated electrodes. The sensor shows high humidity sensitivity and fast response and recovery. The impedance changes by five 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 <;3% RH. In addition, the complex impedance at different RH was investigated to understand the sensing mechanism. The results indicate potential applications of sodium titanate for fabricating high-performance humidity sensors.