Development of High Sensitivity Humidity Sensor Based on Gray TiO₂/SrTiO₃ Composite

A gray TiO₂/SrTiO₃ composite nanocrystalline sensor with narrow band-gap was successfully prepared through a facile wet chemical method. The precursor was calcined in N₂ flow under atmospheric pressure and thereafter, a humidity sensor based on the composite was fabricated. The sensor showed high resistive sensitivity and varied by more than four orders of magnitude with an increase in relative humidity (RH) from 11% to 95%. The response and recovery time were about 3.1 s and 76 s, respectively with maximum hysteresis at 1% RH. In comparison with pure SrTiO₃ and black TiO₂, the gray composite based device exhibits a higher sensitivity. These results demonstrate the potential of gray TiO₂/SrTiO₃ for humidity sensing applications.