Synthesis of high response gold/titanium dioxide humidity sensor and its application in human respiration

Abstract

A high response humidity sensor based on Au nanoparticles (AuNPs) modified TiO2 (Au/TiO2) was designed for real-time monitoring of human respiration. Effects of Ti3+ defect content on the performance of TiO2 humidity sensor was further explored. Experiments show that AuNPs can make more Ti3+ defects to appear on TiO2 surface to enhance hydrophilicity of the materials, which can greatly enhance response of the humidity sensor. AuNPs can also increase oxygen vacancy and hydroxyl content on the surface of TiO2 to promote decomposition of water molecules into conductive ions and to accelerate the process of proton conduction. Such an Au/TiO2 humidity sensor shows high response (84366.9), good linearity, low hysteresis (4.76%) and high reliability in the range of RH from 11% to 95%. In addition, Au/TiO2 humidity sensor can effectively detect different breathing states and skin surface moisture, showing strong application potential in real-time respiratory monitoring and non-contact sensing. This research has further enriched factors that affect the performance of TiO2 humidity sensors, and also provides a possibility for the development of high-performance TiO2 respiration sensors.