SAW Gas Sensor with Nanostructured Sensing Materials

Abstract

Surface acoustic wave (SAW) sensors with nanostructured sensing materials for gas detection are reported in this paper. The SAW sensors were fabricated based on a 128Ŷ YX-LiNbO3 substrate with an operating frequency of 145 MHz. A dual delay line configuration was adopted to eliminate external environmental fluctuations. The camphor sulfonic acid doped polyaniline nanofibres and Pt coated ZnO nanorods were employed for the detections of humidity and hydrogen due to high surface-to-volume ratio, large penetration depth and fast charge diffusion rate. The nanostructured sensing materials were synthesized by the interfacial polymerization method. Finally, the SAW sensors were tested toward humidity and hydrogen. Results show our proposed SAW sensors exhibit fast response, good sensitivity and short-term repeatability while operating at room temperature