A room temperature surface acoustic wave hydrogen sensor with Pt coated ZnOnanorods

Abstract

A surface acoustic wave (SAW) sensor with Pt coated ZnO nanorods as the selective layerhas been investigated for hydrogen detection. The SAW sensor was fabricated based on a128°YX-LiNbO3 substrate with a operating frequency of 145 MHz. A dual delay line configuration wasadopted to eliminate external environmental fluctuations. The Pt coated ZnO nanorodswere chosen as a selective layer due to their high surface-to-volume ratio, large penetrationdepth, and fast charge diffusion rate. The ZnO nanorods were synthesized byan aqueous solution method and coated with the noble metal Pt as a catalyst.Finally, the SAW sensor responses to humidity and hydrogen were tested. Resultsshow that the sensor is not sensitive to humidity; moreover, the frequency shiftfor a hydrogen concentration variation of 6000 ppm is 26 kHz while operating atroom temperature. It can be concluded that the Pt coated ZnO nanorod basedSAW hydrogen sensor exhibits fast response, good sensitivity and short-termrepeatability. It is worth noting that not only is the sensor sensitive enough tooperate at room temperature, but also it can avoid the influence of humidity.