Skip to Main Content
Layered surface acoustic wave (SAW) devices for the detection of ethanol in dry and humid air were fabricated on 36° YX LiTaO3 utilizing a 1.2 μm zinc oxide (ZnO) intermediate layer. A 150 nm tungsten trioxide (WO3) sensing layer was deposited via r.f. sputtering. Sensor performance was analyzed in terms of response magnitude as a function of operational temperature. Different relative humidity (RH) levels for various ethanol concentrations were investigated. Frequency shifts of 119 kHz, 90 kHz and 86 kHz towards 500 ppm of ethanol in air were observed for 0%, 25% and 50% RH, measured at 20 °C, respectively. The effect of elevated temperatures on the sensors' surface morphology is presented. The influence of humidity on sensitivity is investigated at different operating temperatures. At the highest sensor operating temperature of 300 °C, the largest response was observed.