Surface acoustic wave sensor with CuO layer and its detection for ammonia

In this study, copper oxide (CuO) was successfully synthesized using the hydrothermal method under controlled conditions of 180 °C for 24 hours with various concentrations. CuO thin films were deposited onto the acoustic wave propagation region of surface acoustic wave (SAW) devices via spray pyrolysis. The performance of the devices in ammonia gas sensing was investigated. Under environmental conditions of 25 °C and 50% relative humidity, ammonia gas sensing was evaluated with different concentrations, and the frequency characteristics of the SAW devices were measured using a network analyzer. Experimental results revealed that the frequency response of the SAW devices exhibited a linear change with increasing ammonia concentration. The crystal structure of the CuO films was confirmed through X-ray diffractometer (XRD) analysis, while surface morphology variations were observed using scanning electron microscopy (SEM). The sensors demonstrated potential for specific gas sensing applications while the device achieved a sensitivity of 220 Hz/ppm for ammonia gas.