Surface Acoustic Wave Humidity Sensors Based on Graphene Oxide Thin Films Deposited with the Surface Acoustic Wave Atomizer

Submicron-thick films of graphene oxide and polyvinyl alcohol (PVA) were deposited onto the surface of 160 MHz quartz surface acoustic wave (SAW) delay lines, and manufactured devices were used as humidity sensors. Films were obtained by consecutive atomization of 0.35 mu l droplets of 0.33 mg/ml graphene oxide water suspension or 5.00 mg/ml PVA water solution using 25 MHz SAW atomizers. During measurements authors did not observe additional attenuation of the surface acoustic wave propagating along the surface of the sensors, which confirms that deposited films have low thickness and good uniformity. It was shown that SAW quartz humidity sensors with graphene oxide films, PVA thin films and uncoated surface have sensitivity of 1.54 kHz/% RH, 0.47 kHz/% RH and 0.13 kHz/% RH respectively. Sensors with graphene oxide thin films showed the best sensitivity and dynamic response. It was concluded that they can be used as sensitive coatings in humidity sensors for industrial environment.