Kinetic characteristics of the SAW humidity sensor partially coated with graphene oxide thin film

Atomization of one or two microliter droplets of aqueous dispersion of graphene oxide (GO) by the surface acoustic wave (SAW) atomizer was used to deposit GO sensitive films of 15–30-nm thickness onto the surface of the SAW humidity sensor. Sensitivity of the sensors with these films as sensitive elements was calibrated over a wide range of humidity using a special procedure of preparation of standards, and adsorption kinetic curves for this process were obtained. The first-order rate kinetic equation with special additional linear term was shown to be adequate for modeling the kinetics of water adsorption onto the GO thin film. All parameters of this equation were calculated from least-squares fitting of experimental data. It was shown that the sensor partially coated with the graphene oxide film has good sensitivity and very short response time. The developed approach of experimental data treatment can be used for calibration of various types of portable SAW sensors.