The response mechanism of surface acoustic wave gas sensors in real time

A simulation model to describe the real-time response mechanism of the surface acoustic wave (SAW) gas sensors was established. This model was based on the perturbation theory, the Langmuir formula and the fundamental transport equations. Perturbation theory was utilized to describe the relationship between the sensor’s output and the mass loading on the detector’s surface. The Langmuir formula and fundamental transport equations were quoted to depict the adsorption–desorption behavior of gas on the sensitive film. According to these theories, the mass loading curve was obtained by using the finite element method with COMSOL. By configuring a SAW gas sensor coated with zinc oxide quantum dots, an experiment was performed to measure the frequency shifts caused by adsorbing and desorbing dimethyl methyl phosphonate. Excellent repeatability was observed in gas sensing experiments. The simulation curve is consistent with the experimental results.