Theoretical optimizations of acoustic wave gas sensors with high conductivity sensitivities

The frequency shift and electric loss induced by the variation of the surface conductivity caused by the sorbed matter in the acoustic wave (AW) gas sensor are evaluated with the transfer matrix method. It is found that the high conductivity sensitivity is always accompanied by the high electric loss, which increases the insert losses and the minimum detectable masses of the sensors. However, with the same electric perturbation, the AW sensors with longer operating wavelengths have smaller electric losses, which provides the opportunities to achieve the high conductivity sensitivity and reduce the minimum detectable mass simultaneously in the gas sensor.