Modelling of an electroacoustic gas sensor

A theoretical model of an electroacoustic gas sensor has been designed and compared with experimental data. The sensor includes a piezoelectric element coupled to an acoustic resonator depending on the average molecular weight of the gas with respect to resonance frequency. The model is based on a transmission line coupled to a Butterworth van Dyke model of the piezoelectric element. The frequency characteristics of the sensor impedance was both simulated and measured on prototype sensors. The results indicate that the model provides an adequate description of overall sensor behaviour, and will constitute a useful design tool. Due to interdependencies of the model parameters, the precise quantification of sensor characteristics will either require highly accurate parameter data, or a considerably more complex model.