Modeling of a piezoelectric fluid sensor excited by lateral fields using a spectral domain approach

Piezoelectric discs excited by lateral fields (LFE; both electrodes are placed on one side of the disc) show unique differences compared to common thickness field excited (TFE) resonators, in particular when they are used for liquid sensing. In this contribution the LFE-sensor setup is modeled as a layered structure in the spectral (wavenumbers) domain utilizing a semi-numerical approach. In particular the interaction of the piezo-disc and the sample liquid, which is too complex for analytical methods and too comprehensive for FEM, is efficiently modeled by the method. The calculation of frequency responses as well as electrical and mechanical fields are illustrated for a simulated setup. The simulation results are compared to results obtained from the Christoffel-Bechmann formalism, and sensitivities to fluid parameters like viscosity and conductivity are shown.