Modeling of an LFE piezoelectric fluid sensor as layered structure in the spectral domain

Piezoelectric fluid sensors with an LFE electrode arrangement (LFE: lateral field excitation - both electrodes are placed on one side of the disc) show unique differences compared to common thickness field excited (TFE) resonators, due to the additional lateral field components produced. In this contribution the LFE sensor setup is modeled as a layered structure in the spectral domain utilizing a semi-numerical approach. In particular the interaction of the piezoelectric disc and the sample liquid, which is too complex for analytical methods or too comprehensive for FEM, is efficiently modeled by the method. The calculation of the frequency responses as well as the electrical and the mechanical fields are illustrated. The simulation results are compared to results obtained from the Christoffel-Bechmann formalism, and sensitivities to fluid parameters like viscosity, density, and conductivity are shown. Furthermore, the sensitivity to viscosity is compared to experimental data.