Acoustoelectric effect in piezocomposite sensors

The acoustoelectric effect, given by conductive liquid loading, on the first symmetric mode of Lamb wave in piezoelectric composites was theoretically investigated. This S0 mode shows a low phase velocity and a high electromechanical coupling factor. Results obtained by first order perturbation theory are compared with those of a model based on the effective permittivity function of a multi-layer. The observed differences are being due to the high value of the εT dielectric constant and to the high coupling coefficient in the piezocomposites. The permittivity model predicts a nonzero attenuation, contrary to the first order perturbation calculations. It is shown that in the case of piezocomposites, only the permittivity model takes into account the strong interaction between the acoustic wave and the liquid.