Influence of liquid properties on the performance of S0‐mode Lamb wave sensors II: Experimental validation

Electro-acoustic sensors proving an adequate operation in liquid media are appropriate candidates for biosensing or liquid monitoring applications. In this context, electro-acoustic devices based on Lamb waves have been widely used for such purpose during the last years. More particularly, S0 mode Lamb wave resonators (S0-LWRs) have shown promising in-liquid performance. However, a theoretical background describing their in-liquid sensing mechanisms has only been published recently. In this work we present the experimental verification of the previously developed theoretical background based on a finite element model. We discuss about similarities and discrepancies between model and experiments, stating a final model correctly describing the in-liquid sensitivity features of S0-LWRs. These devices show appreciable different sensitivities of the resonant frequency to liquid viscosity and density, being more sensitive to the latter. Additionally, when they are not electrically isolated, the influence of the liquid electrical properties is superimposed to the mechanical ones and can be correctly extracted.