Effect of Liquid Viscosity on the Properties of Higher-Order Acoustic Waves in a YX Cut Lithium Niobate Plate

The work investigates the effect of liquid viscosity on the characteristics of antisymmetric (An) and symmetric (Sn) Lamb waves and shear-horizontally polarized waves (SHn) of the first, second, and third orders (SH1, A1, S2, S3, and SH3) propagating in a YX cut lithium niobate plate. A one port device is considered, in which the transmitting and receiving interdigital transducers (IDTs) are combined. Aqueous solutions of glycerin with different concentrations were used as the test liquid. The viscosity of the solution was varied in the range of 0.89-934 cP. In the considered frequency range, the A1 wave was a backward wave. The obtained results show that, due to the large magnitude of the mechanical displacement component normal to the plate surface, the A1, S2, and S3 waves are strongly attenuated in the presence of a viscous liquid and, unlike the SH1 and SH3 waves, are unsuitable for creating liquid viscosity sensors. However, the SH1 and SH3 waves in this propagation direction show the potential for developing effective liquid viscosity sensors based on them in different ranges.