Acoustic waves at the solid/liquid interface

The coupling of acoustic waves across interfacial boundaries depends upon the morphology of the surface and the orientation of the waves at the boundary. The dependence of the wave propagation at the boundary as a function of the physical properties of the liquid is described. The primary influence comes from the density and viscosity. However, the electrical conductivity of the liquid may also contribute to the interactions at such boundaries. The structure of the interface is an important parameter in discriminating the influences of the density and viscosity of the liquid. It is possible to optimise the surface structure for sensitivity to either density or viscosity and to achieve a high sensitivity to liquid densities despite samples with a broad range of viscosities. The influence of surface morphology of the thickness shear mode resonator on the liquid properties is studied by using different structured electrodes to separate the density and viscosity of the liquid. Finally, a sensor was developed to measure antifreeze concentration in water.