Liquid Viscosity Measurement Using Plate Mode Shear Horizontal Waves on a Piezoelectric Ceramic Thin Plate

Numerical analysis results of the propagation characteristics of multiple mode shear horizontal (SH) waves along a piezoelectric ceramic thin plate with liquid loading on one of two boundary surfaces are described. The fractional phase velocity changes for S0, A0 and S1 mode SH waves have linear dependences on the square root of liquid viscosity under the electrically shorted boundary condition of both surfaces of the substrate. The mechanical displacement in the liquid layer decays exponentially with the distance from the substrate-liquid interface. The existing depth of the displacement in the liquid layer increases with liquid viscosity in the form of a linear relationship to the square root of liquid viscosity. The measurement of liquid viscosity using two modes of SH waves is carried out. The measured results for water solutions of glycerol using S0 and A0 mode SH waves show linear dependences between the fractional velocity change and the square root of liquid viscosity, and are consistent with the theoretical values.