Electrical Loading Effects on Leaky Lamb Waves for Piezoelectric Plate Bordered with a Fluid: Analysis and Measurements

Leaky Lamb waves are important research topics in the area of NDE and acoustic wave sensing technology. For waves propagating in a piezoelectric plate immersed in a fluid (dielectric or conductive), both mechanical and electrical loading effects present and result in phase velocity variation and wave attenuation. To quantitatively characterize these loading effects play an important role in various applications of these plate waves. In this work, we apply the partial wave theory for analyzing the fluid’s dielectric and conductive loading effects on an XZ-cut LiNbO3 plate. Both phase velocity variation and wave attenuation as a function of the fluid’s permittivity and conductivity are numerically determined. Furthermore, a new differential type measurement system is developed to accurately and sensitively measure the loading effects on the leaky Lamb waves. Good agreements between experimental data and numerical results are observed, which verifies the analytic model of the leaky Lamb wave and can be useful for further development of dielectric or conductivity sensors based on leaky Lamb waves.