Sensing in liquids using acoustic plate mode devices

Acoustic plate mode devices fabricated on ST-quartz and operating at 158 MHz have been used to measure both liquid viscosity and changes in surface mass caused by accumulation of species from a liquid. A new model is proposed to explain the observed perturbation in plate mode propagation characteristics caused by viscous coupling of liquids and by mass accumulation at the solid/liquid interface. Measurements confirm the dependence of plate mode attenuation on the square root of viscosity and of velocity perturbation on surface mass density.