Acoustoelectric interaction of plate modes with solutions

Acoustic plate mode (APM) devices operating in liquids have an associated electric field which extends several micrometers into the liquid and is capable of interacting with ions and dipoles in solution. Experiments have been performed using quartz APM devices which demonstrate these acoustoelectric interactions. Changes in the dielectric constant or conductivity of solutions in contact with the device were found to perturb the propagation velocity of the plate mode. An equivalent circuit is proposed to describe the interaction of the electric field with ions and dipoles. From this simple model we obtain the velocity shift and attenuation which should occur as a result of this interaction and compare the model predictions to the experimentally observed trends.