Quantitative assessment of acoustic pressure in one-dimensional acoustofluidic devices driven by standing surface acoustic waves

Abstract

Acoustofluidic devices based on standing surface acoustic waves (SSAWs) have shown great potential in the manipulation of particles and cells. However, characterizing the acoustic field in a microchannel is difficult. This work introduces an analytical acoustophoretic model that shows that, by identifying the time period of particle rearrangement and the width of the eventually formed “particle strip,” acoustic pressure amplitude in a one-dimensional (1D) SSAW-actuated microchamber could be estimated quantitatively. Experiments are carried out with the help of a micro-PIV (PIV: particle image velocimetry) system, the results of which show that in-channel acoustic pressure is proportional to the square of voltage and the duty factor of an applied pulsed signal. This work links external excitation with acoustic pressure via only one parameter, i.e., the electroacoustic scaling factor. The method is simple and effective enough to serve as a candidate for standardizing 1D SSAW-based acoustofluidic devices.