Acoustic resonances in straight micro channels:: Beyond the 1D-approximation

Acoustic actuation can be used to perform several tasks in microfluidic systems. In this paper, we investigate an acoustic separator through micro-PIV analysis in stop-flow mode and numerical simulations, and a good agreement between the two is found. Moreover, we demonstrate that it is not sufficient only to characterize devices in flow-through mode, since in these systems much different resonant patterns can result in similarly looking band formations. Furthermore, we conclude that extended 1D approximations of the acoustic radiation force are inadvisable, and instead, a 2D model is preferred. The results presented here provide valuable insight into the nature and functionality of acoustic microdevices, and should be useful in the interpretation and understanding of the same.