Modeling of Microdevices for SAW-Based Acoustophoresis ?￠???? A Study of Boundary Conditions

摘要

We present a ?ˉ????nite-element method modeling of acoustophoretic devices consisting of a single, long, straight, water-?ˉ????lled microchannel surrounded by an elastic wall of either borosilicate glass (pyrex) or the elastomer polydimethylsiloxane (PDMS) and placed on top of a piezoelectric transducer that actuates the device by surface acoustic waves (SAW). We compare the resulting acoustic ?ˉ????elds in these full solid-?ˉ????uid models with those obtained in reduced ?ˉ????uid models comprising of only a water domain with simpli?ˉ????ed, approximate boundary conditions representing the surrounding solids. The reduced models are found to only approximate the acoustically hard pyrex systems to a limited degree for large wall thicknesses and but not very well for acoustically soft PDMS systems shorter than the PDMS damping length of 3 mm.