Simulation and verification of polydimethylsiloxane (PDMS) channels on acoustic microfluidic devices

Abstract

Polydimethylsiloxane (PDMS) is widely used as a channel material in microfluidic applications. Due to its highly elastomeric characteristics, PDMS absorbs the acoustic energy of the surface acoustic waves (SAWs) generated by the interdigital transducers (IDTs). Insertion loss is one of the indicators that present the degree of attenuation caused by the PDMS channels for SAW devices. In this paper, we investigate the effect of PDMS channel side wall thickness on insertion loss via ANSYS(A (R)) Finite Element (FE) Modelling software (ANSYS Inc., Canonsburg, PA). The 3-Dimensional simulation study was carried out in two main steps; first, a calibration step of bare 128A degrees YX-cut lithium niobate LiNbO3 for obtaining the boundary conditions and second, with the PDMS channels constructed on top of the substrate. The PDMS channel side wall thickness was varied between 2 and 8 mm and the results were compared with experimental results of a prior study. The results illustrate that insertion loss is increased as the PDMS side wall thickness is increased highlighting the need to minimize the PDMS side wall thickness in the design.