Numerical Characterization of Compliance of Thick PDMS Microchannels

The purpose of this study is to characterize the dynamic response of fluid flow inside compliant microchannels such as the ones made of Polydimethylsiloxane (PDMS). This compliance can affect the accuracy of transient microfluidic experiments. We modeled the main effects of the compliance numerically to obtain the compliance as a function of microchannel dimensions without any fitting parameters as opposed to the ones available in the literature. We also modeled PDMS as a hyperelastic material to include its non-linear stress-strain relation. The model is based on the infinite thickness assumption and was determined to be valid when the PDMS thickness from all sides was higher than 3mm. The relationship obtained for the compliance provides a good fit for data outside of the study range with an error mostly within 4% based on the additional cases we simulated. The compliance was found to be non-linearly dependent on the cross-section with a slightly higher dependence on the height than the width. It also showed a linear dependence on the channel length.