PRELIMINARY STUDY OF A POLYMER-BASED MICROFLUIDIC DEVICE FOR DETECTING DISTRIBUTED SHEAR LOADS

This paper reports on a polymer-based microfluidic device for detecting distributed shear loads. This device is comprised of a symmetric 3D polydimethylsiloxane (PDMS) microstructure, two electrolyte-filled microchannels embedded underneath the microstructure, and a set of electrode pairs distributed along the length of each microchannel. In conjunction with its electrode pairs, one body of electrolyte in each microchannel functions as distributed resistive transducers along the microchannel length. The 3D microstructure is built into a rectangular block with a narrow shear-loading bump on its top. The edges of the bump are aligned right at the width centers of the two microchannels. Thus, distributed shear loads acting on the bump translate to normal loads of opposite directions on the tops of the two microchannels, and consequently opposite geometrical changes in the microchannels, which register as resistance changes by the distributed resistive transducers. Together with a CNC mold, a two-mask photolithographic fabrication process is employed to fabricate a prototype device. The fabricated device is tested using a custom experimental setup. The experimental results validate the design concept of the device and further show that the device exhibits a linear response to shear loads with good repeatability.