Hydrodynamics in deformable microchannels

We report experimental investigations into deformable rectangular microchannels using pressure drop, wall deformation and microparticle image velocimetry analysis. The available theoretical framework for the deformation of the wall is reviewed, and a physical explanation is obtained for the non-dimensional deformable parameter a through scaling analysis based on the thick-plate approximation. A new theoretical model based on the thick-plate approximation is developed and compared against the experimentally obtained values. The effect of the thickness of the microchannel on the deformation is also discussed. The bulging effects of the microchannel are probed along the length of the channel, and the reduction in the pressure drop is compared against a non-deforming channel. We observe a larger effect of the deformation near the microchannel inlet than that toward the end of the channel. Furthermore, we observe an upper limit to the maximum deformation of the microchannel walls, and the increased flow rate in the channel does not contribute to any further deformation and thus the reduction in the overall pressure drop. Overall, the observations from a multitude of experiments in the current study will aid in the development of microfluidic systems for Lab-on-Chip applications using soft lithography and also demonstrate the measures to be taken during the fabrication of any polydimethylsiloxane based microfluidic systems.