Measurement of pressure drop and flow resistance in microchannels with integrated micropillars

Abstract

In the present study, we investigate single phase fluid flow through microchannels with integrated micropillars to calculate the pressure drop and flow resistance. The microchannels, which contain micropillars arranged in square and staggered arrangement, are fabricated in silicon substrate using standard photolithography and deep reactive ion etching (DRIE) techniques. The DRIE technique results in precise and accurate fabrication with smooth and vertical wall profiles. Pressure drop measurements are performed on microchannels with integrated micropillars under creeping flow regime over a range of water flow rates from 50 to 600 μl/min. It is observed that the pressure drop varies linearly with increasing flow rates. Flow resistance ( $$\Updelta P/Q$$ ) is calculated using the pressure drop values and is found to be decreasing as the Darcy number ( $$\sqrt{K/h^2}$$ ) increases. In general, the square arrangement of pillars offers higher resistance to flow than their staggered counterparts. It is observed that the existing theoretical models fail to accurately predict the permeability of the microchannel with integrated micro-pillars, particularly for cases where the micropillars have smooth and accurate geometric conformity, as obtained in the microfabricated structures used in the present study.