Multivortex micromixing: novel techniques using Dean flows for passive microfluidic mixing

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Title: Multivortex micromixing: novel techniques using Dean flows for passive microfluidic mixing
Author: Sudarsan, Arjun Penubolu
Abstract: Mixing of fluids at the microscale poses a variety of challenges , many of which arise from the fact that molecular diffusion is the dominant transport mechanism in the laminar flow regime . The unfavorable combination of low Reynolds numbers and high P ? ? ? ?clet numbers implies that cumbersomely long microchannels are required to achieve efficient levels of micromixing . Although considerable progress has been made toward overcoming these limitations (e .g . , exploiting chaotic effects ) , many techniques employ intricate 3 -D flow networks whose complexity can make them difficult to build and operate . In this research , we show that enhanced micromixing can be achieved using topologically simple and easily fabricated planar 2 -D microchannels by simply introducing curvature and changes in width in a prescribed manner . This is accomplished by harnessing a synergistic combination of (i ) Dean vortices that arise in the vertical plane of curved channels as a consequence of an interplay between inertial , centrifugal , and viscous effects , and (ii ) expansion vortices that arise in the horizontal plane due to an abrupt increase in a conduit ? ? ? ? ? ?s cross -sectional area . We characterize these effects using top -view imaging of aqueous streams labeled with tracer dyes and confocal microscopy of aqueous fluorescent dye streams , and by observing binding interactions between an intercalating dye and double -stranded DNA . These mixing approaches are versatile , scalable , and can be straightforwardly integrated as generic components in a variety of lab -on -a -chip systems .
URI: http : / /hdl .handle .net /1969 .1 /4686
Date: 2007-04-25

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Multivortex micromixing: novel techniques using Dean flows for passive microfluidic mixing. Available electronically from http : / /hdl .handle .net /1969 .1 /4686 .

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