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
Péclet 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 conduitâÂÂs 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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4686 |
| Date | 25 April 2007 |
| Creators | Sudarsan, Arjun Penubolu |
| Contributors | Ugaz, Victor M |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 4861755 bytes, electronic, application/pdf, born digital |
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