Flow Restrictions and Fluid Turbulence in Microfluidic Channels

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Flow Restrictions and Fluid Turbulence in
Microfluidic Channels

• By Joseph M. Clift

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Outline

• Introduction
• Gate Design and Fabrication of Gated Channels
• Fabrication of Mixers
• Conclusions and Future Directions

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Why is it important?

• Microfluidic devices can be utilized for a wide
  range of applications such as
• Biosensors1,2
• Microreactors1,2

Image from http//thebigone.stanford.edu/
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Fabrication of Gates

• Gated channels are produced on Macromedia
  Freehand.
• The finished drawings are then printed on a
  transparency from high resolution laser printer
  and cut to fit into the petri dishes.

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Nonlithographic Fabrication Method
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Microfluidic Gates
200mm
200mm
Image taken of three microchannels of distances
165mm, 195mm, and 205mm at 34x.
Image of 195mm microchannel at 50x.
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Gate Dimensions
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Microfluidic Mixers

• Small cross sections and large linear flow
  velocity leads to laminar flows
• Mixing is essential for biosensors (labeling of
  samples) and microreactors
• Active mixers moving stirrers
• Passive mixers no moving parts, the cannel
  geometry generates intertwining flows

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Nonlithographic Fabrication of Micromixers
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Observations of mixing channels
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Conclusions

• Nonlithographic fabrication is a facile and
  low-cost alternatives for expedient prototyping.
• Microgate fabrication exceeded twice the
  resolution of the printers we used.
• Nonlithographic methods allow for the fabrication
  of circular channels with patterned walls.
• Spiral grooves along the walls of micromixers
  significantly increases the mixing efficiency.

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Future Directions

• Evaluate fluid flow through the microgates
• Model the fluid flow in the spiral-grooved
  micromixers

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References

1. Trinidad National Institute of Higher Education
   compiler. 2001 cited 2007 Jul 24. Make Way for
   Microfluidics! Trinidad NIHERST. Available from
   http//www.niherst.gov.tt/scipop/sci-bits/microflu
   idics.htm
2. Whatis.com compiler. 2001 cited 2007 Jul 24.
   Microfluidics. Needham, MA Whatis.com. Available
   from http//whatis.techtarget.com/definition/0,,s
   id9_gci526632,00.html
3. Stephen R. Quake compiler. 2005 cited 2007
   Aug.. Stanford, CA Quake Group homepage.
   Available from http//thebigone.stanford.edu/

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Acknowledgements

• Dr. Vullev
• Marlon Thomas
• Connie Chong
• Brent Millare
• Amy Ferriera
• Elizabeth Zielins

• BRITE administration and members