1. Flow Restrictions and Fluid Turbulence in Microfluidic Channels By Joseph M. Clift

2. Outline Introduction Introduction Gate Design and Fabrication of Gated Channels Gate Design and Fabrication of Gated Channels Fabrication of Mixers Fabrication of Mixers Conclusions and Future Directions Conclusions and Future Directions

3. Why is it important? Microfluidic devices can be utilized for a wide range of applications such as Microfluidic devices can be utilized for a wide range of applications such as Biosensors 1,2 Biosensors 1,2 Microreactors 1,2 Microreactors 1,2 Image from http://thebigone.stanford.edu/ http://thebigone.stanford.edu/

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

5. Nonlithographic Fabrication Method

6. Microfluidic Gates Image taken of three microchannels of distances 165  m, 195  m, and 205  m at 34x. Image of 195  m microchannel at 50x. 200  m

7. Gate Dimensions

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

9. Nonlithographic Fabrication of Micromixers

10. Observations of mixing channels 400  m 100  m

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

12. Future Directions Evaluate fluid flow through the microgates Evaluate fluid flow through the microgates Model the fluid flow in the spiral- grooved micromixers Model the fluid flow in the spiral- grooved micromixers

13. References 1. 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/microfluidics.htm http://www.niherst.gov.tt/scipop/sci-bits/microfluidics.htm 2. 2. Whatis.com compiler. 2001 [cited 2007 Jul 24]. Microfluidics. Needham, MA: Whatis.com. Available from: http://whatis.techtarget.com/definition/0,,sid9_gci526632,0 0.html http://whatis.techtarget.com/definition/0,,sid9_gci526632,0 0.html 3. 3. Stephen R. Quake compiler. 2005 [cited 2007 Aug].. Stanford, CA: Quake Group homepage. Available from: http://thebigone.stanford.edu/ http://thebigone.stanford.edu/

14. Acknowledgements Dr. Vullev Dr. Vullev Marlon Thomas Marlon Thomas Connie Chong Connie Chong Brent Millare Brent Millare Amy Ferriera Amy Ferriera Elizabeth Zielins Elizabeth Zielins BRITE administration and members BRITE administration and members