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Microfluidics and Nanofluidics

, Volume 1, Issue 4, pp 319–327 | Cite as

A sequential injection microfluidic mixing strategy

  • Jeffrey T. Coleman
  • David Sinton
Research Paper

Abstract

A novel micromixing strategy is presented, which exploits the axial diffusion of a continuous sequence of discrete samples in a microchannel expansion. Mixing of a continuous sequence in an electroosmotic flow through a sudden expansion region is first modeled assuming an ideal, square-wave injection. The effect of expansion geometry and injection frequency is investigated. To facilitate sequential injection on-chip, two new sequential sample injection schemes are developed and coupled with an expansion region. The first of these designs produces two sample pairs that flow out of separate channels into a common expansion region. This design results in high axial mixing rates but an inherent bias in the injector produces significant cross-stream concentration gradients in the output. These results indicate that the effectiveness of this micromixing strategy is critically dependant on the injection method. A second injector design effectively eliminates the effect of the injection bias using a symmetric microchannel configuration with three solution inlets. The resulting symmetrical injection micromixer produces a continuous uniform stream, 99% mixed, in only 2.3 mm.

Keywords

Microfluidic Mixing Electrokinetic Sequential injection Alternating injection Computational modeling 

Notes

Acknowledgments

Financial support of this work by the Natural Sciences and Engineering Research Council (NSERC) of Canada, through research grants to D.S., is gratefully acknowledged. Financial support from the Advanced Systems Institute of British Columbia, through a research award, is also gratefully acknowledged.

References

  1. Alarie JP, Jacobson SC, Ramsey JM (2001) Electrophoretic injection bias in a microchip valving scheme. Electrophoresis 22:312–317Google Scholar
  2. Bianchi F, Ferrigno R, Girault HH (2000) Finite element simulation of an electroosmotic-driven flow division at a T-junction of microscale dimensions. Anal Chem 72:1987–1993Google Scholar
  3. Biddiss E, Erickson D, Li D (2004) Heterogeneous surface charge enhanced micromixing for electrokinetic flows. Anal Chem 76:3208–3213Google Scholar
  4. Deshmukh AA, Liepmann D, Pisano AP (2001) Characterization of a micro-mixing, pumping, and valving system. In: Proceedings of the 11th international conference on solid-state sensors and actuators (Transducers 2001), Munich, Germany, June 2001, pp 779–782Google Scholar
  5. Erickson D, Li D (2002) Influence of surface heterogeneity on electrokinetically driven microfluidic mixing. Langmuir 18:1883–1892Google Scholar
  6. Erickson D, Sinton D, Li D (2003) Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems. Lab Chip 3:141–149Google Scholar
  7. Ermakov SV, Jacobson, SC, Ramsey JM (1998) Computer simulations of electrokinetic transport in microfabricated channel structures. Anal Chem 70:4494–4504Google Scholar
  8. Ermakov SV, Jacobson SC, Ramsey JM (2000) Computer simulations of electrokinetic injection techniques in microfluidic devices. Anal Chem 7:3512–3517Google Scholar
  9. Fujii T, Sando Y, Higashino K, Fugii Y (2003) A plug and play microfluidic device. Lab Chip 3:193–197Google Scholar
  10. Jacobson SC, Culbertson CT, Daler JE, Ramsey JM (1998) Microchip structures for submillisecond electrophoresis. Anal Chem 70:3476–3480Google Scholar
  11. Jeon NL, Dertinger KW, Chiu DT, Choi IS, Stroock AD, Whitesides GM (2000) Generation of solution and surface gradients using microfluidic systems. Langmuir 16:8311–8316Google Scholar
  12. Johnson TJ, Ross D, Locascio LE (2002) Rapid microfluidic mixing. Anal Chem 74:45–51Google Scholar
  13. Liu RH, Stremler MA, Sharp KV, Olsen MG, Santiago JG, Adrian RJ, Aref H, Beebe DJ (2000) Passive mixing in a three-dimensional serpentine microchannel. J MEMS 9:190–197Google Scholar
  14. Oddy MH, Santiago JG, Mikkelsen JC (2001) Electrokinetic instability micromixing. Anal Chem 73:5822–5832Google Scholar
  15. Patankar NA, Hu HH (1998) Numerical simulation of electroosmotic flow. Anal Chem 70:1870–1881Google Scholar
  16. Santiago JG (2001) Electroosmotic flows in microchannels with finite inertial and pressure forces. Anal Chem 73:2353–2365Google Scholar
  17. Sinton D, Ren L, Li D (2003a) A dynamic loading method for controlling on-chip microfluidic sample injection. J Colloid Interface Sci 266:448–456Google Scholar
  18. Sinton D, Ren L, Xuan X, Li D (2003b) Effects of liquid conductivity differences on multi-component sample injection, pumping and stacking in microfluidic chips. Lab Chip 3:173–179Google Scholar
  19. Stone HA, Stroock AD, Ajdari A (2004) Engineering flows in small devices: microfluidics towards a lab-on-a-chip. Annu Rev Fluid Mech 36:381–411Google Scholar
  20. Stroock AD, Dertinger SKW, Ajdari A, Mezić I, Stone HA, Whitesides GM (2002) Chaotic mixer for microchannels. Science 295:647–651Google Scholar
  21. Tang Z, Hong S, Djukic D, Modi V, West AC, Yardley J, Osgood RM (2002) Electrokinetic flow control for composition modulation in a microchannel. J Micromech Microeng 12:870–877Google Scholar

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringUniversity of VictoriaVictoriaCanada

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