Abstract
Controlling and manipulating liquids and analytes at the sub-millimeter scale is a challenge that frequently requires new methods to be developed. Indeed, scaling-down of traditional macroscopic ideas often fails. For instance, pumping liquids using pressure differences is often impractical and counterproductive because the resulting parabolic flow profile deforms sample zones. As the size of the system shrinks, the surface-to-volume ratio increases and interfacial effects become dominant. This actually opens new possibilities since the phenomenon of electroosmotic flow (EOF), wherein a fluid is made to move relative to a stationary charged boundary, can then be exploited to design efficient microfluidic devices. In this chapter, we review the fundamental principles of EOF as well as some of the methods used to coat channel walls and reduce the impact of EOF in situations where it would be unfavorable for the device performance.
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Further Reading
The present chapter is a simple introduction to the physics of EOF and the control of EOF via polymer coating. The following references are highly recommended: (4) is perhaps the best review of the electrophoresis of macromolecules; (10) is a superb review of electrokinetic phenomena in microfluidic devices and covers more materials that we could explore here; (13) is an extensive review of polymer coating; (22) is a great survey of some of the mathematical aspects of EOF.
Acknowledgments
K.K. would like to acknowledge the financial support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and of NATO for a postdoctoral fellowship. GWS would like to thank NSERC for a Discovery Grant. F.T. would like to thank the University of Ottawa for an admission scholarship.
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Slater, G.W., Tessier, F., Kopecka, K. (2010). The Electroosmotic Flow (EOF). In: Hughes, M., Hoettges, K. (eds) Microengineering in Biotechnology. Methods in Molecular Biology, vol 583. Humana Press, Totowa, NJ. https://doi.org/10.1007/978-1-60327-106-6_5
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DOI: https://doi.org/10.1007/978-1-60327-106-6_5
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