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Copyright Brian J. Kirby. With questions, contact Prof. Kirby here. This material may not be distributed without the author's consent. When linking to these pages, please use the URL http://www.kirbyresearch.com/textbook.

This web posting is a draft, abridged version of the Cambridge University Press text. Follow the links to buy at Cambridge or Amazon or Powell's or Barnes and Noble. Contact Prof. Kirby here.

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Jump To: [Kinematics] [Couette/Poiseuille Flow] [Fluid Circuits] [Mixing] [Electrodynamics] [Electroosmosis] [Potential Flow] [Stokes Flow] [Debye Layer] [Zeta Potential] [Species Transport] [Separations] [Particle Electrophoresis] [DNA] [Nanofluidics] [Induced-Charge Effects] [DEP] [Solution Chemistry]

Chapter 13
Particle electrophoresis

As discussed earlier, electrophoresis is the motion of a charged body proportional to an electric field. Our earlier discussions regarding electrophoresis (Chapter 11) involved molecules; now we move on to discuss motion of charged particles. Particle electrophoresis is a straightforward way to manipulate particles in microfluidic devices, both for positioning and for separation; it is ubiquitous if electric fields are used for any purpose.

Particles and molecules differ in that small molecules can be treated as point chargesfrom the standpoint of how they perturb the surrounding electric field, and they cannot support enoughcounterions to create adouble layer. Particles (and also large macromolecules) have a large enough charge that they can be described as having an electrical double layer surrounding them. For large particles, electrophoresis is described using analyses similar to electroosmosis, albeit with different boundary conditions. For smaller particles, we account for the breakdown of the thin double layer assumption, leading to size-dependent electrophoretic velocity. Throughout, we are most concerned with the velocity of the particle, but the velocity of the fluid is closely related.

[Return to Table of Contents]



Jump To: [Kinematics] [Couette/Poiseuille Flow] [Fluid Circuits] [Mixing] [Electrodynamics] [Electroosmosis] [Potential Flow] [Stokes Flow] [Debye Layer] [Zeta Potential] [Species Transport] [Separations] [Particle Electrophoresis] [DNA] [Nanofluidics] [Induced-Charge Effects] [DEP] [Solution Chemistry]

Copyright Brian J. Kirby. Please contact Prof. Kirby here with questions or corrections. This material may not be distributed without the author's consent. When linking to these pages, please use the URL http://www.kirbyresearch.com/textbook.

This web posting is a draft, abridged version of the Cambridge University Press text. Follow the links to buy at Cambridge or Amazon or Powell's or Barnes and Noble. Contact Prof. Kirby here.