Electrokinetic particle separation in a single-spiral microchannel

John Dubose, Junjie Zhu, Saurin Patel, Xinyu Lu, Nathaniel Tupper, John M. Stonaker, Xiangchun Xuan

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


The efficient separation of discrete particle species is a topic of interest in numerous research fields for its practical application to problems encountered in both academia and industry. We have recently developed an electrokinetic technique that exploits the curvature-induced dielectrophoresis (C-iDEP) to continuously sort particles by inherent properties in asymmetric double-spiral microchannels. Herein we demonstrate that a single-spiral microchannel is also sufficient for a continuous-flow sheathless electrokinetic particle separation. This method relies on C-iDEP to focus particles to a tight stream and the wall-induced electric lift to manipulate the aligned particles to size-dependent equilibrium positions, both of which happen simultaneously inside the spiral. A theoretical model is developed to understand this size-based separation, which has been implemented for both a binary mixture and a ternary mixture of colloidal particles. The obtained analytical formulae predict with a close agreement both the experimentally measured particle center-wall distance and the necessary electric field for a complete particle focusing in the spiral.

Original languageEnglish (US)
Article number115018
JournalJournal of Micromechanics and Microengineering
Issue number11
StatePublished - Nov 1 2014

Bibliographical note

Publisher Copyright:
© 2014 IOP Publishing Ltd.


  • dielectrophoresis
  • electrokinetics
  • microfluidics
  • separation
  • single spiral


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