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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Electrokinetic Focusing of Colloidal Particles by Joule Heating Induced Temperature Gradient in a Convergent-Divergent Microfluidic Structure

Get access (open in a dialog) DOI: 10.1615/IHTC15.nmm.009618
pages 5473-5481

Résumé

Electrokinetic enrichment of colloidal particles is demonstrated experimentally for the first time with the use of Joule heating induced temperature gradient focusing (TGF) in a microfluidic convergent-divergent structure. It is proposed that application of an external electric field to the microfluidic structure introduces four mechanisms of particle transport: advection due to electroosmosis, electrophoresis, dielectrophoresis and thermophoresis (due to the Joule-heating induced temperature gradient). Parametric studies under various experimental conditions (effects of electric field, particle size) are performed for examining the effectiveness of the method. It is experimentally determined that the particle dielectrophoresis (thermophoresis) dominates the enrichment of larger (smaller) particles, and in either case the combined effect of electroosmosis-induced advection and electrophoresis is mainly to transport the particles to the zone of enrichment (the narrowest constriction of convergent-divergent structure). In addition, the enrichment of particles is shown to be achieved with the use of combined DC and AC voltages rather than a sole DC or AC voltage.