Competition between Induced-Charge Electro-Osmosis and Electrothermal Effects at Low Frequencies around a Weakly Polarizable Microchannel Corner

Matan Zehavi, Alicia Boymelgreen, Gilad Yossifon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

Sharp corners are an inherent component of most planar microfluidic systems, and thus their influence on flow within the microchannel is of significant interest. Here, we demonstrate that in electrokinetically driven devices, the presence of a sharp corner may result in localized vortices due to nonlinear induced-charge electro-osmosis (ICEO) and/or electrothermal forces. Application of an alternating-current electric field enables quantification of the nonlinear ICEO ejection-flow effect by isolating it from linear electro-osmotic background flow which is present under dc forcing. The hydrodynamic flow in the vicinity of a sharp channel corner is analyzed using experimental micro-particle-image-velocimetry and numerical simulations for different buffer concentrations, frequencies, and applied voltages. Divergence from the purely ICEO flow with increasing buffer conductivity is shown to be a result of increasing electrothermal effects due to Joule heating.

Original languageEnglish
Article number044013
JournalPhysical Review Applied
Volume5
Issue number4
DOIs
StatePublished - 20 Apr 2016
Externally publishedYes

Funding

FundersFunder number
Russell Berrie Nanotechnology Institute
Technion RBNI
Israel Science Foundation1078/10

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