Flow Reversal in Traveling-Wave Electrokinetics: An Analysis of Forces Due to Ionic Concentration Gradients

Garcia-Sanchez, Pablo, Ramos, Antonio, Gonzalez, Antonio, Green, Nicolas G and Morgan, Hywel (2009) Flow Reversal in Traveling-Wave Electrokinetics: An Analysis of Forces Due to Ionic Concentration Gradients. Langmuir, 25, (9), 4988-4997. (doi:10.1021/la803651e).


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Pumping of electrolytes using ac electric fields from arrays of microelectrodes is a subject of current research. The behavior of fluids at low signal amplitudes (< 2-3 V-pp) is in qualitative agreement with the prediction of the ac electroosmosis theory. At higher voltages, this theory cannot account for the experimental observations. In some cases, net pumping is generated in the direction opposite to that predicted by the theory (flow reversal). In this work, we use fluorescent dyes to study the effect of ionic concentration gradients generated by Faradaic currents. We also evaluate the influence of factors such as the channel height and microelectrode array shape in the pumping of electrolytes with traveling-wave potentials. Induced charge beyond the Debye length is postulated to be responsible for the forces generating the observed flows at higher voltages. Numerical calculations are performed in order to illustrate the mechanisms that might be responsible for generating the flow.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1021/la803651e
Additional Information: Imported from ISI Web of Science
ISSNs: 0743-7463 (print)
1520-5827 (electronic)
Related URLs:
Divisions : Faculty of Physical Sciences and Engineering > Electronics and Computer Science
ePrint ID: 270024
Accepted Date and Publication Date:
Date Deposited: 21 Apr 2010 07:46
Last Modified: 31 Mar 2016 14:17
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/270024

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