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Issue 6, 2009
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DC-biased AC-electroosmotic and AC-electrothermal flow mixing in microchannels

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Abstract

This paper presents a novel approach of mixing two laminar flowing streams in microchannels. The mixer consists of a pair of electrodes disposed along a fluidic channel. By energizing the electrodes with a DC-biased (2.5 V) AC voltage (20 Vpp), an electrokinetic flow is induced with a flow profile perpendicular to that of the incoming laminar streams of liquids to be mixed. As a result, the flow lines of the incoming streams and the induced flow are forced to crossover and very efficient stirring and mixing at short mixing length can be achieved. The mixer can be operated from the AC-electroosmotic (ACEO) (σ = 1 mS/m, f = 100 kHz) to the AC-electrothermal (ACET) (σ = 500 mS/m, f = 500 kHz) flow regimes. The mixing efficiency in the ACEO regime was 92%, with a mixing length of 600 µm ([Q with combining dot above] = 2 µL/min), an estimated mixing time of 69 ms and an induced ACEO flow velocity of ∼725 µm/s. The mixing efficiency in the ACET regime was 65% for a mixing length of ∼1200 µm. The mixer is efficient and suitable for mixing reagents in a fluid media from low to high conductivity as required in diverse microfluidic applications.

Graphical abstract: DC-biased AC-electroosmotic and AC-electrothermal flow mixing in microchannels

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Publication details

The article was received on 06 Aug 2008, accepted on 31 Oct 2008 and first published on 28 Nov 2008


Article type: Paper
DOI: 10.1039/B813639D
Citation: Lab Chip, 2009,9, 802-809
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    DC-biased AC-electroosmotic and AC-electrothermal flow mixing in microchannels

    W. Y. Ng, S. Goh, Y. C. Lam, C. Yang and I. Rodríguez, Lab Chip, 2009, 9, 802
    DOI: 10.1039/B813639D

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