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Issue 12, 2005
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Electrothermal stirring for heterogeneous immunoassays

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A technique is proposed to enhance microfluidic immuno-sensors, for example, immunoassays, in which a ligand immobilized on a microchannel wall specifically binds analyte flowing through the channel. These sensors can be limited in both response time and sensitivity by the diffusion of analyte to the sensing surface. In certain applications, the sensitivity and response of these heterogeneous immunoassays may be improved by using AC electrokinetically-driven microscale fluid motion to enhance antigen motion towards immobilized ligands. Specifically, the electrothermal effect is used to micro-stir analyte near the binding surface. Numerical simulations of antigen in a microchannel flow subjected to the electrothermal effect show that 6 Vrms applied to electrodes near a binding region can increase binding in the first few minutes by a factor of seven. The effectiveness of electrothermal stirring is a strong function of the Damköhler number. The greatest binding enhancement is possible for high Damköhler numbers, where the reaction is limited by diffusion. Based on these results, the utility of this technique for diffusion-limited microfluidic sensor applications is demonstrated.

Graphical abstract: Electrothermal stirring for heterogeneous immunoassays

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Publication details

The article was received on 10 Jun 2005, accepted on 13 Sep 2005 and first published on 06 Oct 2005

Article type: Paper
DOI: 10.1039/B508224B
Citation: Lab Chip, 2005,5, 1366-1373
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    Electrothermal stirring for heterogeneous immunoassays

    M. Sigurdson, D. Wang and C. D. Meinhart, Lab Chip, 2005, 5, 1366
    DOI: 10.1039/B508224B

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