Microchannel electrokinetics of charged analytes in buffered solutions near floating electrodes

Mathias Bækbo Andersen (Invited author), Trevor Wolfcale (Invited author), Misha Marie Gregersen (Invited author), Sumita Pennathur (Invited author), Henrik Bruus (Invited author)

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    Abstract

    We present both experimental and numerical studies of nonlinear electrokinetic flow of buffered solutions seeded with dilute analytes in a straight microchannel (0.6 μm high, 250 μm wide, and 9000 μm long) with a 0.15 μm high 60 μm wide electrode situated at the bottom center of the channel. Such studies will enable a fundamental understanding of nonlinear transport effects of ions in electrolyte systems with a significant Debye screening layer. Initial experimental studies have shown an order of magnitude increase of concentration near the electrodes, but numerical studies have so far failed to accurately predict such behavior in these flow regimes. Experimentally, using conventional fluorescence microscopy, we investigated the concentration gradient (as well as the associated electroosmosis, induced-charge electro-osmosis, and electrophoresis) of the charged analyte near the floating electrode as a function of analyte (1 to 10 μM fluorescein and bodipy) and buffer (1 to 10 mM borate and posphate) concentrations and an externally applied voltage drop (50 to 100 V) along the channel. We have implemented a nonlinear continuum kinetics model of the system involving the electric potential, the buffer flow velocity, the pressure, and the four ionic concentration fields and compared the resulting numerical simulations with experiments.
    Original languageEnglish
    Publication date2009
    Publication statusPublished - 2009
    Event80. annual meeting of the international association of applied mathematics and mechanics : GAMM 2009 - Gdansk, Poland
    Duration: 1 Jan 2009 → …
    Conference number: 80

    Conference

    Conference80. annual meeting of the international association of applied mathematics and mechanics : GAMM 2009
    Number80
    CityGdansk, Poland
    Period01/01/2009 → …

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