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Issue 10, 2011
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Suppressing the coffee stain effect: how to control colloidal self-assembly in evaporating drops using electrowetting

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Abstract

We study the influence of electrowetting on the formation of undesired solute residues, so-called coffee stains, during the evaporation of a drop containing non-volatile solvents. Electrowetting is found to suppress coffee stains of both colloidal particles of various sizes and DNA solutions at alternating (AC) frequencies ranging from a few Hertz to a few tens of kHz. Two main effects are shown to contribute to the suppression: (i) the time-dependent electrostatic force prevents pinning of the three phase contact line and (ii) internal flow fields generated by AC electrowetting counteract the evaporation driven flux and thereby prevent the accumulation of solutes along the contact line.

Graphical abstract: Suppressing the coffee stain effect: how to control colloidal self-assembly in evaporating drops using electrowetting

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Publication details

The article was received on 02 Feb 2011, accepted on 14 Mar 2011 and first published on 06 Apr 2011


Article type: Paper
DOI: 10.1039/C1SM05183K
Citation: Soft Matter, 2011,7, 4954-4958
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    Suppressing the coffee stain effect: how to control colloidal self-assembly in evaporating drops using electrowetting

    H. B. Eral, D. M. Augustine, M. H. G. Duits and F. Mugele, Soft Matter, 2011, 7, 4954
    DOI: 10.1039/C1SM05183K

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