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

Burak Eral, Dileep Mampallil Augustine, Michael H.G. Duits, Friedrich Gunther Mugele

Research output: Contribution to journalArticleAcademicpeer-review

212 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)4954-4958
Number of pages5
JournalSoft matter
Volume7
Issue number10
DOIs
Publication statusPublished - 2011

Keywords

  • IR-104499
  • METIS-279914

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