Wetting morphologies at microstructured surfaces

Ralf Seemann, Martin Brinkmann, Edward Kramer, Frederick Lange, Reinhard Lipowsky

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320 Citations (Scopus)

Abstract

The wetting of microstructured surfaces is studied both experimentally and theoretically. Even relatively simple surface topographies such as grooves with rectangular cross section exhibit a large variety of different wetting morphologies as observed by atomic force microscopy. This polymorphism arises from liquid wedge formation along the groove corners and from contact line pinning along the groove edges. A global morphology diagram is derived that depends only on two system parameters: (i) the aspect ratio of the groove geometry and (ii) The contact angle of the underlying substrate material. For microfluidics, the most interesting shape regimes involve extended liquid filaments, which can grow and shrink in length while their cross section stays essentially constant. Thus, any method by which one can vary the contact angle can be used to switch the length of the filament, as is demonstrated in the context of electrowetting.
Original languageEnglish
Pages (from-to)1848-1852
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number6
Early online date27 Jan 2005
DOIs
Publication statusPublished - 8 Feb 2005

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