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Zipping Effect on Omniphobic Surfaces for Controlled Deposition of Minute Amounts of Fluid or Colloids

Authors

  • Renaud Dufour,

    1. University Lille Nord de France, Villeneuve d'Ascq, Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Villeneuve d'Ascq, France
    2. University Lille Nord de France, Villeneuve d'Ascq, Interdisciplinary Research Institute (IRI), USR CNRS 3078, Parc de la Haute Borne, Avenue de Halley, 59658 Villeneuve d'Ascq, France
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  • Philippe Brunet,

    1. Laboratoire Matière et Systèmes Complexes, UMR CNRS 7057, Batiment Condorcet, 10 rue Alice Domont et Léonie Duquet, 75205 Paris cedex 13, France
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  • Maxime Harnois,

    1. University Lille Nord de France, Villeneuve d'Ascq, Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Villeneuve d'Ascq, France
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  • Rabah Boukherroub,

    1. University Lille Nord de France, Villeneuve d'Ascq, Interdisciplinary Research Institute (IRI), USR CNRS 3078, Parc de la Haute Borne, Avenue de Halley, 59658 Villeneuve d'Ascq, France
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  • Vincent Thomy,

    1. University Lille Nord de France, Villeneuve d'Ascq, Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Villeneuve d'Ascq, France
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  • Vincent Senez

    Corresponding author
    1. University Lille Nord de France, Villeneuve d'Ascq, Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Villeneuve d'Ascq, France
    • University Lille Nord de France, Villeneuve d'Ascq, Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, Villeneuve d'Ascq, France.
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Abstract

When a drop sits on a highly liquid-repellent surface (super-hydrophobic or super-omniphobic) made of periodic micrometer-sized posts, its contact-line can recede with very weak mechanical retention providing that the liquid stays on top of the microsized posts. Occurring in both sliding and evaporation processes, the achievement of low-contact-angle hysteresis (low retention) is required for discrete microfluidic applications involving liquid motion or self-cleaning; however, careful examination shows that during receding, a minute amount of liquid is left on top of the posts lying at the receding edge of the drop. For the first time, the heterogeneities of these deposits along the drop-receding contact-line are underlined. Both nonvolatile liquid and particle-laden water are used to quantitatively characterize what rules the volume distribution of deposited liquid. The experiments suggest that the dynamics of the liquid de-pinning cascade is likely to select the volume left on a specific post, involving the pinch-off and detachment of a liquid bridge. In an applied prospective, this phenomenon dismisses such surfaces for self-cleaning purposes, but offers an original way to deposit controlled amounts of liquid and (bio)-particles at well-targeted locations.

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