Electrowetting-induced oil film entrapment and instability

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Abstract

We investigate the spreading at variable rate of a water drop on a smooth hydrophobic substrate in an ambient oil bath driven by electrowetting. We find that a thin film of oil is entrapped under the drop. Its thickness is described by an extension of the Landau-Levich law of dip coating that includes the electrostatic pressure contribution. Once trapped, the thin film becomes unstable under the competing effects of the electrostatic pressure and surface tension and dewets into microscopic droplets, in agreement with a linear stability analysis. Our results recommend electrowetting as an efficient experimental approach to the fundamental problem of dynamic wetting in the presence of a tunable substrate-liquid interaction.
Original languageUndefined
Pages (from-to)167801-
JournalPhysical review letters
Volume97
Issue number16
DOIs
Publication statusPublished - 2006

Keywords

  • METIS-232972
  • IR-57510

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