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Droplets move over viscoelastic substrates by surfing a ridge.

ABSTRACT: Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a theory based on the substrate rheology. We quantitatively recover the dynamic contact angle and provide a mechanism for stick-slip motion when a drop is forced strongly: the contact line depins and slides down the wetting ridge, forming a new one after a transient. We anticipate that our theory will have implications in problems such as self-organization of cell tissues or the design of capillarity-based microrheometers.

SUBMITTER: Karpitschka S

PROVIDER: S-EPMC4532859 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Droplets move over viscoelastic substrates by surfing a ridge.

Karpitschka S S Das S S van Gorcum M M Perrin H H Andreotti B B Snoeijer J H JH

Nature communications 20150804

Liquid drops on soft solids generate strong deformations below the contact line, resulting from a balance of capillary and elastic forces. The movement of these drops may cause strong, potentially singular dissipation in the soft solid. Here we show that a drop on a soft substrate moves by surfing a ridge: the initially flat solid surface is deformed into a sharp ridge whose orientation angle depends on the contact line velocity. We measure this angle for water on a silicone gel and develop a th ...[more]

PMID: 26238436

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