Trapping Microfluidic Drops in Wells of Surface Energy

Rémi Dangla, Sungyon Lee, and Charles N. Baroud
Phys. Rev. Lett. 107, 124501 – Published 15 September 2011

Abstract

A small hole etched in the top of a wide microchannel creates a well of surface energy for a confined drop. This produces an attractive force Fγ equal to the energy gradient, which is estimated from geometric arguments. We use the drag Fd from an outer flow to probe the trapping mechanism. When Fd<Fγ, the drop deforms but remains anchored to the hole. Its shape provides information about the pressure field. At higher flow velocities, the drop detaches, defining a critical capillary number for which Fd=Fγ. The measured anchoring force agrees with the geometric model.

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  • Received 15 March 2011

DOI:https://doi.org/10.1103/PhysRevLett.107.124501

© 2011 American Physical Society

Authors & Affiliations

Rémi Dangla, Sungyon Lee, and Charles N. Baroud*

  • LadHyX and department of Mechanics, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France

  • *baroud@ladhyx.polytechnique.fr

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Vol. 107, Iss. 12 — 16 September 2011

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