Quasistatic Microdroplet Production in a Capillary Trap

M. Valet , L.L. Pontani , A. Prevost , E. Wandersman

Bibtex , Full text PDF
Phys. Rev. Applied, 9, 014002
Published 15 Feb. 2018
DOI: https://doi.org/10.1103/PhysRevApplied.9.014002

Abstract

We develop a method to produce aqueous microdroplets in an oil phase, based on the periodicextraction of a pending droplet across the oil-air interface. This interface forms a capillary trapinside which a droplet can be captured and detached. This process is found to be capillary based andquasistatic. The droplet size and emission rate are independently governed by the injected volume percycle and the extraction frequency. We find that the minimum droplet diameter is close to the injectionglass-capillary diameter and that variations in surface tension moderately perturb the droplet size. Atheoretical model based on surface energy minimization in the oil-water-air phases is derived andcaptures the experimental results. This method enables robust, versatile, and tunable production ofmicrodroplets at low production rates.

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Mechanics of integrated and artificial biological systems