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arXiv · 1405.1923

Step-emulsification in nanofluidic device

Z. Li·A. M. Leshansky·L. M. Pismen·P. Tabeling
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Abstract

In this paper we present a comprehensive study of the step-emulsification process for high-throughput production of (sub-)$\mu$m-size monodisperse droplets. The microfluidic device combines a Hele-Shaw nanofluidic cell with a step-like outlet to a deep and wide reservoir. The proposed theory based on Hele-Shaw hydrodynamics provides the quasi-static shape of the free boundary between the disperse liquid phase engulfed by the co-flowing continuous phase prior to transition to oscillatory step-emulsification at low enough capillary number. At the transition the proposed theory anticipates a simple condition for critical capillary number as a function of the Hele-Shaw cell geometry. The transition threshold is in excellent agreement with experimental data. A simple closed-form expression for the size of the droplets generated in step-emulsification regime derived using simple geometric arguments also shows a very good agreement with the experimental results.

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Z. Li, A. M. Leshansky, L. M. Pismen, P. Tabeling. 2014-05-08. Step-emulsification in nanofluidic device. https://arxiv.org/abs/1405.1923

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