2014/05/08 by Z. Li, Alexander M. Leshansky, Li, Z. +5
Engineering · Computer Science · #Innovative Microfluidic and Catalytic Techniques Innovation #Advanced Data Storage Technologies #Microfluidic and Capillary Electrophoresis Applications
paper · pdf · doi:10.48550/arxiv.1405.1923
In this paper we present a comprehensive study of the step-emulsification process for high-throughput production of (sub-)μm-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.