Droplet Formation and Emulsification using Microfluidic Channels: A Review

Abstract

For the production of simple to complex emulsions, Microfluidic channels are becoming encouraging devices for the future. Microfluidic provides an investigation platform where the fluid quantity is in micro scale or nano scale. So performing experiments and investigation with the help of miniature devices offers numerous benefits such as very small quantity requirements of reagents, reduced wastage, and high control. There are several significant fluid dynamic applications at the micro-scale level, for instance, drug delivery (pharmaceuticals), flow chemistry, food processing, biotechnology, Industrial and environment sciences, life sciences and microbiology, etc. For the synthesis of emulsions through bulk emulsion procedure, the required accuracy in size and structure of fluid droplets usually get scarified. However, an emulsion can form accurately by fabricating even a single drop at a time with the help of micro fluidic devices. Also, the formation of highly mono disperse emulsion droplets is possible by using various microfluidic channel configurations. Further, the fabrication of higher-order or complex emulsions with the precise control over their structures can also be possible with this technology. The present article is presenting a review on the mechanism of generation of stable emulsion byusing microfluidic channels. The droplet generation mechanism is complex process where interfacial tension, viscous force, inertia effect and other geometrical parameters collectively govern the breakup process. For emulsion generation, various passive methods like Flow focusing, Co-flowing, membrane emulsification and T-shape junctions with their governing mechanism are discussed. Also the effect of physical parameters such as temperature, viscosity and interfacial tension are summarized in this article.