Abstract: This review aims to introduce the droplet-based microfluidics which has been growing rapidly in recent years. Some of the basic droplet operations are summarized focusing on fluid flow pattern, mass transfer and reaction both inside droplets and at interface of droplets. Some of typical examples of existing as well as potential applications of droplet-based microreactors in various fields are also discussed. The developed technologies and techniques provide means to precisely control droplet volumes and accurately manipulate behavior of individual droplet(e.g., generation of droplets, coalescence and fission, mixing and reactions inside the droplets). As a result, each individual droplet acts as a small batch reactor under confined conditions. Accordingly, these small flowing batch reactors together form a new type of novel continuous-flow reactors. Besides the usual advantages brought by microfluidics, e.g., intensified mass and heat transfer and easy scale-up, droplet-based microfluidics have unique features, such as ability to avoid cross contamination, rapid mixing of fluids inside the droplets, independent control of each droplet and high throughput. These features allow them to be widely used in many fields, such as preparation of functional materials, chemical synthesis, biochemical engineering, and so on.

Key words: multiphase flow, microreactor, droplet flow, micro-channel, fluid mechanics

摘要： 综述了近些年来快速发展的液滴微流控技术, 回顾了微流控系统中液滴的基本行为, 如液滴的生成、运动、聚并和分裂等研究进展, 重点探讨微液滴作为反应器其内部的流动、传质和反应过程, 以及液滴流微反应器已有的和潜在的重要应用价值。通过精确调控液滴在微尺度上的行为(产生、聚并与分裂、内部的混合与反应等), 使单个液滴成为新型受限空间内的微型间歇反应器, 而微通道内的液滴流进而形成了若干间歇反应器构成的连续流反应器新型式。除了微流控技术普遍具有的微小尺寸效应带来传质传热强化、易于放大等优势外, 液滴流微反应器还具有诸如避免试剂交叉污染、液滴内部可控混合、易于独立调控、便于高通量筛选或者制备等独特特点, 使得其在功能材料制备、化学合成以及生物化工方面有着广泛的应用。

关键词: 多相流, 微反应器, 液滴流, 微通道, 流体力学