Formation of Bubbles and Droplets in Parallel, Coupled Flow-Focusing Geometries
Formation of Bubbles and Droplets in Parallel, Coupled Flow-Focusing Geometries
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DOI：
10.1002/smll.200800591
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发表时间：
2008-10-01
期刊：
影响因子：
13.3
通讯作者：
Whitesides, George M.
中科院分区：
文献类型：
--
作者：
Hashimoto, Michinao;Shevkoplyas, Sergey S.;Whitesides, George M.
本文介绍了以吐温20为表面活性剂的水中氮气气泡和水滴的形成机理。含有Span 80作为表面活性剂的十六烷。对这些微流控系统的研究比较了两个或四个耦合的流动聚焦发生器。通过共享进气口，提供连续相，并通过公共出口通道。在邻近区域形成气泡的过程。发生器与多种流动参数相互作用；气泡的形成在时间和空间上交替，气泡在出口通道中组装成复杂的图案。这些体系中气泡的形成动力学在很长一段时间内(至少10分钟)是稳定的。对于一定范围的流动参数，耦合的流动聚焦发生器在一组流动参数下表现出两种稳定的工作模式。耦合的流动聚焦发生器在十六烷中形成水滴的动力学更简单--相邻的发生器在所研究的整个流动参数范围内只产生单分散的液滴。这些观察结果表明，耦合聚焦流发生器之间的相互作用机制取决于分散相(如气体或液体)的可压缩性，以及由气泡或液滴破裂引起的聚焦流孔处压力的变化。
This paper describes the mechanism of formation of bubbles of nitrogen in water containing Tween 20 as a surfactant, and of droplets of water in. hexadecane containing Span 80 as a surfactant. The study of these micro-fluidic systems compares two or four flow-focusing generators coupled. through shared inlets, supplying the continuous phase, and through a common outlet channel. The processes that form bubbles in neighboring. generators interact for a wide range of flow parameters; the formation of bubbles alternates in time and space, and the bubbles assemble into complex patterns in the outlet channel. The dynamics of formation of bubbles in these systems are stable for long time (at least 10 min). For a certain range of flow parameters, the coupled flow-focusing generators exhibit two stable modes of operation for a single set of flow parameters. The dynamics of formation of droplets of water in hexadecane by the coupled flow-focusing generators are simpler - the adjacent generators produce only monodisperse droplets over the entire range of flow parameters that are explored. These observations suggest that the mechanism of interaction between coupled flow focusing generators relies on the compressibility of the dispersed phase (e.g., the gas or liquid), and on variations in pressure at the flow-focusing orifices induced by the breakup of bubbles or droplets.