Speed of flow of individual droplets in microfluidic channels as a function of the capillary number, volume of droplets and contrast of viscosities
Speed of flow of individual droplets in microfluidic channels as a function of the capillary number, volume of droplets and contrast of viscosities
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DOI：
10.1039/c1lc20534j
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发表时间：
2011-01-01
期刊：
影响因子：
6.1
通讯作者：
Garstecki, Piotr
中科院分区：
文献类型：
--
作者：
Jakiela, Slawomir;Makulska, Sylwia;Garstecki, Piotr
液滴微流控技术在通量（即每秒反应）和控制它们所需的输入/输出控制数量之间提供了一个有吸引力的折衷方案。控制数量的减少主要是由于限制了流段在通道中的一维流动，而这种流动又严重依赖于液滴的流动速度。这个速度是许多参数的复杂函数，包括液滴的体积（或段塞的长度L），它们的粘度mu(d)，粘度mu(c)和连续相的流速，界面张力和通道横截面的几何形状。系统地筛选这些参数对液滴速度的影响仍然是一个悬而未决的挑战。在这里，我们详细介绍了一个自动化系统，该系统以每小时高达2000次实验的速度筛选单个液滴的速度，精度高，无需人为干预。测量的结果在渠道广场截面的宽度w = 360μm)(四个不同的值的对比粘度λ=μ(d) /μ(c) = 0.3, 1, 3,和33岁的大范围的毛细管数Ca是一个元素的值(10(4)10(1)),和宽范围的长度l = l / w的水滴的元素(0.8,30)表明,液滴的速度大大都取决于l, l。Ca的依赖很强的λ> 1,而对于> 1来说，它不那么重要。
Droplet microfluidic techniques offer an attractive compromise between the throughput (of i.e. reactions per second) and the number of input/output controls needed to control them. Reduction of the number of controls follows from the confinement to essentially one-dimensional flow of slugs in channels which-in turn-relies heavily on the speed of flow of droplets. This speed is a complicated function of numerous parameters, including the volume of droplets (or length L of slugs), their viscosity mu(d), viscosity mu(c) and rate of flow of the continuous phase, interfacial tension and geometry of the cross-section of the channel. Systematic screens of the impact of these parameters on the speed of droplets remain an open challenge. Here we detail an automated system that screens the speeds of individual droplets at a rate of up to 2000 experiments per hour, with high precision and without human intervention. The results of measurements in channels of square cross-section (of width w = 360 mu m) for four different values of the contrast of viscosities lambda = mu(d)/mu(c) = 0.3, 1, 3, and 33, wide ranges of values of the capillary number Ca is an element of (10(-4), 10(-1)), and wide ranges of lengths of droplets l = L/w is an element of (0.8, 30) show that the speed of droplets depends significantly both on l and on l. The dependence on Ca is very strong for lambda > 1, while it is less important both for lambda > 1.