Generation of monodisperse particles by using microfluidics: Control over size, shape, and composition
Generation of monodisperse particles by using microfluidics: Control over size, shape, and composition
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DOI：
10.1002/anie.200462226
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发表时间：
2005-01-01
影响因子：
16.6
通讯作者：
Whitesides, GM
中科院分区：
文献类型：
--
作者：
Xu, SQ;Nie, ZH;Whitesides, GM
734 2005 Wiley-VCH Verlag GmbH & Co. KGaA，魏因海姆DOI：10.1002/ange. 200462226 Angew. 2005，117，734-738膜乳化[6]和多级方法。[7，8]这些方法中的大多数都是针对特定材料的。一种足够普遍的技术，可适用于一系列材料，并允许生产单分散胶体，控制大小和形状尚未得到证实，将是广泛有用的。我们使用了一种新型的微流体流动聚焦装置（MFFD）[11]，以产生不同大小和形状的液滴和窄分散性，这些液滴在原位固化。通过使用软光刻在聚（二甲基硅氧烷）或聚氨酯中制备MFFD;[9，10]适当选择制造材料使我们能够生产油包水或水包油分散体。我们的实验表明，在这些MFFD中的液体线程的稳定和可控的分裂背后的流体动力学机制在很大程度上是不敏感的分散相的组成。我们利用这一特性来生产金属颗粒，微凝胶和含有液晶，荧光染料和无机纳米颗粒的聚合物颗粒。还证明了对固化珠的形状和尺寸的控制;通过控制单个液滴的体积和微通道的横截面积来产生球体、圆盘、椭圆体和棒。图1a显示了MFFD的设计。沿装置长轴的压力梯度沿着迫使两种不混溶的液体通过MFFD的孔口。从装置的两侧供应连续相;从中心通道供应包含分散相的液体流（图1a）。连续相围绕内部不混溶液体，使得内螺纹变得不稳定并且以周期性方式在孔口中断裂，以将液滴释放到出口通道中。我们最近表明，气体的窄尺寸分布
734 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/ange. 200462226 Angew. Chem. 2005, 117, 734–738 membrane emulsification,[6] and multistage processes.[7, 8] Most of these methods are specific to a particular material. A technique sufficiently general to be applicable to a range of materials and allow the production of monodisperse colloids with control over size and shape has not been demonstrated and would be widely useful.We have used a new type of microfluidic flow-focusing device (MFFD)[11] to generate droplets of different sizes and shapes and narrow dispersity, and these droplets were solidified in situ. The MFFDs were prepared in either poly (dimethylsiloxane) or polyurethane by using soft lithography;[9, 10] an appropriate choice of the material of fabrication allowed us to produce water-in-oil or oil-in-water dispersions. Our experiments suggest that the hydrodynamic mechanism behind the stable and controllable breakup of liquid threads in these MFFDs is largely insensitive to the composition of the dispersed phase. We exploited this property to produce metal particles, microgels, and polymer particles that contain liquid crystals, fluorescent dyes, and inorganic nanoparticles. Control of both the shape and size of the solidified beads was also demonstrated; spheres, disks, ellipsoids, and rods were produced by controlling the volume of the individual drops and the cross-sectional area of the microchannel. Figure1a shows the design of the MFFD. A pressure gradient along the long axis of the device forced two immiscible liquids through the orifice of MFFD. The continuous phase was supplied from two sides of the device; the liquid stream comprising the dispersed phase was supplied from a central channel (Figure 1a). The continuous phase surrounds the inner, immiscible liquid so that the inner thread becomes unstable and breaks in the orifice in a periodic manner to release droplets into the outlet channel. We showed recently that the narrow size distribution of gaseous