Niu Xize, Gulati Shelly, Edel Joshua B, deMello Andrew J
Department of Chemistry, Imperial College London, South Kensington, London, UKSW7 2AZ.
Lab Chip. 2008 Nov;8(11):1837-41. doi: 10.1039/b813325e. Epub 2008 Oct 8.
A novel method is presented for controllably merging aqueous microdroplets within segmented flow microfluidic devices. Our approach involves exploiting the difference in hydrodynamic resistance of the continuous phase and the surface tension of the discrete phase through the use of passive structures contained within a microfluidic channel. Rows of pillars separated by distances smaller than the representative droplet dimension are installed within the fluidic network and define passive merging elements or chambers. Initial experiments demonstrate that such a merging element can controllably adjust the distance between adjacent droplets. In a typical scenario, a droplet will enter the chamber, slow down and stop. It will wait and then merge with the succeeding droplets until the surface tension is overwhelmed by the hydraulic pressure. We show that such a merging process is independent of the inter-droplet separation but rather dependent on the droplet size. Moreover, the number of droplets that can be merged at any time is also dependent on the mass flow rate and volume ratio between the droplets and the merging chamber. Finally, we note that the merging of droplet interfaces occurs within both compressing and the decompressing regimes.
本文提出了一种在分段流微流控装置中可控合并水相微滴的新方法。我们的方法是通过利用微流控通道内的无源结构，利用连续相的流体动力阻力和离散相的表面张力之间的差异。在流体网络中安装间距小于代表性液滴尺寸的成排柱子，这些柱子定义了无源合并元件或腔室。初步实验表明，这种合并元件可以可控地调节相邻液滴之间的距离。在典型情况下，一个液滴会进入腔室，减速并停止。它会等待，然后与后续液滴合并，直到表面张力被液压克服。我们表明，这种合并过程与液滴间的间距无关，而是取决于液滴大小。此外，在任何时刻可合并的液滴数量也取决于质量流率以及液滴与合并腔室之间的体积比。最后，我们注意到液滴界面的合并发生在压缩和解压缩两种状态下。
