Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Lab Chip. 2014 Feb 7;14(3):509-13. doi: 10.1039/c3lc51214b.
Coalescence of two kinds of pre-processed droplets is necessary to perform chemical and biological assays in droplet-based microfluidics. However, a robust technique to accomplish this does not exist. Here we present a microfluidic device to synchronize the reinjection of two different kinds of droplets and coalesce them, using hydrostatic pressure in conjunction with a conventional syringe pump. We use a device consisting of two opposing T-junctions for reinjecting two kinds of droplets and control the flows of the droplets by applying gravity-driven hydrostatic pressure. The hydrostatic-pressure operation facilitates balancing the droplet reinjection rates and allows us to synchronize the reinjection. Furthermore, we present a simple but robust module to coalesce two droplets that sequentially come into the module, regardless of their arrival times. These re-injection and coalescence techniques might be used in lab-on-chip applications requiring droplets with controlled numbers of solid materials, which can be made by coalescing two pre-processed droplets that are formed and sorted in devices.
在基于液滴的微流控中进行化学和生物分析，需要将两种预处理的液滴合并。然而，目前还没有一种可靠的技术可以实现这一点。在这里，我们提出了一种使用静水压结合传统注射器泵来同步重新注入两种不同液滴并将它们合并的微流控装置。我们使用由两个相对的 T 形接头组成的装置来重新注入两种液滴，并通过施加重力驱动的静水压来控制液滴的流动。静水压操作有助于平衡液滴的再注入速率，并允许我们对其进行同步。此外，我们还提出了一种简单但强大的模块，用于合并两个连续进入模块的液滴，而无需考虑它们的到达时间。这些重新注入和合并技术可能会用于需要具有受控数量固体材料的微流控芯片应用中，这些固体材料可以通过合并在设备中形成和分类的两种预处理液滴来实现。
