微流控芯片中多支路交汇结构处微液滴流动特性与捕获机理研究

在微流控芯片中实现对液滴在交汇结构处流动的精确控制，可以提高具有捕获功能的芯片的可靠性，避免发生不利于应用效果的液滴合并、破碎或者流动路径偏离等现象。目前，微液滴流动控制较多依赖于电、热、电磁等外加作用场，依靠流动本身来实现的微液滴操控效率和准确性不高，并且对影响微液滴自身流动特性的机理分析不够深入。本项目将实验、数值和理论研究微流控芯片中多支路交汇结构处的液滴内外流场拓扑结构、液滴界面变形及液滴整体流动行为，分析影响液滴支路选择、停留或融合等行为的主要因素，揭示液滴合并机理，实现对液滴在交汇结构处流动的精确控制。考虑多液滴在流场中的耦合作用，设计具有集成多支路交汇结构的高效捕获液滴的微流控芯片，在微通道内实现液滴的位置调整、流速改变、流动时的支路选择、碰撞与融合等效果，建立芯片内液滴捕获效率的评价方法。研究结果将丰富微液滴控制的流体力学基础，提高微流控芯片的稳定性、精确性及可操作性。

The accurate control of the micro-droplet flow with multiple-branch junction will improve the reliability of the micro-fluidic chip by avoiding the negative effects, such as droplets fusion, droplet breakup and branch deviation, in the application of the chip. The efficiency and the accuracy are low for the manipulating of the droplet except using the extra electric, thermal or electromagnetic device as well as the mechanism of the droplet flow is not clear. This project will investigate the velocity field inside/outside of the micro-droplet, variation of the droplet surface and flow behaviors of the droplet in the multiple-branch junction by experiments, numerical simulation and theoretical analysis, to figure out the key factors affecting droplet branch-selecting, trapping and fusion so as to achieve the effective control of the micro-droplet in the junction. Moreover, introducing the coupling effects of the multiple-droplet, the evaluation method of the droplet trapping effectiveness in the chip will be achieved and the high-efficiency droplet trapping chip will be designed, which includes the droplet behaviors of velocity varying, branch-selecting, droplet collision and fusion. This research will enrich the foundation of micro-fluidics and improve the reliability, accuracy and operability of the micro-fluidic chip.