CAREER: Interrogating and Exploiting the Hydrodynamics of Concentrated Emulsions for Droplet Microfluidics

CBET-1454542PI：Sindy Tang，斯坦福大学这个职业项目研究的是微通道流动中浓缩乳状液的流体动力学。通常在这些流动中，液滴变得紧密堆积，它们可以相互结合或分离。在微流控系统的许多应用中，液滴中含有化学试剂或生物样品，通过微流控装置跟踪液滴的个体运动势在必行。如果水滴重新排列顺序或破裂，追踪它们就变得不可能了。该项目将确定液滴保持其相对空间排列的流型，即使当液滴通过包含其横截面形状变化的微通道时也是如此。该项目的结果将对为工程、生物科学和医学中的各种应用设计微流控系统的从业者有用。此外，这项研究的结果将用于为工科本科生开发一门新课程，以及为K-12学生开发演示模块和视频演示。该项目将研究浓缩乳状液在具有约束几何的微通道中的运动。初步结果表明，当流动方向改变时，流经包含收缩的通道的液滴的空间排列是完全可逆的，而另一种流态会导致液滴的随机破裂。该提案的目标是对这些体系进行参数描述，确定液滴破碎的原因，并为需要液滴通过微流控设备的设备生成设计规则，以保持液滴通过整个设备的顺序。

CBET - 1454542PI: Sindy Tang, Stanford UniversityThis CAREER project addresses the hydrodynamics of concentrated emulsions in microchannel flows. Typically in these flows, the droplets become closely packed, and they can coalesce with each other or break apart. In many applications of microfluidic systems, the drops contain chemical reagents or biological samples, and it is imperative to track the individual motion of drops through the microfluidic device. If the drops rearrange their order or breakup, tracking them becomes impossible. This project will identify flow regimes in which drops retain their relative spatial arrangements even when the flow takes the drops through microchannels that contain changes in their cross-sectional shapes. The results of the project will be useful to practitioners who design microfluidic systems for a variety of applications in engineering, biological sciences, and medicine. In addition, results from the research will be used in the development of a new course for engineering undergraduates as well as in the development of demonstration modules and video presentations for K-12 students.The project will examine the motion of concentrated emulsions in flow through microchannels with confining geometries. Preliminary results demonstrate an interesting flow regime where the spatial arrangement of drops that move through a channel containing a contraction is exactly reversible when the direction of the flow is changed and another regime that results in a stochastic breakup of drops. The goals of the proposal are to characterize these regimes parametrically, identify the cause of drop breakup, and to generate design rules for devices that require drops to move through microfluidic devices maintaining precisely the sequential order of drops through the entire device.