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

Stanford University, Stanford CA

Investigators

Abstract

CBET - 1454542 PI: Sindy Tang, Stanford University This 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.