Collaborative Research: Probing the hydrodynamic resistance and traffic of confined droplets in microfluidic networks for the rational design of two-phase fluidic processors

Texas Tech University, Lubbock TX

Investigators

Abstract

0932796/0933090 Vanapalli/Wong The notion of using tiny nanoliter-scale water droplets in an oil phase as reaction vessels for applications in chemical and life sciences is turning into a reality due to rapid progress in the science and engineering of microfluidics. Despite such progress, fundamental challenges remain to transform current droplet-based devices to next generation fluidic processors capable of characterizing large-scale biological complexity. Two scientific challenges exist in the realization of such an integrated two-phase fluidic processor. First, the transport of a large number of confined droplets in microchannels leads to prohibitively excess pressure drop. Second, due to collective hydrodynamic resistive effects, it is difficult to control the position and timing of droplets for reactions on a device. To address these challenges requires a thorough understanding of hydrodynamic resistance introduced by the motion of confined droplets. The PIs will combine experiments and modeling to quantify the hydrodynamic resistance due to a confined droplet and its dependence on system parameters. Novel aspects of the work include the use of a sensitive microfluidic comparator technique to measure hydrodynamic resistance at the level of individual droplets. Experimental methods and models will be developed to quantify the currently unknown contribution of end-cap, thin film and corner flows to the hydrodynamic resistance of a droplet in rectangular microchannels, with the ultimate goal of achieving predictive capability of pressure drop for enhanced device performance. This study will enable rational design of two-phase fluidic processors that could be potentially autonomous and passively driven. This work will also impact other engineering areas that rely on fundamental understanding of multiphase flows in confined media such as tertiary oil recovery and fuel cells. Educational component of the project includes drawing minority graduate and undergraduate students to the visually striking research on microfluidics and providing state-of-the-art training in microfluidics, microfabrication, microscopy and numerical modeling. The PIs will pursue outreach activities at their respective institutions such as developing a weeklong hands-on-activities and lectures on the theme "Bubbles on Chips".