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

0932796/0933090 Vanapalli/Wong由于微流体科学和工程的快速发展，在化学和生命科学中使用油相中的微小纳升级水滴作为反应容器的概念正在成为现实。尽管取得了这样的进展，但将当前基于液滴的设备转变为能够表征大规模生物复杂性的下一代流体处理器仍然存在根本挑战。在实现这样的集成两相流体处理器中存在两个科学挑战。首先，在微通道中输送大量受限液滴导致过高的压降。其次，由于集体流体动力学阻力效应，难以控制液滴在装置上反应的位置和时间。为了解决这些挑战，需要彻底了解由受限液滴的运动引入的流体动力学阻力。PI将结合联合收割机实验和建模，以量化由于受限液滴及其对系统参数的依赖性而产生的流体动力学阻力。新的方面的工作包括使用一个敏感的微流体比较器技术来测量流体动力学阻力的水平，个别液滴。将开发实验方法和模型，以量化目前未知的贡献端盖，薄膜和角落流的流体动力学阻力的液滴在矩形微通道，最终目标是实现预测能力的压降，以提高设备的性能。这项研究将使合理设计的两相流体处理器，可能是潜在的自主和被动驱动。这项工作也将影响其他工程领域，这些领域依赖于对封闭介质中多相流的基本理解，如三次采油和燃料电池。该项目的教育部分包括吸引少数民族研究生和本科生对微流体进行视觉上引人注目的研究，并提供微流体，微加工，显微镜和数值建模方面的最先进培训。PI将在各自的机构开展外联活动，例如开展为期一周的实践活动和主题为“芯片上的气泡”的讲座。

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".