CAREER: Inertial Two-Phase Gas-Liquid Droplet Microflows

该项目旨在从根本上了解惯性两相气液液滴微流背后的控制物理，目的是开发能够同时实现微秒处理时间和数十mL/min吞吐量的新型微流体系统。该项目的变革方面在于为高速惯性微流体和液滴微流动的新兴领域提供新的见解。这种理解将导致下一代芯片实验室（LOC）和微总体分析系统（mTAS）的发展，其处理速度和吞吐量能力是前所未有的。该研究旨在解决(1)惯性、粘性和表面张力在液滴分离机制中的作用和相互作用，(2)绘制导致液滴产生的不同流动形式和转变，以及(3)受限微通道环境中惯性液滴碰撞混合的动力学。为了实现这些目标，研究工作将重点放在通过使用新的光学诊断技术对快速液滴动力学和相互作用的实验研究上。具体而言，微流体液滴生成平台可以控制和监测液体和气体的流动条件，将与高速显微镜系统相结合，研究液滴夹带动力学。类似地，微流控液滴对碰撞平台将与高速epi-荧光显微镜系统耦合，其中微分双荧光测量和mPIV将用作揭示与惯性碰撞混合相关的快速动力学的工具。实验工作将辅以一阶模型和不同现象的整体力分析。该项目的智力价值包括阐明惯性效应在受限气体载体微流中液滴分离、夹带和碰撞混合中的作用。本研究中所进行的测试结构和实验将为不同流动和边界条件对液滴形成和碰撞合并的影响提供独特的见解。所使用的微流体测试样品经过设计和制造，可以仔细控制液滴相互作用的几何形状和流动条件，从而更清楚地了解不同微观几何参数对夹带和碰撞聚结过程的影响。这项工作的研究努力和成果将整合到教育和推广活动中，向未被充分代表的本科工程和高中学生介绍微尺度流动和运输领域。在提供研究培训的同时，将引入创新的多层、自我可持续的课程，以发展教学内容。个别学生的研究训练将通过暑期实习计划进行，旨在开发微流体和光学诊断实验室模块和演示。这些将分别在一个本科实验班和几个拓展项目中部署和引入。

1151091HidrovoThis project aims to fundamentally understand the governing physics behind inertial two-phase gas-liquid droplet microflows, with the objective of developing novel microfluidic systems capable of microsecond processing times and tens of mL/min throughputs, simultaneously. The transformative aspect of the project resides in providing new insights into the emerging field of high speed inertial microfluidics and droplet microflows in specific. This understanding will lead to the development of next generation Lab-on-a-Chip (LOC) and micro-Total Analysis Systems (mTAS) with processing speed and throughput capabilities not seen before.The research aims to address (1) the role and interplay between inertial, viscous and surface tension forces in the droplet detachment mechanism, (2) mapping of the different flow regimes and transitions that can lead to droplet generation, and (3) the dynamics of inertial droplet collision mixing in a confined microchannel environment. Towards these goals, research efforts will be put forward that focus on the experimental study of the fast droplet dynamics and interactions through the use of novel optical diagnostics techniques. In specific, a microfluidic droplet generation platform that allows control and monitoring of the liquid and gas flows conditions will be coupled to a high speed microscopy system to study the liquid droplet entrainment dynamics. Similarly, a microfluidic droplet pair collision platform will be coupled to a high speed epi-fluorescence microscopy system, where differential dual fluorescence measurements and mPIV will be used as tools to unravel the fast dynamics associated with inertial collision mixing. The experimental work will be complemented by first order modeling and global force analysis of the different phenomena.The intellectual merit of the project includes elucidating the role of inertial effects in the detachment, entrainment and collision mixing of liquid droplets in confined gas carrier microflows. The test structures and experiments to be carried out in this study will provide unique insight into the effects that different flow and boundary conditions have on droplet formation and collision coalescence. The microfluidic test samples to be used are designed and fabricated so that the geometry and flow conditions under which the droplets interact can be carefully controlled, allowing for a clearer understanding of the effects that different microscopic geometrical parameters have on the entrainment and collision coalescence processes.The research endeavors and outcomes from this work will be integrated into educational and outreach activities that will introduce the field of microscale flow and transport to underrepresented undergraduate engineering and high school students early in their career. Innovative multilayer, self-sustainable programs geared towards development of teaching content while providing research training, will be introduced. Research training of individual students will take place through summer internship programs aimed at developing microfluidic and optical diagnostics lab modules and demonstrations. These will in turn be deployed and introduced in an undergraduate experimental class and several outreach programs, respectively.