CAREER:Collective hydrodynamics of confined drops in microfluidic parking networks

职业：微流体停车网络中受限液滴的集体流体动力学

• 批准号: 1150836
• 负责人: Siva Vanapalli
• 金额: $ 40万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1150836&HistoricalAwards=false
• 关键词: CAREER; Collective; hydrodynamics; confined; drops

1150836PI: VanapalliCurrent high-throughput screening (HTS) methods use robotic actuators for dispensing and diluting fluids in microliter-scale multi-well plates. This approach requires significant investment and imposes constraints on reducing the fluid volumes due to evaporation. Microfluidic arrays of immobilized drops could emerge as an inexpensive and powerful alternative to multi-well plate screening. However, the technical challenge in generating these static drop arrays (SDAs) is to develop a means to (i) array drops of tunable volume and (ii) vary the reagent concentration from drop to drop in the array. Despite recent progress, current microfluidic devices are incapable of manipulating individual drop concentration and varying the volume in the static array. The field is ripe for breakthroughs and if the challenge is met the benefits are enormous ? low cost; reduced fluid volumes; capability to monitor many reactions in drops simultaneously; and ability to further manipulate drops as the position is indexed in the array.To address this challenge, the PI proposes to investigate the dynamics of trains of confined drops and/or long plugs in a special class of fluidic networks called microfluidic parking networks (MPNs). MPNs typically consist of a repeated sequence of loops, with each loop containing a fluidic trap to park (i.e. immobilize) drops. Preliminary exploration in just a small region of the control parameter space yielded a series of unanticipated and astonishing behaviors driven by collective hydrodynamic resistive interactions in the network. Sub-classes of collective behavior involving drop parking, break-up, and coalescence led to the generation of SDAs with tuneable volumes as well as with variation in reagent concentration from drop-to-drop. To harness the full potential and autonomous control offered by the preliminary observations, the PI proposes a comprehensive investigation of the collective hydrodynamics of drops in MPNs, than is currently available. The investigation will focus on (i) coordinated experimental and modeling efforts to predict the spatiotemporal dynamics of drops in MPNs that drive many of the collective behaviors we observed. New tools involving drop-on-demand generators will be integrated into MPNs, to vary the control parameters to map the full phase space of collective dynamics (ii) providing a complete picture of drop/plug break-up in MPNs, by characterizing the fragmentation dynamics to control the size of drop relative to trap. This data when combined with a novel strategy to measure pressure variations during break-up will enable rigorous confrontation of existing models of drop break-up at bifurcations; and (iii) controlling the coalescence and material exchange between parked and moving drops, by probing the factors that regulate film drainage, and passive tracer transport and mixing when drops fuse. The proposed fundamental investigations will enable the development of inexpensive SDAs with sophisticated capabilities. This work is poised to deliver a true nanoliter-scale analog of the multi-well plate with the enormous simplification that dilutions and mixing are carried out passively, thus solving a long-standing challenge. Replacing a room full of robots with these penny-sized devices will tremendously benefit HTS methods in biology and material science. The CAREER project will also provide interdisciplinary training for students in the cutting-edge areas of microfluidics, multiphase flows, microfabrication and nonlinear dynamics. Graphic modules of droplet traffic and parking will be developed for active learning, where students will design their own network topologies and conduct original analysis. These modules will be integrated into an elective course on microfluidics and the core courses. Outreach activities will be developed for middle school girls on the theme "Bubbles on Chips" in which students will mold devices containing a street map of Lubbock and study bubble traffic to identify the exits that bubbles choose.

1150836PI：Vanapallicurrent高通量筛选（HTS）方法使用机器人执行器来分配和稀释微尺度多孔板中的流体。这种方法需要大量的投资，并在减少由于蒸发引起的流体量而施加限制。固定液滴的微流体阵列可以作为多孔板筛选的廉价且有力的替代品。但是，生成这些静态下降阵列（SDA）的技术挑战是为（i）（i）可调音量阵列的阵列和（ii）改变试剂浓度从阵列中的下降到滴度。尽管最近进展，但当前的微流体设备仍无法操纵单个液滴浓度并改变静态阵列中的体积。该领域的突破已经成熟，如果应对挑战，那么巨大的收益是巨大的吗？低成本;流体量减少；能够同时监测滴剂中的许多反应；以及在数组中索引的位置时进一步操纵下降的能力。为了应对这一挑战，PI建议在特殊类别的流体网络中调查被约束滴滴和/或长插头的动态，称为微流体停车网络（MPNS） ）。 MPN通常由重复的环序列组成，每个环中包含一个流体陷阱到停放（即固定）滴。在控制参数空间的一小部分中，初步探索产生了一系列意外的和惊人的行为，该行为是由网络中集体流体动力的相互作用驱动的。集体行为的子类涉及停车，分手和合并的子类，导致SDA产生具有可调量的SDA，以及从液滴到滴剂的试剂浓度变化。为了利用初步观察提供的全部潜力和自主控制，PI提出了对MPN中滴滴的集体水动力学的全面调查，这比目前可用。该研究将集中于（i）协调的实验和建模工作，以预测MPN中滴落的时空动力学，这些动力学推动了我们观察到的许多集体行为。涉及下降生成器的新工具将集成到MPN中，以更改控制参数，以映射集体动力学的整个相位空间（II），通过表征片段来表征MPN中滴/插头分解的完整图片动力学以控制相对于陷阱的滴大小。当这些数据与分解过程中衡量压力变化的新策略结合使用时，将使现有的分叉中现有模型分解模型进行严格的对抗； （iii）通过探测调节薄膜引流的因素以及在液滴保险丝时，控制停放和移动液滴之间的合并和材料交换。拟议的基本调查将使具有复杂能力的廉价SDA开发。这项工作有望在多孔板上提供真正的纳米尺度类似物，并进行了巨大的简化，即稀释和混合是被动地进行的，从而解决了长期的挑战。用这些便士大小的设备代替一个装满机器人的房间将极大地使生物学和材料科学中的HTS方法受益。职业项目还将为微流体，多相流，微型制造和非线性动态的尖端领域的学生提供跨学科培训。液滴流量和停车位的图形模块将用于积极学习，学生将设计自己的网络拓扑并进行原始分析。这些模块将集成到有关微流体和核心课程的选修课程中。将为中学女孩开发外展活动，主题为“芯片上的气泡”，其中学生将塑造包含Lubbock街道地图的设备，并研究泡泡流量，以识别泡沫选择的出口。