Droplet Manipulation by Thermocapillary Actuation for Microfluidic Applications

通过热毛细管驱动进行液滴操纵，用于微流体应用

• 批准号: 0625622
• 负责人: Sandra Troian
• 金额: $ 40万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-10-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0625622&HistoricalAwards=false
• 关键词: Droplet; Manipulation; Thermocapillary; Actuation; Microfluidic

PROPOSAL NO.: CTS-0625622PRINCIPAL INVESTIGATOR: SANDRA M. TROIANINSTITUTION: PRINCETON UNIVERSITYDroplet Manipulation by Thermocapillary Actuation for Microfluidic Applications This grant builds upon previously funded studies in which the investigators demonstrated electronic flow control within continuous microscale films on glass or silicon substrates by a combination of substrate patterning with electronically addressable microheater arrays for generation of thermocapillary stresses. Mobilization and manipulation of discrete droplets in the 100 nl range, however, requires deeper insight into the coupling of thermocapillary and capillary forces, droplet retentive forces caused by contact angle hysteresis and pinning, the fraction of input power needed to dislodge droplets for transport, the dynamics of film rupture preceding droplet breakup on patterned substrates for scission and dispensing, and the effects of solubilized surfactants on thermocapillary flows. This current study will examine the dynamic behavior of discrete droplets modulated in space and time by thermocapillary stresses in the presence of substrates partitioned into various wetting and non-wetting geometries. Besides the stresses affecting the air-liquid interface, the liquid conformation and flow behavior are affected by surface energy and geometry. Measurements based on laser interferometry, total internal reflection fluorescence, ellipsometry and atomic force microscopy will be compared directly with predictions of hydrodynamic models based on lubrication theory. Accurate estimates of the input power required for droplet depinning and scission will allow development of more energy efficient devices. The results of these studies will prove useful to alternative microfluidic systems reliant on electrowetting and dielectrophoresis where similar capabilities for droplet actuation are being investigated by other groups. Automated microfluidic systems for droplet routing, mixing, dispensing and analysis are rapidly expanding diagnostic capabilities in fields as far ranging as genomics and drug formulation to environmental monitoring for space travel and biodefense applications. The cornerstone of these technologies involves micro-hydrodynamic flows in the presence of textured surfaces to assist in droplet dispensation and apportionment to specific sites, droplet scission and coalescence, mixing of selective droplets, and transport along electronically programmable pathways. Proper functioning relies on reproducible fabrication and operation coupled with hydrodynamic models for flow optimization. Such open architecture devices are not quite ready for commercialization, however, in part because of the limited understanding involving droplet dislocation, scission and dynamics. The PI plans to diversify strategies for (a) recruiting and retaining female graduate students and (b) guiding these students toward successful positions as postdoctoral research scholars or junior faculty. These efforts are in response to the fact that the number of women pursuing advanced study in the engineering sciences is not increasing at the expected rate (and in some fields even decreasing). As part of this study, a seminar series will be launched in which scholarly articles which speak to this problem will be discussed in depth in order to identify and overcome practices which retard the advancement of junior women in research intensive activities.

建议编号：CTS-0625622 PRINCIPAL调查员：Sandra M.TROIANINSTUTION：普林斯顿UNIVERSITYDroplet Actuation for Micro流体应用这笔赠款建立在之前资助的研究的基础上，在这些研究中，研究人员展示了通过衬底图案化和用于产生热毛细应力的电子可寻址微加热器阵列的组合，在玻璃或硅衬底上连续的微尺度薄膜内的电子流动控制。然而，在100nL范围内动员和操纵离散液滴，需要更深入地了解热毛细管力和毛细管力的耦合，接触角滞后和钉扎引起的液滴保持力，排出液滴进行传输所需的输入功率比例，用于切割和分配的图案化衬底上液滴破裂之前的膜破裂动力学，以及增溶的表面活性剂对热毛细管流的影响。这项当前的研究将研究离散液滴在空间和时间上受热毛细管应力调制的动态行为，这些液滴存在于被划分为各种润湿和非润湿几何形状的衬底中。除了影响气液界面的应力外，液体的构象和流动行为还受到表面能和几何形状的影响。基于激光干涉法、全内反射荧光法、椭偏法和原子力显微镜的测量结果将直接与基于润滑理论的流体力学模型的预测进行比较。准确估计液滴脱钉和断裂所需的输入功率将有助于开发更节能的设备。这些研究的结果将被证明对依赖于电润湿和介电的替代微流控系统是有用的，在这些系统中，其他小组正在研究类似的液滴驱动能力。用于液滴路径选择、混合、分配和分析的自动化微流控系统正在迅速扩大从基因组学和药物配方到太空旅行和生物防御应用的环境监测等领域的诊断能力。这些技术的基石涉及在有纹理的表面存在的微流体动力流动，以帮助液滴分配和分配到特定地点，液滴断裂和合并，选择性液滴的混合，以及沿电子可编程路径的传输。正确的运行依赖于可重复的制造和操作，以及用于流动优化的流体动力学模型。然而，这种开放结构的设备还没有完全准备好商业化，部分原因是对液滴位错、断裂和动力学的了解有限。PI计划使战略多样化，以(A)招聘和留住女研究生，以及(B)引导这些学生成为成功的博士后研究学者或初级教员。这些努力是为了应对这样一个事实，即在工程科学领域深造的妇女人数没有以预期的速度增加(在某些领域甚至还在减少)。作为这项研究的一部分，将举办一系列研讨会，深入讨论有关这一问题的学术文章，以找出和克服阻碍初级妇女参加密集研究活动的做法。