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: 0701324
• 负责人: Sandra Troian
• 金额: $ 40万
• 依托单位: California Institute of Technology
• 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 2011-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0701324&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.

建议没有。项目编号：ctc -0625622主要研究者：SANDRA M. TROIANINSTITUTION: PRINCETON university这项资助建立在先前资助的研究基础上，在这些研究中，研究人员展示了在玻璃或硅基板上连续微尺度薄膜内的电子流动控制，该研究将基板图像化与电子可寻址微加热器阵列相结合，以产生热毛细应力。然而，在100 nl范围内动员和操纵离散液滴，需要更深入地了解热毛细力和毛细力的耦合、接触角滞后和钉住引起的液滴保留力、去除液滴进行运输所需的输入功率的比例、液滴在断裂和点胶的图形基板上破裂之前的薄膜破裂动力学，以及增溶表面活性剂对热毛细流动的影响。目前的研究将研究离散液滴在空间和时间上被热毛细应力调制的动态行为，在基材被划分为各种润湿和非润湿几何形状的情况下。除了影响气液界面的应力外，表面能和几何形状也会影响液体的构象和流动行为。基于激光干涉测量、全内反射荧光、椭偏和原子力显微镜的测量结果将与基于润滑理论的流体动力学模型预测结果直接进行比较。准确估计液滴脱落和分裂所需的输入功率将有助于开发更节能的设备。这些研究的结果将证明对依赖于电润湿和介电电泳的替代微流体系统是有用的，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、混合、分配和分析的自动化微流体系统正在迅速扩展诊断能力，其应用范围从基因组学和药物配方到空间旅行和生物防御应用的环境监测。这些技术的基础是在有纹理的表面上进行微流体动力学流动，以帮助液滴分配和分配到特定位置，液滴分裂和聚并，选择性液滴混合，以及沿着电子可编程路径传输。适当的功能依赖于可重复的制造和操作，以及流体动力学模型的流动优化。然而，这种开放式结构的设备还没有完全做好商业化的准备，部分原因是对液滴位错、断裂和动力学的理解有限。PI计划为(a)招收和留住女研究生(b)引导她们成功成为博士后研究学者或初级教师，实现多样化战略。这些努力是为了回应这样一个事实，即攻读工程科学高级研究的妇女人数没有按预期的速度增加（在某些领域甚至在减少）。作为这项研究的一部分，将发起一个系列讨论会，其中将深入讨论讨论这一问题的学术文章，以便查明和克服阻碍初级妇女在研究密集活动中取得进步的做法。