Droplet Manipulation by Thermocapillary Actuation for Microfluidic Applications

提案编号： CTS-0625622主要制造商：SANTORM。TROIANINSTITUTION： 普林斯顿大学微流体应用的热毛细驱动液滴操纵这项资助建立在以前资助的研究中，研究人员证明了在玻璃或硅衬底上的连续微尺度薄膜内的电子流量控制，通过衬底图案化与电子可寻址微加热器阵列的组合来产生热毛细应力。然而，100 nl范围内离散液滴的动员和操纵需要更深入地了解热毛细力和毛细力的耦合、接触角滞后和钉扎引起的液滴保持力、驱逐液滴进行传输所需的输入功率分数、膜的动力学在图案化基底上的液滴破裂之前破裂以进行切割和分配，以及增溶表面活性剂对热毛细流动的影响。目前的研究将探讨离散液滴的动态行为调制的空间和时间的热毛细应力在基板划分成各种润湿和非润湿的几何形状的存在下。除了影响气液界面的应力外，液体的形态和流动行为还受到表面能和几何形状的影响。 基于激光干涉测量，全内反射荧光，椭圆偏振和原子力显微镜的测量将直接与基于润滑理论的流体动力学模型的预测进行比较。对液滴脱钉和断裂所需的输入功率的准确估计将允许开发更节能的设备。这些研究的结果将被证明是有用的替代微流体系统依赖于电润湿和介电泳，其中类似的能力，液滴驱动正在研究由其他团体。用于液滴路由、混合、分配和分析的自动化微流体系统正在迅速扩大从基因组学和药物配制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。这些技术的基础涉及在纹理化表面存在下的微流体动力学流动，以帮助液滴分配和分配到特定位点、液滴断裂和聚结、选择性液滴的混合以及沿沿着电子可编程路径的输送。正确的功能依赖于可重复的制造和操作，再加上流体动力学模型，以优化流量。然而，这种开放式结构的器件还没有完全准备好商业化，部分原因是对液滴位错、断裂和动力学的理解有限。 PI计划采取多样化战略，以便（a）招聘和留住女研究生，（B）指导这些学生成功地担任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，即在工程科学领域攻读高级研究的妇女人数没有以预期的速度增长（在某些领域甚至有所下降）。作为这项研究的一部分，将举办一系列研讨会，深入讨论涉及这一问题的学术文章，以查明和克服阻碍年轻妇女在研究密集型活动中取得进步的做法。

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.