Materials World Network: Electric Field Induced Microfluidic Manipulation

该NSF材料世界网络奖支持德国戈廷根的马克斯·普朗克动力学和自组织研究所(MPI)与肯塔基州曼哈顿的堪萨斯州立大学之间的国际合作研究。这两个小组将合作研究地形结构微通道中微流体的静力学和动力学。随着芯片上的化学工厂、快速变焦距光学液体透镜和高能见度视速电子纸的出现，微流控技术在封闭通道中或衬底表面对微升或纳米升液体或液体溶液的可控操纵正变得越来越重要。这种液体操纵通常是通过使用电场来控制的，特别是通过电润湿效应来控制液滴在表面上的接触角。目前，人们还不清楚电场效应、润湿层、表面滑移、衬底表面形貌和液体形态不稳定性的相互作用如何控制液体在地形结构通道中的时间动力学。堪萨斯州将研究润湿层和表面滑移对平面的影响，以及电场和/或液体剪切的存在如何改变它们。对于足够大的电场，均匀的润湿层预计将经历电流体动力不稳定性(并分解成纳米液滴)，其中液体剪切的附加效应起着未知的作用。均匀的润湿层、表面纳米液滴或电场诱导的表面有序化将影响固/液界面的滑移行为。戈廷根的MPI小组将研究电润湿过程中表面形貌的相互作用，以及这种地形如何影响沿微流体通道传播的依赖时间的液丝，以及这些通道内从液丝到液滴的液体形态不稳定性。两个小组之间将有频繁的人员交流，因为润湿层和滑移的存在(在堪萨斯州研究)将在控制微流体通道中扩散和形态破裂的时间相关性方面发挥主要作用(在哥廷根研究)。这些交流将加强和增进两个团体之间的教育、文化和国际合作。拟议的研究将为更好地理解拓扑结构微流控装置中液体的静态和动态电操作提供基本基础。这些信息有望在微流控器件设计的许多不同领域中具有重要的实际用途。对应的项目由德国国家科学基金会(DFG)资助。

This NSF Materials World Network award supports international collaborative research between the Max Planck Institute (MPI) for Dynamics and Self-organization in Goettingen, Germany and Kansas State University in Manhattan, KS. The two groups will collaborate in studying the statics and dynamics of microfluidics in topographically structured microchannels. Microfluidics, the controlled manipulation of microliters or nanoliters of liquid or liquid solution in closed channels or on a substrate surface is gaining increasing technological importance with the creation of chemical factories on a chip, fast variable focal length optical liquid lenses and high visibility video speed electronic paper. This liquid manipulation is frequently controlled via the use of electric fields and in particular via the electrowetting effect, which controls the contact angle of droplets on surfaces. Currently it is not well understood how the interplay of electric field effects, wetting layers, surface slip, surface topography of the substrate and liquid morphological instabilities combine to govern the time dynamics of liquids in topographically structured channels. The influence of wetting layers and surface slip on planar surfaces and how they are changed by the presence of an electric field and/or liquid shear will be studied in Kansas. Uniform wetting layers are predicted to undergo an electrohydrodynamic instability (and break up into nanodroplets) for sufficiently large electric fields where the additional effects of liquid shear play an unknown role. Uniform wetting layers, surface nanodroplets or electric field induced surface ordering is expected to influence the slip behavior found at solid/liquid interfaces. The MPI group in Goettingen will study the interplay of surface topography during electrowetting and how this topography influences the time dependent liquid filament spreading down microfluidic channels, as well as, liquid morphological instabilities from liquid filaments to liquid droplets within these channels. There will be frequent exchanges of personnel between the two groups because the presence of wetting layers and slip (studied in Kansas) will play a major role in governing the time dependence of both the spreading and morphological break up in microfluidic channels (studied in Goettingen). These exchanges will strengthen and enhance the educational, cultural and international cooperation between the two groups. The proposed research will provide the fundamental foundations for a better understanding of the static and dynamic electrical manipulation of liquids in topographically structured microfluidic devices. This information is expected to be of significant practical use for many different fields in microfluidic device design. The counterpart project is funded by the German National Science Foundation (DFG).