Anisotropic Liquid Dielectrophoresis and Interfacial Forces

在技术驱动下，人们对利用外部影响来移动或塑造少量液体的兴趣与日俱增，这一过程被称为“微流控”。使用电力而不是机械力来实现这种驱动是方便的，因为这涉及到相对简单的设备架构，不包含任何移动部件。现有的由电压驱动的非机械微流控技术包括电润湿，它只适用于导电液体，以及介电泳法，它既适用于导电液体，也适用于非导电液体。我们以前已经展示了如何使用非导电各向同性液体中的介电泳力不仅可以产生强制润湿和液体扩散，还可以产生液膜皱折，在液膜的液-气界面上，工程电场分布会将其自身的复制品印记为扭曲图案。在这项建议中，将研究液体介电泳能在纯各向异性液体(即向列型液晶而不是简单的各向同性液体)中产生附加功能和更好的控制的可能性。在纯各向异性液体中的液体介电以前还没有被研究过，无论是实验上还是理论上。我们提出的综合协作实验和理论研究方法旨在理解和利用当自由和受限各向异性液体受到电场作用时，可以在自由和受限各向异性液体内部和表面产生的力。这项拟议的研究将探索一种令人兴奋的新可能性，即使用各向异性液体以及特殊的限制几何结构，即使在简化的电极结构下，也可以产生电压控制驱动的微流控泵。我们的行业支持者包括世界领先的液晶和活性介元研究、开发和制造商默克化工有限公司，以及正在开发基于液晶和微流控效应的下一代信息显示器的惠普和ADT。

There is a growing technology-driven interest in using external influences to move or shape small quantities of liquids, a process that is referred to as "microfluidic actuation". Using electrical, rather than mechanical, forces to achieve this actuation is convenient because this involves relatively simple device architectures that contain no moving parts. Existing non-mechanical microfluidic actuation techniques that are driven by the application of a voltage include electrowetting, which only works with conducting liquids, and dielectrophoresis, which works with both conducting and non-conducting liquids. We have previously shown how dielectrophoresis forces in non-conducting isotropic liquids can be used to create not only forced wetting and liquid spreading, but also liquid film wrinkling in which an engineered electric field distribution imprints a replica of itself as a distortion pattern at the liquid-air interface of the film. In this proposal the possibility that liquid dielectrophoresis can lead to added functionality and greater control within a pure anisotropic liquid, i.e. a nematic liquid crystal rather than a simple isotropic liquid, will be investigated. Liquid dielectrophoresis in pure anisotropic liquids has not been studied before, either experimentally or theoretically. Our proposed integrated collaborative experimental and theoretical research approach aims to understand and exploit the forces that can be created within, and at the surface of, free and confined anisotropic liquids when they are subject to electric fields. The proposed research will investigate an exciting new possibility of using anisotropic liquids along with particular confinement geometries which allow voltage controlled actuated microfluidic pumping to be produced even with simplified electrode architectures. Our industrial supporters include Merck Chemicals Ltd, the world-leading researcher, developer and manufacturer of liquid crystals and reactive mesogens, together with Hewlett-Packard and ADT, who are developing the next generation of information displays based on liquid crystal and microfluidic effects.