Experimental Interface Physics, Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
Experimental Interface Physics, Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
Adv Colloid Interface Sci. 2014 Aug;210:2-12. doi: 10.1016/j.cis.2013.09.007. Epub 2013 Oct 10.
More than one century ago, Lippmann found that capillary forces can be effectively controlled by external electrostatic forces. As a simple example, by applying a voltage between a conducting liquid droplet and the surface it is sitting on we are able to adjust the wetting angle of the drop. Since Lippmann's findings, electrocapillary phenomena - or electrowetting - have developed into a series of tools for manipulating microdroplets on solid surfaces, or small amounts of liquids in capillaries for microfluidic applications. In this article, we briefly review some recent progress of fundamental understanding of electrowetting and address some still unsolved issues. Specifically, we focus on static and dynamic electrowetting. In static electrowetting, we discuss some basic phenomena found in DC and AC electrowetting, and some theories about the origin of contact angle saturation. In dynamic electrowetting, we introduce some studies about this rather recent area. At last, we address some other capillary phenomena governed by electrostatics and we give an outlook that might stimulate further investigations on electrowetting.
一个多世纪以前， Lippmann 发现毛细作用力可以通过外部静电力有效地控制。作为一个简单的例子，通过在一个导电液滴和它所接触的表面之间施加电压，我们能够调节液滴的润湿角。自 Lippmann 的发现以来，电毛细现象（或电润湿）已经发展成为一系列在固体表面上操纵微液滴或在毛细管中操纵少量液体的工具，用于微流控应用。在本文中，我们简要回顾了电润湿的一些基础理解的最新进展，并讨论了一些尚未解决的问题。具体来说，我们专注于静态和动态电润湿。在静态电润湿中，我们讨论了直流和交流电润湿中发现的一些基本现象，以及关于接触角饱和起源的一些理论。在动态电润湿中，我们介绍了这个相对较新的领域的一些研究。最后，我们讨论了一些由静电控制的其他毛细现象，并给出了一个可能会激发对电润湿进一步研究的展望。
