Xiao Ke, Wu Chen-Xu
Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, People's Republic of China and Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325016, People's Republic of China.
Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, People's Republic of China.
Phys Rev E. 2022 Jun;105(6-1):064609. doi: 10.1103/PhysRevE.105.064609.
Even though electrowetting-on-dielectric (EWOD) is a useful strategy in a wide array of biological and engineering processes with numerous droplet-manipulation applications, there is still a lack of complete theoretical interpretation on the dynamics of electrowetting. In this paper we present an effective theoretical model and use the Onsager variational principle to successfully derive general dynamic shape equations for electrowetting droplets in both the overdamped and underdamped regimes. It is found that the spreading and retraction dynamics of a droplet on EWOD substrates can be fairly well captured by our model, which agrees with previous experimental results very well in the overdamped regime. We also confirm that the transient dynamics of EW can be characterized by a timescale independent of liquid viscosity, droplet size, and applied voltage. Our model provides a complete fundamental explanation of EW-driven spreading dynamics, which is important for a wide range of applications, from self-cleaning to novel optical and digital microfluidic devices.
尽管介电电泳（EWOD）在众多具有大量液滴操纵应用的生物和工程过程中是一种有用的策略，但对于电润湿动力学仍缺乏完整的理论解释。在本文中，我们提出了一个有效的理论模型，并使用昂萨格变分原理成功推导出了过阻尼和欠阻尼状态下电润湿液滴的一般动态形状方程。结果发现，我们的模型能够很好地捕捉液滴在EWOD基板上的铺展和收缩动力学，在过阻尼状态下与先前的实验结果非常吻合。我们还证实，电润湿的瞬态动力学可以由一个与液体粘度、液滴大小和施加电压无关的时间尺度来表征。我们的模型为电润湿驱动的铺展动力学提供了完整的基本解释，这对于从自清洁到新型光学和数字微流控设备等广泛的应用都很重要。
