Hao Shaoqian, Xie Zhang, Li Zheng, Kou Jianlong, Wu Fengmin
Institute of Theoretical Physics, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Shanxi University, Taiyuan 030006, China.
Department of Physics, Zhejiang Normal University, Jinhua 321004, China.
Nanoscale. 2021 Oct 1;13(37):15963-15972. doi: 10.1039/d1nr03467g.
The transport direction of water droplets on a functionalized surface is of great significance due to its wide applications in microfluidics technology. The prevailing view is that a water droplet on a wedge-shaped groove always moves towards the wider end. In this paper, however, molecular dynamics simulations show that a water droplet can move towards the narrower end if placed at specific positions. It is found that the direction of water droplet transport on a grooved surface is related to its initial position. The water droplet moves towards the wider end only when it is placed near the wider end initially. If the water droplet is placed near the narrower end, it will move in the opposite direction. The novel phenomenon is attributed to the opposite interactions of the groove substrate and the groove upper layers with water droplets. Two effective models are proposed to exploit the physical origin of different transport directions of water droplets on a wedge-shaped groove surface. The study provides an insight into the design of nanostructured surfaces to effectively control the droplet motion.
由于水滴在功能化表面上的传输方向在微流控技术中有广泛应用，因此具有重要意义。普遍观点认为，楔形凹槽上的水滴总是朝着较宽的一端移动。然而，本文通过分子动力学模拟表明，如果将水滴放置在特定位置，它可以朝着较窄的一端移动。研究发现，带凹槽表面上水滴的传输方向与其初始位置有关。只有当水滴最初放置在较宽一端附近时，它才会朝着较宽的一端移动。如果水滴放置在较窄一端附近，它将向相反方向移动。这种新现象归因于凹槽基底和凹槽上层与水滴的相反相互作用。提出了两个有效模型来探究楔形凹槽表面上水滴不同传输方向的物理根源。该研究为有效控制液滴运动的纳米结构表面设计提供了思路。
