Wang Lei, Li Jing, Zhang Bo, Feng Shile, Zhang Mei, Wu Dong, Lu Yang, Kai Ji Jung, Liu Jing, Wang Zuankai, Jiang Lei
Beijing Key Lab of Cryo-Biomedical Engineering and Key Lab of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China.
Research (Wash D C). 2020 Aug 19;2020:6472313. doi: 10.34133/2020/6472313. eCollection 2020.
Achieving the directional and long-range droplet transport on solid surfaces is widely preferred for many practical applications but has proven to be challenging. Particularly, directionality and transport distance of droplets on hydrophobic surfaces are mutually exclusive. Here, we report that drain fly, a ubiquitous insect maintaining nonwetting property even in very high humidity, develops a unique ballistic droplet transport mechanism to meet these demanding challenges. The drain fly serves as a flexible rectifier to allow for a directional and long-range propagation as well as self-removal of a droplet, thus suppressing unwanted liquid flooding. Further investigation reveals that this phenomenon is owing to the synergistic conjunction of multiscale roughness, structural periodicity, and flexibility, which rectifies the random and localized droplet nucleation (nanoscale and microscale) into a directed and global migration (millimeter-scale). The mechanism we have identified opens up a new approach toward the design of artificial rectifiers for broad applications.
在许多实际应用中，实现固体表面上液滴的定向和远距离传输是广泛期望的，但事实证明这具有挑战性。特别是，液滴在疏水表面上的方向性和传输距离是相互排斥的。在这里，我们报告说，下水道蝇这种即使在非常高的湿度下也能保持不被润湿特性的普遍存在的昆虫，开发出了一种独特的弹道式液滴传输机制来应对这些苛刻的挑战。下水道蝇充当了一个灵活的整流器，允许液滴进行定向和远距离传播以及自我清除，从而抑制不必要的液体泛滥。进一步的研究表明，这种现象是由于多尺度粗糙度、结构周期性和柔韧性的协同结合，它将随机和局部的液滴成核（纳米级和微米级）整合成了定向和全局的迁移（毫米级）。我们所确定的这一机制为设计广泛应用的人工整流器开辟了一条新途径。
