Feng Shile, Wang Sijie, Tao Yuanhao, Shang Weifeng, Deng Siyan, Zheng Yongmei, Hou Yongping
Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, Beijing Key Laboratory of Bio-inspired Energy Materials and Devices School of Chemistry and Environment Beihang University. Beijing, 100191 (P. R. China).
Sci Rep. 2015 May 15;5:10067. doi: 10.1038/srep10067.
A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology.
通过简单的一步阳极氧化工艺在石墨板表面制备了径向可润湿性梯度。研究发现，通过调节电流和氧化时间梯度，可以轻松控制可润湿性梯度的方向和数值。随着表面温度的升高，表面上的液滴不仅表现出沸腾模式的转变，还呈现出可控的径向扩散、蒸发和移动行为。这些现象可归因于润湿性力、滞后力和蒸气压（莱顿弗罗斯特效应）的协同作用。特别是，在具有内部或外部径向梯度的表面上实现了高速液滴的可控径向汇聚或发散，这在微流控器件设计和生物技术探索中将具有关键应用。
