Evaporation-triggered directional transport of asymmetrically confined droplets
Evaporation-triggered directional transport of asymmetrically confined droplets
复制标题
蒸发触发的不对称约束液滴的定向传输
DOI：
10.1016/j.jcis.2021.06.164
复制
发表时间：
2021
影响因子：
9.9
通讯作者：
Cheng, Jiangtao
中科院分区：
文献类型：
--
作者：
He, Xukun;Cheng, Jiangtao
假设当液滴被限制在两个具有二面角α的非平行疏水表面之间时，其行为很大程度上受到非对称限制的影响。在蒸发过程中，限制下的液滴形态将不断演变，导致液滴朝向尖点的定向运输。实验与模拟在蒸发过程中，实验观察到在不同初始位置的液滴从尖点向尖点的传输。使用Surface Evolver进行了一系列模拟，以获得受限液滴的三维形貌。力和能量的分析，揭示了主导蒸发触发驱动和运输的机制。结果-体积V的不对称限制的液滴将漂移到平衡位置的L E的尖瓣具有最低的能量。在蒸发过程中，由于le的不断减小，导致了它的定向运动，其标度为le ~ α-1V13。在此，蠕动和滑动模式的传输可以被描述为准稳定和不稳定的自松弛过程的液滴从拉伸区到平衡区，分别。我们对液滴驱动的内在机制的研究结果揭示了一种被动和决定性方式操纵受限液滴行为的新方法。
Hypothesis When a liquid droplet is confined between two non-parallel hydrophobic surfaces with dihedral angle α, its behavior is largely influenced by the asymmetric confinement. During evaporation, the droplet morphology under confinement will continuously evolve, leading to the directional transport of the droplet towards the cusp. Experiments and Simulations During the evaporation process, droplets at different initial locations l 0 from the cusp were experimentally observed to transport towards the cusp. A series of simulations using Surface Evolver were performed to obtain the three-dimensional morphologies of the confined droplets. Force and energy analyses were conducted to unveil the mechanisms dominating the evaporation-triggered actuation and transport. Findings The asymmetrically confined droplet of volume V would drift towards an equilibrium location of l e from the cusp with the lowest energy. Its directional motion results from the consecutively decreasing l e, which is scaled as l e~ α-1 V 1 3 during evaporation. Herein, the creeping and slipping modes of transport could be characterized as the quasi-stable and unstable self-relaxation processes of droplet from the stretched regime to the equilibrium regime, respectively. Our findings on the intrinsic mechanism of droplet actuation shed light on a novel approach to manipulating the confined droplet behaviors in a passive and decisive fashion.