Laplace Pressure Driven Single-Droplet Jumping on Structured Surfaces
Laplace Pressure Driven Single-Droplet Jumping on Structured Surfaces
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DOI：
10.1021/acsnano.0c03487
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发表时间：
2020-10-27
期刊：
影响因子：
17.1
通讯作者：
Miljkovic, Nenad
中科院分区：
文献类型：
--
作者：
Yan, Xiao;Qin, Yimeng;Miljkovic, Nenad
液滴在表面上的传输和从表面脱落在自然界中普遍存在，并且是控制包括生物流体、自清洁、防冰、水收集和电子热管理的应用的关键现象。通过表面-液滴相互作用实现自发液滴脱落的常规方法受到低液滴传输速度和能量转换效率的影响。在这里，通过在空间上限制增长的液滴，并通过合理设计的凹槽使松弛，我们实现了微米和毫米液滴的单液滴跳跃，无量纲跳跃速度v* 接近0.95，显着高于传统的被动方法，如聚结诱导液滴跳跃（v* 接近0.2-0.3）。单液滴跳跃的机制，阐明通过研究槽的几何形状和局部钉扎，优化表面设计提供指导方针。我们发现，合理的设计的凹槽，使灵活的控制液滴跳跃速度，方向和大小，通过剪裁的本地钉扎和拉普拉斯压力差。我们成功地利用这种以前未观察到的机制作为一种手段，在蒸汽冷凝液滴的快速去除。我们的研究展示了一种被动的方法，用于快速，高效，定向和表面钉扎耐受运输和脱落的液滴具有微米至毫米的长度尺度
Droplet transport on, and shedding from, surfaces is ubiquitous in nature and is a key phenomenon governing applications including biofluidics, self-cleaning, anti-icing, water harvesting, and electronics thermal management. Conventional methods to achieve spontaneous droplet shedding enabled by surface-droplet interactions suffer from low droplet transport velocities and energy conversion efficiencies. Here, by spatially confining the growing droplet and enabling relaxation via rationally designed grooves, we achieve single-droplet jumping of micrometer and millimeter droplets with dimensionless jumping velocities v* approaching 0.95, significantly higher than conventional passive approaches such as coalescence-induced droplet jumping (v* approximate to 0.2-0.3). The mechanisms governing single-droplet jumping are elucidated through the study of groove geometry and local pinning, providing guidelines for optimized surface design. We show that rational design of grooves enables flexible control of droplet-jumping velocity, direction, and size via tailoring of local pinning and Laplace pressure differences. We successfully exploit this previously unobserved mechanism as a means for rapid removal of droplets during steam condensation. Our study demonstrates a passive method for fast, efficient, directional, and surface-pinning-tolerant transport and shedding of droplets having micrometer to millimeter length scales