Despite their simplicity, water droplets manifest a wide spectrum of forms and dynamics, which can be actuated using special texture at solid surfaces to achieve desired functions. Along this vein, natural or synthetic materials can be rendered water repellent, oleophobic, antifogging, anisotropic, etc.—all properties arising from an original design of the substrate and/or from the use of special materials promoting capillary or elastic forces at the droplet scale. Here, we report an original phenomenon occurring at the tip of asymmetric (half-flat, half-curved) pillars: Droplets reconfigure and get oriented on the curved side of these Janus tips. This local, geometry-driven effect, namely, tip-induced flipping of droplets, is found to be generic and have spectacular global consequences: Vast assemblies of Janus pillars enable a continuous, long-range, and fast self-transport of water harvested from fogs, which makes it possible to collect and concentrate droplets at different scales.

尽管水滴很简单，但它表现出多种形式和动力学，可以使用固体表面的特殊纹理来驱动它们以实现所需的功能。沿着这种思路，天然或合成材料可以具有防水、疏油、防雾、各向异性等特性——所有特性均源自基材的原始设计和/或使用促进液滴处毛细管或弹力的特殊材料规模。在这里，我们报告了在不对称（半平坦、半弯曲）柱的尖端发生的原始现象：水滴在这些 Janus 尖端的弯曲侧重新配置并定向。这种局部的、几何驱动的效应，即尖端引起的水滴翻转，被发现是普遍存在的，并且具有惊人的全球性后果：Janus 柱的巨大组件能够实现连续、远距离和快速的自运输，从雾，这使得收集和浓缩不同尺度的液滴成为可能。