Surfaces directing fluid flows Although surfaces can be made to attract or repel liquids using coatings, surface textures with specific curvature can also be used to achieve the same effect. However, fluid transport is usually limited by the specific pattern that only drives flow at the surface itself. Feng et al . created a dual-reentrant surface that has an asymmetric profile so that fluids spread out at the surface and subsurface layers. Furthermore, these surfaces can be designed so that different liquids will naturally steer in opposing directions simply because of their specific interactions with the surface. —MSL

No abstract

A droplet impacting on inclined surfaces yields more complex outcomes than on normal impact and the effect of the inclining angle on the impact dynamics is still in controversy. Here, we show that a drop impacting on inclined superhydrophobic surfaces exhibits an asymmetric rebound with a distinctive spreading and retraction along the lateral and tangential directions. Meanwhile, there is an obvious contact time reduction with the increase of the inclining angle and impact velocity. We demonstrate that the contact time reduction is attributed to the asymmetric drop spreading and retraction, which endows a fast drop detachment. Simple analyses are presented to interpret this phenomenon, which is in a good agreement with the experimental results.

Designing intelligent slippery surfaces for droplet manipulation is critical for many applications from drug delivery to bio‐analysis, while is of great challenging in sustainability for inescapable wastage of lubricant layer. Herein, an ultrafast lubricant self‐mediating (self‐replenishing/‐absorbing) photothermal slippery surface is designed that achieves sustainable transport of droplet under the irradiation of near infrared light (NIL) even if the lubricant layer is wiped clean completely, as well as at other man‐made extreme conditions. The ultrafast lubricant self‐mediating performance is caused by synergistic effects of interconnection of porous structure and photothermal expansion of the material. When lubricant on surface is lost, photothermal expansion of material can quickly squeeze the lubricant inside the base to flow into and out of the interconnected porous structure to generate a fresh lubricant layer. Attractively, when the NIL is turned off, the rebuilt lubricant layer can be swiftly self‐absorbed into the porous to inhibit unnecessary wastage. Moreover, an arbitrary split of droplet in desired configurations can be achieved by controlling the NIL irradiating route. This sustainable droplet manipulation induced by ultrafast lubricant self‐mediating can be extensively applied in microfluidics and micro‐reactor settings.

No abstract