Controllable droplet self-transport on multi-bioinspired slippery liquid-infused microstructure surface

Abstract

Inspired by Nepenthes pitcher plant, the surface infused by slippery liquid could significantly reduce the adhesive force and facilitate the movement of droplet. Combined with the gradient structure of cactus spine, the slippery liquid-infused microstructure surfaces (SLIMS) could achieve the droplet self-transport without external energy input. However, combined with experimental findings on the SLIMS with uniformly rough structure, the self-transport distance is still limited by the wedge angle and droplet volume. Although the transport distance can be improved by reducing the wedge angle and increasing the droplet volume, we have demonstrated the control of transport distance by processing different structures on the surface. Benefited from the directional wettability of the V-shaped prism microarray (VPM) surface, the self-transport distance could be controlled in the case of fixed liquid volume and wedge angle. A fraction of the lubricating oil would be squeeze away when the droplet with larger density was dropped on the surface, which can form local contact between droplet and VPM structure. This would result in the imbalance Laplace pressure along the movement direction, which can be further manipulated by the VPM structure. The multi-bioinspired surface provides a new insight for precise liquid manipulation, which could promote liquid directional transport developments in theoretical analysis and further practical applications.