Directional and Adaptive Oil Self‐Transport on a Multi‐Bioinspired Grooved Conical Spine

Abstract

Manipulating oil droplets in an aqueous solution offers great opportunities to develop advanced devices in the fields of water remediation, chemical micro-reactor, etc. Although conical structures can achieve a directional oil droplet motion, the continuous and adaptive fluid self-transport in complicated environments is still a challenge. Inspired by the distinctive oil transport capability of fishbone and the anisotropic grooved structure of rice leaves, this work presents a multi-bioinspired grooved conical spine (BGCS) for improved oil manipulation. Benefiting from the cooperative effect of the asymmetric Laplace pressure and the surface capillary force, the BGCS possesses the reliable functions of ultrafast and continuous oil transport under water, in air, and even across the air-water interface. Compared with the original cone, the BGCS demonstrates a nine times faster transporting velocity and a five times larger capacity. It is envisioned that this updated oil-collecting cone with its cooperative structure should find real-world applications.

Simulation investigation of the spontaneous motion behaviors of underwater oil droplets on a conical surface

“…The Laplace force ( F d ) is induced by the gradient Laplace-pressure of the asymmetrical droplet morphology, which acts as a driving force. 13 The frictional resistance arises from the interface between the oil droplet and cone, which is proportional to the contact area of the droplet–solid interface. 27 The viscous resistance is generated from the interfacial shear resistance between the oil droplet and water (bulk), which is proportional to the dynamic viscosity of the continuous phase and the velocity of the droplet.…”

“…More importantly, a conical surface can also be used to transport oil droplets underwater, showing a wide range of promising applications such as in the manipulation of a low surface tension liquid. 13 For example, Jiang et al 14 proposed a bionic array of conical needles to efficiently collect micron-sized oil droplets from an oil–water emulsion. Although conical structures have been used to directionally transport droplets, the precise manipulation of droplets particularly oily droplets is still a challenge because the dynamic behavior of a droplet on the cone is poorly understood.…”

Wetting Ridge‐Guided Directional Water Self‐Transport

“…In nature, lots of creatures have evolved unique microscaled structures with the ability to spontaneous and directional liquid transport. [ 14 , 15 , 16 , 17 , 18 , 19 ] For instance, the Araucaria leaf, which is composed of periodically arranged 3D ratchets with transverse and longitudinal reentrant curvatures, allows the fluids with different surface tension to spread along different directions. [ 20 ] Namib desert beetle can harvest water droplets from the fog by using their heterogeneous wettability structured back that consists of wax‐coated hydrophobic regions and non‐waxy hydrophilic bumps.…”

A superhydrophobic surface with a synergistic abrasion–corrosion resistance effect prepared by femtosecond laser treatment on an FeMnSiCrNiNb shape memory alloy coating

“…The hydrophobic SiO 2 nanoparticles (15–20 nm, 1.2 g) were dispersed in ethanol (50 ml), which was stirred for 2 h at 600 rpm and ultrasonicated for 30 min to obtain a uniformly distributed solution. Then, a spray gun was used to spray the solution on the SMA/Nb composite coating surface for achieving superhydrophobicity, 29–31 where the spray pressure was 0.8 MPa and the distance from the coating was 10 mm. The entire process is shown in Fig.…”