Abstract
Surfaces that exhibit anisotropy, widely found in nature, promote one-dimensional water control by relying on well-organized features. A comprehensive understanding of the wetting behavior of organic liquids, especially the movement of water and oil liquids on the surface, including the manipulation of water droplets, the separation of water and oil, and the cleaning of the ocean, are of great significance. Here, The filefish Navodon septentrionalis has an anisotropic oleophobicity underwater owing to its distinctive skin, which allows it to self-clean oil droplets from its body. Filefish skin has oriented microscaled hook-like spines arranged in an array pattern that contributes to this prominent wetting anisotropy. Considering the performance at a micron level and the variable arrangement, conventional approaches are ineffective in simulating the natural skin structure. Due to its capabilities of high productivity, cost-effectiveness, rapid production, as well as the ability to fabricate microstructures, additive manufacturing (AM), also known as 3D printing, has gained considerable attention in various academic fields. Specifically, we utilize a 3D printing method to fabricate biomimetic structures that resemble the arrangement of spines on the skin of filefish. In order to quantitatively evaluate the hydrophobicity of a 3D-printed surface, four different arrangements of spines were displayed on the surface, including the original surface arrangement, the surface with movement, the surface with rotation, as well as the surface that has both movement and rotation. Each surface arrangement has a level of surface hydrophobicity, with moving and rotating surfaces possessing the greatest level of hydrophobicity. This study provides an opportunity to investigate the wettability of biological surface structures with specific arrangements and offers good prospects for oleophobicity studies and a variety of subsequent applications such as water-oil separation, and oil collection devices.
