Microfabrication of Fish Scale-Inspired Surfaces via Glancing Angle Deposition (GLAD) With Line Seeds

Abstract

Abstract This paper presents an innovative micro fabrication process for fish scale inspired surfaces, achieved through glancing angle deposition (GLAD) with line seeds. Fish scales exhibit diverse shapes, sizes, and distributions. Artificial surfaces mimicking fish scales can be scaled-up for practical applications, such as antifouling coatings, swimsuits, and solar energy harvesting devices. While previous researches have explored recreating fish scale surfaces using micro/nano fabrication techniques like additive manufacturing and nanoimprint lithography, certain challenges persist. In response, we propose recreating both leptoid and placoid scales using GLAD. GLAD is a physical vapor deposition process that generates intricate three-dimensional (3D) micro and nanostructures by harnessing the shadowing effect of nucleation sites for directional vapor deposition control. Using these pre-determined nucleation sites (also called seeds), one can transform two-dimensional line seeds into three-dimensional stacking features, while also customizing the size, shape, and distribution of the scales. This paper offers a comprehensive exploration of the line seed design for replicating fish scales. It further delves into the fabrication process, covering both line seeding through conventional photolithography and the GLAD procedure. After one GLAD session using Ge as the material, a 20 nm parylene layer is applied to enhance surface robustness. The resulting surfaces, mimicking fish scales, undergo rigorous testing for their hydrophobic properties, exhibiting a water contact angle exceeding 110 degrees.