Fabrication of Smooth, Periodic Surface Structures: Combining Direct Laser Interference Patterning and Electropolishing

Abstract

The manipulation of topography is crucial in surface engineering to customize material properties and surface functionalities for specific applications. Scientists have been inspired by natural surfaces found in plants and animals and have increasingly used engineered surface structures to improve characteristics such as friction, wear, electrical resistance, wettability, and antimicrobial behavior across various fields. Direct laser interference patterning (DLIP) is a technique that can rapidly create well-defined, periodic surface structures. However, it can still face challenges such as surface roughness and non-uniformity, which require complementary post-processing techniques. This article investigates the effectiveness of electropolishing in phosphoric acid as a post-processing method for DLIP-treated copper surfaces. Through systematic characterization and analysis, it is demonstrated that electropolishing selectively smoothens DLIP-treated surfaces by removing undesired by-products, such as oxides and redeposited material while retaining the underlying structure. The real surface area and, consequently, the S ratio are diminished by up to 13%, while the root mean square roughness Rq along the topographic maxima of the line pattern is reduced by ≈90%. These findings contribute to the advancement of our understanding of surface modification techniques and their potential applications in diverse fields.