Biomimetic 3D-Printed Salvinia molesta Surfaces for Geometry-Driven Wetting Control

Functional bioinspired surfaces have received increasing attention due to their potential in water-repellent, drag-reducing, and antifouling applications. The Salvinia effect, inspired by the leaf of Salvinia molesta, provides a route for the design of water-repellent surfaces, but the complex three-dimensional trichome geometry and the combination of hydrophobic and hydrophilic regions have limited its artificial reproduction. Two-photon polymerization (2PP) offers a direct high-resolution route to fabricate such geometries and rapidly modify local features without molding or multistep lithographic processing. In this work, we demonstrate 2PP fabrication of Salvinia-inspired microstructured surfaces and use them to study geometry-driven wetting in a monomaterial system. The structures consisted of a base trichome geometry fabricated with different print profiles and two apex-modified designs used to probe geometry-driven pinning in the same printed material. The printed microstructures achieved conservative apparent static contact angles (CA) exceeding 135° and a meniscus retention distance of 0.47 mm. These results show that 2PP can decouple the apparent wetting behavior of structured surfaces from the intrinsic hydrophilicity of the printed material.