Bioinspired functional surface with curved topography and dual heterogeneous wettability for enhanced fog collection

Conventional non-uniform wettability surfaces typically employ hydrophilic surfaces for water collection and hydrophobic surfaces for water drainage. Such surfaces often suffer from droplet pinning, leading to widespread surface coverage by liquid bridges that obscure functional surfaces or structures. Inspired by the curved back structure of beetles and the grooved veins of rice leaves, this study designed a functional surface integrating curved geometric features with dual heterogeneous wettability (DHWS). Using electrical discharge wire cutting and nanosecond laser processing techniques, curved surface arrays and micro-groove structures were fabricated on copper content of 62 % brass surfaces. Combined with the wettability contrast between a waxy hydrophobic coating and hydrophilic channels, this enables efficient droplet nucleation, rapid coalescence, and directional transport. On this surface, the curved structures significantly enhance droplet nucleation efficiency. The unique U-shaped grooves accelerate droplet coalescence, while the hydrophobic-hydrophilic wettability difference promotes rapid droplet drainage along the hydrophilic channels via capillary forces. Compared to traditional fog collection surfaces, this wettability reversal design (hydrophobic collection / hydrophilic drainage) coupled with groove-accelerated coalescence can largely eliminate droplet pinning. This prevents liquid bridges from forming due to droplets lingering on the surface, thereby avoiding obstruction of subsequent fog collection. Ultimately, the DHWS achieved a water collection efficiency of 0.668 g·cm −2 ·h −1 , representing a 98 % improvement over the original surface. This research elucidates the mechanism by which curved geometric morphology and wettability synergistically regulate droplet behavior. The findings hold significant promise for applications in water resource management and environmental protection. • Hydrophobic water capture / hydrophilic drainage design. • Beetle-inspired curves + rice leaf-like U-grooves with dual wettability. • Curvature boosts nucleation; grooves accelerate coalescence & directional transport.