Enhanced Fog Capture Using Hydrophobic 3D-Printed Micropillar Arrays

The accelerating freshwater crisis is driving an urgent search for sustainable and scalable water-harvesting solutions, particularly for regions where conventional water resources are rapidly diminishing. Here, we report a bioinspired atmospheric water-harvesting platform that couples 3D-printed microarchitectures with precision-engineered surface chemistry to overcome long-standing limitations in fog collection. We fabricated cylindrical micropillar arrays featuring staircase-like hierarchical textures using high-resolution additive manufacturing to enhance nucleation and condensation. Despite the enlarged surface area, the microtextured features exhibited pronounced droplet pinning, severely restricting droplet transport and reducing harvesting efficiency. To mitigate these constraints, we implemented a two-step modification strategy: hydrophobic functionalization via chemical vapor deposition, followed by infusion of nonadecane to create a stable, lubricant-infused slippery interface. The resulting nonadecane-infused micropillar architecture (NMP₃) enabled rapid droplet shedding and directional transport, achieving a fog-harvesting rate of ∼3.6 mL h^-1 under controlled conditions, significantly outperforming unmodified structures. Force-resolved analysis revealed that this enhancement arises from a finely tuned balance between surface-energy-driven mobility and the strong suppression of resistive pinning forces. Our findings demonstrate that the convergence of additive manufacturing and lubricant-infused surface design provides a powerful route to bioinspired, high-performance fog-harvesting systems. This integrated strategy offers a scalable pathway toward next-generation atmospheric water technologies capable of addressing emerging global water challenges.