Bioinspired Curvature-Driven Droplet Transport on Slippery Lubricant-Infused Elastomeric Surfaces for Efficient Passive Fog Collection

Atmospheric fog harvesting is a promising route for decentralized water production, yet its efficiency remains limited by droplet pinning and dissipative transport. Here, we address these constraints through a bioinspired strategy that integrates cactus-like conical geometries with slippery lubricant-infused elastomeric (SLIE) coatings based on PDMS–silicone oil networks to regulate droplet dynamics. The SLIE interfaces exhibit consistently low contact angle hysteresis across liquids of varying surface tensions, confirming robust omniphobicity. Unlike conventional liquid-infused surfaces, the PDMS-based slippery elastomeric interfaces eliminate observable droplet cloaking and exhibit low contact angle hysteresis, promoting sustained low-dissipation droplet transport suitable for fog harvesting. This synergy between surface chemistry and geometric asymmetry results in a significant enhancement in fog harvesting performance. SLIE-functionalized conical substrates achieve up to (∼150%) higher water collection rates compared to hydrophilic controls, driven by reduced viscoelastic resistance and accelerated droplet shedding. Furthermore, decreasing cone apex angles (5°–10°) amplifies Laplace pressure gradients, leading to earlier droplet mobilization and improved collection efficiencies relative to larger cone angle geometries (30°–45°). These findings establish a mechanistic design framework that integrates omniphobic liquid interfaces with curvature-induced transport, providing a scalable strategy for next-generation passive water harvesting systems.