Bioinspired 1D Anisotropic Double-Spiral Metal Wires for Efficient Fog Harvesting

Innovative design strategies of fog harvesting devices (FHDs) demonstrate promising remedy for water crisis in arid areas. 1D FHDs ensure unimpeded wind circulation and can be manufactured more cost-effectively for extensive regions. Inspired by cactus thorns, desert beetles, and spider silk, two metal organic frameworks (MOFs) functionalized Cu wires with opposite wettability are double-twisted by a mechanical twisting machine, forming 1D double-spiral Cu wires with alternating superhydrophobic/superhydrophilic dual-MOF patterns. The biomimic integration design, namely conical microneedle, stripe-patterned contrasting wettability, and double-spiral geometry, allows for efficient fog water collection due to a collaborative process. Based on such multi-cooperation theory, the optimal fog collection efficiency of dual-MOF functionalized double-spiral Cu wires can reach 0.293 ± 0.013 g cm^-2 min^-1 by investigating the effect of the composition, the diameter ratio and twisting wavelength λ of the two constituent wires. The double-spiral metal wires with discrepant wettability not only propose a facile and cost-effective method for fog harvesting, but also share new physical insight to inspire novel design concepts for efficient fog collection devices, benefitting the fight against the global water crisis.