Droplet Transportation on Janus Harp Wires for Enhanced Fog Harvesting

Ensuring freshwater resources is a vital issue for human beings worldwide. Fog harvesting is one promising way to provide water from unconventional sources. However, clogging by the captured liquid depresses the fog harvesting performance. Here, a harp-shaped Janus harvesting system, which has thin wires with a superhydrophobic side facing the fog stream and a superhydrophilic back side to transport the droplets, is used to yield simultaneous fog capturing and water transport abilities. Attached droplets on the Janus wire transported along the periphery avoided clogging and enhanced the performance. The Janus system thus suppressed the increase and fluctuations of actual shade coefficients, which indicated blockage of the fog stream. This optimized the design of the harvester. Experiments using a multilayered Janus harvester demonstrated a significant enhancement compared with that constructed with mono-wettability wires. Overall, the results indicated the promise of droplet transportation on single wires for improving fog harvesting, as well as for other applications such as oil mist recovery and demulsification.