The Design of Hydrophilic Nanochannel‐Macrostripe Fog Collector: Enabling Wicking‐Assisted Vertical Liquid Delivery for the Enhancement in Fog Collection Efficiency

The design of water collectors that capture atmospheric fogs has been challenging due to the reliability issue. In particular, the small openings of collecting surfaces are often clogged by large‐size droplets. The additional hydraulic resistances added to the collecting surfaces prevent the fog pathways and further lower the overall performance coefficients by decreasing the shade coefficient of the collectors. The clogging issues can be addressed by modulating the fog harvesters' surface chemistry and surface structures to deliver water droplets efficiently and to prevent re‐entrainment of droplets to the openings. Herein, the novel design of fog collectors that consist of both nanochannels and macrostripes is demonstrated. The combination of those two structures provides the anisotropic wettability and thereby directional spreading in the longitudinal direction to the nanochannels. The directional liquid spreading facilitates continuous liquid transport through the formation of a thin liquid film. As a result, the fog collector successfully enhances the fog harvesting performance by 50% compared to conventional mesh‐like fog collectors. The design of a reliable fog collector is still challenging due to the clogging of the collector with water, which may lower the fog harvesting efficiency. Herein, the hydrophilic nanochannel‐macrostripe fog collector is shown, which has an anisotropic wettability and directional wicking property, enabling continuous liquid transport by preventing the clogging of the fog collector.