Slippery microgrooves help harvest fog

Collecting moisture from air is a promising technique for providing water to the world’s arid regions. But the hydrophilic surfaces that are sometimes used for this purpose prefer to hold on to water rather than give it up for consumption. Scientists from Pennsylvania State University and the University of Texas, Dallas, have now developed a lubricated hydrophilic surface that both attracts and sheds water efficiently, thanks to parallel, microscopic grooves etched into the surface that promote drainage (Sci. Adv. 2018, DOI: 10.1126/sciadv.aaq0919). The microgrooves, which also provide increased surface area on which droplets can form, are coated with a thin layer of hydrophilic lubricant that is held in place by nanoscale roughness on the surface. In simulated foggy conditions provided by a conventional room humidifier, the grooved, lubricated surfaces outperformed a variety of other hydrophilic surface structures, as well as water-repellent surfaces, in both droplet formation and shedding.