Taking inspiration from the beaks of shorebirds, scientists say they have developed an efficient artificial equivalent that can collect water from fog or dew as a possible partial solution to drought.
Watching how long-billed shorebirds pull food into their throats by alternately opening and closing their beaks, engineers at the University of Texas at Arlington wanted to see if the same action could pull in water, so they created a water-collecting device consisting of two glass plates joined at their edges with a hinge.
When fully open, the plates' large surface would allow fog to condense on them as water beads; when the collector closed, the water drops would slide down into a collecting tube at the hinged edge, engineering professor Cheng Luo and his doctoral student Xin Heng report in the American Chemical Society journal Applied Materials & Interfaces.
"We wanted to see if we could do that first," Luo said. "When we made the artificial beaks, we saw that multiple water drops were transported by narrow, beak-like glass plates. That made us think of whether we could harvest the water from fog and dew."
Birds aren't the only species to gather water directly from the air, the researchers point out; desert beetles, cacti and grasses also collect water on their surfaces when a misty fog rolls into otherwise dry environments.
In initial experiments, about a tablespoon of water was collected by a single 4-inch by 10-inch prototype artificial "beak" in a little more than a half hour, the researchers say.
In two hours, between 400 to 900 times more liquid water was collected than by any natural process or other artificial fog-collecting setups, they report.
Theirs is not the first attempt at fog collecting. MIT researchers, working with research colleagues in Chile, have managed to harvest potable water from the fogs that form in that country's coastal regions, one of the driest areas on Earth.
Their system, instead of plates, used a system of mesh structures place on the tops of hills that see constant fog and prevailing westerly winds.
About half the area of the Earth's land masses are covered by deserts or semi-arid areas, the Texas researchers say. This means potable water often has to be trucked in for people living in the regions who have no underground or surface supplies.
Efficient fog collectors such as their artificial beaks could offer a more sustainable way to provide water, they say, in parched areas from Saudi Arabia to the western U.S., currently in the grip of an extended drought.
"And really, if this method could be mass-produced, it could be used anywhere in the world where fog or dew exist," Luo said.
