Water droplets that form on a superhydrophobic surface carry an electric charge with them when they "jump," researchers from Massachusetts Institute of Technology (MIT) found.
The discovery could lead to increased power plant efficiency in addition to opening up an entirely new method of drawing power from the atmosphere, according to the study's authors.
Published in the journal Nature Communications, the experiment is an extension of previous work by the MIT team, which revealed that droplets jump under certain conditions. The phenomenon is triggered when two droplets collide on a surface covered with a special superhydrophobic coating. As this happens, the release of excess surface energy causes the droplets to jump.
In the new study, the scientists watched the process using high-speed video. Doing so they discovered that the two droplets "repel one another midflight," according to Nenad Miljkovic, a postdoctoral student at MIT and co-author of the study.
"Previous studies have shown no such effect," Miljkovic said.
The discovery "intrigued" the scientists who realized the effect was caused through the formation of a net positive electrical charge created when the droplets leap off the surface.
The previous discovery that droplets can jump from a condenser surface like those found in power plants provided a method for increasing the efficiency of the transfer of heat on those condensers. The new process holds the potential to increase the efficiency of this process even more.
According to the press release detailing the discovery, "By applying the appropriate charge to a nearby metal plate, jumping droplets can be pulled away from the surface, reducing the likelihood of their being pushed back onto the condenser either by gravity or by the drag created by the flow of the surrounding vapor toward the surface."
Taking this one step further, the scientists explained that, by placing two parallel metal plates across from the other -- one with jumping droplets and the other collecting them -- power can be generated from condensation from the air.
"You just need a cold surface in a moist environment," Miljkovic said, adding that they are currently "working on demonstrating this concept."