In a feat of biomimicry, engineers have created superhydrophobic and superhydrophilic surfaces capable of trapping, directing and repulsing water. The implications for medicine, energy and environmental resourcefulness are endless.
The surfaces are modeled after the back of a beetle found in the Namib Desert of Africa.
The beetle, called Stenocara, has waxy bumps, some of which are hydrophobic (water-repellant), repulsing water onto the other bumps, which are hydrophilic (water-loving). Then the beetle tips its head and drinks the water that collects on its back. There is enough to quench its thirst--up to 12 percent of the beetle's body weight in water accumulates each day.
The beetle's water collection system was discovered over 10 years ago. Soon after the discovery, excited engineers and scientists decided to study the process and create nanoscale surfaces capable of applying the water collection system to practical human use. Thanks to many recent developments in nanoscience and fluid physics, this engineering feat was successful. Furthermore, engineers can now turn their attention to applying the technology to larger scale developments.
Such superhydrophic surfaces are already in the market as chemical coatings on clothing and devices. The surfaces "have enabled us to create devices--devices with the potential to help humanity--that do things much better than have ever been done before," says NSF-funded mechanical engineer Constantine Megaridis of the University of Illinois.
Megaridis and his colleagues have made microfluidic circuits that can transport a wide variety of liquids at high rates. Other engineers have created plastic strips that can combine or separate fluids for medical diagnostic tests.
"Imagine you want to bring drops of blood or water or any liquid to a certain location. Just like a highway, the road is the strip for the liquid to travel down, and it ends up collecting in a fluid storage tank on the surface," Megaridis explained.
NBD Nanotechnologies is looking to use the beetle-inspired surface coatings to improve condensation efficiency. Condensed water forms a film that takes away droplets, but using a superhydrophobic surface increases the rate of condensation, making the process more efficient. Machines that use condensers, such as refrigerators, cars and air conditioners, would all operate more efficiently and with less energy.
The primary challenge Megaridis and NBD face now is ensuring the durability of the superhydrophobic surface structures. With better durability, they will be able to meet large-scale goals such as installing the surfaces in power plant condensers. These projects, the researchers say, will help with the water and energy shortages the world faces.
