Desert Beetles, Cacti and Pitcher Plants Inspire New Water Harvesting Techniques

By mimicking the shell geometry of Namib desertr beetles, researchers from Harvard University have developed improved methods of water harvesting. In fact, researchers were able to make water drops grow six times faster than normal by copying the insects' bumpy shells.

Certain organisms, including cacti and desert beetles, can survive in arid environments because they've evolved mechanisms to collect water from thin air. For example, the Namib Desert beetle collects water droplets on the bumps of its shell from periodic, foggy winds in the desert, while V-shaped cactus spines guide droplets to the plant's body. A combination of these two techniques allowed researchers to create drops that not only grew fast, but that also grew larger as temperatures increased, according to a news release. 

The hope, researchers say, is to use their findings to improve the collection and transport of water droplets and electricity generation.

"Everybody is excited about bio-inspired materials research," Joanna Aizenberg, one of the study researchers, said in the release. "However, so far, we tend to mimic one inspirational natural system at a time. Our research shows that a complex bio-inspired approach, in which we marry multiple biological species to come up with non-trivial designs for highly efficient materials with unprecedented properties, is a new, promising direction in biomimetics."

A little drop of water may seem insignificant but thermal power plants, for example, rely on condensers to quickly convert steam to liquid water. The physical processes involved in both the formation and movement of the liquid are also essential in desalination and air conditioning systems. The recent study discovered the physical arrangement and location of the beetles' bumps is key to successfully harvesting water. 

"We experimentally found that the geometry of bumps alone could facilitate condensation," Kyoo-Chul Park, first author of the study, added. "By optimizing that bump shape through detailed theoretical modeling and combining it with the asymmetry of cactus spines and the nearly friction-free coatings of pitcher plants, we were able to design a material that can collect and transport a greater volume of water in a short time."

While researchers expected larger droplets to form on colder surfaces, their study revealed the opposite effect with bigger drops forming at higher temperatures. They say this could greatly benefit hot, dry environments where water droplets often evaporate before they can be harvested. 

Their findings, recently published in the journal Nature, have important implications as water scarcity becomes a growing problem worldwide. 

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