Nature-inspired system to pull water from thin air

Inspired by a desert beetle, cactus and pitcher plant, researchers from Harvard University have designed a new material to collect water droplets from thin air that can one day help fill the drying reservoirs on our planet.

The team from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering drew inspiration from these organisms to develop a better way to promote and transport condensed water droplets.

"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," explained Joanna Aizenberg, the Amy Smith Berylson professor of materials science at SEAS.

Organisms such as cacti and desert beetles can survive in arid environments because they have evolved mechanisms to collect water from thin air.

The Namib desert beetle, for example, collects water droplets on the bumps of its shell while V-shaped cactus spines guide droplets to the plant's body.

The new system, described in the journal Nature, is inspired by the bumpy shell of desert beetles, the asymmetric structure of cactus spines and slippery surfaces of pitcher plants.

The material harnesses the power of these natural systems, plus Slippery Liquid-Infused Porous Surfaces technology (SLIPS) developed in Aizenberg's lab, to collect and direct the flow of condensed water droplets.

This approach is promising not only for harvesting water but also for industrial heat exchangers.

Thermal power plants, for example, rely on condensers to quickly convert steam to liquid water.

"This design could help speed up that process and even allow for operation at a higher temperature, significantly improving the overall energy efficiency," added Philseok Kim, vice president of technology at SEAS spin-off SLIPS Technologies, Inc.

The major challenges in harvesting atmospheric water are controlling the size of the droplets, speed in which they form and the direction in which they flow.

"This research is an exciting first step towards developing a passive system that can efficiently collect water and guide it to a reservoir," Kim noted.