Scientists have found that the bumpy shell of the desert-dwelling Namib beetle is more than just a protective layer. As a matter of fact, the beetle’s bumpy shell help the insect to survive the desert by also extracting moisture from the air.
And now scientists from Harvard University are using this idea—along with similar functions of cacti, the pitcher plant, and other organisms—to develop a way to collect water in places where it is quite sparse.
The team calls this technology “Slippery Liquid-Infused Porous Surfaces.” It collects and directs the flow of condensed water droplets, which overcomes one of the many challenges in harvesting atmospheric water: controlling the size of the droplets they form and, also, the direction in which they flow. Until now, this collection was somewhat random and inefficient.
For many years, researchers had focused on the hybrid chemistry of the beetle’s bumps—basically, a hydrophilic top with hydrophobic surroundings—to help explain how the the insect is able to attract water. But they failed to look any closer. Now, however, they have taken to investigating further and are taking inspiration from the convex bumps themselves.
Harvard University postdoctoral researcher, Kyoo-Chul Park comments, “We experimentally found that the geometry of bumps alone could facilitate condensation.”
The lead study author goes on to say, “By optimising that bump shape through detailed theoretical modelling 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 compared to other surfaces.”
Park also continues, “Without one of those parameters, the whole system would not work synergistically to promote both the growth and accelerated directional transport of even small, fast condensing droplets.”
In the study, which has been published in the journal Nature, Harvard’s Joanna Aizenberg also notes, “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.”
The hope, of course, is to use this technology to improve many things in society and not just fabrics and materials in arid regions (though that is a major benefit).
Study co-author Philosek Kim comments, “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.”