We humans like to think we’re so clever, but in many cases nature has beaten us to the punch with a better version. The newest example comes from a humble insect that’s probably in your own backyard, which makes nanoscale soccer balls that hide it from predators – inspiring better UV protection, sunscreens and maybe even cloaking tech.
Leafhoppers are a common insect often found in gardens or on farms, where they’re considered a pest to crops. They’re pretty unremarkable in most aspects, except for one unique feature that’s never been found in any other insect – leafhoppers produce incredibly complex nanoparticles called “brochosomes,” which look like tiny soccer balls. These hollow spheres are about half the size of a single bacterium, filled with tiny pores, and are surprisingly uniform across species of different sizes living in different parts of the world.
“That makes us ask a question,” said Tak-Sing Wong, lead author of the study. “Why this consistency? What is the secret of having brochosomes of about 600 nanometers with about 200-nanometer pores? Does that serve some purpose?”
Leafhoppers secrete these brochosomes, and then coat their whole bodies in them, which seems to have a few benefits. For one, the particles have been found to be superhydrophobic, which could protect the bugs from water and their own super-sticky pee. They also seem to do strange things to light, so to investigate, researchers at Penn State University set out to make their own brochosomes in the lab and test them.
Making objects that tiny is tricky, so the team created larger scale models of them – although “larger” is of course relative, since they were still only 20,000 nanometers wide. Then, they shone infrared light of different wavelengths onto them, and watched how it interacted with the brochosomes. And sure enough, they found the particles cut almost all light reflection, suggesting their primary purpose is to cloak the insects from predators.
“It has been unclear why the leafhoppers produce particles with such complex structures,” said Lin Wang, lead author of the study. “We managed to make these brochosomes using a high-tech 3D-printing method in the lab. We found that these lab-made particles can reduce light reflection by up to 94%. This is a big discovery because it's the first time we've seen nature do something like this, where it controls light in such a specific way using hollow particles.”
While their scale models were tested with infrared light, the team says that natural brochosomes are the right size to do the same thing with ultraviolet wavelengths. That could be key to their purpose – birds and reptiles hunt with UV vision, so leafhoppers could be scrambling those signals to save their own hides.
The find isn’t just an insight into ingenious insects, it could also help inform a range of new technologies. The team suggests that it could improve surfaces that collect solar energy, make coatings that scatter UV light to protect objects and our own skin from Sun damage, and if we want to get real sci-fi with it, maybe even cloaking technology.
“This discovery could be very useful for technological innovation,” said Wang. “With a new strategy to regulate light reflection on a surface, we might be able to hide the thermal signatures of humans or machines. Perhaps someday people could develop a thermal invisibility cloak based on the tricks used by leafhoppers. Our work shows how understanding nature can help us develop modern technologies.”
The research was published in the journal PNAS.
Source: Penn State University
