Cicadas Might Help Humans Discover New Hydrophobic Materials
ARI SHAPIRO, HOST:
Cicadas are those noisy insects that keep the summer buzzing. Well, it turns out they've evolved an interesting trick - staying dry in the pouring rain. NPR's Joe Palca has the story of how they pull it off and how it might lead to interesting materials for humans.
JOE PALCA, BYLINE: Marianne Alleyne studies cicadas - in particular, cicada wings and, more particular, tiny bumps on the wings called nanostructures. Alleyne says there are two kinds of cicadas - annual cicadas that show up annually and periodic ones that only appear, well, periodically.
MARIANNE ALLEYNE: But we mostly focus on the annual cicadas because they have really cool nanostructures that actually result in this superhydrophobicity, which then also results in...
PALCA: So wait a minute. Did you - sorry, did you really just use the word superhydrophobicity?
ALLEYNE: Yes (laughter). Yes, yes.
PALCA: What does that mean?
ALLEYNE: So, you know, hydrophobicity is when it just repels water.
PALCA: And superhydrophobicity is when water practically jumps off the surface. Alleyne says she has money from the U.S. Army to study the nanostructures on the wings to better understand how this water-repellent system works. It has something to do with the shape and composition of the nanostructures. She says the Army supports her work because they want to know if it's possible to use a similar system to make waterproof fabric or medical tubing that liquids will flow through with little resistance.
Now, there are sophisticated devices to study the nanostructures.
ALLEYNE: We use scanning electron microscopy. We use atomic force microscopy.
PALCA: But Alleyne also uses nail polish. Turns out you can paint nail polish onto the wing, let it dry and peel it off. That gives you a mold with the nanostructure shapes embedded in it. Then you pour a metal or plastic into the mold.
ALLEYNE: And now by using nail polish remover, you can take the template away and you get these perfectly shaped nanopillars out of it.
PALCA: Alleyne thinks a version of this system is scalable, so it might be a way of making the materials the Army is hoping for. But Alleyne isn't a material scientist or an engineer. She has a different reason for being excited about the nail polish idea.
ALLEYNE: For me as a biologist, I love having this material that is based on cicadas to help us explain what we're actually seeing in nature and why this came about.
PALCA: Because that's what scientists do - study how things come about.
Joe Palca, NPR News.
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