At The Nano Level, Wrinkles Aren't Always A No-No

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What happens when you add folds to materials that are only a few atoms thick? Several scientists set out to find the answer — and discovered that these nano-wrinkles can be quite useful.


Now time for more unfolding science. Now time for more unfolding science. NPR science correspondent Joe Palca has been regaling us this summer with stories of how things fold and unfold in the natural world. Today, he tells us what happens when you fold the materials that are only a few atoms thick.

JOE PALCA, BYLINE: Usually, we try to iron out wrinkles in things like shirts and sheets, but when you get down to materials that are only a few atoms thick - the world of nanomaterials - having a few nano-wrinkles in a flat sheet can be useful. For example, if you take an invisibly thin sheet of carbon atoms and wrinkle it in a very specific way, the sheet can actually repel water. Coat a wall with such a material and.

KYUNG-SUK KIM: Any water droplet hit the service - it bounces like a tennis ball. It goes out.

PALCA: Kyung-Suk Kim is a professor of engineering and director of the Center for Advanced Materials Research at Brown Unitversity. Kim studies all kinds of folds in nanomaterials, and he's found many with useful properties. There's a nano-ridge that can catch nanoparticles, making a nano-lubricant. There are nano-crinkles which you get when you stack up sheets with nano-wrinkles. Sheets with nano-crinkles can hold an electric charge - something that turns out to be useful in the lab for picking up biological molecules. But there are some manifolds that you don't want such as the nano-creases you get when you pinch a nano-surface.

KIM: It makes a very sharp groove on the service instead of wrinkles.

PALCA: And why can creases be a nano no-no? Well, because engineers would like to make foldable electronic computers that people could actually wear like a jacket.

KIM: For those structures, if they are creasing, than they can break the circuits.

PALCA: So Kim is trying to design folded surfaces that won't crease, even, when pinched. A few years, ago Kim decided he needed a new word to describe his work on wrinkles and crinkles and ridges and creases. So he decided to call them ruga structures. That's ruga spelled R, U, G. A, in case you're wondering. And if you're also wondering why ruga...

KIM: My daughter is actually a Latin major in PhD, and she suggested - why don't you use ruga?

PALCA: Ruga, it turns out, is the Latin word for wrinkle. Unfold science and the English language gains a new word - nice. Joe Palca, NPR News.

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