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UC Berkeley engineers invent ultra-thin chameleon-like skin

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MARCH 16, 2015

A team of UC Berkeley engineers published a study Thursday on the creation of an ultra-thin film that shifts color when flexed, inspired by the ability of chameleons to change color.

The team of UC Berkeley engineers who published the study — Connie Chang-Hasnain, Li Zhu, Jonas Kapraun and James Ferrara — used the fundamental elements of color and the human eye to develop a silicon film about a thousand times thinner than a human hair. The rows of tiny ridges on the film reflect light at different wavelengths, depending on how spaced out each ridge is from the others. The study was published Thursday in the journal Optica.

“The colors we see in objects are detected by the human eye when the white spectrum of light hits the surface (of an object),” Zhu, one co-author of the study and a fifth-year graduate student at UC Berkeley’s department of electrical engineering and computer science, said. “Depending on the object’s chemical architecture, the surface absorbs or reflects different wavelengths of light. Shorter waves that are reflected are seen as blue, and the longer waves are seen as red.”

According to Zhu, the spacing between the ridges is crucial because it determines which colors can be reflected off of the film — typically a function of the chemical composition of objects people see. When the space between the ridges is manipulated by flexing the silicon film, different wavelengths of light are reflected and detected by the human eye. Rather than changing the entire chemical makeup of a material, the team devised a way to manipulate its surface.

Coincidentally, research by scientists at the University of Geneva, which described how chameleons change color, was published just two days earlier.

The artificial chameleon skin can serve as an energy-efficient way to light up phone, laptop and e-reader screens. Typically, color displays for electronics require electricity as a power source. The chameleon film, which does not require power to change colors, will significantly decrease the amount of energy required by electronics.

Pieces of the chameleon film could also be used as sensors to monitor any structural changes that may occur in buildings, airplanes and bridges. If a building’s infrastructure or an airplane wing changes shape or structure, the chameleon film will shift colors, acting as an indicator of a potential disaster.

At the most basic level, the film can allow objects — as well as humans — to change color without the use of pigments or dyes, just as chameleons do.

“If you ask anyone, even people outside of the scientific realm, people think it’s extremely cool to be able to camouflage themselves,” Zhu said. “(The film) will allow our clothes to change color or make us invisible, just like in movies.”

Contact Jennifer Kang at [email protected] and follow her on Twitter @jennikang.

MARCH 17, 2015

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