Carbon nanotube-coated material moves when exposed to light

Who needs smart windows when you can have smart curtains? University of California-Berkeley researchers have created a material that can bend or straighten when exposed to light, no batteries required. It could be integrated into objects like curtains or even robots to add an automatic response to light. The Berkeley team published their work in Nature Communications this week.

“The advantages of this new class of photo-reactive actuator is that it is very easy to make, and it is very sensitive to low-intensity light,” associate professor Ali Javey said in a release. “The light from a flashlight is enough to generate a response.”

The researchers created a series of small “curtains” by layering carbon nanotubes on top of a disc of flexible plastic. The nanotubes, which are rolled up tubes of carbon atoms that are highly efficient at absorbing light, were exposed to a light source. They turned the light into heat and passed it on to the plastic disc. The heat caused the plastic to bend while the nanotubes maintained their shape, leading the disc to bend.

The size or orientation of the nanotubes can be tweaked to coax the discs to respond to different wavelengths of light. The plastic can also be altered to give its resting state a flat or curled shape.

“We envision these in future smart, energy-efficient buildings,” Javey said in the release. “Curtains made of this material could automatically open or close during the day.”