New smart curtains move in response to light

Scientists have designed new smart light-activated curtains that move in response to light, without the need of batteries.
A research team led by Ali Javey from the University of California, Berkeley, layered carbon nanotubes - atom-thick rolls of carbon - onto a plastic polycarbonate membrane to create a material that moves quickly in response to light.
Within fractions of a second, the nanotubes absorb light, convert it into heat and transfer the heat to the polycarbonate membrane's surface.
The plastic expands in response to the heat, while the nanotube layer does not, causing the two-layered material to bend.
"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," said Javey.

"The light from a flashlight is enough to generate a response," said Javey.

The researchers were able to tweak the size and chirality - referring to the left or right direction of twist - of the nanotubes to make the material react to different wavelengths of light.
The swaths of material they created, dubbed "smart curtains," could bend or straighten in response to the flick of a light switch.
"We envision these in future smart, energy-efficient buildings. Curtains made of this material could automatically open or close during the day," said Javey.
Other potential applications include light-driven motors and robotics that move towards or away from light, researchers said.

The findings were published in the journal Nature Communications.