A research team led
by Ali Javey, associate professor of electrical engineering and computer
sciences, 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, who is also a faculty scientist at the Lawrence
Berkeley National Lab. "The light from a flashlight is enough to generate
a response."
The researchers described their experiments in a paper
published this week in the journal Nature Communications. They 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," said Javey. "Curtains made of this material could
automatically open or close during the day."
Other potential applications include light-driven motors and
robotics that move toward or away from light, the researchers said.
Other co-authors include Xiaobo Zhang, study lead author and
former Ph.D. student in the Javey Lab, and researchers from the Berkeley Sensor
and Actuator Center.
The National Science Foundation and the Department of Energy
helped support this work.
Engineers have created a new light-reactive material made up
of carbon nanotubes and plastic polycarbonate. This video demonstrates
experimental "curtains" that are engineered to either open or close
in response to light.
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