A new nano-material developed by engineers from the University of California, Berkeley, could lead to smarter and more efficient management of a building’s window fixtures and lighting requirements.
The composite material consists of a plastic polycarbonate membrane with a layer of carbon nanotubes a mere atom's span in thickness covering its surface. When the material is exposed to light, the nanotubes absorb its energy almost instantaneously before transforming it into heat which is conveyed to the surface of the underlying plastic membrane.
In response to the subsequent rise in temperature, the plastic membrane expands, yet the layer of carbon nanotubes remains fixed in its dimensions. This pair of contrary responses in the layers of the composite material compels it to warp or bend swiftly following exposure to light.
The light-sensitive material can be used as a fabric for the manufacture of "smart" curtains which are capable of adjusting themselves automatically in response to weather conditions without relying on either internal batteries or external power sources. The curtains can either contract or extend in response to levels of light exposure, closing and opening of their own accord depending on the time of day.
Ali Javey, a faculty scientist from the Lawrence Berkeley National Lab led the UCB team of engineers in the development of the material. He envisages the curtains playing a prominent role in the smarter, energy-efficient buildings of the future.
According to a paper published by Javey and his team in the science journal Nature Communications, they have already enhanced the material's sensitivity by fine-tuning the size and twist parameters of the carbon nano-tubes, enabling it react to a broader range of wavelengths of light.
The chief advantages of this new type of photo-reactive material include its ease of fabrication as well as its heightened sensitivity to modest levels of light. Javey claims that exposure to a level of light as mild as that generated by a flashlight is enough to trigger a palpable response in the material.
The researchers say the potential of the material extends well beyond its use in smart curtains, pointing to applications including light-driven motors and automated devices which are drawn to or repelled by sources of light.