Forget blinds, an innovative new window that can quickly change opacity from cloudy to clear – or somewhere in between – with just a flick of a switch has been developed by a group of scientists from Harvard University.
Although tunable windows are not new, the smart window is different from old ones, which have relied on electrochemical reactions. Previous tunable windows are also quite pricey.
David Clarke, one of the developers of the tech, said their new tunable window takes advantage of geometry in order to adjust the transparency of a window. It is indeed a much cheaper option, he said.
What's amazing is that the change in transparency all happens in one second.
The specialized window is comprised of a sheet of glass or plastic, sandwiched between soft and transparent elastomers that have been sprayed with a coating of silver nanowires.
But the nanowires are actually too small to scatter light on their own, so Clarke and his colleague Samuel Shian applied an electric voltage to make it work.
By doing so, the nanowires on either side of the glass are excited and triggered to move toward each other, squeezing the soft elastomer.
The nanowires are placed unevenly across the surface, and so the soft elastomer also deforms unevenly. When that happens, light is scattered and the glass becomes opaque.
Shian said the tech is similar to a frozen pond.
"If the frozen pond is smooth, you can see through the ice," said Shian. "But if the ice is heavily scratched, you can't see through."
The roughness of the elastomer greatly depended on the electric voltage, the duo said. If you want a window that is totally opaque, you would have to apply more voltage than if you wanted a window that's only slightly clouded, and vice versa.
Clarke said because their tech is a physical phenomenon rather than a chemical-based reaction, it is a potentially cheaper and definitely simpler way to achieve tunable windows.
The duo's method also allows their tech to be scalable for bigger architectural projects, especially because the nanowires can be peeled or sprayed onto the elastomer.
Meanwhile, the team is working on incorporating thinner versions of elastomers. These would need lower voltages and are more suited for standard electronic equipment.
Harvard has filed a patent application on the tech. It is currently also engaging with potential licensees in the glass manufacturing industry.
The research is published is the journal Optics Letters, and was funded by National Science Foundation.
Photo : James O'Gorman | Flickr
