Researchers at Harvard are developing the next generation of windows that utilize nanotechnology to transition between clear and cloudy with the flip of a switch. Ben Gruber reports.
Now you see the Lego man and now you don't. It's a small demonstration of a technology that could have a huge impact on how windows are made. Windows that can change opacity or color already exist but rely on electrochemical reactions that are expensive to produce, especially on a commercial scale. (SOUNDBITE) (English) DAVID CLARKE, PROFESSOR OF MATERIAL SCIENCE, HARVARD UNIVERSITY, SAYING: "They are all very effective, although I think ours is even more effective. But the big problem is how you create large areas, windows, and the cost." David Clarke and Sam Shian, both from Harvard's school of engineering, have figured out a way to produce windows that go from clear to cloudy with a flip of a switch in a way that is both cost effective and commercially scalable. The team sprays nanowires on to both sides of an elastomer rubber and then adhere it to glass. (SOUNDBITE) (English) DAVID CLARKE, PROFESSOR OF MATERIAL SCIENCE, HARVARD UNIVERSITY, SAYING: "When you apply a voltage to them relative to some background there is an attractive force between the nanowires and the substrate that deforms the elastomer. Elastomer rubber is very soft and so the surface becomes rough, and it is that roughness that scatters light." And the more voltage applied the cloudier the window becomes as the nanowires deform the surface of the rubber further, scattering more light. Shian says that in theory scaling this technology should be commercially viable because the reaction is physical rather than chemical. (SOUNDBITE) (English) SAM SHIAN, MATERIALS SCIENTIST, HARVARD UNIVERSITY, SAYING: "When we are talking about windows we are talking about several feet by several feet. There are other things that you have to consider. For example, the conductive theory of this charge towards the surface, we are talking from small to large so these kind of things need to be optimized." And once optimized, cheap windows that can frost over in a second will become a reality…while curtains and blinds may become a thing of the past.