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Windows that can
change opacity or color already exist but rely on
electrochemical reactions that are expensive to manufacture,
especially on a commercial scale.
"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," said Professor David Clarke, a material
scientist at Harvard.
The scientists have figured out a method to produce windows that
go from clear to cloudy at the flip of a switch in a way that is
both cost effective and commercially viable, according to a
study they published in the journal Optical Letters.
The team uses elastomer rubber coated with nanowires that
adheres to glass to scatter light when voltage is applied.
"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," said Clarke. "Elastomer
rubber is very soft and so the surface becomes rough, and it is
that roughness that scatters light," Clarke added.
Samuel Shian, an author on the study, believes scaling this
technology should be commercially viable because the reaction is
physical rather than chemical. Current chemical-based
controllable windows use vacuum deposition to coat the glass, an
expensive process that deposits layers of a material molecule by
molecule.
But to transition this technology to the real world will take a
bit more fine tuning in the lab, according to Shian.
"When we are talking about windows we are talking about several
feet by several feet...we are talking from small to large, so
things need to be optimized," he said.
One obstacle is developing a thinner elastomer that would
require lower voltages to deform.
Harvard has filed a patent application on the technology.
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