Most will be familiar with photochromic lenses that darken when exposed to UV light, but now a researcher at the University of Connecticut has developed lenses that can quickly switch color based on the amount of voltage passed through them. While sunglasses manufacturers are expected to employ the technology to create color-changing sunglasses, it has also apparently captured the attention of the U.S. military who see it as a way to potentially assist soldiers to see clearly in rapidly changing environments.
Unlike transition lenses that use photochromic film or a sheet of polymers that change color when light hits them, the color changing technology developed by Greg Sotzing, professor of chemistry in the College of Liberal Arts and Sciences and a member of UConn's Polymer Program, uses electrochromic lenses that are controlled by an electric current passing through them. So while the lenses themselves don't react to light, the electric current could be triggered by a stimulus, such as light.
Sotzing likens the lenses to double pane windows with a gap between them. This gap is squirted full of a mixture of polymers that harden to create the lens. He adds that the mixture of polymers used in his lens creates less waste and in less expensive to produce than previous mixtures, opening up the technology for use in items such as sunglasses that are commonly misplaced.
Because the material changes color as fast as electricity passes through it, which is virtually instantaneously, Sotzing says it also has applications for the military. Whereas a soldier may currently need to physically change the lenses in their goggles when emerging from a dark interior into bright sunlight, the electrochromic lenses could automatically alter their color instantly.
Sotzing is looking to develop this and other ideas when he begins a one-year sabbatical at the U.S. Air Force Academy in August.
The University of Connecticut has a patent pending for the technology and has started a company, Alphachromics Inc., which is currently in talks with sunglasses manufacturers - surely color-changing rose-colored glasses can't be too far off. As it can be used to create variable color displays and films, Alphachromics is also looking at the potential for energy-saving windows and custom fabrics made using the technology.
The electrochromic lens technology is detailed in a paper published in the Journal of Materials Chemistry.