User-controlled tinted sunglasses on the horizon

Current photochromic lenses provide a convenient two-in-one answer for those who need prescription lenses, for both indoors and out, but researchers are working on an even better solution.

These special lenses are designed to use the sun’s UV rays to turn the glass from clear to tinted—but the change isn’t instantaneous, so users step outside and squint in the harsh sunlight, or move indoors and have to wait for the lenses to adjust. Most modern car windshields use UV-filtering glass that prevents the lenses from darkening completely. Due to too much ambient UV light at high altitudes causes the lenses to remain darker for longer, even indoors.

A group of researchers at the Georgia Institute of Technology in Atlanta has developed a polymer coating for glass that can change the lens colour instantly with a small, user-controlled electrical current. Their work has been published in the American Chemical Society’s Applied Materials & Interfaces.

“Our technology is fully user controlled. So the lenses can change their colour, going from dark to clear, just by pushing a button,” says Anna Österholm, a research scientist in Georgia Tech’s School of Chemistry and Biochemistry.

The polymer coating uses electrochromic polymers (ECPs)—or polymers that change color when you apply a potential or a current. The material also allows for a wide spectrum of colour options for the coating, based on the weight compositions of the mixtures.

The polymer technology has a wide range of possible applications – it can be printed or sprayed onto large-format applications like billboards, for example.“Anything that you would want to have change color at the push of a button would be an application for these”

The researchers can’t promise a definitive timeline for when this technology will reach consumers, but they say it is close to moving out of the lab and becoming a reality. “It’s at that point right now where prototypes can be made and tested,” Reynolds says in the video.