‘Smart’ sunglasses will allow wearers to instantly change the color of their lenses to any hue of the rainbow almost instantly by tuning a tiny electronic knob in the frame. "Through polymer chemistry, we’ve developed lenses that aren’t like anything else on the market," said Chunye Xu, a chemical engineer at the University of Washington and associate director of the University’s Center for Intelligent Materials and Systems (CIMS), who are developing the lenses. They described their research at the 233rd national meeting of the American Chemical Society, held in March in Chicago. The lenses feature a unique type of electrochromic polymer that has the ability to change levels of darkness and color in the presence of an electric current. Researchers have been developing electrochromic polymers for decades, but Xu said her lab is one of just a few using the technology to develop improved eyewear. Xu has developed a prototype of the eyewear; powered by a tiny battery, its shades currently resemble a pair of laboratory goggles with a button attached to the frame. Turning the button activates the battery and dials the desired color. In laboratory demonstrations, Xu has shown that the lenses can switch from transparent to blue, plus various shades in between, at the flip of a switch. The glasses require power only during switching, to save energy and prolong battery life. Like regular sunglasses, they can be coated with a protective layer to block ultraviolet light. Ultimately, the sunglasses can be made to resemble the size and shape of regular sunglasses and should cost about the same, Xu said. But she said a practical version won’t be available to consumers for another year or two. So far, Xu and her associates have produced the electrochromic polymers in red, blue and green. By combining the polymers of different colors into multiple layers and supplying different levels of current from the batteries in the sunglasses, a wide variety of different colors can be produced in the lenses, Xu said. Her lab has filed several patents related to the color-changing glasses. Funding for the study was provided by the University of Washington. For more information, visit: www.washington.edu