Seattleites are known for the amounts of sunglasses they buy. They're the type of people who buy a new pair at the first sign of light each spring, wear them on and off during the summer, lose them in the fall, and start the process all over again the following year.

Now, researchers at the UW have developed a pair of glasses that might be worth holding onto for a bit longer than Seattle's sunny season.

A prototype of these smart sunglasses, which have chameleon-like lenses that change both colors and shades, were unveiled early this month in Chicago at the American Chemical Society's 233rd national meeting.

The glasses, which are produced using a cheap and power-efficient sheet, can adapt to the environment at the press of a button and can be used in a wide array of lighting situations: outdoors, in low light and inside a car.

Chunye Xu, research assistant professor of mechanical engineering at the UW, had quite a bit of light to shed on the subject of the new glasses. Her prototypes, developed in collaboration with professor of mechanical engineering Minoru Taya and doctoral student Chao Ma, currently utilize shades of blue when adapting to environments. There are also models that work with red and yellow tints.

"We're working on a pair right now that can change to be any color you like," Xu said.

The glasses would not be limited to red, blue or yellow, but could change to any color necessary at a given time. This would involve using layered lenses with different sets of sheets that will involve the primary colors, Xu explained.

"The change can be really quick, too, or any speed you like," she said. "It works kind of like a television dial, so changing the shade would be like changing the volume on your TV."

Sophomore engineering student Kurt Brendley supports the new invention.

"I know I'm the type of person that goes through two or three pairs of sunglasses in a year because I feel little attachment to them, but these glasses would be great when I go out biking around town," he said. "I can't wait to see all the goofy designer frames they use for these things in the future."

The glasses that have been developed so far use a small battery linked to the frame, which controls lenses created with a special gel sandwiched between electrochromic material.

"The glasses use a very small amount of power," said Xu. "So, therefore, the ones we've tested have a really long battery life and can last for years."

Different levels of electrical current alter the transparency of the electrochromic material.

Unlike other technology on the market or in development that uses inorganic oxides, these sunglasses utilize organic oxides that are cheaper to produce and "have a memory function that maximizes the energy efficiency," Xu said. The glasses can remain a desired shade for several weeks without power, she added.

"So far we have tested many transitions ... using different environments so we can see comfortably under UV light or indoors," Xu said. "These active sunglasses are great because they're both energy efficient and fit many environments."

The prototype shown at the ACS meeting was an altered pair of lab goggles, but Xu is currently working on patents for the sunglasses and hopes to have them on the market in the next few years, with much more fashionable frames available.

Reach reporter Guy Keltner at news@thedaily.washington.edu.