Imagine a single pair of glasses with lenses that can be transparent or dark, and in shades of yellow, green or purple, all at the touch of a button.
Now, thanks to researchers at the University of Washington (UW), such glasses are a reality – made possible by a new material uniquely suited to the task: a low-cost sheet that changes colour and shade using almost no power.
Researchers led by Chunye Xu, research assistant professor of mechanical engineering at the University, created the lenses for the glasses by sandwiching a gel between two layers of electrochromic material.
The prototype glasses are powered by a watch battery that attaches to the glasses frame, and the wearer spins a tiny dial on the arm of the glasses to change colour or shade.
Applying a small voltage moves charged particles from one layer to another, and changes the transparency. Once the glasses are a certain tint they will stay that way without power for about 30 days. A single watch battery is able to power thousands of transitions, Xu said.
The prototype glasses change from dark blue to light blue. Xu and her colleagues have developed other adjustable lenses in red and yellow. In the future, they will layer sheets to create a range of colours in a single pair of shades.
“These are a little homemade,” Xu said of the prototype, a modified pair of lab goggles. She now plans to incorporate the lenses in more fashionable frames. Xu’s group has a number of patents filed on the technology and is exploring options for commercialization, but it will be a few years until the sunglasses show up on store shelves.
This research was funded by the UW’s Technology Gap Innovation Fund. Collaborators on the project are professor of mechanical engineering Minoru Taya and doctoral student Chao Ma.