Rose tinted glasses

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.