In the future, contact lenses may provide a new way of looking at things. Engineers at the University of Washington have combined a flexible, biologically safe contact lens with an imprinted electronic circuit. The device contains an electronic circuit, as well as red light-emitting diodes for a display.

“Looking through a completed lens, you would see what the display is generating superimposed on the world outside,” says Babak Parviz, an assistant professor of electrical engineering who heads a multi-disciplinary group of researchers who are developing electronics for contact lenses. “The prototype contact lens does not correct the wearer's vision, but the technique could be used on a corrective lens.”

There are many possible uses for virtual displays. For instance, drivers or pilots could see a vehicle's speed projected onto the windshield. Video game companies could use the contact lenses to completely immerse players in a virtual world without restricting their range of motion. And, for communications, people on the go could surf the Internet on a midair virtual display screen that only they would be able to see.

“Ideally, installing or removing the bionic eye would be as easy as popping a contact lens in or out,” claims Parviz. “And, once installed, the wearer would barely know the gadget was there.”

Building the lenses was a challenge because materials that are safe for use in the body, such as the flexible organic materials used in contact lenses, are delicate. Manufacturing electrical circuits, however, involves inorganic materials, scorching temperatures and toxic chemicals.

Parviz and his colleagues built the circuits from layers of metal only a few nanometers thick. They constructed light-emitting diodes one-third of a millimeter across. Then, they sprinkled the grayish powder of electrical components onto a sheet of flexible plastic.

The shape of each tiny component dictates which piece it can attach to, a microfabrication technique known as self-assembly. Capillary forces—the same type of forces that make water move up a plant's roots, and that cause the edge of a glass of water to curve upward—pull the pieces into position.

“There is a large area outside of the transparent part of the eye that we can use for placing instrumentation,” Parviz points out. “Future improvements will add wireless communication to and from the lens.” Eventually, Parviz and his colleagues hope to power the device using a combination of radio-frequency power and solar cells placed on the lens.