In the eye of the beholder: contact lenses as displays and sensors.

• Author: Jean, Grace V.
• Position: INSIDE SCIENCE + TECHNOLOGY

The next time you look at a computer chip, imagine what might happen if the electronics were miniaturized and embedded into a contact lens. Scientists believe that the little plastic discs that hundreds of millions of people rely on to see clearer may one day serve military personnel and medical patients as information displays and health monitoring devices.

A research group at the University of Washington is developing "functional contact lens systems" that contain tiny sensors, radios, optoelectronic components and control circuits. The scientists are attempting to display computer-generated graphics on the lens without blocking the user's field of vision and to measure the lens wearers' biomarkers, or health indicators, in a non-invasive way.

"We're making a lot of progress," says electrical engineering professor Babak Parviz, the lead scientist for the research program.

Piggy-backing on advances made in the $2 trillion semiconductor industry, the team has fabricated prototype lenses using a technique developed in Parviz's lab.

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Traditional semiconductor fabrication processes employ high temperatures and corrosive gases to make components and embed them into substrates--a layer of silicon that is part of the wafer. The heat and chemicals are hostile to unconventional substrates made from flexible polymers--in this case, a plastic similar to the material found in hard contact lenses.

Because manufacturing the components directly onto a lens is impossible, the new process involves fabricating the subcomponents separately onto silicon-on-insulator wafers and other substrates first, and then employing a chemical process to allow the subsystems to self-assemble and implant themselves into the contact lens.

To the naked eye, these subcomponent devices--the miniscule biosensors, antennae, semiconductor circuit components and micron-scale light sources--collectively resemble a fine white powder. But each component is etched into different shapes to match its place on the contact lens system with metal interconnects. The team submerges the flexible transparent polymer substrate in a chemical liquid medium. As the components flow by, they fall into place like pieces of a puzzle. Alloys at the bottom of these "slots" lock them in.

Using this process, the team has fabricated contact lenses with light-emitting diodes, radio chips and antennae. "We have been able to show that we can beam in radio frequency and operate the light...