Friday, January 25, 2008

How to Build a Bionic Eye

Researchers have created an electronic contact lens that could be used as a display or a medical sensor.

By Kate Greene

The eyes have it: Researchers built a biocompatible contact lens with working LEDs, shown here. They hope that future versions of the lens can act as a biomedical sensor, or provide a display that is superimposed on a person’s field of view. Credit: University of Washington

People don't think twice about wearing a Bluetooth headset to have conversations on their cell phones. Well, one day it might not be unusual to wear a contact lens that projects the phone's display directly onto the eye. Researchers at the University of Washington have taken an important first step toward building contact lenses that could do just that. By incorporating metal circuitry and light-emitting diodes (LEDs) into a polymer-based lens, they have created a functional circuit that is biologically compatible with the eye.

"If you look at the structure of a lens, it's just a simple polymer," says Babak Parviz, professor of electrical engineering at the University of Washington. A number of researchers are putting electronics into polymers to build flexible circuits or displays, for instance. "What we realized was, we can make a lot of functional devices that are really tiny, and they can be incorporated into a contact lens to do a lot more than just improve vision," Parviz says.

The team created the electronic lens with two main purposes in mind, he says. One of the goals was to see if it would be possible to build a heads-up display that could superimpose images onto a person's field of view, while still allowing her to see the real world. It would be a sort of augmented reality, explains Parviz. (See "TR10: Augmented Reality.") Soldiers could use the technology to see information about their environment, collected from sensors. Or civilians could use the electronic lens as a cell-phone display, to see who is calling and to watch videos during a commute, although these goals are long term, he says.

Another possible application is to use the lens as a sensor that could monitor chemical levels in the body and notify the user if they indicate signs of disease. Although Parviz won't go into details about the specific sensors that his team is making, he explains that many indicators of health can be monitored from the surface of the eye. The live cells on the eye, he says, are in indirect contact with blood serum, which contains biomarkers for diseases. If a sensor designed to pick up these biomarkers was built into a lens, then doctors could have a completely new, noninvasive tool for disease tests. In addition, the lens could continually monitor changes over time, providing a more complete view of a person's health.

Admittedly, these applications are years away. But Parviz and his team have laid the foundation for the work. In a paper presented at the International Conference of Micro Electric Mechanical Systems in Tucson, AZ, last week, the researchers describe how they created a lens with 16 working LEDs. The lens was made from a polyethylene tetraphthalate substrate--the kind of plastic used in beverage bottles--which was covered with metal wires for connecting the LEDs.