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. “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.”
The contact lens has both a wireless receiver and a display built into it. The researchers created the electronic lens with two main purposes in mind. 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 the person to see the real world. It would be a sort of augmented reality. Soldiers, for example, 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.
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. According to the researchers, many indicators of health can be monitored from the surface of the eye. The live cells on the eye 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.
The researchers describe how they created a lens with 16 working LEDs. The lens was made from a polyethylene terephthalate substrate which was covered with metal wires for connecting the LEDs. The researchers used chemicals to carve out circular indentations in which the LEDs would be placed. Because electronics are made at temperature high enough to melt plastic, the LEDs were fabricated separately and transferred to the lens. The device was then coated with a biocompatible material and shaped.
One of the next steps for the team will be to increase the number of LEDs on the lens to a couple hundred, in the hope of making a viable display. Right now, the LEDs are about 300 micrometers in diameter, which obviously limits the number of them that can be put on a lens. LEDs this size tend to break during the lens-shaping process, so the researchers will try to shrink them to 30 micrometers which could make a possible lens display of a few hundred pixels. Also, the team needs to make sure that the electronic lens is safe for the eye when turned on. “It’s a functioning circuit. It could generate some heat. We need to take all the possible precautions to make sure this is safe,” says Parviz.
Whether used as a display or medical sensor, the new lens may open up new possibilities for the human eye.