Thumper has seen the future.
Researchers at the University of Washington have created the prototype for a bionic contact lens — recently tested on rabbits — that includes light-emitting diodes, basic wiring for electronic circuits and even a tiny antenna. Future versions, the scientists believe, could serve as a flexible plastic platform for applications such as surfing the Internet on a virtual screen, immersing gamers in virtual worlds and monitoring patients’ medical conditions.
Babak Parviz, an assistant professor of electrical engineering at the University of Washington, said he and his collaborators began by thinking about contact lenses and their normal purpose of correcting vision. What if his group’s collective expertise in nanotechnology and microfabrication could transform the lenses into something else entirely?
Adding displays directly onto the lenses, visible to the wearers but no one else, could project critical information onto windshields for drivers or pilots or superimpose computer images onto real-world objects for training exercises. And with a wireless connection to the Internet, the lenses could allow bus or train riders to surf the Web on virtual screens suspended in midair or pave the way for gaming enthusiasts to immerse themselves in virtual worlds with no restrictions on their range of motion (although perhaps adding a further nuisance for fellow commuters).
A boon for mobile devices
If successful, the bionic lens could prove a huge boon for mobile-device manufacturers.
“One of the problems is that we can make the electronics smaller and smaller, and then the user wants to interface,” Parviz said. “A really tiny display is not useful.” But putting that display directly onto the user’s contact lenses would effectively solve the problem of size and allow personal electronics to continue shrinking.
Whether a future iPod will come equipped with a bionic contact remains to be seen — literally — but a lens with a basic display could be ready in the near future.
Parviz said the health care field also might benefit from the technology. “How do we constantly monitor someone’s health?” he said. “It turns out that a lot of indicators that tell if a person is healthy or not show up on the surface of the eye.”
A biosensor-equipped lens could provide a non-invasive way of gleaning that information and sending it on to a database or serving as a relay station for data or power from retinal implants designed to correct vision problems.
One of the first big obstacles for the team was resolving the fundamental incompatibility between the fabrication process for microchips and light-emitting diodes and the types of polymers used for contact lenses. To get around the issue, the researchers first constructed electronic circuits from ultra-thin metal layers — each only one-thousandth the width of a human hair — and fashioned diodes so small that nearly 100 could fit within an inch.
On the lens itself, the researchers created multiple receptor sites that each attracted a separate component by exploiting the same capillary forces that push water up through a plant’s roots. This microfabrication technique allowed the tiny parts to self-assemble on the surface of the lens and bind themselves together to form the different devices. Although circuitry covers much of the current prototype’s surface, Parviz said there should be enough room on the periphery of the lens to ensure that future nano-gadgetry wouldn’t obstruct a person’s view.
For the prototype, the group successfully integrated an antenna, tiny metal wires for an electronic circuit, and red light-emitting diodes onto the lens surface. Harvey Ho, a former graduate student in Parviz’s lab, presented the research Thursday at the Institute of Electrical and Electronics Engineers’ international conference on Micro Electro Mechanical Systems in Tucson, Ariz.
Focusing on image quality
Some scientists have been less gung ho. Daniel Palanker, a retinal implant expert at Stanford University, questioned the ability of a display generated by the contact lens to produce a sharp image on the retina of its wearer’s eye, noting that the normal focal distance for seeing objects clearly is about 25 centimeters in front of a person’s eye.
But Glenn Chapman, a professor in the School of Engineering Science at Simon Fraser University in Burnaby, British Columbia, said researchers could overcome that obstacle by precisely adjusting the angle of incoming light emitted by diodes on the contact lens.
Assuming the light beam is high-quality, he said, correcting the beam's incoming angle could make up for the cornea's lack of focusing ability and instead allow the transparent crystalline lens behind the eye's iris to focus the image onto the wearer's retina. Of course, contact-wearing rabbits won't be able to tell researchers when they've hit upon the right angle to produce a crisp image, Chapman said, but an artificial eye overlaid with the lens could do the trick.
Parviz said his team also will try to pair microlenses to each pixel in a display created by the contact lens, hopefully manipulating the image and changing its perceived location in such a way that the viewer would have the feeling of seeing an in-focus picture suspended in midair. But he agreed that the challenge will be a complicated one. "It's unprecedented," he said. "No one has ever tried to form an image right on the surface on the cornea."
As for the microfabrication process, Chapman said he was impressed with how the self-assembly technique allowed the University of Washington researchers to basically float into position metal pieces that normally don't adhere well to plastic surfaces. The technique had been developed previously by Parviz and others, he said, "but it's a nice application of it."
And with further advances in the microfabrication field, Chapman said, the potential is "very high" for wires that are essentially invisible to the human eye and for even tinier organic light-emitting diodes.
'Like a normal contact lens'
If size isn’t necessarily a limitation, adequate power could be. Parviz said his group is now working on the issue of how to run displays or biosensors without the need for awkward batteries. So far, the prototype’s lens-mounted antenna has shown promise in collecting radio frequency waves and turning them into useful energy.
If all goes well, putting in or taking out the bionic lens should be as easy as popping a regular one in or out, he said. “It should feel like a normal contact lens. It should be completely smooth against the surface of the eye.”
Which isn’t to say the lens is inconspicuous. “If you look into the rabbits’ eyes, you would notice that something is going on,” Parviz said.
Nevertheless, the rabbits tolerated the bionic lenses well during their 20-minute fittings, though none of the systems have yet been switched on. The group has yet to seek permission for the necessary safety trials in humans.
If safety and engineering issues are addressed, future iterations could perhaps be engineered to camouflage the circuitry, thus sparing bionic lens-wearing commuters the stares of passersby swearing they’d just seen the Terminator or a visor-less Geordi La Forge from “Star Trek: The Next Generation.”
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