Researchers in Finland and the US have developed and tested a prototype contact lens that could provide the wearer with a real time hands-free display.
The researchers from the University of Washington and Aalto University, Finland, have constructed a computerised contact lens and demonstrated its safety by testing it on live eyes. At the moment, the contact lens device contains only a single pixel but the researchers see this as a "proof-of-concept" for producing lenses with multiple pixels which, in their hundreds, could be used to display short emails and text messages right into the eye.
The contact lens consists of an antenna to harvest power sent out by an external source, as well as an integrated circuit to store the energy and transfer it to a transparent sapphire chip containing a single blue LED.
The device could overlay computer-generated visual information on to the real world and be of use in gaming devices and navigation systems. It could also be linked to biosensors in the user's body to provide up-to-date information on glucose or lactate levels.
One major problem the researchers had to overcome was the fact that the human eye, with its minimum focal distance of several centimetres, cannot resolve objects on a contact lens. Any information projected on to the lens would probably appear blurry. To combat this, the researchers incorporated a set of Fresnel lenses into the device; these are much thinner and flatter than conventional bulky lenses, and were used here to focus the projected image on to the retina.
After testing the contact lens in free space, it was fitted to the eye of a rabbit, under the strict guidelines for animal use in the laboratory, to evaluate the effect of wearing the contact lens on the cornea and the body in general. In addition to visualising techniques, a fluorescent dye was added to the eye of the rabbit to test for any abrasion or thermal burning.
"We need to improve the antenna design and the associated matching network and optimize the transmission frequency to achieve an overall improvement in the range of wireless power transmission,ö said Professor Babak Praviz of the Department of Electrical Engineering, University of Washington in Seattle."Our next goal, however, is to incorporate some predetermined text in the contact lens."
This article was first published in our sister publication EE Times Europe.
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