(I can see kwaps, zog military, etc. getting interested in this kind of technology ...)

Your life will be flashed before your eyes: Prototype contact lenses that include LEDs and circuits could become a tiny personal display

Babak Parviz wears contact lenses. But he's not yet using the new contact lenses he's made in his Seattle laboratory. Containing electronic circuits, they look like something from a science fiction movie. He's now going to add some extremely small light emitting diodes (LEDs), helping turn his prototype contact lenses into a sophisticated personal display - the tiniest one possible.

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So far, he's shown that high-performance circuitry including microLEDs can be incorporated on to transparent, thin, flexible plastic substrates. The circuits involve making metal layers a few nanometres thick linked to LEDs that are about one third of a millimetre across. A microfabrication technique known as self-assembly relies on capillary effects to bring together pre-shaped pieces of circuit.

The prototype contact lens - which will eventually contain LEDs - has yet to be powered up. That key step, says Parviz, is several months off. "We're looking at two different ways to transmit power. One is radio frequency power transmission. We need antennae on these contact lenses anyway because we need to transmit data to them. The other way we're looking at right now is to incorporate photovoltaic [solar] cells."

Power isn't the hardest problem. A contact lens sits directly on the surface of the eye, much too close for the eye's lens to focus on. "To create the focused image we have to manipulate the light rays," says Parviz. "You can create a focused image if you use laser instead of LEDs."

If shining very low power diode lasers on to the retina seems risky, then microLEDs might be the answer. These provide diffuse light and, to make them work, Parviz might integrate an array of individual micro-lenses into the contact lens. "If the pixel [the microLED] is close enough to the micro-lens, it will generate a virtual image that could be 30cm or more away from the surface. Our eyes can focus on this now."

All this raises questions of biocompatibility: the electronics in the contact lenses must not harm the eye. If that's assured, then the idea of a fully functional wireless display on a contact lens might seem, at first, to have many uses.

Parviz talks about augmented reality, such as superimposing text messages or direction arrows on your view of the world. But even trivial applications will require a high-resolution display. So his next step is to demonstrate a programmable wireless contact lens with a few pixels - perhaps eight - that's safe to wear. Since his work became widely known, Parviz has received emails from people wanting to test the contact lenses, while others have proposed ideas. He's also had emails from those with vision problems, an area he hopes to help with.

http://www.guardian.co.uk/technology/2008/jul/03/led.contact.lenses