The July issue of Saga has an article by Roger Highfield called "Suck it and see" about a device named BrainPort, where placing a "lollipop" on the tongue, linked by wire to a video camera incorporated in dark glasses, enables blind persons to have some ability to "see".
It sounds like science fiction but apparently it works. The article says that the lollipop is a "400-electrode one-inch square sensor array". The tongue is very receptive to sensations. Wicab, who are based in Wisconsin, is the company behind the development, which is based on the research of the late neuroscientist Paul Bach-y-Rita.
This is a video showing the product in use.
The prototype has been tried out with considerable success. After 20 hours of training, 16 blind and 4 sighted but blindfolded persons were able to walk along a 40-foot obstacle course. It has been described as a low-resolution version of normal sight.
So how does it work ? The visual image in pixels translates to transducers applied to the tongue. Operating the lollipop feels like Champagne on the tongue, with white areas of the image creating strong pulses, black areas none, and grey in between. The first Briton to try the BrainPort, Lance Corporal Craig Lundberg, is said in the article to be able to "read words, identify shapes and walk unaided."
I looked of course for a patent specification, and Tactile input system, published in 2005 in the "world" system is clearly relevant.
Only one patent was cited against it as relevant in a later published search report, an American patent published in 1989. I was surprised to find it cited, as while it too uses tactile means, it does so in a different organ and to deal with a different disability: it's Jeffrey McConnell's Method and apparatus for communicating information representative of sound waves to the deaf. The main drawing is shown below.
The Wicab invention has not (yet) been granted rights. In Europe it has been "deemed withdrawn", see the official status entry, which mentions other "prior art". The US PAIRS status database states that the last "action" has been "mail non-final rejection", as of the 25 March 2011. A 11 page document available in that database explains why the examiner objected to the patent claims and the drawings: ask your local patent depository library if you are interested in seeing it.
The Wicab site gives more detail on this promising invention. The company will need permission to begin to market what is still a prototype both in the USA and in Europe.