By routing signals from helmet-mounted cameras, sonar and other equipment through the tongue to the brain, they hope to give elite soldiers superhuman senses similar to owls, snakes and fish.

Researchers at the Florida Institute for Human and Machine Cognition hope to turn fiction into reality by giving army rangers 360-degree unobstructed vision at night and allowing Navy Seals to sense sonar in their heads while maintaining normal vision underwater.

The device, known as "Brain Port", was pioneered more than 30 years ago by Dr Paul Bach-y-Rita, a University of Wisconsin neuroscientist.

Superior transmitter

Bach-y-Rita began routing images from a camera through electrodes taped to people's backs, discovering that the tongue was a superior transmitter.

A narrow strip of red plastic connects the Brain Port to the tongue, where 144 microelectrodes transmit information through nerve fibres to the brain.

Navy Seals may soon be able to
see through their tongues

Dr Anil Raj, the project's lead scientist, said instead of holding and looking at compasses and bulky hand-held sonar devices, the divers can process the information through their tongues.

In testing, blind people found doorways, noticed people walking in front of them and caught balls.

A version of the device, expected to be commercially marketed soon, has restored balance to those whose vestibular systems in the inner ear were destroyed by antibiotics.

Electronic sensors

Michael Zinszer, a Navy diver and director of Florida State University's Underwater Crime Scene Investigation School, took part in testing using the tongue to transmit an electronic compass and an electronic depth sensor while in a swimming pool.

He said: "You are feeling the outline of this image. I was in the pool, they were directing me to a very small object and I was able to locate everything very easily."

Underwater crime scene investigators might use the device to identify search patterns, signal each other and "see through our tongues, as odd as that sounds", Zinszer said.

Raj said the objective for the military was to keep Navy divers' hands and eyes free.

"It will free up their eyes to do what those guys really want to, which is to look for those mines and see shapes that are coming out of the murk."

Sonar

Sonar is the next step. A lot depends on technological developments to make sonar smaller - hand-held sonar is now about the size of a lunch box.

"If they could get it small enough, it could be mounted on a helmet, then they could pan around on their heads and they could feel the sonar on their tongues with good registration to what they are seeing visually," Raj said.

The research at the Florida institute, the first to research military uses of sensory augmentation, is funded by the US defence department.