Magnet and glue turn tongue into joystick

• 17:04 29 June 2009 by Tom Simonite

Video: The tongue drive control system is being trialled by spinal injury patients

A headset that makes it possible for a person to precisely control a wheelchair or computer using only their tongue has begun trials with spinal injury patients in the US. The "tongue drive" could also give astronauts a third hand in difficult situations such as spacewalks.

The device works by using two sensors to track a 5-millimetre-wide magnet attached to the tip of the user's tongue. The sensors – embedded in a wireless headset – read the fluctuations in the strength of the magnetic field as the tongue moves and transmit the signals on to a computer, where they are interpreted and acted upon.

By moving the tongue in predefined patterns, the user can steer a cursor on a screen, direct a wheelchair, or switch on a TV, for example.

Spinal damage

The system is being developed by electrical engineer Maysam Ghovanloo and Xueliang Huo at Georgia Tech University, Atlanta.

After tests by able-bodied users, the latest prototype is now being trialled by the kind of people the gadget is intended for: spinal injury patients at Shepherd Center rehabilitation hospital, also in Atlanta.

In the US alone there are 250,000 people with spinal cord injuries, and more than half need an alternative way to interact with the world due to damage that restricts the use of their arms and hands, says Ghovanloo.

Sip and puff

Sufferers do have some options already: "sip and puff" devices operated by blowing or sucking on a straw held in front of the mouth, and extended headrests with embedded buttons operated with the head, are currently the most popular systems.

But the tongue-drive system can accept a wider variety of commands, and can be less conspicuous, says Ghovanloo. "Some don't like their sip and puff because it sits right in front of their face, and is like a signal of their disability," he told New Scientist. "Our design can be made less conspicuous."

The tongue's precision, and the fact it doesn't easily get tired, are also advantages, he adds.

Because of the risks of accidentally triggering the system as the tongue moves up and down during speech, commands must only use sideways movements. Commands can also be set to switch off and turn on the system when not needed – while eating, for example.

Tongue 'rings'

For now, the magnet is attached to a person's tongue using surgical adhesive. But Ghovanloo has had magnetic tongue piercings made that he says should appeal to long-term users.

The electronics inside the headset could also be fitted into a smaller space, he says, and talks have begun with a dental expert about installing them into a plastic retainer that fits inside the user's teeth.

A spin-off project has recently begun, to investigate how people with full use of their hands may benefit from the interface. "We want to find out if it is possible to give a task to your tongue as you're doing something else with your fingers," says Ghovanloo.

If it is, tongue interfaces could be of use to people in complex situations like astronauts or pilots, or even computer gamers.

Reaction times may be faster using the tongue than a finger, he adds. The neural pathway between the brain and tongue doesn't pass through the spinal cord, so is shorter than that between brain and finger.

The latest prototype was presented last week at the Rehabilitation Engineering and Assistive Technology annual meeting in New Orleans.

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