Video: Tongue piercing lets you steer a wheelchair
Dexterous, sensitive and precise, it’s the ultimate hands-free device – no wonder the tongue is at the heart of a new generation of computer controls
LISTEN to Maysam Ghovanloo and you’ll soon be convinced that your tongue isn’t living up to its potential. As sensitive as your fingertips and as flexible as an octopus’s tentacle, this unsung organ makes a handy fifth limb, says Ghovanloo. “It’s just so natural,” he says, before gluing a pea-sized magnet to the tip of my tongue and passing me a headset. “With the tongue, you can touch every tooth in your mouth, without thinking about it, without training, focus or concentration.” To prove it, the engineer has spent a decade developing a tongue-based device as an all-purpose replacement for the mouse.
Called the Tongue Drive, it is already used by and control phones. Soon it will help to reveal the tongue’s intricate dance within the mouth while we speak, opening up an invisible world for speech therapists treating people with brain injuries. Yet its potential, Ghovanloo believes, extends far further. Like an extra limb, the tongue could , gadgets or even an oral version of Google Glass while our hands are busy with other tasks. “With the tongue, you just go ahead and do it,” says Ghovanloo. “It’s instinctive.” And if having to put a small ceramic disc in your mouth puts you off, never fear: engineers have come up with other ways to let your tongue do the work, magnet-free.
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I’m at at the Georgia Institute of Technology in Atlanta, trying to control a cursor on a smartphone’s screen. As I move my tongue, the magnet alters the magnetic field around my head and the changes are detected by sensors on the headset. I have already trained the system to recognise my commands – touching my tongue to a right molar, for instance, moves the cursor left. But it’s like learning a new language: I have to think about what I want to do then translate it into the language of the tongue. Soon, though, the cursor is gliding smoothly across the screen. I check the weather, scroll through some apps and dial a number. “This is fun,” I tell myself. “In a week, I’ll be fluent.” Then the magnet falls off.
Most of us don’t give our tongues a second thought. We don’t have to. Richly supplied with nerves that link it directly to the brain, this slippery minion responds instantly to every unconscious command. That’s why you can lick an envelope, sing and eat spaghetti, all without thinking. It is also incredibly fast and tireless, says Maureen Stone, a physiologist at the University of Maryland, who studies the tongue’s movements.
Precision instrument (Image: Helge Sauber/Plainpicture)
Yet what makes this organ truly unique is not its speed or stamina, but its precision. Though it evolved to aid eating, the human tongue has adapted to the complex movements required for speech. As a result its eight muscles are controlled by a nerve network that is denser and than in other mammals, giving us incredibly fine control. “You have as many degrees of freedom in your tongue and lips as you do in your hands and fingers,” says Ghovanloo.
Sensory alchemy
Ghovanloo began to think about enlisting tongue power in the 1990s after he read at the University of Wisconsin-Madison. It described a process that could help blind people “see” by feeding electrical impulses from a video camera to an array of electrodes placed on the tongue. In a kind of sensory alchemy, the tongue’s nerves detected the impulses and the user’s brain translated them into an image (see “Taste the World“).
This got Ghovanloo thinking. The tongue is sensitive, but agile too. Could it convey the brain’s commands when the rest of the body is paralysed? In 2005 he patented a simple control system: sensors detect motion of a magnet on the tongue and use it to control a wheelchair. He called it the Tongue Drive. “It is the ultimate hands-free device,” says Jason Disanto, one of the Tongue Drive’s testers, who was paralysed in a diving accident in 2009.
Now Ghovanloo’s invention is finding new roles. At Georgia State University in Atlanta, people who have had limbs paralysed as a result of stroke will be able to control robotic limbs with the device. If they can do this, the thinking goes, it just might help them to retrain their brains to move those limbs again. “We’re hoping that the neurons that fire together, wire together,” says researcher Andrew Butler who is working on the project.
A few kilometres north at the Shepherd Center, a hospital for treating brain and spinal cord injuries, speech-language pathologist Kimberly Wilson hopes Ghovanloo’s device can help solve a mystery. As part of her work to rehabilitate injured soldiers, many of whom have brain injuries, Wilson teaches them to speak again. But this is difficult when you cannot see what a patient’s tongue might be doing wrong. The Tongue Drive will allow her to visualise tongue movements, so she can spot mistakes and correct them. “I see so much promise in this technology,” she says.
Ghovanloo has spent nine years shrinking the headset from a clunky baseball helmet to a circuit small enough to fit inside the mouth like a dental brace. Yet major challenges remain. The Tongue Drive is limited to six simple commands, including left and right, but Ghovanloo aims to make the cursor move fluidly with the tongue and treat the entire bony palate as a mouse pad. A more serious problem is safety: if, say, a burst of radio waves from a shop’s RFID reader disabled the device, a user would be helpless. To prevent this, and to get regulatory approval for selling the drive, Ghovanloo is planning trials outside the lab.
Finally, there’s the yuck factor. Sticking a small magnet on to the tongue may not be to everyone’s taste, though paralysed people may have other priorities, of course.
Yet there is an alternative. In 2009, a team of German and Japanese engineers was looking for a hands-free control system doctors could use during complex surgery. They came up with a pad of conductive cloth that sticks to the outside of the cheek and is activated by the tip of the tongue. Just as you move a mouse on its mat, the “mouth pad” detects the pressure of the tongue moving along inside the cheek. No magnet required.
Surgeons aren’t the only ones to benefit. Drivers answering calls on the road, or chefs checking recipe apps while cooking might prefer this hands-free approach. The pad could be installed in helmets or balaclavas and used by cyclists, motor cyclists and skiers, says Kai Kunze, one of the team at Osaka Prefecture University in Japan. Why risk frostbite to use a smartphone on the slopes when you could use your cheek to switch on an app or answer a call? “It looks dorky,” Kunze says, “but it works.”
Besides, some people don’t mind dorky. Take gamers. In 2011, Sony engineers filed a patent for a tongue-controlled gaming system. According to Sony, gamers would wear a mouthpiece that . The company won’t say whether it plans to commercialise the system, but given the lengths some gamers go to for the tiniest advantage, they might welcome the extra control a cheek pad offers. Besides, in a world where Google Glass wearers navigate the web with twitches and nods, perhaps a cheek pad or mouthpiece won’t look so odd. Go on, stick your tongue in your cheek. Now drop your mouse and joystick in the trash. After all, you’ve got them both licked.
Taste the world
Could your tongue enhance your interactions with the world? Gershon Dublon at MIT’s Media Lab in Cambridge, Massachusetts, has devised Tongueduino: an electrode-covered strip that hangs off the tongue and outside the mouth, absorbing data from the surroundings through an array of sensors and translating it into electrical signals that travel from tongue to brain. Tonguedino can report on electromagnetic fields, visual data and other information to create a constant flow of spatial information, encoded as tiny electrical pulses. For Dublon, it helps you understand your surroundings, yet isn’t as distracting as a smartphone. “It allows us to be more present where we are,” he says.
See the Tongueduino and more in our gallery: “Robot carers and exoskeletons: Latest disability tech“
This article appeared in print under the headline “Hand to mouth”
