The Tongue Drive System being developed at the Georgia
Institute of Technology (gatech.edu) lets incapacitated people, those with high-level spinal chord injuries, operate a computer or maneuver an electric wheelchair, all by moving their tongues. The device consists of upper and lower dental “retainers” a person wears and an Apple iPod or iPhone.
The retainers contain sensors for detecting magnetic fields. When the retainers are in place in the person’s mouth, the magnets are positioned at the four corners of the mouth. The top one includes a rechargeable lithium-ion battery and a transmitting antenna, while the lower retainer includes a charging coil and a microchip that provides the computing power for the sensors and a transmitter. Circuitry is mounted in an insulating, water-resistant material and all components are vacuum molded inside a standard dental acrylic. The retainers are custom made for each user, so they are a tight fit and do let the sensors shift position. There’s also a stud inserted in the person’s mouth, and the ball on the end of the stud contains a small magnet.
When the person moves his tongue, the sensors detect its position, which gets wirelessly transmitted by the battery-powered transmitter chip to the iPhone or iPod. Software on the Apple device determines where the user’s tongue is. This data then controls a computer cursor’s movements or acts as an electrical wheelchair’s joystick controller. Certain movements can also be interpreted as right or left mouse clicks.
To make the device more seamless for those in wheelchairs, Georgia Tech researchers have also built an interface that holds an iPod, receives data from the retainer transmitter, and sends it to the iPod, and also connects the iPod to a wheelchair and charges the iPod. There’s even a place to put the dental retainers at night to recharge them.
Users can add additional commands, combining two or more tongue movements that get interpreted as a specific command. The device can handle as many as the user can remember. This makes the device more useful and flexible than conventional sip-n-puff devices paralyzed people rely on to control computers and wheelchairs