For those unfortunate enough to suffer from severe spinal cord injuries, the tongue is often the only extremity still under their control. To take advantage of this fact, engineers at the Georgia Institute of Technology (GIT) have developed what they call the Tongue Drive System (TDS), a wireless, wearable device that allows the user to operate computers and control electric wheelchairs with movements of the tongue. The latest iteration, which resembles a sensor-studded dental retainer, is controlled by a tongue-mounted magnet and promises its users a welcome new level of autonomy with both communication and transportation.

Previous versions of the TDS featured an externally-worn headset that tracked movements of the tongue-mounted magnet. Unfortunately, any shift of the headset meant the whole system had to be recalibrated. Maysam Ghovanloo, an associate professor of electrical and computer engineering at GIT explains how they leaped that hurdle - "By moving the sensors inside the mouth, we have created a Tongue Drive System with increased mechanical stability and comfort that is nearly unnoticeable."

"Because the dental appliance is worn inside the mouth and molded from dental impressions to fit tightly around an individual's teeth with clasps, it is protected from these types of disturbances," Ghovanloo added.

The new TDS configuration sports magnetic field sensors on each of its four corners which detect movements in the tongue-mounted magnet. Output from the sensors is then wirelessly beamed to special app-equipped iPods or iPhones which decipher the user's intended commands in real-time by ascertaining the tongue magnet's position relative to the other sensors. That data can then drive a computer's cursor or double for the joystick control of an electric wheelchair. A tiny rechargeable lithium-ion cell powers the entire unit, which is covered with water-resistant insulation and vacuum molded into a custom-made dental-acrylic appliance.

The TDS iPhone/wheelchair interface

Over the past several months, the GIT team recruited several initial test subjects with appreciable spinal cord damage to try out the headset TDS configuration. Presumably, the biggest hurdle for the participants was the mandatory clinical tongue piercing each received to affix the magnet-topped stud, but in spite of the need for occasional unit calibration, the concept proved sound.

"During the trials, users have been able to learn to use the system, move the computer cursor quicker and with more accuracy, and maneuver through the obstacle course faster and with fewer collisions," said Ghovanloo. "We expect even better results in the future when trial participants begin to use the intraoral Tongue Drive System on a daily basis."

Source: Georgia Institute of Technology