Introduction and preliminary evaluation of the Tongue Drive System: wireless tongue-operated assistive technology for people with little or no upper-limb function.

We have developed a wireless, noncontact, unobtrusive, tongue-operated assistive technology called the Tongue Drive System (TDS). The TDS provides people with minimal or no movement ability in their upper limbs with an efficacious tool for computer access and environmental control. A small permanent magnet secured on the tongue by implantation, piercing, or tissue adhesives is used as a tracer, the movement of which is detected by an array of magnetic field sensors mounted on a headset outside the mouth or on an orthodontic brace inside. The sensor output signals are wirelessly transmitted to an ultraportable computer carried on the user's clothing or wheelchair and are processed to extract the user's commands. The user can then use these commands to access a desktop computer, control a power wheelchair, or interact with his or her environment. To conduct human experiments, we developed on a face shield a prototype TDS with six direct commands and tested it on six nondisabled male subjects. Laboratory-based experimental results show that the TDS response time for >90% correctly completed commands is about 1 s, yielding an information transfer rate of approximately 120 bits/min.