A wireless tongue-computer interface using stereo differential magnetic field measurement.

We have developed an enhanced prototype of the new Tongue Drive system (TDS), which is a noninvasive, unobtrusive wireless magnetic tongue-computer interface for people with severe disabilities. A small permanent magnet secured on the tongue using tissue adhesives, implantation, or piercing is utilized as a tracer to track tongue movements. The magnetic field variations due to the tracer movements are detected by a pair of 3-axial linear magnetic sensor modules mounted bilaterally on a headset near the user's cheeks. The sensors stereo outputs are processed and translated into user control commands after being wirelessly transmitted to a portable computer. These commands have been used in human trials to access the computer by substituting mouse functions. Measurement results showed a response time of less than 1.0 s with 99.9% accuracy for 6 direct commands, yielding an information transfer rate (ITR) of 150 bits/min.