This work was supported by The University of Wisonsin–Madison Robert Draper Technology Innovation Fund, The University of Wisconsin–Madison Industrial & Economic Development Fund, and the Charles E. Culpeper Foundation (Partnership for Cures). The project was conducted in 1998 at the University of Wisconsin–Madison, and the principal investigator was Paul Bach-y-Rita.
In this project we demonstrated, we believe for the first time, that humans are capable of perceiving geometric shapes on their tongues. We used the 7x7, or 49-electrode array originally developed for fingertip electrotactile stimulation.
Five sighted adult human subjects (3M/2F) each received 4 blocks of twelve tactile patterns, approximations of circles, squares, and vertex-up equilateral triangles, sized to 4x4, 5x5, 6x6, and 7x7 electrode arrays. Perception with electrical stimulation of the tongue is better than with fingertip electrotactile stimulation, and the tongue requires 3% (5-15 V) of the voltage. The mean current for tongue subjects was 1.612 mA. Tongue shape recognition performance across all sizes was 79.8%. The approximate dimensions of the electrotactile array and the dimensions of compartments built into dental retainers have been determined. The goal is to develop a practical, cosmetically acceptable, wireless system for blind persons, with a miniature TV camera, microelectronics and FM transmitter built into a pair of glasses, and the electrotactile array in a dental orthodontic retainer. This work is published.
Form perception with a 49-point electrotactile stimulus array on the tongue: A technical note, J. Rehab. Res. Dev., vol. 35, pp. 427-430, 1998.