Electrical stimulation of skin for information transmission--III: sequential signal transmission.

: The transmission of sequentially discrete coding signals such as Morse Code from machines to human beings by means of skin sensation was tested by electrical stimulation of skin. Here, the temporal response of skin sensation to electrical stimulation of skin is a very important factor. In this study, the temporal characteristics of skin sensation when transmitting sequential signals were examined and two modulation methods of electrical stimulation of skin were evaluated. One uses a coaxial electrode with temporal modulation and the other uses a coaxial electrode array with spatio-temporal modulation. It has been found that temporally sequential signals are recognized with higher accuracy with spatio-temporal modulation than with temporal modulation. Information transmission performance was also quantitatively analyzed using the Information Theory.