A Feasibility Study to Elicit Tactile Sensations by Electrical Stimulation

In this paper we investigated the feasibility of electrically-elicited tactile sensations. Eighteen subjects participated in the experiment and the constant current stimulation was applied to the subject’s index finger pad. The cathodic monophasic rectangular pulse train was used throughout the experiment. The pulse amplitude was increased in every 2.5 seconds in such a way that the charge increment per pulse was kept constant at 70 nanoC. Four different pulse widths (200, 500, 700 and 1,000 us) and three different frequencies (20, 50 and 200 Hz) were selected to investigate the effect of the pulse parameters on the elicited tactile sensations.

The tickling sensation was elicited in all the subjects. Pressure, low and high frequency vibration were successfully evoked in 17, 13 and 12 out of 18 subjects. The activation threshold and the pain threshold (in mA) were low for large pulse widths. For each pulse width, each of the four sensations was perceived in almost the same number of subjects. We found that the sensation frequency was in accordance with the stimulation frequency; LH vibration and HF vibration were seen dominantly at low frequencies and high frequencies, respectively. The experimental results suggested that it is possible to elicit a group of tactile sensations by applying electrical stimulation to the skin.