Maximal dynamic range electrotactile stimulation waveforms.
A new method to measure the dynamic range of electrotactile (electrocutaneous) stimulation uses both steepest ascent (gradient) and one-variable-at-a-time methods to determine the waveform variables that maximize the subjective magnitude (intensity) of the electrotactile percept at the maximal current without discomfort for balanced-biphasic pulse bursts presented at a 15-Hz rate. The magnitude at the maximal current without discomfort is maximized by the following waveform (range tested in parentheses): number of pulses/burst = 6 (1-20), pulse repetition rate within a burst = 350 Hz (200-1500), and phase width = 150 microseconds (40-350). The interphase interval (separation between positive and negative phases in a biphasic pulse) does not affect dynamic range from 0-500 microseconds. The number of pulses/burst has a large effect on the perceived dynamic range when this is measured using a subjective-magnitude-based algorithm, whereas it has little effect on the traditional dynamic range measure, i.e., (maximal current without discomfort)/(sensation threshold current). The perceived stimulus magnitude at the maximal current without discomfort is approximately twice as strong with 6 pulses/burst as it is with 1 pulse/burst (a frequently-used waveform).
Kaczmarek
K A
KA
Department of Electrical and Computer Engineering, University of Wisconsin, Madison 53706.
Webster
J G
JG
Radwin
R G
RG
D015982:Bias; D003198:Computer Simulation; D004558:Electric Stimulation; D005069:Evaluation Studies as Topic; D006801:Humans; D012016:Reference Values; D012684:Sensory Thresholds; D012879:Skin Physiological Phenomena; D014110:Touch / Q000502:physiology*