Simultaneous selective stimulation and impedance measurement of the human skin

An electronic device for electrical stimulation and measurement of the skin impedance is described. The device allows to program any type of waveform for stimulating the skin. Two investigative experiments were performed to assess the effects of different electrical pulse shapes in the pain sensation and in the measured electrical impedance values. The selective fibers stimulation was studied with two waveforms: quasi-trapezoidal and regular square pulse. Both waveforms had the same energy. Tests were performed by analyzing the pain intensity and skin impedance variation for these signals. The results showed that the pain intensity during the stimulation could be minimized using the proposed quasi-trapezoidal pulse. Moreover a slight difference in the skin impedance was also observed. The proposed device can be used as a tool for testing arbitrary signals in order to find out the best pattern for the selective stimulation of the human skin.