SQUARE-WAVE ANALYSIS OF SKIN IMPEDANCE

A method is described for studying skin impedance phenomena, based on analysis of waveforms of current through the skin produced by square voltage pulses. In several experiments, the method is used to provide data relevant to the choice of an appropriate equivalent circuit for skin. Removal of the stratum corneum eliminates the parallel resistive and capacitative elements, and slightly reduces the series or ‘ohmic’ resistance. During healing the source of skin potential recovers before the other electrodermal parameters have returned to normal. The relationship of these parameters to electrode area, current density, and site temperature is studied. It is argued that the capacitance of skin may not vary with the frequency of the measuring current, in contrast to traditional views. The main purpose of the paper is to illustrate and advocate the square-wave method of analysis.