Dry skin offers high impedance to the flow of an electrical current (18). Stripping the skin by successively removing layers of the stratum corneum with an adhesive tape reduces the electrical resistance about sixfold, which tells us that the horny layer is the skin's prime electrical insulator. Its high impedance complicates the measurement of body potentials, as is done in electroencephalograms and electrocardiograms. Consequently, electrodes having large contact areas are used to monitor the brain's and the heart's electrical rhythms. Granular salt suspensions or creams and pastes containing high percentages of electrolytes are placed between the electrode surface and the skin to assure that the electrical conductance is adequate to make the measurements.
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