BACKGROUND For a long time, DC conductance has been the most important parameter in electrodermal routine measurements. However, DC current flow polarizes the electrodes, electrolyzes the skin, disturbs the measurement of conductance by possible varying electromotive forces (EMFs) in the circuit, and impedes the registration of the skin endosomatic DC potential. METHODS We therefore present a measuring system where DC current was replaced by a small AC current in a monopolar system, enabling the DC potential and AC conductance to be measured simultaneously at the same skin site. RESULTS We have also found examples of skin potential (SP) response waveforms with diphasic sharp edges not appearing in the conductance waveforms. The potential responses were found to be more robust with respect to movement artifacts, and the instrumentation could discern whether the indifferent electrode actually was on an inactive skin site. CONCLUSION In order to study the generating mechanisms of EDA in detail, the SP must be measured without DC current flow and compared with AC conductance results.
Electrodermal activity by DC potential and AC conductance measured simultaneously at the same skin site.