Comparison between the AC and DC measurement of electrodermal activity

Abstract

Recording electrodermal activity is a well-accepted physiological measurement for clinical approaches and research. Historically, applying a DC (direct current) signal to the skin to measure the conductance is the most common practice for exogenous recordings. However, this method can be subject to error due to electrode polarization even with "nonpolarizing" electrodes-a problem that can be eliminated with alternating current (AC) methodology. For that reason, Boucsein et al. () called for research demonstrating an AC method that is validated by comparison to standard DC methodology. Additionally, the complex structure of human skin has electrical properties that include both resistance and capacitance, and AC recording enables the measurement of skin susceptance (associated with current flow through capacitors). Finally, AC recording permits the simultaneous recording of the endogenous skin potential. In this paper, the results from a direct comparison between both methods are presented, which has not been reported previously. The results demonstrated excellent agreement between a 20 Hz AC method and a standard DC method, supporting the validity of the AC recording methodology employed. The results also showed that an applied voltage of 0.2 V is sufficient for DC recordings.

Innovations in Electrodermal Activity Data Collection and Signal Processing: A Systematic Review

“…The method overestimated the skin conductance by about 20%, suggesting that the proposed skin admittance method is not suitable for the estimation of a low-frequency skin conductance level, but the method can still be used to collect the variations of EDA at higher sampling rates. A more recent study aimed toward directly comparing AC and DC measurements of EDA, following the suggestion from Boucsein et al [3], in order to validate the AC method by comparing it to a standard DC method [27]. They found a voltage of 0.2 V to be sufficient for DC recordings.…”

Gender Differences in Tonic and Phasic Electrodermal Activity Components

“…Then digitized signals were processed by differentiation in the PC LabVIEW, and separated into a DC component for SP and an AC component for SC from the real part of the SY signal and SS from the imaginary part by means of phasesensitive rectification. The reason for choosing signal frequency (20 Hz) in this study was because a frequency of 20 Hz provides a good trade-off between measurement speed and sensitivity for sweat duct activity (Pabst et al, 2017).…”

“…The employed electrodes were Kendall Kittycat 1050NPSM Ag/AgCl solid gel ECG neonatal electrodes with an active area of 5.05 cm 2 ( Pabst et al, 2017). This type of electrode is selected since it is found to be suitable for EDA recordings.…”

Electrodermal activity patient simulator

“…They are predominantly used because of their simplicity, the need for only two electrodes, and possibility of monitoring both tonic and phasic EDA signals. They do, however, lack some advantages of endosomatic method (which is a very unobtrusive method with no special amplifying and coupling systems needed) and AC exosomatic method (no electrode polarization issues) [1,36]. There is a huge variety of EDA devices available (portable, battery powered, embedded or built-in in other settings (e.g.…”