A computer-controlled system for measuring an impedance locus of palmar skin

Compared to direct current (DC) methods, alternating current (AC) methods have rarely been used in the field of electrodermal research. AC methods, however, have the advantage of enabling analysis of electrodermal activity, including capacitive properties. To establish an easy AC method, a computer-controlled measurement system was developed in this study. The system can automatically measure impedances at three different frequencies on the basis of phase detection and determine an impedance locus. Performance tests using RC parallel circuits showed that the system has sufficient accuracy. Palmar skin impedance was also measured and temporal changes in parameters of the circular arc law were investigated. It was demonstrated that the system can obtain impedance data with a data acquisition time of less than 0.2 s and can easily determine an impedance locus. It is expected that the new system, due to its high level of accuracy and ease of operation, will be used as an AC method of measuring electrodermal activity.