Newly explored electrical properties of normal skin and special skin sites.

Skin impedance measurements at various skin sites yield different impedance loci for normal skin and special skin sites. The results of skin impedance measurements taken at such sites with a two-electrode measurement system are presented herein. Some of these sites can be identified as acupuncture points. Data from 4 volunteers were acquired by means of a data acquisition board and a measuring system consisting of the measurement circuit, including several electrode types, and a power supply. The Cole model is a model for an equivalent electrical circuit of the skin-electrode system. The system was used to derive skin-typical parameters from the Bode plot of the whole system. These parameters are the fractional power a, the pseudo-capacity K, the parallel resistance Rp, and the serial resistance Rs of the equivalent electrical circuit. The results show that the measured parameters differ between normal skin and special skin sites. These effects have not previously been discovered by other authors, since there has been no systematic investigation of many acupuncture points to date, and there has been no apparent need for such an investigation. A number of necessary criteria for acupuncture point detection can be derived from the results obtained.