Characteristics of skin impedance for biological active points using dry electrode measurement system

Acupuncture points may show special electrical properties. Various investigations have been taken to locate these points by using skin impedance measurements. The biological active points (BAPs) or acupuncture points are known to have lower electric impedance than the surrounding skins. The conventional wet electrode measuring method is difficult to do fast because of long application and stabilization times. Dry BAPs measure electrode (DBME) is proposed to distinguish between BAP and non-BAPs for better precision. DBME can remove gel-related noise, as well as maintaining a good contact impedance to minimize interference noise. The manufactured DBME system can measure specific BAPs impedance automatically with constant pressure. Measurements were taken at BAPs: PC6 and PC5 are both on the left forearm and ST36 is on the left leg. The total pressure applied to the electrode was adjusted to be 500 (gf) by a pressure gauge instrument. Resistances of BAPs of BAPs1 (PC6), BAP2 (PC5) and BAPs;3 (ST36) are about 25 I Omega, 15 I Omega and 15 I Omega less than those of non-BAPs. In this paper, the impedance of BAPs are much lower than that of the surrounding skins. We have found there is a linear relationship between the skin impedance and the contact pressure. We plan to search and identify the exact location of BAPs with a dry electrode BAPs measuring system.