The Impedance Property of Electrode Used in Electrical Bio-Impedance Measurement

The object of electrical bioimpedance measurement is the impedance or impedance changes of biologic tissue. The electrode used in electrical bioimpedance measurement works under AC stimulation, the electrode impedances of both DC and AC, the stability of them are much important. AC and DC impedance properties of four kinds of one-off Ag/AgCl ECG electrodes produced by different manufactories, and the variability of them have been studied in this paper. It turns out that the AC and DC impedance and the variability of different kinds of electrode are different significantly. After stimulated for a long time by AC current, the electrode resistance value between positive direction and negative direction have a notable difference. It suggests that the DC resistance character of the measured electrode changes greatly when the electrode used in impedance measurement.