Time based measurement of the impedance of the skin-electrode interface for dry electrode ECG recording

This paper reports the measurement of the properties of dry or pasteless conductive electrodes to be used for long-term recording of the human electrocardiogram (ECG). Knowledge of these properties is essential for the correct design of the input stage of associated recording amplifiers. Measurements were made on three commercially available conductive carbon based electrodes at pressures of 5mmHg and 20mmHg, located on the lower abdomen of the body on three subjects having different skin types. Parameter values were fitted to a two-time-constant based model of the electrode using data measured over a period of 10s. Values of resistance, ranging from 40k Omega to 1590k Omega and of capacitance ranging from 0.05 mu F to 38 mu F were obtained for the components, while the values of the time-constants varied from 0.07s to 3.9s.