Noise of surface bio-potential electrodes based on NASICON ceramic and Ag-AgCl

The electrochemical noise from dry NASICON-based surface electrodes and pregelled Ag-AgCl electrodes is evaluated in saline solutions and on the skin. The electrochemical noise from the electrode/electrolyte interface is found to be negligible (less than 1 mu V peak to peak), On the skin, the noise level is highly dependent on the patient. At high frequencies, the skin/electrode interface noise is equal to 'thermal noise' and can be related to the real part of the skin/electrode impedance. At low frequencies (f<100 Hz), excess noise is observed that varies as f(-2) It is tentatively ascribed to a non-stationary process or noise of electrochemical origin due to the ionic nature of the skin. The contribution of residual EMG signal of low amplitude (5 mu V peak to peak) is suggested for electrodes with large surface area.