A comprehensive model for power-line interference in biopotential measurements

Power-line interference is a major problem in high-resolution biopotential measurements. Because interference coupling is mostly capacitive, shielding electrode leads and a high common-mode rejection ratio are quite effective in reducing power-line interference but do not completely eliminate it. We propose a model that includes both interference external to the measuring system and interference coming from its internal power supply. Moreover, the model considers interference directly coupled to the measuring electrodes, because, as opposite to connecting leads, electrodes are not usually shielded. Model analysis reveals the most significant parameters and experimental results confirm that reducing interference coupled through the additional coupling channels considered yields a negligible interference