Reduction of power line interference using active electrodes and a driven-right-leg circuit in electroencephalographic recording with a minimum number of electrodes

Unwanted power line interference is one of the most common problems in electroencephalographic recording. This paper examines how the use of active electrodes together with a driven-right-leg circuit can significantly improve interference reduction, even when the same electrode is used for common and reference which is attractive because it saves an electrode. General conclusions about the active electrodes and the driven-right-leg circuits were obtained thanks to a prototype that uses the same electrode for both common and reference. Measurements were performed both on a subject and on an electrical equivalent model.