Background
A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied withoutany skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has highelectrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectricsignal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, andcompared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode withan impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrodeand our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1)the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance ofthe developed electrode was lower than that of the Ag/AgCl electrode (0.3