An electrode includes a core of beryllium copper alloy and a safe metal coating. In some embodiments, the beryllium copper alloy comprises more than three percent beryllium, less than three percent other metals and a remaining percent copper. In some embodiments, an apparatus includes a headband, and a first and second safe metal coated copper-beryllium alloy electrode. The headband is configured to fit snugly to a head of a subject in an orientation from behind a first ear, across a crown of the subject, to a position behind a second ear. The first electrode and second electrode are disposed in the headband to contact a head of the subject at a first position and a different second position, respectively, without gels. In various embodiments, the headband includes a chip to determine an analog signal and transmit data； and, a system includes the headband and a signal analyzing unit.
