Capacitive Type of Biomedical Electrode

A suitable dielectric for a capacitive biomedical electrode is presented. In application a thin (2-mil) film of pyre varnish is deposited on the electrode surface and heat cured. Capacitance values of 800 pF for a 0.5-inch-diameter electrode are typical. A field-effect transistor source follower circuit is used in conjunction with this type of electrode.