Insulated Active Electrodes

The need for reliable, easily applied, dry electrodes for use in medical applications has prompted investigation in many directions. Most wet or paste type electrodes are not only irritating to the skin when used over long periods of time, but also require careful skin preparation for clinically useful results. An insulated electrode technique has been reported which requires no skin preparation and is immune to artifacts induced by electrode polarization. This electrode consists of an anodized metal disc which relies upon capacitive coupling with the skin to derive its electrical signal. The signal output of the electrode is coupled directly into an FET source follower which has an output impedance of 5000 ohms, and is coupled into standard clinical recording equipment. This paper reports further improvements in the development of electrodes of this type.