Novel Bioelectrical Measurement using a Digital Biopotential Monode

In conventional biopotential recording, two or more electrodes are placed on the body. A unipolar lead records the time-varying electrical potential at a single point (relative to a reference potential) via one signal electrode. A bipolar lead records the time-varying potential difference between two points via two signal electrodes. In each case, the signal electrodes are connected to high impedance amplifier inputs, while an additional electrode provides a low-impedance path between the amplifier and human subject. Bipolar leads are usually preferred since interference appearing at both signal electrodes can be eliminated using an instrumentation amplifier with high CMRR. A drawback of bipolar lead recording is that wires must connect all electrodes to the amplifier. This paper presents preliminary work on a novel design for a digital biopotential measurement device which we call the biopotential monode.