ABSTRACT
This chapter reviews the origins, principles, and designs of instrumentation used in biopotential measurements, in particular for the electrocardiogram, the electroencephalogram, the electromyogram, and the electrooculogram. Many organs in the human body, such as the heart, brain, muscles, and eyes, manifest their function through electric activity. The origins of these biopotentials can be traced to the electric activity at the cellular level. Electrocardiogram signals are acquired by placing electrodes directly on the torso, arms, and legs. Electroencephalogram (EEG) signals are characterized by their extremely small amplitudes (in the microvolt range). EEG signals are difficult to interpret since they represent the comprehensive activity of billions of neurons transmitted via the brain tissues, fluids, and scalp. Electric potentials are generated as a result of movement of the eyeballs within the conductive environment of the skull. Electrodes for bio-potential recordings are designed to obtain the signal of interest selectively while reducing the potential to pick up artifact.
