A DRY ELECTRODE FOR EEG RECORDING

This paper describes the design, fabrication and testing of a prototyp e dry surface electrode for EEG signal recording. The new dry electrod e has the advantages of no need for skin preparation or conductive pas te, potential for reduced sensitivity to motion artifacts and an enhan ced signal-to-noise ratio. The electrode's sensing element is a 3 mm s tainless steel disk which has a 2000 Angstrom A (200 nm) thick nitride coating deposited onto one side. The back side of the disk is attache d to an impedance converting amplifier. The prototype electrode was mo unted on a copper plate attached to the scalp by a Velcro strap.The pe rformance of this prototype dry electrode was compared to commercially available wet electrodes in 3 areas of electroencephalogram (EEG) rec ording: (1) spontaneous EEG, (2) sensory evoked potentials, and (3) co gnitive evoked potentials. In addition to the raw EEG, the power spect ra of the signals from both types of electrodes were also recorded. Th e results suggest that the dry electrode performs comparably to conven tional electrodes for all types of EEG signal analysis. This new elect rode may be useful for the production of high resolution surface maps of brain activity where a large number of electrodes or prolonged reco rding times are required.