Design and construction of a multiplexed electrode for monitoring evoked responses in cerebral cortex

On October 25, 1982, an X-Y addressable, 16- electrode, 4-by-4 Array, multiplexed switching electrode chip was implanted on the brain of a laboratory beagle. The purpose was to monitor the electroencephalogram (EEG) and visually evoked response (VER) data. This paper proposes a second-generation brain chip with design improvements incorporated, describes the fabrication techniques used to design a chip capable of monitoring visually evoked brain signals, and discusses the theory of operation associated with the chip. The second-generation brain chip includes self-contained power with on-board multiplexing and clocking circuits. The most significant improvement is the incorporation of analog-to-digital (A/D) converters. By using A/D converters, brain signal data can be converted at the site of implant, eliminating induced noise from analog wires used on the original chip.