Active microelectrode array to record from the mammalian central nervous systemin vitro

The detection of extracellular potentials in nervous tissue with conventional microelectrodes has many limitations. The number of sites at which activity can be detected in one experiment is small, and the noise performance of the system is frequently poor. A monolithic integrated circuit array of microelectrodes and buffer amplifiers has been built, enabling potentials to be detected simultaneously at nine sites, and substantially reducing the noise caused by electrostatic pick-up. The electrodes and buffer amplifiers were made on a silicon substrate using a fabrication process based on standard i.c. processing techniques. With an off-chip multiplexer, the potentials at each electrode have been displayed simultaneously on a normal oscilloscope in experiments on slices of rat brain tissue. Initial results have shown that an informative display which would be almost impossible to obtain with conventional electrodes can readily be produced, and that the long-term stability of the device is good.