Micromachined silicon substrate electrodes for extracellular recording

This paper reviews the present status of multichannel silicon microprobes for recording extracellular potentials in CNS. A wide variety of probe geometries are now available for acute and chronic electrophysiological studies. One and two dimensional arrays offer possibilities for precisely placed electrode recording sites meeting the geometrical needs of the investigation by matching the cytoarchitecture of the tissue under study. Similar multichannel stimulating arrays allow precisely controlled current/charge waveforms to be delivered to highly-localized areas of tissue. On-chip circuitry has been developed for these probes to permit features such as amplification, impedance buffering, multiplexing, and self-testing to be realized, while minimizing the number of external leads. Long term chronic experiments are possible through the use of an unique silicon ribbon cable construction which integrates the interconnect with the electrode thus removing the need for failure prone bonds near the electrode.