On the design of multi-site microelectrodes for neuronal recordings

The current understanding of how the nervous system functions is based on numerous observations of the behavior of single neuronal units or a small ensemble of units correlated to some external stimulation or behavioral event. However, the processing power of the nervous system lies in its network and interconnections. Thus the key to understanding the nervous system is to make simultaneous observations of the activity of numerous cells from within a functioning brain. The objective of the EU funded project VSAMUEL is to develop such a system based on silicon microelectrode arrays for acquiring signals from nervous tissue in vivo. The system will utilize advanced micro-structuring based on SOI wafers to design and fabricate probes with up to 128 recording sites: microelectrodes placed on tiny fork shaped probes. Those probes and the location of their shafts and recording sites, the probe design for short, does not only have to obey the rules imposed on them by the utilized micro-machining techniques, but by anatomical requirements as well, as demanded by the neurobiological experiment. The whole project not only includes the development of easy-to-use connectors and suitable multi-channel signal amplifiers, but also a novel highquality, high-throughput data acquisition system (DAQ), based on commonly available PC-computers and signal processing boards in conjunction with novel signal processing software.