Implantable multichannel electrode array based on SOI technology

This work presents a new method of fabricating implantable multielectrode arrays on lightly doped single-crystal silicon. Such arrays are essential tools for electrical stimulation and recording of nerve signals. Our new microfabrication process, based on silicon-on-insulator (SOI) technology, inherently has excellent control over the final probe thickness without wet etching. The needle shanks are 6 mm long and 80 mum wide. Here the thickness of the probe, 25 mum, is defined by the device layer thickness on the SOI wafer. Our new sprinkler fluidic channel, which has holes spaced 50 mum apart along its 6 mm length, permits the perfusion of a large area of tissue with any desired neurotransmitter or other drug. The probes fabricated here are tested in the cat primary visual cortex; data recorded from adjacent neurons was used to characterize their orientation tuning. The sprinkler channel was characterized, and flowrate through the channel is a linear function of the applied pressure.