Highly doped silicon microtubular electrodes for neural recording

The use of highly doped n++ silicon areas as recording microelectrodes is discussed. While electrode impedance measured for planar (<100>) electrodes is worse than the one obtained for conventional metal electrodes (Pt, Ir), the value reduces one order of magnitude if vertical electrodes are used. Even lower values than for Pt electrodes are reached in this last case. The vertical orientation of the highly doped Si electrode, its complete compatibility with CMOS processes, and its proved biocompatibility make it a reasonable good choice in the fabrication of regenerative-type neural interfaces and, in general, in those applications requiring on-chip microelectrodes and integrated circuitry.