Micromachined multi-channel microelectrodes with titanium nitride sites

Titanium nitride (TiN) has been shown to offer charge-delivery/impedance characteristics equivalent to or better than those of the activated iridium now used for microelectrodes. This paper further explores the performance of TiN sites fabricated by reactive sputtering in nitrogen/argon. Using lift-off, TiN sites have been formed on fully-processed multi-channel microprobes capable of recording and stimulation in the central nervous system. The sites have been found to be fully compatible with the probe process, with clean lift-off even when deposited using low grazing-angle sputtering. The TiN is attacked at less than 2 nm/min in the ethylenediamine pyrocatechol (EDP) release etch. Single-unit neural recordings have shown that TiN sites produce signal-to-noise ratios similar to those of iridium.