High-aspect-ratio neural electrode array fabrication using thermomigration process

Abstract

A novel fabrication process for a high-aspect-ratio recording and stimulation intracortical neural microelectrode array is described. Using a combination of dicing and KOH wet-etching, microspikes are formed on the surface of a n-type (100), 4 mm thick, silicon wafer. Deep 3 mm cuts are performed in order to produce sharped tip pillars of high-aspect-ratio (0.2x0.2x3 mm). Thermomigration is employed as a selective doping technique performing electrically insulated pillars due to the pn back biased junctions formed between each pair of n-type substrate and p+ migrated trails. Gold is deposited over the spikes in order to have a good ionic interface with the neural tissue, while the remaining surface is passivated with a biocompatible layer of cyanoacrylate. The final result is a deep penetrating electrode array with potential new applications in neuroprosthetics’ research field.