Peripheral nerve regeneration through microelectrode arrays based on silicon technology

This paper describes some developments, made to obtain a chronic neural interface to record signals from regenerated peripheral nerves. Microperforated silicon dices, fabricated by techniques compatible with CMOS processes, were coupled in silicone nerve chambers and implanted between the severed ends of peripheral nerves in rats. Three configurations of perforated dices with 25 via-holes of 100 μm diameter, 121 via-holes of 40 μm and 400 via-holes of 10 μm were assessed. The feasibility of axonal regeneration through the dices via-holes was proved by histological and physiological methods over 3 months post-implantation. The regenerated nerves were organized in fascicles corresponding to the grid pattern of the via-holes. However, nerve regeneration was difficult and distal re-innervation delayed with respect to simple tubulization repair. The size of the via-holes and the total open area are determinants of the degree and quality of regeneration. Further improvements are needed in both the microelectrode dice design and in neurobiological stimulation of regeneration.