Preliminary experiments in nerve regeneration through laser-drilled holes in silicon chips

Abstract

Many of the present limitations of peripheral nerve repair might be overcome by performing nerve repairs at the axon level. One approach to nerve repair at this level would be to implant a neuroprosthesis in the form of a microelectronic switchboard which could route the connections of regenerated axons to their correct destinations. This requires a merger of microsurgery and microelectronics. Three steps are needed to achieve this goal. (1) The achievement of in vivo compatibility and electrical contact between axons and a material compatible with microelectronics. (2) The fabrication of a microelectronic neuroprosthesis with electrodes to establish communication with the axon. (3) The development of signal processing hardware and software to control the mapping of the regenerated axons. This report describes preliminary experiments in regenerating peripheral nerve axons through an electronic-grade silicon chip with laser-drilled holes small enough to capture either one or a few axons per hole. We have observed the viability of such nerves in 4 rats for 6 months to 1 year, and in two primates for more than 3 months. As our experiments show, this technique is not yet as effective as suture repair, but the development of a neuroprosthesis that communicates with peripheral nerve axons could have applications including nerve repair, neuroma, and nerve grafts, as well as interfacing the peripheral nervous system to prostheses of other kinds.