Technology and fabrication of hybrid neural interfaces for the peripheral nervous system

New generations of limb prostheses incorporating internal and external sensors, and sophisticated systems for functional electrical stimulation (F.E.S.) could be used widely if neural interfaces capable of connecting intimately the nervous system "inside" the human being and the external world were available. Microsystems technology provides tools to develop such neural interfaces, although a number of challenging problems must be solved, which are related not only to technology, but mostly to the difficulty of tightly coupling delicate living tissues and artificial microstructures. This paper describes the approach followed by an interdisciplinary team of researchers within the framework of the ESPRIT Project "INTER", and some results which have been obtained so far. Details are given on the fabrication of silicon dices with miniature via-holes through which axons regenerate, and on the fabrication of polymer channels which guide and promote nerve regeneration. The silicon dices are then incorporated into the guidance channels, thus forming hybrid microsystems which might open intriguing new applications for research and healthcare.