Bidirectional interfaces with the peripheral nervous system.

Considerable scientific and technological efforts have been devoted to develop neuroprostheses and hybrid bionic systems that link the human nervous system with electronic or robotic prostheses, with the main aim of restoring motor and sensory functions in disabled patients. Such developments have also the potential to be applied to normal human beings to improve their physical capabilities for bidirectional control and feedback of machines. A number of neuroprostheses use interfaces with peripheral nerves or muscles for neuromuscular stimulation and signal recording. This chapter provides a general overview of the peripheral neural interfaces available and their use from research to clinical application in controlling artificial and robotic prostheses and in developing neuroprostheses. Extraneural electrodes, such as cuff and epineurial electrodes, provide simultaneous interface with many axons in the nerve, whereas intrafascicular, penetrating, and regenerative electrodes may selectively contact small groups of axons within a nerve fascicle. Biological and technical issues are reviewed relative to the problems of electrode design and tissue injury. The last sections review different strategies for the use of peripheral neural interfaces in biomedical applications.