Intraneural microstimulation for enhanced prosthetic control using a peripheral nerve interface

The functionality of prosthetic arms would be enhanced by incorporating cognitive feedback about tactile events, grasp force and hand position. This goal may best be met by interfacing directly with the peripheral nerves in the prosthesis user's residual limb. We are presently exploring a variety of interface designs based on arrays of fine wires. The efficacy of nerve fiber activation and the biocompatibility of the arrays are being studied by chronic implantation into the transected tibial nerve in the rabbit. A behavioral eye blink conditioning paradigm was implemented to assess the implant functionality over time. Our ultimate goal is to achieve stable activation of single tactile afferents. Results show that stable nerve activation with thresholds on the order of 2 nC/stimulus phase (100 /spl mu/s stimulus), can be achieved for a long period (at least 15 months has been verified in one animal that is still being observed). Using the eye blink test paradigm, it is not possible to verify if the behavioral threshold represents single fiber activation. However, in view of the low stimulus threshold, it is likely that only a few fibers are being activated.