P25. NEUROSTITCH: NANOFABRICATION OF A HIGH RESOLUTION, BIOMIMETIC PERIPHERAL NERVE INTERFACE

Abstract

PURPOSE: Over a million people suffer limb loss annually. Existing prostheses are cumbersome with a limited capacity to recapitulate natural hand motion. A stable, high-fidelity neural interface is necessary for 2-way communication between robotic prostheses and the patient’s neural circuitry. Existing neural interfaces are limited by the trade-off between invasiveness, resolution and longevity. METHODS: Ultra-small, flexible electrodes of the same dimensions and compliance as human axons were fabricated. A ‘needle and thread’ approach was used to implant the ultra-flexible devices. Using histology, 2-photon imaging, and the Sciatic Functional Index (SFI), we assessed the neural injury and foreign body reaction (FBR) associated with the device. The Intan system was used to stimulate and record. RESULTS: SFI demonstrates resolution of the initial neuropraxia to baseline by 2 weeks post-implantation. Action potentials were recorded within 30 minutes of device insertion. The size of the electrodes and proximity to individual axons permitted local stimulation — down to a single toe. Immunohistochemistry demonstrated an absence of FBR at 6 months. CONCLUSION: We have fabricated and inserted biomimetic intraneural electrodes with minimal and recoverable nerve injury and absence of FBR. The Neurostitch is capable high selectivity stimulation. This device represents a step forward in the development of a high-resolution, stable man/machine interface for next-generation neuroprostheses.