Advances in Thin-Film Graphene Neurotechnology for Chronic Nerve Stimulation and Recording

Abstract

Neurotechnology is being explored for restoring sensorimotor functions after paralysis or amputation, which requires peripheral nerve interfaces that are selective, bidirectional, and chronically stable. Reduced graphene oxide (rGO)-based microelectrodes offer low impedance and a high charge-injection limit; however, long-term in vivo performance has been limited by the durability of encapsulation. Here, we introduce a 10 {micro}m-thick transverse intrafascicular multichannel electrode (TIME) with a hybrid polyimide-Al2O3 encapsulation engineered to improve fabrication yield, electrode-to-electrode uniformity, and device stability. In vitro, devices maintained near-ideal capacitive behaviour after accelerated ageing (3 months in PBS at 57 {degrees}C) and sustained 109 biphasic stimulation pulses without detectable electrochemical degradation. In vivo, the arrays recorded compound nerve action potentials after one month and enabled selective activation of distinct peripheral nerve fibres with comparatively low current thresholds during four months of follow-up, remaining below the device maximum injectable current. Together, these results demonstrate that combining graphene microelectrodes with a thin hybrid encapsulation improves chronic reliability of intraneural thin-film interfaces and helps to close the gap between laboratory prototypes and clinically relevant neuroprosthetic systems.