Aug 28: NeuroSyn is built on a biodegradable PLLA-PTMC substrate with directionally aligned PCL fibers to guide axonal regeneration, and Au film electrodes are deposited to provide low impedance for long-term stable recording. NeuroSyn exhibits robust electrical stability, with the impedance remaining stable over 68 days, ensuring a high signal-to-noise ratio for chronic recordings. Accelerated degradation studies further reveal progressive polymer hydrolysis and eventual fragmentation, leaving only trace Au residues that can be cleared by macrophages in vivo without the need for surgical removal.
To evaluate NeuroSyn’s ability to monitor nerve recovery and decode motor intentions invivo, it is implanted in a rat sciatic nerve defect model, where it records neural signals during treadmill walking at 4 and 8 weeks post-implantation. Neural signal amplitude at 8 weeks post-implantation is substantially greater than that at 4 weeks, with SNR increasing from 9.5 dB to 19.5 dB. Spectral analysis time-locked to step initiation reveals that neural firing is tightly synchronized with swing events, with stronger signal intensity at 8 weeks post-implantation than that at 4 weeks. These results demonstrate that NeuroSyn enables real-time, multi-parametric tracking of nerve recovery, complementing traditional intermittent assessments by capturing continuous recovery dynamics.
Beyond real-time monitoring, the device decodes motor intentions from peripheral signals using a neural network model, achieving an overall classification accuracy of 95% with an area under the ROC curve of 0.991. Notably, when compared with M1 recordings in the same animals, peripheral nerve signals exhibit significantly higher power and swing index relative to step initiation, indicating superior synchronization with swing events. This advantage suggests that NeuroSyn-recorded peripheral signals, combined with machine learning, could offer more reliable motor control commands for exoskeleton-based rehabilitation than cortex-based approaches.
The system further supports bidirectional communication. NeuroSyn captures both descending signals from the spinal cord and ascending signals from peripheral effectors, while also delivering electrical stimulation to elicit muscle responses, confirming stable functional reinnervation throughout the regenerative process. This capability positions NeuroSyn as a potential closed-loop interface for real-time recovery monitoring and on-demand electrical therapy.
Together, these findings establish NeuroSyn as a biosynchronized, multifunctional transient peripheral nerve interface that integrates high-fidelity neural recording, accurate motor intention decoding, and complete bioabsorption without secondary surgery. NeuroSyn offers a new materials and device strategy for diagnosing and rehabilitating peripheral nerve injuries, laying a critical foundation for advancing adaptive neurorehabilitation.