A wireless and fully-implantable optogenetic stimulation system for long-term monitoring of upper limb functions with sub-nerve resolution

Motor function defect caused by central or peripheral nerve injuries has become a global burden. Peripheral nerve transfer is an effective surgical method in restoring motor functions of upper limb after nerve injuries in general. However, the outcome of individual function recovery is less predictable. It is crucial to access the real-time monitoring of function improvement in the peripheral nerve level. Here, we developed a fully implantable multisite optogenetic stimulation system(FIMOSS), which is tailored for wireless, reprogrammable and long-term monitoring of peripheral nerve plexus functions. In Thy1-ChR2-EYFP mice, our system elicited diverse forelimb movements when illuminating each nerve bundle from different angles, confirming its spatial selectivity for the monitoring of precise brachial plexus functions. Furthermore, we applied FIMOSS on a nerve transfer mice model after traumatic brain injury and discovered innervation pattern of the transferred nerve to multiple forelimb muscles along with the functional compensation of adjacent nerve trunks in brachial plexus consecutively within 12 weeks after surgery, during which FIMOSS has demonstrated stable operation. Our technology enabled refined evaluation of electrophysiological and motor functions of peripheral nerve plexus, shining light upon personalized diagnosis and treatment after central or peripheral nervous system injuries or nerve surgeries.