  Peripheral nerve injuries are difficult to treat due to limited axon
regeneration; brief electrical stimulation of injured nerves is an emerging
therapy that can relieve pain and enhance regeneration. We report an original
wireless stimulator based on a metal loop (diameter ~1 mm) that is powered by a
transcranial magnetic stimulator (TMS). The loop can be integrated in a
chitosan scaffold that functions as a graft when applied onto transected nerves
(graft-antenna). The graft-antenna was bonded to rat sciatic nerves by a laser
without sutures; it did not migrate after implantation and was able to trigger
steady compound muscle action potentials for 12 weeks (CMAP ~1.3 mV). Eight
weeks post-operatively, axon regeneration was facilitated in transected nerves
that were repaired with the graft-antenna and stimulated by the TMS for 1
hour/week. The graft-antenna is an innovative and minimally-invasive device
that functions concurrently as a wireless stimulator and adhesive scaffold for
nerve repair.
