Robust and real-time monitoring of nerve regeneration using implantable flexible microelectrode array

This paper presents a robust and quasi-real-time monitoring method for examining the degree of regeneration of peripheral nerves using a polymer-based implantable microelectrode array (IMA). The IMA was implanted in the sciatic nerves of rats using two different approaches: (1) direct implantation which was achieved by directly suturing to nerve stumps for short-term regeneration and (2) assembly implantation which was achieved by implanting the IMA assembled with a resorbable conduit that cross a 4-mm nerve defect. The regeneration of the injury was evaluated by measuring the nerve signals following foot pricking and impulse stimulating to the proximal stump. The direct implantation produced a peak voltage of 3.43 mV before amplification and a conduction velocity of 19.8 m/s. The assembly implantation produced a peak voltage of 1.51 mV and a conduction velocity of 18 m/s. The degree of regeneration was also examined using gait and morphological analyses. The sciatic function index was -38.5 ± 12.5 for direct implantation and -64.9 ± 7.5 for assembly implantation. The morphologies of the regenerated nerves were examined using toluidine blue, transmission electron microscopy images, and pilot tests. Te regeneration ratios after the direct and assembly implantation were 45% and 21%, respectively.