In Vivo Cellular‐Level 3D Imaging of Peripheral Nerves Using a Dual‐Focusing Technique for Intra‐Neural Interface Implantation

In vivo volumetric imaging of the microstructural changes of peripheral nerves with an inserted electrode could be key for solving the chronic implantation failure of an intra‐neural interface necessary to provide amputated patients with natural motion and sensation. Thus far, no imaging devices can provide a cellular‐level three‐dimensional (3D) structural images of a peripheral nerve in vivo. In this study, an optical coherence tomography‐based peripheral nerve imaging platform that employs a newly proposed depth of focus extension technique is reported. A point spread function with the finest transverse resolution of 1.27 µm enables the cellular‐level volumetric visualization of the metal wire and microstructural changes in a rat sciatic nerve with the metal wire inserted in vivo. Further, the feasibility of applying the imaging platform to large animals for a preclinical study is confirmed through in vivo rabbit sciatic nerve imaging. It is expected that new possibilities for the successful chronic implantation of an intra‐neural interface will open up by providing the 3D microstructural changes of nerves around the inserted electrode.