A Preliminary Study of the Connective Tissue Sheath Removal Device to Facilitate Insertion of Peripheral Nerve Interfaces

Abstract

In inserting neural interfaces to obtain neural signals from peripheral nerves, the connective tissue sheath of the peripheral nerve, which protects the peripheral nerves, makes it challenging to insert interfaces. Therefore, to penetrate the connective tissue sheath and insert the interface into the nerve, the mechanical properties of the interface should be higher than those of the nerve fibers, or a high-stiffness insertion device should be additionally used, which can cause nerve damage during the insertion process. In this study, we propose a connective tissue sheath device to partially remove the connective tissue sheath as a method for inserting low-stiffness neural interfaces. The effect of collagenase on peripheral nerves to remove the connective tissue sheath was investigated by ex-vivo experiments, and the amount of the removed connective tissue sheath was analyzed. An in-vivo animal experiment was conducted using the developed connective tissue sheath removal device, and the amount of connective tissue sheath was determined at 15-minute intervals using an optical coherence tomography (OCT) device. Melamine foam is used as a carrier to react 5 mg/mL of collagenase solution with peripheral nerves, and the melamine foam is designed to move back and forth according to the scanning situation. As a result, the connective tissue sheath reacts with the collagenase, and the residual amount is reduced from approximately 96 μm to approximately 29 μm after 1 hour.Clinical Relevance— This study demonstrates a connective tissue sheath partially removed for inserting a low-stiffness neural interface in an in-vivo environment using collagenase.