Fabrication of a Self-Curling Cuff with a Soft, Ionically Conducting Neural Interface.

Direct current (DC) has the potential not only to excite but also to inhibit neurons. This property of DC stimulus has been used for generating peripheral nerve blocks. One translational challenge of DC-based neuromodulation technologies, especially for pain suppression, is that the commercially available cuff electrodes have metal-tissue interfaces that are incapable of delivering DC safely. Passing DC through any metal-tissue interface generates harmful electrochemical products which can damage the target nerve. To address this issue, we present a fabrication process for making self-curling silicone cuffs with paper/agar based, ionically conducting neural interface. We fabricate monopolar as well as bipolar cuffs and demonstrate that the electrode impedances can be easily controlled by modulating the paper/agar channel dimensions. Further, we perform in-vivo implantation of these electrodes on a rat sciatic nerve to qualitatively validate the self-curling action.