Finite element analysis of electric field of extracellular stimulation of optic nerve with a spiral cuff electrode / 生物医学工程学杂志

ABSTRACT

In order to study the underlying electrode-nerve functional mechanism, optimize the electrode design and guide the prosthesis application, we applied finite element method to analyze the spatial distribution of electric field generated by optic nerve electrical stimulation with spiral cuff electrode. A macroscopic cylindrical model of optic nerve was elaborated, taking into account of electrode contact configurations and possible variations of the thickness of cerebrospinal fluid (CSF). By building an appropriate mesh on this model and under some boundary conditions, the finite element method was applied to compute the 3D electric field generated by the electrode with finite element software COMSOL Multiphysics. The stimulation results indicated that, under the same conditions of stimulation, the longitudinal tripolar electrode structure could generate larger current density than that of biopolar electrode structure (located in the opposite of nerve trunk). However biopolar electrode structure requirs less leads, and is more easily implanted. By means of parametric sweep, the results suggest that, with the increase of the CSF thickness and a higher conductivity of CSF than those of other tissues, the distribution of electric field generated by electrodes is extended but scattered, and the diffuse current distribution makes nerve stimulation less effective.