Finite Element Analysis of Planar Micromachined Silicon Electrodes for Cortical Stimulation

This paper describes a three dimensional (3D) finite element model of micromachined stimulating microelectrode arrays for cortical stimulation. These micromachined probes, known as Michigan probes, are lithographically defined in geometry and fabricated though mostly standard silicon processing technology. However, the fabrication process requires the highly conductive boron-doped shanks, which provide mechanical support for the electrode array, to be grounded especially in active electrodes that incorporate integrated circuits on the same chip. We have examined the effects of grounding this portion (body) of the electrode arrays using finite element analysis (FEA) and drawn a few conclusions about their design. Further, using information gained from our FEA models, we evaluate the current distribution and volume of the excited tissue in a proposed design that would increase the density of electrodes in a given volume and provides greater precision for targeted stimulation