A novel method of fabricating convoluted shaped electrode arrays for neural and retinal prostheses

A novel fabrication technique has been developed for creating high density (6.25 electrodes/mm2), out-of-plane, high aspect ratio silicon-based convoluted microelectrode arrays for neural and retinal prostheses. The convoluted shape of the surface defined by the tips of the electrodes could compliment the curved surfaces of peripheral nerves and the cortex, and in the case of retina, its spherical geometry. The geometry of these electrode arrays has the potential to facilitate implantation in the nerve fascicles and to physically stabilize it against displacement after insertion. This report presents a unique combination of variable depth dicing and wet isotropic etching for the fabrication of a variety of convoluted neural array geometries. Also, a method of deinsulating the electrode tips using photoresist as a mask and the limitations of this technique on uniformity are discussed.