Arrowhead-shaped micro-electrode array on polyimide substrate for retinal prostheses enabling close approach to target cells

In this paper, an undulated micro-electrode array (MEA) on polyimide is fabricated and evaluated for retinal prosthesis. The undulated MEA consists of the individual micro-electrodes having arrowhead shapes and varying heights of 50 ~150 mum. The proposed device is implanted in a rabbit eye, and an optical coherent tomography (OCT) image is taken. The OCT image shows that the implanted MEA contacts conformably with the retinal layers. The electrically evoked cortical potential (EECP) is recorded for the comparison of the proposed micro-electrode and a conventional planar micro-electrode. The EECP amplitude of the proposed device is higher than that of a conventional planar micro-electrode. We conclude, based on the conformal contact data, in vivo EECP results, and in vivo biocompatibility test, that the proposed 3-D undulated MEA has a high potential for clinical applications.