Fabrication and Characterization of Plateau-structured Electrodes for Retinal Prostheses with Improved Stimulation Selectivity.

Retinal prostheses have been developed to restore vision in patients with photoreceptor degeneration, with neural interfaces playing a crucial role in effective stimulation. Conventional planar electrodes, commonly used in subretinal prostheses, exhibit limitations such as restricted cell-electrode contact and uncontrolled current dispersion, which reduce stimulation efficiency. To address these issues, we developed a novel plateau-structured electrode designed to enhance contact with retinal cells and improve localized stimulation. The electrodes were fabricated using a post-forming process with cyclic olefin copolymer (COC) thermoforming and lamination, ensuring structural stability and reliable encapsulation. Impedance spectroscopy confirmed the electrical performance of the electrodes, with an average impedance of approximately 100 Ω at 1 kHz, demonstrating their suitability for neural stimulation. Future studies will focus on cell adhesion experiments with NIH3T3 fibroblasts to assess biocompatibility and computational modeling using COMSOL Multiphysics® to simulate electric field distribution and optimize stimulation efficiency. The proposed plateau-structured electrode presents a promising approach to overcoming the limitations of conventional planar electrodes in subretinal prostheses. The findings contribute to the advancement of bioelectronic interfaces, with potential applications extending beyond retinal prostheses to neural stimulation devices requiring precise and stable cell-electrode interactions. Furthermore, the structural and fabrication methodologies developed in this study may be applicable to a wide range of biomedical devices where improved electrode stability and selectivity are critical.