gms | German Medical Science

Objective: Retinitis Pigmentosa is a genetic disorder characterized by the progressive degeneration of photoreceptors within the retina. To restore vision, prosthetics have yielded encouraging results, but with limited spatial resolution and field of view. Integrating an active microelectrode array embedded in a flexible foil presents a promising approach to improve the resolution of the implants.

Materials and Methods: An origami-inspired epiretinal implant was developed to enhance the field of view and to reduce complications during surgical procedures. For enhanced spatial resolution, a matrix of 32×32 electrodes was fabricated on silicon-on-insulator (SOI) wafers using the top silicon as an active layer.

Results and Discussion: The flexibility of the epiretinal implant is achieved through a bi-layer of polyimide (PI), consisting of 3 µm-thick layers. Embedded within these layers are 30 µm-diameter gold microelectrodes and 4 µm-thick interconnecting wires, fabricated via electroplating to ensure mechanical robustness. Although the implant integrates 480 microelectrodes, characterization was limited to 32 electrodes due to constraints by one-to-one wiring. To overcome these limitations and enhance spatial resolution, a high-density 32×32 microelectrode array was developed as a prototype. This array will be encapsulated within the bi-layer PI, offering a scalable solution for an enhanced field of view. The proposed design aims to significantly improve visual restoration by increasing the electrode density while maintaining the mechanical flexibility required for integration into the bowl-shaped retina.

Acknowledgement: This work was funded by the Deutsche Forschungsgemeinschaft (DFG), GRK2610/1 project number 424556709