We present the concept of a novel epiretinal prosthesis, consisting of a foil-based, miniaturized electronics with wireless optical energy and signal transmission and integrated electrostimulation. The aim is achieving a wideangle projection to create a large visual field. The implant having a diameter of 14 mm consists of a mosaic-like array of thinned silicon-based photodiodes combined with a polyimide foil. This thin implant, realized on a flexible foil for the first time, adapts to the

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... ture of the eye. Thin-film stimulation electrodes on the foil are electrically connected to the photodiodes. The influence of the electrode geometry on the electrical current density at the location of electrostimulation is investigated by computer simulations. First experiments towards realization of via holes in a 10 μm thick polyimide layer were successful and led to vias with inclined sidewalls and rounded openings. This shape is advantageous concerning uninterrupted conductor paths leading from the photodiodes to the stimulation electrodes.