Fabrication methods for a flexible device for retina prosthesis are described. Layered structures including an array of pixel units may be formed over a substrate. Each pixel unit may comprise a processing circuitry, a micro electrode and a photo sensor. A first set of biocompatible layers may be formed over the layered structures. The substrate may be thinned down to a controlled thickness of the substrate to allow bending of the substrate to the curvature of a retina. A second set of biocompatible layers may be formed over the thinned substrate. The second set of biocompatible layers may be in contact with the first set of biocompatible layers to form a biocompatible seal wrapping around the device to allow long-term contact of the device with retina tissues. Micro electrodes of the pixel units may be exposed through the openings of these biocompatible layers.