Multi-phasic microphotodetector retinal implant with variable voltage and current capability

A retinal implant for electrically inducing formed vision in an eye, the retinal implant comprising:

• a plurality of microphotodetector pixels, each of the plurality of microphotodetector pixels spaced apart from any adjacent microphotodetector pixels and each of the pixels embedded in a lattice-like mesh, wherein each of the microphotodetector pixels comprises:
• at least one first layer microphotodetector pair for receiving light incident on the eye, each microphotodetector pair comprising:
• a PiN microphotodetector and a NiP microphotodetector, wherein the P-portion of the PiN microphotodetector and the N-portion of the NiP microphotodetector are aligned on a first end, and the N-portion of the PiN microphotodetector and the P-portion of the NiP microphotodetector are aligned on a second end;
• and
• a common electrode in electrical communication between the P-portion and the N-portion of the first end of the microphotodetector pair;
• and
• a gain adjustment layer having a first side and a second side, the first side having a first portion electrically connected in series with the second end of at least a portion of the plurality of first layer microphotodetector pairs, and a second portion integrally formed with the first portion and extending away from the first portion, wherein the second portion is oriented to receive light incident on the eye.

A retinal implant for electrically inducing formed vision in an eye, the retinal implant comprising:

• a first layer comprising a plurality of microphotodetector pairs, each microphotodetector pair comprising:
• a PiN microphotodetector and a NiP microphotodetector, wherein the P-portion of the PiN microphotodetector and the N-portion of the NiP microphotodetector are aligned on a first end, and the N-portion of the PiN microphotodetector and the P-portion of the NiP microphotodetector are aligned on a second end;
• and
• a common electrode in electrical communication between the P-portion and the N-portion of the first end of the microphotodetector pair;
• a first common electrode strip in electrical contact with the N-portions of the second end of each of the plurality of PiN microphotodetectors of the microphotodetector pairs;
• a second common electrode strip in electrical contact with the P-portions of the second end of each of the plurality of NiP microphotodetectors of the PiN/NiP microphotodetector pairs;
• a second layer photodetector gain adjustment layer comprising a first end and a second end, the first end comprising a first portion electrically connected in series with the common electrode strips of both the N-portion and P-portion of the second end of the first layer of microphotodetector pairs, and a second portion integrally formed with the first portion extending away from the first portion and oriented to receive light incident on the eye;
• and
• a common electrode plane for the second layer photodetector gain adjustment layer in direct electrical contact with the second end of both the first portion and the second portion of the photodetector, gain adjustment layer, the common electrode plane serving as the electrical ground of the retinal implant.