Abstract: An optically controllable microelectrode array for stimulating cells within a tissue is disclosed. The array comprises a substrate having a surface. The substrate is adapted to be placed on the tissue with the surface adjoining the cells. The substrate further comprises a plurality of electrodes on the surface in contact with the cells for stimulating the cells. The electrodes are dimensioned such that a first surface area on the electrodes in contact with the cells is essentially smaller than a second surface area on the cells in which the cells may be contacted by the electrodes. An electrical stimulus is exerted from the electrodes to the cells under the control of light impinging on the tissue.

Abstract: A retina implant has a substrate with a surface for applying same to a retina. The substrate comprises electrodes for stimulating cells within the retina. The electrodes are provided on the surface and are exposed to visible light impinging on the retina such that stimuli are exerted on the cells by the electrodes. The implant, further, comprises a photovoltaic layer responsive to non-visible light. The stimuli are locally switched utilizing a voltage generated by the photovoltaic layer.