Energy-conversion nano/micromaterial based retinal prostheses for vision restoration

Retinal degenerative diseases result in progressive and profound visual impairment. Retinal prosthesis implantation is a promising strategy for retinal degenerative disease treatment. Conventional retinal prostheses based on electrode arrays have limitations such as low resolution and poor biocompatibility. This review focuses on retinal prostheses using energy-conversion nano/micromaterials, including photovoltaic, piezoelectric, upconversion, and photothermal materials. These materials can convert external energy into neural stimulation signals, enabling wireless or self-powered operation. For instance, photovoltaic materials offer high sensitivity and resolution; piezoelectric materials can harness ultrasound for non-invasive neural stimulation; upconversion materials assist humans in distinguishing multiple spectra of near-infrared light; and photothermal materials can stimulate neurons through near-infrared light with better tissue penetration. In addition, the nano/microscale structure of the retinal prosthesis strengthens the physical and chemical properties and provides more sensitive neuronal signal transmission. Although remarkable progress has been made, challenges like achieving high and stable resolution, ensuring long-term biocompatibility, and optimizing the material-neural tissue interface remain. Future research should focus on developing novel nano/microstructured materials, innovative device designs, and a better understanding of the bio-interface to restore more natural visual function for patients with retinal degeneration.