A Photoelectrochemical Retinomorphic Synapse

Abstract Reproducing human visual functions with artificial devices is a long‐standing goal of the neuromorphic domain. However, emulating the chemical language communication of the visual system in fluids remains a grand challenge. Here, a “multi‐color” hydrogel‐based photoelectrochemical retinomorphic synapse is reported with unique chemical‐ionic‐electrical signaling in an aqueous electrolyte that enables, e.g., color perception and biomolecule‐mediated synaptic plasticity. Based on the specific enzyme‐catalyzed chromogenic reactions, three multifunctional colored hydrogels are developed, which can not only synergize with the Bi₂S₃ photogate to recognize the primary colors but also synergize with a given polymeric channel to promote the long‐term memory of the system. A synaptic array is further constructed for sensing color images and biomolecule‐coded information communication. Taking advantage of the versatile biochemistry, the biochemical‐driven reversible photoelectric response of the cone cell is further mimicked. This work introduces rich chemical designs into retinomorphic devices, providing a perspective for replicating the human visual system in fluids.