Retina-Inspired Nanofluidic Membranes for Underwater Visual Imaging Based on Active Ion Transport

Through evolution, biological organisms have developed ways to sense light using ion channels, which holds several advantages, such as energy efficiency and water resistance, over humanmade optoelectronic devices. Herein, a retina-inspired nanofluidic system is presented with a Janus heterogeneous membrane (J-HM), which can achieve underwater visual imaging through light-driven active ion transport. The J-HMs are obtained through sequentially assembled WS2, and a kind of metal-organic framework nanosheets via the reaction between 2,3,6,7,10,11-hexahydroxytriphenylene hydrate (HHTP) and Cu2+ (Cu-HHTP). Due to the formed intramembrane electric field caused by the efficient charge separation under illumination, a photovoltaic driving force is generated for active ion transport from Cu-HHTP to WS2. Furthermore, the unidirectionally active ion transport can be enhanced by self-diffusion under a concentration gradient. The J-HM with a single-pixel design shows a nearly linear response with light intensity and has enough resolution for basic object recognition as well as a long-term memory after data processing using a defined pixelated matrix, which can pave an avenue for designing more intelligent sensing systems. A retina-inspired nanofluidic membrane with a Janus heterogeneous structure is constructed through sequentially assembled photoelectric nanosheets. Due to the efficient charge separation induced intramembrane electric field under illumination, a photovoltaic driving force is generated for active ion transport, which can be further enhanced by self-diffusion under a concentration gradient. Finally, it can achieve self-powered underwater object recognition. image