Progress in bio-inspired porous membranes

Porous membranes are one of the research hotspots in the domain of separation materials and have been widely utilized in various fields (such as water treatment, energy, biological medicine) due to their high separation efficiency, low cost, and non-secondary pollution, etc. However, there still exist many challenges in their application process, such as low selectivity, poor anti-fouling, poor responsive, critically limiting its development. Recently, bio-inspired porous membranes offer a brand-new idea for solving those problems and are becoming one of the most exciting research areas in porous membranes field. Compared with traditional porous membranes, bio-inspired porous membranes, designed by imitating the unique pore structure and separation performance of biological membranes, display distinct advantages in selectivity performance, antifouling property, intelligent gating property, and intelligent response property. This critical review detailedly presents the recent developments of bio-inspired porous membranes with multi-scale pore structure. In this paper, the first section mainly gives a brief introduction to the pore structure, separation selectivity, and response property of both nano-scale biological membranes and micro-scale biological membranes. Among numerous nano-scale biological membranes, the most concerning to date include cell membrane with ion channel, cell membrane with aquaporin, and glomerular filtration membrane. Ion channel embedded within cell membrane provides ion selectivity, ion current rectification, and ion gating characteristics to cell membrane. Inspired by this, novel porous membranes with excellent ion selectivity are developed for regulating ion permeation. Meanwhile, aquaporin can let the passive transport of water across cell membrane while simultaneously excluding ions, offering a new strategy for designing bio-inspired porous membrane for high efficiency desalination. Glomerular filtration membrane with the nano-scale pore can prevent the filtration of blood cells and platelets, and removes most of nano-scale molecules from the blood. Inspired by its unique filtration property, various bio-inspired porous membranes have been designed for clinical kidney replacement treatment. Additionally, the micro-scale porous membranes in nature mainly contain alveolar membrane with intelligent gating property and leaf stomata membrane with intelligent response property. By imitating the alveolar membrane, liquid gating porous membranes with intelligent gating property are developed, achieving for controlling the movement of fluids, vapours, and solids. Learning from leaf stomata membrane, intelligent responsive porous membranes are also designed, and can be applied in controllable transmission. For preparing the high performance of bio-inspired porous membranes, the designed strategies are also introduced in detail. The second section has further outlined the applications of bio-inspired porous membranes in water treatment, energy, biological medicine, and substance detection. In water treatment field, aquaporin-based bio-inspired porous membrane possesses better desalination performance than traditional porous membrane. In energy field, bio-inspired porous membranes offer unique ions selectivity and ions transport, thus enhancing energy conversion efficiency in salinity gradient energy capture. In biological medicine field, alveolar-like liquid gating composite membranes can be utilized for fabricating artificial blood vessel with anticoagulation and drug release properties. Moreover, bio-inspired porous membranes with porous support and thin separation layer are demonstrated as hemodialysis membranes for the treatment of kidney disease. In substance detection, visual and low power consuming chemical detection of specific analytes can be achieved by liquid gating composite membrane. In the last section, future challenges in theory, preparation technology, and application of bio-inspired porous membrane are presented, providing an overview of the various solutions. Ultimately, continued efforts to relative research and materials development will promote the rapid development of bio-inspired porous membrane.