High-Throughput Electrospinning System| Advances in Nanofiber Filtration Membranes: From Principlesto Intelligent Applications

Dr. Shi Shuo (PolyU), Prof. Wang Xungai (PolyU)/Prof. Hu Jinlian (CityU) AFM: Advances in Nanofiber Filtration Membranes: From Principles to Intelligent Applications

Air pollution is a silent killer, posing major health threats affecting over 80% global population and causing respiratory/cardiovascular diseases. Electrospun nanofiber filtration membranes have achieved significant progress due to large surface area, structural adaptability, and self-polarization properties.

Recently, Dr. Shi Shuo and Prof. Wang Xungai (Hong Kong Polytechnic University)/Prof. Hu Jinlian (City University of Hong Kong) published a review on nanofiber filtration membrane advances from principles to intelligent applications in Advanced Functional Materials as "Advances in Nanofiber Filtration Membranes: From Principles to Intelligent Applications".

Fig.1 Electrospun nanofiltration materials, structures, and functionalization

This review examines recent developments through four key aspects: filtration principles, material design, structural innovation, and functionalization. First, classical filtration mechanisms are discussed, followed by sustainable materials and green technologies for advanced filtration. Fiber structure design innovations are thoroughly investigated, highlighting nanofibers with high roughness, ultrafine diameters, and bimodal distributions. Nature-inspired designs have yielded high-performance biomimetic membranes, with current focus on durable antibacterial/antiviral functionality and intelligent systems with physiological signal detection. Finally, challenges like new filtration mechanisms, green preparation technologies, and reusable intelligent systems are emphasized. Solutions will open new possibilities for biodegradable membranes, smart wearables, and advanced healthcare.

Fig.2 A) Global PM2.5 concentrations and pollution-related deaths; B) Disease mortality percentages; C) Filtration mechanisms

From filtration mechanisms, low pressure drop and high efficiency remain primary targets. With advanced materials, traditional non-degradable petroleum-based materials are transitioning to sustainable alternatives, while green electrospinning gains attention. Solvent-free electrospinning represents future trends.Structural designs include ultrafine networks, high-roughness fibers, and bimodal distributions. Biomimetic concepts like spider silk, dragonfly wings, and mussel wet-adhesion have inspired efficient membranes. Deeper understanding of mechanisms has proposed residence time theory, air slip theory, and triboelectric-enhanced filtration.Current demands shift toward multifunctional systems, especially integrating comfort, physiological monitoring, human-machine interaction, and transparent aesthetics. However, challenges remain:

A) Innovative mechanisms: Enhancing fiber charge/surface area improves efficiency but may not suit reusable smart systems. Performance degrades in high humidity, metal dust, or temperature. New mechanisms/materials are needed for diverse scenarios.

B) Stability/efficiency: Electrospinning's inherent challenges include mass production and stable fiber control. Needleless, air-assisted, and melt electrospinning can promote industrialization and eco-friendly production.

C) Sustainability: Green solvent development progresses slowly. Few polymers dissolve well in eco-friendly solvents like ethanol/water. Research on green polymer dissolution theory remains scarce.

Overall, nanofiber filtration advances rapidly through green materials, biomimetic structures, and innovative theories. Current nanofiber masks integrate mid-infrared permeability, antibacterial/antiviral properties, and respiratory monitoring. However, green electrospinning, filtration mechanisms, and special-scenario applications receive insufficient attention. Future multifunctional membranes will benefit from wearable tech, flexible electronics, and sustainable materials.

Fig.3 A) Fiber-based filtration history; B) Publication trends (Web of Science)

Fig.4 Future industrial solvent recycling systems

Fig.5 Nature-inspired membranes: A) Spider-web; B) Dragonfly-wing; C) Honeycomb; D) Mussel-adhesion

Fig.6 A) Smart mask schematic for respiratory monitoring; B) Infrared-detected mask temperature; C) Smart respirator; D) Physiological signal monitoring; E) Portable design with detection functions

Fig.7 Key elements, challenges, and development paths of advanced nanofiber filtration systems