Bio-Inspired Design of Robust, Transparent Nanofibrous Air Filters for High-Efficiency Particulate Matter Capture

Transparent air filters (TAFs) have attracted considerable attention for air purification and personal protection. However, conventional TAFs improve high light transmittance by minimizing fiber diameter and reducing filter thickness, which compromises mechanical strength and remains restricted by the trade-off between filtration efficiency and pressure drop. Inspired by the heterogeneous vein-membrane structure of dragonfly wings, a bio-inspired TAF (B-TAF) with enhanced mechanical and filtration performance is designed through dual-nozzle electrospinning and spatially controlled electric-field deposition. Enabled by cross-scale fiber assembly and spatially resolved deposition, the B-TAF possesses a multi-dimensional architecture, comprising 1D bimodal nanofiber diameter distribution, 2D irregular in-plane spatial arrangement of dense and sparse nanofiber layer regions, and 3D fluffy porous nanofiber architecture. This precisely engineered architecture features high visible light transmittance (>70.0%), outstanding filtration efficiency (>99.5% for both PM_0.3 and PM_1.0), and exceptionally low pressure drop (<80.0 Pa), effectively overcoming conventional transparency-strength and efficiency-pressure-drop trade-offs. Furthermore, the B-TAF exhibits superior mechanical robustness, with a tensile strength of 5.3 MPa and an elongation at break of 232%, ensuring stable long-term operation under practical conditions. This study presents a scalable manufacturing approach, offering a viable pathway toward the practical application of high-performance multifunctional TAFs.