Micropleated Nanofibrous Filters for High‐Efficiency Submicron Aerosol Filtration: A Comparative Study with Chemical, Biological, Radiological, and Nuclear Gas Mask Filters

Electrospinning is a versatile technique for producing polymer nanofibrous fabrics with enhanced functionalities, making it attractive for next‐generation respiratory protection. A major limitation of electrospun filters designed for submicron aerosol capture at ≥99.99% efficiency is their comparatively high breathing resistance relative to conventional glass fiber and expanded polytetrafluoroethylene (ePTFE) media. To address this limitation, this study introduces micropleated filters made by multiple‐jet needleless electrospinning, where nanofibers are deposited onto uniaxially prestretched textile substrates. Upon release, the substrates contracted to their original dimensions, forming densely packed micro‐pleats that increased the effective surface area without altering the overall filter size. Prestretching the substrate to 225% prior to nanofiber deposition produced a twofold increase in quality factor compared with nanofiber mats deposited on unstretched substrates, driven by improved submicron aerosol filtration and reduced pressure drop. The micro‐pleated filters achieved quality factors exceeding 0.26 Pa −1 , comparable to high‐performance ePTFE‐based military gas mask filters and more than three times higher than glass fiber filters. The micropleated filters also outperformed ePTFE filters in capturing and releasing aerosolized MS2 bacteriophage. These findings demonstrate that micropleated electrospun filters offer a promising pathway toward high‐efficiency, multifunctional filtration systems applicable to defense, healthcare, and environmental protection.