Effect of Nanofibers on Spore Penetration and Lunar Dust Filtration

The results of two separate studies on biological spore penetration and simulated lunar dust filtration illustrate the use of nanofibers in some nonstandard filtration applications (nanofibers are generally defined as having diameters of less than a micron). In the first study, a variety of microporous liners containing microfibers and nanofibers were combined with cotton-based fabrics in order to filter aerosolized spores. The aerosol penetration resistance of the nanofiber-lined fabrics was measured, and some analysis was conducted of where the particles are captured within the fabric layers. Testing was conducted with aerosolized living spores, in order to evaluate the efficacy of various fabric treatments on spore viability within the fabric layers after exposure. Reported are the results of studies on fabrics with and without a removable electrospun nanofiber liner, and the fate of the spores within the fabric layers. In the second study, noninstrumented filtration testing using simulated lunar dust determined the comparative filtration efficiency of various nonwoven filtration media. Nanofiber witness media, combined with scanning electron microscope images, showed that an electrospun nonwoven filter layer effectively filtered out all the large and fine particles of the simulated lunar dust. PART I. EFFECT OF NANOFIBER LINING ON SPORE PENETRATION CHARACTERISTICS OF WOVEN FABRICS INTRODUCTION Current protective garments have been found to provide acceptable exclusion of aerosolized biological agents, but will only prevent the challenge from penetrating. Once trapped, the biological agent will remain active until the garment is treated with a secondary decontaminating agent. Many recent studies have been involved in the development of materials that will not only trap the biological challenge, but actively inactivate the hazardous material. In the 1980’s the U.S. Army Natick Soldier Center developed an aerosol system to test textiles and membranes for their ability to keep airborne biological materials from penetrating [1, 2]. A new system with modifications was recently designed and tested to expose the test fabrics to aerosolized Bacillus spores and measure the number of spores that remain active after an incubation period. This study reports the results from this aerosol testing system.