Reusability Comparison of Melt-Blown vs Nanofiber Face Mask Filters for Use in the Coronavirus Pandemic

Abstract

Shortage of face masks is a current critical concern since the emergence of coronavirus-2 or SARS- . In this work, we compared the melt-blown (MB) filter, which is commonly used for the N95 face mask, with nanofiber (NF) filter, which is gradually used as an effective mask filter, to evaluate their reusability. Extensive characterizations were performed repeatedly to evaluate some performance parameters, which include filtration efficiency, airflow rate, and surface and morphological properties, after two types of cleaning treatments. In the first cleaning type, samples were dipped in 75% ethanol for a predetermined duration. In the second cleaning type, 75% ethanol was sprayed on samples. It was found that filtration efficiency of MB filter was significantly dropped after treatment with ethanol, while the NF filter exhibited consistent high filtration efficiency regardless of cleaning types. In addition, the NF filter showed better cytocompatibility than the MB filter, demonstrating its harmlessness on the human body. Regardless of ethanol treatments, surfaces of both filter types maintained hydrophobicity, which can sufficiently prevent wetting by moisture and saliva splash to prohibit not only pathogen transmission but also bacterial growth inside. On the basis of these comparative evaluations, the wider use of the NF filter for face mask applications is highly recommended, and it can be reused multiple times with robust filtration efficiency. It would be greatly helpful to solve the current shortage issue of face masks and significantly improve safety for front line fighters against coronavirus disease.

An overview of filtration efficiency through the masks: Mechanisms of the aerosols penetration

“…Reusability of melt-blown (MB) filter, which belongs to the N95 face mask and nanofiber filter, by considering filtration efficiency, airflow rate, surface, and morphological properties, evaluated after two types of cleaning treatments [ 54 ]. It has been reported that the performance of the MB filter was highly decreased after treatment with ethanol, while the NF filter represented consistent high filtration efficiency.…”

Disinfection Treatments of Disposable Respirators Influencing the Bactericidal/Bacteria Removal Efficiency, Filtration Performance, and Structural Integrity

“…Complete suppression of bacterial growth after 5 min immersion [22] NA [7,19] Complete bactericidal efficiency of S. subtilis and E. coli [18] Isopropanol Decrease in particle filtration efficiency (over 5%) NA [11,17] Significant drop in oily aerosol filtration efficiency after 2 min immersion (up to around 40%) NA [9] Detergent -laundering Significant drop in particle filtration efficiency after soap solution soaking for 2 min (up to around 39%) NA [15] The particle filtration of an electret media is attributed to the mechanical capture and the electrostatic attraction of particles [31,32]. Many previous studies associated the deteriorated performance of disinfection-treated respirators with the loss of electrostatic charges [7,9,11,15,[17][18][19]22,25], yet the direct evidence of charge deterioration was often missing. Additionally, it has hardly been examined for the effect of treatment on the structural integrity of the filter media, which may affect the resistance of respirators.…”

“…As a contingency strategy for the capacity crisis of disposable respirators, the Centers for Disease Control and Prevention and the National Institute of Occupational Safety and Health announced the guidelines of potential disinfection methods for the reuse of disposable respirators, which include the application of ultraviolet (UV) germicidal irradiation, vaporous hydrogen peroxide (VHP), and moist heat [ 5 ]. Table 1 shows the summary of previous studies on respirator disinfection methods [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. As for the bactericidal efficiency, autoclaving, UV irradiation, and chemical solvent treatments using bleach, ethanol, and VHP showed up to a 99% reduction of tested bacteria or virus [ 21 , 25 , 26 , 27 , 28 , 29 , 30 ].…”

Design of a self-powered triboelectric face mask

“…Even house hold available material such as elastic T-shirt, quilting cotton, assorted fibers were used to fabricate face mask that indicates besides custom made nanofiber based mask, textile based masks are also gains prevalence due to its cost effectiveness and reusable possibilities along with adequate filtration abilities [ 52 ]. Recent study also been taken where customized made nanofibers made mask were also investigated where the reusabilities has also given one of the prime focus [ 53 ].…”