Characterization of performance and disinfection resilience of nonwoven filter materials for use in 3D-printed N95 respirators

Abstract

Additional testing was performed to characterize the filter media properties: thickness, solidity, and effective diameter. An inverted microscope or digital caliper (if >2 mm thick) was used to measure filter thickness. When using the microscope, a sample was supported on its edge between two glass microscope slides and photographed. This was true of single-layer and multi-layer filter media. A Samsung Galaxy S7 (S/N RF8H82NM9KT) was held on the microscope eyepiece using a CNC Supply Microscope Adapter. A 10X ocular and 10X objective were used on the microscope. ImageJ (National Institutes of Health, Bethseda MD) was then used to determine the length of the filter thickness after scaling with a photo of a 1-mm stage micrometer with 100 divisions. Solidity, or "packing density," was determined by cutting 1.3-cm circles from the media with a punch and weighing them on a 6-place

Simple fabrication of an electrospun polystyrene microfiber filter that meetsN95filtering facepiece respirator filtration and breathability standards

“…Additionally, a member of the study team (P.T.O.) used the apparatus described here to test other commercially available filter media (e.g., melt‐blown and polypropylene spunbond‐supported materials), the details and results of which can be found in O'Shaughnessy et al 76 There, only 2 of the 14 filter media tested achieved filtration efficiencies ≥95%, with the rest holding efficiencies around 70%–90%. The two most efficient filter media exhibited pressure drops at 7.5 and 10.6 mm H 2 O, showing comparable performance to those of our PS microfiber filters 76 .…”

“…used the apparatus described here to test other commercially available filter media (e.g., melt‐blown and polypropylene spunbond‐supported materials), the details and results of which can be found in O'Shaughnessy et al 76 There, only 2 of the 14 filter media tested achieved filtration efficiencies ≥95%, with the rest holding efficiencies around 70%–90%. The two most efficient filter media exhibited pressure drops at 7.5 and 10.6 mm H 2 O, showing comparable performance to those of our PS microfiber filters 76 . Thus, based on the performance standards for N95 FFRs, and relative to commercially available materials (electrospun and other), our PS microfiber filters represent a reasonable alternative for N95 FFR development.…”

“…The two most efficient filter media exhibited pressure drops at 7.5 and 10.6 mm H 2 O, showing comparable performance to those of our PS microfiber filters. 76 Thus, based on the performance standards for N95 FFRs, and relative to commercially available materials (electrospun and other), our PS microfiber filters represent a reasonable alternative for N95 FFR development.…”

Elastomeric Respirators for COVID-19 and the Next Respiratory Virus Pandemic: Essential Design Elements

“…During the COVID-19 pandemic, due to the shortage of respirators, there were numerous attempts to construct homemade respirators using three-dimensional printed materials, respiratory therapy equipment, anesthesia circuit filters, and other available components. [49][50][51] This situation revealed the critical shortage of commercially available respiratory protection. To the contrary, elastomeric respirators can be used for prolonged periods of time, and thus provide a durable solution during a pandemic.…”

The fire hazard potential of thermally thin cellulose nonwovens with different overlap configurations

“…3,4 With the outbreak of COVID-19, demand for disposable products such as masks and sterile sheets exceeded supply, which led to a sharp increase in the production of nonwovens as a raw material for certain disposable products. 5,6 A microstructure comparison of nonwovens and conventional fabrics is shown in Figure 1. Nonwovens have a quasi-two-dimensional structure formed by bent filaments, which are produced by melt-blown (MB), spun-bond (SB), and needle punch (NP) synthesis.…”