Microscopy of Woven and Nonwoven Face Covering Materials: Implications for Particle Filtration.

Microscopy of Woven and Nonwoven Face Covering Materials: Implications for Particle Filtration.

Publication date: Jan 22, 2024

A suite of natural, synthetic, and mixed synthetic-natural woven fabrics, along with nonwoven filtration layers from a surgical mask and an N95 respirator, was examined using visible light microscopy, scanning electron microscopy, and micro-X-ray computed tomography (uXCT) to determine the fiber diameter distribution, fabric thickness, and the volume of solid space of the fabrics. Nonwoven materials exhibit a positively skewed distribution of fiber diameters with a mean value of ≈3 μm, whereas woven fabrics exhibit a normal distribution of diameters with mean values roughly five times larger (>15 μm). The mean thickness of the N95 filtration material is 1093 μm and is greater than that of the woven fabrics that span from 420 to 650 μm. A new procedure for measuring the thickness of flannel fabrics is proposed that accounts for raised fibers. uXCT allowed for a quantitative nondestructive approach to measure fabric porosity as well as the surface area/volume. Cotton flannel showed the largest mean isotropy of any fabric, though fiber order within the weave is poorly represented in the surface electron images. Surface fabric isotropy and surface area/volume ratios are proposed as useful microstructural quantities to consider for future particle filtration modeling efforts of woven materials.

Concepts Keywords
650m aerosols
Cotton cloth masks
Future COVID-19
Microscopy fabric
Nondestructive filtration
infectious diseases
microstructure
N95
source control
textiles

Semantics

Type Source Name
disease VO volume
disease MESH COVID-19
disease MESH infectious diseases

Original Article

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