Cloth Masks through SEM imaging

Last updated: 2021-11-18  |  275 Views  | 

Cloth Masks through SEM imaging

With the current COVID-19 pandemic, face masks have become a part of everyone's daily life to help slow the spread of the virus. The US Centers for Disease Control and Prevention released findings that double-masking can be an effective way to reduce the transmission of the coronavirus that causes Covid-19. The method of double masking recommended by CDC is to wear a cloth mask on top with a disposable medical mask underneath. The cloth mask will add up layers and pin down the side gaps of the medical mask improving performance and reducing SARS-CoV-2 transmission and exposure.

Cloth Masks

Cloth Masks can be made from a variety of fabrics and many types of cloth masks are available. Nowadays, Cloth masks are not just a product or a protective equipment,  they are also a tool to showcase innovation potential of the life wear. Some of the products prioritize high-quality fabrics, adequate ventilation, and a delicate texture. Some claim to feature a coating (Nano Hydrophobic Filament) that prevent water droplets from penetrating which is helpful for reducing the spread of germs from coughing or sneezing.

SEM imaging

In this Cloth Mask through SEM imaging experiment. We selected cloth masks that is on the Thai market by popular brands with claims that the cloth masks can be use through 30 wash cycles to see close images and changes through washings.

Our Hitachi Scanning Electron Microscope Model SU3900 captured these pictures at 1000x magnification to see the physical properties of new mask and observe how the fibers of the masks change after washing (Wash 30 times by hand with detergent).


BrandCondition 
Thread shape
Thread size
Woven density
Coating
Brand A
before wash
round
thin with  moderate size consistency
High density
high density  and spread thoroughly
after 30 washes
some were damaged
expanded
moderate loss of density
some washed away
Brand B
before washroundthick with high size consistencyhigh density  
moderate density  and spread thoroughly
after 30 washes
maintained shapemaintained sizemaintained high density
mostly washed away
Brand C
before washuniquely flattenedthick with high size consistencyhigh density
high density and spread thoroughly
after 30 washes
mostly maintainedexpandedmoderate loss of density
mostly washed away


 
BrandCondition 
Thread shape
Thread size
Woven density
Coating
Brand Dbefore washroundthin with hign size consistencyhigh densitymoderate density and spread thoroughly
after 30 washesmaintained shapemaintained sizemaintained high densitymostly washed away
Brand Ebefore washround (distort and split)uneven sizelow density  low density and not spread thoroughly
after 30 washessome were damagedexpandedmoderate loss of densitymostly washed away 
 
SEM photos show the characteristics of fibers and coatings, and 4 out of 5 brands have decentmask quality. The quality of the fibers in the mask is reduced after washing, and the coating material is noticeably lost. Washing causes varying degrees of deterioration and coating loss in each brand of mask.
 
Surfaces can be analyzed using Scanning Electron Microscopy at magnifications ranging from hundreds to millions of times. EDS Analysis also provides elemental and chemical analysis of a sample within the SEM. 
 

 

 

 

Reference

Brooks JT, Beezhold DH, Noti JD, et al. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021. MMWR Morb Mortal Wkly Rep 2021;70:254–257. DOI: http://dx.doi.org/10.15585/mmwr.mm7007e1

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