The death of viruses through masks in a Swiss research

From EMPA researchers an innovative method that uses an artificial saliva fluid colored red and pushed under pressure into the tissues

Virus death: Only a few viruses manage to reach the innermost layer of a fabric mask: A picture (scanning electron microscopy, post-color) shows a textile fiber with salt crystals (light blue) and viruses the size of approx. 100 nanometers (green)
Only a few viruses manage to reach the innermost layer of a fabric mask: An image (scanning electron microscopy, post-color) shows a textile fiber with salt crystals (light blue) and viruses about 100 nanometers in size (green )
(Photo: EMPA)

Using a new analytical method, the EMPA researchers studied the transit of viruses through face masks, the popular so-called “masks”, and compared their different failures in the filter layers of different types of masks.
“The new method should now accelerate the development of surfaces capable of killing viruses”, wrote the research team in an article in the journal Scientific Reports.

The article "A new inactivated virus system (InViS) for a rapid and economic assessment of viral disintegration" of the journal "Scientific Reports" (in English)

Death of viruses: a virus photographed and represented in green in the context of a study on masks (Photo: EMPA)
A virus photographed and represented in green as part of a study on masks
(Photo: EMPA)

It's necessary to keep germs away, resist splashes of saliva and let the air filter

Using high pressure, an apparatus pushes a red-colored artificial saliva fluid with test particles through an elongated mask.
In this way, the researchers simulate the droplet infection process.
The new method, developed by the Swiss Federal Laboratories of Materials Science and Technology, is currently used by certified test centers to ensure the quality of fabric face masks, because a safe and effective protective "mask" must meet demanding requirements.
It must keep germs away, resist splashes of saliva and at the same time allow air to pass through.
Now the EMPA researchers are going one step further: “Images taken with a scanning electron microscope show that some virus particles manage to find their way into the innermost layer of the mask, close to the face. However, such photographs do not always reveal whether these viruses are still infectious.", explains Peter Wick of the Particles-Biology Interactions Laboratory at EMPA in St. Gallen.

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Death of viruses: only a few viruses manage to reach the innermost layer of a fabric mask: an image (scanning electron microscopy) shows a textile fiber with salt crystals and viruses about 100 nanometres in size, highlighted by the string of measurement (Photo: EMPA)
Only a few viruses manage to reach the innermost layer of a fabric mask: An image (scanning electron microscopy) shows a textile fiber with salt crystals and viruses the size of about 100 nanometres, highlighted by the measuring string
(Photo: EMPA)

Which barrier components need to be more efficient and “where” exactly?

What is the goal of the researchers? They want to find out where exactly a virus particle is retained within a multilayered face 'mask' during droplet infection, and which components of the mask should be most efficient.
“We needed new analytical methods to accurately understand the protective function of newly developed technologies such as anti-virus coatings”, explains René Rossi, EMPA researcher at the Laboratory for Biomimetic Membranes and Textiles in St. Gallen.
After all, this is precisely one of the objectives of the "ReMask" project, in which research, industry and healthcare experts collaborate with the Swiss Federal Laboratories of Materials Science and Technology in the fight against the pandemic to develop new concepts for better face masks, more comfortable and more sustainable.

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A process based on a dye, rhodamine R18, which emits pigmented light

The new process is based on a dye, rhodamine R18, which emits pigmented light.
Inactivated, harmless test viruses are used, which are mated to R18 and thus become “dying beauties”: they light up as soon as they are damaged.
“Fluorescence reliably, quickly and cheaply indicates when viruses have been killed”, explains the scholar.
Based on how brightly a layer of the mask lights up, the team found that, for cloth and hygiene masks, most viruses fail in the mid-zone between the inner and outer layers of the mask.

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Death of viruses: a virus photographed and represented with particle measurements
A virus photographed and represented with particle measurements
(Photo: EMPA)

The third of the six layers of an FFP2 is the best killer of infectious agents, and more

In FFP2 masks, the third of the six layers is the one that lights up the most: again, the middle layer traps a particularly large number of viruses.
The researchers recently published their findings in the journal "Scientific Reports": this data and information can now be used to optimize face masks.
Additionally, the new process may accelerate the development of virus-killing surfaces.
“Surfaces with antiviral properties must comply with certain ISO standards, which involve laborious standard testing”Wick explains.
The fluorescence method of the researchers of theEMPAinstead, it could be a simpler, faster and cheaper method of determining whether a new type of coating can reliably kill viruses, supplementing current standards.
This would be of interest both for smooth surfaces, such as those on worktops or handles, and for fabric coverings with a porous surface, such as masks or filter systems.
With the new method, this knowledge could be integrated into the development process of technical and medical applications at an early stage.
According to Peter Wick, this will speed up the introduction of new products, as only promising candidates will have to undergo time-consuming and costly standardization tests.

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Death of viruses: for Peter Wick, EMPA scientist,
For Peter Wick, EMPA scientist, "a new process can accelerate the development of surfaces that kill viruses" (Photo: EMPA)