Engineers at Virginia Commonwealth University (VCU) in Richmond, Virginia, have designed a new face mask that uses chemical reactions and electrical charges to kill microbes, including the coronavirus particle.
‘The problem with almost all commercially available masks is that they are passive devices. They capture airborne pathogens, but they don’t kill them,’ said Wei-Ning Wang, an associate professor in the Department of Mechanical and Nuclear Engineering in VCU’s College of Engineering.
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While screening out microbes can be effective strategy, he said, ‘in high-risk areas such as hospitals, a lot of airborne bacteria and viruses are collected on the mask’s surface, so there is an elevated risk of contamination, especially while removing or changing masks.’
The mask that Wang and his colleagues are developing consists of three layers. The ‘user-friendly’ innermost layer absorbs water vapour. ‘Human exhalation is saturated with water vapour, so it has 100 per cent relative humidity,’ Wang said. ‘This means that the vapour will condense inside the face mask, causing discomfort.’ A mask that effectively absorbs this vapour will keep the wearer cooler and dryer, and will stop glasses fogging up.
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The middle layer catches virus particles with the same efficiency as N95 masks, but most particles won’t make it past the outer layer, which is made of electro-spun nanofibres embedded with nanocrystals that contain an antibacterial and antiviral ammonia compound found in many detergents.
The nanofibres also carry a positive electrical charge, which helps them to attract pathogens, which are typically negatively charged. When a pathogen adheres to the nanofibre, the resulting pressure disrupts the pathogen’s membrane and leads to cell death.
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All of the chemicals and other components in the material are non-toxic, low cost and reusable.
The team is now attempting to reduce the time needed for the mask’s outer layer to kill pathogens, which currently stands at between 30 minutes and an hour, and find further cost savings so that the mask can be produced at scale when it has been commercialised.
While the team’s innovations are particularly relevant in the era of COVID-19, Wang believes that they also have wider benefits for health care workers. ‘The risk of hospital-acquired infections is always high. In addition, health care workers need to wear face masks all day,’ he said. ‘So our group wants to produce a mask for them that truly mitigates that risk and is comfortable to wear.’
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The research has been published in Environmental Science: Nano.