Yanbo Liu, School of Textile Science and Engineering, Wuhan Textile University, Wuhan 430200 China
Since COVID-19 broke out worldwide, many measures have been taken to protect people from being infected by this deadly SARS like virus, among which, facial masks are considered as the most effective tool to combat COVID-19. COVID-19 imparts worldwide deadliest threats due to high transmission of virus from human to human . To protect from virus transmission, all kinds of facial masks have been used by people in the world, including the absorbent cotton gauze mask, woven/knitted mask, disposable medical mask, medical surgical mask, medical protective mask (including N95, etc.), as well as PM2.5 protective masks (KF94,KN95,N95, etc.) .
Recently, masks with higher protection standards such as FFP3, which has both particulate and oil matter protective functions, are highly demanded in the global market for the campaign against COVID-19. However, the commonly used masks such as the cotton gauze masks, disposable medical masks, and even the medial surgical masks cannot protect from COVID-19 virus effectively, which has only the size of 80~120nm in diameter, due to the large pore sizes or the planar design of the masks. The impact of universal masking in public will be reflected in term of reduce cases.
To combat with COVID-19 in the mid of global shortage of surgical masks, N95 respirators with cost-effective manner recent recommendation by US CDC for healthy people to wear a cloth face cover is appropriate . Study supports the use of cloth masks as a simple, economic and sustainable alternative for life-saving in resource limited settings . Study shows that the cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies .
During the campaign against COVID-19, it is found that the following advanced materials are employed as the structural materials of the protective masks, except for the conventional electrically charged melt blown nonwoven fabric.
This type of mask has been put onto markets since 2016, it is featured with high PFE and relatively low ΔP, and the PFE does not change with time, temperature, or moisture. The pore size is between 100~200nm, and the pores are uniformly distributed across the porous nano-film. It is composed of 5 layers which are outer moisture-proof PP nonwoven layer, two PET structure supporting layers, PTFE filtration core layer, and soft superfine fibrous ES layer (which is skin-friendly and moisture-transferred). The whole mask feels soft and comfortable, but it seems not as so breathable as expected. This mask can be sterilized by heat, Ultrasound, alcohol, or disinfectant, and it can be washed for up to 20 times. However, practically wearing this mask indicated high filtration resistance, not as comfortable as it is claimed.
A Chinese company located in Xiamen, Fujian Province, affiliated to CAS (Chinese Academy of Sciences), has produced masks based on electrospun PVDF based mask, featured with high PFE and low ΔP, and the PFE does not change with time, temperature, or moisture either. These masks have been exported to many countries during COVID-19 outbreak.
Professor Yasuhiro Tsukamoto from the Laboratory of Animal Health, Kyoto Prefectural University, Japan, successfully developed an ostrich antibody with inhibitory response to novel Coronavirus, resulting in a mask having the potential to kill the COVID-19 on the mask via the instant binding of antibodies to the flu virus. Ostrich antibody mask® is a non-woven fabric formed with four layers, including skin-friendly top filter (against face), 3D pleated shape-memory, net-like structural material, electrostatic filter, moisture controlling & water retaining antibody filter layer. The COVID-19 virus will be intercepted by the statically charged layer.
The antibody filtration surface forms a water-retaining layer, which has an amazing number of antibodies that the virus (antigen) can bind to when it gets close enough to cut off the virus. This is called an antigen-antibody reaction, which cuts down the infectious power of COVID-19 when the indispensable spike protein on the surface of the Corona virus is covered by the Ostrich antibody. The strong combination between the spike protein on the COVID-19 surface and the Ostrich antibody may dramatically decrease the infectious risk from the virus.
Test results showed that the Orstrich antibody mask could inhibit the H1N1, H3N2, H5N1, H7N9 at Infection inhibition rates within 10min from 99% to 99.9%. It is claimed that this mask has 99% PFE, BFE and VFE. The test result for COVID-19 is under verification.
Water electret technology was invented in 1994, by which the meltblown material is electrically charged in depth via the friction between pure water and the MB fabric. The pure water jets or stream of pure water drops are used to impact the MB fabric, electric charges will be generated on/in the MB material this way, resulting in high PFE, low ΔP, and durable charging/filtration effect.
After the PET fabric with zinc dots and sliver dots printed on its surface, the redox coupling is formed near the silver and zinc dot, which is also known as network-like weak electric field.
The COVID-19 virus on the PET fabric surface will be killed by the weak electric field of 0.5V, when the virus-carrying apatter is intercepted and captured on the fabric surface, which is indicated by the 0 Zeta potential of the virus particle in the ionic liquid. The weak electric field treated virus shows no effect on the cell activity, indicating the PET fabric killed the corona virus in situ.
In response to the requirements from the customers, Uniqlo, Japan has invented a thin and breathable mask, which is composed of three fabric layers, having 99% filtration efficiency against bacteria, pollen, particulate, virus, etc. The core layer is the thermally calendered 10-15g/m2 meltblown fabric, which is supposed to be the filtration layer, the outer layer is UV resistant net-like knitted fabric, and the inner layer is made from AIRism cloth, the brand fabric of Uniqlo, which is easy to wash and dry, sweat absorbent, cold feeling and breathable.
COVID-19 challenges public health and economy, which also reflected at community and Industry level [1, 6]. Therefore, at first instance control through mask, which can stop human to human transmission is best choice. Finally, adaptations of quality based mask come through startups and companies incorporating innovative materials research information in the development of masks. It is believed that advanced materials science and technology can change the scenario on coming days due to increasing research and innovation in mask developments under pressure of COVID-19 pandemic situation.
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