Metal Tech News - The Elements of Innovation Discovered

Scientists in Italy, United Kingdom, Canada, and now Hong Kong are researching graphene-enhanced masks ability to kill viruses and bacteria, further increasing the face covering's effectiveness in preventing the spread of COVID-19 and other disease.

While face masks made from cloth and other materials provide varying levels of protection against the direct transmission of COVID-19, the virus can live on the surface of most mask materials for up to several days. This poses a risk of secondary transmission from contact with the mask.

"Most of the other masks are currently not able to inactivate the virus but they are able to just decrease the probability of infection by reducing the droplets that are passing through the mask," said Giulio Cesareo, CEO of Directa Plus, an Italy-based company that manufactures virus killing graphene-enhanced COVID-19 face masks.

In addition to rendering the coronavirus strain responsible for COVID-19 inactive, graphene is an effective killer of most other viruses and bacteria.

Looking for an effective defense against the spread of COVID-19, researchers from several universities around the world have come to similar conclusions – graphene-enhanced masks are highly effective at quickly killing of viruses and bacteria.

The latest research comes from a team at the City University of Hong Kong, which has successfully produced graphene masks with an anti-bacterial efficiency of 80%, which can be enhanced to almost 100% with exposure to sunlight for around 10 minutes.

Led by Dr. Ye Ruquan, assistant professor at CityU's department of chemistry, this team has developed masks that are easily produced at low costs due to the ease of manufacturing the graphene material used.

While earning his doctorate at Rice University, the research team Ye was on found that using lasers to write on carbon-containing polyimide films – a plastic material with high thermal stability – can create 3D porous graphene.

While polyimide film is the material of choice for the mask, lasers can make graphene on just about anything that contains carbon. Previous testing has used lasers to create graphene on the surface of paper, cloth, coconuts, potatoes, and even a slice of bread.

Prior to the COVID-19 pandemic, Ye was studying the use of laser-induced graphene in the development of sustainable energy technologies.

Knowing graphene's ability to neutralize bacteria and viruses, Ye spearheaded a study into efficiently producing laser-induced graphene face masks.

Testing by the CityU research team found their laser-induced graphene quickly killed about 82% of the bacteria E. coli. More than 90% of the E. coli bacteria deposited on carbon-fiber and melt-blown fabrics – nonwoven materials commonly used to make disposable face masks – remained alive after eight hours.

Previous studies suggested that COVID-19 would lose its infectivity at high temperatures. So, the team carried out experiments to test if the graphene's antibacterial would be enhanced when exposed to rays from the sun.

The results showed that the anti-bacterial efficiency of the graphene material could be improved to 99.998% within 10 minutes under sunlight, while carbon-fiber and melt-blown fabrics only showed an efficiency of 67% and 85% respectively.

The Hong Kong team is currently working with laboratories in mainland China to test the graphene material with two species of coronavirus. Initial tests show that it inactivated over 90% of the viruses in five minutes and almost 100% in 10 minutes under sunlight. The team also plans to conduct testing with the COVID-19 virus.

Dr. Ye said that more research on the exact mechanism of graphene's bacteria-killing property is needed. But he believes it is related to the damage of bacterial cell membranes by graphene's sharp edges.

City University of Hong Kong

CityU research team members: (front row from the left) Xu Siyu Dr. Ye Ruquan, and Huang Libei; (back row from the left) Cao Xiaohu, Song Yun, and Su Jianjun.

This is in line with other research that shows graphene, being only one atom thick, has sharp edges that cut into the membranes of bacteria and viruses. Research also indicates that the 2D material causes oxidative stress to microorganisms, which is similar to the microbe killing function of hydrogen peroxide.

Graphene's highly conductive properties may also play a role in its strong antimicrobial properties.

The next step for the CityU research team is to further enhance the antivirus efficiency of and develop a reusable strategy for the laser-induced graphene masks.

Dr. Ye says producing the laser-induced graphene is easy, quick, and affordable. A single laser can convert carbon in polyimide film sheets in about 1.5 minutes and the breathability of the masks can be modified simply by changing the laser power.

The CityU team plans to release their graphene mask to the market shortly after designing an optimal structure for the mask and obtaining the required certifications.