COVID-19 Face Mask Containing Laser-Induced Graphene Deactivates Coronavirus Under Sunlight

However, graphene is known for its anti-bacterial properties which have attracted scientists towards the possibility of making graphene masks. Conventional methods for producing graphene include chemical vapor deposition in which graphene is first grown on a porous substrate at high temperatures and the substrate is subsequently etched; and the hydrothermal method in which graphene oxide collects together and is simultaneously reduced in hot water. However, these two methods have poor control over the shape of the product and require high-temperature conditions, lengthy synthesis routes, and high costs.

In their previous studies, the team of scientists had discovered that direct writing on commercial polyimide films (a polymeric plastic material) or other biomaterials using a commercial CO2 infrared laser system can generate 3D porous graphene, thus making the fabrication of graphene masks quick and easy. Their breakthrough method combines graphene preparation and patterning into a single step. Under computer control, the laser-induced graphene (LIG) can be patterned into various shapes with a porous structure. The masks are made comfortable for breathing by adjusting the laser power to modify the size of the pores. The method is time and cost effective and may help to resolve the problem of sourcing raw materials. Most carbon containing materials, for example cellulose or paper, can be converted into graphene. In addition, the conversion can be carried out under ambient conditions with a laser system found in most machine shops.

Preliminary studies on the anti-bacterial graphene masks are already underway. The LIG material developed by the scientists can kill almost all the E. coli and aerosolized bacteria with the bacteria-killing activity being induced by the graphene-bacteria interactions. Under the photothermal effect of the sun, the scientists found that it was possible to kill bacteria with an efficiency of 99.998% within 10 minutes. In addition, the team has recently begun testing LIG material's ability to combat viruses and has achieved very promising results. Initial tests on two coronaviruses found that the LIG material inactivated over 90% of the virus in five minutes and all of them in 10 minutes. The LIG material has a range of other applications such as fabricating antibacterial medical devices.

The team has also fabricated a hygroelectric generator powered by human breath that can self-report on the condition of a mask. The adhesion of bacteria or atmospheric particles on the LIG changes surface properties and affects moisture-induced potential, which provides information on the condition of a mask. This kind of mask improves the protection effect, which is especially important for frontline workers.

“I think production streamlining should be simple and the price is expected to fall in between that of a surgical mask and a N95 mask,” said Dr. Ye Ruquan, Assistant Professor in the Department of Chemistry at City University of Hong Kong, who discovered the new method for making anti-bacterial graphene masks. “Our next plan is to evaluate the antivirus efficiency and develop a reusable strategy. We have made a face mask prototype, and with an optimal structure, we envision releasing it to the market shortly after obtaining the certified tests.”

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City University of Hong Kong