Promises anti-bacterial efficiency close to 100% and neutralizing coronavirus under 10 minutes of sunlight.
Face masks have become an important tool in fighting masks COVID-19 Ubiquitous epidemic. However, improper use or disposal of masks can lead to “secondary transmission”. A research team from City University of Hong Kong (CityU) has successfully produced Graphene Mask with an anti-bacterial efficiency of 80%, which can be increased to about 100% by exposure to sunlight for about 10 minutes. Initial tests also showed very promising results in the inactivation of two species of coronavir. Graphene masks are easily produced at low cost, and can help solve the problems of raw material sourcing and disposal of non-biodegradable masks.
Research In collaboration with other researchers, Assistant Professor of the Department of Chemistry of CityU, Dr. U is held by Rukwan. The findings were published in the scientific journal ACS Nano, entitled “Self-Reporting and Photography-Enhanced Rapid Bacterial Killing A Laser-Induced Graphene Mask.”
Commonly used surgical masks are not anti-bacterial. This can lead to the risk of secondary transmission of bacterial infection when people touch the contaminated surfaces of masks used or discard improperly. In addition, the melt-blown clothes used as a bacterial filter have an impact on the environment because they are difficult to rot. Therefore, scientists are looking for alternative materials to make masks.
Laser converting other materials to graphene
Dr. Y is studying the use of laser-induced graphene in developing sustainable energy. When he was studying a PhD degree at Rice University several years ago, he participated in the research team led by his supervisor and discovered an easy way to produce graphene. They found that using a commercial CO2 infrared laser system, direct writing on carbon-containing polyimide films (a polymer plastic material with high thermal stability) can produce 3D porous graphene. The laser changes the composition of the raw material and therefore produces graphene. That is why it is named laser-inspired graphene.
Graphene is known for its anti-bacterial properties, so at the beginning of last September, before the outbreak of COVID-19, production of outperforming masks with laser-induced graphene was already underway. It came to his mind. He then began the study with researchers from Hong Kong University of Science and Technology (HKUST), Nankai University and other organizations.
Excellent anti-bacterial efficiency
The research team e. Tested its laser-induced graphene with coli, and it achieved a high anti-bacterial efficiency of about 82%. In comparison, the anti-bacterial efficiency of commonly used materials in both activated carbon fiber and melt-blown fabrics was 2% and 9%, respectively. The results of the experiment also showed that deposits on them e. More than 90% of the coli survived even after 8 hours, while most E. coli deposited on the surface of graphene were dead after 8 hours. Furthermore, laser-induced graphene had an improved anti-bacterial capacity for aerosolized bacteria.
Dr. Yeh stated that more research is needed on the precise mechanism of graphene killing bacteria. But he believed that it could be related to the loss of bacterial cell membrane by the sharp edge of graphene. And bacteria can be killed by dehydration induced by the hydrophobic (water-repellent) property of graphene.
Previous studies suggested that COVID-19 would lose its infectivity at high temperatures. The team therefore carried out experiments to test if the photothermal effect of graphene (generating heat after absorbing light) could enhance the anti-bacterial effect. The results showed that the anti-bacterial efficiency of the graphene content could be improved to 99.998% within 10 minutes under sunlight, while activated carbon fiber and melt-blown fabrics showed efficiency of 67% and 85%, respectively. .
The team is currently working with laboratories in mainland China to test graphene content with two species of human coronaviruses. Initial tests showed that it became inactive in 90% of viruses in five minutes and in sunlight in about 100% of 10 minutes. The team plans to test it later with the COVID-19 virus.
Their next step is to increase anti-virus efficiency and develop a reusable strategy for masks. They hope to design an optimal structure for the mask and release it to the market soon after obtaining the certificate.
Dr. Yeh called the production of laser-inspired graphene a “green technology”. All carbon-containing materials, such as cellulose or paper, can be converted to graphene using this technique. And the conversion can be done in ambient conditions without using chemicals other than raw materials, nor cause pollution. And energy consumption is less.
Laser-inspired graphene masks are reusable. If biometric is used to produce graphene, sourcing raw materials for masks can help solve the problem. And it can reduce the environmental impact caused by non-biodegradable disposable masks, ”he said.
Dr. Yeh pointed out that laser-induced graphene production is easy. Within just one and a half minutes, an area of 100cm be can be converted to graphene as the outer or inner layer of the mask. Based on the raw material for the production of graphene, the laser-induced graphene mask is expected to be priced between the surgical mask and the N95 mask. He stated that by adjusting the laser power, the shape of the pores of the graphene material could be modified, so that the trachea was similar to a surgical mask.
A new way to check the status of a mask
To allow users to test whether graphene masks are still in good condition after being used for a time, the team designed a hygroelectric generator. It is powered by moisture generated by human breath. By measuring the change in moisture-induced voltage when the user breathes through a graphene mask, it provides an indicator of the condition of the mask. Experiment results have shown that the more bacteria and atmospheric particles accumulate on the surface of the mask, the lower the voltage. “The standard of how often a mask should be changed is better decided by professionals. Nevertheless, we can use this method as a reference, ”Dr. Suggested this.
References: “Self-Reporting and Rapid Bacterial Killing on a Laser-Induced Graphene Mask” by Libya Huang, Siu Xu, Zhaoyu Wang, Ke X, Jianjun Su, Yun Song, Sijie Chen, Chunli Zhu, Ben Zhong Tang and Rukwanan. This, 11 August 2020, ACS Nano.
DOI: 10.1021 / acsnano.0c05330
Dr. Y is one of the paper’s respective authors. The other two compatible authors are Professor Tang Benzong from HUSET and Dr. from Nankai University. Zhu Chunli The first author of the paper, Drs. This is PhD student Huang Liibei. Other CityU team members are Xu Siu, Su Jianjun and Song Yu from the chemistry department. Other collaborators included HKUSE, researchers at Nankai University, as well as Dr. of the Ming Wai Lau Center for Reproductive Medicine, Karolinska Institute. Chain sizzi included.
The study was supported by CityU and Nankai University.