It’s one of the biggest debates that will refuse to die down even after the covid-19 pandemic subsides. How effective is a face mask? More importantly, what is the right type of mask an average user should wear to protect themselves from the novel coronavirus? An N95, a cloth mask or a surgical mask?
The answer to these questions has led to some of the most innovative mask designs that have either been implemented or are still in the various stages of development: masks with nano-tech filters, see-through masks that are also reusable or masks that use interchangeable carbon activated filters. The list is endless.
Now, engineers at the Massachusetts Institute of Technology (MIT) are hoping to create a mask that inactivates viruses using heat. It is a well-known fact that heating can kill or inactivate disease-causing pathogens. But how does one design a heated mask that also causes no degree of discomfort to the wearer?
The researchers at MIT are following a completely new concept of a face mask that users a heated copper mesh that would inactivate viruses, rather than filtering them. “As the person wearing the mask breathes in and out, air flows repeatedly across the mesh, and any viral particles in the air are slowed and inactivated by the mesh and high temperatures,” according to an official news release on the research, which adds that the researchers have already started designing prototypes and hope to test them soon.
This new design concept was described recently in a paper on bioRxiv, an open access preprint repository for the biological sciences. The paper has also been submitted to a peer-reviewed journal and filed a patent for the mask design. “The masks that we wear now are designed to capture some of the virus. They do offer protection, but there's no one really thinking about inactivating the virus and sterilizing the air. That surprised me,” Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and senior author of the paper, said in the release.
Other authors include MIT graduate students Samuel Faucher, Daniel Lundberg, Xinyao Liang, and Xiaojia Jin; undergraduate Rosalie Phillips; postdoc Dorsa Parviz; and Jacopo Buongiorno, the TEPCO Professor of Nuclear Science and Engineering at MIT.
Strano and other members working on this concept went through existing scientific reports on the different types of masks but did not find any that were designed “primarily to kill viruses by heating”. The copper mesh they hope to use in their design will not only acting as the heating component but also the capturing element. Using mathematical models, the team calculated the optimal temperature range that would be needed to kill coronaviruses flowing inward or outward from natural breathing, the release explains.
A temperature of about 90 degrees Celsius “could achieve between a thousandfold and millionfold reduction in viral particles, depending on the final mask size.” This kind of temperature in the mask could be achieved by running an electrical current across a 0.1-millimeter thick copper mesh or thermoelectric heater, which would be powered by a small battery. "The current prototypes include a 9-volt battery, which would provide enough power to heat the mask for a few hours and would cool the air before it is inhaled,” the release adds.
Interestingly, the researchers explain, the mask’s ability to deactivate the virus could be enhanced by leveraging a concept know as a “reverse-flow reactor”. As a person wearing the mask breathes in and out, the air flow continually reverses. This would allow any viruses in the mask to pass over the mesh multiple times, making it more likely that they will be deactivated by the heat. Purified air would then flow out of vents on both sides of the mask. The copper mesh would be surrounded by neoprene, an insulating material, that would prevents the outside of the mask from becoming too hot to wear, the release adds.
While any such heated masks would be more expensive than the conventional ones, a possible advantage would be the fact that heated masks would not have to be decontaminated or thrown away since they would not only filter the virus, but also kill it.