The reusable mask would include a heated copper mesh that's powered by a battery and surrounded by insulating neoprene. As the wearer of 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.
Such a mask, say the researchers, could be useful for health care professionals, as well as members of the public in situations where social distancing would be difficult to achieve, such as a crowded bus.
"This is a completely new mask concept in that it doesn't primarily block the virus," says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. "It actually lets the virus go through the mask, but slows and inactivates it."
“The masks that we wear now are designed to capture some of the virus," says Strano. "They do offer protection, but there's no one really thinking about inactivating the virus and sterilizing the air."
In setting out to design a mask that would kill viruses using heat, the researchers decided to use copper mesh as the heating and capture element, and performed some mathematical modeling to determine the optimal temperature range they would need to achieve to kill coronaviruses flowing inward or outward from natural breathing.
"The vast majority of masks today function by filtration, filtering particles by size or electric charge," says MIT graduate student Samuel Faucher. "This mask relies on a different mechanism and works predominantly by thermal inactivation."
The researchers calculated how rapidly coronaviruses degrade at different temperatures and trapping conditions, and found that a temperature of about 90°C (194°F) could achieve between a thousandfold and millionfold reduction in viral particles, depending on the final mask size. Further, they showed that that temperature can be achieved by running an electrical current across a 0.1-millimeter-thick copper mesh or thermoelectric heater, powered by a small battery.
The current prototypes include