A researcher at the Institute of Industrial Sciences at the University of Tokyo has demonstrated a new method for refilling sterilized N95 masks for reuse. After sterilizing the masks in hot water or autoclave, they were exposed to 100 kilovolts for 3 minutes to restore their static loads. This work can be rapidly applied to help meet the high demand for protective equipment that can prevent the spread of the COVID virus.
During the current COVID pandemic, N95 masks are indispensable for keeping healthcare workers and first responders safe. The name comes from the fact that these masks can filter more than 95% of the particles in the air, despite the fact that the pores are ten times larger than the small aerosol particles that can carry the virus. The trick is that N95 masks are made of electrospun polypropylene fibers that retain static electricity, which can attract and trap charged aerosols. However, this static load cannot withstand normal sterilization procedures such as hot water washing or autoclaving. Moisture in the user’s breath can impair the effectiveness of such an electric attraction. For this reason, masks are often discarded after a single use, which significantly increases the gap between the number of N95 masks needed and those available.
Now, a researcher at the University of Tokyo has shown that sterilized masks can be returned to use after being filled with a van de Graaff generator. These devices, familiar to many visitors to science museums, create very high voltages between two metal conductors using friction in the yarn belt. “Using the high voltage provided by the Van de Graaff generator, this method is faster than alternative methods,” says study author Kaori Sugihara. To restore a previously sterilized mask, a larger metal ball was glued to the ball, and a smaller ball was placed at a distance of a few centimeters for 3 minutes. Updated masks were tested and compared with unused masks in filtering ability.
“I hope this method will give more people access to the N95 masks, our best line of defense against COVID transmission, every day,” Sugihara said. Because the use of Van de Graaff generators is cheaper and safer than other high-voltage sources, this method can be easily applied in hospitals and other places where N95 masks are most needed. The work is published Soft substance such as “Filling N95 masks by van de Graaff generator for safe reuse.”
Reference: December 17, 2020, Soft substance.
DOI: 10.1039 / d0sm02004d