As governments and organizations attempt to develop a vaccine for COVID-19, the N95 respirator continues to serve as an invaluable component of the personal protective equipment (PPE) against further SARS-CoV-2 infections.
Crucial to the safety of health workers, the specialized masks are currently in shortage in hospitals and medical facilities across the U.S., leading some to question whether they can be sterilized and reused.
Earlier this month, a Taiwanese man came forward to answer questions about sterilizing and reusing N95 respirators, 30 years after he invented the key technology behind them.
He is Peter Tsai, a materials scientist and engineer known for his work in nonwoven fabrics.
For the record, Tsai did not create the N95, but he invented the electrostatic charging technology that is used to produce its filter media, according to the Taipei Times.
The “N” in N95 stands for “not resistant to oil,” while the “95” denotes the ability to remove at least 95% of submicron particles, including dust, haze, pollen, smoke and influenza viruses.
N95 respirators are made of four plies of polypropylene media: (1) an outer veil that is moisture resistant, (2,3) a double-ply filtration layer, and (4) an inner layer that is in contact with the skin.
The efficiency of the respirator lies in the middle filtration layer, which is developed through the processes of “melt blowing and electrostatic charging.”
Born in central Taiwan, Tsai studied chemical fiber engineering at the Provincial Taipei Institute of Technology (now Taipei Tech) and graduated in 1975 — a Golden Age of the Taiwanese textile industry. He immediately landed his first job at the China Testing and Research Center (now the Taiwan Textile Research Institute).
While working, Tsai eventually realized that Taiwan had only been importing equipment and technology from other countries to run its textile industry. This led him to a decision to come to the U.S. and “figure things out,” according to the CommonWealth Magazine.
Tsai enrolled in Kansas State University, studying courses from multiple disciplines such as mechanical engineering, electrical engineering, chemical engineering, physics and mathematics. While other Ph.D. students needed 90 credits to graduate, he had a whopping 500.
Through his research supervisor, Tsai was eventually introduced to “melt blowing.” In essence, it is a production process that turns fibers into nonwoven fabrics with extremely fine pores.
Electrostatic charging, on the other hand, imbues the fiber with an electric charge. This results in an electret, a material capable of absorbing and capturing microorganisms such as bacteria and viruses.
Drawing knowledge from the various disciplines he has dabbled in, Tsai solved the problems of producing nonwoven fabric (through melt blowing) and improving filtration (through electrostatic charging). He helped a research team at the University of Tennessee develop the technology.
Tsai, who owns 12 patents, retired from the University of Tennessee last year. But he continues to study ways of improving the N95 so that it can be reused.
“The front-line hospital workers — they are heroes. I’m just trying to help them to wear the mask,” he told NPR’s Morning Edition.