September 14, 2020

Restoring filtration efficiency after decontamination of used N95 masks

Editor's Note

In this study, researchers from India’s Tata Institute of Fundamental Research and Israel’s Technion-IIT discover how to recharge used N95 masks after decontamination to recover their 95% efficiency. Also included is a proof-of-concept construction of a battery-operated smart mask.

N95 masks are 95% efficient at filtering out 0.3 micron particles, while maintaining reasonable breathability, because of an intermediate layer of charged polypropylene fibers that incorporate electrical charges to attract and trap particles. During use, all electrostatics-based masks slowly lose their efficiency because of humidity.

The researchers propose a method to restore N95 mask filtration efficiency to out-of-box levels. They cleaned used N95 masks in a standard washing machine, which significantly reduced their filtration efficiency, and then recharged them to 95% efficiency by sandwiching them between two electrodes at high voltage.

Their proof-of-concept construction of a battery-operated smart mask involves replenishing a mask’s lost charge periodically by plugging it into a charging station, similar to charging a smartphone.


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