N95 electret charge mask restoration

Mar 22, 2020
I've recently read about that a key property of medical mask filters is the “electret” properties of polypropylene. Apparently polypropylene sheets are charged via corona discharge treatment before manufacture into masks, filters etc.

For most daily use the sheets that comprise the masks retain their charge due to their electret properties but lose this charge when being washed. This is especially the case when alcohol is being used as a disinfectant which is an intuitive go to disinfectant in medical environments.

According to one study I read, this lose of static charge can lead up to 30% reduction in particle capture of the masks for 0.3 micron particles. For smaller particles in the range 0.1 microns (which is the size range of the Corona virus) and smaller the drop was less but still substantial. The interesting point is that these masks haven't mechanically degraded but rather simply have lost there endowed charge and would presumably be "restored" if "recharged".

As I mentioned apparently the charge is given to the material in manufacture by a corona discharge treatment. So this is my question since I am very much a layperson on materiel science, is it possible to simply restore charge to masks , filters etc in a simple manner?

Various scenarios and solutions have come to my mind from simply rubbing the inner lining with relevant material like rabbit fur to impart charge. Another is using the negative output of a Van de Graaff style generator to expose the mask to a negative static field. Another is using a modified negative ion generator (used in air purification) expose the mask to negative charged static charges.

I think this question is important in the extension of n95 and similar filters in hospitals in light of drastically chronic shortage faced in the Corona pandemic.
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