Electrocharging face masks with corona discharge treatment

We detail an experimental method to electrocharge N95 facepiece respirators and face masks (FMs) made from a variety of fabrics (including non-woven polymer and knitted cloth) using corona discharge treatment (CDT). We present practical designs to construct a CDT system from commonly available parts and detail calibrations performed on different fabrics to study their electrocharging characteristics. After confirming the post-CDT structural integrity of fabrics, measurements showed that all non-woven polymer electret and only some knitted cloth fabrics are capable of charge retention. Whereas polymeric fabrics follow the well-known isothermal charging route, ion adsorption causes electrocharging in knitted cloth fabrics. Filtration tests demonstrate improved steady filtration efficiency in non-woven polymer electret filters. On the other hand, knitted cloth fabric filters capable of charge retention start with improved filtration efficiency which decays in time over up to 7 h depending on the fabric type, with filtration efficiency tracking the electric discharge. A rapid recharge for a few seconds ensures FM reuse over multiple cycles without degradation.

Methods
The data was collected using a variety of unrelated methods.

Structural Integrity data include:

1) Scanning electron micrographs for surgical masks pre and post-corona discharge treatment (CDT) in the form of high resolution TIFF images collected using Scanning Electron Microscopy.

2) Video movie files showing CDT of face masks at different distances between fabric sample and discharge, Infrared imaging of surgical masks undergoing CDT, sample video movies of bare electrodes with corona discharge at 30 frames per second and slow motion, 240 frames per second, and finally a video exhibiting the linear guide rail apparatus for raster scan method for CDT of fabric samples.

3) Text data include: charge measurements and filtration efficiency measurements for various fabric samples over a 12 hour duration.