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Electrocharging face masks with corona discharge treatment

Citation

Bandi, Mahesh et al. (2021), Electrocharging face masks with corona discharge treatment, Dryad, Dataset, https://doi.org/10.5061/dryad.95x69p8js

Abstract

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.

Usage Notes

We do not anticipate anyone requiring specialized resources to use these datasets:

1) Standard image visualization software such as Adobe Photoshop or open-source GIMP software suffice for visualization of TIFF image files.

2) All videos are made available in .MOV format and can be played on standard video players such as Apple quicktime.

3) Text data for charge and filtration measurements can be used with any standard graphing tool such as Origin, Matlab, Sigmaplot, Igor etc.

Structure of the data set. All data files are presented in a single folder

Image Files:

SMask-PreCDT.tif: This file presents scanning electron micrograph for surgical mask pre-CDT.

SMask-PostCDT.tif: This file presents scanning electron micrograph for surgical mask post-CDT.

Together these two files are presented in figure 7 a and b respectively in the manuscript.

 

Data Files: 

Cotton-PostCDT-FTIR.txt: Contains FTIR results for post-CDT cotton fabric samples at 3 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

Cotton-PreCDT-FTIR.txt: Contains FTIR results for pre-CDT cotton fabric samples at 3 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

These two files together are presented in figure 10 of the main mansucript.

Polyester-PostCDT-FTIR.txt: Contains FTIR results for post-CDT polyester fabric samples at 5 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

Polyester-PreCDT-FTIR.txt: Contains FTIR results for pre-CDT cotton fabric samples at 5 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

These two files together are presented in figure 11a of the main mansucript.

Silk-PostCDT-FTIR.txt: Contains FTIR results for post-CDT silk fabric samples at 5 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

Silk-PreCDT-FTIR.txt: Contains FTIR results for pre-CDT silk fabric samples at 5 cm vertical distance between sample and corona discharge. File structure is tab-limited text with two columns. Column 1 lists wavenumber (1/cm) and column 2 lists FTIR absorbance in ATR units.

These two files together are presented in figure 11b of the main mansucript.

ElectretFabrics-Charge.txt: This file lists charge measurements performed on various electret, polymeric electrocharged filtration facepiece respirators, face masks, and fabrics. File structure is tab limited: Column 1 lists time (in hours) in 1 hour steps for 12 hour duration, Column 2 charge (in nano coulombs nC) for new N95 facepiece respirator, Column 3 charge for used and recharged (using CDT) N95 facepiece respirator, Column 4 charge for surgical mask post-CDT, Column 5 charge for polypropylene and Column 6 charge for Polystyrene fabrics manufactured in-house using the cotton candy method. This data is presented in figure 13 of the manuscript.

KnittedFabrics-Charge.txt: This file lists charge measurements performed on various knitted cloth fabrics post-CDT. File structure is tab limited: column 1 lists time (in hours) in 1 hour steps for 12 hour duration, Column 2 charge (in nano coulombs nC) for polyester, Column 3 charge for Cellulose, Column 4 charge for Nylon, Column 5 charge for Polyethyelene Terephthalate (PET), and Column 6 charge for Polyphenylene Sulfide (PPS). This data is presented in figure 14 of the manuscript.

N95-SM-Penetration.txt: This file lists filtration efficiency test measurements performed on N95 facepiece respirators and surgical masks. File structure is tab limited: column 1 lists time (in hours) in 15 minute steps for 12 hour duration, Column 2 penetration (%) for new N95 facepiece respirator, column 3 penetration for used and recharged (using CDT) N95 facepiece respirator, column 4 for a pre-CDT surgical mask and column 5 for post-CDT surgical mask. This data is presented in figure 15 of the manuscript.

KnittedCloth-Penetration.txt: This file lists filtration efficiency test measurements performed on knitted cloth fabrics. File structure is tab limited: column 1 lists time (in hours) in 15 minute steps for 12 hour duration, column 2 penetration (%) for Cellulose (pre-CDT), column 3 penetration for cellulose (post-CDT), column 5 penetration for polyester (pre-CDT), column 6 penetration for polyester (post-CDT), column 7 penetration for Nylon (pre-CDT), column 8 penetration for Nylon (post-CDT), column 9 penetration for PET (pre-CDT), column 10 penetration for PET (post-CDT), column 11 penetration for PPS (pre-CDT) and column 12 penetration for PPS (post-CDT).

 

Video Files:

CMask-CDTburn.MOV: This file shows singeing (observed as yellow flashes) of threads in a cotton face mask when the corona discharge (blue glow) is in contact with fabric.

M1.mov: Corona discharge, transverse electric wind observed as blue glow, and discharge sparks observed from bare electrodes at 30 frames per second.

M2.mov: Corona discharge, transverse electric wind observed as blue glow, and discharge sparks together with trichel pulses heard as semi-periodic clicks from bare electrodes at 240 frames per second.

M3.mov: The electrode system mounted on a linear guide rail that achieves raster scan of CDT on fabric samples.

SMask-7cm-CDT.MOV: Surgical mask undergoing CDT at a 7 cm vertical gap between mask and discharge.

SMask-3cm-CDT.MOV: Surgical mask undergoing CDT at a 3 cm vertical gap between mask and discharge.

SMIR-3cm.MOV: Infrared thermal imaging video for surgical mask undergoing CDT at a 3 cm vertical gap between mask and discharge.

SMIR-7cm.MOV: Infrared thermal imaging video for surgical mask undergoing CDT at a 7 cm vertical gap between mask and discharge.

Funding

Nonlinear and Non-equilibrium Physics Unit, OIST Graduate University