Polyamide Nanofiber-Based Air Filters for Transparent Face Masks

Transparent face masks are the ultimate solution for improving communication during pandemic times while at the same time slowing the spread of pathogens. Here, we demonstrate an easily scalable process consisting of directly electrospinning polyamide nanofibers onto a mechanical stable substrate made of poly(lactic acid) by a needleless setup for the production of transparent filter material. Filtration tests against NaCl and fructose aerosols and pressure drop tests were performed and compared with the European standard for medical face masks (EN 14683:2019) and the Swiss rule for community masks (SNR 30000:2021). The filter showed outstanding transparency (similar to 70% transmittance in the visible-light range), 89% filtration efficiency against PM1.0, and a pressure drop of 6.5 Pa/cm(2).