Effect of Ultraviolet C Disinfection Treatment on the Nanomechanical and Topographic Properties of N95 Respirator Filtration Microfibers

Meng Yujie,Zeng Rae,Rubin Kurt,Barry Kelly

doi:10.1557/adv.2020.347

Abstract

Ultraviolet germicidal irradiation (UVGI) N95 filtering facepiece respirator (FFR) treatment is considered an effective decontamination approach to address the supply shortage of N95 FFRs during the ongoing Covid-19 pandemic. In this study, we investigated the nanomechanical and topographic properties of filtration fibers that have been exposed to different doses of UVC radiation. UVC exposure was shown to decrease both Young’s modulus (E), hardness (H) and fiber width, as measured on individual polypropylene (PP) fibers. Our results also show that the PP microfiber layer loses its strength when N95 respirators are exposed to an accumulated UVC dose during the process of decontamination, and the PP fiber width also exhibits a logarithmic decrease during UVC exposure. The nanoscale measurement results on individual fibers suggest that maximum cycles of UVC disinfection treatment should be limited due to excessive accumulated dose, which has the potential to decrease the fiber breaking strength.

Highlights

The unprecedented Covid-19 epidemic has led to a critical shortage of personal protective equipment (PPE)
The N95 filtering facepiece respirator (FFR) face mask is typically composed of multiple filtration layers, including those shown in Figure 1a, with the inner filtration layer considered to be the key functional component [1]
The N95 respirator meltblown layer microfibers were prepared under the following protocol: (1) the PP microfibers were untangled and placed on painter’s tape, pushed down firmly to make good adhesive contact with the tape; (2) a thin layer of epoxy was applied to the aluminum sample stub; (3) the microfibers were placed on the epoxy and pushed firmly to make solid contact with the aluminum stub; and (4) the tape was removed after the epoxy cured

Summary

Introduction

The unprecedented Covid-19 epidemic has led to a critical shortage of personal protective equipment (PPE). N95 masks are one of the key PPEs to protect frontline healthcare workers, and these devices are intended to be used once and disposed. The N95 filtering facepiece respirator (FFR) face mask is typically composed of multiple filtration layers, including those shown, with the inner filtration layer considered to be the key functional component [1]. This layer is made from meltblown non-woven fabric, which is composed of thousands of very thin, noncontinuous fibrils. An electric charge on the fibers enables a 10 times higher filtration efficiency without adversely increasing the air resistance, due to a technique called corona electrostatic charging applied to the N95 filtration layer during manufacturing [2].

Methods

Results

Conclusion