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Since the COVID-19 pandemic outbreaks, the utilization of medical masks plays a critical role in reducing the infected risk. However, constructing multifunctional masks to achieve simultaneously self-sterilization, reusability, and respiratory monitoring capability remains still a huge challenge. Herein, a reusable Ag micro-mesh film-based mask is proposed, which enables the capabilities of electrothermal sterilization and self-powered real-time respiratory monitoring. Highly conductive Ag micro-mesh films prepared by continuous draw spinning method demonstrate excellent electrothermal performances for thermal sterilization and serve as working electrode to fabricate triboelectric nanogenerator (TENG) for real-time respiratory monitoring, respectively. Under a low driving voltage of 3.0 V, the surface temperature of Ag micro-mesh film enables a quick increase to over 60 °C within 30 s, which endows thermal sterilization against S. aureus with antibacterial efficiency of 95.58 % within 20 min to achieve the self-sterilization of medical masks. Furthermore, a self-powered alarm system based on the fabricated TENG as respiratory monitor is developed for real-time respiratory monitoring to render a timely treatment for patients in danger of tachypnea and apnea. Consequently, this work has paved a new and practical avenue to achieve reusable multifunctional masks with capabilities of electrothermal sterilization and real-time respiratory monitoring in clinical medicine.

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Discontinuous dewetting is an attractive technique that can produce droplet array of specific volume, geometry and at predefined location on a substrate. Droplet array has great potential in bioanalysis such as high-throughput live cell screening, digital PCR, and drug candidates. Here, we propose a self-dispersing droplet array generation method, which has advantages of low cost, simple operation, and easy large-area production ability. Droplet array of specific volumes was generated on a polymethyl methacrylate (PMMA) substrate using a simple reusable polyimide (PI) adhesive mask. Experiment shows that the generated droplet array can be used to successfully capture single particles which obeys Poisson distribution in a high-throughput manner. Furthermore, a droplet-array sandwiching chip was created based on the self-dispersion method for rapid detection of human serum albumin (HSA) at wide range of 183-11,712 µg/mL with low reagent consumption of 2.2 µL, demonstrating its potential applications in convenient high-throughput bioanalysis and bioassays.

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The worldwide spread of coronavirus COVID-19 infections demonstrates the great need for personal protective equipment and, in particular, hygiene masks. These masks are essential for the primary protection of the respiratory tract against pathogens such as viruses and bacteria that are infectious and transmitted through the air as large droplets or via small airborne particles. The use of protective masks will continue to accompany humans for an indefinite period of time, and therefore there is an urgent need for a safe method to extend their usability by reusing them under perspective with minimal loss of protective properties. Nanofiber mats are widely used in masks and in this study the reusability of nanofiber mats is investigated by washing them at different temperatures. This paper shows the first measurements of the washability of nanofiber mats. Furthermore, the air permeability is measured, and the evaporation resistance is evaluated. According to the results of this study, the air permeability performance of nanofiber mats does not change significantly after washing, confirming the possibility of reuse.

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The outbreak of Coronavirus Disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered great global public health concern. Face masks are essential tools to reduce the spread of SARS-CoV-2 from human to human. However, there are still challenges to prolong the serving life and maintain the filtering performance of the current commercial mask. Filters composed of ultrafine fibers with diameter down to tens of nanometers have the potential to physically block viruses. With adjustable composition and nanostructures, the electrospun ultrafine fiber filter is possible to achieve other necessary functions beyond virus blocking, such as antiviral, transparent, and degradable, making it an important part of fighting the epidemic. In this review, beginning with the basic information of the viruses, we summarize the knowledge of masks and respirators, including the filtering mechanism, structure, classification, and standards. We further present the fabrication method, filtering performance, and reusable potential of electrospun ultrafine fiber-based masks. In the end, we discuss the development directions of ultrafine fibers in protective devices, especially their new functional applications and possible contributions in the prevention and control of the epidemic.

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The coronavirus disease 2019 (COVID-19) pandemic has led to a great demand on the personal protection products such as reusable masks. As a key raw material for masks, meltblown fabrics play an important role in rejection of aerosols. However, the electrostatic dominated aerosol rejection mechanism of meltblown fabrics prevents the mask from maintaining the desired protective effect after the static charge degradation. Herein, novel reusable masks with high aerosols rejection efficiency were fabricated by the introduction of spider-web bionic nanofiber membrane (nano cobweb-biomimetic membrane). The reuse stability of meltblown and nanofiber membrane mask was separately evaluated by infiltrating water, 75% alcohol solution, and exposing under ultraviolet (UV) light. After the water immersion test, the filtration efficiency of meltblown mask was decreased to about 79%, while the nanofiber membrane was maintained at 99%. The same phenomenon could be observed after the 75% alcohol treatment, a high filtration efficiency of 99% was maintained in nanofiber membrane, but obvious negative effect was observed in meltblown mask, which decreased to about 50%. In addition, after long-term expose under UV light, no filtration efficiency decrease was observed in nanofiber membrane, which provide a suitable way to disinfect the potential carried virus. This work successfully achieved the daily disinfection and reuse of masks, which effectively alleviate the shortage of masks during this special period.

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The coronavirus outbreak that commenced at the end of 2019 has led to a dramatic increase in the demand for face masks. In countries that are experiencing a shortage of face masks as a result of panic buying or inadequate supply, reusable fabric masks have become a popular option, because they are often considered more cost-effective and environmentally friendly than disposable medical masks. Nevertheless, there remains a significant variation in the quality and performance of existing face masks; not all are simultaneously able to provide protection against the extremely contagious virus and be comfortable to wear. This study aims to examine the influential factors that affect the comfort of reusable face masks, but not to assess the antimicrobial or antiviral potential. Seven types of masks were selected in this study and subjected to air and water vapor permeability testing, thermal conductivity testing and a wear trial. The results indicate that washable face masks made of thin layers of knitted fabric with low density and a permeable filter are more breathable. Additionally, masks that contain sufficient highly thermally conductive materials and have good water vapor permeability are often more comfortable to wear as they can transfer heat and moisture from the body quickly, and thus do not easily dampen and deteriorate.

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Since the outbreak of the severe respiratory disease caused by the novel coronavirus (COVID-19), the use of face masks has become ubiquitous worldwide to control the rapid spread of this pandemic. As a result, the world is currently facing a face mask shortage, and some countries have placed limits on the number of masks that can be bought by each person. Although the surgical grade N95 mask provides the highest level of protection currently available, its filtration efficiency for sub-300 nm particles is around 85% due to its wider pore size (∼300 nm). Because the COVID-19 virus shows a diameter of around 65-125 nm, there is a need for developing more efficient masks. To overcome these issues, we demonstrate the development of a flexible, nanoporous membrane to achieve a reusable N95 mask with a replaceable membrane and enhanced filtration efficiency. We first developed a flexible nanoporous Si-based template on a silicon-on-insulator wafer using KOH etching and then used the template as a hard mask during a reactive ion etching process to transfer the patterns onto a flexible and lightweight (<0.12 g) polymeric membrane. Pores with sizes down to 5 nm were achieved with a narrow distribution. Theoretical calculations show that airflow rates above 85 L/min are possible through the mask, which confirms its breathability over a wide range of pore sizes, densities, membrane thicknesses, and pressure drops. Finally, the membrane is intrinsically hydrophobic, which contributes to antifouling and self-cleaning as a result of droplets rolling and sliding on the inclined mask area.

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