Moisture-resistant, sterilizable and reusable N-95 like piezoelectric facemask filtering membrane with long-term biodegradability

Abstract Facemasks have been shown to be the most effective tool to prevent the spreading and transmission of infectious viruses in pandemics. Many countries, including the US, have enforced the use of facemasks in public area or healthcare settings to protect healthcare workers and general population against highly contagious viral strains of the SARS-COVID-2. This global enforcement of facemasks has led to billions of N95/surgical masks (which are intended for single-use and are non-degradable) being disposed of in landfills and ocean, causing a significant crisis on the environment. Aside from viral infection, particulate matters (PMs, i.e. small particles with sizes at nano or micro-meters) from the combustion of fossil fuels around the world also has severe impact on human health. Especially, small particles such as PM1.0 or PM2.5 (i.e. sizes < 1 µm and 2.5 µm, respectively) are the most poisonous and harmful ones since they can travel into deeper parts of the respiratory tract and even penetrate into the bloodstream. In this regard, facemasks have also been the most effective solution to protect public health from industrial PMs and air pollution. Given such a tremendous demand of filtration facemask membranes, the heavy and continuous use of traditional non-degradable, one-time disposable facemasks (e.g. N95 and surgical masks) will not only be an economic burden but also cause an environmental crisis with billions of permanent plastic wastes disposed every year. Besides the environmental problem, current facemasks struggle with a significant drawback of losing filtration function after a long period of continuous use and exposure of humid air, thus making the mask users non-protective against the risk of viral infection. Herein, we propose a novel piezoelectric composite nanofiber mesh of Poly-L-Lactide (PLLA) and Magnesium Oxide (MgO) which provides all properties of an ideal filtering membrane, including (1) moisture- resistance, (2) good mechanical strength, (3) N95-like filtering efficiency, (4) small pressure-drop, (5) reusability/sterilize-ability, and (6) long-term biodegradation to avoid any harm on the environment. Our major hypothesis is that by creating a highly piezoelectric MgO/PLLA and then employ multi-layer of the MgO/PLLA nanofiber mesh with tunable pore size/pore number in each layer, we will be able to produce a desired filter with a high filtration efficiency and low pressure drop, similar to a N95 facemask filter. To achieve the facemask and demonstrate the hypothesis in this phase I SBIR, we design the project with two aims. Aims 1 (6 months) is to characterize the MgO/PLLA nanofiber membrane filter in terms of piezoelectric effect, mechanical property, and porosity of the nanofiber membrane. Aim 2 (12 months) is to fabricate the multi-layer filtering membrane with the MgO/PLLA nanofiber mesh patterned with micro-pores and achieve the N-95 performance in terms of filtering efficiency and pressure drop.