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

摘要 口罩已被证明是防止传染病传播和传播的最有效工具。 流行病中的病毒包括美国在内的许多国家都强制在公共场所或公共场所使用口罩。 保护医护人员和一般人群免受高传染性病毒株的感染 关于SARS-COVID-2全球对口罩的强制执行导致数十亿个N95/外科口罩（ 一次性使用，不可降解）被丢弃在垃圾填埋场和海洋中， 对环境的重大危机。除了病毒感染外，颗粒物质（PM，即具有 纳米或微米尺寸）的化石燃料燃烧也对世界各地的 人体健康特别是小颗粒，如PM1.0或PM2.5（即尺寸分别< 1 µm和2.5 µm） 是最有毒和有害的，因为它们可以进入呼吸道的更深处， 甚至渗透到血液中在这方面，口罩也是最有效的解决方案， 保护公众健康免受工业PM和空气污染。考虑到如此巨大的过滤需求 面膜膜，传统的重和连续使用不可降解，一次性使用 口罩（例如N95和外科口罩）不仅会造成经济负担，还会造成环境污染。 每年有数十亿的永久性塑料废物被处理。除了环境问题，目前 面罩在长时间连续使用后会失去过滤功能 以及暴露在潮湿空气中，从而使口罩使用者不能保护免受病毒感染的风险。在此， 本文提出了一种新型的聚L-丙交酯（PLLA）和镁的压电复合网格 氧化物（MgO），其提供理想过滤膜的所有特性，包括（1）水分- 阻力，（2）良好的机械强度，（3）类似N95的过滤效率，（4）小的压降，（5） 可重复使用性/灭菌能力，以及（6）长期生物降解以避免对环境的任何危害。我们 主要的假设是，通过创建一个高度压电MgO/PLLA，然后采用多层的 MgO/PLLA多孔网，每层孔径/孔数可调，我们将能够生产出 具有高过滤效率和低压降的理想过滤器，类似于N95面罩过滤器。实现 在第一阶段SBIR中，我们设计了两个目标的项目。旨在 1（6个月）是在压电效应方面表征MgO/PLLA隔膜过滤器， 机械性能和多孔性。目标2（12个月）是制造多层 用MgO/PLLA复合网格图案化微孔过滤膜，并达到N-95 在过滤效率和压降方面的性能。

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.