Efficient and Robust Metallic Nanowire Foams for Deep Submicron Particulate Filtration

The ongoing COVID-19 pandemic has unleashed global disruptions and profoundly changed our way of life. Central to the rapid spread of this respiratory infection is the transmission by airborne viral particles. There is an urgent need for the development of efficient, durable, reusable and recyclable face masks for the deep submicron size range. Here we report the realization of efficient particulate filters using nanowire-based low-density metal foams with tunable porosity and density (0.1%-30% of bulk density) which combine extremely large surface areas with excellent mechanical properties [1]. The metal foams exhibit outstanding filtration efficiencies (>96.6%) in the PM_0.3 regime and near 100% efficiency for much of the 0.1-1.6 micron sized particle range, with a breathability comparable to N-95 respirators. The foams can also be easily cleaned, as well as reclaimed and recycled at the end of their life cycle. These attributes make such metal foams promising filters for combating COVID-19 and other types of airborne particulates. Our mask design based on such foams has been selected by BARDA-NIOSH as a Phase 1 Winner of the Mask Innovation Challenge [2].