A Virucidal Face Mask Based on the Reverse-flow Reactor Concept for Thermal Inactivation of SARS-CoV-2.

While facial coverings over the nose and mouth reduce the spread of the virus SARS-CoV-2 by filtration, masks capable of viral inactivation by heating could provide a complementary method to limit viral transmission. In this work, we introduce a new virucidal face mask concept based on a reverse-flow reactor driven by the oscillatory flow of human breath. The governing heat and mass transport equation are formulated and solved to analyze designs that evaluate both viral and CO2 transport during inhalation and exhalation. Given limits imposed by the volume and frequency of human breath, the kinetics of SARS-CoV-2 thermal inactivation, and human safety and comfort, heated masks may inactivate SARS-CoV-2 in inflow and outflow to medical grade sterility. We detail one particular design, with a volume of 300 mL at 90 $^\circ$C, that achieves a 3-log reduction in viral load with minimal viral impedance within the mask mesh, with partition coefficient around 2. This study is the first quantitative analysis of virucidal thermal inactivation within a protective face mask and addresses a pressing need for new approaches for personal protective equipment during a global pandemic.