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Efficient Facemask Sterilization via Forced Ozone Convection

During the beginning of 2020, the Covid-19 pandemic took the world by surprise, rapidly spreading undetected between and within many countries and wreaking havoc on the global economy both through death tolls and lockdowns. Healthcare professionals treating the coronavirus patients grapple with a massive and unprecedented shortage of Facepiece Respirators (FPRs) and other personal protective equipment (PPE), which act as fundamental tools to protect the health of the medical staff treating the patients affected by the coronavirus. While many FPRs are designed to be disposable single-use devices, the development of sterilization strategies is necessary to circumvent future shortages. Here, we describe the development of a plasma-based method to sterilize PPE such as FPRs with ozone. The novel design uses a flow-through configuration where ozone directly flows through the fibers of the PPE through the maintenance of a pressure gradient. Canonical ozone-based methods place the mask into a sealed ozone-containing enclosure but lack pressurization to permeate the mask fibers. In this device, ozone is created through an atmospheric pressure Dielectric Barrier Discharge (DBD) fed with compressed air. Due to limited supply and clinical need of FPRs, we demonstrated sterilization with surgical masks. We demonstrate rapid sterilization using E. coli as a model pathogen. A flow-through configuration enables a >400% improvement of the sterilization efficiency with respect to the canonical approach. This method has potential for a broad and cost-effective utilization. Using the power supply from a readily available plasma ball toy, a plastic box, a glass tube, steel mesh, and 3D printed components, we designed and tested an extremely affordable portable prototype system for rapid single mask sterilization which produced comparable results to its large high-cost equivalent.