  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.
