Design, development, and functional characterization of cold plasma systems to reduce airborbe transmission of hospital acquired infections & COVID-19

This thesis investigates innovative strategies to improve indoor air quality, focusing on cold atmospheric plasma (CAP) as an alternative or complementary solution to traditional air treatment methods. The emergence of airborne diseases like COVID-19 and hospital acquired infections (HAIs) underscores the need for effective decontamination systems. CAP, which produces reactive species such as charged particles, radicals, and UV, has shown strong antimicrobial properties, particularly through reactive oxygen and nitrogen species (RONS) that inactivate microorganisms via multiple mechanisms. The dissertation is divided into three main sections. Chapter 1 presents a systematic review of CAP applications in virology, analyzing 110 studies published between 2000 and 2023. The review highlights CAP’s effectiveness in inactivating various viruses, including enveloped and non-enveloped, DNA and RNA types, through viral particle damage, replication disruption, and modulation of the host immune response. Chapter 2 regards the design and characterization of a direct dielectric barrier discharge (DBD) plasma source developed for decontaminating bacterial and viral bioaerosols. Serving as a proof of concept for the project, this device was among the first CAP prototypes to undergo biological testing against the SARS-CoV-2 virus. This prototype demonstrated a Log Reduction of 3.7 for bacterial bioaerosols and effectively inactivated SARS-CoV-2. Chapters 3, 4, and 5 describe the scaling-up of the proof-of-concept into two devices: the Rotating DBD, a tabletop unit for diverse environments (e.g. hospital rooms, offices, residential spaces), and the InDuct plasma source, designed for installation in ventilation ducts. Both devices were electrically characterized and their gas-phase chemistry was evaluated using various diagnostic techniques. They demonstrated over 99.9% efficacy in deactivating bacterial bioaerosols, including Staphylococcus epidermidis.