Characterization of a cold atmospheric plasma generated by a custom-design dielectric barrier discharge reactor for bioaerosol decontamination

Cold Atmospheric Plasma (CAP) based technology represents a promising approach for bioaerosols decontamination. CAPs generates a mixture of ions, electrons, and reactive species at room temperature, which in contact with the bioaerosols lead to the inactivation of microorganisms through cell membrane disruption and oxidative stress. Studies have shown that CAPs are effective in reducing airborne bacteria, viruses, and fungal spores. Nevertheless, few studies focus on plasma reactors optimization. In this context, the development of a new CAP reactor, named GAPS - Grid-like Air Plasma Sanitizer, could represents a promising advancement in these field. This study presents the design, development, and characterization of GAPS, specifically engineered for continuous bioaerosol treatment. The research aimed to enhance the interaction between GAPS and bioaerosols to maximize inactivation efficiency. Computational Fluid Dynamics (CFD) simulations provided essential insights into airflow patterns, ensuring uniform bioaerosol distribution within the reactor chamber and effective plasma interaction with the airflow. At full capacity, the operating specific power was found to be 0.014 W/cm^{2}. Chemical analysis of the plasma environment, conducted using Fourier-transform infrared (FTIR) spectroscopy, identified the generation of reactive oxygen and nitrogen species (RONS). Specifically, GAPS produced approximately 9 ppb of $O_3$ and less than 2 ppm for $N_{2}O$ when the system reached steady-state conditions. The CAP DBD reactor's biological efficacy was validated through the CFU counting method, which determined a 4-log reduction of aerosolized non-pathogenic Escherichia Coli, a well-known representative gram-negative bacteria. Notably, the reactor's Electrical Energy per Order (EEO) was measured to be of 2x10^{-4} kWh/m^{3} per order, two order of magnitude lower than other plasma-based air sanitization devices found in literature. While these results are promising, several challenges remain. Variability in bioaerosol composition and environmental conditions may affect disinfection efficacy, highlighting the need for further research to optimize reactor performance across different scenarios.