Characterization and Optimization of a Novel UV-C LED Aerodynamic Device for Airborne Microbe Viability Abatement

The escalation of the COVID-19 outbreak has significantly increased research into the transmission of airborne infectious diseases in indoor settings, underscoring the urgent necessity for affordable and efficient methods of air disinfection. The aim of the present work is the development of a complete framework based on designed experiments for exploring and optimizing the bioaerosol removal and inactivation efficiency of a novel air disinfection device. This device combines the aerodynamic effect of a three-dimensional vortex structure with UV-C radiation provided by commercially available UV-C light-emitting diodes (UV-C LEDs). The system was designed and tested to locally maintain a high radiation intensity that is suitable for bioaerosol disinfection. A controlled experimental laboratory model of bioaerosol aerosolization was set up by using an impinger medical vibrating nebulizer, a cylindrical chamber for bioaerosol travel, and an SKC BioSampler for collecting microorganisms capable of replicating. A nonpathogenic strain of E. coli (BL21-DE3) was used as a model of airborne bacteria. The inactivation efficiency was assessed based on the enumeration of the colonies originating from viable E. coli. Interactions between analytical factors and their optimal levels were investigated by using sequential D-optimal designs adapted to domain constraints and previous computational simulations of the aerodynamic performance of the device. Five experimental variables (the concentration of aerosolized bacteria; the size of aerosol particles; the volumetric airflow; the power of the LEDs; and two configurations of the device) were considered as factors in the optimization process. Response surfaces allowed for the identification of the ideal working conditions to maximize the efficiency of the device, an essential requirement for the device’s future exploitation in real-world settings.