UV irradiance modeling, simulated inactivation studies, and experiments demonstrate better efficacy of the UVC robot...

Autonomous UVC-based disinfection robots have gained widespread use after the COVID-19 outbreak to limit infectious disease transmission. Although several semi-automatic and fully automatic UVC robots are employed for surface disinfection in high-risk areas, their efficacy is restricted because they cannot disinfect complex regions of contaminated surfaces that are distant, located at different heights, in narrow pathways, or within shadow zones. This paper reports the design, development, and implementation of a Robotic Disinfection System with Movable Ultraviolet Light Radiating Arms (RwMA) to address these limitations. To quantify the performance of RwMA, a simulated inactivation study using an extended UVC irradiance model and experiments were conducted, and results were compared with a conventional UVC-based Disinfection Robot without Movable Arms (RoMA). The simulated study quantified UVC irradiance and pathogen inactivation time of RwMA and RoMA for commonly contaminated surfaces such as "Chair Back," "Chair Seat," "Chair Armrest," and "Chair Backrest" while disinfecting a row of chairs. RwMA delivered high and nearly uniform irradiance on all chair surfaces, whereas RoMA produced extremely low irradiance that further decreased for distant chairs due to distance and shadowing. For 4-5 log inactivation of bacteriophage MS2 on a row of chairs, RwMA required only 11.873 s, whereas RoMA needed 418.223 s (6.97 min), which is significantly higher. As anticipated by simulated studies, experimental evaluation using bacteriophage MS2 confirmed consistently higher and more uniform infectivity reduction by RwMA across all near and distant chair positions, unlike RoMA. These results support the adoption of RwMA for rapid and effective disinfection in shared environments.