A Robot Assisted High-flow Portable Cyclone Sampler for Bacterial and SARS-CoV-2 Aerosols

Airborne transmission of infectious diseases attracts great attention since the COVID-19 pandemic. Yet, there has been an intense dispute about aerosol transmission of the disease, which is largely due to lack of qualified instruments for studying the subject. Air sampling plays a critical role in all air pollution related study, and particularly critical for airborne pathogen detection. Here, we designed and evaluated a portable and high volume (400 L min-1) cyclone sampler named as Yao-CSpler using aerosolized Polystyrene (PS) uniform microspheres, Bacillus subtilis var. niger, Pseudomonas fluorescens, and both indoor and outdoor air particles. The experimental cutoff size of the Yao-CSpler was demonstrated to be 0.58 m (while the calculated theoretical value is 1.84 m), and the sampler has shown stable microbial collection performances for bacteria, fungi, and even viruses. The sampler had a physical collection efficiency of close 100% for particles of larger than 1 m. Jet-to-liquid distance and sampling duration were shown to substantially influence the sampler performance. Given the same sampling duration, the performances of the Yao-CSpler were significantly higher than those of the traditional BioSampler (SKC Inc.) in terms of samples' bacterial diversity. The developed sampler coupled with a robot has been successfully applied to sampling airborne SARS-CoV-2 in both Wuhan and Beijing during the COVID-19 outbreaks. With a high sampling flow, the Yao-CSpler was shown to be able to collect the SARS-CoV-2 with a detectable concentration level down to 9-219 viruses m-3 in clinical settings housing COVID-19 patients. Further more efficient bioaerosol sampler, which is able to rapidly capture low level pathogenic agents, is urgently required to better understand and confront airborne transmission of infectious diseases.