Quantitative characterisation of a portable 3D-printed bioaerosol sampler for sub-micrometre particle collection

Efficient bioaerosol sampling of sub-micrometre particles remains a major technical challenge in environmental, agricultural, and biomedical monitoring. Particles below 1 μm are of particular concern, due to their prolonged atmospheric residence times, deep lung penetration, and relevance to viral transmission and ultrafine particulate exposure. The SOLARIS bioaerosol sampler is a portable, additively manufactured hybrid cyclone–wet impaction device, previously validated for micrometre-scale bacterial aerosols. In this study, a systematic experimental framework was implemented to evaluate SOLARIS’ performance for sub-micrometre aerosols. Monodisperse polystyrene (PS) nanoparticles (NPs) of 300 nm and 500 nm were used as standardised model particles, for controlled benchmarking of upper sub-micrometre droplet-nucleus collection, alongside bacteriophage SPP1 as a complementary biological challenge. Aerosols were generated under controlled laboratory conditions, and aerosolisation efficiency was independently quantified using a reference sampler. NP recovery was assessed by Nanoparticle Tracking Analysis (NTA), while viral recovery was evaluated by plaque assay. Aerosolisation efficiency was low for both NP sizes (6.11% for 300 nm and 3.48% for 500 nm), confirming aerosol generation as a major upstream limitation for sub-micrometre particles. In contrast, SOLARIS exhibited high sampling efficiencies, achieving 88.9% and 80.2% recovery for 300 nm and 500 nm PS NPs, respectively. Viable SPP1 bacteriophage was recovered at a sampling efficiency of 13.8%, delineating the lower operational boundary of the current configuration. These results define a bounded upper sub-micrometre performance window for SOLARIS under controlled conditions. NP data should be interpreted as physical benchmarking of evaporation-derived sub-micrometre nuclei, whereas SPP1 provides a distinct viability-dependent viral endpoint.