A Continuous Virus Aerosol-into-Liquid Sampler (VAiLS) Integrating Twin-Vortex Condensation Growth and Wet-Cyclone Enrichment

Abstract

Airborne virus surveillance requires sampling methods that efficiently transfer nanoscale virions into a small-volume liquid while preserving infectivity. Here, we develop a continuous Virus Aerosol-into-Liquid Sampler (VAiLS) that integrates a twin-vortex condensation growth unit (CGU) with a wet cyclone (w-Cyc) to enlarge virus-sized aerosols into micrometer droplets and continuously concentrate them into a hydrosol sample, defined here as the particle-containing aqueous suspension produced by transferring aerosol particles into the w-Cyc liquid film. The CGU combines a low-temperature preconditioner (∼5 °C) with a wick-wetted growth chamber (Tg = 20–60 °C) to generate supersaturation at a high sampling flow rate (16 L/min), and the downstream w-Cyc collects the grown droplets via a stable liquid film. Using KCl nanoparticles as model aerosols, the number-weighted total collection efficiency increased from 7.3% (w-Cyc only) to 31.0, 64.4, and 70.4% at Tg = 20, 40, and 60 °C, respectively, with no appreciable dependence on inlet relative humidity (16.8–71.8%). For airborne viruses, VAiLS achieved maximum collection efficiencies at Tg = 40 °C (MS2: 93 ± 0.6%; phi 6: 90 ± 2.1%) and produced much higher infectious concentrations than a BioSampler (3.9 × 103-fold for MS2 and 1.2 × 103-fold for phi 6). Relative virus viability remained >92% for most conditions, decreasing only for phi 6 at Tg = 60 °C (5.8 ± 4.37%). These results demonstrate that VAiLS enables high-flow, high-enrichment, infectivity-preserving sampling compatible with plaque assays and qPCR.