High-efficiency monitoring of respiratory viruses in a single exhaled breath

Exhaled breath (EB), as a non-invasive biological sample, has garnered attention for diagnosis and monitoring respiratory diseases. However, efficiently collecting EB viruses for downstream detection remains a key challenge. This study introduced a novel Phase-change Drywall Cyclone Sampler (PDC-sampler), which was designed and optimized through airflow control to integrate condensation with drywall cyclone gas-liquid separation. The PDC-sampler efficiently collects viral particles from EB (8-10 μL per single EB (SEB)) without requiring a sampling liquid solution. When combined with the gold-standard reverse transcription-quantitative polymerase chain reaction (RT-qPCR), it enabled routine positive detection in infected individuals (≥ 10 ³ copies/SEB). By coupling with the low-cost microfluidic electrophoretic virus enrichment chip or the high-cost and highly sensitive droplet digital PCR (ddPCR), the detection limit of EB viruses was reduced to 5-9 copies/SEB, which is an order of magnitude lower than the minimum viral concentration required for infection (~ 10 ² copies/SEB). Notably, tests on coronavirus disease 2019 (COVID-19) and influenza-infected volunteers demonstrated performance comparable to or better than throat swabs, validating the PDC-sampler’s effectiveness in real-world applications. This study provides an efficient, automated, and non-invasive solution for the early diagnosis, transmission mechanism study, and large-scale screening and monitoring of respiratory diseases.