Fig. 1.

The airborne virus detection scheme includes three steps: collection & lysis, RNA enrichment, and amplification & detection. (a) Exploded view of the setup for airborne virus collection. The virus aerosols were enlarged by VIVAS and impinged directly into the lysis buffer housed in the SPAD collector (see Fig. 2 for the detail). A laminated paper device (with an exploded view in the inset on the right) was attached to the bottom of the collector for RNA enrichment. (b) After collection, the collector/paper device were separated from VIVAS, assembled with the buffer unit (top) and placed on top of an absorbent pad (bottom) for aerosol collection and virus detection. The buffer unit was then rotated to discharge the binding buffer into the collector (see Fig. 3 for the valving mechanism). The laminated paper device underneath the collector would enrich the virus RNA from the lysate while the waste was absorbed by the absorbent pad. Once the lysate filtration was completed, the buffer unit was rotated twice to discharge the two wash buffers sequentially. (c) The laminated paper device with enriched RNA was peeled from the collector and taped onto a well layer to form a RNA amplification device for RT-LAMP. After adding RT-LAMP amplification buffer and incubation, resultant amplicons could be detected colorimetrically. The 3D-printed sample preparation unit in (b) and the paper-based amplification unit in (c) form SPAD.