Fig. 1.

Schematic overview of the portable device to sample exhaled particles. (A) Schematic representation of a person breathing into the sampling device. (B) Design of the disposable sampling device with the position of the silicon sieve indicated and kept in place by a holder consisting of an aluminium pre-heated block with O-rings for sealing. A mouthpiece is used in front, and a viral filter in between the silicon impactor and a spirometer (indicated in blue) for measuring flow rate during sampling. (C) Schematic top-view of the final sieve, 22 × 22 mm² in size, consisting of an array of 1600 nozzles with a diameter of 150 μm. (D) The non-integrated, non-monolithic impactor consists of two sieves stacked on top of each other, creating a gap of 30 μm between the two arrays of holes (the single piece, monolithic impactor is described in Fig. 4). Exhaled particles, some containing virus, are collected on the bottom sieve by inertial impaction, while air and very small particles (<300 nm) are directed to the outlet nozzles and exit without impacting. (E) Schematic overview of the used protocol for this non-monolithic version of the impactor. The bottom sieve is removed from the sample device and master mix is pipetted on top followed by a brief spin to collect the sample. The sample is transferred to a 96-well plate and an RT-qPCR is conducted using a commercial thermal cycler.