Detection of particles in breathing air

Fig. 1: Resp-Aer-Meter / How it works

To analyze the risk of infection, the test person inhales and exhales into the measuring device for approx. 30 seconds.

The Resp-Aer-Meter sucks in the exhaled air. Before the measurement, the aspirated particles are conditioned in the aerosol conditioning area to differentiate between pure droplets (e.g., spit or water droplets) and potentially infectious particles (bacteria, viruses = solid).

To measure the particle size and concentration, the Resp-Aer-Meter works with the white light LED sensor of the Fidas^® system, which has proven itself in environmental measurements. Even the smallest particles from 150 nm are recorded individually, and their size and number are detected online.

More about the spread of virus-carrying aerosols by superspreaders can be found here .

Comparison measurements

The Resp-Aer-Meter was the subject of a scientific study involving over 300 issues. Approximately 120 people were infected with Covid-19. The study investigated the extent to which the Resp-Aer-Meter could detect infected individuals. The values are shown here in a ROC curve, with sensitivity (true positive rate) on the y-axis and specificity (false positive rate) on the x-axis. The area under the curve (AUC) of the ROC curve measures how well the exhaled aerosols perform as an indicator of respiratory infection (COVID-19 in this case).

Fig. 2: ROC curve

• Exhaled aerosols are very suitable for detecting patients with respiratory diseases: This is made clear by the high AUC of 0.8951.
  
• The steep slope of the ROC curve shows that the particle count is very well suited to distinguish infected from non-infected persons.
  
• A threshold value enables a short, clear statement of whether a person is infected (a yes/no statement comparable to a PCR test).
  
• Furthermore, an output of the Resp-Aer-Meter is an individual false positive rate.

Find here the published study "Aerosol measurement identifies SARS-CoV 2 PCR positive adults compared with healthy controls" at Frankfurt University Hospital (https://doi.org/10.1016/j.envres.2022.114417)

Publications

Further publications using the Resp-Aer-Meter can be found here:

https://www.frontiersin.org/articles/10.3389/fped.2022.941785/full

https://doi.org/10.21203/rs.3.rs-1089497/v1