For EBC related studies, the first key step is the collection of exhaled breath. Over the years, a variety of devices (Table S1 , Supporting Information) were developed including Rtube collection system (Respiratory Research, Inc, Charlottesville, VA) and EcoScreenH condenser (Erich Jaeger Gmbh, Wurzbur, Germany). Typically, these devices would be able to collect 1000 ml of EBC samples within about 10 min, however the collection often comes with a lengthy procedure and a higher cost. For example, use of the EcoScreen involves 7 steps: 1) turn on to cool, 2) clean collection tube, 3) clean condensation chamber insert, 4) retrieve cooling sleeve from freezer, 5) sample collection, 6) sample storage and transport, 7) removal of sample (Respiratory Research, Inc, Charlottesville, VA). The RTube eliminates the first 3 steps, but each collection still requires 10 min and costs $23.25 (Respiratory Research, Inc, Charlottesville, VA) compared to 31 min and $47.17 per collection for the EcoScreen. These collection devices are generally expensive, e.g., the EcoScreen costs around $9000. A recent study compared the sampling efficiency of the Rtube (widely used EBC collection device) with that of throat swab method, showing detection rates of 7% and 46.8% for the Rtube and the throat swab method, respectively [20] . It was suggested that the RTube is not applicable for viral detection in exhaled breath [20] . In addition, condenser coatings [34] , sampling temperature [35] and sampling times [36] were shown to affect physical collection efficiencies of available EBC collectors. Among others, the noted problems with these available EBC collection devices are the device availability, reusability and possible cross contamination [37] , which would negatively impact their wide applications. In addition, EBC collection is strictly limited to the method condensation only in most studies [38] . To fully utilize EBC in early disease screening, diagnosis and environmental exposure assessment, simple yet efficient EBC collection device using different methods and biological characterization of the EBC sample are needed.