Characteristics of respiratory microdroplet nuclei on common substrates

Alexandros Kosmidis Papadimitriou, Shaojun Qi, Ophelie Squillace, Nicole Rosik, Mark Bale, Peter Fryer, Jason Zhang

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To evaluate the role of common substrates in the transmission of respiratory viruses, in particular SARS-CoV-2, uniformly distributed microdroplets (approx. 10 µm diameter) of artificial saliva were generated using an advanced inkjet printing technology to replicate the aerosol droplets and subsequently deposited on five substrates, including glass, polytetrafluoroethylene, stainless steel, acrylonitrile butadiene styrene and melamine. The droplets were found to evaporate within a short timeframe (less than 3 s), which is consistent with previous reports concerning the drying kinetics of picolitre droplets. Using fluorescence microscopy and atomic force microscopy, we found that the surface deposited microdroplet nuclei present two distinctive morphological features as the result of their drying mode, which is controlled by both interfacial energy and surface roughness. Nanomechanical measurements confirm that the nuclei deposited on all substrates possess similar surface adhesion (approx. 20 nN) and Young's modulus (approx. 4 MPa), supporting the proposed core–shell structure of the nuclei. We suggest that appropriate antiviral surface strategies, e.g. functionalization, chemical deposition, could be developed to modulate the evaporation process of microdroplet nuclei and subsequently mitigate the possible surface viability and transmissibility of respiratory virus.
Original languageEnglish
Article number20210044
JournalInterface Focus
Issue number1
Early online date10 Dec 2021
Publication statusPublished - 6 Feb 2022

Bibliographical note

Funding Information:
This work was supported by the Engineering and Physical Science Research Council (grant no. EP/V029762/1). Z.J.Z. thanks the Royal Academy of Engineering for an Industrial Fellowship (award no. IF2021\100). Acknowledgements

Publisher Copyright:
© 2021 The Authors.


  • respiratory
  • microdroplet
  • nuclei
  • substrates
  • transmission
  • virus


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