  To evaluate the role of common substrates in the transmission of respiratory
viruses, uniformly distributed microdroplets of artificial saliva were
generated using an advanced inkjet printing technology to replicate the aerosol
droplets, and subsequently deposited on five substrates, including glass, PTFE,
stainless steel, ABS, and melamine. The droplets were found to evaporate within
a short timeframe, 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 and Youngs modulus, supporting the proposed
coreshell structure of the nuclei. We suggest that appropriate antiviral
surface strategies, e.g. functionalisation, 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.
