Insights on drying and precipitation dynamics of respiratory droplets in the perspective of Covid-19

Abstract

We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain fundamental insights into the infectivity of air borne nuclei during the Covid-19 pandemic. Evaporation experiments are performed with salt-water solutions seeded with a viral load of inactive nanoparticles in an acoustic levitator. We seek to emulate the drying, flow and precipitation dynamics of such air borne mucosalivary droplets. Observations with the surrogate fluid are validated by similar experiments with actual samples from a healthy subject. A unique feature emerges with regards to the final crystallite dimension; it is always 20-30% of the initial droplet diameter for different sizes and ambient conditions. The preserved precipitates from levitated droplets show that 15% of the total virion population remain dispersed on the outer surface of air-desiccated air borne nuclei. This fraction increases to ~90% if the respiratory droplets (of larger initial size) settle on a surface and then evaporate in the sessile mode.

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References in corpus (3)

• Modeling ambient temperature and relative humidity sensitivity of respiratory droplets and their role in Covid-19 outbreaks
• Likelihood of survival of coronavirus in a respiratory droplet deposited on a solid surface
• Analyzing the dominant SARS-CoV-2 transmission routes towards an ab initio SEIR model

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• Dispersion of Free-Falling Saliva Droplets by Two-Dimensional Vortical Flows
• Dynamics of Droplet Generation from Corneal Tear Film during Non-contact Eye Procedure in the Context of COVID-19
• Airborne Virus Transmission: Increased Spreading Due to Formation of Hollow Particles