Drying Out Microbe-Filled Droplets

Ocean sprays, coughs, and sneezes are just a few of the ways that droplets full of bacteria and salt can get aloft on a breeze. How do these bacteria stay viable even as their droplet evaporates? That’s the question behind this video’s research.

When a bacteria-laden droplet or a salt-laden droplet dries, the evaporating droplet’s contact area shrinks, leaving behind only a concentrated lump of bacteria or salt. But when droplets contain both salt and bacteria, the drying droplet’s contact line gets pinned, leaving a larger area stain. The bacteria’s presence seems to promote crystallization of the salt, which–in turn–traps water in isolated spaces, perhaps helping the bacteria stay viable longer. (Video and image credit: R. Ran et al.)

A floating droplet on a liquid substrate can oscillate when the surface temperature is spatially modulated. The droplet shape and motion become locked to the modulation period.

🔗 https://doi.org/10.1063/5.0326112

#FluidDynamics #MarangoniEffect #Droplets #NonlinearPhysics #InterfacialFlows