Problem Description

The work plan includes many phases. Initially, fluid dynamics of bacteria-laden droplets will be studied to ascertain the effect of flow on the accumulation, coagulation, and spatio-temporal evolution of bacteria or viruses. The studies will involve contact-free environments and hydrophilic substrates in the context of fomites. The flow-bacterial coupling in the various physiological mediums like blood, mucin, etc., and the intricacies of bacterial motion and deformation dynamics will be carefully studied. In parallel usage of flow stress like vibration and shock on bacteria will be analyzed in detail.

In the next phase, detailed biological studies will be performed. Bacteria can be disseminated through various routes of infection. Aerosol and fomites are the most stealthy and important ways for bacteria to get inside the body. The biological fluids carrying the bacteria can change the virulence gene expression in them, thereby leading to enhanced infection. Therefore it is very important to understand how common biological fluids like nasal secretion, saliva droplets, etc., carry the bacteria when dropped onto the fomites and dry, and direct inhalation of aerosols can be a source of potent infection. The hierarchy in the bacterial virulence mechanism may be the way by which it arranges itself in the precipitates followed by the virulence expressions. Flow cytometry, SEM imaging, AFM imaging, etc. will be done to answer these questions. Cell culture and Animal model will be used to validate the infection. 

The first work was on, "Spatiotemporal evaporating droplet dynamics on fomites enhances long-term bacterial pathogenesis", by Sreeparna. et.al is published in Nature Communications Biology 2021. Following this, a comparative study between two modes of bacterial droplet evaporation i.e. in  contact free environment and on a hydrophilic substrate has been performed. The study examines the mass transport, deposition pattern of bacteria in the precipitates, survival of bacteria in precipitates, and their virulence. The results are quite interesting and the study will also help guide the mechanical knowledge of bacterial fluid evaporation and its overall consequence. This work is communicated for publication in the Soft Matter Journal.

Further down the line, the focus is on bacteria-laden droplets in a contact-free environment with varying relative humidity conditions which provides a physiological relevance to the study with respect to global conditions. Concurrently, studies based on the different diameters during the evaporation of the droplet were performed.

The effect of the substrate temperature on bacteria-laden sessile droplets is studied in this course of work. The signature bacterial patterns, survival, and infection for respective substrate temperatures are deciphered.