Developing a Mechanical Emulator to Simulate SARS-CoV-2 Droplet Cloud Formation and Propagation

Project Summary Our understanding of pathogen laden droplet/particle cloud formation and propagation remains limited. Several approaches including use of computational tools, experimental tests by tracking ejected droplets from subjects during emissions, and limited simulators by pumping and dispersing powders, have been implemented. Yet there is no adequate respiratory emission emulator that could holistically replicate saliva liquid atomization and the breakup process corresponding to each main explosive event such as sneezing, coughing, or speaking loudly. In this proposal, our overarching aim is to fill this gap by developing and testing a spray system that emulates respiratory events. This device can be used as an alternative subject to mimic the main respiratory events with higher flexibilities in terms of availability/safety, superior droplet tracking, and wider representation of subjects. To develop this new device, three specific aims are proposed: Aim 1. Design and fabricate the emulator spray system capable of simulating respiratory events in terms of droplet size & velocity distributions and counts of the formed droplet cloud. The system includes a hardware and a PC-based control unit to enforce desired air pressure profile, particular to each type of emission and ensued droplet cluster. Aim 2. Characterize emulator ensued plume and compare it to ejected droplet cloud from actual respiratory emissions using high-speed imaging and laser diffraction. Aim 3. Find relevant pulsating pressure and flowrate profiles to emulate typical explosive respiratory events. The long-term goal of the project is to add more features to the device (e.g. adding motions) to gradually approach the actual phenomena. This novel proposed emulator can be used to mimic flow and evolution of pathogen laden droplets; therefore, it provides opportunities for training healthcare workers and the public on the best preventative practices and design of adequate ventilation systems. Furthermore, the project aids faculty and underrepresented students at Tuskegee University (a Historically Black University) in developing/testing a novel mechanical emulator to better understand a virus propagation route through engineering tools. It also helps students to see how engineering and other disciplines can come together and contribute to a public health crisis. 1