Characterization and modeling of aerosol sample collection from human breath

The global corona pandemic has stressed the importance of respiratory droplets in the spreading of infectious diseases. While transmission through aerosols (small liquid droplets) is difficult to demonstrate directly, we at imec developed a portable sampling technology to directly detect SARS-COV-2 from exhaled breath using a silicon impactor (doi: 10.1016/j.bios.2022.114663). Besides viral diseases, certain bacterial diseases are also believed to be transmitted via aerosols from exhaled breath. Furthermore, other analytes of interest (certain biomarkers that may give indications to a subject’s state of health) may be present in aerosols. Despite the importance, the physics of aerosols and breath exhalation remain poorly studied. Understanding how to better process, handle and collect aerosols may enable further insights into disease transmission and opens the door to diagnostic methods that currently aren’t widely available or practical to implement using current technologies in a health care setting.

The portable sampling technology that imec developed is based on inertial impaction of aerosols in the air (from the breath of a human subject) onto the surface of a microfluidic device.  The flow is turbulent through parts of the collection device, but laminar through the inertial impaction unit within the breath sampler.  The focus of this PhD will be to study and understand how the aerosols are transported through the sampling device and are collected in the impactor unit.  Understanding the size range of aerosols that are collected within the impactor unit and the size distribution being lost through the breath sampler device prior to the impactor are of key importance. The first aim is to study these aspects both experimentally and numerically through computational fluid dynamics (CFD) simulations.  Optimization of the design of the aerosol sampler device and impactor unit also fall within the scope of this PhD topic.

It is anticipated that the student will spend 40% of the time on numerical simulation tasks, 50% on experimental investigation, and 10% on literature review/publications. Qualified applicants should have an Engineering or Physics background and ideally, prior knowledge of experimental and numerical methods applied to fluid mechanics including both laminar and turbulent flows.