Chamber design of a portable breathalyzer for disease diagnosis

Breathalyzers allow, in a non-invasive way, to study the molecules present in the breath, enabling the diagnosis of some diseases due to the presence of low concentrations (ppb) of certain volatile organic compounds (VOCs). Developing these devices presents significant challenges, but the benefits of these techniques are tremendous, as they provide a noninvasive and cheaper diagnostic approach. The operation of these devices is simple; the patient only has to blow through a disposable mouthpiece into the measurement chamber, which houses the sensors that analyze the concentration of VOCs in individuals’ breath. Tomás Palacios group (Massachusetts Institute of Technology, Cambridge, United States) has built a graphene- based sensor array that can accurately measure the presence and concentration of different chemicals of interest. This bachelor’s thesis develops a chamber design that allows this sensor to be used as a portable breathalyzer for disease diagnosis. This system could provide a non-invasive, cheap and rapid approach to disease diagnosis. Although significant research has been done in this field over the years, none has focused on the optimal chamber design of these devices, which must optimize contact between sensors and air samples and address issues such as moisture, air velocity control, recirculation and turbulence. This work studies the airflow properties in different chamber models and creates, with a careful component selection, a reusable in situ breath analyzer design with the help of fluid mechanics simulations and experiments with the analysis sensors.