Development of handheld microfluidic breath-analyzer to detect tetrahydrocannabinol and other target volatile organic compounds

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Perspectives on cannabis have shifted in recent decades due to increased understanding of its medicinal qualities and mounting public support for legalization of recreational use. Typically, cannabis use is separated into two categories, with medicinal users seeking to reduce symptoms of their ailment and recreational users desiring euphoric effects. Consequently, the amount of psychoactive chemicals (e.g., tetrahydrocannabinol (THC)) in the blood stream can depend on the type of user, which is an important distinction when testing for impairment. Current technology focuses on blood and saliva samples, which are unfavourable due to either invasive sample collection or poor accuracy. Breath analysis is a promising alternative as it is both non-invasive and, since the concentration of THC in breath closely matches the levels present in blood, it provides accurate results. However, breath analysis has many challenges, including controlling for humidity and discriminating between chemicals in exhaled breath. Our technology pairs a metal-oxide semiconductor with a microfluidic channel of specific geometry and coatings; this provides a highly sensitive and selective method of detection that is much more portable than conventional methods, such as gas chromatography. We will develop a solution for monitoring THC in breath in the following objectives: (1) improve response time of existing gas sensor technology, (2) control for signal interference (e.g., humidity), (3) develop cartridges for sample collection, (4) use machine learning to calibrate device to human breath, (5) package sensor within a ruggedized portable setup, and (6) validate prototype and correlate breath samples to plasma concentration of THC in collaboration with industry partners. Ultimately, this technology will not only provide a non-invasive tool that allows cannabis users to be more aware about their level of exposure but can also be packaged to serve as a screening tool to help enforce designated exposure limits in workplaces and by law enforcement. This translates into individuals having a better understanding of their cannabis intake, safer roads and work environments, as well as having a new tool to study the complexity of THC-induced impairment.