The Development of a Delta-9-THC Colorimetric Breathalyzer using 3D Printing Manufacture

According to the 2021 World Drug Report cannabis is one of the most widely used drugs worldwide. UNODC estimates that almost 4% of the global population aged 15–64 years used cannabis at least once in 2019. As a result of Δ9-THC’s ability to impair performance and decrease the ability of drivers, and the current lack of correlation between driving impairment and Δ9-THC concentrations in blood, the necessity of a quick and portable detection method to identify Δ9-THC non-invasively from drivers is imperative. The development of the Δ9-THC breathalyzer was based on an additive manufacturing solid device made by 3D printing. Five different polymerizable resins and three different cannabinoid-specific dyes were analyzed. Resins were treated with varying concentrations of Fast Blue B, Fast Blue BB, and Fast Blue RR dyes, followed by treatment with 50 ng of Δ9-THC to optimize the system. Cartridges were printed using an ELEGOO 3D printer® and were covered with ballistic gelatin and dye. Color formation was captured using various imaging techniques including a Canon flatbed scanner and a Raspberry Pi equipped with a camera module. The intensity of the color was analyzed using ImageJ®. The analytical signal, stability of the dye, influence of the shape of the cartridge, and the differences between the dyes were evaluated. Of the dyes, Fast Blue B and BB were the best options to achieve linearity between increasing concentrations. Fast Blue BB resulted in higher variability than Fast Blue B, however, Fast Blue BB can fluoresce with THC and not CBD, allowing for theoretical differentiation. The optimal concentrations for Fast Blue B and BB were 2% and 2.5% respectively. Preliminary results showed the capacity of the cartridge to react positively to a concentration of 50 ng of Δ9-THC. The results obtained in this work are the foundation needed to construct a reliable semi-quantitative breathalyzer for Driving under the Influence of Drugs (DUID) cases in the U.S.