I bet some of you have had the same idea cross your mind that we had: “If we have a breathalyzer for alcohol, why don’t we have a breathalyzer for cannabis?” We’re nanotechnology engineering alumni from the University of Waterloo. Two factors led into us deciding to pursue this idea: 1. Cannabis was being legalized across Canada and police were completely ill-prepared, so we saw an opportunity to help; 2. the science required to make this device exist was particularly interesting.
Alcohol breathalyzers are fundamentally a fuel cell where the alcohol in your breath sample is oxidized, which then produces an electrical current that the device then translates to BAC. For alcohol, this works because of Henry’s Law, which says that at any given temperature the ratio between the concentration of alcohol in the blood and that in the alveolar air in the lungs is constant.
Cannabis is a very different beast. Not only is it a non-volatile, fat-soluble molecule, but the mechanism in which THC (the psychoactive component of cannabis) appears in your breath isn’t super straight forward. Also, it is present in much lower concentrations in the breath compared to alcohol. Whereas a blood alcohol concentration of 0.08% (the legal limit in most states) might result in a concentration of 208 ppm of ethanol in the breath, a similarly impairing dose of cannabis results in 0.00001 ppm of the drug in breath.
Detecting such a low concentration is difficult, and as a result, cannabis drug use has been detected in a variety of sub-optimal ways. The state of the art is a blood draw, followed by detection of THC at a toxicology laboratory using liquid chromatography-mass spectrometry. While accurate and well-validated, this approach has several problems. First of all, since THC is fat-soluble it remains in a person’s body much longer than alcohol, especially if that person is a frequent user. Frequent users have been known to have detectable THC in their blood one week after beginning abstinence. These people are clearly not impaired all week but could be arrested and charged with a DUI based on many states laws across the US. Interestingly, police have the opposite problem with infrequent users. For most people, the concentration of THC in their system will decay quickly post-consumption. It takes around 2 hours (at best) for a police officer to get a blood draw from a suspect. At this point, many people will no longer have detectable THC in their system. Our device solves both these problems for police. Our breathalyzer uses an ultra-sensitive immunosensor to detect the minute concentration of THC in breath. Breath is the better medium for cannabis testing for several reasons. First of all, THC concentration in breath for both frequent users and infrequent users decays below detectable levels within 3-4 hours post-consumption and we have never detected THC in the baseline for any of our subjects. So our device does not incorrectly identify frequent users as impaired as blood testing can. Secondly, the breath tests can be administered quickly roadside, eliminating the risk of concentration decay seen with blood draws.
Our device comes with a reusable analyzer and a single-use disposable cartridge. It costs us $2 to make a cartridge, and police are willing to pay $20 per test. An individual will breathe into the mouthpiece, and our filter system will collect exhaled breath particles (specifically non-VOCs). Currently, we manually “extract” the THC off of the filter into a solvent liquid, but in the future, this will be automated using novel microfluidics. The solvent, with the captured THC, is then transferred to the surface of the sensor- which is an electrochemical immunoassay. When the THC is there, the output signal is different than when the THC is not there (happy to dive further into this in the comments if people are interested).
We haven’t had enough resources to run any formal trials yet to publish data, but that is changing this year. We’ve hired a contract research organization, (shout out Curebase), to help us run our very first clinical trial with blood draws. We’re going to be looking at the correlation between breath and blood concentrations, at various time intervals after consumption, to validate (or invalidate!) our preliminary in house data.
Selling to the police is notoriously difficult, but we’re imagining a world where there are one of our devices in every police car in North America. This weekend we exhibited at the IACP DAID and the response from the attendees was great! We have over 30 police departments across North America that have expressed interest in purchasing the device and that number is increasing every day.
We’re excited to hear all your questions and feedback! I encourage any questions you may have for us 🙂