Researchers at the University of Pittsburgh create marijuana breathalyzer
As recreational marijuana legalization becomes more prevalent throughout the U.S., concern regarding methods to enforce DUI laws has received national attention. Law enforcement officials lack the ability to detect marijuana in driving-related situations. This inability to determine marijuana exposure in the field marks an important differentiation to that of alcohol consumption, which relies on a breathalyzer to detect alcohol. New research from the University of Pittsburgh is aiming to tackle this problem for law enforcement and develop the first breathalyzer for marijuana.
The Department of Chemistry and the Swanson School of Engineering have teamed up to design a breathalyzer device that can measure the amount of tetrahydrocannabinol (THC) in the user's breath. Limitations of current marijuana testing rely on blood, urine and hair samples which impede testing performed in the field. Another limitation of current testing is that tests can only reveal recent marijuana use, but it cannot determine if the individual is currently under the influence.
The innovative THC breathalyzer uses carbon nanotubes to bind to THC molecules, along with other molecules located in the individual’s breath, altering the nanotube's electrical properties. The speed at which the electrical currents recover is then used to determine whether THC is present. These nanotechnology sensors can detect THC at levels equal to, if not better, than levels detected by mass spectrometry.
"The semiconductor carbon nanotubes that we are using weren't available even a few years ago," says Sean Hwang, lead author on the paper and a doctoral candidate in chemistry at Pitt. "We used machine learning to 'teach' the breathalyzer to recognize the presence of THC based on the electrical currents recovery time, even when there are other substances, like alcohol, present in the breath."
Hwang is a member of the Star Lab, which directed by Alexander Star, Ph.D., professor of chemistry with a secondary appointment in bioengineering. The group partnered with Ervin Sejdic, Ph.D., associate professor of electrical and computer engineering at the Swanson School of Engineering, to develop the prototype of the THC breathalyzer.
"Creating a prototype that would work in the field was a crucial step in making this technology applicable," says Dr. Sejdic. "It took a cross-disciplinary team to turn this idea into a usable device that's vital for keeping the roads safe."
The THC breathalyzer prototype designed very similar to that of a breathalyzer for alcohol. The researchers are still testing the prototype but are optimistic that it will move towards manufacturing promptly.
If you would like to reference the original paper please see, "Tetrahydrocannabinol (THC) Detection using Semiconductor-enriched Single-Walled Carbon Nanotube Chemiresistors," (DOI: 10.1021/acssensors.9b00762) which was published in the journal ACS Sensors and was coauthored by Sean Hwang, Long Bian, David White, Seth Burkert, Raymond Euler, Brett Sopher, Miranda Vinay and Alexander Star, from the Department of Chemistry, and Nicholas Franconi, Michael Rothfuss, Kara Bocan, and Ervin Sejdic, from the department of Electrical and Computer Engineering.