Marijuana breathalyzer using nanotechnology to detect THC developed by University of Pittsburgh researchers

The prototype looks similar to a breathalyzer for alcohol and has been successfully tested in the laboratory but still has a long way to go when it comes to being mass-produced for law-enforcement to use


                            Marijuana breathalyzer using nanotechnology to detect THC developed by University of Pittsburgh researchers

While there are readily available breathalyzers to detect whether an individual is under the influence of alcohol, the same did not hold true for measuring the effect of marijuana -- that is until now. A team of researchers at the University of Pittsburgh have come up with a device to tell if someone smoked weed before getting behind the wheel.

"An interdisciplinary team from the Department of Chemistry and the Swanson School of Engineering has developed a breathalyzer device that can measure the amount of tetrahydrocannabinol (THC), the psychoactive compound in marijuana, in the user’s breath," a press release from the university said. 

The release added that with the absence of any kind of tool to perform such a test, experts had to rely on a person's blood, urine or hair samples. As a result, such tests could not be conducted out on the field and neither did they yield instant results. However, the test only detected if the user had inhaled the drug recently and not whether the person was under the influence of marijuana. 

With 33 states in the United States having legalized pot in some form, arose the need for a more comprehensive method of testing to detect THC levels in the user's blood by the police during DUI stops. The newly developed breathalyzer used carbon nanotubes -- tiny tubes of carbon 100,000 times smaller than human hair -- whose surfaces bind with the THC molecule, along with other molecules in the breath, changing their electrical properties.

The rate at which the electrical currents recovered then signaled whether THC was present. “The semiconductor carbon nanotubes that we are using weren’t available even a few years ago,” said Sean Hwang, lead author on the paper and a doctoral candidate in chemistry at the university. “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.”

Ervin Sejdic, Ph.D., associate professor of electrical and computer engineering at the Swanson School of Engineering, who helped co-create the prototype, said, “Creating a prototype that would work in the field was a crucial step in making this technology applicable. It took a cross-disciplinary team to turn this idea into a usable device that’s vital for keeping the roads safe.” 

The prototype, that looks similar to a breathalyzer for alcohol, has been successfully tested in the laboratory and still has a long way to go when it comes to being mass-produced for law-enforcement to use. “In legal states, you’ll see road signs that say 'Drive High, Get a DUI,’ but there has not been a reliable and practical way to enforce that. There are debates in the legal community about what levels of THC would amount to a DUI, but creating such a device is an important first step toward making sure people don’t partake and drive," Alexander Star, Ph.D., professor of chemistry with a secondary appointment in bioengineering, who led the development of the prototype, said.

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