A fuel cell sensor developed by UCLA researchers can detect the presence of THC by oxidizing it to produce an electric current.

A chemist from the University of California, Los Angeles, and colleagues are one step closer to developing a handheld device that can detect THC on a person’s breath after they’ve smoked marijuana, similar to an alcohol Breathalyzer.

Professor of organic chemistry at UCLA Neil Garg and researchers from the UCLA start-up ElectraTect Inc. describe the method by which THC introduced, in a solution, into their laboratory-built device can be oxidized, producing an electric current whose strength indicates how much of the psychoactive compound is present. Their research was recently published in the journal Organic Letters.

According to the researchers, the availability of a Breathalyzer-like device might contribute to making roads safer given the recent legalization or decriminalization of marijuana in many states, including California. Marijuana use has been linked to dramatically increased accident risk and has been demonstrated to impair certain driving skills.

Garg and UCLA postdoctoral researcher Evan Darzi found in 2020 that removing a hydrogen molecule from the larger THC molecule allowed it to shift colors detectably. The process, called oxidation, is similar to how alcohol breath analyzers turn ethanol into an organic chemical compound through the loss of hydrogen. This oxidation results in an electric current in the majority of modern alcohol breath analyzer tools, which indicates the presence and concentration of ethanol in the breath.