WASHINGTON (dpa-AFX) - Researchers from the University of Pittsburgh have developed a breathalyzer that can measure if a person is driving a vehicle under the influence of marijuana. The invention is a significant development that comes as more states in the U.S. legalize recreational and medical marijuana.
While police have breathalyzers to detect the presence of alcohol, they do not have a device to detect if a driver is under the influence of marijuana.
Current drug testing methods rely on blood, urine or hair samples. These tests only reveal if a user has recently inhaled the drug and not whether he is currently under its influence.
A team from the University of Pittsburgh's Department of Chemistry and the Swanson School of Engineering developed a breathalyzer device that can measure the amount of tetrahydrocannabinol or THC in the user's breath. THC is the psychoactive compound in marijuana that gives users a high.
The device was developed using carbon nanotubes, tiny tubes of carbon that are 100,000 times smaller than a human hair. When a user breathes into the device, the THC molecule and other molecules in the breath bind to the surface of the nanotubes and change their electrical properties that can be measured.
Nanotechnology sensors can detect THC at levels comparable to, or even better than mass spectrometry, which is considered the gold standard for THC detection.
The paper detailing this research, 'Tetrahydrocannabinol (THC) Detection using Semiconductor-enriched Single-Walled Carbon Nanotube Chemiresistors,' was published in the journal ACS Sensors.
'The semiconductor carbon nanotubes that we are using weren't available even a few years ago. 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,' said Sean Hwang, lead author on the paper and a doctoral candidate in chemistry at Pitt.
The prototype resembles a breathalyzer for alcohol, with a plastic casing, protruding mouthpiece, and digital display.
The researchers said they will continue to test the prototype, and hope to soon move it to manufacturing and make it available for commercial use.
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