Researchers Develop THC Sensor Strips To Conduct Quick Saliva-Based Sobriety Tests

A team of researchers has developed a one-time saliva swab test that detects THC in 3-5 minutes, possibly giving law enforcement a way to quickly identify drivers under the influence.

As more and more states legalize cannabis, the need for an accurate and speedy THC testing device for law enforcement is in high demand. In response, a group of researchers at the University of Texas at Dallas have engineered tetrahydrocannabinol (THC) sensor strips with an electronic reader to assess safe driving.

While other researchers are working on devices that measure THC levels via breathalyzers, these researchers have found that testing saliva is the best approach. Shalini Prasad, Ph.D., who led the study, noted that the levels of THC “are low in breath, requiring extensive, error-prone data processing to filter out effects of other compounds.”

THC is the cannabis compound widely recognized for its intoxicating effects. When consumed at certain levels, its influence on the body’s endocannabinoid system produces temporary euphoria.

The current protocol for most law enforcement involves blood tests which are accurate but also time-consuming. Some states like Texas have seriously reduced their rates of testing low-level cannabis possession due to expensive lab testing and cases rejected by overwhelmed district attorneys.

The researchers led a study to test out the accuracy of the sensor strips, which contained two electrodes, were coated with an antibody that binds THC. The testing device was found to be accurate for THC levels ranging from 100 picograms per milliliter to 100 nanograms per milliliter, easily picking up THC levels that are considered to be intoxicating.

“We used the antibody so that we could really only look at the needle in the haystack,” Prasad said.

According to the Substance Abuse and Mental Health Services Administration (SAMSHA), guidelines can be effectively screened using this platform, with .4  nanograms per milliliter serving as the oral fluid drug screening cut-off limit. The study’s authors wrote that the preliminary clinical reports suggest that a reading of anywhere above 1 to 15 nanograms of THC per milliliter of blood is considered a level of impairment.

“This is the first demonstration of a prototype device that can report both low and high concentrations of THC in a noninvasive, highly sensitive and specific manner,” Prasad says.

Now the research team is ready to take a field operable version of the device, similar in size to the glucose monitors diabetics use, outside the lab and into the streets. The new version is a portable, battery-powered device utilizing a one-time saliva swab with a THC sensor.

Not only has the device tested well for accuracy but it’s also fast. The test process is less than five minutes to complete from start to finish. Find information on the study, “Saliva test for cannabis could someday help identify impaired drivers,” here or take a closer look at the results.

THC Testing: Hemp vs. Marijuana

Another recent study out of Texas found hand-held devices were accurate in distinguishing hemp from marijuana. Hemp and marijuana are both cannabis plants, but hemp contains only trace levels of THC and is harvested for its seeds and stalks. The agricultural-based organization Texas A&M Agrilife launched a study to help farmers and law enforcement get fast and accurate results when testing hemp.

To achieve this, researchers conducted a study using a technique called Raman spectroscopy (RS). The quick and non-invasive test uses laser light to illuminate structures within materials. Researchers found that each material creates a unique scan, like a fingerprint.

Using a statistical analysis method, researchers found seven regions that differed slightly among marijuana and hemp varieties. The study’s results showed the readout in these seven regions distinguishes hemp and marijuana with 100 percent accuracy.

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