THC spit test: Stanford researchers working on marijuana DUI tool

STANFORD, Calif. (KTVU) - Law enforcement officers may soon have a new tool to help keep people from driving under the influence of marijuana. Stanford researchers say they’re close to perfecting a roadside test for driving while high.

“A lot of people are driving under the influence of marijuana, but it cannot be really determined,” says Shan Wang, Ph.D and Stanford University engineer.

Dr. Wang leads a team of graduate students who may have the solution, generated from saliva samples.

Team leader Tyler Shultz used a decade of cancer research as a starting point.

The problem is getting the sensor to lock onto tiny THC molecules in marijuana.

Shultz uses a beach ball analogy. “What we’re trying to do is have two hands grab the beach ball, except THC is so small that one hand grabs it, there’s nowhere else for the other hand to go,”

The solution— design special magnetized nano-particles that latch onto THC. Then introduce a saliva sample tainted with marijuana.

“So when the nanoparticle comes near the sensor, we detect a large signal,” says Dr. Wang. “We can deduce how many molecules of marijuana are in the saliva.”

Putting the heady science aside, there’s a prototype gizmo in the works.

Ph.D. student Elaine Ng is designing the device to be more user-friendly for law enforcement.

She says she’s trying to figure how the police officer would interact with the device and how to make the process simpler for the officers to do these roadside tests.

Researchers have already developed a breathalyzer for marijuana, but they say it’s not that accurate. The saliva test, however, can show nanograms of marijuana in your system and show those results in just minutes.

Clinical trials are on the horizon, but Dr. Wang is still filled with wonderment at how this cutting-edge technology could ultimately save lives.