Stanford researchers have developed roadside saliva test for marijuana

‘Potalyzer’, also known as marijuana roadside saliva test, has been developed by the scientists from Stanford. It is based on magnetic nanotechnology that initially proved to be an effective way of screening cancer. This invention may be the first successful attempt of creating a roadside test for weed. 


‘Potalyzer’ can be compared to breathalyzers in terms of effectiveness. The police that are currently testing the innovative method say no other tool on the market is known to be as quick and precise in diagnosing the driver’s intoxication with marijuana. Laboratory urine and blood tests are not very helpful to police officers as these tests focus on detecting THC, marijuana’s most powerful agent. ‘Potalyzer’ is very practical and can measure both the presence and the concentration of THC in saliva. 

Stanford researchers, including the team leader Shan Wang, professor of materials science and engineering and of electrical engineering, managed to use magnetic biosensors as part of a mobile device detecting THC molecules contained in saliva. All the officer needs to get the result is collecting saliva samples with a cotton swab and analyzing the sample with the help of a laptop or a smartphone. The test takes less than three minutes. 

Scientists claim analyzing THC from saliva is more representative than taking a blood or urine test. The new procedure is less invasive and more informative. It seems challenging, however, when it comes to detecting very little concentrations of THC through spit tests. The smallest allowed amount of THC not being set in many states, while those that did it have agreed upon 0 to 5 nanograms per milliliter of blood. 

Wang’s method is applicable when THC concentration is within 0-50 nanograms per unit of saliva. As found by previous studies, having from 2 to 25 nanograms per milliliter can already be called an impairment that is too much for the driver. Wang’s ‘Potalyzer’ is fully functional within this range. 

The user-friendly form factor for the invention is being worked at currently. As soon as ‘Potalyzer’ is tested and approved by regulators, the police will be allowed to use it. It also needs strict limits for THC concentration in a driver’s spit sample to be set by all state’s laws before the device can be of any help in law enforcement.