PITTSBURGH (KDKA) — Researchers from the University of Pittsburgh developed a breathalyzer that can measure THC.

TrivLive.com reports that a team from Pitt’s chemistry department and school of engineering developed the device that measures how much THC — the psychoactive compound of marijuana — is in someone’s breath.

The device uses carbon tubes 100,000 times smaller than a human hair to measure THC molecules as the user breathes into the device.

The molecules bind to the nanotubes and cause a change that can be measured in their electrical properties, TribLive.com said.

The device has been patented, though it has not been commercialized yet.

It took the team three years to develop the handheld model.