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Hey, Siri, am I drunk?

This wearable sensor can be worn on the arm to detect alcohol level. (COURTESY OF UNIVERSITY OF CALIFORNIA AT SAN DIEGO )

Are you sober enough to drive? The familiar way to test levels of blood alcohol (without actually drawing blood) is with breathalyzers. They are used by police trying to identify drunk drivers and in ignition-locking devices designed to prevent intoxicated people from starting a car.

But breath analysis can be distorted by such factors as ambient humidity and the use of mouthwash. Research has shown that sweat might provide a more reliably accurate medium. In an article published in ACS Sensors, a journal of the American Chemical Society, scientists from the University of California at San Diego report that they have developed a flexible, wearable and even "attractive" skin patch that detects blood alcohol in the wearer's sweat, then sends the results to a smartphone.

The researchers made the patch from temporary-tattoo paper embedded with flexible electronics. It works by delivering a small amount of pilocarpine (a drug that stimulates the secretion of sweat) to the wearer’s skin using electrical current, a process called iontophoresis. The patch electrochemically assesses the sweat’s alcohol content. And the data is transmitted to your mobile device via a Bluetooth connection. The whole process takes less than eight minutes.

Calling it “the first example of a completely wearable tattoo-based alcohol biosensor system,” the researchers say the device could easily be mass-produced and sold to law enforcement agencies, businesses and individuals.

Besides linking to ignition-lock devices in cars, they note, “such single-use printed tattoos could be used by bartenders or friends to identify patrons that become intoxicated.” They note that future systems would have to be modified to ensure privacy and data security.