Thirsty work: scientists develop electronic skin patch to test blood alcohol levels

Many people take a chance when they drive after having a drink or two, often hoping for the best but never knowing for sure whether they’re over the limit or not. To give drivers certainty about whether they’re safe to drive after drinking alcohol, scientists have developed a flexible, wearable patch that measures a person’s blood alcohol level from their sweat, then sends the results wirelessly to a smartphone.

While ignition interlock devices — which prevent a car from starting when the driver is over the limit — exist, they are based on breath analysis, which can be affected by a number of factors including humidity, temperature and whether someone has used mouthwash before testing.

Sweat, however, can be a more reliable real-time indicator of blood alcohol content. Several transdermal sensors that measure alcohol levels in sweat have been invented, but results take up to two hours — rather defeating the purpose of the test, considering that most people would have sobered up sufficiently in that time to drive. (Or gone and had another beer while they were waiting!)

So Joseph Wang, Patrick Mercier and colleagues at the University of California, San Diego, set out to make a more rapid test. With temporary-tattoo paper, the researchers developed a patch that tests blood alcohol content non-invasively in three rapid steps. It induces sweat by delivering a small amount of the drug pilocarpine across the skin. An enzymatic reaction leads to the electrochemical detection of the alcohol content. And finally, a flexible electronic circuit board transmits the data via a Bluetooth connection to a mobile device or laptop. The steps take less than eight minutes from start to finish.

In addition to connecting to vehicles’ ignition interlock systems, the sensor could be a simple tool for bartenders, friends or law enforcement to use, the researchers say.

The monitor was described in the journal ACS Sensors.