"It resembles a temporary tattoo, but is actually a biosensor patch that is embedded with several flexible wireless components," Seila Selimovic, the director of the program that helped develop this tech, told Science Daily. "One component releases a chemical that stimulates perspiration on the skin below the patch. Another component senses changes in the electrical current flowing through the generated sweat, which measures alcohol levels and sends them to the user's cell phone."
The real key here is that the measurement takes just minutes, not hours. "Measuring alcohol in sweat has been attempted before, but those technologies took 2-3 hours to measure alcohol levels," said Patrick Mercier, one of the senior authors on the article. "Our patch sends alcohol levels to your smartphone in just 8 minutes, making real-time alcohol monitoring possible, practical, and personal."
Efforts to create wearables and at-home breathalyzers that effectively measure alcohol levels have been mixed. The fact that this particular device is discreet, works quickly and appears to be accurate bodes very well for the future of this product.