Scientists have developed a flexible wearable skin sensor that can accurately and quickly measure a person's blood alcohol level from sweat and transmit the data wirelessly to a laptop or smartphone. The device can be worn on the skin and could be used by doctors and police officers for continuous, non-invasive and real-time monitoring of blood alcohol content. "Lots of accidents on the road are caused by drunk driving. This technology provides an accurate, convenient and quick way to monitor alcohol consumption to help prevent people from driving while intoxicated," said Joseph Wang, professor at University of California (UC), San Diego in the US. The device consists of a temporary tattoo - which sticks to the skin, induces sweat and electrochemically detects the alcohol level - and a portable flexible electronic circuit board, which is connected to the tattoo by a magnet and can communicate the information to a mobile device via Bluetooth, researchers said. "The device could be integrated with a car's alcohol ignition interlocks, or friends could use it to check up on each other before handing over the car keys," said Wang. "When you are out at a party or at a bar, this sensor could send alerts to your phone to let you know how much you have been drinking," said Jayoung Kim from UC San Diego. Researchers developed this alcohol sensor that is wearable, portable and could accurately monitor alcohol level in sweat within 15 minutes. "What is also innovative about this technology is that the wearer does not need to be exercising or sweating already," said Patrick Mercier from UC San Diego. "The user can put on the patch and within a few minutes get a reading that is well correlated to his or her blood alcohol concentration. Such a device has not been available until now," said Mercier. "This device can use a Bluetooth connection, which is something a breathalyser cannot do. We have found a way to make the electronics portable and wireless, which are important for practical, real-life use," added Somayeh Imani from UC San Diego. The tattoo works first by releasing pilocarpine to induce sweat. Then, the sweat comes into contact with an electrode coated with alcohol oxidase, an enzyme that selectively reacts with alcohol to generate hydrogen peroxide, which is electrochemically detected, researchers said. That information is sent to the electronic circuit board as electrical signals. The data is communicated wirelessly to a mobile device, they said. Researchers tested the alcohol sensor on nine healthy volunteers who wore the tattoo on their arms before and after consuming an alcoholic beverage (either a bottle of beer or glass of red wine). The readouts accurately reflected the wearers' blood alcohol concentrations. The device also gave accurate readouts even after repeated bending and shaking. This shows that the sensor will not be affected by the wearer's movements, researchers said. The findings were published in the journal ACS Sensors.