WHEN you're at a bar or out with friends enjoying a beer or a vino it can sometimes be hard to keep track of how much you've had to drink and how much alcohol is in your system.
Then, if you haven't got a designated driver or you take a taxi, you run the risk of drink driving, getting picked up by the police and losing your licence or worse still, having an accident and killing of injuring yourself or another road user.
Now engineers at the University of California, San Diego have developed a wearable sensor which detects your blood alcohol level and sends the readings wirelessly to your smart phone or computer.
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.
The work, led by nanoengineering professor Joseph Wang and electrical engineering professor Patrick Mercier, both at UC San Diego, was published recently in the journal ACS Sensors.
The device 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,” Wang 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."
Blood alcohol concentration is the most accurate indicator of a person’s alcohol level, but measuring it requires pricking a finger. Breathalyzers, which are the most commonly used devices to indirectly estimate blood alcohol concentration, are non-invasive, but they can give false readouts. For example, the alcohol level detected in a person’s breath right after taking a drink would typically appear higher than that person’s actual blood alcohol concentration
The tattoo is equipped with screen-printed electrodes and a small hydrogel patch containing pilocarpine, a drug that passes through the skin and induces sweat.
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. That information is sent to the electronic circuit board as electrical signals. The data is then communicated wirelessly to a mobile device.
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 won’t be affected by the wearer’s movements, researchers said.
As a next step, the team is developing a device that could continuously monitor alcohol levels for 24 hours.