Wearable Electronics Measure How Much You’ve Had to Drink

03 August 2016

Blood–alcohol concentration is considered the most accurate indicator of a person's alcohol level, but measuring it requires pricking a finger. The most commonly used devices to track this measurement have been breathalyzers, but they can give false readouts. For example, the alcohol level detected in a person's breath right after taking a drink would typically be higher than that person's actual blood–alcohol concentration. A person could also cause a breathalyzer to detect a lower alcohol level by using mouthwash.

Recently it was proven that blood–alcohol concentration can also be estimated by measuring alcohol levels in insensible sweat—perspiration that occurs before it is perceived as moisture on the skin.

Now engineers from the University of California (UC) San Diego are running with those findings, and have developed a flexible sensor that can be worn on your body to measure blood–alcohol level from sweat.

Once the data is retrieved from the wearable sensor, it can be transmitted wirelessly to a laptop, smartphone or another mobile device.

This flexible, wearable sensor can be worn on the arm to detect alcohol level. (Image Credit: UC San Diego) This flexible, wearable sensor can be worn on the arm to detect alcohol level. (Image Credit: UC San Diego)

The engineers envision the device being worn on the skin and used by doctors and police officers for continuous, non-invasive and real-time monitoring of blood–alcohol content.

The sensor

The sensor is similar to that of a temporary tattoo, only this kind induces sweat and electrochemically detects the alcohol level. The sensor contains a portable, flexible electronic circuit board, which is connected by a magnet and can communicate the data to a mobile device via Bluetooth.

"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, nanoengineering professor at UC San Diego. "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," he added.

According to Jayoung Kim, a materials science and engineering PhD student in Wang's group and one of the paper's co-first authors, the sensor could even send alerts to your phone while you are at a party or a bar to let you know how much you have been drinking.

The alcohol sensor can accurately monitor alcohol level in sweat within 15 minutes.

"What's also innovative about this technology is that the wearer doesn't need to be exercising or sweating already. The user can put on the patch and, within a few minutes, get a reading that's well correlated to his or her blood–alcohol concentration. Such a device hasn't been available until now," said Patrick Mercier, UC San Diego engineering professor.

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.

"This device can use a Bluetooth connection, which is something a breathalyzer can't do. We've found a way to make the electronics portable and wireless, which are important for practical, real-life use," said Somayeh Imani, an electrical engineering PhD student in Mercier's lab and a co-first author on the paper.

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 and the results are sent wirelessly to a mobile device.

The team 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 a glass of red wine). The readouts accurately reflected the wearers' blood–alcohol concentrations.

The results also proved that bending and moving will not affect the results.

Now the team is developing a device that could continuously monitor alcohol levels for 24 hours.

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