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Wrist Wearable Wins Alcohol Biosensor Contest

U.S. federal agency awards $200,000 to BACtrack Skyn wearable alcohol sensor

3 min read

Bearded man with beer in hand and BACtrack alcohol biosensor on wrist.
Jon Hicks/Getty Images

The U.S. government wants to speed up development of wearable alcohol sensors; in that vein, today it announced the winners of a contest intended to stimulate innovation. The U.S. National Institute on Alcohol Abuse and Alcoholism (NIAAA) awarded a $200,000 first prize to San Francisco–based BACtrack, and a $100,000 second prize to Santa Barbara, California–based Milo Sensors. Both groups submitted prototypes of wrist wearables that detect traces of alcohol diffusing through the skin. 

The competition, called the Wearable Alcohol Biosensor Challenge, called for  a discreet wearable device capable of continuously measuring alcohol levels in near real-time. “The field of alcohol biosensors has been plateaued for at least ten years,” says Kathy Jung, a program director at the NIAAA. “We wanted to attract new people to the field.” 

Existing alcohol biosensors are used primarily by the criminal justice system to monitor people with a proclivity for driving under the influence. Lindsay Lohan and other celebrities have famously posed for the paparazzi and trudged the red carpet wearing SCRAM and other ankle monitors. The devices detect transdermal alcohol concentration, or TAC, a measurement of alcohol in sweat or vapor from the skin that reflects, on a delay, the amount of alcohol in the blood. 

The detection delay from these bulky bracelets is significant—often hours. And they only take measurements every 30 minutes. Better, less ball-and-chain-like devices are needed, particularly for research and alcohol treatment purposes, says Jung. “We want something that is removable and that people are willing to wear, rather than this thing with so much stigma,” she says. Such a device could be useful for the general public too: mainly for people who want to better monitor their health and ability to drive. 

imgPhoto: BACtrack

The winning entry, called the BACtrack Skyn, miniaturizes transdermal sensor technology so that it can be integrated into a Fitbit-like wearable. Unlike court-ordered ankle monitors, it takes alcohol readings once per second.

The system sends the data wirelessly to a phone app that graphs changes in the volume of alcohol over time. “It could vibrate or send you a text message” when your alcohol level is getting too high, says Keith Nothacker, CEO of BACtrack. “It could notify a number of other people—family, clinicians or it could call an Uber for you.”

BACtrack’s device features an electrochemical sensor with three electrodes, and operates like a fuel cell. As ethyl alcohol, or ethanol, permeates the skin it is oxidized, generating an electric current that is proportional to the number of ethanol molecules the device picks up. The system reads the current and calibrates it to reflect an estimate of blood alcohol concentration, or BAC. 

NIAAA judged the contestants’ prototypes based on accuracy, frequency of readings, marketability, and other criteria. Testing the prototypes required alcohol consumption, of course. Volunteers came to the Institute’s lab and hung out while an IV dripped alcohol into their veins. “The person reads or watches TV and they can push a button to take in more alcohol whenever the mood strikes them,” says Jung. 

The volunteers’ alcohol levels were estimated by the Institute’s well-refined algorithms, backed with breathalyzer tests, and graphed over two hours. The wearable prototypes took measurements at the same time, and the graphs of the two were compared. “What we liked about BACtrack was how nicely their data paralleled the breathalyzer data,” says Jung. “And it’s ready to wear.”  

The second place team, Milo, also used a miniaturized transdermal technology for the wrist, but did not disclose the details. “The thing we liked about Milo is that they are a start-up team; they were college kids—and they  developed what they had with $15,000,” says Jung. “This is the kind of innovation and energy that we really need. Their device did detect alcohol—although not as beautifully as the winner’s did. But it shows very good promise.” 

There’s still room for improvement. It often takes about a half hour for alcohol to start percolating through the skin enough for BACtrack’s device to detect it. And the wearable’s estimate of BAC needs to be perfected, Jung says. The NIAAA plans to fund more alcohol biosensor projects in the hope of finding one that delivers a true and immediate measure of blood alcohol, she says.

BACtrack plans to commercialize the Skyn some time in 2016, says Nothacker. The company has been around since 2001, and is best known for its consumer-oriented breathalyzers, which have been used for everything from drunk driving prevention to determining which football fans and red carpet celebrities are the drunkest. 

That’s a sensitive issue. Wearables make data-based collegiate beer battles that much easier to track. “You hear disturbing stories of college students or young adults using the breathalyzers to say ‘I’m more drunk than you,’ and see who can out-do each other,” says Jung. 

But Nothacker says breathalyzers and trackers don’t promote that kind of behavior. “Any time people are talking about BAC, that’s a positive thing. That’s awarenessIf people are going to get drunk, they’re going to get drunk. They have been for centuries. We think it’s better for them to have the information.”

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