It’s not always easy to tell whether you’ve had too much to drink.

Is it the onset of numbness in your cheeks? When you start telling your friends that Trump actually has a few decent ideas? When you sing Why Can’t We Be Friends? to your ex’s voicemail?

Some people could use someone – or something – to tell them when they are officially drunk to the point that bad decisions are probable. Like a wristband that will detect your blood alcohol.

Now, there’s something much better.

It’s also more discreet. Made with the same material as a temporary tattoo, scientists have created a wearable patch that can detect your BAC based on your sweat.

It works by delivering the drug pilocarpine to your skin to make you sweat, and a chemical reaction allows it to read your BAC. An electrical circuit then conveys that information to your phone (make sure you don’t lose it) or laptop.

It all takes less than eight minutes.

It’s been scientifically proven to work: A study published in ACS Sensors found that the device produced accurate results for nine people.

In a press release, the authors highlight that breathalyzers are not perfect because they can be influenced by humidity, temperature, and a bunch of other factors, including the use of mouth wash. The only skin sensors available before this one take two hours to get the results – which pretty much renders them pointless when it comes to the whole making bad decisions thing.

Speaking of bad decisions, the main purpose of the band is to prevent drunk driving.

UC San Diego nanoengineering professor Joseph Wang, one of the scientists behind the invention, said it could be hooked up to a car’s alcohol ignition interlocks to prevent someone with a high BAC from getting into the driver’s seat.

Of course, it also sends alerts to your smartphone to let you know when you’ve had too much to drink.

To avoid questions from curious partygoers or bar patrons, you may want to wear long sleeves.

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