The age-old excuse of not knowing how many drinks you've had might soon be a thing of the past, thanks to a temporary electronic tattoo that can measure alcohol levels in the body.

An electronic sensor similar to a stick-on tattoo allows users to check their own sobriety. The device, created by a research group from University of California San Diego (UCSD), is a tattoo with a small electronic board magnetically attached to it that sticks on the user’s skin. It releases a drug called pilocarpine, generating sweat on the skin’s surface. The sensors in the tattoo measure the alcohol content in the sweat

It releases a drug called pilocarpine, generating sweat on the skin’s surface. The sensors in the tattoo measure the alcohol content in the sweat, and results are then sent to the user’s mobile phone via Bluetooth.

The stick-on device can measure alcohol levels in your body. Photo: UCSD/ACS Sensors

Breathalysers, currently the most commonly used devices to measure drunkenness, can give false readouts. The most reliable results can be found by measuring the blood alcohol concentration (BAC), but that requires injecting a finger. Researchers at UCSD wanted to develop a non-invasive method to measure alcohol that is as reliable as the BAC.

“We developed a new tattoo-based wearable alcohol sensor that enables real-time monitoring of blood alcohol level, overcoming limitations of conventional non-invasive alcohol sensors,” Jayoung Kim, a co-author and PhD student at UCSD.

The device was tested by a group of nine healthy volunteers, who wore the tattoo on their arms before and after consuming alcohol.

One factor that bodes well for the tattoo's success is its low cost: electrodes used in the tattoo's sensors were made using a screen-printing technique that costs less than $1, according to Kim.

The same technique could also be used to monitor glucose and lactase levels. The researchers now hope to personalise the tattoos and to develop a smartphone application that is more user-friendly.

The study results were published in ACS Sensors.