SciTech Daily, the tattoos are temporary and are placed by taking the OLED tattoo paper and pressing it against the skin with a wet cloth. The smart tattoos are easily removed by scrubbing with soap and water.

While these tattoos will undeniably make for some great Halloween costumes and cosplay, scientists point to more practical uses that can greatly help people. When combined with other “tattoo electronics,” athletes can use light-emitting tattoos to detect when they are dehydrated or when they’re about to get sunburnt.

“The tattooable OLEDs that we have demonstrated for the first time can be made at scale and very cheaply,” Professor Franco Cacialli, the senior author of the paper, said. “They can be combined with other forms of tattoo electronics for a very wide range of possible uses.”

Cacialli points to medical uses for smart tattoos that can make breakthroughs in the fight against cancer.

“In healthcare, they could emit light when there is a change in a patient’s condition – or, if the tattoo was turned the other way into the skin, they could potentially be combined with light-sensitive therapies to target cancer cells, for instance,” Cacialli said.

The OLED tattoos are approximately 2.3 micrometers thick or, as SciFi Daily puts it, 1/400 of a millimeter. The researchers successfully used the technology to make a green light glow on glass, paper, plastic, and an orange. The tattoos can also be placed on fruit or food packaging to detect when they are expired, according to SciTech Daily.

According to IGN