CU Boulder nanoengineer creates "smart tattoo" using ink that changes with light

How it works: The little blue dot in his arm turns "on'' when exposed to ultraviolet light, while light from the sun or a flashlight turns it "off."

• The ink is made of particles of dye encased in beads of Plexiglas, which is similar to the material used for lip fillers.

Driving the news: He's now turned his experiment into a company and plans on releasing its first product, Magic Ink, early next year, according to KFF Health News.

Why it matters: It could have broader applications beyond novelty, since Bruns and his colleague have made an ink that detects exposure to gamma radiation and another that shows up when it's time to put sunscreen on.

What they're saying: "You can go to court and turn it off, and then go to the party and turn it on. And then go to Grandma's house and turn it off," Bruns told KFF Health News.

Of note: Bruns has teamed up with Keith "Bang Bang" McCurdy, a tattoo artist known for working with celebrities like Rihanna and Miley Cyrus, to launch the company.