How L’Oreal Built a UV-Measuring Temporary Tattoo

WHEN L’OREAL PITCHES you on its new wearable, you envision a Wi-Fi-connected makeup compact or some sort of skin-toning helmet. Or maybe a lipstick tube that’s also a USB stick. What you don’t envision is a sticker—a temporary tattoo with teeny, tiny circuits inside.

The beauty company has its own tech incubator, run by L’Oreal tech guru Guive Balooch. His team partnered with sensor-maker MC10 and design firm PCH to create a wearable called the My UV Patch. It attaches directly to your skin and measures UV exposure, relaying the information back to an app. You access the app by scanning the sticker (using NFC or your phone’s camera), which you obviously want to put somewhere the sun will indeed shine. The app gives you information about your UV exposure, using a pattern of blocks of color made of photosensitive dyes that measure your baseline skin tone and change colors when you’re out in the sun, depending on its strength.

You apply it like any other sticker, except this one hangs around a little longer—three to five days, usually. A few activity trackers and even more specific wearables measure UV to tell people whether they’re getting too much or too little sunlight, but not a lot of people are going to wear a Fitbit for UV health. A temporary sticker? Maybe. The app is cute and easy to use, and skin health is an important thing to monitor. But by far what’s most interesting about the product is that it’s one of the first flexible, skin-adhesive wearables that has a shot at a mainstream market.