L’Oreal and John Rogers built a sticker to measure skin hydration
 

The fruitful partnership between cosmetics giant L'Oreal and wearable pioneer Professor John Rogers has produced a new sensor for 2019. My Skin Track pH by La Roche-Posay is a wearable sensor, smaller than a Band Aid, that monitors your skin's hydrat...

https://www.engadget.com/2019/01/06/...k-ph-wearable/