L’Oreal and John Rogers built a thumbnail-sized UV sensor
 

L'Oreal is not a name that you'd normally associate with CES, but the cosmetics giant is now a regular exhibitor at the show. This year, the company is demonstrating a thumbnail-worn smart device that's less than two millimeters thick. UV Sense is a...

https://www.engadget.com/2018/01/07/...zed-uv-sensor/