Wearables get smaller and smarter

L'Oreal's UV Sense, a wearable electronic UV sensor affixed to a user's thumbnail. It measures individual UV exposure and is designed to be worn for up to two weeks. (L'Oreal)

First there were fitness wearables. Then the focus turned to fashionable wearables. The latest evolution, seen throughout this week's CES in Las Vegas: more functional, futuristic – and sometimes far-fetched – wearables. 

Wrist-worn wearables were a huge hit at the trade show four years ago, as tech makers showed off fitness trackers and smartwatches that monitored steps taken, stairs climbed and calories burned. The technology went on to become enormously popular among consumers, with an estimated 310 million wearable devices sold worldwide last year.