Packing four sensors into a housing smaller than an iPod Nano, the CORE 2 will be the smallest wearable multi-sensor device of its kind as well as the first to offer a choice of interchangeable jewelry- like faceplates, straps and cuffs for a fashion look.

ENGADGET: BodyMedia's CORE 2 armband tracks your health, or lack thereof

The filing also suggests that the device could house an end-detection sensor, allowing the wearable to configure itself to each user, regardless of differing wrist measurements, and deactivate sections of the flexible display that aren't on show.

ENGADGET

Wearable 3D body motion tracking is enabling the next wave of innovation in cloud-connected wearable sports, fitness, healthcare and gaming sensor accessories for smartphones.

ENGADGET: Xsens teases wearable 3D body sensors that won't cost, will track an arm and a leg (video)

Fitbit, which helped pioneer this kind of wearable tech, is also back with Flex, which distinguishes itself by letting users swap its sensor unit from one wristband to another to co-ordinate with their clothes.

BBC: CES 2013: Health and safety technology booms