Not wearable, but still a highly interesting gadged, which could be 1/10th of its price using POET, all on one chip:
https://www.kickstarter.com/projects/903107259/scio-your-sixth-sense-a-pocket-molecular-sensor-fo
http://www.consumerphysics.com/
I hope to get one of those mid of next year - but with POET such a "toy" should cost much less - with smaller dimensions (all on one chip) it could even fit in a smartphone. Could then be the next big thing!!!