Smells are intelligent sensors' last frontier

Phones or watches may be smart enough to detect sound, light, motion, touch, direction, acceleration and even the weather, but they can't smell.

That's created a technology bottleneck that companies have spent more than a decade trying to fill. Most have failed.

A powerful portable electronic nose, said Redg Snodgrass, a venture capitalist funding hardware start-ups, would open up new horizons for health, food, personal hygiene and even security.