While many of his colleagues work on robots that can see, Andy Russell, an electrical engineer at Monash University in Australia, realized that a sense of smell could be helpful to robots as well, allowing them to navigate along scent trails like ants leading comrades to food.
After a lead ant marks the path, a follower picks out the aromatic marker with its antennae. When the left antenna hits the trail, the ant turns until the right antenna picks it up, and so forth. Russell's robots follow paths using the same method.
He imagines that an odor detector could tell a troop of robots where they have been, useful for sweeping for land mines or mopping a floor. And a robotic explorer could blaze a trail for cheaper, simpler followers--for mineral prospecting or even planetary exploration.