Inventors John Kauer and Joel White fit Alan with the electronic nose.

The canine nose is a remarkable organ. About one hundred times more sensitive than a human nose, it can sniff out illegal drugs, track fugitives - even find rot spots in wooden structures. But to bring out a dog's natural smelling ability requires a talented human trainer, like former Secret Service agent Ed Hawkinson who used explosive-sniffing dogs to guard the President. Today, he trains Labradors to detect weapons in schools.

In "The Dog Nose Knows," Alan meets John Kauer and Joel White, both neuroscientists at Tufts University in Massachusetts. Kauer and White have built a sniffing device modeled on a dog's nose that they hope will help safely detect the estimated 50 to 100 million landmines buried around the world. Real dogs have had some success finding landmines, but it's not clear how they do it, and, of course, even a single error could be deadly.

The "nose" uses chemical sensors to identify the DNT in this concrete block.

The new device consists of a computer, a battery-pack and a hose-like "sniffer" that draws in odor molecules. When the inhaled molecules combine with chemical sensors inside the contraption, the sensors change colors, creating a signature visual pattern for each aroma. Light sensors "read" this pattern to determine the identity of the odor.

In a test run with Alan, the virtual nose easily detects the difference between plain air, non-explosive DNT and methanol. The machine can smell odors at concentrations as low as 10-20 parts per billion, but the scientists hope to get it down to one part per billion. Then it would rival a real dog's nose, and help authorities find those millions of unexploded mines.

For more on this topic, see the web feature:
The Real Price of Landmines
What the Nose Knows
What's New with the Artificial Nose?