Researchers sniff out secrets of the nose

Artificial smelling device being developed in labs


PASADENA, Calif. -- Nate Lewis earned his scientific name coaxing chemical leaves to pull energy from sunlight. A decade ago, he led a team that handily debunked the myth of cold fusion. Now, Lewis is onto what may be his most difficult project: He's building an artificial nose.

The restless 43-year-old chemist started sniffing at the project because it was uncharted territory. Of all the human faculties, smell remains the least studied and most misunderstood.

Undaunted, Lewis is busy untangling the chemical riddle of smell -- an achievement that could have large economic and social consequences.

His goal is to create artificial noses so small, so sensitive and so cheap -- less than $1 a nose -- that they will be as ubiquitous as computer chips.

Lewis envisions noses in your car, sniffing for failing brake fluid or leaking Freon. He sees them in your house, sniffing for radon gas or carbon monoxide. He sees them in your refrigerator, complaining about rotting food, and in your doctor's office, diagnosing ulcers, diabetes and cancer from a single breath.

In his crowded lab at California Institute of Technology, dime-sized "noselets" blink red and green LED lights as they sniff, crawling robo-noses twist and turn their way into streams of wind, and a bookcase-sized collection of glass tubes dubbed "Pinocchio" can identify the smells of roses, wine, garlic and rotting fish.

All this technology is focused on questions that can seem better suited to sonnets than to laboratory benches.

Odd as their scientific passion may seem, Lewis and his Cal Tech team are not alone in their quest. Lewis' group created a basic nose in the early 1990s before learning that a British group had been first to the invention.

Now a number of labs are working on rival noses -- and a few models are on the market.

But those commercial artificial noses aren't sensitive enough for many real-world sniffing jobs. And with price tags that reach $100,000, the bulky machines are not in widespread use. Lewis hopes to change all that.

As it happens, smelling is big business. Legions of human noses are gainfully employed sniffing out rotten food, off-notes in perfume, luxury car leather and -- in deodorant tests -- other people's armpits.

But because human noses tire quickly and aren't sensitive to all odors, people in the sniffing business dream of portable, inexpensive artificial noses that could do everything from throw truffle-hunting pigs out of work to pick out an irresistible perfume.

NASA wants a few good noses to sift through stinky space air for health hazards, and the agency sent one of Lewis' protonoses into orbit with John Glenn.

The military is paying $25 million -- a chunk of that to Lewis -- to develop an artificial dog nose sensitive enough to sniff out the faint chemical traces of land mines, which maim thousands each year.

But before noses can change the world, there's a little chemistry to be done.

Lewis' group uses an array of cheap industrial plastics -- there are many -- to create a wide range of sensors that will detect many different kinds of chemicals.

Not only are these working-class plastics cheaper, but they're also more rugged and aren't put off by changing temperature and humidity levels like their more rarefied cousins.

Early noses with about 20 sensors have proved they can detect myriad odors at about the sensitivity of the human nose -- in the range of parts per billion for some smells.

With the nearly limitless variety of sensors now available, Lewis is trying to pack 10,000 sensors of different types onto a chip. That nose, small enough to fit into one of Jimmy Durante's nostrils, should be able to surpass human sensory capabilities for many odors.

Once created, it could be mass-produced quite cheaply. A commercial arm of Lewis' research effort, Cyrano Sciences, is trying to do just that.

A hand-held nose device could be available this year. More sensitive noses and noses on chips are still a few years off.

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