Artificial Nose Could Sniff Out Bombs, Cancer

Anne Minard
for National Geographic News
October 6, 2008
A new discovery could lead to the world's first "smell-based biosensing device"—aka an artificial nose.

MIT researchers can now mass-produce the receptors humans use to detect odors. The finding has implications for law enforcement, medicine and the military.

Drug- and explosive-sniffing dogs could become obsolete, for example.

Certain cancers—lung, bladder, skin—that produce distinctive odors in their early stages could be identified using such a device, Shuguang Zhang, associate director of MIT's Center for Biomedical Engineering and senior author of the study, said in a statement.

The Defense Advanced Research Projects Agency (DARPA)—the research branch of the U.S. Department of Defense—has committed to funding a large collaborative project, dubbed RealNose, with Zhang at the helm.

(Related: "Robo-Nose: Hi-Tech Bomb Sniffer Smells Like a Dog" [October 1, 2003].)

Smell Cells

Olfactory receptors, the proteins responsible for the sense of smell, are notoriously difficult to isolate in the lab.

Until now, researchers have had difficulty producing them in quantities large enough to be useful, as the proteins lose their structure when exposed to water.

The research team spent several years isolating and purifying receptor proteins using ingredients such as wheat germ and detergent. Now the scientists can grow large amounts, enough to use in research and industry.

Luca Turin penned the 2006 book The Secret of Scent: Adventures in Perfume and the Science of Smell and is a biophysicist at Flexitral, a Virginia scent and flavor lab. He called the study a "landmark piece of work."

"Shuguang's group has overcome great technical difficulties and is now in a position to produce milligram quantities of pure olfactory receptors," he said. "Once you can do that, all manner of avenues open.

"You can use the receptors to build novel sensor devices, and that's the future," he said.

The study appeared in last week's issue of the Proceedings of the National Academy of Sciences.

Nose Knowledge

Scientists still don't know exactly how the receptors function or how odors are interpreted in the brain.

"Smell is perhaps one of the oldest and most primitive senses, but nobody really understands how it works. It still remains a tantalizing enigma," said MIT's Zhang.

Brian Cook, who earned his Ph.D. working on the project, said he's most excited about learning about smell at the molecular level.

"No one is really sure how these receptors interact with and recognize specific odor molecules," he said. "There has been much controversy regarding this subject, and several competing theories have been battling each other for decades."

Isolating the olfactory proteins is the first step, he said, but the road to artificial noses will require much more work.

© 1996-2008 National Geographic Society. All rights reserved.