New sensor upgrades artificial bomb sniffers

Researchers at Tufts University have developed a disposable plastic sensor to enhance efficiency of the artificial nose; a high-tech sniffing device they hope will improve detection of bombs and landmines.

Although experts predict that a practical device is at least five years away from actual use at airports, on battlefields and elsewhere, the researchers say their new sensor will improve the sensitivity and reliability of current prototypes.

Trained dogs – and people armed with dirt-clearing probes or metal detectors – are the current methods of choice for landmine detection. But dogs get fatigued easily, while human minesweepers are at risk of serious injury and death.

The new sensor could ultimately help save lives and reduce injuries, said David R. Walt, Ph.D., a professor of chemistry at Tufts University and lead investigator in the study.

But first, he said, the sensors must be made user-friendlier. And they must be able to solve a wider array of odour recognition problems, said Walt, who holds several patents on the new sensor technology.

His and other sensors in development tend to degrade over time, Walt said, just as the human nose looses its ability to sense and remember certain odours as people age. So the sensors need to be retrained or resensitized frequently to recognise target odours, he said.

In a process similar to replacing a dead battery with a fresh one, the new sensor is made with specially designed disposable fluorescent polymer beads. Because the beads are conditioned not to need odour-recognition training, degradation and retraining problems could be eliminated, Walt and his associates said.

Billions of the sensor beads can be made at once, providing a continuous replacement stock, according to the researchers.

To test their sensor, the researchers developed a stock of polymer beads that is sensitive to nitroaromatic compounds similar to those used in explosives. The sensor containing the initial bead-array detected the compounds with 98 percent accuracy.

When beads from the same batch were installed in a different array and tested six months later, they detected the compounds with similar accuracy (94 percent), demonstrating successful odour memory transfer from one bead array to another, they said.

Walt estimates that at least a dozen labs are working to develop a practical artificial nose technology, but acceptable accuracy still remains an elusive goal. Now about the size of a desktop computer, today’s prototypes could also be miniaturised to fit wands carried by soldiers or robots, the researcher said.

Eventually, sensors also may be able to detect diabetes and cancer on the basis of breath odours, similar to breath-analyser tests for alcohol, he concluded.

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