The advantage in having a dog as a bomb-detection tool is that it is very, very good at sniffing out explosives.
The disadvantage is that, compared with electronic alternatives, it is also very good at getting distracted by sausages and then needing a wee.
Scientists in the US believe that they have found a happy compromise by designing an electronic nose that draws its inspiration from a dog; a device that improves performance tenfold without ever needing a treat or a good scratch.
They realised that one of the key abilities of a dog is not just detecting smells, but also drawing them into its nose. Some electronic chemical detectors do have suction pumps, but none has the sampling capability of a sniff.
“Dogs are still the gold standard in trace chemical detection,” Matthew Staymates, from the National Institute of Standards and Technology, said. “When we talk about detecting things like contraband we like to break it into two components. One is the detector part. Lots of work has been done into understanding what goes on in a dog’s nose. We are good at making detectors.
“The other part is sampling — how you get the molecule you are looking for to a detector. This is overlooked.”
He explains in the Scientific Reports journal that a dog’s sniff is no simple thing. “A canine sniff generally consists of an inspiration followed by an expiration that is cyclically repeated at a frequency of approximately 5Hz.”
Five times every second, dogs violently disrupt the air flow around their nose, breathing in and out rapidly to pull in vapour from all around. The crucial part is the exhalation: when the dog blows out it directs the flow behind it, sucking in more air from ahead.
This creates a “jet-assisted fluid entrainment [which] increases the aerodynamic reach of the dog’s nose, drawing vapour-laden air toward the nostrils that would otherwise be inaccessible.”
By 3D-printing a dog’s nose and mimicking this behaviour, he and his colleagues created a device that produced a huge improvement over its competitors — proving the efficacy of the canine nose.
Mr Staymates conceded that it still could not match the sniffing ability of a cocker spaniel in full flow — but insisted that the technology had enormous value nonetheless.
“I have lots of friends who are dog owners,” he said. “My understanding is dogs are expensive to maintain and train, and they get tired and cranky, just as we do.
“A detection device you plug into the wall doesn’t get tired and cranky.”