The team, based at Lindfield in <?xml:namespace prefix = st1 ns = “urn:schemas-microsoft-com:office:smarttags” />Sydney, can pick up a piece of a hypodermic needle less than one millimetre long at a distance of five centimetres.
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“Conventional hand-held metal detectors couldn’t find the whole needle at half that distance,” says project leader Dr Marcel Bick, who’s been running the proof of concept experiments.
“We can even detect needles wrapped in aluminium foil, which is something a standard metal detector has lots of difficulty with,” he adds.
The team has achieved great success, even finding fragments weighing less than a milligram, because their device is no ordinary metal detector: “It’s a SQUID magnetometer,” says Dr Cathy Foley, who heads up CSIRO’s work on SQUIDs.
This type of SQUID (Superconducting Quantum Interference Device) harnesses the power of superconductors to detect very weak magnetic fields.
Cathy and her team have more than a decade’s experience applying their unique SQUID technology to geoprospecting. Their LANDTEM system is being manufactured under license by Australian company Outer Rim Developments. In 2001 the group branched out into food safety.
“We were approached by the Japanese beef industry,” Marcel explains. “Apparently they were sued by a consumer who found a piece of a needle in their steak. It turns out that it’s quite common for syringes to break off in cows when they’re being vaccinated.”
Because the food industry weren’t keen on the idea of their workers handling liquid nitrogen, the traditional coolant for SQUIDs, the team are currently working on cooling the sensor electrically.
With refinement of this technology, Cathy and her team are confident their gear could be made into the familiar paddle shape of hand-held metal detectors. “If we can find needles in meat, we can find them anywhere,” she says.
“We’ve already proved the principle, we know our SQUIDs are based on a sound technological foundation, and now we want to get them into the corrective services and airport security industries.”