Sniff of success

A UNSW invention could revolutionise the front-line of airport security, writes Frank Walker.

Charles Harb doesn’t want to put bomb sniffer dogs out of a job, but a laser device developed at UNSW Canberra capable of detecting tiny traces of explosive vapour might just do that.

The machine is “about 100 times more sensitive and … 100 times faster than any other detection device”, according to Associate Professor Harb, from the School of Electrical Engineering and Information Technology. 

A prototype of the device – a pulsed, quantum laser-based, cavity ringdown spectrometer – is now being tested at the US Government’s Los Alamos National Laboratory in New Mexico.

The device could be positioned to “sniff” bags travelling along a conveyor belt and instantly alert security personnel if it detects explosive vapours coming from a passing suitcase.

Similarly, it could be used at airport security checkpoints where people walk through arches designed to detect metal, knives and guns. A hose attached to the arch would pipe air to the device that’s the size of a desktop printer and could detect a person carrying explosives.

Ultimately it could replace sniffer dogs and those intrusive and unpopular airport security checks such as full body scans and pat downs as well as the inconvenience of having to remove shoes, jackets and belts.

Other devices can detect vapour from explosives, but they are nowhere near as fast, says Harb. The reason is as simple as an old magic trick – it’s done with mirrors.

“Using mirrors we got the laser to repeatedly pass through the vapour in a figure-of-eight path. That gave us a much more accurate measurement and we were able to detect the vapour components of TNT such as acetone, nitrobenzene and nitromethane.

“We can measure these components of TNT very clearly – down to the tiny sub-millitorr pressures, in other words in the parts per billion range in atmosphere.”

After further testing, the device should be able to be calibrated to detect the unique signatures of other substances and different types of explosives. Harb thinks it will take up to two years of testing before it is ready for commercial use.

Harb and his team began work on the laser “sniffer” in 2005 after they were approached by the Australian Federal Police. The police were looking for a machine that could help them with forensic investigations and accurately detect residues of explosives at crime scenes.

“Sniffer dogs do a great job,” says Harb. “But they can’t work 24/7. They need breaks. They can only do spot checks on luggage at airports. Also we can’t tell exactly what the dog has reacted to. Police wanted a machine that could work non-stop, identify the actual type of explosive and check every suitcase passing on a conveyor belt.”

In 2009, the Australian Research Council provided a grant. Harb developed the device, supported by Scientia Professor Ian Petersen and research associates Dr Toby Boyson and Dr Abhijit Kallapur.

Harb also worked with specialists at Loyola University in New Orleans and Los Alamos National Laboratory.

This year Harb had a paper on the breakthrough device published in the Optics Express journal of the Optical Society of America. In September the work was a finalist in the Advanced Innovation (Partnership) division of the UNSW Innovation Awards.

Although the prime purpose of the machine is to detect explosives, Harb says there are other possibilities.

“I hope one day it could be used in medicine. We’ve heard of dogs that can sniff out cancer. We don’t know what they smell, but once we do, there’s no reason why we couldn’t set the machine to detect those vapours as well.”