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Electronic nose sniffs out trouble
By Dan Gaffney
December 12, 2008
By Dan Gaffney
December 12, 2008
Graffiti artists risk being sniffed out by an "electronic nose" that can detect paint, tip off security officers, and prevent the high cost of graffiti vandalism. Developed by UNSW and University of Sydney scientists, e-nose technology has drawn interest from NSW rail corporations and has potential uses in emissions monitoring and the security industry.
The device does its job by comparing its response to detected aerosol molecules and a "bank" of smells programmed into its database. No bigger than a tissue box, it monitors air continuously and can identify a plume of airborne molecules from a four-second spray of paint up to 45 metres away. A bank of the devices could be installed to protect large sites such as wharves, rail yards and warehouses because they can be easily camouflaged, or hidden from view.
It takes an average of 17 minutes to deface a railway carriage abase, according to one the technology's developers, Dr Graham Bell. "That's more than enough time to detect the aerosol paint, send a wireless message, and scramble security officers to thwart the attack," he says.
The device has significant advantages over traditional security measures - it's much cheaper than a 24-hour security team and it captures data that chemically "fingerprints" the paint, which could be useful for securing convictions in court.
The electronic nose is a deceptively simple device. It contains half a dozen sensors that can each respond to the reaction of substances with oxygen by a change in electrical resistance. It is the pattern of these responses that creates a 'fingerprint' of the smell.
"Each sensor has a slightly different composition, which makes their responses to a molecule different", explains Brynn Hibbert, a co-inventor of the device. "So when a smelly molecule comes along all the sensors respond, but to different extents depending on the molecules and their concentrations. Oxygen from the air restores the surface when the smelly molecules go away, so we have real-time monitoring."
The e-nose could supplement sniffer dogs and other security measures at borders and checkpoints, according Dr Bell. "Security dogs are very mobile but the e-nose doesn't go off duty for food or rest breaks, and it doesn't get bad moods if its handler is away or on holidays. Also, sniffer dogs have been known to fail.
For example, a dog could be standing next to a bag of contraband material and be unaware that it's there, because it hasn't been trained to sniff at that level of concentration. Further, sniffer dogs are trained to sniff one particular thing but the e-nose can be programmed to sniff hundreds of odours very quickly."
Graham Bell is a conjoint associate professor at the UNSW School of Medical Sciences and Managing Director of E-Nose Pty Ltd. E-Nose provides sensory research services to the food and allied industries on matters of smell and taste in humans and animals.
Brynn Hibbert is UNSW Professor of Analytical Chemistry and heads the Chemometrics And Metrology Group.
E-Nose Pty Ltd http://www.chem
Media contact: Dan Gaffney - 0411 156 015
