Interesting article from Defense Technology International (Volume 4, Issue 4) describing advances in olfactory surveillance.

Sniff And Tell, Science Watch, 1 April 2010 by Michael Dumiak

Nanoparticle gel and integrative data are the latest tools being tested for security in military and civilian infrastructures. They hold the potential of snaring everyday criminals such as drug smugglers and terrorists like the foiled underwear bomber Umar Farouk Abdulmutallab.

Detection equipment is getting smaller, more integrated and easier to use, says Steven Bell, a physical chemist at Queens University of Belfast, Northern Ireland. Bell produced a prototype gel swab tester that relies on handheld Raman spectrometers to detect trace elements of explosives, drugs, or chemical and biological agents.

Bells background is in Raman spectroscopy, an electromagnetic spectrum-scanning technique that focuses a laser onto a sample. The scanner collects the laser light scattering off the sample surface. Some of this light undergoes a change in energy state. The pattern of energy change identifies the chemical bonding within the sample.

Raman spectroscopy is an old science. Recent advances in optoelectronics, Bell says, such as small lasers, small spectrometers, and high-efficiency detectors, make using it in the field more practical. Its gone from an instrument that would fill a room to one thats a handheld.

One problem with Raman spectroscopy has been that the light scattering is minuscule. The way around this is to use a surface-enhancera device that magnifies the signal from the sample.

Bells team uses silver and gold nanoparticles for this, a common technique. What his team is doing, though, is putting the particles in a polymer gel. They remain active but are accessible to light, he says.

What he has in mind are stamp-sized pads with a protective covering over the gel. Peel back the covering, expose the gel and swab it on the surface to be tested.

The other challenge is canceling out background noise and focusing on the material of interest, a process akin to putting a tuner on a radio.

We have a long list of target molecules we are working our way through, developing modifications which promote binding of our targets of interest and discourage binding of interfering materials, Bell says.

Target molecules include underground drugs, chemical and biological weapons and substances like PETN (pentaerythritol tetranitrate), the explosive Abdulmutallab concealed in his skivvies before boarding the Northwest Airlines flight to Detroit last Christmas in Amsterdam.

Bells swab detection, and techniques like it, will be good for targeted searches. But they dont solve the problem of mass infrastructure such as airports, rail stations or even military checkpoints. This is the challenge Wolfgang Koch is putting his mind to at the Fraunhofer Institute for Communication, Information Processing and Ergonomics of Wachtberg, Germany.

Kochs team developed a data-fusion system for tunnel-like spaces such as hallways or corridors using ready-made laser scanners, video cameras and tracking sensors. Its about data integration. The principal problem with chemical sensors and sniffersthe artificial equivalents of nosesis poor resolution, he says. We are not able to localize smell, associate the smell to an individual and track him as he moves.

This data fusion aims to tie the input from different types of sensors together in a meaningful way, freeing human security from some of the workload inherent to routine tasks so they can be more observant. Access areas like corridors mean people enter and leave naturally. We can equip the hall with chemical sensors. They are not expensive, you can have several of them in a sniffing wall, Koch says. Data-fusion algorithms combine output of all sensors at all times and combine them with the position of all persons at all times. You can associate trace signatures with an individual. A suspect can then be electronically tagged with a label, followed and questioned. The next step for Koch is to set up a pilot project with the system.

There will likely be no single solution to security in airports, rail stations and other areas people pass through. It does seem that some type of data linking will be necessary, given the rapidly expanding universe of scanners and sensors.

Not everyone is happy about this. The academic activist group Transnational Institute (TI) of Amsterdam, for one, warns of a NeoConOpticon, its term for the rise of a security-industrial complex (think military-industrial complex) in Europe. TI decries the mania for surveillance systems – a splendid discussion for classrooms and dissertations, no doubt, but one that loses traction in the real world of crime and terrorism.

Koch sees the issue of heightened security from a different perspective. It gives us back a piece of normality in the infrastructure.

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