Stopping Roadside Bombs

New detection technology is helping in Iraq.

The advanced technology of the U.S. military has so far met its match in Iraq in the form of improvised explosive devices (IEDs) triggered by garage-door openers, cell phones, and washing-machine timers. But this situation could be changing. New technology may make it easier to find explosives and bomb makers long before they can trigger a deadly roadside bomb.

One device the U.S. military now uses in Iraq can detect TNT vapors through bomb casings and even in land mines buried six inches underground. At checkpoints, it can smell explosive residues on the skin of bomb makers -- even if they used gloves and washed their hands several times after working with TNT. Furthermore, a second generation of the detector, based on technology at least thirty times more sensitive, could be available within one to two years, says Aimee Rose, a research scientist at R&D firm Nomadics, who's working on the new device.

According to U.S. Department of Defense releases, fifteen soldiers have been killed by IEDs since one such device seriously injured ABC news anchor Bob Woodruff and his cameraman on January 29. In fact, IEDs are the leading cause of U.S. combat deaths in Iraq, says deputy defense secretary Gordon England. The bombs have recently received more attention, as last month 600 military, industry, and academic leaders gathered in Washington, DC, to learn about and consider new solutions to the problem. IED efforts have come under the watch of a $3 billion organization led by a senior commander, retired four-star general Montgomery Meigs, former commander of NATO peace-keeping operations in Bosnia.

The TNT detector, first tested in Iraq in 2004, is now also being used in Afghanistan and in "homeland security" applications, according to Nomadics, the Stillwater, OK, company that makes the device. Instead of sensing particles of TNT, like other explosives detectors, the 2.7-pound handheld device sniffs vapors as effectively as a trained dog.

But the sensors have their limits. They cannot be mounted on a Humvee and used to detect IEDs as the vehicle drives around on patrol. Unless there is a favorable wind, the detector has to be right next to the TNT, Rose says -- close enough that the IED might be detonated before a signal is read.

For that reason, the device is used primarily to find bomb makers and their explosives before a bomb is planted. "There are far fewer bomb makers than there are bombs," says Melissa Brechwald, marketing projects manager at Nomadics. "If you get one bomb maker you're stopping exponentially more bombs from being laid."

Soldiers can use the devices at checkpoints, for example, to sample the air inside vehicles for traces of explosives, then either detain suspects or follow them in the hope of finding bomb-making factories, Brechwald says. The devices have also been mounted on robots for remote surveys of suspected bomb sites and weapons caches, she says.

The heart of the detector is a semiconducting polymer, originally developed by MIT chemistry professor Timothy Swager, that fluoresces when exposed to ultraviolet light. As air is pumped over this material, any TNT vapors will interfere with the fluorescence, causing it to dim. Electronics detect this change and relay the information to soldiers in the form of a bar graph and Geiger-counter-like sounds. The process takes just a few seconds, and after detecting TNT, the sensor can refresh itself in a few more seconds and be ready to test the next vehicle at a checkpoint.