With the increased threat of terrorism, airports, police, and the military are on high alert. Currently the most sensitive and reliable way to detect a bomb is with a well-trained dog. But USTAR researchers at the University of Utah are using nanotechnology to develop a handheld device that could eventually put bomb-sniffing dogs out of work.
During the legislative session the potential for security threats are always taken seriously, but this year the number of threats are on the rise. Utah Highway Patrol Trooper Dan Huber is making sure the capitol is safe for citizens and legislators alike. He and his bomb-sniffing dog travel the capitol grounds looking for danger. “Diego, he is a five year old Belgian Malenois, he came from Holland. A dog’s nose is 300,000 times more sensitive than a humans nose. And so traces of explosives, any kind of a little bit of gunpowder that’s burn inside of a shell casing, he can find that.”
Dogs are currently the most effective way to detect bombs. They can smell multiple types of explosives at very low concentrations. Huber says that makes dogs an important part of a security team. “He’s kind of like an insurance policy for the state because when you need one and don’t have one, it’s really hard to get one. It’s another added layer of defense that we use to protect people here at the capitol and throughout the state.”
But dogs are expensive to train, feed, and house, sometimes they don’t want to work and they can develop health problems. Deputy Collin Gordon with the Utah County Police Department worked with his German Shepherd Yargo for five years. “We responded to a lot of different types of calls, obviously bomb threats whether that be in a business, or a school, a government facility. We did a lot of protection details for dignitaries when they came in. I was on two different presidential details during my time.”
They never found a live explosive device while deployed, but Gordon says Yargo was able to detect up to 22 different explosive odors. Then last year Yargo developed sclerosis and arthritis in his back and was retired out of service. “It’s a bit of a nice break at times, but I do miss it.”
For decades, the US government has been investing in new technologies to detect explosives. Ling Zang, a researcher at the University of Utah, has received funding from the Department of Homeland Security. He’s trying to develop a handheld bomb-sniffer that can detect many explosive types at the same time, just like a dogs nose. “We are working to target all kinds of typical explosive including nito based, peroxide based, inorganic based explosive,” says Zang.
To find low concentrations of explosive vapor, Zang is using nanotechnology. That’s the study of materials with dimensions of between 1-100 nanometers—it’s very small, about 50,000 times smaller than the width of an average human hair. Professor Mark Porter is director of the University of Utah’s Nano Institute: “What is nanotechnology? Well of course it’s been around for a long time. Nanoparticles or nanomaterials really sit between to kind of things were really familiar with. So we’re familiar with atoms and molecules and were familiar with bulk materials. So as you begin to build things up from atoms to a bulk material, properties change dramatically.”
For example, Porter says a solution of gold atoms are almost colorless, but as atoms come together to form gold particles the color changes to red and eventually to the color we know of as bulk gold. He says modern nanotechnology scientists are exploiting this phenomenon to create new materials that can do amazing things. Zang is building nanofiber materials that can sense trace amounts of explosive. The fibers are assembled into a web containing small pockets and explosive molecules get trapped. “By piling up a lot of fiber together we can form this kind of porous film. So whenever you have a molecule like TNT flowing in the air, so whenever you catch that it will be able to accumulate. So that’s why our material can be so sensitive to detect even trace amounts of explosives.”
But accumulating explosive in the nanofiber film is just the first step. “After you catch up and accumulate this TNT or some other explosive molecule within your sensor materials, now comes to a second step. Your materials should be able to show some response to that vapor molecule explosive,” says Zang.
The nanofibers designed by Zang’s lab emit light and conduct electricity. When explosive vapor is present, the light becomes dimmer and the electrical properties change. These two features allow them to tell how much and what kind of explosives are present. “So why the explosive can give that kind of electrical optical signal to your nanofiber? That’s based on the chemical reactions. Based on a different type of explosive reacting with a different type of nanofiber, which is composed of different type of building block molecules within the nanofibers.”
Each nanofiber material built by Zang and his colleagues binds and reacts to a different explosive type. And since the nanofibers are so small, multiple explosive detectors can be contained within a single device. Last month Zang received funding from Utah’s Governor’s Center for Excellence Program to begin developing a prototype of the bomb sniffing device. He says the task requires bringing multiple experts together. “When you’re trying to get a prototype device you need some people from electrical engineering, from materials science, from physics, from chemistry. So we work as a team to get the real device which can be used one day.”
Deputy Gordon thinks it would be a great thing if a new bomb-sniffing device is developed, but doubts they will stop using dogs. “I think that if we could look at using new technologies in cooperation with the dogs then you start to use all of the tools that are available which is a benefit to law enforcement the community as well.”
Zang hopes to have a prototype of his explosive detector ready in the next 2-3 years.
This story originally aired 2/28/11.
UPDATE: Ling Zang's new company, Vaporsens, is also developing a detector to identify trace levels of methamphetamine.