Security agencies at airports, ports, and borders generally use one of several types of machines to detect trace amounts of explosive materials, the most common of which is ion mobility spectrometry, or IMS. Gas chromatography (GC) is often coupled with IMS to improve performance. The down side is GC typically requires bottled gas, which makes the systems more difficult to use.
Koratkar sees his technology as the first practical nanostructure-based gas detector that's viable for commercialization.
"Our results show the graphene foam is able to detect ammonia and nitrogen dioxide at concentrations an order of magnitude lower than commercial gas detectors on the market today," he says.
Sweating the small stuff
On another front, university researchers have found a way to address deficiencies in common scintillation radiation detection technology. Scintillations are minute flashes of light that are produced by certain materials when exposed to radiation.
A team at Georgia Tech Research Institute is utilizing novel materials and nanotechnology techniques to improve sensitivity, accuracy, and robustness of radiation detection.
Standard scintillation detection technology is proficient at detecting gamma rays and subatomic particles emitted by nuclear material, but it requires large difficult-to-produce crystals grown from sodium iodide or other materials. These crystals are fragile, bulky, and vulnerable to humidity.
The Georgia Tech approach uses a nanopowder glass material composed of rare-earth elements halides and oxides.
“Our glass detector has the advantage of simple preparation, stability, and does not need to be enclosed or otherwise protected,” says Bernd Kahn, of Georgia Tech’s Electro-Optical Systems Lab. Kahn says the Georgia Tech detector can be used by law enforcement as a hand-carried or vehicle-carried radiation monitor to survey areas and people, or as a fixed monitor to scan passing vehicles or foot traffic.
Radiation detection is a growing requirement in law enforcement and public safety agencies. The state of Illinois, for instance, has deployed 6,200 radiation detectors in police and fire vehicles across the state. Radiation detectors have been in the hands of some local police departments, as well as the state police, in New York since 2008. There are some 4,000 pager-sized radiation detectors on the belts of first responders in 150 New York area agencies.
The Department of Homeland Security is behind the push to get radiation detection capability on America's streets as it expands its nuclear security program to meet the threat of a terrorist nuclear, or dirty bomb, device.
Kahn's work involves improving the crystals. Regular scintillator crystals must be transparent to light, which provides its ability to detect radiation. A perfect crystal uniformly converts incoming energy from gamma rays to flashes of light. A device called a photo-multiplier then amplifies these light flashes so they can be accurately measured to provide information about radioactivity.
However, Kahn says, results on conventional devices are unreliable because some crystals scatter the luminescence created by incoming gamma rays. That scattered light can’t be photo-multiplied in a uniform manner, badly skewing the readings, which are manifested as false positives.
To overcome this issue, Kahn reduced the particles to the nanoscale. When a nanopowder reaches particle sizes of 20 nanometers or less, scattering effects fade because the particles are now smaller than the wavelength of incoming gamma rays.
All of these emerging technologies indicate an evolving role of law enforcement in terror threat detection—which puts law enforcement in a preventative, rather than a response, role. These technologies may ultimately find their way into new police and lab protocols designed to either prevent terror attacks or accelerate response measures.