Detecting Hidden Threats: CBRN Detectors from Security Frontiers

As weapons of mass destruction can cause untold disasters, there is a huge demand for advanced detection technologies. Chemical, biological, and radioactive material detectors are essential frontline defense tools to avoid potential threats.

On October 29, 2010, two seemingly normal packages were found on a cargo plane from Yemen to the United States. Each package contained a plastic bomb with a detonating device. Although no casualties were caused, the US aviation management is stricter than before. Terrorists carrying weapons of mass destruction claim that biological, chemical, radiological and nuclear (CBRN) attacks do not occur on distant battlefields, but are very likely to occur at home.

CBRN detection can respond to a variety of hazardous materials. In the past, handheld detectors were developed based on ion mobility spectrometry. Dieter Rothbacher of Hotzone Solutions believes that ion mobility spectrometry-based devices can provide an indication of problematic objects; however, it cannot identify and analyze more information.

In recent years, many products based on Fourier transform infrared spectroscopy have been developed. "Such devices can analyze objects in liquid or solid form, allowing users to detect the storage of gaseous substances," Rothbacher said. "Also, more analytical devices have embedded databases that can provide on-site information for identification." Now, the detection technology on these devices has greatly improved in sensitivity and reliability, so the accuracy rate has also been improved.

Lou Banks, marketing manager for Bio-Defense, Idaho Technology, said that in the field of bio-agent detection, polymerase chain reaction technology has been refined from laboratory settings to be enhanced in handheld bio-agent detectors. "PCR is a multi-molecular technology that can detect the amount of pathogen DNA, which can significantly improve the level of sensitivity."

Biochemical agent detection has benefited from matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). "PCR is a good choice for identification, but the combination of MALDI-TOF and a large number of spectra has become a development focus," said Rutger Gaasbeek of IB Consulting. "Although most applications are for military purposes, they are gradually developing towards civilian use, such as in the field of medical care."

For chemical agents, improved sensing capabilities extend the detection range and increase sensitivity. "Previously, chemical warfare agent capabilities only covered 30 toxic industrial or chemical gases," said Osmo Anttalainen, Vice President of Environics R&D Programs. "Recently, handheld detectors have increased their gas detection range, so domestic security has improved detection coverage."

Radioactive material detectors are generally divided into two categories: personal radiation detectors (PRDs) and radioisotope identification devices (RIIDs). "PRDs are used for personal protection and basic search functions," said Lester Koga, PM of Morpho Detection, "RIIDs can be used to identify radioisotopes in order to determine the threat level of the material being detected (special nuclear material, medical, industrial or natural radioactive material)".

To determine whether the detected radioactive material is from a radiotherapy patient or a special nuclear material, accuracy is the primary factor. "Generally, the lower the lower energy resolution percentage, the more accurate the isotope reading, which can reduce false positives and false negatives," Koga said.

Energy resolution High purity germanium (HPGe) below 1% is the gold standard for available materials, but is not operable at room temperature and so requires cooling. This limits the size, weight and battery life of such detector equipment, Koga explained.

New detector materials, such as cadmium zinc telluride (CZT), can be used in lighter and more portable devices without compromising radiation detection accuracy. "With energy resolution less than 2%, CZT can improve detection portability and correctly identify radioisotopes in a more user-friendly data package than HPGe compared to sodium ions," Koga said. The barrier to widespread adoption of CZT is that it costs more than sodium ions.

Defense Frontier

Handheld, mobile and static detectors often use the same basic sensors, although the technology used is sometimes too large or time-consuming for portable applications. There has been a lot of investment in creating lighter and longer-lasting portable devices. In common equipment, portable and static detectors have increased the functionality of CBRN detection. The main differentiator is the user and what the user wants to achieve with these devices. "CBRN experts, law enforcement and first responders may have very different tasks and goals when using detectors. And each scenario requires specific equipment to work best," said Craig Johnson, CEO of Field Forensics.

Rothbacher believes that the purposes and details of the tasks that users want to achieve are diverse, so handheld, mobile and static detectors are frequently used. The larger the detection range of the equipment, the more money it saves. The software pre-installed in the equipment can be improved through debugging and troubleshooting. In some other devices, changes are not made to the software. At present, third-party devices and embedded software are not interoperable.

Anttalainen says that handheld devices are limited by size, weight and power consumption, while mobile and static systems are less affected by these factors and therefore perform better. Ease of use and maintenance requirements are also performance differentiators that need to be considered. It should be noted that mobile detectors can be used in a static manner, so they can be used as satellite detection points in a large detection network controlled by a central command center. Mobile detectors will last longer when used as static devices if the battery is sufficient.