1.9.4 Security: Application Profile: Detection of Chemical, Biological, Radiological, Nuclear, Explosives (CNRNE)
Short application description
This application area specific considers approaches to the detection of harmful substances associated with a security threat, such as a chemical or biological agent.
Current solutions to this involve a range of machines and technologies. Detection of explosives residue is typically carried out by swabbing the item to analysed, and then processing this sample with an ion mobility spectrometer. This can be configured to not only detect explosives, but also traces of narcotics. Explosives detection trace portals (or ‘puffers') use a non-contact method, blowing particles which are then analysed using ion mobility spectrometers. These are currently produced by Smiths Detection and GE Infrastructure, and can be found at a number of airports and other high profile locations.
Identification of chemical agents (whether chemical weapons or toxic chemicals) typically requires another device. The detection mechanism may be IMS or Fourier Transform Infrared Spectroscopy. Devices in a variety of forms are available, from handheld units for first responders, to units which are intended for continuous monitoring of a given location. The technology used for detection of biological agents often uses Polymerase Chain Reaction (PCR) and is also available in portable forms.
This is an area of high interest, particularly for governments, and there is a wide range of research work being carried out this area. Nanotechnology offers the possibility to make smaller, more sensitive and integrated detection platforms for each of these substances. These could typically be used in transit points like airports, train stations, seaports and borders to prevent the transport of CBRNE material.
A very wide array of technologies are being considered for detection of chemicals, including conductance sensors and conductive polymers, field effect transistors, piezoelectric sensors, field effect transistors, piezoelectric sensors, surface acoustic wave sensors, flexural plate wave sensors, sensor arrays, optical fibres, cantilever mechanism, chemiresistive sensors, chemicapacitive sensing and spectroscopic methods. For more detailed descriptions of these approaches, please go to http://www.observatorynano.eu/project/document/890/.
Detection of Biological Substances
Work being carried out in the healthcare industry on the detection of pathogens, toxins and other substances has applications in civil security. One of the primary events triggering concern about the weaponization of biological substances were the anthrax attacks of 2001, in which anthrax spores were sent by mail to US media outlets and senators, resulting in the deaths of five people.
Nanotechnology-enabled detection methods include the use of metallic nanowires, to which are attached antibodies corresponding to specific pathogens. Fluorescent antibodies are then added, which bind to any pathogens which are present. Measurement of the fluorescence then indicates the presence and concentration of pathogens.
A sensor developed by NASA uses an array of vertically aligned carbon nanotubes, each tipped with a probe molecule. When the probe molecule comes into contact with a target substance, an electrical impulse is generated. A variety of different probing molecules can be used, enabling a single array to detect multiple substances.
Detection of Radioactive and Nuclear Material
A detection technology which nanotechnology may improve is the use of scintillators; materials which emit photons when exposed to radiation. Materials including zinc oxide nanoparticles may work as scintillators but demonstrate improved energy resolution.
Detection of Explosives
Explosive detection can be achieved with ion mobility or Raman spectroscopy. A group led by Anja Boisen at DTU Nanotech is developing explosive sensors which use a range of detection methods, including SERS, cantilever sensors, micro calorimetric sensors and colorimetric sensor arrays. The cantilever sensors measure changes in surface stress, temperature or mass to detect gases (as well as antibodies and proteins). Timothy Swager at MIT has developed methods to identify TNT using electronic polymers; this technology is being commercialised by Nomadics.
The specific functional requirements of the detection of CBRNE substances depend heavily on the specific substance being targeted, and the environment in which sensing will be carried out. However, these general functional requirements are common to almost all applications.
The reliability of a detection device describes the extent to which it generates false positive or false negative results. Whilst the consequences of a false negative result can be very severe, it is important to note that excessive false positives also have a cost, requiring investigation and response.
The sensitivity of a device is often expressed as the quantity of a substance required to generate a detection result. This is measures in parts per million (PPM) or parts per billion (PPB). The target sensitivity depends on the substance being detected; in the case of anthrax, a single spore can be deadly, and so this should be the target sensitivity threshold.
Stability relates to the consistency of detection performance in a range of environmental conditions - such as differing temperatures, vibrations, shocks.
The cost of a detection device, in relation to its lifetime and effectiveness, is a critical factor. An explosive detection sensor for an airport is likely to be in constant use, and thus a higher cost can be amortised over a longer time period and a greater number of operations. A node in a distributed sensor network, which may need to be replaced more regularly, should typically have a lower per piece cost.
The speed with which a detector operates is an important factor in many applications. If a harmful substance is present, it should be detected in time to mitigate its effects; to order an evacuation, or to stop a vehicle carrying dangerous material.
Devices which a not connected to mains supply, such as portable detectors, also require low power consumption.
Most of the detection applications described in this chapter occur outdoors, and so the detection technology must withstand a range of environmental conditions, including high and low temperatures, direct sunlight, wind and rain.
Early Warning Biohazard Water Analyzer
This device uses the nanotube detection technology developed by NASA and described in section 3.1. Due for release in April 2009, the Analyzer will detect waterborne microorganisms, including E.coli and Cryptosporidium.
P.Eye Explosives Detector
Launched in February 2009, the P.Eye detector is designed by Portendo. The device utilises Raman spectroscopy to identify explosive substances, and is designed for ‘stand-off' use, in which a laser beam is use to detect substances from some distance away.
The Nexsense C, produced by Selex Galileo, is a portable chemical detector which uses Field Asymmetric Ion Mobility Spectrometry (FAIMS). The FAIMS detector is produced by Owlstone Nanotech.
Fido® Explosives Detector
The Fido® detector is sold by ICx Technologies, and uses amplifying fluorescence polymers (AFP) to detect explosives in concentrations of parts per quadrillion (ppq). This technology is developed from Timothy Swager's work at MIT. The device itself weighs 3 pounds (1.5 kg), making it highly portable. (The device is named as a nod to the explosives sniffer dogs, which have a comparable sensitivity to explosive traces).
Economic Information and Analysis
Taking a limited definition of nanotechnology-enhanced detection for security applications, the value of current products is likely to be rather small, in the range € 1- 20 million. This is difficult to establish definitively; no market studies have been carried out, and few of the companies report their revenues publicly.
Selected Key Companies Profiles
Owlstone (http://www.owlstonenanotech.com/site.php) started life as a spin-off from the University of Cambridge, and is now a wholly-owned subsidiary of Advance Nanotech. The company has developed a Field Asymmetric Ion Mobility Spectrometry (FAIMS) detector which is created with a replicable silicon etching process. The FAIMS chip enables simultaneous detection of a range of substances.
Nanomi (http://www.nano.com/) has developed a detection chip which employs a random network of CNTs, functionalised with specific analytes. The company's NanoTectTM environmental monitors claim to be able to detect low concentrations of gases. The main application is considered to be industrial use, rather than security. Nanomi received a grant totalling $1.26 Million from the Department of Homeland Security in 2007.
ICx (http://www.icxt.com/) has also developed a detection chip which uses functionalised CNTs. One of it's subsidiaries, Sensiq (http://www.discoversensiq.com/products/sensiq/) has a developed a detector for liquid explosives (hydrogen peroxide and triacetonetriperoxide) and a TNT detector which uses a semiconducting polymer film, developed by Timothy Swager.
Xintek (http://www.xintek.com) develops a variety of nanotech based field emission technologies, including a x-ray source. The company has a joint venture with Siemens for medical detection.
Kromek (http://www.kromek.com), formerly Durham Scientific Crystals (DSC), develops Cadmium Telluride based x-ray detectors. The company supplies material to the European Space Agency (ESA), and has evolved from CdTe materials to produce sub-assemblies and end-user products. The company had 38 staff in 2008.
 A Better Liquid-Explosives Detector
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