Sensors explosives detection

Trace portals could also be used for bulk detection because of the likelihood that a mass of explosive concealed on the person would present an adequate chemical signature. The combination of a trace and anomaly portal would provide a powerful multi-sensor platform that would offset the limitations of the individual technologies. Currently, a commercially available multi-sensor explosives detection personnel portal that combines trace and anomaly methods does not exist. 

Develop robust and reliable sensors for detection of chemical agents, biological agents, radioactive materials, and explosives. 

This chapter provides an overview of the basic principles and designs of such sensors. A chemical sensor to detect trace explosives and a broadband fiber optic electric-field sensor are presented as practical examples. The polymers used for the trace explosive sensor are unpoled and have chromophores randomly orientated in the polymer hosts. The electric field sensor uses a poled polymer with chromophores preferentially aligned through electrical poling, and the microring resonator is directly coupled to the core of optical fiber. 

Therefore, there are many considerations that must be taken into account in the design and synthesis of conjugated polymer sensors for explosive detection. Not only must the electron transfer process be efficient, but solid-state aggregation must also be avoided to retain maximum sensitivity. Strong binding of analyte to the polymer is necessary, which the 7l-acidic nature of TNT and DNT facilitate via... 

Figure ll ICx Technologies SeaDog underwater explosives detection sensor mounted on an autonomous underwater vehicle. Figure courtesy of ICxTechnologies. 

This concept is in essence a chromatographic effect similar to that observed in gas chromatography (GC), with the conjugated polymer film acting as the stationary phase. It is possible that like in GC and other candidate technologies for explosive detection, these responses could be empirically standardized for expected analytes of interest and sensory devices caHbrated to deconvolute temporal quenching signals to determine which analytes are present. This would further enhance the selectivity of what is already a very selective sensor for TNT and related compounds. 

EXPLOSIVES DETECTION USING ULTRASENSITIVE ELECTRONIC VAPOR SENSORS FIELD EXPERIENCE... 

The Fido technology is currently under evaluation for use by U.S. military forces. The Fido X and Fido XT are available as commercial off-the-shelf (COTS) items. Consequently, the technology is adequately mature for commercial deployment. However, as a platform technology, the AFP sensor and Fido detection system support broad application to meet explosives detection needs. Further, Nomadics has incorporated the amplification features of AFP into other sensor mechanisms aimed at the detection of analytes that are not explosives related, including other chemicals and compounds of interest in the biomedical and food safety fields. Thus, while the technology is mature enough for commercialization, its potential is far from fully exploited. 

Chapter 7, Explosive Detection Using Ultrasensitive Electronic Vapor Sensors Field Experience, applies some of the concepts of the preceding chapters by describing system development work in field conditions. It describes some surprising head-to-head comparisons between dogs and electronic sensors. 

There is a growing need to sense molecules for applications as diverse as waste management, explosives detection, and disease prevention. Goals of chemical sensor development are to create devices that require little power and that are robust, sensitive, selective, fast, compact, and inexpensive. In this chapter, we describe optical techniques based on semiconductor luminescence that are promising methods for chemical sensing applications. 

Fig. 2. A disposable thick-film voltammetric sensor for detecting organic explosives.

Orghici R, Wilier U, Gierszewska M, Waldvogel SR, Schade W (2008) Fiber optic evanescent field sensor for detection of explosives and C02 dissolved in water. Appl Phys B 90 355-360... 

Electrochemical sensors that detect specific and preselected analytes are now incorporated into convenient encapsulated hand-held packages and are in routine commercial use. A few multisensors for explosives or trace amounts of gases (e.g., the "Caltech nose") also exist. However, the shelf life and re-usability of all these sensors have been a vexing problem. 

The author acknowledges here the contributions of many of his colleagues, and research students. In particular, he acknowledges Professor Philip Bartlett (Southampton University, UK) for the source of some of the material taken from reference [1]. The work has also been financially supported by the Engineering and Physical Sciences Research Council (UK), The Royal Academy of Engineering, and industry. The author also thanks the NATO Science Program for the financial support to host a NATO ARW on the topic of Electronic Noses/Sensors for Detection of Explosives near Warwick University, Coventry. 

D. Walt, Optical sensor microarrays for explosives detection, in Electronic Noses and Sensors for the Detection of Explosives, (eds JW Gardner and J Yinon), NATO ASI Series, Kluwer Academic Pubhshers, Dordrecht, 2004. 

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