Editors: Schubert H, Rimski-Korsakov A
Publisher: Springer
ISBN: 978-1-4020-5158-6
Conference information: Stand-off Detection of Suicide Bombers and Mobile Subjects

Abstract: Fast, selective, sensitive and inexpensive detection techniques are highly required concerning the identification of planned terrorist attacks involving explosive, chemical or biological materials. State of the art are cost intensive equipments used e.g. in airport portal systems or swapping techniques (Imaging by X-ray, TeraHz-, MMwave, NQR, neutron activation techniques, electronic noses, IMS). We propose the development of substance specific low cost sensors, which can be installed as self reporting sensors in containers, compartments, wagons etc., used as hand held systems or sniffing devices which analyse the content of explosives in the gas phase. The basic sensor concept uses mass-sensitive devices coated with molecularly imprinted polymers (MIP). The components are cheap promising lowcost detection devices which could be applied for the passive as well as active sensing of explosives like TNT, DNT or TATP at short-range distances of about one meter. In the case of active sampling the MIP sensor will be combined with a suitable air-sucking system. Molecular imprinted polymers (MIPs) are highly cross-linked polymers. Like enzymes they possess a high affinity and selectivity for the adsorption of a special target substance (template molecule) which is present only during the MIP-synthesis and is afterwards extracted. This yields to a finished polymer with special and very selective binding sites for the former template. MIPs are very inexpensive, rapid to synthesise and they are already applied as substance specific solid phase extraction materials in the liquid phase. Preliminary results /1/ of synthesized particulate TNT-specific MIPs showed the effective adsorption capability of the material for TNT vapours. Moreover first experiments using direct UV-initiated polymerisation of TNTMIPs produced thin films which can be used in combination with different sensor materials. The response time reached with so-called quartz crystal microbalances, QCMs, is in the pg per minute range. Improvement of the MIP capacity will lead to shorter detection times (ca. 1 s). Overall objective of the proposed study will be to achieve a MIP sensor performance making them usable for short range stand-off detection (1-2 in). The TNT adsorption characteristics of layered MIP-material (pg to ng in seconds-range) has to be improved by varying the synthesis conditions and using QCMs as fast screening tool. The second step of the proposed work will be to coat so-called FBARs, mass-sensitive piezoelectric sensors/arrays (Film Bulk Acoustic Resonators, Cooperation with Siemens) with the improved TNT-specific MIP. Realistic measurements will demonstrate the performance of the cheap sensor prototype
Author keywords: suspension polymerization

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