New Detector for Dangerous Fluids

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- The assembly shows the prototype of the detector (centre) and the fluid that is to be examined in a bottle. The light source is located to the left outside the picture. Photo: Forschungszentrum Jülich
Jülich physicists have developed a prototype detector, which can reliably and rapidly differentiate between liquid explosives and harmless substances. “Explosive liquids or fluid components from which explosives could be mixed aboard an aircraft, can be identified within split seconds by our method. Our process of controlling fluids is not only faster than others, it is also much more reliable. After all, carrying fluids in one’s hand luggage can be allowed again only, if dangerous substances are safely detected without long queues forming due to long detection times and false alarms”, explains Professor Dr. Knut Urban, Director at the Forschungszentrum Jülich.
Urban and his collaborators at the Institute of Solid State Research (IFF) use a special form of spectroscopy for their detector, which can analyse substances by way of electromagnetic radiation. Every fluid absorbs and reflects radiation of different wavelengths in a different manner and thus can be identified on the basis of its specific “finger print”. In doing so, the finger print is measured across a broad frequency spectrum from just a few gigahertz to some terahertz, which allows for a reliable comparison with reference data from dangerous fluids.
The heart of the so-called Hilbert spectrometer is a nanoelectronic part optimised for the analysis of liquids, a so-called Josephson contact. It functions as a highly sensitive, ultrafast and broadband sensor and, controlled by computer, converts the scanned spectrum into an electric signal. After measuring a time of 0.2 seconds, the detector reliably differentiates between various liquids such as water, ethanol, methanol, propanol and acetone on the one hand and dangerous liquids on the other.




