System detects liquids in luggage

Restrictions on carrying liquids on commercial airlines could soon be lifted with the development of a system that can quickly identify dangerous substances in passenger luggage.

German researchers at the Forschungszentrum Jülich claim that they have been able to do this using an optical approach that detects all existing and future harmful liquids within one fifth of a second.

The technique uses electromagnetic waves that are able to reflect information about a substance’s internal molecular dynamics. The method is known as Hilbert spectroscopy and operates in the frequency range of 10GHz to 1THz.

This range is what Prof Knut Urban, head of microstructure research at the centre, believes sets the system apart from other detection devices. Existing detectors are largely based on electromagnetic theory, but are also restricted to working in the lower gigahertz scale and can only analyse certain features of a liquid’s molecular structure.

Researchers at Jülich have overcome this problem by using a nano-electric device known as a Josephson junction. This accumulates the frequencies of light reflected from the liquid when exposed to monochromatic electromagnetic radiation. As a result, the device is able span low and high frequencies to provide a far more detailed ‘fingerprint’ of the liquid.