Restrictions on liquids in carry-on bags on commercial airliners could become a thing of the past thanks to a revolutionary nano-electric device which detects potentially hazardous liquids in luggage in a fraction of a second, according to a team of German scientists. Writing in the journal Superconductor Science and Technology, the researchers at the Forschungszentrum Juelich in western Germany 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.
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.
But the German researchers at Juelich 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 to span low and high frequencies to provide a far more detailed "fingerprint" of the liquid, according to the report in the scientific journal.
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, the scientists write.
This range is what Dr Knut Urban, head of microstructure research at the centre, believes sets the system apart from other detection devices.
According to Urban, systems that measure only a small part of the complex fingerprint could prevent security authorities from assessing all potential threats. He cited the example of the 2006 terrorist attempt to detonate peroxide-based liquid explosives on board aircraft travelling from Britain.
"It is very difficult to distinguish between hydrogen peroxide and water," he was quoted as saying. "They have a similar chemical make-up and look exactly the same. Fortunately, the plot in London was foiled before it was carried out, but the technologies developed since then would still struggle to identify the difference between the two liquids without separating them from other luggage."
He added: "As far as we know, no other concept at the moment allows for identification of liquids regardless of container. You really need to be able to measure the entire molecular fingerprint and our approach can do this. I believe the technical device that comes out of this will be flexible enough to identify harmful substances that have not yet been invented by the terrorists."
Since publishing their research in the journal Superconductor Science and Technology, the team in Juelich has received interest from industrial partners to develop an advanced prototype of the system, according to German news reports.