New sensor for detecting plastic explosives

Researchers at the University of
Massachusetts Amherst have created complex molecules containing zinc
for use in portable sensors which can quickly and reliably detect the presence
of plastic explosives. Sensors containing the zinc complexes are also the first
devices which allow the user to identify which type of explosive is present,
since each metal complex has a unique response to an explosive. “This is a big
improvement over existing sensors based on polymers, since the metal complexes
can discriminate between closely related explosives compounds,” said Michael
Knapp, a professor of chemistry at the university. “This ability is a real
advantage for airport security personnel and law enforcement officials, who
need to quickly detect and identify what type of explosives they are dealing
with.” Results of the study by Knapp, doctoral candidate Meaghan Germain, and
undergraduate student Thomas Vargo were published on 23 April in the Journal
of the American Chemical Society.

Knapp and Germain currently
hold a patent for the zinc complexes, and are working with the UMass
Amherst Office of Commercial Ventures and Intellectual Property to
bring the technology to market. The research was supported by start-up funds
provided by the University of Massachusetts Amherst. The zinc complexes are
naturally fluorescent, but they lose this ability when exposed to chemicals
contained in plastic explosives, a phenomenon called quenching. Since each of
the complexes react by losing different amounts of their fluorescent ability,
they can be used to create sensor arrays that produce a different visual
display when exposed to different explosives. During testing, the sensors also
responded quickly, since the zinc complexes are very efficient at changing
energy states. “Of all the molecules that fluoresce, these go from a high
energy state to a low energy state like falling off a cliff,” said Knapp. “They
don’t lose energy gradually like metal complexes made with copper.”