Hidden fingerprints can be now be revealed
quickly and reliably thanks to two developments in nanotechnology.
The current method for revealing prints involves coating surfaces with
a watery suspension of gold nanoparticles and citrate ions. Under acid
conditions, the gold particles stick to the positively charged
particles in the print.
The print is then developed using a solution of silver ions, which
chemically react to leave an outline of silver along the ridges of the
print.
However, the gold solution used in this method is unstable and results
are difficult to repeat – so Dr Daniel Mandler, Dr Joseph Almog and
their team at the Hebrew University of Jerusalem, Israel, have
developed a more stable solution be adding hydrocarbon chains to the
gold nanoparticles and suspending them in petroleum ether.
The prints produced using the new solution are very high quality and
are developed after just three minutes immersion time.
The team have also extended their technique for use on non-porous
surfaces, using a petrol ether suspension of cadmium selenide/zinc
sulphide. In this case, the chemical reaction makes the prints
fluoresce, so no additional developing stage is required.
Antonio Cantu, an expert in forensic science for the United States
Secret Service in Washington, said: “The techniques are revolutionary
and are apt to greatly improve the recovery of latent prints on
evidence.”
Dr Claude Roux, director of the Centre for Forensic Science at the
University of Technology, Sydney, Australia, said: “This use of
nanotechnology in the fingerprint community can bring novel and
practical solutions to develop and enhance latent fingerprints that
would otherwise remain undetected.”
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