When a bomb disposal robot destroys a suspicious package, crucial evidence that could trap the would-be bombers can be lost forever. But a device that lets the robot take fingerprints before blowing the package up would give police a much better chance of catching the culprits.
Fingerprints are comprised of secretions of amino acids, fatty acids and proteins, and are normally made visible in one of two ways. At a crime scene where the prints are fresh and still moist, they can be revealed with a dusting powder.
But if prints are old and have largely dried out, they can be disclosed by “fuming” suspect artefacts in a sealed cabinet with a vapour of cyanoacrylate - better known as superglue.
At a high enough concentration, the superglue vapour reacts with the organic fingerprint deposits to form a conspicuous white polymer that is easily photographed - even when the prints are faint.
However, getting a jerky remote-controlled robot arm to delicately dust a suspect package for prints could detonate the explosive if the bomb is fitted with a sensitive “trembler” switch. So engineers at the University of Calgary in Alberta, Canada, have worked out how to allow a robot to perform the cyanoacrylate fingerprinting technique without touching the package.
The major challenge facing Kristian Thomas and his colleagues was to get rid of the need for the fume-concentrating cabinet, since getting a robot to manoeuvre a package into a cabinet is too risky.
Instead they designed a superglue gun that a robot can use to direct a concentrated jet of fumes at the package. That means the robot can be controlled from a safe distance of 100 metres or so.
The gun comprises two cylindrical vials stuffed with steel wool soaked in superglue, with each vial surrounded by an electric heating coil. The coils heat the cyanoacrylate to 65 √Ǭ∞ to evaporate it, while a fan pushes the vapour out of a nozzle fixed to the robot’s arm. The large surface area of the steel wool accelerates the evaporation and allows the gun to produce a dense cloud of glue.
After about 15 minutes of fumigation, the person controlling the robot uses its high-resolution camera to snap any fingerprints that show up.
Source: New Scientist
