Thieves tampering with an ATM in an effort to get their hands on its cash could soon find themselves sprayed with hot foam, and a lot more besides, if technology developed by Switzerland’s ETH Zurich gets bought up by banks.
Inspired by the behavior of the bombardier beetle, which, when it finds itself in a tricky situation with a predator, emits an explosion of gas in an act ETH Zurich describes as “the most aggressive chemical defense system in nature”, the team of researchers has created a special layered film that, when damaged, produces a spray of hot foam.
The film has a honeycomb structure comprising hollow spaces filled with one of two chemicals: hydrogen peroxide or manganese dioxide. When the film is broken, a clear lacquer layer separating the two chemicals ruptures, causing them to mix. This is where things get interesting for the unsuspecting criminal.
According to ETH Zurich, the coming together of the two chemicals causes “a violent reaction that produces water vapor, oxygen and heat,” with the sprayed foam reaching a temperature of as high as 80 degrees.
Besides a faceful of hot foamy liquid, the robber will also end up with a bunch of dyed banknotes (if they get that far) covered in DNA enveloped in nanoparticles.
“If the film is destroyed, both the foam and the dye are released, thereby rendering the cash useless,” the team explains on its website. “The DNA nanoparticles that are also released mark the banknotes so that their path can be traced.”
While technology already exists that can spray banknotes in the event of a robbery, research member Wendelin Jan Stark says such systems require electricity and are known to malfunction. ETH Zurich’s technology, on the other hand, is reliable and relatively cheap to implement, with one square meter of film costing around $40.
So, now you know – if you’re passing by an ATM one day and see it erupt in a mass of hot bubbles, it’s a safe bet the person that emerges from the damp cloud of steam (possibly screaming) has been up to no good.