The bombardier beetle is a common beetle that exists on every continent except Antarctica. It is notable because it has a very sophisticated defense mechanism: when provoked, the beetle releases a chemical spray that sends predators running.
The one-centimeter-long bombardier beetle stores hydroquinone and hydrogen peroxide in two separate chambers in its abdomen. When it feels threatened, the two chemicals are released into a reaction chamber where they mix with enzymes and the mix is brought to a high temperature close to the boiling point of water. The heat triggers an explosion that sprays the chemical at the other animal. It kills ants and scares off frogs.
Researchers at ETH Zurich were inspired by this process and created a film that releases a hot foam when damaged. The film consists of layers of honeycomb structures containing either manganese dioxide or hydrogen peroxide, stacked on top of each other. When the film is punctured, the substances mix and create a hot foam that hits temperatures up to 180 degrees Fahrenheit.
“When you see how elegantly nature solves problems, you realize how deadlocked the world of technology often is,” says Wendelin Jan Stark, a professor from the ETH Department of Chemistry and Applied Biosciences
The film could be especially useful as a theft and vandalism deterrent for ATM machines. The researchers created a film that also contained a blue dye and DNA particles. When tampered with, the hot foam and dye were released -- the dye made the money useless and the DNA particles made the marked bills easy to track.
Currently, anti-theft systems are expensive and complicated, but the researchers say one square meter of this beetle-inspired film could be effective and would only cost $40 per machine.