Beetles that spew acid at predators have inspired inventors to create what may be the next wave of security devices for automated teller machines (ATMs). Their new system would eject hot foam at any would-be thieves attempting to rob the machine.

Bombardier beetles use a mixture of hydroquinone and hydrogen peroxide, along with other chemicals, in a potent chemical defense. This tiny insect has one of the sternest defense mechanisms in the world for an animal of its size.

After the mixture is compounded in the abdomen of the beetle and ejected, the acid is powerful enough to kill ants. Accompanied by a loud popping sound, this spray can even scare off frogs who were hoping for a quick snack.

Researchers at the ETH Department of Chemistry and Applied Biosciences in Switzerland wanted to develop this unique system into a new security design.

"When you see how elegantly nature solves problems, you [realize] how deadlocked the world of technology often is," Wendelin Jan Stark, a professor from the ETH Department of Chemistry and Applied Biosciences, said

The new technology is composed of layers of plastic, each of which holds a reactant. When the surface of the machine is damaged during theft or vandalism, the chemicals mix, producing a hot, potent acid.

Each layer is composed of a network of honeycomb structures. Half of these are filled with hydrogen peroxide, and the remainder with manganese dioxide. When the cells are ruptured, the chemicals react, forming water, oxygen, and heat. The chemical product can reach temperatures over 175 degrees Fahrenheit.

Researchers believe their new invention could do more than just protect ATMs. These could be used to protect nearly anything, including rare trees, which could otherwise be damaged by animals.

Current technology to secure ATMs is capable of spraying attackers with chemicals. However, these systems are automated, and will not function when the electricity is shut off. Unlike the new passive system, motor-driven security devices are also expensive.

The new security layers can also incorporate a mixture of dye and DNA encased in nanoparticles. This can mark money, which makes it unusable, and the DNA allows investigators to track cash following a robbery. In addition to defacing the money taken in a heist, the dye will also mark the thieves, making identification easy during an attempted getaway.

Mechanisms like this one are "imitating nature and [realizing] simple ideas with high-tech methods," Stark stated in a press release.

Development of the new protection system was profiled in the Journal of Materials Chemistry A.

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