Engineers tasked with protecting bank ATMs from thieves have drawn inspiration from an acid-spitting beetle.

The minute and colorful bombardier beetle, found throughout Central Europe, was well-versed in chemical warfare well before WWII scarred the countryside. The nimble little beetle, no more than a centimeter long, can not only spray would-be attackers with a gaseous cloud of acid, but can -- when necessary -- ignite said cloud and cause a mini explosion.

The insect has two chemical-storing chambers: one for the caustic spray and one for the catalytic enzymes that set off the explosion. The two tricks can kill ants and scare off frogs.

"When you see how elegantly nature solves problems, you realise how deadlocked the world of technology often is," said Wendelin Jan Stark, a professor at ETH Zurich, a technology institute in Switzerland.

Inspired by the beetle, Stark and his fellow researchers developed a honeycomb-like plastic structure that houses two chemicals: hydrogen peroxide and manganese dioxide. A sudden impact, such as a robber attempting to jimmy open an ATM, causes the two chemicals to mix, triggering violent chemical reaction that produces water vapour, oxygen and heat -- enough, researchers hope, to ward off criminals.

ATM and bank transport vehicles have been increasingly targeted by thieves, and technology could be one way to thwart such attempts. Many ATMs are already outfitted with various protections, but most of these are mechanized, ineffective and cost-prohibitive.

"A small motor is set in motion when triggered by a signal from a sensor," the researchers claimed in their new study. "This requires electricity, is prone to malfunctions and is expensive."

The new ATM-protecting technology is detailed in the latest issue of Journal of Materials Chemistry A.