Acid-spitting beetle could make ATMs more secure

So far, the most frustrating thing about ATMs is when they eat your cash card; however, proposed ATMs that spit acid could end up more of an annoyance, at least if you've got illegal intentions toward their contents. The Swiss team was inspired by bombardier beetles – which can cook up a spray of caustic acid when cornered – to create a new anti-theft feature.

The beetles mix together hydrogen peroxide and hydroquinone to make an aggravating chemical weapon that they can fire at potential predators. While it's enough to kill ants or give frogs a scare, the ATM version is slightly less hazardous.

The concept, developed by a team at ETH Zurich University, sandwiches tiny pockets of hydrogen peroxide and manganese dioxide in a honeycomb arrangement. Each different layer is separated by a clear lacquer, designed to smash under impact.

When that happens, the two chemicals mix and – among other things – create a hot foam, which rises to around 80-degrees centigrade (176 fahrenheit). That could be sprayed at attackers, the researchers suggest.

However, the ATM system wouldn't necessarily aim to blind thieves, but could instead make their loot easier to track. By building boxes out of the honeycomb pieces, and mixing an indelible dye with DNA nanoparticles that can be tracked down to a specific source, cash stored inside could be permanently marked and tagged if removed incorrectly.

The dye also means the notes are rendered worthless. The potential extends beyond ATMs, too, with suggestions that it could also be used for protecting any other objects that aren't to be touched, or as a way to dissuade animals.

The advantage over existing spray systems is said to be cost. Current technology uses a variety of pumps and motors; the foam created by the beetle-inspired setup is self-generating and applies itself automatically. The Zurich team suggests the sheets themselves could be made for approximately $55 per square meter.