Smelly helmet technology

"This helmet stinks," says Sally. But it's not because she doesn't wash her hair or has a rare scalp disease. It's because the helmet is damaged.

A new technology developed at the Fraunhofer Institute for Mechanics of Materials in Germany emits a stinky odor if a helmet develops any cracks.

Traditionally it's very difficult to tell if a helmet has microfractures, which render the helmet unsafe, but this new technology could be a simple way of gauging a helmet's efficacy.

At present tests have only been done on bicycle helmets, but there is scope for this technology to make its way into motorcycle helmets. The Fraunhofer Institute media statement reads: The process is therefore suitable for all products which are difficult to test for defects, such as cycle, motorbike and construction helmets.

How does it work? Well, it's mainly arcane majik... But odoriferous oils also help. Tiny amounts of these repugnant oils are encased in resin microcapsules and these microscopic 'fart bombs' are mixed in to the liquid polypropylene, the stuff that eventually forms the shock absorbent shell of the helmet.

As such, when the helmet develops small cracks the microcapsules rip open, discharging an odor strong enough to make you take notice. If a large crack occurs, the strength of the odor will be much stronger. You may even retch, which is more incentive not to crash.

"Cyclists often replace their helmets unnecessarily after dropping them on the ground, because they cannot tell whether they are damaged or not. The capsules eliminate this problem. If cracks form, smelly substances are released," explains Dr.-Ing. Christof Koplin, a research scientist at the Fraunhofer Institute.

So now Sally can sleep safe in the knowledge that her scalp isn't rotting; that obnoxious smell is just her helmet warning her it's time to get a new one.

Check out the Fraunhofer.de press statement for a more scientific rundown on the smelly helmet.