Bicycle helmets can only protect people's heads if they are completely undamaged. But how can you tell whether dropping your helmet a few times is enough to compromise its safety? If Christof Koplin and other scientists at the Fraunhofer Institute have their way, you’ll be able to smell the difference.
The researchers placed bad-smelling oils within microcapsules. These tiny capules, each no more than 50 micrometers long, are sealed within a layer of melamine formaldehyde resin and then embedded within the polypropylene portion of the helmet. The resin prevents the capsules from rupturing during the manufacturing process or minor wear and tear. If the helmet is structurally damaged, however, they begin to break. The worse the damage, the worse the resulting smell.
Apart from helmets, the researchers envision using their smell detection system in otherwise inaccessible hoses and pipes.
The damaged helmet releases odoriferous substances. Bottom right: the opened microcapsule.
Credit: © Fraunhofer IWM