Fraunhofer Lab Engineers a Cycling Helmet That Raises a Stink When it Needs Replacing

This Helmet Stinks

When the protective plastics in this cycling helmet are damaged, they release odoriferous compounds that alert the user that it's time to get a new helmet.Fraunhofer IWM

Cycling helmets serve but one singular purpose: protecting your cranium when speed and gravity conspire against your cycling prowess. But a helmet that's damaged -- even slightly damaged -- can fail when you need it the most. Compounding the problem is the fact that it's very hard to detect hairline cracks or other flaws in a cycling helmet that result from routine wear and tear. That's why researchers at Germany's Fraunhofer Institute have engineered the first bicycle helmet that literally makes a stink when it becomes damaged.

Materials scientists at Fraunhofer have developed a new polymer that contains tiny microcapsules containing odoriferous oils that crack open when the polymer's surface is the slightest bit compromised. The smell then alerts the user that it's time to get a new helmet -- and might even compel him or her to do so, since their old helmet is no longer pleasant to be around.

The engineers designed the microcapsules to range from one micrometer to 50 micrometers thick, then used computer simulations to determine exactly how many capsules need to be added to the plastic. A tiny fracture might smell just enough to let you know the helmet has a hairline crack but is still within the safety range. A larger flaw in the plastic elicits a stronger stench, letting riders know it's seriously time to get a new helmet.

The technology isn't just applicable to helmets, though since the microcapsules work well with plastics it's a good place to start. Fraunhofer envisions their olfactory tech going into pressure hoses, gas pipes, water pipes and other materials that, when damaged, could lead to unpleasant situations. More unpleasant than a nasty stench, that is.