Earlier this year, Canadian engineer Aidin Delnavaz placed a pair of industrial earmuffs on his head, adjusted a special strap beneath his chin, and waited for the material to start harvesting energy while he chewed gum for two minutes. He only generated a small amount of wattage, but it was enough for the researchers to conclude that wearing the chin strap for the duration of a meal could power a small hearing aid for two hours.
Delnavaz and his École de Technologie Superieure colleague Jérémie Voix had proved their hypothesis: The latest renewable resource could be your jaw.
Mouth power, they acknowledge in a paper in the journal Smart Materials and Structures, is pretty limited. The chin strap wouldn’t be able to charge anything much larger than a very small device, and it comes with some serious headgear. “Actually, the device is really comfortable,” Delnavaz insists. The strap doesn’t necessarily have to be tight to harvest energy, he adds. The way Delnavaz and Voix envision it, whoever is wearing the chin strap would already be sporting a helmet. Think of a firefighter, for example, who needs power for his bluetooth headset. Or soldiers using a military version of Google Glass.
The key ingredient of the operation is a smart material called piezoelectric fiber composites (PFC), which can be aligned on a thin foil that’s then glued to the chin strap. PFC is most often used as a sensor, but Delnavaz and Voix showed how it can be used as an energy converter, too. In theory, the more layers of PFC you add to the chin strap, the more powerful the tool can become.
But what happens if you spill soup on yourself, or drool? Will you get electrocuted and die? “No,” Voix says. “The chances are really little, because the fibers are really not in contact with your skin. And plus they’re protected by an electrode, and on top of that they’re protected by a strap.”
Good to know. But even though the chin strap looks silly, Voix makes a good point about how devices like the chin strap could play important roles in a decentralized energy strategy of the future. “I think that sooner rather than later consumers will request that our devices are autonomous and self-powered,” Voix says. “And that way, you’re not filling up landfill with batteries and cables.”