Chin strap could be used to charge small devices
DOI: 10.1063/PT.5.028265
BBC : A chin strap made from a piezoelectric material generates electricity as wearers move their jaws. Designed by Aidin Delnavaz and Jeremie Voix of the École de Technologie Supérieure in Montreal, Canada, the proof-of-concept device can produce 18 µW of power after just 60 seconds of chewing. They say that to actually be useful, however, it will need to generate 20 times as much electricity, which could be achieved by simply increasing the amount of piezoelectric material in the strap. A 20-layer strap just 6 mm thick should be able to power an intelligent hearing protector, such as sound-canceling headphones that are used for communications in heavy industry or the military. It could also be used to power cochlear implants or other similar small electronics, but probably not anything as large as a smart phone.
