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Bites of energy: Chewing powers PFC chinstrap

Posted: 23 Sep 2014 ?? ?Print Version ?Bookmark and Share

Keywords:chinstrap? clean energy? piezoelectric fibre composites?

The newest source of clean energy could be your own jaw. Researchers from the Sonomax-?TS Industrial Research Chair in In-ear Technologies (CRITIAS) at ?cole de technologie suprieure (?TS) in Canada have created an energy harvesting chinstrap made from piezoelectric fibre composites (PFC).

The researchers hope that the device will be able to generate electricity from eating, chewing and talking, and power a number of small-scale implantable or wearable electronic devices, such as hearing aids, cochlear implants, electronic hearing protectors and communication devices.

Jaw movements have proved to be one of the most promising candidates for generating electricity from human body movements, with researchers estimating that an average of around 7mW of power could be generated from chewing during meals alone.

PFC is a type of piezoelectric smart material that consists of integrated electrodes and an adhesive polymer matrix. The material is able to produce an electric charge when it stretches and is subjected to mechanical stress.

In their study, the researchers created an energy-harvesting chinstrap made from a single layer of PFC and attached it to a pair of earmuffs using a pair of elastic side straps. To ensure maximum performance, the chinstrap was fitted snugly to the user, so when the users jaw moved it caused the strap to stretch.


To test the performance of the device, the subject was asked to chew gum for 60 seconds while wearing the device; at the same time the researchers recorded a number of different parameters.

The maximum amount of power that could be harvested from the jaw movements was around 18 W, but taking into account the optimum set-up for the head-mounted device, the power output was around 10 W.

"The power level we achieved is hardly sufficient for powering electrical devices at the moment; however, we can multiply the power output by adding more PFC layers to the chinstrap. For example, 20 PFC layers, with a total thickness of 6 mm, would be able to power a 200 W intelligent hearing protector," said Aidin Delnavaz, co-author of the study.

One additional motivation for pursuing this area of research is the desire to curb the current dependency on batteries, which are not only expensive to replace but also damaging to the environment if they are not disposed of properly.

The single PFC layer used in the device costs around $20.

"Considering the price and short lifetime of batteries, we estimate that a self-powered hearing protector based on the proposed chinstrap energy-harvesting device will start to pay back the investment after three years of use," continued Delnavaz.

The first results of the device's performance have been published in IOP Publishings journal Smart Materials and Structures.

- Paul Buckley
??EE Times Europe

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