Chinstrap harvests chewing energy for hearing aids

The Canadian inventors of an energy-harvesting chinstrap say it could enable hearing aids to be powered by chewing and talking.

Researchers from École de technologie supérieure (ÉTS) in Quebec created the chinstrap from piezoelectric fibre composites (PFC) that produce electricity as they are stretched.

They say the device could remove the need for batteries in a number of small-scale implantable or wearable electronic devices, such as hearing aids, cochlear implants, electronic hearing protectors and communication devices.

‘The only expensive part of the energy-harvesting device is the single PFC layer, which costs around $20,’ said Aidin Delnavaz, co-author of a paper on the chinstrap published in the Institute of Physics journal Smart Materials and Structures.

‘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. Additionally, the device could substantially decrease the environmental impact of batteries and bring more comfort to users.’

So far the device has only produced a very small amount of power – 10µW with the chinstrap worn in an optimum setup while the user chewed gum for 60 seconds.

‘Given that the average power available from chewing is around 7mW, we still have a long way to go before we perfect the performance of the device,’ said Delnavaz.

‘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 µW intelligent hearing protector.’

He added: ‘We will now look at ways to increase the number of piezoelectric elements in the chinstrap to supply the power that small electronic devices demand, and also develop an appropriate power management circuit so that a tiny, rechargeable battery can be integrated into the device.’