Piezo-rubber promises to breathe new life into portable power

A new nanotechnology that merges rubber with miniscule ribbons could enable us to use our lungs and feet to power mobile phones in the future, according to a team of researchers.

Michael McAlpine of Princeton University's Department of Mechanical and Aerospace Engineering led a research effort to create piezoelectric materials that harvest energy from the human body.

He hopes that the materials, which convert physical pressure into electricity, could be used to convert the energy from the movement of our lungs during breathing into electricity that could be consumed by portable electronic devices.

The energy produced by a heel strike when walking could also be a rich source of electricity, according to the paper, which is published in Nano Letters, a monthly journal produced by the American Chemical Society.

Piezoelectric energy harvesting has been a holy grail for environmentally aware architects and mobile electronics companies for some years. Applications have been suggested including backpacks for the military, which bounce up and down as soldiers run, and help to power electrical equipment such as radios used in the field.

Architects have also experimented with piezoelectric steps that harvest the energy from footfalls to power LED lighting systems, while a number of trials are under way including an installation on the Tokyo subway system and a piezoelectric dance floor at a Dutch nightclub.

However, the materials have always been problematic in terms of efficiency. But the application of nano materials could change that and tip the balance, especially as portable electronic devices continue to reduce their power consumption.

The Princeton research team is now producing nano-sized ribbons of lead zirconate titanate, and is affixing them to ribbons of flexible silicone rubber. The result is a thin "piezo-rubber" that could convert 80 per cent of kinetic energy into electrical energy.

According to the paper, breathing can generate up to 1W of power, which could be used to help extend the life of an implantable surgical device such as a pacemaker battery.