Capturing the Body’s Energy

Researchers from universities in the U.S. and China have developed a microscopic device capable of producing power from the body’s organs, such devices in turn can be used to power other implanted biomedical devices, like pacemakers, heart-rate monitors and neural stimulators, eliminating the need for invasive surgeries to replace their batteries.

A group led by John Rogers at the University of Illinois has developed a flexible, piezoelectric patch that harvests the mechanical energy of a beating heart. The implant contains a film made of lead zirconate titanate (PZT) surrounded by gold and platinum electrodes. PZT is piezoelectric, meaning a voltage develops across it when it is bent. The output is used to charge a tiny battery integrated into the device, and the entire system is encased in a layer of polyimide to make it bio-compatible.

The researchers tested their device with both experiments and computer simulations. During experiments, they implanted the device on the hearts of cows and sheep and they found that the device operated at an efficiency of 2 per cent.

Implanted devices like cardiac pacemakers need about 1 microwatt to function, and last for some 10 years. Currently, such devices come with a built-in cell that produces this power, and requires replacement after the lifetime period. Stacking five of the PZT energy harvesters on an organ results a power-density of 1.2 microwatt/cm, sufficient to operate a pacemaker.

[Photo Credit: University of Illinois and University of Arizona]