Research using a prototype piezoelectric energy-harvesting device developed by the University of Michigan suggests that the human heart provides more than enough energy to power a pacemaker, according to a statement released by the American Heart Association. The research has led to fresh speculation that piezoelectricity, electricity converted from mechanical stresses undergone by a generator, may one day provide an alternative to battery-powered pacemakers that need to be surgically replaced as often as every five years.

Though news reports have suggested that the prototype has harvested energy directly from the human heart, the small print of the American Heart Association's statement suggests otherwise. Though its introductory remarks describe an "experimental device that converts energy from a beating heart," it goes on to say, in its brief description of the methods used, that:

"Researchers measured heartbeat-induced vibrations in the chest. Then, they used a 'shaker' to reproduce the vibrations in the laboratory and connected it to a prototype cardiac energy harvester they developed. Measurements of the prototype's performance, based on sets of 100 simulated heartbeats at various heart rates, showed the energy harvester performed as the scientists had predicted – generating more than 10 times the power than modern pacemakers require."

So rather than hooking the device up to a human heart, the researchers instead measured the kinetic energy made available by the heart, and then recreated those energy levels using shakers from which the prototype drew power.

Thanks to its nonlinear energy harvesting, the research suggests that the prototype could draw sufficient energy from the heart at pulse rates of anywhere between 20 and 600 beats per minute. It's claimed that, unlike battery-powered pacemakers, the device is not affected by electromagnetic interference from devices such as mobile phones.

The distinction between a heart-powered prototype and a prototype made to run from equivalent power levels is an important one, and the American Heart Association statement describes implants as the next step, though the research to date is described as preliminary. Though the statement provides no details on the prototype's inner workings, it's worth bearing in mind that functionally-similar prototypes have been developed in the past: a reminder that progress almost always occurs in fractional increments.

There are more details of the research in the University of Michiganvideo below.