American researchers have tested an experimental device that can use energy from a beating heart to produce electricity.
Findings from the study were presented at the American Heart Association’s Scientific Sessions 2012.
M Amin Karami, lead author of the study and research fellow in the Department of Aerospace Engineering at the University of Michigan, said the energy-harvesting approach is a promising technological solution for pacemakers, because they require only small amounts of power to operate - typically around 1μW[microwatt, Greek mu].
The battery accounts for around 60 per cent of a pacemaker’s size, Karami said, and it lasts for five to seven years.
“A mechanism that could continuously generate 1μW[microwatt, Greek mu] would free a lot of space,” he remarked, “and it would never deplete. It could stay there for as long as it worked.”
He pointed out that many of the patients are children who live with pacemakers for many years.
“You can imagine how many operations they would be spared if this new technology is implemented.”
As part of their study, the team of two engineers and a doctor measured measured heartbeat-induced vibrations in the chest.
Then they reproduced these vibrations using a laboratory instrument and connected it to a prototype cardiac energy harvester they developed, which produces an electrical output from structural vibrations in a ‘smart’ material.
Measurements based on simulations 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.
They have also carried out animal experiments which confirmed that a harvester in close vicinity to the heart could produce enough power - but they have not yet proved that it would work in the usual pacemaker location under the skin near the collarbone, with fine wires running to the heart.
They are investigating that now, as well as considering alternative implant sites.
The next step will be integrating the energy harvester, which is about half the size of batteries now used, into the pacemaker can.
The concept is proved, but the cycle of prototyping, safety testing and development for production means that commercial deployment is still some way off.
The study’s co-authors with Karami are David J Bradley and Daniel J Inman.