Energy From a Beating Heart to Power a Pacemaker: Study

A team of U.S. researchers have come up with a new device that harnesses energy from a beating heart to keep a pacemaker running. This new finding will help patients to power their pacemakers and do away with the need to replace batteries every few years.

According to Dr. M. Amin Karami, Ph.D., who is also a research fellow in the Department of Aerospace Engineering at the University of Michigan in Ann Arbor, preliminary studies used piezoelectricity to charge the device. Piezoelectricity refers to the charge that is accumulated in certain solid materials in response to applied mechanical stress.

Dr. Karami believes that this method is a promising technological solution for pacemakers, because they require only small amounts of power to operate. This kind of electricity can be efficiently used in other implantable cardiac devices like defibrillators, which also have minimal energy needs.

The pacemakers used currently demands a replacement every five to seven years which proves to be costly and inconvenient.

"Many of the patients are children who live with pacemakers for many years," he said. "You can imagine how many operations they are spared if this new technology is implemented."

For this study, the researchers measured heartbeat-induced vibrations in the chest. With the help of a shaker they reproduced the vibrations in the laboratory and then 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.

The researchers then moved to implanting the energy harvester, which is about half the size of batteries that is now used in pacemakers. They hope to integrate their technology into commercial pacemakers.

Linear and non linear are the two types of energy harvesters that power a typical pacemaker. Linear harvesters work well only at a specific heart rate, so heart rate changes prevent them from harvesting enough power. Whereas a non linear harvester uses magnets to enhance power production and make the harvester less sensitive to heart rate changes. The nonlinear harvester generated enough power from heartbeats ranging from 20 to 600 beats per minute to continuously power a pacemaker. Even in this study the researchers have used the non linear method.

According to Karami, devices such as cell phones or microwave ovens would not affect the nonlinear device.

This study was presented at the American Heart Association's Scientific Sessions 2012.