Over the past few decades, cardiac pacemaker technology has improved to the point that pacemakers have become a commonplace medical implant that have helped improve or save the lives of many millions of people around the world. Unfortunately, the battery technology used to power these devices has not kept pace and the batteries need to be replaced on average every seven years, which requires further surgery. To address this problem, a group of researchers from Korea Advanced Institute of Science and Technology (KAIST) has developed a cardiac pacemaker that is powered semi-permanently by harnessing energy from the body's own muscles.
The research team, headed by Professor Keon Jae Lee of KAIST and Professor Boyoung Joung, M.D. at Severance Hospital of Yonsei University, has created a flexible piezoelectric nanogenerator that has been used to directly stimulate the heart of a live rat using electrical energy produced from small body movements of the animal.
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Based on earlier experiments with this technology used by KAIST to produce a low-cost, large area version, the team created their new high-performance flexible nanogenerator from a thin film semiconductor material. In this case, lead magnesium niobate-lead titanate (PMN-PT) was used rather than the graphene oxide and carbon nanotubes of previous versions. As a result, the new device was able to harvest up to 8.2 V and 0.22 mA of electrical energy as a result of small flexing motions of the nanogenerator. The resultant voltage and current generated in this way were of sufficient levels to stimulate the rat's heart directly.
The direct benefit of this experimental technology could be in the production and use of self-powered flexible energy generators that could increase the life of cardiac pacemakers, reduce the risks associated with repeated surgeries to replace pacemaker batteries, and even provide a way to power other implanted medical monitoring devices.
"For clinical purposes, the current achievement will benefit the development of self-powered cardiac pacemakers as well as prevent heart attacks via the real-time diagnosis of heart arrhythmia," said Professor Keon Jae Lee. "In addition, the flexible piezoelectric nanogenerator could also be utilized as an electrical source for various implantable medical devices."
Other self-powering experimental technologies for cardiac pacemakers have sought to provide energy from the beating of the heart itself, or from external sources, such as in light-controlled non-viral optogenetics. But the KAIST pacemaker appears to be the first practical version to demonstrate real promise in living laboratory animals and, with any luck, offer a significant improvement to cardiac pacemaker technology for human patients in the not-too-distant future.
This team's research was published in the journal Advanced Materials.
The video below shows the flexible piezoelectric nanogenerator in action.