Piezoelectric Energy Harvesting for Pacemaker Applications: Current State-of-the-Art, Materials, Design, and Alternative Technologies

Implantable cardiac pacemakers are small medical devices surgically inserted into the chest to control abnormal heart rhythms. At present, commercial pacemakers are battery-operated and lack a self-charging mechanism. Utilizing a self-powered pacemaker can extend their functional lifespan inside the body and reduce the need for high-risk repeat surgeries. Thus, human energy harvesting is regarded as a potential solution to the challenges, by which effectively capturing the heart's complex movements could significantly enhance energy harvesting opportunities. The piezoelectric-based energy harvesting technique presents a promising option for converting biomechanical energy into electrical energy, offering high energy densities. Herein, this review paper introduces the concept of piezoelectricity, followed by a detailed discussion on piezoelectric-based pacemakers; this includes an investigation of piezoelectric materials for improved flexibility, stretchability, biocompatibility, higher power output, and in vivo application and testing. A brief discussion comparing piezoelectric-based pacemakers with alternate energy harvester-based pacemakers is presented. Additionally, current challenges, plausible solutions, and future perspectives are also discussed.