All-Electrospun Piezoelectric Energy Harvesting for Leadless Pacemakers

Leadless pacemakers are an emerging implantable medical device technology that improves patient outcomes through miniaturization; however, these devices still need to be replaced due to battery depletion, creating additional risk due to surgery. With energy harvesting, the lifetime of a battery may be extended. Latest research has investigated the use of harvesting devices that replace the bulk of the pacemaker's inner electronics and battery. Integrating the energy harvesting element with the current leadless pacemaker becomes more challenging due to this factor. Positioning the energy harvesting element on the outer shell of the leadless pacemaker would mitigate interference with the inner electronics and potentially enable a more seamless integration of the device. We hypothesize that a piezoelectric outer layer on an implanted leadless pacemaker can harvest energy from the heart's motion due to heart tissue contracting around the device during systole. We fabricated an all-electron energy harvesting device with piezoelectric and conductive nanofibers as a coating for a leadless pacemaker. A drop treatment step is investigated for improving material properties and its effect on the energy harvesting output. The final device was characterized in vitro with a custom-built simulated heart contraction test and in vivo with animal studies. This resulted in a highly scalable method to fabricate an energy harvesting device on a leadless pacemaker, as well as a system for evaluating energy harvesting performance from simulated squeezing of heart tissue. We observed a voltage output of up to 60 mV(pp) (peak-to-peak) in a swine's heart, and device performance was shown experimentally to be mainly affected by relative motion, such as an increased heart rate and movement within the ventricle. The strategy demonstrated the seamless coupling of a leadless pacemaker with a scalable piezoelectric energy harvesting device and presented a potential solution for powering various implantable medical devices.