A Comparative Numerical Study on Piezoelectric Energy Harvester for Self-Powered Pacemaker Application

This study proposes the design of a micro-spiral-shaped piezoelectric energy harvester that scavenges energy from blood pressure variation in the cardiac cycle. The harvester can be a miniaturized perennial source of power that could even eliminate the need for replacement of conventional batteries used in current pacemaker technology. The concept of a 25 mu m thin spiral-based piezoelectric energy harvester with a diameter of 6 mm satisfying the dimensional constraints has been proposed. A number of lead-free materials have been used along with Pb[ZrxTi1-x]O-3 (PZT-5A) to compare the performance. The harvester has been designed in such a way that the natural frequency of the structure remains in the range of 1.1-1.3 Hz, which is equivalent to 66-78 heart beats min(-1) of humans. The obtained alternating electric current from piezoelectric materials is converted into direct current. The maximum open-circuit voltage obtained is approximate to 0.9 V, which is not sufficient for charging a pacemaker battery. Therefore, boost converter circuit is employed to step up the voltage. It is found that K0.475Na0.475Li0.05(Nb0.92Ta0.05Sb0.03)O-3 (KNLNTS) has the best performance as compared to other materials under study. The boosted voltage obtained from KNLNTS is approximate to 6 and approximate to 7 V for 80 and 90% duty cycle, respectively, which are sufficient for pacemaker battery charging.