ZnO and PZT Thin Film Piezoelectric MEMS Vibrational Energy Harvesters for Cardiac Pacemaker

MEMS piezoelectric energy harvesters (PEHs) have potential to convert mechanical energy of human heart vibrations into electrical energy to power the pacemaker. Challenges exist to match the resonant frequency of PEHs to heart wall low vibrational frequency and the pacemaker size constraint to fit the PEH. Moreover, the output performance of PEH with hybrid piezoelectric materials is not studied in literature. This work aims to design a MEMS PEH element with a resonant frequency <50 Hz, an output voltage of 2.5–2.8 V, a dimension of 40 mm by 6 mm, and optimise its output performance via a hybrid of ZnO and PZT. Correlation studies between the PEH design and output performance were performed to derive design strategies. The split-cantilever energy harvester (SCEH) structure was built using COMSOL Multiphysics. SCEH has resonant frequencies at 3.1 Hz and 4.9 Hz, with voltages of 36.21 V and 38 V respectively. The simulation results successfully meet the requirements for powering the pacemaker in terms of dimensions, resonant frequency, and generated voltage.