Supervisor:
Alireza Rezaniakolaei

Co-Supervisor:
Sam Riahi and Majid Khazaee

Assessment Committee:
Kaiyuan Lu (Chair)
Hamideh Khanbareh, Department of Mechanical Engineering, University of Bath, UK
Ayech Benjeddou, ISAE-SUPMECA, France

Moderator:
Kaiyuan Lu

Abstract:

Cardiac motion–driven energy harvesting for intracardiac implants offers a pathway toward self-powered leadless pacemakers that are no longer limited by battery life or replacement surgeries. This thesis develops an integrated framework that spans cardiac motion characterization, piezoelectric harvester design, and long-term durability assessment. 

 

Three complementary approaches are used to quantify heart kinematics: in-vivo measurements with a miniaturized 9-degree-of-freedom motion sensor in a porcine model, cardiac MRI–based wall motion analysis in a human subject, and a high-fidelity electromechanical heart model incorporating anatomy, fiber orientation, electrophysiology, and fluid–structure interaction. From these data, kinematic criteria are formulated to predict energy-harvesting potential across candidate implant locations, consistently identifying the most promising and clinically feasible site for a self-powered pacemaker.

To address the mismatch between low-frequency cardiac motion and the high natural frequency of piezoelectric energy harvesters, the thesis proposes an impact-based four-point bending configuration. This design achieves a significant increase in energy conversion efficiency and normalized output energy compared with conventional cantilever harvesters. A micro-scale electromechanical model of the impact region reveals that a localized high-strain zone dominates power generation and shows that minimizing passive piezoelectric areas can markedly enhance output. 

The durability of the energy harvester is examined through a long-term bench test simulating more than 35 million cardiac cycles, which reveals mechanical degradation of the silver electrode as the principal cause of voltage decay, while the piezoelectric material remains intact. Based on this mechanism, practical design and material strategies are proposed to improve long-term reliability. Overall, the work demonstrates that impact-based, durability-aware harvesters can serve as the basis for clinically viable, battery-free leadless pacemakers.