This course focuses on the transformation of mechanical energy into low-power electricity with an emphasis on vibration-based energy harvesting. A primary goal is to describe the methods of mechanical energy harvesting to use in low-power sensors. Piezoelectric, electromagnetic, electrostatic and magnetostrictive conversion mechanisms will be discussed along with the use of electroactive polymers. Special focus will be placed on piezoelectric materials due to their substantially large power density and ease of application at different geometric scales. System-level modeling and analysis, power density levels, storage devices, deterministic and random energy harvesting, kinetic energy harvesting, flow energy harvesting from aeroelastic and hydroelastic vibrations, acoustic energy harvesting and nonlinear energy harvesting for frequency bandwidth enhancement will be addressed.

Energy harvesting from dynamical systems offers the possibility of enabling self-powered wireless electronic components, such as low-power sensors in a plethora of current and future applications of the Internet of Things, from wearable electronics to civil structures. Piezoelectric energy harvesting is arguably the most popular method in this context. This course will cover methods of piezoelectric energy harvesting with examples from two decades of literature. Following a brief review of the basic concepts and lumped-parameter electromechanical representation, the standard problem of vibration-based energy harvesting using piezoelectric transduction will be discussed for AC and DC power generation scenarios. The extension of such lumped-parameter approaches to distributed-parameter systems will also be summarized. Performance and bandwidth enhancement in piezoelectric energy harvesting by leveraging intentionally introduced nonlinearities will be covered next. Specifically, monostable and bistable Duffing oscillator configurations will be reviewed with various examples from the literature, along with select modeling techniques, such as the use of the method of harmonic balance. Inherent material and dissipative nonlinearities, as well as circuit nonlinearities, will also be summarized. Aeroelastic and hydroelastic energy harvesting techniques will be reviewed for converting fluid flow into electricity. Examples will be detailed on leveraging the classical flutter and axial flow-induced nonlinear limit cycle oscillations. Finally, recent developments in the domain of exploiting metamaterial and phononic crystal concepts in energy harvesting will be addressed with select examples of energy harvesting combined with structure-borne elastic wave focusing and bulk acoustic wave focusing, as well as with locally resonant metamaterials.