Pendulum-based vibration energy harvesting: Mechanisms, transducer integration, and applications

Vibration energy harvesting is a promising approach to provide wireless sensors and portable electronics with sustainable power by converting ambient kinetic energy into expected electrical energy. As one of the most fundamental mechanical oscillators, pendulums are restored by gravity rather than elastic elements and have drawn a number of research interests in developing vibration energy harvesters in recent years due to their simple and reliable structures. This paper comprehensively reviews the state-of-the-art progress of the pendulumbased energy harvesting. The pendulum mechanisms for energy harvesting such as single-pendulum configurations, multi-pendulum configurations, and pendulums with modulation mechanisms are elaborated and discussed. The integrations of electromagnetic, piezoelectric, triboelectric, and hybrid transducers are characterized and compared. The applications of the pendulums in harvesting energy from ocean wave, vehicle motion, human motion, structural vibration, and flow-induced vibration are reviewed. Finally, the challenging issues and future trends of this technology are summarized based on the progress to date.