Harvesting Vibration Energy

Vibration is one of the most common mechanical agitations in our living environment, ranging from human motions, automobiles, machines and even water waves. Harvesting energy from vibrations to power up electronic devices can be beneficial for health care, infrastructure monitoring, environmental protection and security. The state-of-the-art mechanisms of vibrational energy harvesting are limited to transductions based on piezoelectric effect, electromagnetic effect, electrostatic effect and magnetostrictive effect. All of the mechanisms require energy harvesting devices to operate at or within a very narrow range around resonance frequency. However, majority of the ambient vibrations have a wide distribution of frequency spectrum, which may even drift over time, making the conventional mechanisms unsuitable under most circumstances. This chapter presents the approaches that have been developed using TENG for harvesting vibration energy with examples demonstrated based on machine vibration, human activities and sound waves. The major technical approach is using the contact-separation mode TENG. A highlight is about harvesting of sound wave energy using TENG, which is rather challenging to be fulfilled by other techniques.