Harvesting Vibration and Ultrasound Energy by Triboelectric Nanogenerators

Harvesting vibration and ultrasound energy are a growing research field in which various working mechanisms, material designs, and structures have been developed for powering electronic devices or developing self-powered sensors. The TENGs have gained significant attention from the perspectives of competitive characteristics, including high output, simple structure, and compact size. This chapter describes the historical and current state-of-the-art progress of TENGs with the purpose of providing a comprehensive introduction and future perspectives. Adapted working mechanisms are necessary for successful energy harvesting based on the frequency of mechanical vibrations. Accordingly, optimized material designs and structures should be independently investigated for each frequency range. Thus, a strategic roadmap and milestone to develop optimal TENGs distinguished by frequency range are needed. In this regard, herein, we look at the investigation of two categories of vibration energy harvesting: vibration energy harvesting for low-frequency mechanical motions and ultrasound energy harvesting mediated by high-frequency ultrasound. We especially describe current progress in ultrasound energy harvesting, focusing on an in-depth introduction of its working mechanisms and fundamental studies. It is a recent innovative technology that can transfer energy to implantable medical devices (IMDs) mediated by biosafe ultrasound. We believe that this chapter can help readers to understand the significance and potential of harvesting vibrational energies based on triboelectricity and therefore raise attention to them to encourage massive participation of worldwide researchers in various areas.