**Preface to "Energy Harvesters and Self-powered Sensors for Smart Electronics"**

Recently, we have witnessed the revolutionary innovation and flourishing advancement of the Internet of Things (IoT), which will maintain a strong momentum even more with the gradual rollout of the fifth generation (5G) wireless network and the rapid development of personal healthcare electronics. Enabled by the ultrahigh data communication rate of 5G technology, various IoT systems can be envisioned by linking numerous multifunctional electronic devices together in an integrated and interconnected network, such as in smart homes, smart buildings, industry 4.0, smart cities, unmanned shops, wearable body area networks, point-of-care diagnosis and treatment, etc. In these complicated systems with widely distributed device nodes, the energy supply in the IoT era is gradually migrating from the regularly replaced battery-based supply mode toward the sustainable in situ supply mode. Compared to batteries, energy harvesting technologies that scavenge available energies from the ambient surroundings exhibit great merits in supplying energy to IoT systems, e.g., highly extended and unlimited lifetime, great portability, flexible/stretchable compatibility, and sustainability. Therefore, various energy harvesting technologies and devices are undergoing rapid and significant innovation, providing key functionalities in diverse IoT systems as energy harvesters and/or self-powered sensors. Accordingly, this book showcases one editorial and nine research articles that focus on the novel development of energy harvesters/self-powered sensors and their broad applications in IoT systems and smart electronics. The research articles explore the following aspects of energy harvesting technologies, such as electromagnetic energy harvesters, piezoelectric energy harvesters, and hybrid energy harvesters: mechanism design, structural optimization, performance improvement, and a wide range of energy harvesting and self-powered monitoring applications.

We would like to express our sincere appreciation to all the authors for contributing their papers to this Special Issue Book. Meanwhile, we would also like to thank all the reviewers for dedicating their valuable time and helping to ensure the quality of this Special Issue Book.

> **Qiongfeng Shi, Huicong Liu** *Editors*
