Droplet-Based Electricity Generator toward Practicality: Configuration, Optimization, and Hybrid Integration

Electricity is the basic and essential need for every single person and guarantees the development of society, industry, and the economy. The limited conventional fossil fuel meets the challenge of the sharply increasing demand, while may lead to severe pollution. Emerging green energy harvesting systems can convert ambient kinetic, thermal, and solar energy to electricity effectivity. In this review paper, the authors provide an overview of the new and emerging methods, droplet-based electricity generators, that convert energy from the ubiquitously existing water droplets. The authors begin with a brief introduction of the working principle for droplet-based power generators. Existing configurations of the droplet-based power generator are also summarized, including 1) single electrode, 2) transistor-based, and 3) direct current generator. Then, a detailed discussion of the design and operation factors that may impact the energy harvesting efficiency of droplet-based power generators is provided. Hybrid energy harvester that integrates droplet-based power generators with other triboelectric, pyroelectric, and photovoltaic-based devices are summarized. Finally, challenges and perspectives regarding the future development of droplet-based power generators are described. The reviews demonstrate a highly efficient method for energy harvesting from water droplets to meet the vital needs of the energy crisis.