Mechanical energy harvesting: Advancements in piezoelectric nanogenerators

As science and technology grow at a rapid pace and human civilization progresses, portable microelectronic gadgets are becoming more and more commonplace. The energy sources of these devices have become a popular research. The most common and most available form of energy in the environment is mechanical energy derived from vibrations. The available energy density for random vibrations with frequencies ranging from hundreds of hertz to kHz is a few hundred microwatts to milliwatts per cubic centimeter. Therefore, how to capture this energy for battery charging, power supply for electronic devices, and remote/wireless sensing has become an important and novel research direction. Using nanoscale mechanical energy harvesting to power small circuits and create self-powered electronic devices has enormous potential, of which piezoelectric nanogenerators (PENGs) are widely studied. Piezoelectric nanogenerators, which use nanometer-scale piezoelectric materials to transforming arbitrary mechanical energy into electrical energy, are a rapidly emerging product category. They can produce sustained electrical energy and are more environmentally benign than chemical batteries. The concept and evolution of piezoelectric materials are first presented in this paper. Next, the structure and operation of a piezoelectric nanogenerator are explained. Lastly, the development trend of converting mechanical energy produced by drum vibration into electrical energy is combined.