The global energy crisis and environmental pollutions caused mainly by the increased consumption of nonrenewable energy sources prompted researchers to explore alternative energy technologies that can harvest energies available in the ambient environment. Mechanical energy is the most ubiquitous ambient energy.Piezoelectric transduction is the prominent mechanical energy harvesting mechanism, Thus, piezoelectric energy harvesting has received the utmost interest by the scientific community.Advancements of micro and nanoscale materials and manufacturing processes have enabled the fabrication of piezoelectric generators.

Among all the ambient energy sources, mechanical energy is the most ubiquitous energy that can be captured and converted into useful electric power. Piezoelectric energy harvesting is a very convenient mechanism for capturing ambient mechanical energy and converting it into electric power since the piezoelectric effect is solely based on the intrinsic polarization of the material and it does not require a separate voltage source, magnetic field, or contact with another material as in the case of electrostatic, electromagnetic, and triboelectric energy harvesting, respectively. A number of piezoelectric materials such as single crystals, ceramics, polymers, composites, and bio-inspired materials have been prepared in the form of the nanostructure, thin-film, and layer stacks for building piezoelectric generators to be deployed in a number of fields. The prominent field of application of piezoelectric generators is the wireless sensor networks. The continuous increase in the number of sensor nodes deployed in diverse fields and the significant reduction of node size and power requirement made it convenient to harvest ambient energy for sustainable power supply to the sensor nodes. Transportation, avionics, defense, infrastructure, environmental monitoring, networking, electronics, healthcare, and many other industries are the potential field of application of piezoelectric energy harvesters.

Figure 1. The advancements, limitations, and improvements of the materials and applications of the piezoelectric energy harvesting technology.

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www.sciencedirect.com/science/article/pii/S2211285520311411#bib19