Nanogenerator

A nanogenerator is a small device that converts mechanical or thermal energy into electricity. It is an energy harvesting device where energy from external sources (e.g., solar power, thermal energy, wind energy, salinity gradients, and kinetic energy), also known as ambient energy, is converted into electricity for use by small, wireless autonomous devices like those used in wearable electronics, condition monitoring, and wireless sensor networks. Energy harvesters usually provide a very small amount of power for low-energy electronics. While the input fuel for some large-scale energy generation costs resources (oil, coal, etc.), the energy source for energy harvesters is present as ambient background. For example, temperature gradients exist from the operation of a combustion engine, and in urban areas, there is a large amount of electromagnetic energy in the environment due to radio and television broadcasting, and energy can be harvested from the vibrations during walking. There are three classes of nanogenerators: piezoelectric, triboelectric, both of which convert mechanical energy into electricity, and pyroelectric nanogenerators, which convert heat energy into electricity. A piezoelectric nanogenerator is an energy-harvesting device capable of converting external kinetic energy into electrical energy via action by a nano-structured piezoelectric material. It is generally used to indicate kinetic energy harvesting devices utilizing nano-scaled piezoelectric material, like in thin-film bulk acoustic resonators. The working principle of the nanogenerator will be explained in two different cases: the force exerted perpendicular to and parallel to the axis of the nanowire. The working principle for the first case is explained by a vertically grown nanowire subjected to a laterally moving tip. When a piezoelectric structure is subjected to the external force of the moving tip, deformation occurs throughout the structure.