nanogenerator

A nanogenerator is a compact device that converts mechanical or thermal energy into electricity, serving to harvest energy for small, wireless autonomous devices. It uses ambient energy sources like solar, wind, thermal differentials, and kinetic energy. Nanogenerators can use ambient background energy in the environment, such as temperature gradients from machinery operation, electromagnetic energy, or even vibrations from motions.

Energy harvesting from the environment has a very long history, dating back to early devices such as watermills, windmills and later hydroelectric plants. More recently there has been interest in smaller systems. While there was some work in the 1980s on implantable piezoelectric devices, more devices were developed in the 1990s including ones based upon the piezoelectric effect, electrostatic forces, thermoelectric effect and electromagnetic induction—see Beeby et al for a 2006 review. Very early on it was recognized that these could use energy sources such as from walking in shoes, and could have important medical applications, be used for in vivo MEMS devices or be used to power wearable computing. Many more recent systems have built onto this work, for instance triboelectric generators, bistable systems, pyroelectric materials and continuing work on piezoelectric systems as well as those described in more general overviews including applications in wireless electronic devices and other areas.