Piezoelectricity and Flexoelectricity from an Energy Harvesting Perspective: Nanogenerators

Energy harvesting is the process by which energy can be obtained from external sources and used for wearable electronics and wireless sensor networks. Piezoelectric nanogenerators are energy harvesting devices that convert mechanical energy into electric energy by using nanostructured materials. This article summarizes work to date on piezoelectric nanogenerators, starting with the basic theory of piezo- and flexo-electricity and moving through reports on nanogenerators using nanostructures, flexible substrates and alternative materials. A sufficient power generated from nanogenerators suggests feasible applications for either power sources or strain sensors of highly integrated nanodevices. Further improvements in nanogenerators holds promise for the development of self-powered implantable and wearable electronics.