Piezoelectric Nanogenerators for Mechanical Energy Harvesting

摘要

Piezoelectric ZnO nanowires (NWs) have recently been demonstrated as a promising concept to harvest micro- andnano-scale mechanical energy from the surroundings. It is named nanogenerator. The operation principle relies onthe bending of NWs by an external disturbance which creates piezoelectric potential along the deformed surfaces.The piezoelectric potential was predicted to be hundreds of milivolts per NW and the optimal power output per NWcould reach a few nanowatts when it is under resonant oscillation. The first nanogenerator prototype was fabricatedwith vertically aligned ZnO NW arrays that were placed beneath a zigzag-shaped metal electrode with a small gap.In this design, all the NWs can be actuated simultaneously and continuously by ultrasonic waves, leading to theproduction of a continuous DC current. A textile fiber based nanogenerator has been developed for harvesting lowfrequencyvibration/friction energies. A piezoelectric thin film based nanogenerator was demonstrated to convertlow-speed wind energy into electricity through the stimulated oscillation. These devices have the potential tofundamentally improve the mechanical energy harvesting capability with advanced nanostructure building blocksand compact designs, which might eventually lead to an effective power source for self-powered electronic systemswith higher energy density, higher efficiency, longer life time, as well as lower cost.