Mechanical Energy Harvesting Using Wurtzite Nanowires

This chapter reviews a novel technology that uses piezoelectric nanowires to harvest nanoscale mechanical energy. Wurtzite ZnO nanowires were first applied for this purpose. Due to the bending of nanowires, the piezoelectric effect induces positive and negative potentials on the stretched surface and compressed surface, respectively. This effect has been proved by using a conductive AFM tip to deflect individual wurtzite ZnO and CdS nanowires as well as vertically aligned ZnO nanowire arrays. On the basis of this phenomenon, a prototype nanodevice (nanogenerator) has been successfully developed to convert ultrasonic wave energy into electricity. After optimization, the nanogenerator’s output has reached ∼83 nW/cm², which shows a great potential to power nanosensors. A flexible substrate and textile fibers were also integrated with the ZnO nanowire array for harvesting energy from low-frequency perturbations. At the end of this chapter, several pathways are suggested for further performance improvements.