The new field of nanopiezotronics

Semiconducting and piezoelectric nanowires and nanobelts have exciting applications in electronics, optoelectronics, sensors, and the biological sciences. We review the use of ZnO nanowires and nanobelts in electromechanical coupled devices. A nanogenerator that uses aligned ZnO nanowires for converting nanoscale mechanical energy into electric energy is described. The mechanism of the nanogenerator relies on the unique coupling of ZnO's piezoelectric and semiconducting properties. The approach has the potential to convert biological mechanical energy, acoustic/ultrasonic vibration energy, and biofluid hydraulic energy into electricity, demonstrating a new pathway for harvesting energy for self-powered wireless nanodevices and nanosystems. Based on the nanogenerator mechanism, we also describe piezoelectric field-effect transistors, diodes, force/pressure sensors, and resonators. These devices form the fundamental components of nanopiezotronics, a new field in nanotechnology.