Piezoelectric nanowires have been recently demonstrated for converting mechanical energy (e.g., ambient vibration or body movement) into electricity. However, the fundamentals involved in the energy harvesting process are not yet clearly understood due to the lack of well-characterized electromechanical properties of these nanowires. The objective of this research is to investigate the coupling between mechanical and electrical properties of ZnO nanowires. A microelectromechanical platform will be developed to test the mechanical and piezoelectric properties of ZnO nanowires at both quasi-static and dynamic conditions. The experiments will be carried out in-situ in scanning electron microscopy to quantitatively measure their mechanical properties and probe their fracture mechanisms. The piezoelectric constants will be measured simultaneously. Fundamental issues of piezoelectric nanowires, such as size effects and strain-gradient effects (uniaxial loading versus bending) on electromechanical coupling, will be addressed.
If successful, the proposed research will: (1) Provide a wealth of experimental data on the mechanical and piezoelectric properties of ZnO nanowires at various time scales and loading conditions of relevance to the vibration energy harvesting. (2) Enable further understanding of the energy harvesting process at the nanoscale and offer better design guidelines for nanoscale energy harvesters. (3) Develop universal nano instrumentation for systematic characterization of electromechanical-coupled properties of other 1D nanostructures. (4) Train future nano researchers in nanoscale property characterization and nanodevice design by the integration of the proposed research into the curriculum. (5) Lead to the involvement of underrepresented minorities in the nanoengineering research and education through local education and outreach activities.
