Mechanical and Piezoelectric Characterization of ZnO Nanowires for Energy Harvesting Applications

压电纳米线最近已经被证明用于转换机械能（例如，环境振动或身体运动）转换成电。然而，在能量收集过程中所涉及的基本原理尚未清楚地了解，由于缺乏良好的表征这些纳米线的机电性能。本研究的目的是探讨氧化锌纳米线的机械和电气性能之间的耦合。本研究将发展一个微机电平台来测试氧化锌奈米线在准静态与动态条件下的机械与压电特性。实验将在扫描电子显微镜中原位进行，以定量测量其机械性能并探测其断裂机制。压电常数将同时测量。本论文将研究压电纳米线的基本问题，如尺寸效应和应变梯度效应（单轴加载与弯曲）对机电耦合的影响，如果获得成功，本论文将：（1）提供丰富的实验数据，研究ZnO纳米线在不同时间尺度和加载条件下的力学和压电性能，并与振动能量收集相关。(2)能够进一步了解纳米级的能量收集过程，并为纳米级能量收集器提供更好的设计指南。(3)开发通用的纳米仪器，用于其他一维纳米结构的机电耦合特性的系统表征。(4)通过将拟议的研究纳入课程，培养未来的纳米研究人员在纳米级性能表征和纳米器件设计。(5)通过地方教育和外联活动，使代表性不足的少数群体参与纳米工程研究和教育。

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.