Mechanical and Piezoelectric Characterization of ZnO Nanowires for Energy Harvesting Applications

压电纳米线最近被证明可以将机械能（例如，环境振动或身体运动）转化为电能。然而，由于这些纳米线缺乏良好的机电特性，目前还不清楚能量收集过程的基本原理。本研究的目的是研究ZnO纳米线的力学和电学性能之间的耦合。本文将开发一个微机电平台来测试ZnO纳米线在准静态和动态条件下的机械和压电性能。实验将在原位扫描电镜下进行，以定量测量其力学性能并探讨其断裂机制。同时测量压电常数。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，将被解决。如果成功，本研究将：(1)提供丰富的与振动能量收集相关的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的实验数据。(2)进一步了解纳米级能量收集过程，为纳米级能量收集器的设计提供更好的指导。(3)开发通用纳米仪器，系统表征其他一维纳米结构的机电耦合特性。(4)通过将拟议的研究整合到课程中，培养未来纳米研究人员在纳米尺度特性表征和纳米器件设计方面的能力。(5)通过地方教育和推广活动，引导未被充分代表的少数民族参与纳米工程的研究和教育。

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.