面向AFM微悬臂刚度标定的微力测量系统及其关键技术研究

To satisfy the great requirements of rigidity calibration of Atomic Force Microscopy(AFM) cantilever, the key technologies on design of micro/nano-newton force measurement system are studied, which is based on compliant mechanisms, theories of static electricity actuators. Firstly, optimization design methodologies for mechanical structures of micro/nano-newton force measurement system will be studied, and dynamic modeling of complex mechanical-electrical coupling system will be processed, and virtual prototype technology will be adopted. Secondly, the high-robust control system will be constructed based on laser dynamic measurement technologies and theories of measurement in Null Position, and the integrated technologies will be developed to assure general characteristics including static and dynamic properties. Lastly, dynamic design theories about rigidity measurement and calibration of AFM cantilever based on micro/nano-newton force measurement system and high-precision position table, and some measures will be provided and discussed to improve calibration precision and reliability. The goals of this project are set as: the integrated innovating design theory and methodology on micro/nano-newton force measurement system, based on parallel compliant mechanisms and static electricity actuators, can be provided; some key technologies about traceable micro/nano-newton force measurement, based on laser dynamic measurement technologies and theories of measurement in Null Position, can be solved; calibration of AFM cantilever with high precision and reliability, based on micro/nano-newton force measurement system and high-precision position table, can be realized. All of these will be valuable to improve and develop foundational theories of micro/nano-newton force measurement system.

本项目拟面向AFM探针微悬臂刚度标定的重大需求，开展基于柔顺机构和静电致动原理的微/纳牛顿量级微力测量系统设计及关键技术的研究。重点研究微力测量系统的机械结构优化设计方法，建立复杂机电耦合系统动力学模型，掌握虚拟样机设计技术，搭建基于激光动态测量技术和零位测量原理的高鲁棒性控制系统，开发保障静动态综合性能指标的系统集成技术，开展基于微力测量系统与高精度定位平台的AFM探针微悬臂刚度测量系统动态设计理论研究，探讨提高标定精度和可靠性的综合保障措施。通过本项目的研究，力争形成一套基于并联柔顺机构与静电致动器的微力测量装置一体化创新设计理论方法体系，攻克基于激光干涉动态测量和零位检测方法的微力可溯源性测试关键技术，实现基于新型微力测量装置和高精度定位平台的AFM探针微悬臂刚度的精确可靠标定，丰富和发展微力测量系统的基础理论，为加强我国微/纳量级微力测量系统设计能力和赶超国际先进水平贡献力量。

AFM在表面形貌测量和纳米操纵等领域具有广泛的应用，利用AFM开展微小力测量是AFM的重要应用领域之一，而微悬臂作为AFM输出信号和探针载体，其刚度标定对AFM测量结果准确性具有重要影响。本项目面向AFM探针微悬臂刚度标定的重大需求，结合AFM力学测量中的实际问题，研究了微悬臂梁刚度标定技术，建立了电磁驱动系统和平衡测量系统，根据零位测量方法，搭建了微悬臂梁刚度标定实验平台，实现了多种微悬臂梁的刚度标定。针对微悬臂梁驱动系统，建立了电磁力理论模型，探讨了电磁驱动系统参数对电磁力性能的影响。针对不同刚度的微悬臂梁，基于零位测量方法，建立多种刚度平衡系统，即柔性悬臂梁系统和零刚度系统，零刚度区间达到 17 μm。提出了微悬臂梁刚度标定系统的设计和建模方法，完成了微悬臂梁法向刚度标定系统的开发。在微悬臂梁刚度标定系统的仿真研究中，依据刚度的不同，分别建立了单臂式柔性悬臂梁、旋转对称式柔性悬臂梁、螺旋式柔性悬臂梁以及零刚度平台的几何模型，利用有限元软件 ANSYS 分别研究了柔性悬臂梁模型的静动态特性，优化各结构的尺寸参数。通过仿真结果，验证了理论模型的准确性。基于搭建的微悬臂梁刚度标定系统，对不同刚度的微悬臂梁进行刚度标定实验，其中电磁力与输入电流之间的转换率为 40.08 μN/mA，柔性悬臂梁的刚度为 27.17 N/m。通过多次标定实验，验证了标定系统的准确性和可重复性，并分析总结了各标定系统的不确定度（约为0.78%）。实验结果表明所开发的微悬臂梁刚度标定系统能够满足微悬臂梁刚度精确标定要求。相应成果共在国内外学术刊物和国际会议上发表论文11篇，其中 SCI检索7篇，EI检索11篇，授权国家发明专利5项。培养博士研究生3名，硕士研究生2名。本项目的研究不仅有利于我国赶超国外相应研究领域的设计水平，而且提高了我国先进制造技术的综合实力。