Nonlinear Dynamics of Microcantilevers Interacting with Nanostructures: New Paradigms for Ultrasensitive Atomic Force Microscopy

微悬臂梁与纳米结构相互作用的非线性动力学：超灵敏原子力显微镜的新范例

• 批准号: 0700289
• 负责人: Arvind Raman
• 金额: $ 25.97万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0700289&HistoricalAwards=false
• 关键词: Nonlinear; Dynamics; Microcantilevers; Interacting; Nanostructures

This project investigates the dynamics of new ultrasensitive modes for nanoscale imaging and force sensing in the Atomic Force Microscope (AFM) that could impact significantly its considerable applications in nanotechnology, material science, biology, condensed matter physics, and data storage technology. Continuous rod models of AFM microcantilevers driven at parametric and nonlinear resonances (sub-, superharmonic and combination) are systematically discretized about their equilibrium position under the action of tip-sample interaction forces. The dynamics of the discretized model are studied using (1) analytical asymptotic techniques to accommodate non-smoothness of tip-sample interaction forces, and (2) accurate numerical simulations for non-smooth systems. A focus is placed on identifying regions in parameter space with greatest sensitivity to tip-sample interaction forces as well as regions corresponding to bifurcations and unstable dynamics. Careful experiments are performed on different microcantilevers and sample materials with a custom built AFM with dual lock-in amplifiers that allow for different excitation and response frequencies, a typical situation for parametric and nonlinear resonance. The Atomic Force Microscope (AFM) has become one of the most important tools for nanotechnology with its remarkable ability to measure nanoscale forces and image and manipulate atoms and molecules with nanometer resolution. Efforts are ongoing around the world to improve the sensitivity of this key enabling tool for nanotechnology; however, under ambient conditions this sensitivity is fundamentally limited by the nature of excitation and the quality factor (Q-factor) of the resonance. Greater sensitivity to nanoscale interaction forces could enable the AFM to reveal material property contrast and detect nanoscale forces that are otherwise hidden in background noise. The proposed research aims to create entirely new AFM modes by oscillating the AFM probes using (a) parametric and (b) nonlinear resonances that could bypass the current limits on sensitivity in conventional AFM systems. In doing so, the research could open the door to scientific breakthroughs in diverse AFM applications including the imaging and spectroscopy of biological molecules, probe-based data storage, and synthesis and characterization of nanomaterials. Given the explosion of AFM's in University campuses and research labs around the world, there is a rapidly growing body of AFM experimentalists who are not trained in dynamics and little realize its importance in this "microscope". The project uses the existing framework of the NSF supported nanoHUB (www.nanohub.org) to create online simulation tools for AFM dynamics that would be accessible to hundreds of experimentalists and educators worldwide. Created by the Network for Computational Nanotechnology (NCN), this is a NSF-funded initiative connecting theory, experiment, and computation one of NSF's success stories in the use of cyberinfrastructure to spur scientific research. Not only is the use of these tools expected to aid the interpretation of AFM data and reduce AFM training time for graduate students and researchers worldwide, it also serves as an excellent resource for teaching fundamental and advanced concepts of scanning probe microscopy in both undergraduate and graduate classes.

该项目研究了原子力显微镜（AFM）中纳米级成像和力传感的新超灵敏模式的动态，这可能会显著影响其在纳米技术，材料科学，生物学，凝聚态物理学和数据存储技术中的大量应用。连续杆模型的原子力显微镜微悬臂梁驱动参数和非线性共振（次，超谐波和组合）系统离散其平衡位置的作用下的针尖样品的相互作用力。 离散化模型的动力学研究使用（1）分析渐近技术，以适应非光滑的尖端-样品相互作用力，和（2）精确的数值模拟非光滑系统。一个重点是放在识别区域的参数空间中的最大灵敏度的尖端样品的相互作用力，以及对应的分叉和不稳定的动态区域。仔细的实验进行了不同的微悬臂梁和样品材料与定制的AFM与双锁定放大器，允许不同的激励和响应频率，一个典型的情况下，参数和非线性共振。原子力显微镜（AFM）以其测量纳米级力、成像和操纵原子和分子的纳米分辨率的卓越能力，已成为纳米技术最重要的工具之一。世界各地都在努力提高这一关键的纳米技术使能工具的灵敏度;然而，在环境条件下，这种灵敏度从根本上受到激励性质和谐振品质因数（Q因数）的限制。 对纳米级相互作用力的更高灵敏度可以使AFM能够揭示材料特性对比，并检测隐藏在背景噪声中的纳米级作用力。拟议的研究旨在创建全新的AFM模式，通过振荡的AFM探针使用（a）参数和（B）非线性共振，可以绕过目前的限制，在传统的AFM系统的灵敏度。在这样做的过程中，该研究可以为各种AFM应用的科学突破打开大门，包括生物分子的成像和光谱学，基于探针的数据存储以及纳米材料的合成和表征。鉴于原子力显微镜在世界各地的大学校园和研究实验室的爆炸，有一个快速增长的原子力显微镜实验者谁没有受过动力学训练，很少意识到它在这个“显微镜”的重要性。该项目使用NSF支持的nanoHUB（www.nanohub.org）的现有框架来创建AFM动力学的在线模拟工具，全球数百名实验人员和教育工作者都可以使用。这是由计算纳米技术网络（NCN）创建的，是NSF资助的一项将理论、实验和计算联系起来的计划，是NSF在利用网络基础设施促进科学研究方面的成功案例之一。不仅是使用这些工具，预计将有助于解释AFM数据和减少AFM培训时间的研究生和研究人员在世界各地，它也作为一个很好的资源，用于教学的基本和先进的概念扫描探针显微镜在本科和研究生班。