CAREER: Joint Topographic Imaging and Materials Characterization using Atomic Force Microscopy - a Systems Approach

原子力显微镜（AFM）是一种可以在原子尺度上对物质进行询问和操纵的仪器，它给科学和工程带来了革命性的变化。基于原子力显微镜（AFM）的纳米问询包括：对重建样品图像感兴趣的地形成像，以及希望确定材料固有特性的材料表征。原子力显微镜的主要缺点是速度慢，特别是在检测软物质，如聚合物和生物样品时。这项研究包括对先进信号处理算法的研究，该算法将允许以超高速和高保真度同时进行地形成像和材料表征。这将显著加快材料科学等领域的知识发现过程，这些领域的重点往往是对新材料的快速评估。研究者将通过组织联合研讨会来促进信号处理和AFM社区之间的思想交流。研究结果将通过实验组成部分和模块整合到课程中。原子力显微镜使用一个尖端锋利的悬臂，根据原子间的力进行偏转；审讯是通过感知和解释这种偏转信号来完成的。本研究侧重于动态模式操作（询问软材料的首选模式），其中悬臂梁通常以正弦方式激发并轻轻地敲击介质。目前的方法是通过分析稳态悬臂轨迹来工作的，并且基本上受限于悬臂动力学的时间常数。这项研究将通过利用(a)系统观点和(b)新的AFM技术（如多频率激励）来研究速度的数量级改进。同时检测地形特征和/或材料属性变化的信号处理算法将被研究并在实验数据上进行详尽的测试。

The atomic force microscope (AFM) is an instrument that allows the interrogation and manipulation of matter at the atomic scale and has revolutionized science and engineering. AFM based nano-interrogation includes, topographic imaging where one is interested in recreating an image of a sample, and material characterization where one wishes to determine intrinsic material properties. The primary drawback of AFMs is their low speed especially when interrogating soft matter, e.g., polymers and biological samples. This research involves the study of advanced signal processing algorithms that will allow simultaneous topographic imaging and materials characterization at ultra-high speeds and high fidelity. This will significantly accelerate the knowledge discovery process in domains such as material science, where the focus is often on fast evaluation of new materials. The investigator will promote cross-fertilization of ideas between the signal processing and the AFM communities by organizing joint workshops. The findings will be integrated into the curriculum via lab components and modules.The AFM uses a cantilever with a sharp tip that deflects based on inter-atomic forces; interrogation is performed by sensing and interpreting this deflection signal. This research focuses on the dynamic mode operation (the preferred mode for interrogating soft material), where the cantilever is typically excited sinusoidally and gently taps the medium. Current methods work by analyzing the steady state cantilever trajectory and are fundamentally limited in speed by the time-constants of the cantilever dynamics. This research will study order-of-magnitude improvements in speed by leveraging (a) the systems viewpoint and (b) newer AFM techniques such as multi-frequency excitation. Signal processing algorithms for simultaneously detecting topographic features and/or material property changes will be studied and exhaustively tested on experimental data.