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

原子力显微镜（AFM）是一种允许在原子尺度上对物质进行询问和操纵的仪器，并彻底改变了科学和工程。基于AFM的纳米询问包括，其中一个感兴趣的是重建样品的图像的地形成像，以及其中一个希望确定固有材料特性的材料表征。AFM的主要缺点是它们的低速度，特别是当询问软物质时，例如，聚合物和生物样品。这项研究涉及先进的信号处理算法的研究，将允许同时地形成像和材料表征在超高速和高保真度。这将大大加快材料科学等领域的知识发现过程，这些领域的重点通常是快速评估新材料。研究人员将通过组织联合研讨会促进信号处理和AFM社区之间的思想交流。这些发现将通过实验室组件和模块整合到课程中。AFM使用一个带有锋利尖端的悬臂，该尖端基于原子间力偏转;通过感测和解释该偏转信号来进行询问。 这项研究的重点是动态模式操作（询问软材料的首选模式），其中悬臂梁通常是正弦激励，轻轻地轻拍介质。 目前的方法通过分析稳态悬臂轨迹来工作，并且在速度上基本上受到悬臂动力学的时间常数的限制。本研究将研究通过利用（a）系统观点和（B）更新的AFM技术（如多频激励）来提高速度的数量级。将研究用于同时检测地形特征和/或材料性质变化的信号处理算法，并在实验数据上进行详尽测试。

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.