CAREER: Control Tools for Nanoscale Rapid Broadband Viscoelasticity Measurement and Mapping of Soft Materials

这个教师早期职业发展（Career）项目的研究目标是开发一种新的系统识别和控制方法，以实现快速的宽带粘弹性测量。通过映射软材料在多个尺度上的响应，所提出的方法将在使用扫描探针显微镜（SPM）的纳米尺度测量中实现。目前，在纳米、中观和宏观尺度上测量材料性能存在许多障碍。它们包括(i)准静态或正弦波振荡激励方法，这些方法要么太简单，要么太慢，无法快速激发软材料所表现出的复杂行为；（ii）硬件动力学渗透到被测材料特性中，特别是当测量处于高频率时；（iii）显著的非线性（如滞后）和系统不确定性。本文提出的研究将通过将时变血管弹性模型识别的最优输入设计与快速跟踪转换切换和大系统不确定性的系统反演理论相结合来克服这些障碍。新的迭代控制和最优控制技术也将被开发，以允许在最小的系统带宽权衡下施加最佳激励输入所需的高速输出跟踪。所提出的研究结果预计将在至少10倍的频率范围内和至少10倍的时间框架内测量软质材料的时变粘弹性参数。这项工作将引入多尺度软材料科学和工程的新范式，并通过将宏观/中观尺度测量与纳米尺度联系起来，帮助解开伤口愈合等速率依赖现象。在纳米尺度上实现所提出的方法将使SPM成为纳米科学和纳米技术的关键支持工具，促进我们对牙本质胶原脱水等快速纳米尺度现象的理解，并加速纳米/生物材料的合成和设计，包括用于药物输送的生物相容性聚合物。π吗?与一家领先的SPM制造商的密切合作将加速技术转移。拟议的职业教育活动将通过课程改进（包括一门新课程、一个教学模块和一个基于网络的SPM模拟器）促进机械工程领域的纳米技术教育，通过利用ISU的两个成熟的外展项目，为总共450名高中女生开放实验室参观，为本科生和高中科学教师提供实习机会，为研究生提供工业实习机会。

The research objective of this Faculty Early Career Development (CAREER) project is to develop a new system identification and control methodology to enable rapid broadband viscoelastic measurements. By mapping soft material responses at multiple scales, the proposed methodology will be realized in nanoscale measurements using scanning probe microscopy (SPM). Currently there are many barriers to measurements of material properties at the nano-, meso-, and macro-scales. They include (i) quasi-static or sinusoidal-oscillatory excitation methods which are either too simple or too slow to rapidly excite the complex behaviors exhibited by soft materials, (ii) hardware dynamics creeping into the measured material properties, particularly when the measurement is at a high frequency, and (iii) significant nonlinearity (such as hysteresis) and system uncertainties. The proposed research will overcome these barriers through the integration of optimal input design for time-varying vescoelastic model identification with the system-inversion theory for rapid tracking-transition switching and large system uncertainties. New iterative control and optimal control techniques will also be developed to allow the high-speed output tracking needed for exerting the optimal excitation input with minimal trade-off of system bandwidth. The outcome of the proposed research is expected to be the measurement of time-varying viscoelastic parameters of soft materials over a frequency range at least 10 fold larger and within a time frame at least 10 fold shorter. The work will introduce a new paradigm of multi-scale soft material sciences and engineering, and help unravel rate-dependent phenomena like wound healing by linking the macro-/meso- scale measurements to the nano- scale. The realization of the proposed methodology at the nanoscale will improve SPM as the key enabling tool for nanosciences and nanotechnologies, advance our understanding of rapid nanoscale phenomena like dentin collagen dehydration, and accelerate the synthesis and design of nano-/bio- materials including bio-compatible polymers for drug delivery. The PI?s close collaboration with a leading SPM manufacturer will accelerate the technology transfer. The proposed CAREER education activities will promote nanotechnology education in mechanical engineering, through curriculum improvements (including a new course, a teaching module and a web-based SPM simulator), open lab tours for a total of 450 high-school girls by leveraging two well-established outreach programs at ISU, internships for undergraduate women students and high-school science teachers, and industrial internships for graduate students.