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

该学院早期职业发展(Career)项目的研究目标是开发一种新的系统识别和控制方法，以实现快速宽带粘弹性测量。通过在多个尺度上绘制软材料响应图，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，在纳米尺度、细观尺度和宏观尺度上测量材料性质存在许多障碍。它们包括(I)准静态或正弦振荡激励方法，这些方法太简单或太慢，无法快速激发软材料表现出的复杂行为；(Ii)硬件动态悄悄进入被测材料的特性，特别是在测量频率较高时；以及(Iii)显著的非线性(如磁滞)和系统不确定性。所提出的研究将通过将用于时变粘弹性模型辨识的最优输入设计与用于快速跟踪-转换切换和大系统不确定性的系统逆理论相结合来克服这些障碍。还将开发新的迭代控制和最优控制技术，以最小限度地牺牲系统带宽，实现实现最佳励磁输入所需的高速输出跟踪。这项拟议研究的结果预计将是在至少10倍的频率范围内测量软材料的时变粘弹性参数，并在至少10倍的时间范围内测量软材料的粘弹性参数。这项工作将引入一种多尺度软材料科学和工程的新范式，并通过将宏观/中观尺度的测量与纳米尺度联系起来，帮助解开伤口愈合等依赖速率的现象。所提出的方法学在纳米尺度上的实现将提高SPM作为纳米科学和纳米技术的关键使能工具的地位，促进我们对牙本质胶原脱水等快速纳米尺度现象的理解，并加速包括生物相容聚合物在内的纳米/生物材料的合成和设计。皮？S与一家领先的扫描电子显微镜制造商的密切合作将加快技术转移。拟议的职业教育活动将通过改进课程(包括一门新课程、一个教学单元和一个基于网络的扫描电子显微镜模拟器)促进机械工程领域的纳米技术教育、利用执行支助股两个成熟的外联方案、为本科生和高中科学教师提供实习机会以及为研究生提供工业实习机会，为总共450名高中女孩进行开放实验室参观。

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.