Collaborative Research: Active and Nonlinear Microrheology

建议没有。当前位置主要研究者：首先，Eric M./Squires, Todd M.机构：特拉华大学/加州大学圣巴巴拉分校合作研究：主动和非线性微流变学在过去的十年中，我们看到了被动微流变学技术的发展，在被动微流变学中，胶体示踪颗粒的布朗运动与周围材料的线性粘弹性有关。微流变测量的显着好处包括：仅需微升样品，提供扩展的频率范围，并具有探测空间流变变化的能力。由于这个原因，工业界对适应和采用微流变方法表现出了极大的兴趣。长期以来，人们一直认识到，处理复杂流体的大多数工业流程都与线性流变学有很大的不同。然而，被动微流变学本质上是无法测量非线性流变特性的。在这里，目标是开发第一个微流变技术来测量非线性材料特性。合作努力将开发实验技术（使用激光镊子和高速共聚焦显微镜来测量胶体探针穿过材料时的力和非平衡结构）以及理解和解释结果的理论基础。目前，所有的理论和实验都集中在直接的探针浴相互作用上，这在宏观流变学中不起作用，在被动微流变学中表现为伪影。为了建立非线性微流变学作为材料表征的一般技术，必须理解和解决这些问题，并且必须开发和验证用于解释结果的良好基础方法。在为这些问题建立了理论和实验框架之后，主要研究人员期望使用更复杂的技术（例如，涉及多个和各向异性探针）来更可靠地测量非线性体流变以及正常应力测量。智力上的优点是提出了发展和完善非线性微流变学的第一个技术，从而建立了一个全新的流变学领域。更广泛的影响是微流变学的发展有望在扩大生产到工业规模之前测量非线性特性。与宝洁公司的互动将通过合作和博士行业实习加速这些方法的转移。此外，pi将利用现有的nsf资助的扩展项目，将本科生、少数族裔、高中生和教师纳入他们的研究工作，在这个经济和技术上都很重要的领域提供教育机会。

PROPOSAL NO.: 0730292/0730270PRINCIPAL INVESTIGATOR: Furst, Eric M./Squires, Todd M. INSTITUTION: University of Delaware/University of California-Santa Barbara COLLABORATIVE RESEARCH: ACTIVE AND NONLINEAR MICRORHEOLOGY The past decade has seen the development of techniques in passive microrheology, where the Brownian motion of colloidal tracer particles is related to the linear viscoelastic properties of the surrounding material. Significantly benefits from microrheological measurements include: requiring mere microliters of sample, providing an extended range of frequencies, and having the ability to probe spatial rheological variation. For this reason, industry has shown significant interest in adapting and adopting microrheological approaches. It has long been appreciated that most industrial flows for processing complex fluids involve significant departures from linear rheology. However, passive microrheology is by nature incapable of measuring nonlinear rheological properties. Here, the goal is to develop the first microrheological techniques to measure nonlinear material properties. The collaborative effort will develop both experimental techniques (the use of laser tweezers and high speed confocal microscopy to measure the force and non-equilibrium structure as a colloidal probe is driven through a material) as well as the theoretical basis to understand and interpret the results. Currently, all theory and experiments have focused exclusively on direct probe-bath interactions, which play no role in macro-rheology and appear as artifacts in passive microrheology. To establish nonlinear microrheology as a general technique for material characterization, these issues must be understood and addressed, and well-founded methods for interpreting the results must be developed and validated. Having established the theoretical and experimental framework for these issues, the Principle Investigators anticipate using more sophisticated techniques (e.g. involving multiple and anisotropic probes) for more faithful measurements of nonlinear bulk rheology as well as normal stress measurements. The intellectual merit is in proposing to develop and refine the first techniques for nonlinear microrheology, thus establishing an entirely new area of rheology. Broader impact is the development of microrheology promises to measure nonlinear properties before scaling up production to industrial scale. Interactions with Procter and Gamble will speed transfer of these methods, both through collaboration and PhD industrial internships. Additionally, the PIs will leverage existing NSF-funded outreach programs to incorporate undergraduates, under-represented minorities and high-school students and teachers into their research efforts, providing educational opportunities in this economically and technically important field.