NER: Developing a Nanoscale Strain Gauge

本计画的目的是发展一奈米级的应变量测器，以量测流体在界面所产生的应力。这种分子探针将从一个灵活的大分子，如单链DNA与荧光团结合到每个末端。一端将被束缚到相界面，另一端将自由延伸到变形相中。 在存在流体流动的情况下，分子将基于局部流体动力改变构型。这种变化将通过荧光共振能量转移（FRET）来测量，FRET为测量两个荧光团之间的距离提供了纳米级的“标尺”。 FRET提供了一种灵敏的手段来测量荧光团之间的距离是1-9 nm.This技术最初将开发映射流场直接相邻的界面作为一种手段来研究流动和/或变形对界面特性的影响。然而，该技术也将是有用的，在研究自组装单分子膜和栓系大分子的流动的影响。它还将通过提供对宏观力的分子尺度响应的精确测量来帮助验证多尺度建模技术。本科生和研究生将直接参与该技术的开发，并将接受荧光显微镜材料科学应用和生物共轭技术的培训。 本研究的结果还将通过提供流动/边界相互作用的可视化示例来增强学生在流体力学等课程中的课堂体验。

The objective of this project is to develop a nanoscale "strain-gauge" to measure flow-induced stresses at an interface. This molecular probe will be developed from a flexible macromolecule such as a single-strand DNA with fluorophores conjugated to each end. One end will be tethered to the phase interface and the other will extend freely into the deforming phase. In the presence of fluid flow, the molecule will change configuration, based on the local hydrodynamic forces. This change will be measured by fluorescent resonance energy transfer (FRET), which provides a nanoscale "ruler'" for measuring the distance between two fluorophores. FRET provides a sensitive means to measure distances between fluorophores that are 1-9 nm apart.This technique will initially be developed to map the flow field immediately adjacent to an interface as a means to study the effect of flow and/or deformation on interfacial properties. However, the technique will also be useful in studying the effects of flow in self-assembled monolayers and tethered macromolecules. It will also help verify multiscale modeling techniques by providing accurate measurements of molecular-scale response to macroscopic forces. Both undergraduate and graduate students will be directly involved in the development of the technique and will be trained in material science applications of fluorescent microscopy and in bioconjugate techniques. Results from the this study will also enhance the classroom experience for students in courses such as fluid mechanics by providing a visual example of flow/boundary interaction.