Influence of Confinement on Flow, Diffusion, and Boundary Conditions in Nano Channels: A Combined Quantum Dot Imaging and Molecular Dynamics Simulations Approach

约束对纳米通道中流动、扩散和边界条件的影响：量子点成像和分子动力学模拟相结合的方法

• 批准号: 1033662
• 负责人: Nikolai Priezjev
• 金额: $ 36万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1033662&HistoricalAwards=false
• 关键词: Influence; Confinement; Flow; Diffusion; Boundary

As engineered systems below the micron scale become more viable for biological and chemical analysis and detection, the boundary condition at the liquid-solid interface plays an increasingly important role in fluid flow and transport of nanoparticles. Using quantum dot (QD) imaging as a tool for interrogation of flow and nanoparticle transport and diffusion within nano channels, we utilize a combined experimental and computational approach based on molecular dynamics (MD) simulations to investigate the fundamental principles of liquid flow, diffusion, and confinement in nano channels. Specifically, the aim is to interrogate the solid-liquid slip boundary condition based on the diffusive motion of QD nano-particles and at the same time answer the following questions: (1) How does confinement affect the thermal diffusive motion of a nanoparticle in equilibrium and in the presence of shear flow? (2) How do surface characteristics (nanoroughness and wetting) affect the slip flow in a confined geometry and the local mobility of a nanoparticle? Answers to these questions are important to designing chemo- and bio-sensing technologies that involve micro- and nano-fluidics.Intellectual Merit: The proposed research is focused on addressing the fundamental questions regarding the solid-liquid boundary condition by using the measurement of the thermal motion of nanoparticle in a nano channel as a sensitive method of probing the degree of fluid slip at the surface. The quantum dot imaging method proposed here introduces a powerful approach for obtaining quantitative information about flow and transport within nano channels. The integration of experiments and molecular dynamics simulations is unique, in that the simulations are used to help interpret the experimental results by identifying and isolating the various physical effects that influence the fluid flow and the dynamics of QD nanoparticles. Broader Impacts: The experimental and computational methods developed in this proposal will be beneficial to a broad range of researchers in physics and engineering who investigate and wish to control fluid transport properties at micro and nano scales. In many chemo- and bio-sensing applications in microfluidics, the detection of a chemo/bio agent is limited by its transport towards the sensor located at the channel wall. The fundamental knowledge gained from the proposed work will directly impact the design of methods to address these detection limits. An important impact of this work will be the education of two PhD students, along with the early involvement of undergraduate students in research. The technical focus of the PIs and their approaches to computational and experimental nano-scale research will educate our students by providing a broad interdisciplinary exposure to nano-scale flow physics, modern experimentation, large-scale computations, and optical diagnostics. In addition to educating graduate students as future educators and researchers, our program will include undergraduate student researchers each summer. The PIs plan to give a two-day workshop on their nano-scale research to mid-Michigan high school science teachers enrolled in MSU?s teacher certification program, to provide them with ideas for stimulating their own high-schoolers in the current thrusts of modern research and how they relate to basic science and engineering. The quantum dot imaging methods developed in this research program will add educational material to our existing graduate level course in experimental methods in fluid dynamics. A new graduate course will be designed to educate our students in computational methods based on Monte Carlo and molecular dynamics. The scientific progress of the proposed research will be disseminated through technical conferences and journal publications. In addition, we plan to develop a website for this project with simple simulations and explanation of nano-scale flows.

随着微米级以下的工程系统越来越多地用于生物和化学分析和检测，液-固界面上的边界条件在流体流动和纳米颗粒的传输中发挥着越来越重要的作用。利用量子点(QD)成像作为研究纳米通道内流动和纳米颗粒传输与扩散的工具，我们利用基于分子动力学(MD)模拟的实验和计算相结合的方法来研究纳米通道中液体流动、扩散和限制的基本原理。具体地说，其目的是基于量子点纳米颗粒的扩散运动来询问固-液滑移边界条件，并同时回答以下问题：(1)约束如何影响纳米颗粒在平衡和存在剪切流的情况下的热扩散运动？(2)表面特征(纳米粗糙度和润湿性)如何影响受限几何形状中的滑移流动和纳米颗粒的局部迁移率？这些问题的答案对于设计涉及微纳流体的化学和生物传感技术非常重要。智能优点：拟议的研究重点是通过测量纳米颗粒在纳米通道中的热运动来解决固-液边界条件的基本问题，作为探测表面流体滑移程度的灵敏方法。这里提出的量子点成像方法为获得有关纳米通道内流动和输运的定量信息提供了一种强有力的方法。实验和分子动力学模拟的结合是独一无二的，因为模拟被用来通过识别和隔离影响流体流动和量子点纳米颗粒动力学的各种物理效应来帮助解释实验结果。更广泛的影响：本提案中开发的实验和计算方法将有益于物理和工程领域的广泛研究人员，他们研究并希望在微米和纳米尺度上控制流体传输特性。在微流体中的许多化学和生物传感应用中，化学/生物制剂的检测受到其向位于通道壁上的传感器的传输的限制。从拟议的工作中获得的基本知识将直接影响解决这些检测限度的方法的设计。这项工作的一个重要影响将是两名博士生的教育，以及本科生早期参与研究。PI的技术重点及其对计算和实验纳米级研究的方法将通过提供对纳米级流动物理、现代实验、大规模计算和光学诊断的广泛跨学科接触来教育我们的学生。除了将研究生培养成未来的教育工作者和研究人员外，我们的项目还将包括每年夏天的本科生研究人员。PIS计划为参加密歇根州立大学S教师认证计划的密歇根州中部高中的科学教师举办为期两天的纳米级研究研讨会，为他们提供想法，以激励他们的高中生参与当前的现代研究，以及他们与基础科学和工程的关系。本研究项目中开发的量子点成像方法将为我们现有的流体动力学实验方法研究生课程增加教材。我们将设计一门新的研究生课程，教授我们的学生基于蒙特卡罗和分子动力学的计算方法。拟议研究的科学进展将通过技术会议和期刊出版物传播。此外，我们计划为这个项目开发一个网站，提供简单的纳米级流动模拟和解释。