CAREER: Electrokinetic Transport of Fluid, Particles and Macromolecules through Nanochannels and Nanopores

1150590 PI：Saintilland微细加工技术的最新进展促进了微流体领域的发展。随着这些技术变得更加复杂，设备现在正在缩小到纳米级，带来了新的丰富的物理现象，可以在芯片上的实验室设备中加以利用。电动力学在这些设备中的使用已被证明在广泛的应用中特别有用，特别是在操纵流体、颗粒和大分子方面。然而，由于经典模型无法捕捉某些非连续效应，以及直接分子模拟的高成本，在纳米尺度上对这些流动的模拟仍然受到限制，因为直接分子模拟只能分辨非常短的时间尺度。这些观察结果强调了在高度受限的环境中电动力学领域需要重新建模的必要性。在这个项目中，我们建议使用一种新的模拟扩散电荷动力学的方法来研究受限器件中的电化学和大分子输运，该方法基于朗之万模型和电解质物种的布朗动力学。这种新方法将结合经典连续体模型的特征，但也将允许在不需要原子方法高昂成本的情况下捕捉非连续体效应。它既可用于研究电渗作用，也可用于研究任意尺寸的双电层电泳法，并且可以很容易地解释复杂的几何结构。基于细长体理论的波动弹性丝聚合物模型也将被用来研究任意德拜长度的聚电解质的动力学。这些新的模型和工具将被用于研究一些技术应用，包括：(I)在纳米通道中的寡核苷酸的电泳分离，(Ii)通过纳米毛细管阵列膜的电化学传输，以及(Iii)通过纳米孔的电驱动生物聚合物的传输。拟议的研究活动将有助于加强对高度受限几何结构中电动流动和大分子传输的基本理解和建模，在高度受限的几何空间中，非连续效应可能变得重要。作为研究的一部分，新的模型和模拟工具将适用于物理、工程和医学领域的广泛问题，其中包括：芯片实验室设备上的生化分析、用于基因组分析的DNA电流体拉伸、PEM燃料电池中聚合物电解质膜的电化学传输等。教育和外展活动也将纳入这一计划。伊利诺伊大学将开设一门新的研究生级别的课程，内容是微纳流体的基础和应用，包括电动流动。将设计一个关于电动力学及其应用的教程网站，供学生和非专业人员使用，并将开发扩散电荷动力学和电化学传输的可视化软件，并在公共许可证下向该领域的学生和研究人员在线提供。

1150590 PI: SaintillanRecent advances in microfabrication techniques have enabled the development of the field of microfluidics. As these techniques become more sophisticated, devices are now being scaled down to the nanoscale, bringing about a new wealth of physical phenomena to be exploited in lab-on-chip devices for instance. The use of electrokinetics in these devices has proven particularly useful in a wide range of applications, and specifically to manipulate fluid, particles and macromolecules. Yet, the modeling of these flows at the nanoscale still suffers from limitations, owing to the inability of classical models to capture certain non-continuum effects, and to the high-cost of direct molecular simulations, which are only able to resolve very short time scales. These observations emphasize the need for renewed modeling efforts in the field of electrokinetics in highly confined environments. In this project, we propose to study electrochemical and macromolecular transport in confined devices using a new simulation approach for diffuse charge dynamics based on a Langevin model and Brownian dynamics for the electrolyte species. This new method will incorporate features from classical continuum models, but will also allow one to capture non-continuum effects without the high cost of atomistic methods. It can be applied to study both electroosmosis and electrophoresis with electrical double layers of arbitrary sizes, and can easily account for complex geometries. A new polymer model based on slender-body theory for a fluctuating elastic filament will also be developed to study the dynamics of polyelectrolytes with arbitrary Debye lengths. These new models and tools will be applied to study a number of technological applications, including: (i) the electrophoretic separation of oligonucleotides in nanochannels, (ii) electrochemical transport through nanocapillary array membranes, and (iii) the electrically driven translocation of biological polymers through nanopores.The proposed research activities will serve to enhance the fundamental understanding and modeling of electrokinetic flows and macromolecular transport in highly confined geometries, where non-continuum effects may become important. The new models and simulation tools implemented as part of the research will be applicable to a wide range of problems in the fields of physics, engineering, and medicine, among which: biochemical assays on lab-on-chip devices, electrohydrodynamic stretching of DNA for genomic analysis, electrochemical transport through polymer electrolyte membranes in PEM fuel cells, and many others. Educational and outreach activities will also be integrated in this program. A new graduate-level course on fundamentals and applications of micro- and nanofluidics, including electrokinetic flows, will be introduced at the University of Illinois. A tutorial website on electrokinetics and its applications will be designed for use by students and non-specialists, and a visualization software for diffuse charge dynamics and electrochemical transport will be developed and made available online to students and researchers in the field under a public license.