RUI: Modeling of electrokinetic flows at large applied voltages

存储微流控器件是未来应用的关键组件，包括大规模并行药物发现、针对生物和化学威胁的集成传感器以及个性化药物。尽管许多微流控系统体积小，但由于操作电压较大，目前使用的许多微流控系统仅限于实验室。一种在通道内放置微米尺寸电极的相对较新的设备很有希望，因为它们在相对较低的电压下工作--这是便携性的关键要求。这些器件的大多数计算模型都是基于经典的电动现象理论，该理论将电解液中的流体流动、离子传输和电场耦合在一起。不幸的是，这些模型未能预测到一些至关重要的实验趋势，阻碍了它们的发展。PI和合作者最近的工作已经开始对经典的电动力学理论进行简单的修正，以解释一些主要的缺陷。到目前为止，修正后的模型可以预测一些关键趋势，但模型和实验之间的一致性仍然不足。这项工作的总体目标是提高在这些电驱动微流控应用中的建模能力，以便人们可以使用相对简单的模拟作为工程设计的工具。虽然人们真正感兴趣的现象是纳米级的，但提出的策略是开发一种准确但易于处理的基于连续统的配方，可以被其他研究人员应用。这项研究有两个主要的信任。首先是研究表面粗糙度在模型中的作用。第二个重点将是研究电极表面的电化学反应在这些流动的模型中所起的作用。我们的假设是，包含这两种效应可以在很大程度上解决模拟和实验之间的关键差异。虽然电动力学领域非常成熟，但感兴趣的微流体设计在通常使用的理论的某些方面不适用的情况下运行。这项研究开发了几个精心规划的研究项目，为Olin本科生提供身临其境的、现代的和成功的研究体验。

0930484StoreyMicrofluidic devices are critical components of promising future applications including massively parallel drug discovery, integrated sensors for biological and chemical threats, and personalized medicine. Despite their small size, many microfluidic systems currently in use are limited to the laboratory due to large operational voltages. A relatively new class of device that places micron size electrodes inside channels is promising as they operate at relatively low voltage--a key requirement for portability. Most computational models of these devices are based in the classical theory of electrokinetic phenomena which couples fluid flow, ion transport and electric fields in electrolytes. Unfortunately, these models fail to predict some critically important experimental trends, impeding their development. Recent work by the PI and collaborators has started to apply simple corrections to the classical theory of electrokinetics to account for some of the major deficiencies. To date, the corrected models can predict some of the key trends but the agreement between model and experiment is still lacking. The overall objective of this work is to improve modeling capability in these electrically driven microfluidic applications such that one can use relatively simple simulations as a tool for engineering design. While the phenomena of interest is truly at the nanoscale, the strategy put forth is to develop an accurate yet tractable continuum-based formulation that can be applied by other researchers. This study has two main trusts. The first is to study the role of incorporating surface roughness into the model. The second thrust will be to investigate the role that electrochemical reactions at the electrode surface plays in models of these flows. The hypothesis is that inclusion of these two effects can go a long way toward resolving key discrepancies between simulation and experiment. While the field of electrokinetics is very mature, the microfluidic designs of interest operate in regimes where aspects of the commonly used theory do not apply. This study develops several carefully planned research projects to provide Olin undergraduate students with an immersive, modern and successful research experience.