Nonlinear Electrophoresis of Charged Colloidal Particles

带电胶体粒子的非线性电泳

基本信息

批准号：
2002120
负责人：
Aditya Khair
金额：
$ 29.93万
依托单位：
Carnegie-Mellon University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-01 至 2023-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2002120&HistoricalAwards=false
关键词：
Nonlinear Electrophoresis Charged Colloidal Particles

项目摘要

The goal of this project is to predict and measure how electrically charged particles in electrolyte solutions move under strong voltages. Such motion is called electrophoresis and is important in lab-on-a-chip devices, e-ink displays, pigments, coatings, and the petroleum industry. A central objective is to quantify the ratio of the speed of the particle to the voltage strength, which is known as the electrophoretic mobility. Such measurements are conducted to infer the electrical charge of a particle, a key quantity in predicting the behavior of suspensions of particles. One complication is that electrophoretic mobility may depend on the voltage in non-linear way, particularly with large voltages in organic electrolytes (e.g. oils doped with surfactant molecules). However, predictive models for this nonlinear, voltage-dependent mobility are lacking. Thus, the intellectual merit of this project is to develop theory and numerical computations to predict the nonlinear mobility, which will be compared to experimental measurements. A broader technological impact is the development of new methods to determine particle charge to aid in designing dispersions with enhanced stability, which will benefit the formulation of household and personal-care products that use organic solvents. The educational broader impact of this project includes course development, undergraduate research, and outreach activities. For the latter, educational modules for K-12 students will be developed and integrated into existing outreach programs at Carnegie Mellon University.The intellectual merit of this project is to predict the electric field-dependent mobility of a charged colloidal particle via numerical solution of the electrokinetic equations governing fluid flow, ion transport and reaction kinetics, and electrostatic fields in electrophoresis. These predictions will be compared against experimental measurements, which will enable feedback to refine modeling assumptions. The numerical scheme will employ a custom spectral element code that is ideally suited to the task. The project is split into two technical objectives. Objective 1 is focused on steady electrophoresis under a uniform, steady (dc) field, for which the mobility is time independent. The goal is to compute the field-dependent mobility over the entire range of experimentally relevant field strength. In objective 2, particle motion under a single frequency ac field will be examined, for which the mobility is time dependent. Here, the hypothesis is that the nonlinear distortion of the Debye cloud, beyond the weak-field limit, leads to rectified migration under an ac field, due to a mismatch in the diffusion coefficients of the cations and anions in an electrolyte. The project is novel since previous efforts have predominantly focused on weak applied fields, where the mobility is field-independent. The project will generate new computational tools to analyze experiments on nonlinear electrophoresis. This will have a broader impact to the colloid science and soft matter communities, who will be able to use the results to infer surface charge from field-dependent mobility measurements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目的目的是预测和测量电解质溶液中电荷颗粒在强电压下的移动。这种运动称为电泳，在芯片上的实验室设备，电子墨水显示器，颜料，涂料和石油行业中很重要。一个中心目标是量化粒子速度与电压强度的比率，这称为电泳迁移率。进行此类测量是为了推断粒子的电荷，这是预测颗粒悬浮液行为的关键量。一种并发症是电泳迁移率可能取决于非线性方式的电压，尤其是有机电解质中的大电压（例如，掺杂表面活性剂分子的油）。但是，缺乏这种非线性，电压依赖性迁移率的预测模型。因此，该项目的智力优点是开发理论和数值计算以预测非线性迁移率，这将与实验测量进行比较。更广泛的技术影响是开发新方法，以确定粒子费用以帮助设计具有增强稳定性的分散体，这将有利于使用有机溶剂的家庭和个人护理产品的制定。该项目的教育更广泛的影响包括课程发展，本科研究和外展活动。对于后者，将开发K-12学生的教育模块，并将其整合到卡内基梅隆大学的现有外展计划中。该项目的智力优点是通过通过数值解决方案的数值解决方案来预测带电胶体粒子的电气依赖性移动性。电泳中的流体流，离子传输和反应动力学以及电泳中的静电场的电动方程。这些预测将与实验测量值进行比较，这将使反馈以完善建模假设。数值方案将采用理想适合任务的自定义频谱元素代码。该项目分为两个技术目标。物镜1集中在均匀，稳定（DC）场下的稳定电泳上，而迁移率无关。目的是计算整个实验相关的田间强度范围内依赖场的迁移率。在目标2中，将检查单个频率AC场下的粒子运动，其中迁移率取决于时间。在这里，假设是，由于阳离子和电解质中阳离子的扩散系数和阴离子的扩散系数不匹配，debye云的非线性失真（超过弱场极限）导致了逆向迁移。该项目是新颖的，因为以前的努力主要集中在弱应用领域，在该领域中，该领域是独立于场的。该项目将生成新的计算工具来分析非线性电泳实验。这将对胶体科学和软物质社区产生更大的影响，他们将能够利用结果从依赖现场的移动性测量中推断出表面指控。该奖项反映了NSF的法定任务，并被认为是值得通过使用的支持。基金会的智力优点和更广泛的影响审查标准。