CAREER: Alternating Current Electrophoresis in Spatially Non-Uniform Electric Fields

电解质是导电的带电离子和分子，如钠、锂和氢氧化钾。对溶液中的电解液施加交流电(AC)电场会使它们因其电荷性质而迁移。这一现象被用于许多重要的应用，包括超级电容器、高倍率电池，以及细胞和生物分子操作，如细胞分选。交流电场可以是交流电压的规则波(空间均匀)，也可以是不可预测的不规则波(空间非均匀)。科学家假设，对电解液施加交流电压会鼓励电解液以一种不影响整体溶液性质的方式迁移。然而，最近的研究表明，当施加空间不均匀的交流电场时，电解质溶液的性质会发生变化。观察到了流动反转、pH漂移、溶液渗透压变化以及离子浓度梯度的产生等影响。该项目的目标是了解电解质和其他带电粒子在较长时间内如何响应主体溶液中空间不均匀的交流电场。这些基础知识可用于开发分子生物传感、海水淡化和高通量药物筛选分析的新技术。该项目还将支持STEM外联和教育活动。它旨在通过与行业领袖的互动和了解行业情况的学生项目，为研究生和本科生开发与行业相关的技能。研究人员还旨在培养人们对STEM教育和技术驱动的解决方案的兴趣，以提高来自服务不足社区的高中生的医疗保健和社会福祉。该项目将测试以下假设：空间非均匀交流电场下的偏置交流电迁移有助于在大块水相和生物流体中定向浓缩和产生与生物化学相关的带电物种的浓度梯度。具体的研究目标是：(A)设计一个从偏置交流电迁移中分离混杂变量的新系统，(B)考察空间非均匀交流电场性质对指定带电物种偏置交流电迁移行为的影响，以及(C)阐明带电物种的固有属性对其在指定空间非均匀交流电场下偏置交流电迁移行为的影响。这个项目将提供一个基本的理解，带电物种在空间不均匀的交流电场下的行为，在主体溶液中，超过双电层和更长的时间比以前研究(60秒)。这种对偏置交流电迁移的基本理解与许多科学界广泛相关；它可以用于开发以下技术：(1)选择性地富含或消耗生物分子，通过允许检测到低于检测限值的目标分子的浓度来提高生物传感的灵敏度和准确性，以及(2)产生在空间和时间上可控的和可量化的二维和三维梯度。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Electrolytes are charged ions and molecules such as sodium, lithium, and potassium hydroxide that conduct electricity. Applying an alternating current (AC) electric field to electrolytes in a solution causes them to migrate because of their charge properties. This phenomenon is used in many important applications, including supercapacitors, high-rate batteries, and cellular and biomolecular manipulation like cell sorting. AC electric fields can be regular waves of alternating voltage (spatially uniform) or less predictable, irregular waves (spatially non-uniform). Scientists have assumed that applying AC voltages to an electrolyte solution encourages the electrolytes to migrate in a way that does not affect the overall bulk solution properties. However, recent research studies revealed that electrolyte bulk solution properties change when a spatially non-uniform AC electric field is applied. Effects such as flow reversal, pH shifts, solution osmotic pressure change, and the generation of ion concentration gradients were observed. This project’s objective is to understand how electrolytes and other charged particles respond to spatially non-uniform AC electric fields in bulk solutions over extended periods. This fundamental knowledge can be applied to develop novel technologies for molecular biosensing, water desalination, and high-throughput drug screening assays. The project will also support STEM outreach and educational activities. It aims to develop industrially relevant skillsets for graduate and undergraduate students through interactions with industrial leaders and industry-informed student projects. The investigator also aims to cultivate interest in STEM education and technology-driven solutions to enhance healthcare and societal well-being among high school students from underserved communities.This project will test the hypothesis that the biased AC electromigration under spatially non-uniform AC electric fields facilitates the directed enrichment and generation of concentration gradients of biochemically relevant charged species in bulk aqueous phase and biofluids. The specific research objectives are to (A) engineer a new system for isolating confounding variables from biased AC electromigration, (B) interrogate the influence of spatially non-uniform AC electric field properties on biased AC electromigration behaviors of designated charged species, and (C) elucidate the influence of charged species’ intrinsic properties on their biased AC electromigration behavior under designated spatially non-uniform AC electric fields. This project will provide a fundamental understanding of the behaviors of charged species under spatially non-uniform AC electric fields in the bulk solution beyond the electric double layer and at longer times than previously studied (60 seconds). This fundamental understanding of biased AC electromigration is broadly relevant to many scientific communities; it can be applied to develop technologies that (1) selectively enrich or deplete biomolecules, which will improve the sensitivity and accuracy of biosensing by allowing the detection of concentrations of target molecules that are otherwise below detection limits and (2) generate spatially and temporally controllable and quantifiable two- and three-dimensional gradients.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.