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

电解质是带电离子和分子，如钠、锂和氢氧化钾，它们可以导电。对溶液中的电解质施加交流电场会使其由于电荷特性而发生迁移。这种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（空间不均匀）。科学家们假设，在电解质溶液中施加交流电压会促使电解质以一种不影响整体溶液性质的方式迁移。然而，近年来的研究表明，在空间非均匀的交流电场作用下，电解质体溶液的性质发生了变化。观察了回流、pH值变化、溶液渗透压变化和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长时间内对大块溶液中空间不均匀的交流电场的反应。这些基础知识可以应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外展和教育活动。它旨在通过与行业领导者和行业知情学生项目的互动，培养研究生和本科生的工业相关技能。研究人员还旨在培养对STEM教育和技术驱动解决方案的兴趣，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。该项目将验证在空间非均匀交流电场下的偏置交流电迁移有助于在散装水相和生物流体中定向富集和产生生化相关带电物质浓度梯度的假设。具体的研究目标是：(A)设计一个新的系统来隔离偏置交流电迁移的混杂变量，(B)询问空间非均匀交流电场性质对指定带电物质的偏置交流电迁移行为的影响，以及(C)阐明在指定的空间非均匀交流电场下带电物质的固有性质对其偏置交流电迁移行为的影响。该项目将对带电物质在双电层以外的体溶液中空间非均匀交流电场下的行为提供基本的理解，并且比以前研究的时间更长（60秒）。这种对偏压交流电迁移的基本理解与许多科学界广泛相关；它可以应用于开发以下技术：(1)选择性地富集或耗尽生物分子，这将通过允许检测低于检测限的目标分子的浓度来提高生物传感的灵敏度和准确性；(2)产生空间和时间可控和可量化的二维和三维梯度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.