Electrowetting Effects and Nanoscale Transport

在化学系化学测量和成像项目的支持下，圣母大学的Paul Bohn教授和他的团队正在研究受自然启发的新型人造材料的设计，行为和可能的应用，特别是由分层膜组成的架构，其中每层都有不同的孔结构。这项工作的动机是从分子分离到催化的应用。例如，这些材料可以在诸如饮料澄清、从血液中清除病原体以及药物的受控释放和用于疾病特异性生物标志物的高选择性传感器等应用中选择性地去除不需要的组分。这些实验将建立控制液体在壁上润湿特性的专门知识，从而使在技术应用中使用先进的流体控制概念成为可能，例如复杂流体中的分离。这项工作还与新的跨学科跨大学计划的开发相结合，并解决特定的NSF目标，包括开发多样化，具有全球竞争力的STEM（科学，技术，工程和数学）劳动力，学术界和工业界之间的伙伴关系增加，经济竞争力提高。该项目解决纳米级密闭体积中的运输，其突出了一组核心科学现象-润湿/去润湿、疏水性、流体流动中的随机波动、电动力学等-这些现象在纳米尺度上表现出根本不同的行为。该研究围绕两个总体目标进行组织：开发基于单分子的电动和光谱电化学探针在一维（1D）纳米结构中的运输;并应用这些工具来探索电调制润湿现象和纳米限制流之间的相互作用。第一个目标将通过制造结构来实现超低Peclét数制度中的运输;开发相关和频域测量来表征流体运输和流体-壁相互作用;并实施这些测量策略来研究受限的1D纳米柱和纳米通道流动格式中的电动流动。第二个目标将通过开发支持电润湿现象的纳米限制架构来实现;并应用电润湿原理来控制两个模型系统和分层组织的多层结构中的纳米限制流，该多层结构具有深度变化的孔隙率。这些实验将建立控制溶剂-壁系统的润湿特性所必需的条件。 研究将在一个明确的水-有机溶剂界面中进行，该界面可以支持定量电化学和光谱实验，这些实验能够报告水-有机界面的状态作为施加电势的函数。这些研究旨在建立设计规则、结构图案和操作原则，以实现对纳米受限体积中分子传输的高水平控制。该奖项反映了NSF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。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Paul Bohn and his group at the University of Notre Dame are studying the design, behavior, and possible applications of new artificial materials inspired by Nature, particularly architectures consisting of layered films where each layer has a different pore structure. The work is motivated by applications ranging from molecular separations to catalysis. For example, these materials can selectively remove unwanted components in applications such as beverage clarification, clearance of pathogens from blood, and in controlled release of drugs and highly selective sensors for disease-specific biomarkers. These experiments will establish the know-how to control the wetting characteristics of the liquid on the wall, thereby making it possible to use advanced fluid control concepts in technological applications, such as separations in complex fluids. The work is also coupled with the development of new multi-university programs that cut across disciplinary lines and address specific NSF goals, including the development of a diverse, globally competitive STEM (science, technology, engineering and mathematics) workforce, increased partnerships between academia and industry, and increased economic competitiveness.The project addresses transport in nanoscale confined volumes, which highlights a core set of scientific phenomena - wetting/dewetting, hydrophobicity, stochastic fluctuations in fluid flow, electrokinetics, etc. - that exhibit fundamentally distinct behavior on the nanoscale. The research is organized around two overarching objectives: developing single molecule-based electrokinetic and spectro-electrochemical probes of transport in one-dimensional (1D) nanostructures; and applying these tools to explore the interaction between electrically-modulated wetting phenomena and nanoconfined flows. The first objective will be addressed by fabricating structures to access transport in the ultralow Peclét number regime; developing correlative and frequency-domain measurements to characterize fluid transport and fluid-wall interactions; and implementing these measurement strategies to study electrokinetic flows in confined 1D nanocylinder and nanochannel flow formats. The second objective will be pursued by developing nanoconfined architectures that support electrowetting phenomena; and applying electrowetting principles to control nanoconfined flow in both model systems and in hierarchically-organized, multi-lamellar structures with depth-varying porosity. These experiments will establish the conditions necessary to control the wetting characteristics of the solvent-wall system. Studies will be implemented in a well-defined water-organic solvent interface that can support quantitative electrochemical and spectroscopic experiments capable of reporting on the state of the aqueous-organic interfaces as a function of applied potential. These studies are directed at establishing the design rules, structural motifs, and operating principles needed to achieve a high level of control over molecular transport in nano-confined volumes.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.