Investigation of transient transport processes using single gold nanopores as modelsystems

在该项目中，将制造具有定制几何形状、直径、长度和表面电荷的单聚合物轨迹蚀刻纳米通道，并将其作为模型系统应用于系统地研究这些参数对瞬态传输过程的影响。不对称带电聚合物纳米通道表现出几个显著的特性，例如离子流整流、离子选择性和通过外部触发（如pH值、温度、光或离子浓度）的离子流门控。其中，在定义明确的导电“栅极”上施加外部电压可以局部修改临界长度（德拜层厚度和杜欣长度），并且构成了技术应用中最合适和最有前途的解决方案。在这个项目中，聚合物单纳米通道将被导电金层和多孔金修饰，以实现金表面的“电压充电”。这将使我们能够研究离子和质量输运如何受到德拜层厚度和杜欣长度的外部调制的影响。特别是，计划中的实验将使我们能够使用不同的纳米通道配置（例如，镀金纳米通道和纳米通道内的多孔金）应用时间相关的电压信号，系统地改变实验参数（通道几何形状和尺寸，电解质成分和浓度，电压信号的幅度和频率）。电解质的选择将基于具有不同电荷和/或扩散率的离子的存在。这些实验对于实现理论预测的瞬态纳米孔和未来在更有效的膜分离过程中的应用尤为重要。因此，在第一阶段，该项目将重点研究和理解使用单个基于金的纳米通道的随时间的传输特性。在第二阶段，该技术将应用于多通道膜和特定的分离过程。

In the project single polymer track-etched nanochannels with tailored geometry, diameter, length, and surface charge will be fabricated and applied as model systems to systematically study how transient transport processes are influenced by each of these parameters. Asymmetric charged polymer nanochannels exhibit several remarkable properties, such as e.g., ion current rectification, ion selectivity, and ion current gating via external triggers such as pH value, temperature, light, or ion concentration. Among these, applying an external voltage to a well-defined conductive “gate” enables the local modification of the critical lengths (Debye layer thickness and Dukhin length), and constitutes the most suitable and promising solution for technological applications. In this project, polymer single nanochannels will be modified with conductive gold layers and porous gold to enable "voltage charging" of the gold surface. This will allow us to investigate how ion and mass transport are influenced by the external modulation of the Debye layer thickness and Dukhin length. In particular, the planned experiments will enable us to apply time-dependent voltage signals using different nanochannel configurations (e.g., Au-coated nanochannels and porous Au inside the nanochannel), varying the experimental parameters systematically (channel geometry and size, electrolyte composition and concentration, amplitude, and frequency of the voltage signal). The choice of the electrolyte will be based on the presence of ions with different charges and/or diffusivities. These experiments are particularly relevant for the realization of the theoretically predicted transient nanopores and future applications in more efficient membrane separation processes. Thus, in phase 1, the project will focus on studying and understanding the time-dependent transport properties using single Au-based nanochannels. In phase 2, this know-how will be applied to multi-channel membranes and specific separation processes.