Determining nanocapillary geometry from electrochemical impedance spectroscopy using a variable topology network circuit model.
Determining nanocapillary geometry from electrochemical impedance spectroscopy using a variable topology network circuit model.
复制标题
使用可变拓扑网络电路模型从电化学阻抗谱确定纳米毛细管几何形状。
DOI：
10.1021/ac102236k
复制
发表时间：
2011
影响因子：
7.4
通讯作者：
Talaga,DavidS
中科院分区：
文献类型：
--
作者：
VitarelliJr,MichaelJ;Prakash,Shaurya;Talaga,DavidS
固态纳米孔和纳米毛细管在各种应用中得到越来越多的应用，包括 DNA 测序、合成纳米孔、下一代水净化膜和其他纳米流体结构。本文开发了使用电化学阻抗谱来确定纳米毛细管的几何形状。推导了网络等效电路元件，其中包括纳米毛细管内部电容双层的影响以及变化的纳米毛细管半径的影响。这种可变拓扑函数在某些限制下类似于有限 Warburg 阻抗。导出了几种不同纳米毛细管形状的分析表达式。对函数进行评估以确定阻抗信号将如何随着不同的纳米毛细管纵横比和毛细管中心的不同收缩或膨胀程度而变化。接下来，在不同浓度的电解质下测量纳米毛细管阵列膜的复阻抗谱，以将纳米毛细管双层电容的影响与纳米毛细管几何形状的影响分开。纳米毛细管的可变拓扑等效电路元件模型用于等效电路模型，其中包括膜和测量装置的贡献。所得值与制造商指定的纳米毛细管几何形状公差一致。事实证明，电化学阻抗谱可以用作原位测定纳米毛细管几何形状的工具。
Solid-state nanopores and nanocapillaries find increasing use in a variety of applications including DNA sequencing, synthetic nanopores, next-generation membranes for water purification, and other nanofluidic structures. This paper develops the use of electrochemical impedance spectroscopy to determine the geometry of nanocapillaries. A network equivalent circuit element is derived to include the effects of the capacitive double layer inside the nanocapillaries as well as the influence of varying nanocapillary radius. This variable topology function is similar to the finite Warburg impedance in certain limits. Analytical expressions for several different nanocapillary shapes are derived. The functions are evaluated to determine how the impedance signals will change with different nanocapillary aspect ratios and different degrees of constriction or inflation at the capillary center. Next, the complex impedance spectrum of a nanocapillary array membrane is measured at varying concentrations of electrolyte to separate the effects of nanocapillary double layer capacitance from those of nanocapillary geometry. The variable topology equivalent circuit element model of the nanocapillary is used in an equivalent circuit model that included contributions from the membrane and the measurement apparatus. The resulting values are consistent with the manufacturer’s specified tolerances of the nanocapillary geometry. It is demonstrated that electrochemical impedance spectroscopy can be used as a tool for in situ determination of the geometry of nanocapillaries.