纳流体芯片中聚丙烯酰胺纳孔的电化学表征
发布时间：2018-08-08 19:46
【摘要】：微制造的发展为纳流体研究提供了可控的纳米结构,从而为我们对纳米级过程的理解和探索其在化学分析等方面的应用提供一个崭新的机会。本文在纳流体芯片中研究聚合物纳米多孔结构(nanoporous structure, NPS)的电特性。基于电化学阻抗谱(electrochemical impedance spectroscopy, EIS)进行了阻抗检测实验,利用阻抗特征参数分析结构的特征参数。本文主要内容包括：分析了NPS电化学检测的基本理论,建立了NPS检测的等效电路模型。解释了纳流体由于双电层(electric double layer, EDL)厚度与沟道高度比率降低导致的EDL扩散部分的重叠现象。根据电导公式估算了微沟道中的溶液电阻,对电荷转移电阻进行了归一化处理。制作了集成不同交联比纳米多孔结构的纳流控芯片,分析了电解液浓度对阻抗幅值和相位的影响。结果表明低频区,阻抗响应的幅值与KCl浓度大小有关。然而,在高频阶段,幅值的斜率与KCl的浓度几乎没有关系,频率对阻抗响应的影响很小,浓度增大使体系的特征频率增大。从反应动力学角度分析了电极过程步骤。利用阻抗的最大平均值,对不同KCl电解液下的阻抗数据进行标准化处理,发现标准化的阻抗虚部峰值出现于标准化频率约为1时,不同浓度下的阻抗曲线相互重叠。根据电荷转移电阻及时间常数值,研究了NPS电解液浓度与特征参数之间的关系,结果表明,在同一种浓度下,纳米多孔结构交联比差异虽然改变了纳米多孔结构的电阻、纳米多孔结构双电层的电容,但是并没有改变体系弛豫过程的快慢。为了进一步探讨NPS几何特征与阻抗的关系,本文结合前人的对比研究孔径与电荷转移电阻的变化趋势,发现当NPS孔径最小时,电荷转移电阻出现最大值；反之,当NPS孔径最大时,电荷转移电阻出现最小值,说明电荷转移电阻与NPS的特征尺寸有着相互对应关系。整个体系的电极过程是由电荷传递主导,而电荷传输仅受一个活化能控制。本文为进一步研究使用电化学方法表征聚丙烯酰胺纳米多孔结构结构提供了探索性实验基础。
[Abstract]:The development of microfabrication provides a controllable nanostructure for nanofluid research, which provides a new opportunity for us to understand nanoscale processes and explore their applications in chemical analysis. In this paper, the electrical properties of polymer nano-porous (nanoporous structure, NPS) are studied in nanoscale chips. The impedance measurement experiment based on electrochemical impedance spectroscopy (electrochemical impedance spectroscopy, EIS) was carried out, and the characteristic parameters of the structure were analyzed by impedance characteristic parameters. The main contents of this paper are as follows: the basic theory of NPS electrochemical detection is analyzed and the equivalent circuit model of NPS detection is established. This paper explains the overlap of diffusion part of EDL due to the decrease of the ratio of double layer (electric double layer, EDL) thickness to channel height. The solution resistance in the microchannel is estimated according to the conductance formula, and the charge transfer resistance is normalized. Nanofluidic chips with different cross-linking ratios were fabricated and the effects of electrolyte concentration on impedance amplitude and phase were analyzed. The results show that the amplitude of impedance response is related to the concentration of KCl in the low frequency region. However, at the high frequency stage, the slope of amplitude is almost independent of the concentration of KCl, and the frequency has little effect on the impedance response, and the increase of the concentration increases the characteristic frequency of the system. The electrode process steps are analyzed from the point of view of reaction kinetics. By using the maximum average impedance, the impedance data under different KCl electrolytes were standardized. It was found that the peak value of the normalized impedance imaginary part appeared at about 1 normalized frequency, and the impedance curves of different concentrations overlapped each other. According to the charge transfer resistance and time constant, the relationship between the concentration of NPS electrolyte and the characteristic parameters is studied. The results show that the difference of cross-linking ratio of nano-porous structure changes the resistance of nano-porous structure under the same concentration. The capacitance of double layer of nano-porous structure does not change the relaxation process of the system. In order to further study the relationship between the geometric characteristics of NPS and the impedance, this paper studies the variation trend of aperture and charge transfer resistance in combination with the previous comparison. It is found that the maximum value of charge transfer resistance occurs when the aperture of NPS is the smallest. When the aperture of NPS is maximum, the charge transfer resistance is minimum, which indicates that the charge transfer resistance has a corresponding relationship with the characteristic size of NPS. The electrode process of the system is dominated by charge transfer, which is controlled by only one activation energy. This paper provides an exploratory experimental basis for the further study on the characterization of polyacrylamide nanoporous structure by electrochemical method.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O657.1;TB383.1
本文编号：2172865
[Abstract]:The development of microfabrication provides a controllable nanostructure for nanofluid research, which provides a new opportunity for us to understand nanoscale processes and explore their applications in chemical analysis. In this paper, the electrical properties of polymer nano-porous (nanoporous structure, NPS) are studied in nanoscale chips. The impedance measurement experiment based on electrochemical impedance spectroscopy (electrochemical impedance spectroscopy, EIS) was carried out, and the characteristic parameters of the structure were analyzed by impedance characteristic parameters. The main contents of this paper are as follows: the basic theory of NPS electrochemical detection is analyzed and the equivalent circuit model of NPS detection is established. This paper explains the overlap of diffusion part of EDL due to the decrease of the ratio of double layer (electric double layer, EDL) thickness to channel height. The solution resistance in the microchannel is estimated according to the conductance formula, and the charge transfer resistance is normalized. Nanofluidic chips with different cross-linking ratios were fabricated and the effects of electrolyte concentration on impedance amplitude and phase were analyzed. The results show that the amplitude of impedance response is related to the concentration of KCl in the low frequency region. However, at the high frequency stage, the slope of amplitude is almost independent of the concentration of KCl, and the frequency has little effect on the impedance response, and the increase of the concentration increases the characteristic frequency of the system. The electrode process steps are analyzed from the point of view of reaction kinetics. By using the maximum average impedance, the impedance data under different KCl electrolytes were standardized. It was found that the peak value of the normalized impedance imaginary part appeared at about 1 normalized frequency, and the impedance curves of different concentrations overlapped each other. According to the charge transfer resistance and time constant, the relationship between the concentration of NPS electrolyte and the characteristic parameters is studied. The results show that the difference of cross-linking ratio of nano-porous structure changes the resistance of nano-porous structure under the same concentration. The capacitance of double layer of nano-porous structure does not change the relaxation process of the system. In order to further study the relationship between the geometric characteristics of NPS and the impedance, this paper studies the variation trend of aperture and charge transfer resistance in combination with the previous comparison. It is found that the maximum value of charge transfer resistance occurs when the aperture of NPS is the smallest. When the aperture of NPS is maximum, the charge transfer resistance is minimum, which indicates that the charge transfer resistance has a corresponding relationship with the characteristic size of NPS. The electrode process of the system is dominated by charge transfer, which is controlled by only one activation energy. This paper provides an exploratory experimental basis for the further study on the characterization of polyacrylamide nanoporous structure by electrochemical method.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O657.1;TB383.1
【参考文献】
相关期刊论文 前1条
1 徐征;李永奎;王俊尧;刘冲;刘军山;陈莉;王立鼎;;一种新颖的微纳流体器件制造方法与痕量富集应用[J];分析化学;2014年02期
，本文编号：2172865
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