納流體芯片中聚丙烯酰胺納孔的電化學(xué)表征
發(fā)布時間：2018-08-08 19:46
【摘要】：微制造的發(fā)展為納流體研究提供了可控的納米結(jié)構(gòu),從而為我們對納米級過程的理解和探索其在化學(xué)分析等方面的應(yīng)用提供一個嶄新的機會。本文在納流體芯片中研究聚合物納米多孔結(jié)構(gòu)(nanoporous structure, NPS)的電特性。基于電化學(xué)阻抗譜(electrochemical impedance spectroscopy, EIS)進行了阻抗檢測實驗,利用阻抗特征參數(shù)分析結(jié)構(gòu)的特征參數(shù)。本文主要內(nèi)容包括：分析了NPS電化學(xué)檢測的基本理論,建立了NPS檢測的等效電路模型。解釋了納流體由于雙電層(electric double layer, EDL)厚度與溝道高度比率降低導(dǎo)致的EDL擴散部分的重疊現(xiàn)象。根據(jù)電導(dǎo)公式估算了微溝道中的溶液電阻,對電荷轉(zhuǎn)移電阻進行了歸一化處理。制作了集成不同交聯(lián)比納米多孔結(jié)構(gòu)的納流控芯片,分析了電解液濃度對阻抗幅值和相位的影響。結(jié)果表明低頻區(qū),阻抗響應(yīng)的幅值與KCl濃度大小有關(guān)。然而,在高頻階段,幅值的斜率與KCl的濃度幾乎沒有關(guān)系,頻率對阻抗響應(yīng)的影響很小,濃度增大使體系的特征頻率增大。從反應(yīng)動力學(xué)角度分析了電極過程步驟。利用阻抗的最大平均值,對不同KCl電解液下的阻抗數(shù)據(jù)進行標準化處理,發(fā)現(xiàn)標準化的阻抗虛部峰值出現(xiàn)于標準化頻率約為1時,不同濃度下的阻抗曲線相互重疊。根據(jù)電荷轉(zhuǎn)移電阻及時間常數(shù)值,研究了NPS電解液濃度與特征參數(shù)之間的關(guān)系,結(jié)果表明,在同一種濃度下,納米多孔結(jié)構(gòu)交聯(lián)比差異雖然改變了納米多孔結(jié)構(gòu)的電阻、納米多孔結(jié)構(gòu)雙電層的電容,但是并沒有改變體系弛豫過程的快慢。為了進一步探討NPS幾何特征與阻抗的關(guān)系,本文結(jié)合前人的對比研究孔徑與電荷轉(zhuǎn)移電阻的變化趨勢,發(fā)現(xiàn)當NPS孔徑最小時,電荷轉(zhuǎn)移電阻出現(xiàn)最大值；反之,當NPS孔徑最大時,電荷轉(zhuǎn)移電阻出現(xiàn)最小值,說明電荷轉(zhuǎn)移電阻與NPS的特征尺寸有著相互對應(yīng)關(guān)系。整個體系的電極過程是由電荷傳遞主導(dǎo),而電荷傳輸僅受一個活化能控制。本文為進一步研究使用電化學(xué)方法表征聚丙烯酰胺納米多孔結(jié)構(gòu)結(jié)構(gòu)提供了探索性實驗基礎(chǔ)。
[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.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O657.1;TB383.1
本文編號：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.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O657.1;TB383.1
【參考文獻】
相關(guān)期刊論文 前1條
1 徐征;李永奎;王俊堯;劉沖;劉軍山;陳莉;王立鼎;;一種新穎的微納流體器件制造方法與痕量富集應(yīng)用[J];分析化學(xué);2014年02期
，本文編號：2172865
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