臺灣博碩士論文加值系統

本研究利用微機電技術，且使用陽離子選擇性膜(Nafion)替代奈米管道製作出可用於樣品預濃縮的微流體晶片。當施加電場於微流體晶片時，由於陽離子選擇性膜內孔徑的電雙層重疊現象，使得陽離子選擇性膜內形成離子選擇之特性。此特性造成奈米通道內存在陽離子與陰離子的通量差異，導致在微奈米管道介面形成濃度極化之效應，在離子交換膜附近濃度梯度的發生。陽極端可觀察到離子消散區形成，而在離子消散區與電滲流流場交接處有一電場降幅區，利用電場降幅使離子累積，因此在管道中形成一個高濃度的界面，達到濃度預集中之目的。
本論文主旨，在探討陽離子選擇性膜的改質，在傳統陽離子選擇膜(Nafion)內添加氧化石墨烯應用於樣品預濃縮晶片上，藉由氧化石墨烯內自身的官能基，來提高我們預濃縮現象。探討如何提高富集效果的可行性，進而達到最佳化。因此，我們分別討論氧化石墨烯與Nafion的混合比例和不同氧化石墨烯的含量，找出彼此參雜的最佳比例及濃度，再與單純的Nafion材料，進行比較。由實驗結果可發現，我們利用30 V電壓差進行實驗，在直通管道下，利用0.5 wt %氧化石墨烯與Nafion以體積比三比一進行調配，所製造出的離子選擇膜，可聚集螢光在30分鐘裡達到60倍，優於傳統Nafion的40倍。

In this thesis, we utilized the micro-electromechanical technique using Nafion instead of a nanochannel in microfludic chips for use in sample preconcentration. When an electric field is applied to the micro-nano chip, the cation selective membrane (Nafion) has the characteristic of cation and anion flux difference due to the overlapped double layer effect in the nanochannel, which results in the concentration polarization phenomenon at the micro- and nano-interface. The concentration polarization phenomenon causes a concentration gradient to occur near the membrane. On the anodic side, the ion depletion zone can be induced by applying a voltage. The ion accumulation is the result of the difference in electro-migration at the boundary between the depletion zone and electroosmotic flow. Therefore, it creates a high concentration interface in the channel to achieve ion concentration.

The aim of this study was to explore a modified cation selective membrane by adding graphene oxide (GO) to a traditional Nafion membrane used in preconcentration chips. It was found that the GO functional group, enhanced our preconcentration phenomenon. We also discuss how to enhance the feasibility, after which we optimize the preconcentration effect in this modified membrane. To this end, we respectively mix GO and Nafion with different volume ratios and GO content (%) to find the optimal volume ratio and concentrations. Then, we compare GO/Nafion with Nafion alone. Based on the experimental result, we applied a voltage of 30 V in a straight microchannel. In using 0.5 wt % GO to mix with Nafion, the GO volume was three times more than that of the Nafion. These kinds of GO/Nafion ion selectivity membranes can achieve a 60-fold increase in preconcentration factor within 30 min, which is superior Nafion membranes that offer a 40-fold increase.

Abstract I
中文摘要 III
致謝 IV
Contents V
List of Figures VIII
Abbreviation XIV
Nomenclature XVI
Greeks XVII
Chapter 1 Introduction 1
1.1 Introduction 1
1.2 MEMS Technology ＆ Microfluidic Biochips 1
1.3 Literature review 3
1.4 Motivation 10
Chapter 2 Electrokinetic Effect 12
2.1 Electrical Double Layer, EDL 12
2.1.1 Overlapped Double Layers 14
2.2 Electroosmotic Flow 15
2.3 Electrophoresis 16
2.4 Concentration Polarization Phenomena 17
Chapter 3 Materials and Methods 21
3.1 Materials and Reagents 21
3.2 Mask 21
3.3 Fabrication of the Integrated Microchip 22
3.3.1 Substrate Pretreatment 23
3.3.2 Photoresist Coating 23
3.3.3 Exposure 23
3.3.4 Development 24
3.3.5 PDMS Casting 24
3.3.6 Oxygen Plasma Bonding 26
3.3.7 Nafion Patterned Process 26
3.4 Nafion-mixed GO Patterned Process 27
3.5 Instrument and Software 28
3.6 Raman spectroscopy 31
3.7 Fourier transform infrared spectroscopy (FTIR) 32
3.8 Microchip Design 32
3.9 Experimental Setup 33
Chapter 4 Results and Discussion 35
4.1 Fluorescein Preconcentration Process 35
4.2 Ion Depletion 37
4.3 Effect of Nafion-membrane on Preconcentration 39
4.3.1 5 wt % Nafion Junction 39
4.4 Effect of Nafion/GO Membrane on Preconcentration 40
4.4.1 Nafion Mixed GO in Different Volume Ratios 41
4.4.2 Different GO Content (%) Mixed with Nafion 44
4.5 Comparison of Nafion with Nafion/GO Membrane in terms of Preconcentration Effect 48
4.5.1 Nafion membrane compared with Nafion/GO membrane 48
4.5.2 Utilized Raman spectra and FTIR to confirm GO/Nafion mixing uniformity 49
4.6 GO functional carboxyl group 52
Chapter 5 Conclusion 53
References 54

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