臺灣博碩士論文加值系統

本論文的主要探討微液珠於微流體系統中的運動及應用。我們藉由微流道設計以及流量的調控來操控微珠大小及型態以配合不同的實驗需求。
本論文有四部份。第一部份，我們觀察油珠在具不同親疏水性質的Y型分岔微流道中之運動行為，發現油珠因為兩分岔管的濕潤性質不同而偏向親水端移動，且油珠的運動模式可隨流量不同而改變。我們同時發現存在一組最佳流量使油珠往親水端支管偏移的傾向為最大。我們藉由尺度分析來評估相關效應的相對大小，同時發現不同油珠之偏移模式主要是由於表面改質效應與油珠間流體力學效應競爭下的結果。此系統對於不同親疏水性的混合微粒系統之分離、流體式邏輯閘以及非接觸式分子探針可提供有效指引。
論文的第二部份，我們嘗試利用電場來驅動微珠運動。我們觀察發現微珠會朝電場相反方向移動。我們推測造成此現象的原因是因為微珠與管壁間的薄膜層會有電滲流發生。然而，因為微珠界面與管壁的表面電荷不同，電滲流速度的差異會造成一與電滲流(電場)方向相反的壓力迴流，因而帶動微珠移動。
論文的最後兩部份則致力於開發拉伸DNA分子的新方法。我們利用微流道系統產生一扁長狀微珠，並於微珠與管壁間形成一厚度相當細薄的次微米薄膜層。而此次微米薄膜層具有以下二特性：第一、此微米薄膜層具有能量障礙上的限制，以至於DNA分子必須改變其結構來降低自由能方可進入薄膜層。第二、由於次微米薄膜層入口端厚度急遽的縮減，此可大幅提高薄膜層之剪應力或電場，我們則利用此特性來達到有效拉伸DNA分子的目的。於論文的第三及第四部份中，我們分別利用壓力及電力方式使DNA分子於薄膜層內產生動態拉伸。我們不僅討論DNA分子於不觀測區域或外力作用下型態上如何變化，同時探討DNA分子於提濃及分離應用上的可能性。

In this thesis, we study the motion of microdroplets and explore their applications to microfluidic systems. Through control of flow rates in concert with appropriate channel designs, we are able to generate microdroplets in different sizes and shapes for desired processes.
There are four parts in this thesis. In Part I, we examine the motion of microdroplets in a bifurcating microchannel with hydrophilic and hydrophobic branches. We find that the drops tend to be re-directed towards the hydrophilic end due to the wettablility difference between the two branches . Such asymmetric motion, however, can exhibit a variety of behaviors, depending on applied flow rates. In addition, there exists an optimal flow rate at which the tendency toward the hydrophilic end is maximal. With the aid of a scaling analysis, we identify that the observed phenomena are attributed to the competition between the surface-directed effects and inter-droplet hydrodynamic interactions. This system has potential applications to separation of a suspension of fluid particles of different affinities to the channel surface. It can also serve a fluidic gate or non-contact intermolecular probe.
In Part II, we make an ab initio attempt in driving microdroplets with electric fields. We observe that the drops move against the applied field. The motion could be attributed to backflow pressures induced by the electro-osmotic flow in the thin film region that exists different surface charges between the fluid interface and the channel wall.
The last two parts of this thesis are devoted to developing new microfluidic strategies for dynamic stretch of single-molecule DNA. Here we invoke long, closely-fitted fluid slugs to create submicron films in microchannels. The effects of the submicron films are twofold. On the one hand, they create energy barriers or confinement effects, so that a DNA must change its conformation for minimizing the free energy as entering the film. On the other hand, due to dramatic reduction of dimensions, thin films set up large shears or fields and hence provide a more robust means to stretch DNA therein. In Part III and IV, we employ hydrodynamic pressures and electric forces, respectively, to examine the corresponding dynamic behaviors of stretched DNA within the films. We not only demonstrate how the conformation of DNA changes in response to various constraints or applied forces, but also discuss possible applications for concentration and separation of DNA molecules.

摘要i
Abstractii
致謝iii
目錄iv
表目錄ix
圖目錄x
符號說明xix

第一章 緒論1
1.1 研究背景1
1.2 文獻回顧2
1.2.1微液珠(microdrops)之微流道設計2
1.2.2微液珠於微流體上之應用 3
1.2.3應用表面改質效應之微流體控制技術4
1.2.4 DNA動態拉伸行為之相關研究6
1.3 研究動機7
第二章 微流道製作與組裝19
2.1 光罩設計19
2.2 光微影 (Photolithography) 製程20
2.2.1晶片清洗20
2.2.2塗佈光阻(Spin Coat)20
2.2.3軟烤 (Soft Bake)21
2.2.4曝光 (Exposure)22
2.2.5 曝後烤 (Post Expose Bake)23
2.2.6顯影 (Development)24
2.2.7硬烤 (Hard Bake)24
2.2.8測量厚度25
2.3 微流道製作25
2.3.1材料 25
2.3.2微流道模型製作26
2.4 微流道裝置組裝 27
2.4.1接合 27
2.4.2管件組裝28
2.4.3 PDMS表面改質 29
2.5 實驗設備30
第三章 油珠於不同親疏性之分岔微流道系統運動特性之探討37
3.1 實驗38
3.1.1微流道裝置38
3.1.2微流道表面改質技術39
3.1.3實驗溶液41
3.1.4硬體架構42
3.1.5實驗步驟42
3.1.6相關實驗細節43
3.1.6.A 消彌不穩定因素43
3.1.6.B 出口條件控制44
3.1.6.C 實驗觀測及紀錄47
3.1.6.D 實驗操作時間考量48
3.2 表面改質對油珠運動的影響49
3.2.1完全親水微流道之對照組 49
3.2.2具親疏水性差異之微流道 52
3.3 水溶液流量(Q)的影響53
3.3.1寬流道(D=200μm)油珠運動模式53
3.3.2窄流道(D=100μm)油珠運動模式56
3.4 影響油珠運動的機制58
3.4.1影響油珠運動的相關尺度 60
3.4.2影響油珠運動之因素60
3.4.3利用尺度分析討論實驗結果63
3.4.3.A 寬流道(D=200μm)的實驗結果說明63
3.4.3.B 窄流道(D=100μm)的實驗結果說明65
3.5 結論、建議以及未來工作66
第四章 以外加電場方式驅動扁長型油珠於微流道內之運動88
4.1 實驗88
4.1.1微流道裝置88
4.1.2實驗溶液89
4.1.3硬體架構90
4.1.4實驗步驟90
4.1.5相關實驗細節91
4.1.6實驗觀測與紀錄92
4.2 結果與討論92
4.3 結論、建議以及未來工作93
第五章 以應用壓力驅動方式連續產生扁長型液珠系統來操控DNA動態拉伸及相關運動行為之探討99
5.1 實驗100
5.1.1微流道設計100
5.1.2實驗溶液101
5.1.3硬體架構102
5.1.4實驗步驟102
5.1.5相關實驗細節103
5.1.6實驗的觀測與紀錄104
5.1.6.A影像擷取軟體Image-Pro Plus之介紹104
5.1.6.B低倍數物鏡之觀測與紀錄105
5.1.6.C高倍數物鏡之觀測與紀錄106
5.2 水油二相流之流動型態及特徵107
5.2.1水油二相流之流動型態107
5.2.2不同流量條件對油珠長度以及速度之影響108
5.3 流動中的扁長型油珠對DNA分子運動影響的探討 111
5.4 DNA於T型流道中之分叉或水油流動交界處附近之運動行為119
5.5 DNA於管道分叉處附近及大小管徑交接處之運動行為120
5.6 結論、建議以及未來工作121
第六章 利用電泳方式驅動DNA進入扁長型油珠底部薄膜層並且造成動態拉伸之效應151
6.1 實驗152
6.1.1微流道裝置152
6.1.2實驗溶液153
6.1.3硬體架構154
6.1.4實驗步驟154
6.1.5實驗相關細節155
6.2 實驗觀測與紀錄156
6.2.1使DNA分子進入薄膜所需之最小電壓(臨界電壓)之測量157
6.2.2 DNA於扁長型油珠薄膜內的運動行為之觀測158
6.2.3 DNA鬆弛時間(relaxation time)的觀測159
6.3 實驗結果與討論 160
6.3.1臨界電壓(Critical Voltage)的實驗結果160
6.3.2 DNA於扁長型油珠底層薄膜內運動行為之結果160
6.3.3 DNA relaxation time 的實驗結果163
6.3.4在外加電場作用下DNA於拉伸狀態時之外受電力、阻力及移動速度之推導164
6.3.4.A DNA分子結構介紹164
6.3.4.B運動機制的推導165
6.4 結論、建議以及未來工作168
附錄6A185
附錄6B186
第七章 結論188
參考文獻190
自述194

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