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研究生：	林宣甫 Lin, Shiuan-fu
論文名稱：	藉微米導線及旅波電場產生交流極化效應所引導之動態組裝 Dynamic Assembly Directed by AC Polarization Using Conducting Microwires and Travelling-Wave Electric Fields
指導教授：	魏憲鴻 Wei, Shian-hung
學位類別：	碩士 Master
系所名稱：	工學院 - 化學工程學系 Department of Chemical Engineering
論文出版年：	2009
畢業學年度：	97
語文別：	中文
論文頁數：	173
中文關鍵詞：	微米導線、交流電荷動力流動、串鏈、旅波式電場、電場誘發極化效應
外文關鍵詞：	pearl chains, conducting microwires, ac electrokinetic flow, electric-field-induced polarization, traveling -wave fields
相關次數：	點閱：107 下載：3
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本論文之實驗探討流體及膠體粒子於高頻交流電場下受極化效應的運動行為，其主題分為兩部分：(一)由微米導線所誘發的交流極化現象(第三章)，及(二)DNA分子與膠體粒子於旅波式電場下的運動行為(第四章)。
第三章部分，我們設計一個由微米導線和大導電面所組成的微流體平台。在此配置中導線的作用為線狀電極，可增益電場強度並於導線周圍產生強烈極化效應。我們採用此裝置來觀察流體及懸浮粒子的行為。本實驗分別採用碳線或金線作為線狀電極。碳線系統中，我們發現粒子不僅會在碳線上聚集，某些情形下也會因局部電場梯度而沿著碳線下方之夾縫中移動。
而金線系統下，我們觀察到極化現象會因施加的電壓及頻率而有所差異。首先在低電壓(<30Vpp)時，在高頻10kHz及1MHz下，懸浮粒子會排開遠離金線。我們驗證出此現象並非因為介電泳，而是因電容充電發生於金線與蓋玻片之夾縫所誘發的交流電滲流。我們也發現相鄰極化粒子間因偶極電荷吸引形成的串鏈。此外，亦會產生粒子吸附於金線表面的現象。而在10kHz時，粒子並無產生串鏈。在低頻100Hz及1kHz下，粒子團因快速的交流電滲渦流而於金線周圍產生強烈的聚集盤繞，且粒子團中所出現的串鏈會因渦流影響而產生流體化現象。於高電壓(>30Vpp)時，粒子因極化效應增強而快速地運動。與低電壓條件比較可發現，在高頻1MHz時，強烈的交流電滲渦流破壞串鏈的形成。於10kHz及100kHz我們還觀察到粒子形成帶狀結構。當頻率低於10kHz時，粒子的盤繞作用變得更快且影響範圍更大。而我們也詳細地探討串鏈的現象，並驗證出最小形成串鏈的電場強度與粒子體積分率1/2次方成反比，與推導的理論相符。
第四章部分研究DNA分子與膠體粒子在旅波式電場作用下的運動行為。我們發現DNA分子會隨著施加頻率及流道寬度而沿著電極陣列之特定區域產生聚集。對於膠體粒子系統，我們發現粒子不僅會聚集在電極上，也會在電極邊緣翻轉。傾斜電極陣列對粒子運動行為的影響亦在本文中描述。
本論文的結果可用於以微流控方法操控和組裝膠體粒子及生物分子。

This thesis is experimental investigation on the motion of fluids and colloids induced by polarization effects in high-frequency ac electric fields. This thesis focuses on two subjects: (i) ac polarization phenomena induced by conducting microwires (Chapter 3), and (ii) the motion of DNA and colloids in travelling-wave fields (Chapter 4).
In Chapter 3, we design a microfluidic platform by placing a conducting microwire under a large conducting plane. In this setup the wire acts as a line electrode capable of magnifying electric fields to create intense polarization effects around the wire. We employ this setup to observe how fluids and suspended particles behave. Two types of line electrodes are employed in the experiments: carbon fibers and gold microwires. For the carbon-fiber system, we find that particles can aggregate onto the fiber. In some cases, they can be trapped beneath the fiber and move along it because of local field gradients thereof.
As for the use of gold microwires, we observe a diversity of polarization phenomena, depending on the applied frequency and voltage. We first look at the low-voltage regime (<30Vpp). At high frequencies of 10k and 1MHz, suspended particles can be repelled away from the wire. We identify that it is not due to dielectrophoresis, but rather to ac electroosmotic flow in which capacitive charging occurs in the thin gap between the wire and the surface. We also find that particles can form pearl chains due to the dipole-charge attraction between adjacent polarized particles. In addition, some of particles are found to be attracted onto the wire surface. At 10kHz, particles do not form pearl chains. At low frequencies of 100 and 1kHz, intense swirling of a concentrated particle cloud can occur around the wire due to rapid ac electro-osmotic vortices. In this case, the observed particle cloud appears in the form of pearl chains fluidized by the vortices. In the high-voltage regime (>30Vpp), polarization effects are further enhanced, leading to faster particle motion. At a high frequency such as 1 MHz, in contrast to chaining found in the low-voltage regime, we find that chaining disappears due to the disruption by intense ac electro-osmotic vortices. At 10k and 100kHz, we further observe that particles can form band structures. At even lower frequencies, the particle swirling becomes even faster and the range of the swirling expands. We also put forth to discuss particle chaining in detail. We identify that the threshold field for onset of the chaining is inversely proportional to the square root of the particle volume fraction, in accordance with theory.
In Chapter 4, we study the motion of DNA molecules and colloidal particles under actions of traveling-wave fields. We find that DNA molecules can be focused at certain locations along the electrode array, depending on the applied frequency and the channel width. As for the colloidal particle system, we find that particles can aggregate on the electrode and re-circulate near the electrode edges. The roles of the titled angle of the electrode array on the particle motion are also illustrated.
The findings in this thesis can be applied to manipulation and assembly of colloids or bimolecules using microfluidic devices.

摘要....................................................i
Abstract..............................................iii
誌謝....................................................v
目錄...................................................vi
表目錄..................................................x
圖目錄................................................xii
符號說明.............................................xxvi
第一章 緒論.............................................1
1.1 研究背景............................................1
1.2 交流電荷動力現象....................................2
1.2.1 應用介電泳原理來操控次微米粒子....................2
1.2.2 流體在電場作用下因電荷動力產生的流動行為..........3
1.3 研究動機............................................5
第二章 電荷動力學基本原理..............................13
2.1 電雙層(Electric Double Layer, EDL).................13
2.2 電滲流(Electro-Osmosis, EO)........................15
2.3 電泳(Electrophoresis, EP)..........................16
2.4 介電泳(Dielectrophoresis, DEP).....................17
2.5 交流電滲流(AC Electro-Osmosis, ACEO)...............19
2.6 交流電熱(AC electrothermal, ACET)..................21
第三章 利用微米導線增益極化作用及其誘發膠體聚集與分散之動態現象.....................................................27
3.1 微導線平臺之特點及研究動機.........................27
3.2 微導線平臺組裝.....................................28
3.3 實驗...............................................30
3.3.1 工作溶液.........................................30
3.3.2 實驗步驟.........................................31
3.3.3 相關實驗細節.....................................32
3.3.4 影像處理軟體(Image-Pro)拍攝條件參數設定..........33
3.4 膠體粒子受微米碳纖維導線所產生之交流電場作用下的聚集及分散現象.....................................................35
3.4.1 二氧化矽粒子受交流電場作用之運動行為.............35
3.4.2 混摻不同粒徑粒子的懸浮液受交流電場作用的運動行為.37
3.4.3 膠體粒子於碳纖維線裝置下之運動行為不均勻的現象...38
3.5 膠體粒子受微米金導線所產生之交流電場作用下的聚集及分散現象.....................................................39
3.5.1 在不同電場頻率下極化粒子的聚集及分散行為.........40
3.5.2 粒子於不同電壓之各頻率下聚集及分散的現象整理.....42
3.5.3 粒子由低電壓轉高電壓之1MHz下的運動行為...........43
3.5.4 影響粒子運動的機制與驗證.........................43
3.5.4.A 排開現象之探討.................................44
3.5.4.B 吸附現象之探討.................................47
3.5.4.C 一般串鏈(不受流動影響)現象之探討...............49
3.5.4.D 流體化串鏈(受流動影響)現象之探討...............49
3.5.5 串鏈現象之機理與驗證.............................51
3.5.5.A 理論模式.......................................51
3.5.5.B 測量E*對Φ的關係及理論驗證.....................52
3.5.5.C 串鏈於交流電場作用下受流動之影響...............54
3.6 結論...............................................55
第四章 DNA分子及膠體粒子受高頻旅波式電場所誘發之聚集及分散作用.....................................................98
4.1 於旅波式電場下的傳輸機制...........................98
4.2 微流道系統之製備..................................100
4.3 實驗..............................................101
4.3.1 工作溶液........................................101
4.3.2 實驗步驟........................................102
4.3.3 相關實驗細節....................................104
4.4 DNA分子受旅波式交流電場作用之聚集與分散行為.......105
4.4.1 DNA分子受一般旅波式交流電場作用於寬流道(2000μm)中的運動行為....................................................105
4.4.2 DNA分子受一般旅波式交流電場作用於窄流道(100μm)中之運動行為....................................................107
4.5 膠體粒子受旅波式交流電場作用之聚集與分散行為......108
4.5.1 粒子受一般旅波式交流電場作用於窄流道(100μm)中之運動行為....................................................108
4.5.2 粒子受傾斜旅波式交流電場作用於窄流道(100μm)中之運動行為....................................................110
4.6 結論..............................................112
第五章 結論與建議.....................................137
5.1 結論..............................................137
5.2 改進建議..........................................139
5.3 未來研究方向......................................140
參考文獻..............................................143
附錄A 微電極系統之製作及實驗設備介紹..................145
A.1 微電極晶片製作....................................145
A.1.1 金(Au)電極晶片製作..............................146
A.1.2 氧化銦錫(ITO)電極晶片製作.......................150
A.2 微流道光微影製程..................................151
A.2.1 微流道光罩設計..................................152
A.2.2 晶片清洗........................................152
A.2.3 塗佈光阻........................................153
A.2.4 軟烤(Soft Baking)...............................154
A.2.5 曝光(Exposure)..................................155
A.2.6 曝後烤(Post Expose Baking)......................156
A.2.7 顯影(Development)...............................156
A.2.8 硬烤(Hard Baking)...............................156
A.3 微流道製作........................................157
A.3.1 材料............................................157
A.3.2 微流道模型製作..................................157
A.4 表面改質..........................................158
A.5 實驗設備..........................................159
附錄B 偶極偶極吸引勢能(Dipole-Dipole attraction potential)公式導証....................................................169
附錄C 交流電熱速度(UACET)導証.........................171
自述..................................................173
                                    

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校內：2012-06-02公開
校外：2012-06-02公開

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