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系統識別號 U0026-0812200915181665
論文名稱(中文) 介電潤濕元件接觸角飽和現象之探討
論文名稱(英文) A Study on Saturated Contact Angle in Electrowetting-on-Dielectric (EWOD) Device
校院名稱 成功大學
系所名稱(中) 工程科學系碩博士班
系所名稱(英) Department of Engineering Science
學年度 97
學期 2
出版年 98
研究生(中文) 戴佑全
研究生(英文) You-cyuan Dai
學號 n9696427
學位類別 碩士
語文別 中文
論文頁數 63頁
口試委員 口試委員-駱文傑
口試委員-傅龍明
口試委員-李國賓
指導教授-楊瑞珍
中文關鍵字 聚二甲基矽氧烷  介電潤濕  飽和  微液滴  接觸角 
英文關鍵字 Electrowetting-on-dielectric (EWOD)  Micro-droplet  Saturation  Polydimethysiloxane (PDMS)  Contact angle 
學科別分類
中文摘要 本論文將以實驗及理論兩部份來探討微液滴在介電潤濕(Electrowetting-on-dielectric , EWOD)此操作條件下其接觸角飽和之行為。本研究中之介電潤濕晶片製作之步驟為:先將利用熱蒸鍍系統在青板玻璃(Soda-lime glass)表面鍍上鋁及鉻兩種金屬成為一電極層,再利用旋轉塗佈機塗佈高分子材料聚二甲基矽氧烷(polydimethysiloxane , PDMS)於電極層上,成為介電潤濕晶片之介電層及疏水層。本研究將探討五種介電層及疏水層厚度之介電潤濕行為,其厚度分別為17 μm、31 μm、68 μm、113 μm及234 μm。而在介電潤濕現象之理論分析方面,將包含兩部份:第一部份以最小能量之觀點(介面位能、重力位能及電能)進行分析,第二部份則以等效電路迴路分析探討微液滴的接觸角與提供電位兩者之間的關係。在本研究之實驗結果可知在不同介電層厚度其接觸角飽和之角度皆近似於 。 在介電潤濕現象下,楊-李普曼(Young-Lippmann)方程式已無法描述微液滴接觸角飽和與所施加電壓之行為,本研究推測造成接觸角飽和行為之原因為高分子材料聚二甲基矽氧烷發生介電潰堤現象。當提供的電場強度超過高分子材料聚二甲基矽氧烷之介電強度,此時高分子材料之介電性質將會改變,而造成高分子材料聚二甲基矽氧烷將產生導體性質而造成電流溢漏,故本研究之實驗結果中發現當提供之電位達到臨界電壓時,將產生電流溢漏之現象,並且定義出此時臨界電場強度為高分子材料聚二甲基矽氧烷之介電強度,介電強度也將隨著介電層厚度增加而降低,此趨勢與介電材料相關文獻中相符合。
英文摘要 This study presents the experimental and theoretical investigations into the issue of the micro-droplet saturated contact angle in electrowetting-on-dielectric (EWOD). The EWOD chips were fabricated by the following processes. First, the aluminum/chromium electrodes were plated on a soda-lime glass using the thermal evaporation. Then, the polydimethysiloxane (PDMS) was adopted to form the dielectric/hydrophobic layer over the electrode using the spinning coater. There are five different thicknesses of dielectric/hydrophobic layer (17 μm, 31 μm, 68 μm, 113 μm and 234 μm) were fabricated to study the EWOD. In theoretical analysis, the principle of minimum energy (e.g. interfacial potential, gravitational potential and electrical energies) and the electrical circuit analysis were both adopted to investigate the relationship between the contact angle of micro-droplet and the applied voltage. The experimental results showed that the saturated contact angles of micro-droplet for the different thicknesses of dielectric/hydrophobic layer are all approximately 57°. The Young-Lippmann equation fails to describe why the saturated contact angle of micro-droplet occurs in EWOD. We infer that the dielectric breakdown may be a possible reason to interpret this physical phenomenon. When the externally applied electric field strength is larger than the dielectric strength of the material (i.e. PDMS), the dielectric or electrical properties of the material will break down. The material becomes a partial conductor and results in the current leakage. In our experimental measurements, we find that the current leakage occurs at the critical applied voltage of the saturated contact angle. Further, we identify that the critical electric field strength as the dielectric strength of the material. We find that the dielectric strength decreases as the thickness of dielectric/hydrophobic layer is increased. This trend is consistent with the dielectric strength measurements of the dielectric materials in literatures.
論文目次 中文摘要 I
Abstract II
致謝 III
目錄 V
表目錄 VIII
圖目錄 IX
符號表 XI
第1章 緒論 1
1.1. 前言 1
1.2. 微液滴之操控方式 1
1.2.1. 熱能 3
1.2.2. 光能 3
1.2.3. 電能 4
1.2.4. 化學能 5
1.3. 介電層上之電潤濕現象 5
1.4. 研究動機及目的 7
第2章 材料與製程 8
2.1. 介電潤濕晶片製作 8
2.1.1. 玻璃 9
2.1.2. 電極 9
2.1.3. 介電層及疏水層塗佈 10
2.2. 實驗設置 12
2.2.1. 直流電源供應器 12
2.2.2. 高速影像擷取器 13
2.2.3. 顯微鏡組 13
2.2.4. 影像分析軟體 13
2.2.5. 低電流量測儀器 13
第3章 介電潤濕現象 14
3.1. 序言 14
3.2. 數學模型 15
3.2.1. 介面位能 16
3.2.2. 重力位能 17
3.2.3. 電能 18
3.3. 電路分析 20
3.3.1. 溶液 21
3.3.2. 電雙層效應 22
3.3.3. 介電層 23
3.3.4. 綜合討論 25
第4章 結果與討論 27
4.1. 接觸角量測 27
4.2. 飽和時臨界電壓 28
4.3. 電流值 30
4.4. 討論 31
第5章 總結及未來展望 33
附錄A 34
附錄B 36
附錄C 58
參考文獻 59
自述 63
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