本研究利用介電潤濕現象(Electro-Wetting-on-Dielectric, EWOD)設計並製作出一個低操作電壓之數位液滴(Digital Microfluidics)操作平台，以數位液滴方式進行微流體操控，此一優點為晶片上不需外加動力來源，僅利用電路操控微液滴，解決傳統微流體晶片所需外加可動元件與洩漏問題等缺點為主要目標。

　　在數位液滴控制方面，嘗試製備高介電材料(High K Materials)薄膜及超疏水(Super-Hydrophobic)材料薄膜，以降低操作電壓。本研究成功的利用高介電常數薄膜(Si3N4, Ta2O5, Ba0.5Sr0.5TiO3)，並利用矽油減少液滴與鐵氟龍表面之遲滯現象，將操作電壓降低至12伏特，進行數位液滴之四種基本流體操作：傳輸(Transport)、產生(Create)、分離(Cut)及合併(Merge)。

　　在聚合酶連鎖反應(Polymerase Chain Reaction, PCR)部分，所設計之微型溫度控制器利用白金之電阻溫度係數(Temperature Coefficient of Resistance, TCR)在0℃至100℃的範圍內，電阻值呈線性分佈之特性，於晶片上製作一微型溫度感測器(Micro Temperature Sensor)與微型加熱器(Micro Heater)，搭配一閉迴路溫度控制電路，精確控制聚合酶連鎖反應之循環溫度。

　　此一整合型晶片將聚合酶連鎖反應試劑(PCR Reagnet)與核酸溶液以低操作電壓之數位液滴進樣、傳輸、混合後，藉由於晶片上所設計之親、疏水區介面，使得混合完成後之液滴因該介面之表面張力梯度（Surface Tension Gradient）移動至微型溫度控制區內。傳送完成後，利用所設計之微型溫度控制器進行聚合酶連鎖反應所需之三個階段性精確的溫度控制與快速的溫度循環，可增幅出基因的特徵片段，完成登革熱第二型病毒之互補式核酸序列（Dengue II Virus cDNA, 511bps）之增殖。

　　應用此一整合型晶片做疾病偵測有下列優點：(1) 自動化準確且快速操控樣品及反應試劑，並節省70%反應試劑 (2) 快速的升降溫縮短50%的反應時間 (3) 低操作電壓系統，降低電壓對於生物檢體之影響，並避免複雜電路控制元件 (4) 此一系統除電路外，不需外加任何元件即可完成低操作電壓數位液滴操控、聚合酶連鎖反應，成功地去除了微幫浦、微閥門等可動元件，以及加熱時外加溫度感測器與加熱風扇等元件。

　　本研究成功地應用上述設計，整合一新型低操作電壓之數位式微液滴傳輸與疾病快速偵測生物晶片，其包含 (1) 12伏特操控數位式微流體及(2) 9伏特微型溫度控制 二系統，整合於一便宜且生物相容性高的玻璃基材上，並針對登革熱第二型病毒之互補式核酸序列進行聚合酶連鎖反應。證實以數位液滴操控方式應用於實驗室晶片(Lab-on-a-Chip, LOC)之可行性。我們期待將數位式微液滴實驗室晶片的整合，能帶給生物醫學領域更多應用及重大貢獻。

　　This study designs and fabricates a digital microfluidic platform with a low operation voltage by utilizing electro-wetting-on-dielectric (EWOD) effect. All the microfluidic movements are realized bet　ween two parallel plates on this platform. The digital microfluidics chips (DMC) could make liquids digitalized, allowing for the transportation of droplets without moving micromechanical components in the device. Most fluidic operations such as sample transporting, creation, cutting and merging can be carried out on the chips using discrete droplets. The DMC does not require pumps, mixers and valves as in traditional microfluidic systems.

　　The droplet motion can be manipulated by using surface tension gradient generated by EWOD, which could control of the wettability of liquids on dielectric thin film surfaces while electric potential is applied. This study tested several high K materials such as BST (Ba0.5Sr0.5TiO3), Ta2O5, Si3N4, Parylene and silicon-dioxide (SiO2). By using the Young-Lippmann equation, reducing the operating voltage of EWOD could be realized. Meanwhile, the hysteresis effect of contact angles between the droplet and the Teflon surface could be reduced by filling silicone oil into the parallel open channel. Therefore, the four fundamental microfluidics operations, transport, creation, cutting, and merging, can be performed with a lower voltage of 12 V.

　　Polymerase chain reaction (PCR) is a popular technology in molecular biology. A micro temperature sensor and micro heaters have been integrated into the EWOD chip to allow for PCR operation, which is dependent on three precise temperature steps. Utilizing the characteristics of a temperature with a constant TCR (Temperature Coefficient of Resistance), this study designed a closed-loop temperature controller. The micro temperature sensor, micro heaters, and smaller reagent volume allow for a heating rate of 38.0 degrees per second and a cooling rate of 7.9 degrees per second, thus enabling for faster completion of the PCR cycles. The micro temperature sensor, micro heaters are controlled by a commercial programmable chip (AT90S8535). This chip successfully achieved 25 thermo cycles PCR for the genes of Dengue II Virus cDNA in 55 minutes.

　　Utilizing micro-electro-mechanical-system (MEMS) fabrication technology, the digital microfluidics operation system and micro temperature controller could be successfully integrated into a cheap and biocompatible glass substrate to allow automated rapid infectious disease detection. By using EWOD effect, the chip could make liquids digitalized, permitting droplets to be quickly and precisely transported and mixed without any moving components. This study also designed a new hydrophilic-hydrophobic interface to induce the surface tension gradient to transport the mixed droplets into the reaction chamber. The Dengue II Virus cDNA polymerase chain reaction was also performed on the developed chip which was used to detect microorganism genes by amplifying the target sequence (511bps) with PCR. This study confirmed the feasibility of the PCR with the digital microfluidics operation.

　　The integrated DMC has several advantages for infectious disease detection including (1) low voltage operation DMC, (2) 70% less sample and reagent consumption (3) 50% shorter detection time due to faster thermal cycling, and (4) high accuracy and reproducibility due to a simple and reliable fabrication process. The study successfully applied the concept of Digital Micro Fluidics to the Lab-on-a-chip. The developed microchip will be of great benefit in the future genetic analysis and infectious disease detection.

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