近年來，由於微全分析系統(uTAS)擁有可減少生產費用、使用試劑量以及功率耗費等等優點，因此在化學與生物分析系統應用上受到很大的重視。其中，微流體系統是一項極為重要的發展主題，其發展的關鍵元件包括：微幫浦、微流閥、微混合器、微分離器等。針對微幫浦而言，電動式微幫浦因具有無需可動的機械元件、簡單的設計與製程以及可驅動大範圍導電度的工作流體，因此常被應用於化學/生物實驗上。然而，不論是高直流電壓或低交流電壓致動的電動式微幫浦都會有電解氣泡產生，此電解現象將會縮短微幫浦的工作壽命。故本研究之目的在於發展一個無電解氣泡產生的交流電動式微幫浦，其利用非對稱式電容調變的微電極結構來推動流體流動。此非對稱電容調變的微電極結構能夠提高最大流速的特徵頻率，使得有效降低電解氣泡的發生。
　　此非對稱電容調變的微幫浦係利用一指間狀微電極陣列，其部份區域沉積一SiO2介電層，利用其不對稱的庫倫靜電力造成一等向的流體流動。並經由CFDRC軟體模擬結果得之確實有良好推動流體的效果。在本研究中，實驗量測的流速是為跟供給電壓、供給訊號頻率、電解質濃度、介電層厚度等呈現一函數關係。在我們驗證設計概念的測試元件下，量測的流速可達290 um/s，其施加電壓為10 Vpp。另外，考慮電雙層鬆弛效應的頻率相依流速之數學模型也已被推導及詳加討論。在本論文裡，我們描述了設計概念、電腦模擬、微製程、實驗結果以及數學模型去論證我們所提出的無氣泡、非對稱電容調變之電動式微幫浦設計。

Recently, micro-total-analysis-systems (uTAS) have received a great deal of attention owning to their ability to revolutionize chemical and biological analysis systems by reducing costs, reagent volumes and electrical power consumption. A microfluidic analysis system is a very important subject, and it could contain several microfluidic components such as micropumps, microvalves, micromixers, and microseparators. For micropumps, electrokinetic micropumps are often applied in chemical/bio experiments. The advantages of electrokinetic micropumps over other micropumps are without the moving mechanical parts, with much simpler designs/fabrication, and they could pump the fluids with a wide range of conductivity. However, these electrokinetic micropumps do not effectively prevent the occurrence of electrolytic bubbles even at a low applied ac potential. Therefore, the objective of this research is to develop a bubble-free ac electrokinetic micropump via such an asymmetric capacitance-modulated microelectrode array. This proposed asymmetric modulation design could shift the optimal frequency of maximum velocity to a higher frequency to minimize the electrolysis bubble generation to enhance the performance.
The asymmetric capacitance-modulated microelectrodes are made of an interdigitated Al electrode array and part of individual electrode surface is modulated/deposited with SiO2 dielectric layer. The CFDRC simulation results verify that we could control the fluid flow via the proposed designs. The pumping velocity is measured as a function of the applied voltage, the signal frequency, the electrolyte concentration and the thickness of dielectric layer. A maximum velocity is observed up to 290 um/s in 5mM electrolyte with the applied potential of 10 Vpp in our prototype device. Furthermore, a theoretical model incorporating the effect of double-layer relaxation has also been developed to allow a physical understanding of our proposed micropumps. In this research, we describe the design, simulation, fabrication, experimental results and theoretical model to characterize and demonstrate the performance of the proposed bubble-free ac electrokinetic microfluidic pump.

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