新型雙層被動式微混合器之設計與最佳參數組合

Design and Optimal Parameter Combination of a Novel Double-Layered Passive Micromixer

劉博文(Pao-Wen Liu)

指導教授 ： 陳漢明

國立臺灣大學/工學院/機械工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.11231

摘要

流體在微觀尺度下，因雷諾數極低，多以層流形式流動，由於少了紊流的協助，使得混合大多僅能依靠較沒有效率的擴散現象，因此諸多加快混合進行的設計陸續被提出，以期能改良現有之微混合器效率。
本研究提出一種雙層結構的被動式微混合器，利用構造單純的直通道及斜通道組合，驅使流體產生連續的分支及再結合(Split and Recombine, SAR) 效果，進而有效改善其混合效率。在設計上，本研究將斜通道傾斜角、直通道寬度以及直通道排列方式作為三項設計變數，藉由數值模擬分析各變數對於流場的影響，並尋得最佳參數組合。模擬結果顯示，斜通道傾斜60◦，直通道寬20 μm 且呈順向排列時，可獲得最佳效果，僅需經過497 μm 便可使混合成效指標(Mixing Index, MI) 達到0.9。製程方面，本研究採用有機矽化合物(Polydimethylsiloxane, PDMS) 翻模製法，使用SU-8 負型光阻搭配微影製程於4 吋矽晶圓上形成流道的單層結構，再利用PDMS 翻模、黏合來形成完整雙層結構的流道試片。實驗則使用混有藍色及黃色染劑的去離子水作為工作流體，搭配光學顯微鏡及CCD 攝影機進行觀測。

關鍵字

微混合器 ； 被動式 ； 雙層結構 ； SAR ； 數值模擬

並列摘要

Unlike macroscope, fluid flows in lamination under microscope due to extremely low Reynolds number, which causes mixing so inefficient since the absence of turbulence and fluids mix mainly relying on diffusion. In order to improve the efficiency of the process, abundant of refined design on micromixers were proposed.
This research presents a novel double-layered passive micromixer. Fluid is driven to go through sequential split-and-recombine (SAR) process by the combination of two simple structures: side channel and lateral slant channel. The angle of the slant channel, the width of the side channel, and the arrangement of the side channel are chosen as three design variables. By the aid of numerical simulation, the effect on flow field and the optimized combination of variables are analyzed. The result of simulation shows it only takes 497 μm along flow direction as mixing index (MI) hits 0.9 when the angle of the slant channel is 60 degree, and the side channel with width 20 μm arranging in the forward-form.
The method of Polydimethylsiloxane (PDMS) re-casting is used in the manufacturing process, including laying the single layer of SU-8 negative photoresist structures on the 4” silicon wafer by carrying out photolithography and casting of the PDMS. The proper double-layered microchannel on the chip can then be achieved by bonding two single-layered structure chips together. Deionized water (D.I. water) with blue dye and yellow dye is used as operating fluid, and the optical microscope assembled with a CCD is used for observation.

並列關鍵字

Micromixer ； Passive ； Double-layered structure ； SAR ； Numerical simulation

參考文獻

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