Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1886
標題: 光碟式旋轉微流體混合之可視化實驗
Visualization Experiments of Compact Disk Microfluidics for Fluid Mixing
作者: 林茂吉
Lin, Mao Chi
關鍵字: rotational microfluids mixing;旋轉微流體混合;Centrifugal Force Coriolis Force;Flow Visualization;離心力 科氏力;流場可視化
出版社: 機械工程學系
摘要: 
本研究在光碟式(CD-like)的壓克力基材上製作出微流道,並利用流場可視化方法,來觀察兩種流體在微米級尺寸下混合的情形。使用的工作流體為氯化鐵水溶液與硫氰化氨水溶液,兩種流體混合之後會呈現深紅色反應,根據流道中顏色的變化來獲得混合效率的好壞依據。整個混合的機制是由離心力跟科氏力交互作用而成,首先由轉動時所產生的離心力來驅動流體,再搭配流道的幾何設計讓流體受到科氏力引起的二次流達成更快速的混合。旋轉實驗晶片利用微機電微影技術以光阻當流道結構層,並利用透明的壓克力當上蓋熱壓密封形成微流道,以進行流場的觀察與混合效率的分析。旋轉流場觀測平台,包括影像擷取系統、旋轉機制、同步攝影機制等。本研究旋轉微流場的拍攝機制,利用計數器結合馬達編碼器的運用,完成旋轉中的微流場影像拍攝。在毛細閥門的流道幾何設計方面,我們發現流道設計在寬度200μm,深度110μm或150μm並搭配適合的擴張角就會有閥門的作用,而且進一步以修正後的理論與實驗作比較,發現趨勢相當穩合。混合實驗觀察到“可能科氏力”對混合的作用,而混合結構處設計一個鰭片的混合效率比設計二個鰭片與三個鰭片還要佳。可是氣泡的影響無法有效的驗證此結果,因此要在可視化機制與流道幾何改良之後,才能夠進一步驗證科氏力的確會增加流體混合的結論。

This study uses the flow visualization method to observe mixing phenomenon of two fluids in the microchannel fabricated on the Compact Disk(CD)-like PMMA substrate. Ferric chloride and ammonium thiocyanate respectively dissolved in the deionized water are used as the working fluids in the experiment. Quantification of mixing efficiency is based on the reaction of the two fluids. The forces acting on the flow field include the centrifugal and Coriolis forces. The centrifugal force pointing in radial direction drives the fluids to flow along the channels. The Coriolis force that may introduce the secondary flow pointing in the direction across the channels is expected to enhance the mixing. Photoresist is employed as the material for fabrication of the channel structure on the CD-like rotating chip. The chip is thermally bounded with PMMA for flow visualization and measurements of the mixing efficiency. The visualization mechanisms are composed of the image acquisition system, a DC motor with encoder, and the in-house synchronizer for capturing the synchronizing images. The passive valves for restraining the capillary force could be realized by designing a channel width of 200μm and a depth of 110μm or 150μm together with a suitable wedge angle. The experimental results on the“capillary-burst valves”are consistent with the theory that has been modified for the present microchannels to take the three-dimensional surface tension effects into account. In the mixing experiments, the pseudo-Coriolis phenomenon is observed inside the channel with fins and the mixing efficiency in the channel with 1-fin is better than that in the channel with 2-fins or 3-fins. The presence of bubbles in the microchannels in the course of the mixing experiments hinders the observation of the Coriolis effects in the present study. Improvements may be achieved by re-design of the channel geometry and the visualization setup .
URI: http://hdl.handle.net/11455/1886
Appears in Collections:機械工程學系所

Show full item record
 

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.