- 學位論文
微尺度流場量測與分析
Experimental Investigation of Flow Fields Inside Microchannel Devices
摘要
本論文旨在將螢光分子感測方法與微粒子影像測速方法應用在微流體通道上的研究。其中，螢光分子感測方法提供在微系統中以光化學方式量測系統內整體壓力分佈的技術；而微粒子影像測速方法則提供了一個非侵入式的二維速度場量測工具。傳統上量測微流道系統裡的壓力分佈，須要以相當複雜的製程方式分散地安置壓力量測點；相反的，螢光分子感測方法以簡易的製程選用適當的螢光分子即可提供微流道內全域的壓力分佈。 雖然微螢光分子感測方法已發展10年以上，但將其應用在微系統內做流場量測卻是這幾年較新的議題。所以此技術在微尺度下的研究仍然需要努力。在本研究上，已就螢光分子物理與化學的特性進行分析，搭配不同的化學溶劑，與適當的黏著劑開發出一套可以運用在微流道當中的壓力感測螢光塗料，並且同時建構出測量的方法與機制，以逐點校正的方式修正傳統單點校正方式的不足，有效地增加量測的準確性與有效的量測範圍。本研究利用微直管/微突縮擴管來量測內部流場結構，並對其流場現象加以探討。在以工作流體為去離子水時進行微直管道的速度量測中，定義出PDMS流道在雷諾數為0.37時，其邊界滑移長度大約1.9~3.3 m。當工作流體為空氣時微直管道內的壓力變化與一階滑移邊界的Navier-Stoke方程式解析解相符合。也可藉由壓力分佈觀察到壓縮效應並加以討論。在微突縮擴矩形管實驗中觀察到雷諾數為46的條件下流體在完全發展後經過突縮擴區域處時會在突擴出口兩端造成流體分離，並在出口兩側之角落形成渦旋；流體分離後與壁面再接觸點在突擴下游處3倍方柱高度的位置。本研究得到之微尺度分離流的物理現象分析將有助於在設計生醫晶片中的介質混合與分離之應用。
並列摘要
This study aims to utilize novel molecule based pressure sensors and -PIV techniques in micro fluidic investigations. The molecular based pressure sensor technique provides a straightforward way to carry out pressure measurements inside micro devices without complicated instrumentation and -PIV provides 2-D velocity profiles with non-intrusive method. Conventional experimental techniques in MEMS research can only acquire discrete and limited data points inside the flow field and the instruments are demanding and hard to install. On the contrary, this novel technique can obtain global pressure profiles in a single measurement with straightforward processes. Although molecule based pressure sensors have been used extensively in the past decades, their applications in MEMS research had just started years ago. Works still need to be done to effectively characterize the methodology and application in micro scale. In this study, the physical and chemical properties, different chemical formulations, and various applying methods of molecule based pressure sensors have been investigated, and experimental procedures as well as the calibration method with pixel-by-pixel calibration have been established. Microchannel devices with straight/constriction microchannels have been demonstrated with the concept and further investigated in the physical phenomena in these specific flow fields. Results of this research have been acquired with the slip length around 1.9~3.3 m in a straight PDMS microchannel with aspect ratio 0.67 and the Reynolds number of 0.37, with DI water as working fluid. The non-linear pressure distributions along a straight microchannel have been investigated with air filled inside the channel which show close agreement with analytical solutions calculated with 2-D continuous flow model with first slip boundary condition. Compressibility effect can also be identified through the pressure data. The velocity profiles of flow inside a constricted microchannel have been acquired and presented at the Reynolds number of 46. Vortex structure in the recirculation area around the corner have been observed and discussed, as well as the reattached points which are further downstream with 3 times rib height. With the understanding of separation mechanism at micro scale, further applications can be extended to biomedical engineering for drug mixing or cell separations.
並列關鍵字
無資料參考文獻
延伸閱讀
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