Experimental Investigation of Flow Fields Inside Microchannel Devices

• Main Authors: Lai, Chih-Min, 賴智敏
• Other Authors: Huang, Chih-Yung
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/72712248844337714398

碩士 === 國立清華大學 === 動力機械工程學系 === 99 === 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 ?慆 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.