本文提出利用圓弧形迴流道連接混合腔形成的微混合器，由寬度大於主流道寬度的擋板以同側的方式配置與主流道構成混合腔。本文使用商用計算軟體模擬微混合器中的流動與混合，配合實驗觀察在微混合器中三維的流動情形，並探討不同幾何參數的影響。同時使用SU-8光阻塗佈於矽晶圓，並曝光以製作微混合器母模，用PDMS翻模並與載玻片接合，接上矽膠軟管與微量式幫浦完成微流體系統；藉共軛焦光譜顯微鏡影像系統觀察混合現象以驗證模擬結果。比較實驗影像與模擬的結果，得知兩者呈現可接受的吻合，並確認迴流道內的離心渦流與混合腔內的擴張渦流同時作用可以促進流體混合。本文還比較本文提出的微混合器與擋板及迴流道交錯配置的微混合器。由模擬的結果觀察到以下現象：(一)在雷諾數(Re)為81時擋板間的距離約為三倍主流道寬之微混合器有較好的混合效率，而在 時擋板間的距離約為兩倍主流道寬之微混合器有較好的混合效率；(二)本文提出的擋板同側配置之微混合器較擋板交錯配置的微混合器，在雷諾數較高時，有更高的混合效率。另外，在本文也探討擋板數目與擋板寬度的影響。

In this work, we propose a micromixer with mixing chambers connected by detour passages. The mixing chambers are formed by baffles wider than the main channel and the baffles are on the same side of the main channel. We examine its mixing performance under various geometric parameters. This work uses commercial codes and experiments to observe the three-dimensional flow in the micromixer. To fabricate the micromixer, first we coat the SU-8 photoresist on a silicon wafer and explosure the SU-8 film to get the micro-structure on the wafer. Then we replicate the mold by PDMS, bond the former with a cover glass and consist the micromixer with soft pipes and syringe pump to complete the microfluidic system. The mixing flow is observed by confocal spectral microscope imaging system to validate the simulation. Comparison of the simulation and experiment results shows reasonable agreement. The Dean vortices in the detours and the expansion vortices in the mixing chamber work together to enhance the fluid mixing. We also compare the performance of the present micromixer and the micromixer with staggered baffles and detours. The simulation results show the following trends. (i) When the Reynolds number (Re) equals to 81 and the distance between each baffles is around triple of the channel width, the micromixer achieves the highest mixing efficiency. When and the distance between each baffles is around twice of the channel width, the micromixer achieves the highest mixing efficiency. (ii) The mixing efficiency of the proposed micromixer is better than that of the micromixer with staggered baffles and detours, especially for the cases with higher Reynolds numbers. The influence of the baffle numbers and the baffle’s width is also investigated.

1. A. Manz, N. Graber and H. M. Widmer, “Miniaturized total chemical analysis systems: a novel concept for chemical sensing,” Sensors and Actuators B: Chemical, Vol. 1, pp. 244-248, 1990.
2. J. H. Tsai and L. Lin, “Active microfluidic mixer and gas bubble filter driven by thermal bubble micropump,” Sensors and Actuators A: Physical, Vol. 97-98, pp. 665-671, 2002.
3. A. O. E. Moctar, Nadine Aubry and John Batton, ”Electro-hydrodynamic micro-fluidic mixer,” Lab on a Chip, Vol. 3, pp. 273-280, 2003.
4. Y. Wang, J. Zhe, B. T. F. Chung, P. Dutta, “A rapid magnetic particle driven micromixer,” Microfluidics and Nanofluidics, Vol. 4, pp. 375-389, 2008.
5. A. D. Stroock, S. K. W. Dertinger, A. Ajdari, I. Mezic, H. A. Stone and G. M. Whitesides, “Chaotic mixer for microchannels,“ Science, Vol. 295, pp. 647-651, 2002.
6. R. H. Liu, M. A. Stremler, K. V. Sharp, M. G. Olsen, J. G. Santiago, R. J. Adrian,H. Aref, and D. J. Beebe,“ Passive mixing in a three-dimensional serpentine microchannel,“ Journal of Microelectromechanical Systems , Vol. 9, pp. 190-197, 2000.
7. X. Fu, S. Liu, X. Ruan, H. Yang, “Research on staggered oriented ridges static micromixers,“ Sensors and Actuators B: Chemical, Vol. 114, pp. 618-624, 2006 .
8. Y. K. Suh, S. G. Heo, Y. G. Heo, H. S. Heo, S. Kang, “Numerical sand Experimental Study on a Channel Mixer with a Periodic Array of Cross Baffles,“ Journal of Mechanical Science and Technology , Vol. 21, pp. 549-555, 2007 .
9. B. He, B. J. Burke, X. Zhang, R. J. Zhang, and F. E. Regnier, “A picoliter-volume mixer for microfluidic analytical systems,” Analysis Chemistry, Vol. 73, pp. 1942-1947, 2001.
10. Wang, Hengzi, Iovenitti, Pio, Harvey, Erol, Masood, Syed, Deam, Rowan, “Mixing of liquids using obstacles in microchannels,” Proceedings of SPIE, Vol. 4590, pp. 204-212, 2001.
11. A.A.S. Bhagat, E.T.K. Peterson and I. Papautsky, “A passive planar micromixer with obstructions for mixing at low Reynolds numbers,” Journal of Micromechanics and Microengineering, Vol. 17, pp. 1017-1024, 2007.
12. 吳青峰(2004)，「渦流與注入流體位置對微型混合器效率之影響」，國立成功大學機械工程研究所碩士論文。
13. F. and S. Hardt, “Simulation of Helical Flows in Microchannels,” AIChE Journal, Vol. 50, pp. 771-778, 2004.
14. A. P. Sudarsan and V. M. Ugaz , “Multivortex micromixing,” Proceedings of the National Academy of Sciences of the United States of America, Vol. 103, pp. 7228-7233, 2006.
15. M. G. Lee, S. Choi ,and J.-K. Park, “Rapid multivortex mixing in an alternately formed contraction-expansion array microchannel,” Biomedical Microdevices, Vol. 12, pp. 1019-1026, 2010.
16. R.-T. Tsai, C.-Y. Wu, “An Efficient Micromixer Based on Multidirectional Vortices Dui to Baffles and Channel Curvature,” Biomicrofluidics, Vol. 5, pp. 1-13, 2011.
17. 陳正陞(2010)，「具檔板及迴流道之微流道中的流體混合」，國立成功大學機械工程研究所碩士論文。
18. S. A. Rani, B. Pitts and P. S. Stewart, “Rapid diffusion of fluorescent tracers into Staphylococcus epidermidis biofilms visualized by time lapse microscopy,” Antimicrobial Agents and Chemotherapy, Vol. 49, pp. 728-732, 2005.
19. L. H. Lu, K. S. Ryu and C. Liu, “A magnetic microstirrer and array for microfluidic mixing,” Journal of Microelectromechanical Systems, Vol. 11, pp. 462-469, 2002.
20. E.S. Oran and J.P. Boris (2001), Numerical Simulation of Reactive Flow, 2nd ed., New York: Cambridge University Press.