本研究主要是設計並利用微機電製程技術製作微流體晶片。本文分為兩部分：第一部份稱為微粒子流動操控晶片，第二部分稱為微流體聚焦晶片。微粒子流動操控晶片之工作原理為在一直微管道中鍍一對微電極，施以電場以產生一與壓力驅動流反向之電滲效應，由於此效應在微電極間壁面所產生之流體流動方向與壓力驅動流反向，為了滿足質量守恆，電極間管道壁面將產生迴流區，此迴流區域之大小將隨著電滲效應之增強而變大，而迴流區之增大將使得壓力驅動流體流經此電極間時受到擠壓而造成流體加速之效果，而通過此區域之微粒子之速度也將加速，本研究即利用各粒子加速先後之時間差在此區域進行微粒子之流動操控。實驗結果顯示，微粒子在單純的壓力驅動流中，兩顆微粒子彼此之間的距離很短的情形下，通過一具有迴流現象之區域時，因流體加速之關係，造成彼此間之距離將被增加，此局部區域微粒子分離效果對於光學偵測將有所助益。
第二部分微流體聚焦晶片之原理乃是以壓力作為驅動力，利用分層管道之結構達到微流體在微管道中的三維聚焦。利用微機電製程技術所製作之微流體晶片大多屬於平片結構，因此其對微管道中之流體及微粒可以有良好的二維（x-y平面）聚焦效應。但微粒於第三維方向（z方向）上，仍是自由分佈，因此造成流式細胞儀之偵測有些許誤差。本研究提出一種創新晶片，先利用上下兩層之側管道控制流體在z方向之聚焦，再由兩側邊鞘流做一平面之聚焦，以達成三維聚焦。實驗結果顯示，在低雷諾數下，微流體能藉由控制各邊鞘流之流速，使樣品流聚焦在管道中間位置。

In this study, we design and fabricate a novel microfluidic device for particle separation by MEMS technology. The mechanism is to utilized combined pressure-driven and electroosmotic force. In the straight channel, we used high-vacuum e-beam evaporator to deposit Pt/Cr electrode and apply an electric field opposite to the direction of the pressure-driven flow. Because of conservation of mass, the flow will form a recirculation zone between the two electrode. The size of this zone will be direct proportion to the strength of the electric field. Utilizing the recirculation zone to compress cross-section area and to accelerate particles passing through the recirculation zone. Because particles are accelerated at different time, particles will separate from each other. Experimental results show when the two particles pass through the recirculation zone, because they are accelerated at different time, their separation distance will increase.
The second part of this study, we use two layers channels by hydrodynamics forces to achieve 3-dimensional focusing chip. In microfluidic chip, it’s easy to achieve 2-dimensional focusing but appreciable errors could occur if the flow is randomly distributed in the z direction. In this study, a 3-D focusing microchip is demonstrated using the combination of two layers channel and hydrodynamics forces. Upper and lower sheath flows focus the sample flow in z direction and the others two sheath flows in the side channels focus the pre-focused sample flow in the x-y plane. Experimental results show sample flow will focus in center of the channel by controlling flow rate ratio of sheath flow under suitable Reynolds number.

[1] D.R. Reyes, D. Iossifidis, P.A. Auroux and A. Manz, “Micro Total Analysis Systems. 1. Introduction, Theory, and Technology”, Analytical Chemistry, Vol. 74, pp. 2623-2636, 2002
[2] C. H. Lin, G.. B. Lee, Y. H. Lin and G. L. Chang,“A Fast Prototyping Process for Fabrication of Microfluidic System on Soda-lime Glass”, Journal of Micromechanics and Microengineering, Vol. 11, pp. 726-732, 2001
[3] W. B. Russel, D. A. Saville and W. R. Schowalter, “Colloid Science: Principles and Applied Mathematics,” Cambridge University Press, Cambridge, 1989.
[4] R. J. Hunter, “Zeta Potential in Colloid Science：Principles and Applications, ” Academic Press, New York, 1981
[5] A. Tiselius, “A New Apparatus for Electrokinetic Analysis of Colloidal Mixtures, ” Transactions of the Faraday Society Articles, 33, 524, 1937
[6] R. F. Probstein, “Physicochemical hydrodynamics: an introduction,” 2nd ed., John Wiley and Sons, New York, 1994.
[7] S. Hjerten, “Free Zone Electrophoresis,” Chromatographic Reviews, 9, 122-219, 1967.
[8] J. W. Jorgenson and K. D. Lukacs, “Zone Electrophoresis in Open-tubular Glass Capillaries,” Analytical Chemistry, 53, 1298-1302, 1981.
[9] S. Otsuka, K. Terabe., A. Tsuchiya and T. Ando, “Electrokinetic Separation with Micellar Soulution and Open-tubular Capillaries,” Analytical Chemistry, 567, 111-113, 1984.
[10] S. Hjerten, J. L. Liao and K. J. Yao, “Theoretical and Experimental Study of High Performance Electrophoretic Mobilization of Isoelectric Focused Protein Zones,” Journal of Chromatography A, 387, 127-138, 1987.
[11] A. S. Cohen and B. L. Karger, “High-performance Sodium Dodecyl Sulfate Polyacrylamide Gel Capillary Electrophoresis of Peptides and Proteins,” Journal of Chromatography A, 397, 409-417, 1987.
[12] 田福助,吳溪煌, 電化學-理論與應用, 高立圖書有限公司。
[13] J. G. Collier, “Convective Boiling and Condensation”, McGraw-Hill Book Company.
[14] http://www.microchem.com/products/pdf/SU8_50-100.pdf
[15] J. C. McDonald, D. C. Duffy, J. R. Anderson, D. T. Chiu, H. Wu, O. J. A. Schueller and G. M. Whitesides, “Fabrication of Microfluidic Systems in Poly(dimethylsiloxane) , Electrophoresis, Vol. 21, pp. 27-40, 2000”
[16] R. W. Applegate Jr, J. Squier, T. Vestad, J. Oakey and D. W. M. Marr, “Optical Trapping, Manipulation, and Sorting of Cells and Colloidsin Microfluidic Systems with Diode Laser Bars ” , Optics Express, Vol. 12, pp. 4390-4398, 2004
[17] M. M. Wang, E. Tu, D. E. Raymond, J. M. Yang, H. Zhang, N. Hagen, B. Dees, E. M. Mercer, A. H. Forster, I. Kariv, P. J. Marchand and W. F. Butler, “Microfluidic Sorting of Mammalian Cells by Optical Force Switching”, Nature Biotechnology, Vol. 23, pp.83-87, 2005
[18] Z. H. Fan and D. J. Harrison, “Micromachining of Capillary Electrophoresis Injectors and Separators on Glass Chips and Evaluation of Flow at Capillary Intersections,” Analytical Chemistry, 66, 177-184, 1994.
[19] A. Y. Fu, C. Spence, A. Scherer, F. H. Arnold and S. R. Quake, “A Microfabricated Fluorescence-activated Cell Sorter”, Nature Biotechnology ,Vol. 17, pp.1109-1111, 1999
[20] M. Yamada, M. Nakashima and M. Seki, “Pinched Flow Fractionation: Continuous Size Separation of Particles Utilizing a Laminar Flow Profile in a Pinched Microchannel”, Analytical Chemistry , Vol. 76, pp. 5465-5471 , 2004
[21] X. Xuan, B. Xu and D. Li, “Accelerated Particle Electrophoretic Motion and Separation in Converging-Diverging Microchannels”, Analytical Chemistry, Vol. 77, pp. 4323-4328, 2005
[22] X. Xuan, B. Xu and D. Li, “Particle Motions in Low-Reynolds Number Pressure-driven Flows through Converging–diverging Microchannels”, Journal of Micromechanics and Microengineering, Vol. 16, pp. 62-69, 2006
[23] M. Yamada and M. Seki, “Hydrodynamic Filtration for On-chip Particle Concentration and Classification Utilizing Microfluidics”, Lab on a Chip, Vol. 5, pp. 1233-1239, 2005
[24] M. Yamada and M. Seki, “Microfluidic Particle Sorter Employing Flow Splitting and Recombining”, Analytical Chemistry, Vol. 78, pp. 1357-1362,2006
[25] K. H. Kang, Y. Kang, X. Xuan and D. Li, “Continuous Separation of Microparticies by Size with Direct Current-dielectrophoresis”, Electrophoresis, Vol. 27, pp. 694-702, 2006
[26] R. G. H. Lammertink, S. Schlautmann, G. A. J. Besselink and R. B. M. Schasfoort, ,“Recirculation of Nanoliter Volumes within Microfluidic Channels”, Analytical Chemistry, Vol. 76, pp. 3018-3022, 2004
[27] G.. L. Lettieri, A. Dodge, G. Boer, N. F. de Rooij and E. Verpoorte, “A Novel Microfluidic Concept for Bioanalysis Using Freely Moving Beads Trapped in Recirculating Flows”, Lab on a Chip, Vol.3, pp. 34–39, 2003
[28] J. P. Freyer, M. E. Wilder, P. L. Schor and J. M. R. Coulter, “A Simple Electronic Volume Cell Sorter for Clonogenicity Assays,” Cytometry, 10, 273-281, 1989.
[29] U. D. Larsen, G. Blankenstein and J. Brangebjerg, “A Novel Design in Chemical and Biochemical Liquid Analysis System,” Proc. 2nd Int. Symp. μTAS96, 113-115, 1996.
[30] D. P. Schrum, C.T. Culbertson, S.T. Jacobson and J. M. Ramsey, “Microchip Flow Cytometry Using Electorokinetic Focusing,” Analytical Chemistry, 71, 4173-4177, 1999.
[31] G. B. Lee, C. I. Hung, B. J. Ke, G. R. Huang and B. H. Hwei, “Micromachined Pre-focused 1×N Flow Switches for Continuous Sample Injection,” Journal of Micromechanics and Microengineering, 11, 567-573, 2001.
[32] G. B. Lee, B. H. Hwei and G. R. Huang, “Micromachined Pre-focused M×N Flow Switch for Continuous Sample Injection,” Journal of Micromechanics and Microengineering, 11, 654-661, 2001.
[33] G. B. Lee, C. H. Lin and G. L. Chang, “Micro Flow Cytometers with Buried SU-8/SOG Optical Waveguides,” Sensors and Actuators A, 103, 165-170, 2002.
[34] C. H. Lin, G. B. Lee, L. M. Fu and B. H. Hwey, “Vertical Focusing Device Utilizing Dielectrophoretic Force and Its Application on Microflow Cytometer”, Jouranl of Microelectromechanical Systems, Vol. 13, pp. 923-932, 2004
[35] N. Sundararajan, M. S. Pio, L. P. Lee and A. A. Berlin, “Three-Dimensional Hydrodynamic Focusing in Polydimethylsiloxane (PDMS) Microchannels”, Jouranl of Microelectromechanical Systems, Vol. 13, pp. 559-567, 2004
[36] C. Yu, J. Vykoukal, D. M. Vykoukal, J. A. Schwartz, L. Shi and P. R. C. Gascoyne, “A Three-Dimensional Dielectrophoretic Particle Focusing Channel for Microcytometry Applications”, Jouranl of Microelectromechanical Systems, Vol. 14, pp. 480-487, 2005
[37] C. Simonnet and A. Groisman, “Two-Dimensional Hydrodynamic Focusing in A Simple Microfluidic Device”, Applied Physics Letters, Vol. 87, 2005