近來，利用微機電技術製作的生醫晶片(Biochip)以及檢測型微流體系統晶片，在臨床診斷、醫療檢測上愈發扮演重要的角色。然而，微流體系統晶片的製作除了生化知識外，搭配微機電製造技術，將可大幅提升其性能，強化自動化功能，減少人為操作檢測造成的污染及誤差。此外，如何把微量流體快速而連續注入微流體生醫晶片是一項非常重要的課題，本論文中，我們設計且研製兩個重要的元件——微流體切換器(micro fluidic switches)以及微幫浦(micropumps)，將其發展於微流體系統晶片上以達到輸送以及分配的功能。
由文獻回顧中，我們可知微流體切換器的發展以及應用，受限於需外加多組大型幫浦來做為動力來源或需要複雜的可動件設計，且其切換機制會容易造成溢漏情形，因此，微流體切換器的設計更顯得重要，其主要應用於在微流體晶片上，除具有集中微量樣品的功用外，還可控制樣品的流向，可將樣品集中分別導入不同的出口導管以進行後續檢測之功能。本文將介紹一種新型熱氣泡驅動式1×N微流體切換器，藉由疏水區塊的排列設計以及對於氣泡的體積大小和產生的次數進行時序控制，以達到微流體切換的機制，且當流體於切換過程中，鐵弗龍區塊(Teflon areas)的疏水特性不會造成流體溢漏情形。經由我們的實驗結果，顯示此一裝置可有效且精準的將流體由入口切換至指定的出口。且藉由邏輯推導出所最佳的時序控制信號，可藉由電腦程式語言的撰寫，交由數位控制晶片來產生所需的連續控制信號，將複雜的流體切換簡化，將有助於1×N微流體切換器應用於實驗室晶片上。
另外，微幫浦的設計更是微流體晶片上不可或缺的一環，它是輸送流體的動力來源，主要具有輸送微量樣品的功用以及控制樣品的流向，其發展已有多年之久，目前，為了應用於生醫晶片以及各種檢測型微流體系統晶片上，正朝向一種能達到低耗能、低驅動電壓以及室温操作之微幫浦來發展。而電解氣泡方式是最為符合此三要件之驅動器，但由文獻回顧可知，電解氣泡驅動式微幫浦的發展以及應用受限於需要複雜且多組的電路設計及控制、複雜製程的可動件設計以及限制流體儲存必需為密閉空間。本文將介紹一種新型電解氣泡驅動式微流體幫浦，藉由疏水微柱子的排列設計以形成一個特殊之粗糙梯度表面(roughness gradient surface)來創造一種新型的幫浦機制，再加上對氣泡的產生進行時序控制，以達到連續輸送微流體的機制。經由我們的實驗結果，顯示此一裝置不但製程簡單且可有效的輸送流體前進。且藉由在不同施加電壓下，量測氣泡膨脹時間以及氣泡排除時間以計算所需的連續控制信號操作頻率，再經由電腦程式語言的撰寫以及數位控制晶片來產生，以利於精確控制流體流速。
本論文中，我們成功的研製以及發展新型微流體切換器以及電解氣泡驅動式微幫浦，它們的理論推導、設計概念、微製程設計、操作原理以及性能量測全都詳細敍述於本文各章節中。以長遠目標來說，我們將以電解氣泡驅動方式整合微流體切換器以及微幫浦於微流體系統晶片上，以達到將微量流體或樣本輸送以及分配的功能，進而加速生醫晶片以及檢測型微流體系統晶片的發展。

A microfluidic system, which integrates sample pretreatment, transportation, reaction, separation and detection on a small chip, can be realized by combining several microfluidic subsystems with specific functions. For the microfluidic systems, the precise handling of small volumes of test reagents is essential. Practical microfluidic applications require an efficient way for both microscale pumping and flow control. Thus, continuous liquid handling is critical to the microfluidic system. For the handling of continuous liquid, this research focuses on the development of microfluidic system chip which is capable of pumping and guiding continuous liquid inside multi-ported microchannels. This thesis is therefore aimed at investigating two microfluidic subsystems — the 1*N micro fluidic switch and the low-power consumption micropump.
In the micro fluidic switch design, we introduce a robust approach by utilizing the hydrophobic/hydrophilic properties that generate the capillary force and the barrier pressure to achieve the switching function. The distributed hydrophobic-patch design and the programmable time-sequence bubble actuation are taken advantage for the function of microfluidic switch. The design and implementation of a novel thermal-bubble-actuated 1×N micro flow switch without the need of external macro pumps is presented. The switch mechanism among different microchannels is dominated by controlling the format and the timing of power input that generates the actuation thermal-bubbles. The experimental results successfully demonstrate the switch function in a chip to guide the sample liquid into desired outlet ports via programmable time-sequence control pulses.
In the micropump design, a novel actuation mechanism utilizing the roughness gradient surface to achieve the net pumping flow is investigated. This micropump is implemented by taking advantage of the electrolysis actuation, the surface tension effect and the periodic generation of electrolysis-bubble. This proposed micropump design not only achieves a net pumping flow but also resolves the main problem that exists in most electrolytic bubble actuators on the issue of degassing the insoluble gases out of microchannels. This micropump driven by a simple circuit control without mechanical moving parts is suitable for the development of low power-consumption and compact micropumps. Experimental results demonstrate the pumping function of our micropump to continuously push liquid forward based on our roughness gradient design and the periodic electrolytic-bubble generation in the microchannel. Furthermore, experimental results also show that the liquid displacement and the pumping rate could be easily and accurately controlled by adjusting the amplitude and the frequency of the applied voltage.
In this study, our 1*N micro fluidic switches and the low-power consumption micropumps have been successfully demonstrated. The theoretical analysis, design, micromachining process, operating principles, and characterization are all described in this thesis. The long-term goal of this work is to integrate the micro fluidic switches and the micropumps into a closed-loop microfluidic system for specific flow guiding, specific flow injection, and precise liquid volume control.

REFERENCES
[1] A. Manz, N. Graber, H. M. Widmer, “Micro total analytical system,” Sensors and Actuators B, pp. 244-248, 1990.
[2] M. Kohl, D. Dittmann, E. Quandt and B. Winzek, “Thin film shape memory microvalves with adjustable operation temperature,” Sensors and Actuators A, vol. 83, pp. 214-219, 2000.
[3] Shifeng Li and Shaochen Chen, “Analytical analysis of a circular PZT actuator for valveless micropumps, ” Sensors and Actuators A, vol. 104, pp. 151-161, 2003.
[4] Hsin-Yu Wu and Cheng-Hsien Liu, “A Novel Micromixer,” Sensors and Actuators A, vol. 118, pp. 107-115, 2005.
[5] D. Baechi, R. Buser and J. Dual, “A high density microchannel network with integrated valves and photodiodes,” Sensors and Actuators A, vol.95, pp.77-83, 2002.
[6] G. Bedö, H. Fannasch and R. Müller, “A silicon flow sensor for gases and liquids using AC measurements,” Sensors and Actuators A, vol. 85, pp.124-132, 2000.
[7] D. Erickson and D. Li, “Integrated microfluidic devices,” Analytica Chimica Acta, pp. 11-26, 2004.
[8] M. Burns, B. Johnson, S. Brahmasandra, K. Handique, J. Webster, M. Krishnan, T. Sammarco, P. Man, D. Jones, D. Heldsinger, C. Mastrangelo, and D. Burke, “An integrated nanoliter DNA analysis device,” Science, vol. 282, pp. 484–487, 1998.
[9] D. Figeys and D. Pinto, “Lab-on-a-chip: A revolution in biological and medical sciences,” Anal. Chem., vol. 72, pp. 330–335, 2000.
[10] E. Vespoorte, “Microfluidic chips for clinical and forensic analysis,” Electrophoresis, vol. 23, pp. 677–712, 2002.
[11] P. Bergstrom, K. Wise, S. Patel, and J. Schwank, “A micromachined surface work-function gas sensor for low-pressure oxygen detection,” Sens. Actuators B, vol. 42, no. 3, pp. 195–204, Aug. 1997.
[12] W. Schomburg, J. Fahrenberg, D. Maas, and R. Rapp, “Active valves and pumps for microfluidcs,” J. Micromech. Microeng., vol. 3, pp. 216–218, 1993.
[13] D. Sadler, K. Oh, C. Ahn, S. Bhansali, and H. T. Henderson, “A new magnetically actuated microvalve for liquid and gas control applications,” in Proc. Transducers’99, pp. 1812–1815.
[14] M. Koch, N. Harris, A. Evans, N. White, and A. Brunnschweiler, “A novel micropump design with thick-film piezoelectric actuation,” Measure. Sci. Technol., vol. 8, pp. 49–57, 1997.
[15] S. Zeng, C. Chen, J. Mikkelsen, and J. Santiago, “Fabrication and characterization of electroosmotic micropumps,” Sens. Actuators, vol. B 79, pp. 107–114, 2001.
[16] N. Jeon, D. Chiu, C. Wargo, H. Wu, I. Choi, J. Anderson, and G. Whitesides, “Design and fabrication of integrated passive valves and pumps for flexible polymer 3-dimensional microfluidic systems,” Biomed. Microdev., vol. 4, no. 2, pp. 117–121, 2002.
[17] K. Handique, B. Gogoi, D. Burke, and C. Mastrangelo, “Microfluidic flow control using selective hydrophobic patterning,” in Proc. Micromachined Devices and Components, vol. 3224, 1999, pp. 210–220.
[18] D. Beebe, R. Adrian, M. Olsen, M. Stremler, H. Aref, and B. Jo, “Passive mixing in microchannels: Fabrication and flow experiments,” Mecanique Ind., vol. 2, no. 4, pp. 343–348, July–Aug. 2001.
[19] S. Bohm, K. Greiner, S. Schlautmann, S. Vries, and A. Berg, “A rapid-vortex micromixer for studying high-speed chemical reactions,” presented at the UTAS 01, Monterey, CA, 2001.
[20] J. Brody and P. Yager, “Diffusion-based extraction in a microfabricated device,” Sens. Actuators A, vol. 54, no. 1–3, pp. 704–708, 1996.
[21] B. Weigl and P. Yager, “Microfluidic diffusion-based separation and detection,” Science, vol. 283, pp. 346–347, 1999.
[22] T. Desai, D. Hansford, and M. Ferrrari, “Micromachined interfaces: New approaches in cell immunoisolation and bimolecular separation,” Biomol. Eng., vol. 17, no. 1, pp. 23–36, 2000.
[23] F. Martin and C. Grove, “Microfabricated drug delivery systems: Concepts to improve clinical benefit,” Biomed. Microdev., vol. 3, no. 2, pp. 97–108, 2001.
[24] Y. Su, L. Lin, and A. Pisano, “Water-powered, osmotic microactuator,” in Proc. IEEE MEMS 2001, pp. 393–396.
[25] G. Walker and D. Beebe, “A passive pumping method for microfluidic devices,” Lab. Chip, vol. 2, pp. 131–134, 2002.
[26] S. Böhm, B. Timmer, W. Olthuis, and P. Bergveld, “A closed-loop controlled electrochemically actuated micro-dosing system,” J. Micromech. Microeng. , vol. 10, pp. 498-504, 2000.
[27] S. W. Lee, W. Y. Sim and S. S. Yang, “Fabrication and in vitro test of a microsyringe,” Sensors and Actuators A, vol. 83, pp.17-23, 2000.
[28] H. Suzuki, R. Yoneyama, “A reversible electrochemical nanosyringe pump and some considerations to realize low-power consumption,” Sensors and Actuators B, vol.86, pp.242-250, 2002.
[29] D. J. Laser and J. G. Santiago, “A Review of Micropumps”, J. Micromech. Microeng., vol. 14, no. 6, pp. R35-R64, 2004.
[30] Kwang W Oh and Chong H Ahn, "A review of microvalves," J. Micromech. Microeng., vol. 16, no 5 pp. R13-R39, 2006.
[31] T. Thorsen, S. J. Maerkl, S. R. Quake, “Microfluidic large-scale integration,” Science, 298, pp.580-584, 2002.
[32] C. Doring, T. Grauer, J. Marek, M. S. Mettner, H. P. Trah, M. Willmann, “Micromachined Thermoelectrically driven cantilever structures for fluid jet deflection”, IEEE Micro Electro Mechanical Systems Workshop (MEM’92), pp. 12-18, 1992.
[33] G. Blankenstein, U. D. Larsen, “Modular concept of a laboratory on a chip for chemical and biochemical analysis”, Biosensors &. Bioelectronics, vol.13, no. 3-4, pp. 427-438, 1998.
[34] U. Gebhard, H. Hein, E. Just, P. Ruther, ”Combination of a fluidic micro-oscillator and micro-actuator in LIGA-technique for medical application”, Solid-State Sensors and Actuators (Transducers’97), pp. 761-764, 1997.
[35] G. B. Lee, C. I Hung, B. J. Ke, G. R. Huang, B. H. Hwei, “Micromachined pre-focused 1×N flow switches for continuous sample injection”, J. of Micromechanics and Micro engineering, vol. 11, pp. 567-573, 2001.
[36] G. B. Lee, B. H. Hwei, G. R. Huang, “Micromachined pre-focused M×N flow switches for continuous multi-sample injection”, J. of Micromechanics and Microengineering, vol. 11, pp. 654-661, 2001.
[37] A. V. Lemoff, A. P. Lee, “An AC Magnetohydrodynamic Microfluidic Switch for Micro Total Analysis Systems”, Biomedical Microdevices, vol. 5, no. 1, pp. 55-60, 2003.
[38] T. Okamoto, T. Suzuki, N. Yamamoto, “Microarrary fabrication with covalent attachment of DNA using bubble jet technology,” Nature Biotechnology, pp. 438-441, 2000.
[39] R. B. Maxwell, A. L. Gerhardt, M. A. Schmidt, and M. Toner,“ A Microbubble Powered Bioparticle Actuator,” J. of Microelectromechanical Systems, vol. 12, no. 5, pp.630-640, 2003.
[40] H. Andersson, W. van der Wijngaart, P. Nilsson, P. Enoksson, and G. A. Stemme, “A Valve-less Diffuser Micropump for Microfluidic Analytical Systems,” Sensors and Actuators B, vol. 72, pp. 259-265, 2001.
[41] L. Cao, S. Mantell, and D. Polla, “Design and simulation of an implantable medical drug delivery system using microelectromechanical systems technology,” Sensors and Actuators A, vol. 94, pp. 117-125, 2001.
[42] M. Koch, N. Harris, A. G. R. Evans, N. M. White, and A. Brunnschweiler, “A Novel Micromachined Pump Based on Thick-Film Piezoelectric Actuation,” Sensors and Actuators A, vol. 70, pp. 98-103, 1998.
[43] S. Santra, P. Holloway, and C. D. Batich, “Fabrication and testing of a magnetically actuated micropump,” Sensors and Actuators B, vol. 87, pp. 358-364, 2002.
[44] O. C. Jeong and S. S. Yang, “Fabrication and test of a. thermopneumatic micropump with a corrugated P. +. Diaphargm,” Sensors and Actuators A, vol. 83, pp. 249-255, 2000.
[45] O. Francais and I. Dufour, “Dynamic simulation of an electrostatic micropump with pull-in and hysteresis phenomena,” Sensors and Actuators A, vol. 70, pp. 56-60, 1998.
[46] A. D. Stroock, M. Weck, D. T. Chiu, W. T. S. Huck, P. J. A. Kenis, R. F. Ismagilov, and G. M. Whitesides, “Patterning electro-osmotic flow with patterned surface charge,” Phys. Rev. Lett. , vol. 84, pp. 3314-3317, 2000.
[47] A. Manz, C. S. Effenhauser, N. Burggraf, D. J. Harrison, K. Seiler, and K. Fluri, “Electroosmotic pumping and. electrophoretic separations for miniaturized chemical analysis systems,” J. Micromech. Microeng., vol. 4, pp. 257-265, 1994.
[48] A. Richter, A. Plettner, K. A. Hofmann, and H. Sandmaier, “A micromachined electrohydrodynamic (EHD) pump,” Sensors and Actuators A, vol. 29, no. 2, pp. 159-168, 1991.
[49] T. K. Jun and C. J. Kim, "Valveless Pumping using Traversing Vapor Bubbles in Microchannels,” J. Applied Physics, vol. 83, pp. 5658-5664, 1998.
[50] J. H. Tsai and L. Lin, “A Thermal-Bubble-Actuated Micronozzle-Diffuser Pump”, J. of Microelectromechanical Systems, vol. 11, pp.665-671, 2002.
[51] X. Geng, H. Yuan, H. N. Oguz and A. Prosperetti, “Bubble-based micropump for electrically conducting liquids,” J. Micromech. Microeng., vol. 11, pp. 270-276, 2001.
[52] Z. Yin and A. Prosperetti, “A microfluidic ‘blinking bubble’ pump,” J. Micromech. Microeng., vol.15, pp. 643-651, 2005.
[53] J. H. Tsai, L. W. Lin, “Transient Thermal Bubble Formation on Polysilicon Micro-Resisters,” J. of Heat Transfer, vol. 124, no. 2, pp. 375-382, 2002.
[54] P. F. Man, C. H. Mastrangelo, M. A. Burns, and D. T. Burke, “Microfabricated Capillarity-Driven Stop Valve and Sample Injector,” IEEE Micro Electro Mechanical Systems Workshop (MEM’98), pp. 45-50, 1998.
[55] A. A. Deshmukh, D. Liepmann, and A. P. Pisano, ”Characterization of. a micro-mixing, pumping, and valving system,” Solid-State Sensors and Actuators (Transducers’01) , Munich, Germany, pp. 950-953, 2001.
[56] D. A. Ateya, A. A. Shah, and S. Z. Hua, “An electrolytically actuated micropump,” Rev. Sci. Instrum. , vol. 75, pp. 915-920, 2004.
[57] D. S. Meng and C. J. Kim, “Micropumping by Directional Growth and Hydrophobic Venting of Bubbles,” IEEE Micro Electro Mechanical Systems Workshop (MEM’05), pp. 423-426, 2005.
[58] M. M. Maharbiz, W. J. Holtz, S. Sharifzadeh, J. D. Keasling, and R. T. Howe, “A Microfabricated Electrochemical Oxygen Generator for High-Density Cell Culture Arrays,” J. of Microelectromechanical Systems, vol. 12, pp.590-599, 2003.
[59] K.-S. Yun, I. J. Cho, J. U. Bu, C. J. Kim, and E. Yoon, “A surface-tension driven micropump for low-voltage and low-power operations,” J. Microelectromech. Syst., vol. 11, no. 5, pp. 454–461, 2002.
[60] A. Shastry, M. Case, and K. F. Böhringer, “Engineering Surface Texture to Manipulate Droplets in Microfluidic Systems,” IEEE Micro Electro Mechanical Systems Workshop (MEM’05), pp. 694 -697, 2005.
[61] J. Lee, B. He, and N. A Patankar, “A roughness-based wettability switching membrane device for hydrophobic surfaces,” J. Micromech. Microeng., vol. 15, pp. 591-600, 2005.
[62] P. F. Man, C. H. Mastrangelo, M. A. Burns, D. T. Burke, “Microfabricated Plastic Capillary Systems With Photo-Definable Hydrophilic and Hydrophobic Regions”, Solid-State Sensors and Actuators (Transducers’99), pp. 738-741, 1999.
[63] A. Asai, “Three-dimensional calculation of bubble growth and drop ejection in a bubble jet printer”, J. Fluids Eng., vol. 114, pp. 638-641, 1992.
[64] Y. Iidea, K. Okuyama, K. Sakurai, “Boiling nucleation on a very small film heater subjected to extremely rapid heating”, Int. J. Heat Mass Transfer, vol. 37, no. 17, pp. 2771-2780, 1994.
[65] R. R. Allen, J. D. Meyer, W. R. Knight, “Thermodynamics and hydrodynamics of thermal ink jets”, Hewlett-Packard J., vol. 36, no. 5, pp. 21-27, 1985.
[66] A. Asai, “Bubble dynamics in boiling under high heat flux pulse heating”, J. Heat Transfer, vol. 113, pp. 973-979, 1991.
[67] P. H. Chen, W. C. Chen, S. H. Chang, “Bubble growth and ink ejection process of a thermal ink jet printerhead”, Int. J. Mech. Sci., vol. 39, no. 6, pp. 683-695, 1997.
[68] P. Deng, Y. K. Lee, P. Cheng, “The growth and collapse of a micro-bubble under pulse heating”, J. of Heat and Mass Transfer, vol. 46, no. 21, pp. 4041-4050, 2003.
[69] S. V. Stralen, R. Cole, Boiling Phenomena, Hemisphere Pub. Corp., Bristol, PA, vol. 1, pp. 454-456, 1979.
[70] J. H. Tsai, L. W. Lin, “Transient Thermal Bubble Formation on Polysilicon Micro-Resisters” , J. of Heat Transfer, vol. 124, no. 2, pp. 375-382, 2002.
[71] Z. Zhao, S. Glod, D. Poulikakos,” Pressure and power generation during explosive vaporization on a thin-film microheater”, J. of Heat and Mass Transfer, vol. 43, pp. 281-296, 2000.
[72] J. H. Tsai, L. W. Lin, “Transient Thermal Bubble Formation on Polysilicon Micro-Resisters”, J. of Heat Transfer, vol. 124, no. 2, pp. 375-382, 2002.
[73] Shibuichi S, Onda T, Satoh N and Tsujii K, “Super water-repellent surfaces resulting from fractal structure,” J. Phys. Chem., vol. 100, pp. 19512-19517, 1996.
[74] J. Bico, C. Marzolin, and D. Quéré, “Pearl drops,” Europhysics Letters, vol. 47, no. 2, pp. 220-226, 1999.
[75] R. N. Wenzel, “Surface Roughness and Contact Angle,” J. of Physical Colloid Chemistry, vol. 53, no. 9, pp. 1466-1467, 1949.
[76] A. B. D. Cassie and S. Baxter, “Wettability of Porous surfaces,” Transactions of the Faraday Society, vol. 40, pp. 546-551, 1944.
[77] A. Shastry, M. J. Case, K. F. Böhringer, “Directing droplets using micro-structured surfaces,” Langmuir, vol. 22, pp. 6161-6167, 2006
[78] N. J. Shirtcliffe, S. Aqil, C. Evans, G. McHale, M. I. Newton, C. C. Perry, and P. Roach, ”The use of high aspect ratio photoresist (SU-8) for super-hydrophobic pattern prototyping,” J. Micromech. Microeng., vol. 14, pp.1384-1389, 2004.
[79] C. G. Cameron and M. S. Freund, ”Reversible and Efficient Materials-based Actuation by Electrolytic Phase Transformation,” Chemical Engineering & Technology, vol.26, pp. 1007-1011, 2003.
[80] S. Böhm, W. Olthuis, and P. Bergveld, “An integrated micromachined electrochemical pump and dosing system,” J. Biomed. Microdev., vol. 1, pp. 121-130, 1999.
[81] J. Lee, H. Moon, J. Fowler, T. Schoellhammer and C.-J. Kim, “Electrowetting and electrowetting-on-dielectric for microscale liquid handling,” Sensors and Actuators A, vol. 95, pp. 259-268, 2002.
[82] L. Gao and T. J. McCarthy, “Artificial Lotus Leaf,” Langmuir, vol. 22, pp. 5998 - 6000, 2006.
[83] A. Shastry, A. Epilepsia, M. J. Case, S. Abbasi, and K. F. Böhringer, “Bounds on contact angle hysteresis of textured super-hydrophobic surfaces,” Proc. MicroTAS, pp. 122-124, 2006
[84] D.-S. Meng, T. Cubaud, C.-M. Ho, and C.-J. Kim, “A Membrane breather for micro fuel cell with high concentration methanol,” Proc. Hilton Head 2004: A Solid State Sensor, Actuator and Microsystems Workshop, pp. 141-144, 2004.
[85] J. P. Hoare, “Some effects of alternating current polarization on the surface of noble metal electrodes,” Electrochemica Acta, vol. 9, no. 5, pp. 599-605, 1964.
[86] T. K. Jun and C.-J. Kim, "Valveless Pumping using Traversing Vapor Bubbles in Microchannels,” J. Applied Physics, vol. 83, pp. 5658-5664, 1998.
[87] S. Bohm, W. Olthuis and P. Bergveld, “A Bi-Directional Electrochemically Driven Micro Liquid Dosing System with Integrated Sensor/Actuator Electrodes,” IEEE Micro Electro Mechanical Systems Workshop (MEM’00), pp. 92–95, 2000.
[88] C. Su and L. W. Lin, “Geometry and Surface Assisted Flow Discretization,” Solid-State Sensors and Actuators (Transducers’03), pp. 1812-1815, 2003.
[89] H. Suzuki, R. Yoneyama, “Integrated microfluidic system with electrochemically actuated on-chip pumps and valves,” Sensors and Actuators B, vol. 96, pp. 38-45, 2003.