本研究利用工業上光碟製程所製作之微流道平台，以田口方法對微乳化球形成進行最佳化分析，並應用於均一粒徑褐藻酸鈣微膠囊之生成。研究策略為結合微射出成形製程製作十字型微流道及應用該流道結構之鞘流原理來形成均一粒徑微乳化球，並將1.5% (w/v) 褐藻酸鈉微乳化球，滴入20% (w/v)氯化鈣溶液中，有效率地製備褐藻酸鈣微膠囊。本研究以計算流體力學軟體來模擬微流道中流體及乳化球運動現象，並經實驗證明藉由操控連續相/分離相(邊鞘流/樣品流)的流量比值，可輕易地將褐藻酸鈉微乳化球之粒徑控制於20 ~ 70 µm間，其變化量低於10%，結果顯示固定分離相流量，微乳化球粒徑會隨著連續相增加而減小。此外，利用田口方法探討流量比值以外其他控制因子，對微乳化球粒徑之影響，當最佳化參數組合為分離相流量1 μL/min、連續相/分離相流量比值10、分離相黏滯係數27 cP及連續相界面活性劑span 80濃度2% (v/v)時，系統有最小粒徑19.67 μm之微乳化球產生，較原始設計產出尺寸減少23.86%。本微流道平台可生成均一粒徑微乳化球，並具有粒徑可操控性以及製程簡易、成本低、產能高等優點。

This study describes the optimal formation of microemulsions with Taguchi method and the generation of monodisperse calcium alginate (Ca-alginate) microcapsules on a microfluidic platform using the commercial optical disc process. Our strategy is based on combining the injection molding process for cross-junction microchannel with the sheath focusing effect to form uniform water-in-oil (w/o) emulsions. These emulsions, consisting of 1.5% (w/v) sodium alginate (Na-alginate), are then dripped into a solution containing 20% (w/v) calcium chloride (CaCl2) creating Ca-alginate microparticles in an efficient manner. This study utilizes Computational Fluid Dynamic (CFD) software to simulate the motion of fluids and emulsions in microfluidic channel. We demonstrate that the size of Ca-alginate microparticles can be controlled from 20 µm to 70 µm in diameter with a variation of less than 10%, simply by altering the relative dispersed/dispersed (sheath/sample) phase flow rate ratio. Experimental data show that for a given fixed dispersed phase flow, the emulsion size decreases as the average flow rate of the continuous phase flow increases. We apply Taguchi method to investigate the influence of other controlled factors on the size of microemulsions except the flow rate ratio, and find that the optimal parameter dispersed phase flow rate in 1 μL/min, flow rate ratio in 10 between continuous/dispersed phases, viscosity of dispersed phase in 27 cP, and span 80 concentration in 2% (v/v) have the smallest emulsion size 19.67 μm lower 23.86% than original design. The proposed microfluidic platform is capable of generating relatively uniform emulsions and has the advantages of active control of the emulsion diameter, a simple and low cost process, and a high throughput.

1. H.G.B. de Jong and H.R. Kruyt, "Coacervation (partial miscibility in colloid systems)," Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, 32, 849-856, 1929.
2. D.E. Wurster, "Air-suspension technique of coating drug particles; a preliminary report," Journal of the American Pharmaceutical Association, 48, 451-454, 1959.
3. S.C. Khanna and P. Speiser, "Epoxy resin beads as a pharmaceutical dosage form. I: Method of preparation," Journal of Pharmaceutical Sciences, 58, 1114-1117, 1969.
4. R. Arshady, "Microspheres and microcapsules: A survey of manufacturing techniques. Part 1: Suspension cross-linking," Polymer Engineering and Science, 29, 1746-1758, 1989.
5. R. Arshady, "Microspheres and microcapsules: A survey of manufacturing techniques. Part 2: Coacervation," Polymer Engineering and Science, 30, 905-914, 1990.
6. R. Arshady, "Microspheres and microcapsules: A survey of manufacturing techniques. Part 3: Solvent evaporation," Polymer Engineering and Science, 30, 915-924, 1990.
7. S. Watnasirichaikul, T. Rades, I.G. Tucker, and N.M. Davies, "Effects of formulation variables on characteristics of poly (ethylcyanoacrylate) nanocapsules prepared from w/o microemulsions," International Journal of Pharmaceutics, 235, 237-246, 2002.
8. A. Hoffman, "Pharmacodynamic aspects of sustained release preparations," Advanced Drug Delivery Reviews, 33, 185-199, 1998.
9. G. Levy, "Bioavailability, clinical effectiveness, and public interest," Pharmacology, 8, 33-43, 1972.
10. P.S. Banerjee and J.R. Robinson, "Novel drug delivery systems - an overview of their impact on clinical pharmacokinetic studies," Clinical Pharmacokinetics, 20, 1-14, 1991.
11. G. Castaneda-Hernandez, G. Caille, and P. Dusouich, "Influence of drug formulation on drug concentration-effect relationships," Clinical Pharmacokinetics, 26, 135-143, 1994.
12. A. Martinsen, G. Skjakbraek, and O. Smidsrod, "Alginate as immobilization material: I. Correlation between chemical and physical-properties of alginate gel beads," Biotechnology and Bioengineering, 33, 79-89, 1989.
13. P. DeVos, B. DeHaan, and R. VanSchilfgaarde, "Effect of the alginate composition on the biocompatibility of alginate-polylysine microcapsules," Biomaterials, 18, 273-278, 1997.
14. J.H. Cui, J.S. Goh, P.H. Kim, S.H. Choi, and B.J. Lee, "Survival and stability of bifidobacteria loaded in alginate poly-l-lysine microparticles," International Journal of Pharmaceutics, 210, 51-59, 2000.
15. W. Sabra, A.P. Zeng, and W.D. Deckwer, "Bacterial alginate: Physiology, product quality and process aspects," Applied Microbiology and Biotechnology, 56, 315-325, 2001.
16. N. Gerbsch and R. Buchholz, "New processes and actual trends in biotechnology," Fems Microbiology Reviews, 16, 259-269, 1995.
17. X.D. Liu, W.Y. Yu, Y. Zhang, W.M. Xue, W.T. Tu, Y. Xiong, X.J. Ma, Y. Chen, and Q. Yuan, "Characterization of structure and diffusion behaviour of Ca-alginate beads prepared with external or internal calcium sources," Journal of Microencapsulation, 19, 775-782, 2002.
18. A. Kikuchi, M. Kawabuchi, M. Sugihara, Y. Sakurai, and T. Okano, "Pulsed dextran release from calcium-alginate gel beads," Journal of Controlled Release, 47, 21-29, 1997.
19. T. Ostberg, E.M. Lund, and C. Graffner, "Calcium alginate matrices for oral multiple-unit administration: IV. Release characteristics in different media," International Journal of Pharmaceutics, 112, 241-248, 1994.
20. G. Fundueanu, C. Nastruzzi, A. Carpov, J. Desbrieres, and M. Rinaudo, "Physico-chemical characterization of Ca-alginate microparticles produced with different methods," Biomaterials, 20, 1427-1435, 1999.
21. Y.N. Xia and G.M. Whitesides, "Soft lithography," Angewandte Chemie-International Edition, 37, 551-575, 1998.
22. L. Martynova, L.E. Locascio, M. Gaitan, G.W. Kramer, R.G. Christensen, and W.A. MacCrehan, "Fabrication of plastic microfluid channels by imprinting methods," Analytical Chemistry, 69, 4783-4789, 1997.
23. H. Becker and U. Heim, "Polymer hot embossing with silicon master structures," Sensors and Materials, 11, 297-304, 1999.
24. M. Heckele, W. Bacher, and K.D. Muller, "Hot embossing - The molding technique for plastic microstructures," Microsystem Technologies, 4, 122-124, 1998.
25. H. Becker and U. Heim, "Hot embossing as a method for the fabrication of polymer high aspect ratio structures," Sensors and Actuators a-Physical, 83, 130-135, 2000.
26. S.Y. Chou, P.R. Krauss, and P.J. Renstrom, "Imprint lithography with 25-nanometer resolution," Science, 272, 85-87, 1996.
27. R.W. Jaszewski, H. Schift, J. Gobrecht, and P. Smith, "Hot embossing in polymers as a direct way to pattern resist," Microelectronic Engineering, 42, 575-578, 1998.
28. L.E. Locascio, C.E. Perso, and C.S. Lee, "Measurement of electroosmotic flow in plastic imprinted microfluid devices and the effect of protein adsorption on flow rate," Journal of Chromatography A, 857, 275-284, 1999.
29. M. Rode and B. Hillerich, "Self-aligned positioning of microoptical components by precision prismatic grooves impressed into metals," Journal of Microelectromechanical Systems, 8, 58-64, 1999.
30. G.B. Lee, S.H. Chen, G.R. Huang, W.C. Sung, and Y.H. Lin, "Microfabricated plastic chips by hot embossing methods and their applications for DNA separation and detection," Sensors and Actuators B-Chemical, 75, 142-148, 2001.
31. R.M. McCormick, R.J. Nelson, M.G. AlonsoAmigo, J. Benvegnu, and H.H. Hooper, "Microchannel electrophoretic separations of DNA in injection-molded plastic substrates," Analytical Chemistry, 69, 2626-2630, 1997.
32. L.J. Lee, M.J. Madou, K.W. Koelling, S. Daunert, S. Lai, C.G. Koh, Y.J. Juang, Y. Lu, and L. Yu, "Design and fabrication of CD-like microfluidic platforms for diagnostics: Polymer-based microfabrication," Biomedical Microdevices, 3, 339-351, 2001.
33. L.Y. Yu, C.G. Koh, L.J. Lee, K.W. Koelling, and M.J. Madou, "Experimental investigation and numerical simulation of injection molding with micro-features," Polymer Engineering and Science, 42, 871-888, 2002.
34. D. Yao and B. Kim, "Development of rapid heating and cooling systems for injection molding applications," Polymer Engineering and Science, 42, 2471-2481, 2002.
35. C.H. Wu, C.H. Chen, K.W. Fan, W.S. Hsu, and Y.C. Lin, "Design and fabrication of polymer microfluidic substrates using the optical disc process," Sensors and Actuators a-Physical, 139, 310-317, 2007.
36. P.J. Crosland-Taylor, "A device for counting small particles suspended in a fluid through a tube," Nature, 171, 37-38, 1953.
37. D.A. Drew and R.T. Lahey, "Phase-distribution mechanisms in turbulent low-quality 2-phase flow in a circular pipe," Journal of Fluid Mechanics, 117, 91-106, 1982.
38. R. Rodriguez-Trujillo, C.A. Mills, J. Samitier, and G. Gomila, "Low cost micro-Coulter counter with hydrodynamic focusing," Microfluidics and Nanofluidics, 3, 171-176, 2007.
39. S.L. Anna, N. Bontoux, and H.A. Stone, "Formation of dispersions using "flow focusing" in microchannels," Applied Physics Letters, 82, 364-366, 2003.
40. V. Cristini and Y.C. Tan, "Theory and numerical simulation of droplet dynamics in complex flows - A review," Lab on a Chip, 4, 257-264, 2004.
41. Y.C. Tan, J.S. Fisher, A.I. Lee, V. Cristini, and A.P. Lee, "Design of microfluidic channel geometries for the control of droplet volume, chemical concentration, and sorting," Lab on a Chip, 4, 292-298, 2004.
42. Y.C. Tan and A.P. Lee, "Microfluidic separation of satellite droplets as the basis of a monodispersed micron and submicron emulsification system," Lab on a Chip, 5, 1178-1183, 2005.
43. Y.C. Tan, V. Cristini, and A.P. Lee, "Monodispersed microfluidic droplet generation by shear focusing microfluidic device," Sensors and Actuators B-Chemical, 114, 350-356, 2006.
44. K. Hettiarachchi, E. Talu, M.L. Longo, P.A. Dayton, and A.P. Lee, "On-chip generation of microbubbles as a practical technology for manufacturing contrast agents for ultrasonic imaging," Lab on a Chip, 7, 463-468, 2007.
45. I. Kobayashi, S. Mukataka, and M. Nakajima, "Novel asymmetric through-hole array microfabricated on a silicon plate for formulating monodisperse emulsions," Langmuir, 21, 7629-7632, 2005.
46. S. Sugiura, T. Oda, Y. Izumida, Y. Aoyagi, M. Satake, A. Ochiai, N. Ohkohchi, and M. Nakajima, "Size control of calcium alginate beads containing living cells using micro-nozzle array," Biomaterials, 26, 3327-3331, 2005.
47. K. Liu, H.J. Ding, J. Liu, Y. Chen, and X.Z. Zhao, "Shape-controlled production of biodegradable calcium alginate gel microparticles using a novel microfluidic device," Langmuir, 22, 9453-9457, 2006.
48. H. Zhang, E. Tumarkin, R. Peerani, Z. Nie, R.M.A. Sullan, G.C. Walker, and E. Kumacheva, "Microfluidic production of biopolymer microcapsules with controlled morphology," Journal of the American Chemical Society, 128, 12205-12210, 2006.
49. H. Zhang, E. Tumarkin, R.M.A. Sullan, G.C. Walker, and E. Kumacheva, "Exploring microfluidic routes to microgels of biological polymers," Macromolecular Rapid Communications, 28, 527-538, 2007.
50. X.D. Liu, D.C. Bao, W.M. Xue, Y. Xiong, W.T. Yu, X.J. Yu, X.J. Ma, and Q. Yuan, "Preparation of uniform calcium alginate gel beads by membrane emulsification coupled with internal gelation," Journal of Applied Polymer Science, 87, 848-852, 2003.
51. C.M. Silva, A.J. Ribeiro, M. Figueiredo, D. Ferreira, and F. Veiga, "Microencapsulation of hemoglobin in chitosan-coated alginate microspheres prepared by emulsification/internal gelation," Aaps Journal, 7, E903-E913, 2005.
52. K. Avgoustakis, A. Beletsi, Z. Panagi, P. Klepetsanis, A.G. Karydas, and D.S. Ithakissios, "PLGA-mPEG nanoparticles of cisplatin: In vitro nanoparticle degradation, in vitro drug release and in vivo drug residence in blood properties," Journal of Controlled Release, 79, 123-135, 2002.
53. K.S. Huang, T.H. Lai, and Y.C. Lin, "Manipulating the generation of Ca-alginate microspheres using microfluidic channels as a carrier of gold nanoparticles," Lab on a Chip, 6, 954-957, 2006.
54. K.S. Huang, T.H. Lai, and Y.C. Lin, "Using a microfluidic chip and internal gelation reaction for monodisperse calcium alginate microparticles generation," Frontiers in Bioscience, 12, 3061-3067, 2007.
55. J.H. Xu, S. Li, G.G. Chen, and G.S. Luo, "Formation of monodisperse microbubbles in a microfluidic device," Aiche Journal, 52, 2254-2259, 2006.
56. J.H. Xu, S.W. Li, J. Tan, Y.J. Wang, and G.S. Luo, "Preparation of highly monodisperse droplet in a T-junction microfluidic device," Aiche Journal, 52, 3005-3010, 2006.
57. J.H. Xu, G.S. Luo, S.W. Li, and G.G. Chen, "Shear force induced monodisperse droplet formation in a microfluidic device by controlling wetting properties," Lab on a Chip, 6, 131-136, 2006.
58. F.P. Bretherton, "The motion of long bubbles in tubes," Journal of Fluid Mechanics, 10, 166-188, 1961.
59. K.S. Huang, M.K. Liu, C.H. Wu, Y.T. Yen, and Y.C. Lin, "Calcium alginate microcapsules generation on a microfluidic system fabricated using the optical disk process," Journal of Micromechanics Microengineering, 17, 1428-1434, 2007.