本研究利用理論方法及數值模擬分析微管道中以電滲流驅動之溶液取代現象，並應用於評估微管道中壁面的界面電位，進而探討聚二甲基矽氧烷（polydimethylsiloxane, PDMS）微管道內蛋白質的吸附行為。
在理論分析中，探討了溶液導電度差異在均質微管道內之溶液取代過程中所扮演的角色，也分析擴散作用產生之混合區對於溶液取代速度與暫態電流變化的影響，結果顯示混合區的存在對溶液取代速度沒有影響，僅會稍微提升管道內的電流值。此外，還討論當微管道壁面具高電荷密度時，表面電導效應對溶液取代行為的影響。若以對離子價數高之低導電度溶液取代對離子價數低之高導電度溶液，於特定微管道尺寸下，理論分析顯示低導電度溶液的有效導電度可能會大於高導電度溶液的有效導電度，此時暫態電流變化趨勢與一般微管道尺度下的相反。
在數值模擬分析中，以二維管道為模型，評估在不同情況下，如微管道長高比、微管道上下壁面電性與溶液導電度差異，微管道中溶液的濃度分佈與暫態電流變化。於上下壁面具不同界面電位差異的非均質管道中，混合區內的濃度分佈及暫態電流變化明顯受到水平擴散效應、垂直擴散效應和剪切位移效應之交互作用的影響。另外，當垂直擴散效應與剪切位移效應相當時，由垂直速度梯度引發的泰勒分散現象變得較明顯。
在微管道之PDMS與玻璃壁面的界面電位評估中，比較電流觀測法實驗與理論分析及數值模擬得到的電流-時間曲線，最佳化所得的界面電位與經驗式的預測有良好的吻合度。在非均質微管道中，當垂直擴散效應明顯時，各材質壁面的界面電位與平均界面電位則可以用一關係式來描述，此關係式有助於快速評估各壁面的界面電位。
本研究還以電流觀測法分析牛血漿白蛋白於PDMS微管道壁面上的吸附現象，結果顯示其吸附行為可用Langmuir adsorption isotherm來描述。

In this study, theoretical and numerical approaches were used to analyze the phenomena of solution displacement driven by electro-osmotic flow in microchannels. The approaches were also applied to evaluate the zeta potentials of microchannel walls and then to investigate the protein adsorption behavior in polydimethylsiloxane (PDMS) microchannels.
In the theoretical analysis, the roles of solution conductivity difference in the solution displacement in a uniformly charged microchannel were examined. Influence of the mixing zone induced by diffusion on the solution displacement speed and transient current was also analyzed. The results demonstrated that the presence of the mixing zone had no effect on the solution displacement speed and only slightly increased the transient current. In addition, the effects of surface conductance on the solution displacement in microchannels with high charge density walls were discussed. For a lower conductivity solution with a higher ionic valence displacing a higher conductivity solution with a lower ionic valence, the theoretical analysis indicated that the effective conductivity of the lower conductivity solution might exceed that of the higher conductivity solution at specific microchannel dimensions. The resulting trend of the transient current variation was then opposite to that observed in microchannels with regular dimensions.
In the numerical analysis with a 2-dimensional microchannel model, solution concentration distributions and transient current variations at different conditions, such as aspect ratio of the microchannel, charge characteristics of microchannel walls and solution conductivity difference, were evaluated. For non-uniformly charged microchannel walls with different zeta potential difference, the solution concentration distributions and current-time curves were apparently affected by the interactions of transverse diffusion, longitudinal diffusion, and shear convection. In addition, when the extent of transverse diffusion was similar to that of shear convection, the Taylor dispersion induced by the transverse velocity gradient became pronounced.
For the zeta potential evaluation of PDMS and glass surfaces in microchannels, the experimental current-time curves were compared with those obtained from the theoretical and numerical models. The best-fit zeta potentials were found to be in good agreement with the predictions from the correlations. In the microchannels with non-uniformly charged surfaces, when the transverse diffusion is significant, a relationship between respective zeta potentials of the surfaces and the average zeta potential can be established, which is useful for the quick estimation of zeta potentials of the surfaces.
This study also analyzed the bovine serum albumin (BSA) adsorption behavior on the PDMS microchannel surface by the current monitoring method. The results indicated that the adsorption behavior of BSA could be described by the Langmuir adsorption isotherm.

Aris, R., “On the Dispersion of a Solute in a Fluid Flowing through a Tube,” Proc. R. Soc. Lond. A 235, 67-77, 1956.
Arulanandam, S. and Li, D., “Determining ζ Potential and Surface Conductance by Monitoring the Current in Electro-Osmotic Flow,” J. Colloid Interface Sci. 225, 421-428, 2000.
Bartzoka, V., Brook, M.A., and McDermott, M.R., “Silicone-Protein Films: Establishing the Strength of the Protein-Silicone Interaction,” Langmuir 14, 1892-1898, 1998.
Bodas, D. and Khan-Malek, C., “Hydrophilization and Hydrophobic Recovery of PDMS by Oxygen Plasma and Chemical Treatment-An SEM Investigation,” Sens. Actuators B 123, 368-373, 2007.
Borukhov, I. and Andelman, D., “Steric Effects in Electrolytes: A Modified Poisson-Boltzmann equation,” Phys. Rev. Lett. 79, 435-438, 1997.
Butler, J.E., Lü, E.P., Navarro, P., and Christiansen, B., “Comparative Studies on the Interation of Proteins with a Polydimethylsiloxane Elastomer. I. Monolayer Protein Capture Capacity (PCC) as a Function of Protein pI, Buffer pH and Buffer Ionic Strength,” J. Mol. Recognit. 10, 36-51, 1997.
Carter, D.C. and Ho, J.X., “Structure of Serum Albumin,” Adv. Protein Chem. 45, 153-203, 1994.
Chien, R.L. and Burgi, D.S., “Sample Stacking of an Extremely Large Injection Volume in High-Performance Capillary Electrophoresis,” Anal. Chem. 64, 1046-1050, 1992.
Das, S. and Chakraborty, S., “Effect of Conductivity Variations within the Electric Double Layer on the Streaming Potential Estimation in Narrow Fluidic Confinements,” Langmuir 26, 11589-11596, 2010.
Deen, W.M., Analysis of Transport Phenomena, Oxford University Press, London, 1998.
Devasenathipathy, S., and Santiago, J.G., “Particle Tracking Techniques for Electronkinetic Microchannel Flows,” Anal. Chem. 74, 3704-3713, 2002.
Devasenathipathy, S., Bharadwaj, R., and Santiago, J.G., “Investigation of Internal Pressure Gradients Generated in Electrokinetic Flows with Axial Conductivity Gradients,” Exp. Fluids 43, 959-967, 2007.
Duffy, D.C., McDonald, J.C., Schueller, O.J.A., and Whitesides, G.M., “Rapid Prototyping of Microfluidic Systems in Polydimethylsiloxane,” Anal. Chem. 70, 4974-4984, 1998.
Dukhin, S.S. and Derjaguin, B.V., Surface and Colloid Science, Wiley, New York, 1974.
Gas, B., Stedrý, M., and Kenndler, E., “Peak Broadening in Capillary Zone Electrophoresis,” Electrophoresis 18, 2123-2133, 1997.
Huang, X., Gordon, M.J., and Zare, R.N., “Current-Monitoring Method for Measuring the Electroosmotic Flow Rate in Capillary Zone Electrophoresis,” Anal. Chem. 60, 1837-1838, 1988.
Hunter, R.J., Foundations of Colloid Science, Oxford University Press, London, 1992.
Johnson, T.J., Ross, D., and Locascio, L.E., “Rapid Microfluidic Mixing,” Anal. Chem. 74, 45-51, 2002.
Kirby, B.J. and Hasselbrink, Jr. E.F., “Zeta Potential of Microfluidic Substrates: 1. Theory, Experimental Techniques, and Effects on Separations,” Electrophoresis 25, 187-202, 2004a.
Kirby, B.J. and Hasselbrink, Jr. E.F., “Zeta Potential of Microfluidic Substrates: 2. Data for Polymers,” Electrophoresis 25, 203-213, 2004b.
Kjellander, R., “Intricate Coupling between Ion-Ion and Ion-Surface Correlations in Double Layers as Illustrated by Charge Inversion-Combined Effects of Strong Coulomb Correlations and Excluded Volume,” J. Phys.: Condens. Matter 21, 424101, 2009.
Kuo, A.-T., Chang, C.-H., and Wei, H.-H., “Transient Currents in Electrolyte Displacement by Asymmetric Electro-osmosis and Determination of Surface Zeta Potentials of Composite Microchannels,” Appl. Phys. Lett. 92, 244102, 2008.
Laser, D.J. and Santiago, J.G., “A Review of Micropumps,” J. Micromech. Microeng. 14, R35-R64, 2004.
Li, C.H. and Harrison, D.J., “Transport, Manipulation, and Reaction of Biological Cells On-Chip Using Electrokinetic Effects,” Anal. Chem. 69, 1564-1568, 1997.
Locascio, L.E., Perso, C.E., and Lee, C.S., “Measurement of Electroosmotic Flow in Plastic Imprinted Microfluid Devices and Effect of Protein Adsorption on Flow Rate,” J. Chromatogr. A 857, 275-284, 1999.
Lyklema, J., Fundamentals of Interface and Colloid Science, Academic Press, London, 1995.
Maeng, J.H., Lee, B.C., Ko, Y.J., Cho, W., Ahn, Y., Cho, N.G., Lee, S.H., and Hwang, S.Y., “A Novel Microfluidic Biosensor Based on an Electrical Detection System for Alpha-Fetoprotein,” Biosens. Bioelectron. 23, 1319-1325, 2008.
Makamba, H., Kim, J.H., Lim, K., Park, N., and Hahn, J.H., “Surface Modification of Poly(dimethylsiloxane) Microchannels,” Electrophoresis 24, 3607-3619, 2003.
Matsui, T., Franzke, J., Manz, A., and Janasek, D., “Temperature Gradient Focusing in a PDMS/Glass Hybrid Microfluidic Chip,” Electrophoresis 28, 4606-4611, 2007.
McCormick, R.M., Nelson, R.J., Alonso-Amigo, M.G., Benvegnu, D.J., and Hooper, H.H., “Microchannel Electrophoretic Separations of DNA in Injection-Molded Plastic Substrates,” Anal. Chem. 69, 2626-2630, 1997.
Minor, M., van der Linde, A.J., van Leeuwen, H.P., and Lyklema, J., “Dynamic Aspects of Electrophoresis and Electroosmosis: A New Fast Method for Measuring Particle Mobilities, ” J. Colloid Interface Sci. 189, 370-375, 1997.
Niu, Z.Q., Chen, W.Y., Shao S.Y., Jia, X.Y., and Zhang W.P., “DNA Amplification on a PDMS-Glass Hybrid Microchip,” J. Micromech. Microeng. 16, 425-433, 2006.
Ocvirk, G., Munroe, M., Tang, T., Oleschuk, R., Westra, K., and Harrison, D.J., “Electrokinetic Control of Fluid Flow in Native Poly(dimethylsiloxane) Capillary Electrophoresis Devices,” Electrophoresis 21, 107-115, 2000.
Ostuni, E., Chapman, R.G., Liang, M.N., Meluleni, G., Pier, G., Ingber, D.E., and Whitesides, G.M., “Self-Assembled Monolayers That Resist the Adsorption of Proteins and the Adhension of Bacterial and Mammalian Cells,” Langmuir 17, 6336-6343, 2001.
Pearce, K.H., Hiskey, R.G., and Thompson, N.L., “Surface Binding Kinetics of Prothrombin Fragment 1 on Planar Membranes Measured by Total Internal Reflection Fluorescence Microscopy,” Biochemistry 31, 5983-5995, 1992.
Phillips, K.S. and Cheng, Q., “Microfluidic Immunoassay for Bacterial Toxins with Supported Phospholipid Bilayer Membranes on Poly(dimethylsiloxan),” Anal. Chem. 77, 327-334, 2005.
Pittman, J.L., Henry, C.S., and Gilman, S.D., “Experimental Studies of Electroosmotic Flow Dynamics in Microfabricated Devices during Current Monitoring Experiments,” Anal. Chem. 75, 361-370, 2003.
Probstein, R., Physicochemical Hydrodynamics, John Wiley & Son, New York, 1994.
Pu, Q., Yun, J., Temkin, H., and Liu, S., “Ion-Enrichment and Ion-Depletion Effect of Nanochannel Structures,” Nano Lett. 4, 1099-1103, 2004
Ramsden, J.J., “Experimental Methods for Investigating Protein Adsorption Kinetics at Surfaces,” Q. Rev. Biophys. 27, 41-105, 1993.
Ren, L., Escobedo, C., and Li, D., “Electroosmotic Flow in a Microcapillary with One Solution Displacing Another Solution,” J. Colloid Interface Sci. 242, 264-271, 2001.
Ren, L., Escobedo-Canseco, C., and Li, D., “A New Method of Evaluating the Average Electro-Osmotic Velocity in Microchannels,” J. Colloid Interface Sci. 250, 238-242, 2002.
Ren, L., Masliyah, J., and Li, D., “Experimental and Theoretical Study of the Displacement Process between Two Electrolyte Solutions in a Microchannel,” J. Colloid Interface Sci. 257, 85-92, 2003.
Sanders, R.S., Chow, R.S., and Masliyah, J.H., “Deposition of Bitumen and Asphaltene-Stabilized Emulsions in an Impinging Jet Cell,” J. Colloid Interface Sci. 174, 230-245, 1995.
Seller, K., Fan, Z. H., Fluri, K., and Harrison, D.J., “Electroosmotic Pumping and Valveless Control of Fluid Flow within a Manifold of Capillaries on a Glass Chip,” Anal. Chem. 66, 3485-3491, 1994.
Stein, D., Kruithof, M., and Dekker, C., “Surface-Charge-Governed Ion Transport in Nanofluidic Channels,” Phys. Rev. Lett. 93, 035901, 2004.
Tanaka, M., Mochizuki, A., Motomura, T., Shimura, K., Onishi, M., and Okahata, Y., “In situ Studies on Protein Adsorption onto a Poly(2-methoxyethylacrylate) Surface by a Quartz Crystal Microbalance,” Colloids Surf. A 193, 145-152, 2001.
Taylor, G.I., “Dispersion of Soluble Matter in Solvent Flowing Slowly through a Tube,” Proc. R. Soc. Lond. A 219, 186-203, 1953.
VanDelinder, V. and Groisman, A., “Separation of Plasma from Whole Human Blood in a Continuous Cross-Flow in a Molded Microfluidic Device,” Anal. Chem. 78, 3765-3771, 2006.
Van Doormal, J.P. and Raithby, G.D., “Enhancements of the SIMPLE Method for Predicting Incompressible Fluid Flows,” Numer. Heat Transfer 7, 147-163, 1984.
Wang, B., Abdulali-Kanji, Z., Dodwell, E., Horton, J.H., and Oleschuk, R.D., “Surface Characterization Using Chemical Force Microscopy and the Flow Performance of Modified Polydimethylsiloxane for Microfluidic Device Applications,” Electrophoresis 24, 1442-1450, 2003.
Wang, C., Wong, T.N., Yang, C., and Ooi, K.T., “Characterization of Electroosmotic Flow in Rectangular Microchannels,” Int. J. Heat Mass Transfer 50, 3115-3121, 2007.
Werner, C., and Jacobash, H.J., “Surface Characterization of Polymers for Medical Devices,” Int. J. Artificial Organs 22, 160-176, 1999.
Wu, D., Zhao, B., Dai, Z., Qin, J., and Lin, B., “Grafting Epoxy-Modified Hydrophilic Polymers onto Poly(dimethylsiloxane) Microfluidic Chip to Resist Nonspecific Protein Adsorption,” Lab Chip 6, 942-947, 2006.
Xia, Y., and Whitesides, G.M., “Soft Lithography,” Annu. Rev. Mater. Sci. 28, 153-184, 1998.
Yossifon. G., Chang. Y.C., and Chang, H.C., “Rectification, Gating Voltage, and Interchannel Communication of Nanoslot Arrays due to Asymmetric Entrance Space Charge Polarization,” Phys. Rev. Lett. 103, 154502, 2009.
Zheng, J., Li, H.W., and Yeung, E.S., “Manipulation of Single DNA Molecules via Lateral Focusing in a PDMS/Glass Microchannel,” J. Phys. Chem. B 108, 10357-10362, 2004.
郭安聰，具不同帶電面之微管道壁面ζ-potential的量測，成功大學化學工程學系碩士論文，2007。