In this study, a cell-in-droplet encapsulation using dean flow in spiral microchannel device is applied for microalgae separation. Researchers are interested in separating microparticles by using microfluidic chips in recent years due to great advantages for variety kinds of related applications such as biotechnology, medical examinations, or cell studies. However, the main disadvantage of these microfluidic chips is that it usually would experience particles clogging which reduces the separation yield and hard for particles investigation. The microfluidic chip being introduced in this study is a combination of 2 distinct designs: (1) spiral microchannel design used for separating different sizes of microalgae and (2) microdroplet generation design used for cell encapsulation. The reason is to enhance the separation yield by using different dominant forces concept (Dean drag force and lift force) in spiral microchannel design together with microdroplet generation design narrow down the volume for easier cell observation.
The microfluidic chip was fabricated by using soft lithography techniques. Polydimethylsiloxane (PDMS) is well known as biocompatible material, low cost of production, disposable, more over it is transparency makes it possible to observe particles inside the microchannel clearly. Due to all of these benefits, this device might be an alternative for cell applications using droplet-based platforms.

In this study, a cell-in-droplet encapsulation using dean flow in spiral microchannel device is applied for microalgae separation. Researchers are interested in separating microparticles by using microfluidic chips in recent years due to great advantages for variety kinds of related applications such as biotechnology, medical examinations, or cell studies. However, the main disadvantage of these microfluidic chips is that it usually would experience particles clogging which reduces the separation yield and hard for particles investigation. The microfluidic chip being introduced in this study is a combination of 2 distinct designs: (1) spiral microchannel design used for separating different sizes of microalgae and (2) microdroplet generation design used for cell encapsulation. The reason is to enhance the separation yield by using different dominant forces concept (Dean drag force and lift force) in spiral microchannel design together with microdroplet generation design narrow down the volume for easier cell observation.
The microfluidic chip was fabricated by using soft lithography techniques. Polydimethylsiloxane (PDMS) is well known as biocompatible material, low cost of production, disposable, more over it is transparency makes it possible to observe particles inside the microchannel clearly. Due to all of these benefits, this device might be an alternative for cell applications using droplet-based platforms.

Table of Contents
Abstract 3
List of Tables 5
List of Figures 6
CHAPTER I INTRODUCTION 10
1.1 Background 10
1.2 Research Objectives 12
CHAPTER II LITERATURE REVIEW 13
2.1 Continuous Particle Separation in Spiral Microchannels using Deal flows and Differential Migration[1] 14
2.2 Microfluidic Platforms for Size-Based Cell Sorting[25] 17
2.3 A Microfluidic Device for On-Chip agarose Microbeads Generation with Ultralow Reagent Consumption[26] 22
2.4 High-Yield Cell Ordering and Deterministic Cell-in-Droplet Encapsulation Using Dean Flow in a Curved Microchannel[24] 26
2.5 Literature Conclusion 29
CHAPTER III METHODOLOGY 30
3.1 Theory 30
3.1.1 Dean Number 30
3.1.2 Forces in the microchannel 31
3.2 Device Design 33
3.2.1 Spiral Microfluidics Design 33
3.2.2 Microdroplets Generation Microfluidic Design 36
3.2.3 The Combined Microfluidics Chip Design 38
3.3 Device Fabrication 40
3.3.1 Mold Fabrication 41
3.3.2 PDMS Fabrication 47
3.3.3 Microfluidic Chip Bonding 49
3.4 Sample Used in the Experiment 51
3.4.1 Cosmarium 51
3.4.2 Chlorella 52
CHAPTER IV EXPERIMENTS 54
4.1 ANSYS/Fluent Simulations 54
4.2 Microdroplets Generation 59
4.3 Spiral Microfluidic Design 68
4.4 The Final Set-Up for the Experiments 70
CHAPTER V RESULTS AND DISCUSSION 72
5.1 Results and Discussion 72
5.1.1 Old Designs 72
5.1.2 Calculations and ANSYS Simulations 75
5.1.3 The Combination Microfluidics Chip Design 76
5.2 Conclusion 82
5.3 Future Work 83
CHAPTER VI REFERENCES 85

CHAPTER VI REFERENCES
[1] A. A. S. Bhagat, S. S. Kuntaegowdanahalli, and I. Papautsky, "Continuous particle separation in spiral microchannels using dean flows and differential migration," Lab on a Chip, vol. 8, pp. 1906-1914, 2008.
[2] J. Giddings, "Field-flow fractionation: analysis of macromolecular, colloidal, and particulate materials," Science, vol. 260, pp. 1456-1465, June 4, 1993 1993.
[3] E. Chmela, R. Tijssen, M. T. Blom, H. J. G. E. Gardeniers, and A. van den Berg, "A Chip System for Size Separation of Macromolecules and Particles by Hydrodynamic Chromatography," Analytical Chemistry, vol. 74, pp. 3470-3475, 2002/07/01 2002.
[4] 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, 2004/09/01 2004.
[5] X. Xu, K. K. Caswell, E. Tucker, S. Kabisatpathy, K. L. Brodhacker, and W. A. Scrivens, "Size and shape separation of gold nanoparticles with preparative gel electrophoresis," Journal of Chromatography A, vol. 1167, pp. 35-41, 10/5/ 2007.
[6] M. Dürr, J. Kentsch, T. Müller, T. Schnelle, and M. Stelzle, "Microdevices for manipulation and accumulation of micro- and nanoparticles by dielectrophoresis," ELECTROPHORESIS, vol. 24, pp. 722-731, 2003.
[7] A. Nilsson, F. Petersson, H. Jonsson, and T. Laurell, "Acoustic control of suspended particles in micro fluidic chips," Lab on a Chip, vol. 4, pp. 131-135, 2004.
[8] J. P. Brody and P. Yager, "Diffusion-based extraction in a microfabricated device," Sensors and Actuators A: Physical, vol. 58, pp. 13-18, 1// 1997.
[9] P. Jandik, B. H. Weigl, N. Kessler, J. Cheng, C. J. Morris, T. Schulte, et al., "Initial study of using a laminar fluid diffusion interface for sample preparation in high-performance liquid chromatography," Journal of Chromatography A, vol. 954, pp. 33-40, 4/19/ 2002.
[10] L. R. Huang, E. C. Cox, R. H. Austin, and J. C. Sturm, "Continuous Particle Separation Through Deterministic Lateral Displacement," Science, vol. 304, pp. 987-990, May 14, 2004 2004.
[11] D. W. Inglis, J. A. Davis, R. H. Austin, and J. C. Sturm, "Critical particle size for fractionation by deterministic lateral displacement," Lab on a Chip, vol. 6, pp. 655-658, 2006.
[12] J. P. Beech and J. O. Tegenfeldt, "Tuneable separation in elastomeric microfluidics devices," Lab on a Chip, vol. 8, pp. 657-659, 2008.
[13] I. Gregoratto, C. J. McNeil, and M. W. Reeks, "Micro-devices for rapid continuous separation of suspensions for use in micro-total-analysis-systems (μTAS)," 2007, pp. 646503-646503-8.
[14] J. Seo, M. H. Lean, and A. Kole, "Membraneless microseparation by asymmetry in curvilinear laminar flows," Journal of Chromatography A, vol. 1162, pp. 126-131, 8/31/ 2007.
[15] J. Seo, M. H. Lean, and A. Kole, "Membrane-free microfiltration by asymmetric inertial migration," Applied Physics Letters, vol. 91, pp. -, 2007.
[16] D. Di Carlo, D. Irimia, R. G. Tompkins, and M. Toner, "Continuous inertial focusing, ordering, and separation of particles in microchannels," Proceedings of the National Academy of Sciences, vol. 104, pp. 18892-18897, November 27, 2007 2007.
[17] D. Di Carlo, J. F. Edd, D. Irimia, R. G. Tompkins, and M. Toner, "Equilibrium Separation and Filtration of Particles Using Differential Inertial Focusing," Analytical Chemistry, vol. 80, pp. 2204-2211, 2008/03/01 2008.
[18] S. S. Kuntaegowdanahalli, A. A. S. Bhagat, G. Kumar, and I. Papautsky, "Inertial microfluidics for continuous particle separation in spiral microchannels," Lab on a Chip, vol. 9, pp. 2973-2980, 2009.
[19] G. Segré and A. Silberberg, "Behaviour of macroscopic rigid spheres in Poiseuille flow Part 2. Experimental results and interpretation," Journal of Fluid Mechanics, vol. 14, pp. 136-157, 1962.
[20] G. Segre and A. Silberberg, "Radial Particle Displacements in Poiseuille Flow of Suspensions," Nature, vol. 189, pp. 209-210, 01/21/print 1961.
[21] A. Bhagat, S. Kuntaegowdanahalli, and I. Papautsky, "Inertial microfluidics for continuous particle filtration and extraction," Microfluidics and Nanofluidics, vol. 7, pp. 217-226, 2009/08/01 2009.
[22] A. A. S. Bhagat, S. S. Kuntaegowdanahalli, and I. Papautsky, "Enhanced particle filtration in straight microchannels using shear-modulated inertial migration," Physics of Fluids (1994-present), vol. 20, pp. -, 2008.
[23] A. E. Hasni, K. Göbbels, A. L. Thiebes, P. Bräunig, W. Mokwa, and U. Schnakenberg, "Focusing and Sorting of Particles in Spiral Microfluidic Channels," Procedia Engineering, vol. 25, pp. 1197-1200, // 2011.
[24] E. W. M. Kemna, R. M. Schoeman, F. Wolbers, I. Vermes, D. A. Weitz, and A. van den Berg, "High-yield cell ordering and deterministic cell-in-droplet encapsulation using Dean flow in a curved microchannel," Lab on a Chip, vol. 12, pp. 2881-2887, 2012.
[25] S. Karunanidhi, M. W. Lum, S. R. Nagurla, and W. C. Tang, "Microfluidic platforms for size-based cell sorting," in Nano/Molecular Medicine and Engineering (NANOMED), 2013 IEEE 7th International Conference on, 2013, pp. 27-31.
[26] L. Desbois, A. Padirac, S. Kaneda, A. J. Genot, Y. Rondelez, D. Hober, et al., "A microfluidic device for on-chip agarose microbead generation with ultralow reagent consumption," Biomicrofluidics, vol. 6, pp. -, 2012.
[27] S. Ookawara, D. Street, and K. Ogawa, "Numerical study on development of particle concentration profiles in a curved microchannel," Chemical Engineering Science, vol. 61, pp. 3714-3724, 6// 2006.
[28] S. Marija and H. Dieter, "Sensitivity of photosynthesis to UV radiation in several Cosmarium strains (Zygnematophyceae, Streptophyta) is related to their geographical distribution," Photochemical & Photobiological Sciences, vol. 13, pp. 1066-1081, 2014.
[29] M. Stamenković, E. Woelken, and D. Hanelt, "Ultrastructure of Cosmarium strains (Zygnematophyceae, Streptophyta) collected from various geographic locations shows species-specific differences both at optimal and stress temperatures," Protoplasma, vol. 251, pp. 1491-1509, 2014/11/01 2014.
[30] P. Neale, "Species-Specific Responses to Combined Thermal-irradiance Stress in Microalgae – “Each is to its Own”," Photochemistry and Photobiology, vol. 89, pp. 822-823, 2013.
[31] I. Zelitch, "9 - Relation of Photosynthesis, Total Respiration, and other Factors to Control of Productivity in Stands," in Photosynthesis, Photorespiration, and Plant Productivity, I. Zelitch, Ed., ed: Academic Press, 1971, pp. 267-299.
[32] W. Belasco, "Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine," Technology and Culture, vol. 38, pp. 608-634, 1997.
[33] M. Capdevila, A. Maestro, M. Porras, and J. M. Gutiérrez, "Preparation of Span 80/oil/water highly concentrated emulsions: Influence of composition and formation variables and scale-up," Journal of Colloid and Interface Science, vol. 345, pp. 27-33, 5/1/ 2010.
[34] H. Wangqi and K. D. Papadopoulos, "Stability of water-in-oil-in-water type globules," Chemical Engineering Science, vol. 51, pp. 5043-5051, 11// 1996.
[35] R. Davies, D. E. Graham, and B. Vincent, "Water-cyclohexane-“Span 80”-“Tween 80” systems: Solution properties and water/oil emulsion formation," Journal of Colloid and Interface Science, vol. 116, pp. 88-99, 3// 1987.