Microfluidics project

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Microfluidics project

  1. 1. Serpent MixerFinal Presentation<br />Group B:WoohyuckChoi<br />
  2. 2. Introduction<br />Why is micromixing important?<br />Types of micromixing<br />Principles of micromixing<br />Module 1 (Optimization)<br />Module 2 (Fabrication)<br />Module 3 (Characterization)<br />Comparison to Simulation<br />Type of Mixing<br />Comparison to Other Mixer<br />Conclusions<br />Outline<br />
  3. 3. Consumes small amounts of valuable reagents<br />Mixes in relatively short periods of time<br />Applications in:<br />Lab-on-Chip devices<br />DNA sequencing<br />Sample preparation<br />Cell separation and detection<br />Protein folding<br />Why is Micromixing Important?<br />J. Ottino and S. Wiggins, "Designing optimal micromixers," Science (New York, N.Y.), vol. 305, pp. 485, 2004.<br />
  4. 4. Active<br />Utilizes disturbances created by external fields<br />Pressure, temperature, electrohydrodynamics, acoustics, electrokinetics etc…<br />Require external power sources (complex integration)<br />Passive<br />Rely totally on channel geometry<br />Simple, low cost, less likely to damage samples<br />Types of Micromixing<br />N. Nguyen T. and Z. Wu, "Micromixers - a review," Journal of Micromechanics, vol. 15, 2005.<br />
  5. 5. Molecular Diffusion<br />Increase contact area and decrease diffusion path<br />Parallel lamination<br />Hydrodynamic focusing<br />Chaotic Advection<br />Manipulate the laminar flow across boundary <br />Specific 3-D obstacles needed<br />Principles of Passive Micromixing<br />N. Nguyen T. and Z. Wu, "Micromixers - a review," Journal of Micromechanics, vol. 15, 2005. <br />S. Hardt, K. S. Drese, V. Hessel and F. Schonfeld, "Passive micromixers for applications in the microreactor and μTAS fields," Microfluidics and Nanofluidics, vol. 1, pp. 108-118, 2005.<br />
  6. 6. 2-D 3um triangular mesh<br />Values Chosen<br />Variable 1: 40um<br />Variable 2: 30um<br />Variable 3: 30um<br />Module 1 (Optimization)<br />Figure 1. Variables for optimization<br />
  7. 7. Simulated in 3-D with 5um triangular mesh.<br />Module 1 (Optimization) 2<br />Figure 3. σ vs downstream position for simulated channel<br />Figure 4. σ vs Re for simulated channel at 4910um downstream<br /> Percent Mixing at 4910um Pressure Drop:<br />Re=.1 99.58% 1.05KPa<br />Re=1 98.40% 10.7KPa<br />Re=10 99.9% 130Kpa <br />
  8. 8. SU-8 Master Mold<br />SU-8 2075 spun on clean 3 inch Si Wafer<br />Exposed with I-Line highpass filter 175 mJ/cm2 for 30 sec <br />Oxygen plasma descum <br />PDMS Casting<br />10:1 elastomer to curing agent mixture<br />Bonding<br />Corona discharge on both PDMS and microscope slide ¼ inch above samples for 20 sec<br />Module 2 (Fabrication) <br />
  9. 9. Module 2 (Fabrication) 2<br />7.387<br />30.31<br />40.01<br />60.38<br />50.01<br />33.54<br />Fig. 5 Critical dimensions of serpent mixer.<br />Table 1. Comparison of expected and fabricated channel dimensions<br />
  10. 10. Module 3 (Characterization)<br />Fig 6. Images taken at different positions in channel for Re=1 case.<br />
  11. 11. Module 3 (Characterization) 2<br />Figure 7. σ vs. downstream position for fabricated channel<br />Figure 8. σ vs Re for fabricated channel<br />Table 2. Percent mixing at approximately 1cm downstream<br />
  12. 12. Y(90) Position<br />Calculated using a 4th order polynomial fit<br />Re=.1 10895um<br />Re=1 12642um<br />Re=10 10729um<br />Module 3 (Characterization) 3<br />
  13. 13. Simulation was rerun for channel with fabricated dimensions.<br />2-D 2um triangular mesh was used for maximum accuracy<br />Comparison to Simulation<br />Table 3. Comparison of percent mixing at 4910um downstream<br />
  14. 14. Primarily diffusive <br />Re=0.1 best mixing<br />Not purely diffusive<br />Re=10 > Re=1<br />Vorticity present in bends<br />Likely due to race track effect<br />Type of Mixing<br />Figure 9. Vorticity in channel<br />
  15. 15. For almost the same Re and Pe values the staggered herringbone mixer achieved σ=.04 (92% Mixing) at 1cm downstream.<br />The Serpent mixer achieved 86.55% mixing<br />~5% decrease in mixing<br />Comparison to Other Mixer <br />A. D. Stroock, S. K. W. Dertinger, A. Ajdari, I. Mezic, H. A. Stone and G. M. Whitesides, "Chaotic Mixer for Microchannels," Science, vol. 295, pp. 647-651, January 25. 2002.<br />
  16. 16. The serpent mixer is a primarily diffusive mixer but due to sharp bends in the channel has some convective behavior.<br />Achieved 86.55% mixing at 1.06cm for Re=0.1<br />Projected to reach 90% mixing in just over 1cm downstream<br />May reach it sooner but a lot of error in calculations due to low number of data points.<br />Conclusions<br />
  17. 17. [1] J. Ottino and S. Wiggins, "Designing optimal micromixers," Science (New York, N.Y.), vol. 305, pp. 485, 2004. <br />[2] N. Nguyen T. and Z. Wu, "Micromixers - a review," Journal of Micromechanics, vol. 15, 2005. <br />[3] S. Hardt, K. S. Drese, V. Hessel and F. Schonfeld, "Passive micromixers for applications in the microreactor and μTAS fields," Microfluidics and Nanofluidics, vol. 1, pp. 108-118, 2005.<br />[4] A. D. Stroock, S. K. W. Dertinger, A. Ajdari, I. Mezic, H. A. Stone and G. M. Whitesides, "Chaotic Mixer for Microchannels," Science, vol. 295, pp. 647-651, January 25. 2002.<br />References<br />
  18. 18. Questions ?<br />

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