The Effect of Random Roughness on Fluid Flow in Microfluidic Channels

1. Iowa State University College of EngineeringSPEED ProgramSummer Program for Enhancing Engineering Development SPEED The Effect of Random Roughness on Fluid Flow in Microfluidic Channels Roslyn Melookaran MoSAIc Department of Mechanical Engineering Dr. Sundararajan, Jing Ren

2. SPEED Outline -Introduction/Motivation -Past experiments -Objectives -Fabrication process -Particle Image Velocimetry (PIV) -Results -Conclusion -Acknowledgments -Speed Experience

3. Motivation Microchannels are seen in many areas of engineering throughout the world Ink Jet printers Bio-analytical Instruments Fluid Logic systems A particular issue with these microchannels is that their decreased size allows for surface roughness to have an increased affect on fluid flow. Meinhart C D; Wereley S T; Santiago J G. PIV Measurements of a Microchannel Flow (1999)

4. Experiments in the Past • The majority of experiments in the past have dealt with the effects that predetermined roughness has on fluid flow. • Few have studied the effect that random roughness has on fluid flow. SPEED James T; Carrano A; Kandlikar S. Characterization of the effect of surface roughness and texture on fluid-Past, Present, and Future (2006).

5. SPEED Objectives Gain an understanding of micro fluidic devices, and how they are fabricated through research and observation in the lab. Gain an understanding of the PIV technique. Investigate the effect of random roughness on micro channel fluid flows using the PIV technique. Become familiarized with the PIV data analysis and presentation

6. PDMS 1. SU-8 2. Fabrication Process 3. Mix Polydimethylsiloxane (PDMS) curing agent to PDMS monomers- 1:10 ratio Degas in a vacuum for about an hour depending on the amount. Pour liquid PDMS onto a surface containing negative of the pattern (SU-8 layered on silicon wafer). Place the PDMS in curing oven for 4 to 8 hours Remove PDMS from wafer, and cut excess PDMS off. Bond the PDMS with clean glass slide using plasma bonder. SU-8 PDMS PDMS SU-8 4. PDMS Etched Glass Slide

7. SMOOTH ROUGH L 1 L z-m dx Ra= 0 SPEED

8. SPEED Particle Image Velocimetry (PIV) The camera is continuously taking pictures within time intervals as short as 500ns. Using the images taken, the displacement is estimated for the particle’s movement.

9. CHANNEL 2.5 cm SPEED Middle Of Channel 200 μm GLASS SLIDE

10. SMOOTH ROUGH SPEED 8 µm above surface

11. SMOOTH ROUGH SPEED 8 µm above surface

12. SMOOTH ROUGH SPEED MIDDLE

13. SMOOTH ROUGH SPEED MIDDLE

14. We found that this random roughness does have an effect on fluid flow. • No one has ever studied this before • What I’ve learned • Research process • PIV technique • What surface roughness is • Parameters used to measure it • PATIENCE! • Future Work • Test the channels with lower velocities SPEED Conclusion&Future Work

15. Dr. Sundararajan & Jing Ren • Research Experience for Undergraduates (REU) • The SPEED Program • Dr. Rollins • Lynn Lundy Evans • Laura Centeno-Diaz • Counselors – Isaac, Lindsey, Christine • All the SPEED participants Acknowledgments

16. SPEED EXERIENCE

17. SPEED STRAWberry Construction!!!

18. SPEED