PARTICLE SEPARATION, CHEMICAL GRADIENT CONTROL AND MICROMIXING VIA FOCUSED TRAVELLING SURFACE ACOUSTIC WAVES (F-TSAW)
- 1. Ghulam Destgeer Graduate student PARTICLE SEPARATION, CHEMICAL GRADIENT CONTROL AND MICROMIXING VIA FOCUSED TRAVELLING SURFACE ACOUSTIC WAVES (F-TSAW) Prof. Hyung Jin Sung Flow Control Laboratory Department of Mechanical Engineering, KAIST, Daejeon, South Korea.
- 2. 2/18 Questions! ? How can we 1. Separate particles! 2. Generate chemical gradient! 3. Mix fluids! inside a PDMS microfluidic channel with continuous flow via focused travelling surface acoustic waves???
- 3. 3/18 How surface acoustic waves work! We do need 1. Piezoelectric substrate (LiNbO3) 2. Interdigitated metallic (Au) electrodes deposited on top of LiNbO3 substrate 3. High frequency AC signal 4. Frequency of SAW = AC signal Maximum energy is transmitted in the forward direction. Very little energy is transmitted in the backward direction. SAW /8 /43/16 SAW Single phase unidirectional transducer (SPUDT) ˦/4 SAW SAW Interdigitated transducer (IDT) ? Surface acoustic wave (Rayleigh wave) propagates on the surface of solid piezoelectric substrate (LiNbO3) <Animation courtesy of Dr. Dan Russell, Grad. Prog. Acoustics, Penn State> LiNbO3 LiNbO3
- 4. 4/18 Particle separation Standing surface acoustic waves (SSAW) ? Two IDTs are required ? Tight microchannel alignment is needed ? Position of pressure nodes is critical Travelling surface acoustic waves (TSAW) ? Single F-IDT is used ? Loosely aligned microchannel can also work ? Position of pressure nodes is not important <Shi et al., 2008, Lab Chip> <Destgeer et al., 2013, Lab Chip>
- 5. 5/18 Particle separation via F-TSAW ? Continuous separation of particles in a PDMS microfluidic channel via focused TSAW <Destgeer et al., 2013, Lab Chip> ? ???? ?6
- 6. 6/18 Particle separation via F-TSAW ? Acoustic streaming flow (ASF) vs. acoustic radiation force (ARF) ? Polymer particles are dispersed in DI water <Destgeer et al., 2013, Lab Chip> Particles diameter 1 and 5?m ? 1?m particles are dominated by ASF ? 5?m particles are dominated by ARF Particles diameters 3 and 10?m
- 7. 7/18 Particle separation via F-TSAW ? Experimental conditions: C Frequency: 133.3MHz, Power: 225mW C -channel h x w: 40 m x 200 m C Flow rate (Q): 100L/h (3.5mm/s) C -particles diameter: 3 and 10m <Destgeer et al., 2013, Lab Chip> 500 ?m
- 8. 8/18 Particle separation efficiency ? TSAW OFF: all of the particles are collected at the same outlet ? TSAW ON: 100% of the 10?m particles passed through a separate outlet. <Destgeer et al., 2013, Lab Chip> For 10 ?m particles
- 9. 9/18 Particle separation comparison ? By focused IDT C Flow: 3.5mm/s C Input power: 235mW C PowerCVelocity ratio (RF): 67mW/(mm/s) ? By straight IDT C Flow: 4.6mm/s C Input power: 870mW C PowerCVelocity ratio (RS): 190mW/(mm/s) ? Comparison: C RS/RF=2.84 C RS 3 x RF TSAW TSAW Flow 2. Separation by straight IDT 1. Separation by focused IDT
- 10. 10/18 Chemical gradient generators <Jeon et al., 2000, Langmuir (a)> <Irimia et al., 2006, Anal Chem (b) & Lab Chip (c)> <Ahmed et al., 2013, Lab Chip (d)> (b). Universal gradient generator (d). Acoustofluidic oscillating bubbles based gradient generator (c). Microstructured membranes based fast switching gradient generator (a). Premixing gradient generator
- 11. 11/18 Gradient generation via F-TSAW ? Adjustable, rapidly switching microfluidic gradient generation using F-TSAW <Destgeer et al., Submitted>
- 12. 12/18 Gradient generation via F-TSAW ? Characterization of the chemical concentration gradient profiles ? Microchannel w x h: 500 x 140 ?m ? Flow rate: 1,000 ?L/h + 100 ?L/h = 1,100 ?L/h (4.37mm/s) <Destgeer et al., Submitted> Owls eyes vortices for gradient generation
- 13. 13/18 Gradient generation via F-TSAW ? Temporal control over the gradient profile with a fast switching frequency of 0.25 Hz. ? Gradient switching frequency is better then Ahmed et al. 2013 (0.1 Hz) and Irimia et al. 2006 <Destgeer et al., Submitted>
- 14. 14/18 Gradient generation ? The formation of acoustic streaming flow in a stationary and moving fluid ? The generation of fast switching chemical gradient profile <Destgeer et al., Submitted> Slowed down
- 15. 15/18 Gradient generation & micromixing ? Chemical gradient generation and uniform mixing of fluids inside a PDMS microfluidic channel. ? The plots indicate the normalized concentration of DI water (white) or rhodamine (gray) at any particular location in microchannel.
- 16. 16/18 Summary ? The presented F-TSAW micro-chip combined I. Label free continuous particle separation, II. Adjustable, rapidly switching chemical gradient generation and III. Uniform micromixing in a PDMS microfluidic channel. ? Particles are separated based upon their size difference under the influence of ARF. ? ASF generated symmetrical vortices C responsible for the controlled chemical gradient generation and uniform mixing of two fluids. ? A straight IDT would not be able to form strong ASF and separation would require higher power input.
- 17. 17/18 Contributors ? Principal Investigator: Prof. Hyung Jin Sung ? Researchers: Ghulam Destgeer, Sunghyuk Im, Byung Hang Ha, Jin Ho Jung, Hyun Wook Kang, Kyung Heon Lee, Mubashshir Ahmad Ansari ? Collaborator: Dr. Anas Alazzam, KUSTAR, UAE ? Funding: Creative Research Initiative Project, Korea. KAIST-KUSTAR Institute, Korea. Research areas at Flow Control Lab (flow.kaist.ac.kr) 1. Turbulence 2. Flow-Flexible Body Interaction 3. Acouto/Opto Microfluidics 4. Microprinting
- 18. THANK YOU FOR YOUR ATTENTION!!!