1. Micropumps/Microvavles

2. Outline Different types of micropumps  Mechanic pump Membrane pump Diffuser pump  Non-Mechanic pump Bubble pump Electrohydrodynamic (EHD) pump

3. Mechanical Pump In general, mechanical pump consists of moveable components, such as moveable valves, moveable membrane, moveable channel, etc. Mechanical pump can be categorized into: Membrane pump Rotary pump Micro gear pump Diffuser pump

4. Pump chamber

5. Valves

6. Check valve-example

7. Fixed geometry valve pump

8. Membrane Pump Membrane Pump often consists of two check valves and a chamber with moveable membrane. By some mechanisms, membrane can be actuated to change the volume of chamber. Because the check valve can be opened only in one direction, for each circle, some fluid will be moved from inlet to outlet.

9. Electrostatic Membrane Pump R. Zengerle et. al., MEMS’95 Goodness: Low power, good control of actuation and short response time. Weakness: High actuation voltage, small stroke.

10. Pieozelectric Membrane Pump V. Lintel et al., Sensors and Actuators A, 1988, 15:p. 153-167 Goodness: Large actuation force, and short response time. Weakness: Low working frequency, small stroke.

11. Lammerink, 1993; Lammerink, 1996 Thermopneumatic Membrane Pump Goodness: Large actuation force, low operating voltage. Weakness: Low driving frequency

12. Suction StatePumping State W.L., Benard, et. al., “A Titanium-Nickel Shape-Memory Alloy Actuated Micropump”, Proceedings of Transducers’97, vol. 1, pp.361-364 Shape Memory Alloy Driven Membrane Pump Goodness: Large pumping rate, high working pressure. Weakness: Low driving frequency, low energy efficiency

13. Centrifugal pump- rotary pump Magnetically driven Magnetic stator and central pin are permalloy Rotors were separately made and assembled into pump by hand (50 microns tall, 500 microns diameter). Problems are the complex fabrication process and reliability. C.H. Ahn and M.G. Allen, “Fluid Micropumps Based on Rotary Magnetic Actuators”, MEMS’s 95, 1995, pp. 408-412

14. Micro gear pump

15. Diffuser Pump inlet outlet Diffuser actionNozzle action Q1Q1 Q2Q2 Supplying Mode: |Q 1 |>|Q 2 | Volume increasing inletoutlet Diffuser actionNozzle action Q1Q1 Q2Q2 Pumping Mode: |Q 1 |<|Q 2 | Volume decreasing Difference between diffuser pump and membrane pump is that diffuser pump has no check valves. Instead, two diffusers are introduced. Diffuser is a channel with a increasing cross –sectional area. When fluid flows in one way or the other, it will encounter different flow resistances caused by the diffuser.

16. Except the difference between diffusers and valves, diffuser pump is similar with membrane pump. Many mechanisms can be used to drive a diffuser pump. Goodness: simple fabrication, free of valve fatigue. Weakness: sensitive to bubbles, low operating pressure Stemme et al., 1993, Diffuser Pump

17. Non-Mechanical Pump Without movable parts, non-mechanical pump is often much simpler than mechanical pump. Non-mechanical pump includes: Electric field mediated pump Bubble pump Other pumps

18. Electric field mediated pump

19. Electric-osmotic pump

20. Electric-osmotic pump-example

21. Static EHD pump

22. EHD pump-example

23. EHD Pump

24. EHD pump uses applied electric field to induce and drag charges in fluid. Goodness: no moving parts, very simple fabrication process Weakness: unsuitable for conductive fluid

25. EHD PUMP-example

26. A Planar EHD Pump + - flow positive ion + - + - + - flow Si-Hong Ahn, Yong-Kweon Kim, “Fabrication and experiment of a planar micro ion drag pump,” Sensors and Actuators A70 (1998) 1-5

27. Design of EHD Pump 1.Build the electrodes and channel on the same wafer. 2.Electrodes go across the sidewall, resulting in a higher efficiency.

28. Two Successive Pumping Photos Fluid

29. Simplest Pump: Bubble Pump T.K. Jun and C.-K. kim, J. Appl. Phys., Vol. 83, No. 11, 1998 Goodness: simple Weakness: low flow rate, and fluid will be overheated near the heater.

30. Bubble Pump T.K. Jun and C.-K. kim, J. Appl. Phys., Vol. 83, No. 11, 1998

31. Magnetic Pump

32. Magnetic Pump-example

33. Ultrasonic pump

34. Acoustic pump-example

35. Pump by interfacial tension

36. Interfacial tension pump- Example