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Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography

Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography. Unger et al. (Quake group, CALTECH) Science, 2000. EECE 491C. How complex and how big?. ENIAC, first large scale electronic and digital computer 30 tons, 19,000 vacuum tubes, 200 kW Towards integrated circuits

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Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography

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  1. Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography Unger et al. (Quake group, CALTECH) Science, 2000 EECE 491C

  2. How complex and how big? • ENIAC, first large scale electronic and digital computer • 30 tons, 19,000 vacuum tubes, 200 kW • Towards integrated circuits • Large Scale Integrated Circuits (LSI) Courtesy www-ivs.cs.uni-magdeburg.de EECE 491C

  3. Biochemical Laboratories • Expensive Reagents • Small amounts of samples available • High levels of multiplicity required • Portability • Equipment Costs • Level of training Courtesy www.nature.com/ vol 442- Yager Courtesy www.stanford.edu/group/crg EECE 491C

  4. Microelectromecanichal structures (MEMS) • Bulk micromachining: • Single-Crystal silicon lithographically patterned then etched • Stress between layers • Surface Micromachining: • Additive method • Patterning. Max thickness 20 um • Limited materials • Stiff materials = hard to make smaller features Courtesy http://dei-s1.dei.uminho.pt Courtesy http://www.aero.org EECE 491C

  5. Soft Lithography • With only one layer it is difficult to create active devices or moving parts EECE 491C

  6. Multilayer Soft Lithography • Can bond different layers of elastomer • Elastomer: silicon rubber, 2 component, polymer and cross-linker • Each layer has excess of one of the 2 • Upon contact layers form hermetic seal • Can easily create multilayer devices • Can create electro-magnetic devices by doping EECE 491C

  7. Valves • Fluid is introduced with pins • Can accept up to 300 kPa without leakage • Typical channel size X • Membrane between layers • Response time ~1ms • 1mN of force (100kPa) • Pneumatic activation: dense packing possible EECE 491C

  8. Valves and Pressure • Flow Layer: biological assay, fluid manipulation • Control Layer: actuate valves • Valve opening controlled by fluorescence EECE 491C

  9. From Valves to Pumps • A - on/off valve 200x100 • B - on/off valve 30x50 • C - peristaltic pump • D - grid of valves • E - switching valve • F - section of 7 layer device • Scale bars: 200 um EECE 491C

  10. Elastomeric Peristaltic Pump • 50 kPa of applied pressure • Channels 100 um wide and 10 um high • Durable • E coli showed 94% survival rate EECE 491C

  11. Valves and Pumps • Durable • Low dead volumes • Complete sealing even in presence of particulates • Easy to produce • Cheap • Rapid prototyping • Multiple layers possible • Transparent • Biocompatible • Countless applications Courtesy nature.com vol 442 Whitesides, Quake EECE 491C

  12. Valves and Pumps Courtesy Carl Hansen EECE 491C

  13. Valves and Pumps Courtesy Carl Hansen EECE 491C

  14. Microfluidic Large-Scale Integration Thorsen et al. (Quake group, CALTECH) Science, 2002 EECE 491C

  15. The Multiplexor • Microvalves are scalable and leakproof • Can now have multiplexed addressing and control • Binary tree • fluid channels • control channels • Only 20 control for 1024 flow channels EECE 491C

  16. Memory Storage Design • 1000 individually addressable 250pL chambers • Microfluidic memory storage device • Similar to Random Access Memory (RAM) EECE 491C

  17. Memory Storage • Row Multiplexor: fluid trafficking (RAM word line) refreshes compartments within a row • Column Multiplexor: controls vertical input-output valves for specific central compartments • Display Monitor EECE 491C

  18. Microfluidic Comparator Chip • Allows mixing of 2 separate reagents, unloading • 256 rxn chambers EECE 491C

  19. The Experiment • Ecoli in one compartment • Amplex red (AR) in the other column • Compartments opened • CCP converts AR to resorufin • Control using GFP EECE 491C

  20. Controls • Heterogeneous mixture of E. coli expressing CCP or eGFP • Amplified signal dependent only on number of CCP expressing cells in individual chambers EECE 491C

  21. Conclusions • Ability to integrate and control many fluidic elements • Selective manipulation and recovery • Scalable devices • Can envision chemical and biochemical analysis • High throughput screening applications, liquid display technology • Creation of microfluidic LSI • Rapid, simple fabrication • Disadvantages of PDMS EECE 491C

  22. Critique Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography • Well presented, ground-breaking • Limited discussion of other techniques available • Weak Biological experiments or applications • Limited discussion of flaws of the materials used • Certain figures are not very detailed • Would have been interesting to see a picture of the entire device EECE 491C

  23. Critique Microfluidic Large Scale Integration • Well presented, ground-breaking, great intro • Explanatory analogies • Weak Biological experiments-weaker ending • More thorough discussion of flaws of the materials used • One figure mislabeled • Great device pictures EECE 491C

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