1. A Microfluidic System for Controlling Reaction Networks In Time Presented By Wenjia Pan

2. A Microfluidic System for Controlling Reaction Networks It allows to control –When each reaction begins –For how long each reaction evolves –When each reaction is analyzed or quenched

3. A Microfluidic System for Controlling Reaction Networks Why microscopic chemical reactions? –Traditionally, macroscopic Labs, using test tubes and etc. –Advantages to perform chemical reactions in microscopic: To manipulate, process and analyze molecular reaction on the micrometer to nanometre scale

4. A Microfluidic System for Controlling Reaction Networks Applications –Parallel combinational chemical reactions No impurity No cross-contamination –nanomaterial synthesis Allow user to synthesize species of specific yet variable characteristics. –Integrated microfluidic bioprocessor thermal cycling sample purification capillary electrophoresis http://www.nature.com/nature/jour nal/v442/n7101/full/nature0506 2.html

5. Linear transform: t = d/u –t: time used for reaction [s] –d: distance traveled [m] – u: flow rate [m/s] Setup: –Initial: d = 0  t = 0 –At constant velocity: t = d/u A Microfluidic System for Controlling Reaction Networks

6. 3 Types of behavior in fluid dynamics –Laminar flow (Re < 2100) –Transition flow (2100 < Re < 3000) –Turbulent flow (Re > 3000) Microfluidic system: laminar flow Re: Reynolds number

7. Reynolds Number –Vs: the velocity of the flow [m/s] –P : the density [kg/m 3 ] –L : the diameter of the capillary [m] – : the viscosity of the fluid [kg/ms] – V : the kinetic fluid viscosity – A Microfluidic System for Controlling Reaction Networks

8. Reynolds number –To quantify the relative importance of the inertial forces and the viscous forces –To identify if it is laminar/turbulent flow http://www.daviddarling.info/encyclopedia/L/laminar_flow.html

9. A Microfluidic System for Controlling Reaction Networks From left top corner, clockwise: Re = 1.54,(9.6, 13.1, 26), 105 http://www.media.mit.edu/physics/pedagogy/nmm/student/95/aries/mas864/obstacles.html

10. A Microfluidic System for Controlling Reaction Networks A comparison: –Top: Re = 150 –Bottom: Re =105 http://www.media.mit.edu/p hysics/pedagogy/nmm/s tudent/95/aries/mas864/ obstacles.html

11. A Microfluidic System for Controlling Reaction Networks Challenges –Mixing is slow d = 0 NOT => t=0 –Dispersion is large Velocity is not consistent. t = d/u is a range. ANGEWAND Edition 42(7) : 768 – 772, 2003

12. A Microfluidic System for Controlling Reaction Networks Practical model described here –Mixing is faster –Dispersion eliminated ANGEWAND Edition 42(7): 768 – 772, 2003

13. A Microfluidic System for Controlling Reaction Networks Methods described –For forming plugs of multiple solutions of reagents –For using chaotic advection to achieve rapid mixing –For splitting and merging these plugs in order to create microfluidic networks

14. A Microfluidic System for Controlling Reaction Networks Plugs of solutions of reagent A and B –A, B: 2 laminar streams –Separating stream: inert center stream Diffusion will be slow –Water immiscible perfluorodecaline (PFD) Inert Immiscible with water Organic solvents Does not swell PDMS http://en.wikipedia.org/wiki/Polydimethylsiloxane

15. A Microfluidic System for Controlling Reaction Networks Plug Forming: –Mixes left and right, NOT top and the bottom –Laminar flow preserved

16. A Microfluidic System for Controlling Reaction Networks Chaotic advection: rapid mixing –Fluid cavity experiments Simultaneous motion Time-periodic, alternating motion ANGEWAND Edition 42(7) : 768 – 772, 2003

17. A Microfluidic System for Controlling Reaction Networks Microfluidic system –Similar situation –Different frame of reference Flow cavity experiment: reference = the fluid Microfluidic system: reference = walls ANGEWAND Edition 42(7) : 768 – 772, 2003

18. A Microfluidic System for Controlling Reaction Networks ANGEWAND Edition 42(7) : 768 – 772, 2003

19. A Microfluidic System for Controlling Reaction Networks ANGEWAND Edition 42(7): 768 – 772, 2003

20. A Microfluidic System for Controlling Reaction Networks Splitting and merging –Merging: Merging channel: wide main channel Small droplets move more slowly Driven with pressure ANGEWAND Edition 42(7) : 768 – 772, 2003

21. A Microfluidic System for Controlling Reaction Networks Splitting –Constricting the channel at the branching points –Be subjected to pressure gradients ANGEWAND Edition 42(7) : 768 – 772, 2003

22. A Microfluidic System for Controlling Reaction Networks Conclusion –Advantages Planar Trivia to fabricate Disposable plastic chip Available equipment –Applications High-throughout screening Combinational synthesis Analysis diagnostics

23. A Microfluidic System for Controlling Reaction Networks Summary –Strengths: Controllable and rapid mixing Able to build complex microfluidic networks –Weakness: Hard to extract the vast amount of information produced in a complex networks http://www.nature.com/nature/journal/v442/n7101/fig_tab/nature05062_F6.html