AN INTRODUCTION TO MICROFLUIDICS : Lecture n°1

1. AN INTRODUCTION TO MICROFLUIDICS : Lecture n°1 Patrick TABELING, patrick.tabeling@espci.fr ESPCI, MMN, 75231 Paris 0140795153

2. Outline of Lecture 1 1 - Past and present of microfluidics 2 - Microfluidics, nanofluidics and macroscopic approach. 3 - The changes in the balances of forces that result from miniaturization.

3. SOME REFERENCES

6. Translation by Suelin CHEN Oxford University Press To appear, 20 Oct 2005 Oxford Univ Press

7. MEMS = MICRO ELECTROMECHANICHAL SYTEMS Systems whose sizes lie in the range 1 -300 microns A new situation arose in the seventies, further to the tremendous development of microelectronics : it became possible to fabricate all sorts of miniaturized objects : microcondensators, microvalves, micropumps, microresonators, microdispenser... by exploiting an important accumulation of technological knowledge, and taking advantage of the availability of sophisticated equipment.

9. This generated a substantial economical activity

10. Airbag Sensor- Analog Device 300 mm 3 mm

11. Commercial Inkjet using MEMS technology 2 mm

14. Perhaps, everything started with a talk given by R. Feynman…. There's Plenty of Room at the Bottom An Invitation to Enter a New Field of Physics R Feynman, CALTECH, Dec 1959

15. First Silicon Beams 1988 Spring Howe & Muller 1982 1982 Fan, Tai & Muller, 1988 Micro-Electro-Mechanical -System MEMS

16. Fan,Tai and Muller 1989 First micromotor (1989) Insect spinning on a micromotor

17. 100 mm

18. Craighead (Cornell)

19. HOW DO WE FABRICATE A MEMS ?

20. Si Oxydation Développement Si Si Si Si Depot de resine Ouverture et strippage masque Si Attaque par KOH Insolation Si Microfabrication of a membrane

21. Microfluidics came later, in the nineties Microfluidics = Realization and study of flows and transfers in (artificial) microsystems

22. A few milestones 1970 - 1990 : Essentially nothing (apart from the Stanford gas chromatographer) 1990 : First liquid chromatograph (Manz et al) mTAS concept (Manz, Graber, Widmer, Sens.Actuator, 1991) 1990 -1998 : First elementary microfluidic systems (micromixers, microréactors, separation systems,..) 1998-2004 : Appearance of soft lithography technology, which fostered the domain. All sorts of microfluidic systems with various levels of complexity are made, using different technologies

23. First microfluidic system : Terry (1975) (Stanford) Injection valve Canal de 1.5 m long Thermal sensor Reyes et al, Anal Chem, 74, 2623 (2002)

24. A microfluidic system for DNA separation From Agilent- Caliper Allow to characterize DNA Fragments with excellent resolution, and in a small time

25. A system which will probably have an impact in biology Les opérations élémentaires Chargement, compartimentage Mélange, purge. (Quake et al, Science 2002)

26. An elementary Lab-on-a-chip BIOSITE LAB-ON A CHIP DIAGNOSES HEART ATTACK WITHIN 10 MN

27. PERSPECTIVES OF MICROFLUIDICS

28. Microfluidics is increasingly used in an impressive number of domains - Food industry - Chemistry - Biotechnology - Oil industry - Drug discovery In these domains, microfluidic systems of various complexities are needed, and the challenge is to be able to respond to these needs. Current estimates indicate microfluidic demands will grow at a fast rate over the next 5 years, generating visible economical activity

29. One day, we’ll perhaps receive this strange watch as a birthday gift

30. It is not sure however we will be capable soon to mimick a number of natural systems The tree The spider

31. FLUIDS FLOWING IN NANOMETRIC DEVICES- NANOFLUIDICS

32. Nanofluidics 1nm 10nm 100nm 100mm 1mm 1mm 1mm 10mm Microfluidics Single molecule

33. Two admissible definitions of nanofluidics Definition 1 (engineer definition) : Nanofluidics deals with fluids flowing in systems whose Characteristic sizes range between 10 and 300 nm Definition 2 (physicist definition) : Nanofluidics deals with fluids flowing in conditions where interactions between micro and macroscopic scales play a crucial role.

34. Some notions on the ranges of influence of Intermolecular microscopic forces MOSY OF WHAT WE KNOW ON THE BEHAVIOUR OF SIMPLE LIQUIDS AT THE NANOSCALE COMES FROM THIS MACHINE (Tabor, Israelachvilii ~1980)

35. This is not the case for the Van der Waals forces between surfaces in the vacuum, whose extent lies in the nm range

36. FORCES LINKED TO THE PRESENCE OF ADSORBED LAYERS

37. Debye layers may have sizes comparable to Submicrometric channels.

38. In the presence of an electrolyte, Debye layers develop DEBYE-HUCKEL layers - typically 100 nm up to 1mm thick in pure water

39. Mean free path in gases Thermal capillarity length Nanofluidics is a host of Many novel phenomena, Involving interactions between Microscopic and macroscopic scales Bubble nucleation barrier Debye layer thickness Fluctuation forces range VdW force range Nanofluidics 1nm 10nm 100nm 1kmm 1mm 10mm 100mm Microfluidics Single Molecule studies

40. BREAKUP OF A NANOJET ( NUMERICAL EXPERIMENTS) M. Moseler, U. LandmanScience, 289, 5482, 1165 - 1169 (2000)

41. Nanojets do not behave like ordinary jets Microjet Nanojet The reason is that capillary thermal scale matters : l=(kT/g)1/2

42. Working with negative pressures becomes feasible

44. Macroscopic approach generally assumes that the interfaces are infinitely thin Boundary conditions Laplace law

45. Speculating about possible effects in nanochannels Laminar flow are not parabolic; they probe the nature of the surfaces exposed to the fluid Free interfaces behave in a strange way in nanochannels Hydrodynamic instabilities behave differently Fabricate superfluid hydrogen.

48. 500 nm

49. Nanofluidics is not just an exotic subject : we already use nanofabricated nanochannels in a number of applications Separation of long strands of DNS by usine nanopillars (Baba et al, Univ. Tokyo)

50. A broad prospective on nanofluidics (from A. Van den Berg)