Introduction to Microfluidics: Basics and Applications

1 2002 IBM Corporation Micro & Nanobioengineering Lab Biomedical Engineering Department McGill University | McGill, Nov 2005 Introduction to Microfluidics: Basics and Applications Kate Turner Hands-on Workshop in Micro and Nanobiotechnology 4th March 2013 Optional slide number: 10pt Arial Bold, white 2 What is microfluidics? Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 3 What is microfluidics?

2 Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 4 Microfluidics Fluidics: handling of liquids and/or gases Micro: has at least one of the following features: Small volumes Small size Low energy consumption Use of special phenomena (we ll talk more about this later) . A microfluidic channel is about the same width as a human hair, 70 m Optional slide number: 10pt Arial Bold, white 5 What is microfluidics?

3 Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white Advantages of Microfluidics Low sample and reagent consumption; fluid volumes ( l; nl; pl; fl) Small physical and economic footprint Parallelization and high throughput experimentation Unique physical phenomena: use of effects in the micro-domain: Laminar flow Capillary forces Diffusion.

4 6 Lee et al. (2007). Biotech. Bioeng. 97: 1340-6. Optional slide number: 10pt Arial Bold, white 7 Right: Quake lab group, Stanford, Left: Juncker lab group, McGill, Advantages of Microfluidics Low sample and reagent consumption; fluid volumes ( l; nl; pl; fl) Small physical and economic footprint Optional slide number: 10pt Arial Bold, white 8 Advantages of Microfluidics: Lab on a Chip Parallelization and high throughput experimentation Optional slide number: 10pt Arial Bold, white 9 What is microfluidics? Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 10 Fluid Mechanics Law: Conservation of mass Law: Conservation of momentum Assumption: Incompressibility Assumption: No-slip boundary condition, velocity of the fluid flow at a surface is zero Optional slide number.

5 10pt Arial Bold, white No-slip Boundary Condition 11 Optional slide number: 10pt Arial Bold, white 12 Basic Properties Types of fluids: Newtonian fluids Non-Newtonian fluids Types of fluid flow: Laminar Turbulent Optional slide number: 10pt Arial Bold, white Shearing stress, Rate of shearing strain, dv/dy 13 Newtonian Fluids Linear relationship between stress and strain, viscosity is independent of stress and velocity v + dv vOptional slide number: 10pt Arial Bold, white Substance Viscosity (mPa s) Air Acetone Water Mercury Olive oil 80 Honey 2,000 10,000 Viscosity 14 Viscosity is a measure of internal friction (resistance) to flow Optional slide number: 10pt Arial Bold, white Non-Newtonian Fluids 15 Non-linear relationship between shear stress and shear strain Examples: paint, blood, ketchup, cornstarch solution Rate of shearing strain, dv/dy Shearing stress, Newtonian Non-Newtonian shear thickening Non-Newtonian shear thinning Optional slide number.

6 10pt Arial Bold, white 16 Laminar and Turbulent Flow Laminar flow: Fluid particles move along smooth paths in layers Most of energy losses are due to viscous effects Viscous forces are the key players and inertial forces are negligible Turbulent flow: An unsteady flow where fluid particles move along irregular paths Inertial forces are the key players and viscous forces are negligible Reynolds number: Measure of flow turbulence Re < 2000 for laminar Due to small dimensions Re < 1 in microfluidic systems where : fluid density A: cross-sectional v: fluid velocity area of channel L: characteristic length P: wetted perimeter : viscosity Optional slide number: 10pt Arial Bold, white Laminar and Turbulent Flow 17 Optional slide number: 10pt Arial Bold, white 18 Couette Flow (Laminar) Couette flow.

7 One of the plates moves parallel to the other Steady flow between plates No-slip condition applies Optional slide number: 10pt Arial Bold, white 19 Poiseuille Flow (Laminar) Poiseuille flow: Pressure-driven flow No-slip condition applies Optional slide number: 10pt Arial Bold, white 20 What is microfluidics? Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 21 What is microfluidics?

8 Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 22 Laminar Flow Right: P. Yager et al. (2006). Nature 442: 412-18. Left: Kenis et al. (1999). Science 285: 83-5. Optional slide number: 10pt Arial Bold, white Diffusion Diffusion is the transport of particles from a region of higher concentration to one of lower concentration by random motion.

9 X: diffusion length D: diffusion constant t: time 23 For an antibody, D 40 m2 s-1 For urea, D 1400 m2 s-1 For X = 100 m, the time becomes: Antibody: 125 s; Urea: s Optional slide number: 10pt Arial Bold, white Diffusion and Mixing University of Hertfordshire, STRI, 24 Direction of Flow Optional slide number: 10pt Arial Bold, white Generating Biochemical Gradients Jeon et al. (2000). Langmuir 16: 8311 16. 25 Optional slide number: 10pt Arial Bold, white Generating Biochemical Gradients N. L. Jeon et al., Langmuir, 2000, 16, 8311 16. 26 Optional slide number: 10pt Arial Bold, white 27 What is microfluidics?

10 Why microfluidics? Basics of fluid mechanics Special phenomena associated with the micro-scale Laminar flow Diffusion and mixing Capillary phenomena Surface energy Microfluidics and lab-on-a-chip devices Outline Optional slide number: 10pt Arial Bold, white 28 Capillary Phenomenon and Liquid Transport Optional slide number: 10pt Arial Bold, white 29 Capillary Phenomenon and Liquid Transport Optional slide number: 10pt Arial Bold, white 30 Capillary Phenomenon r h Pressure of the liquid column: Capillary pressure: Height of liquid column.