Introduction to Microfluidics - KATE.pptx - McGill University

Micro & Nanobioengineering Lab
Biomedical Engineering Department
McGill University
Introduction to Microfluidics:
Basics and Applications
Kate Turner
Hands-on Workshop in Micro and Nanobiotechnology
4 th March 2013
katherine.turner2@mail.mcgill.ca
| McGill, Nov 2005
© 2002 IBM Corporation
wikisites.mcgill.ca/djgroup

Optional slide number:
Outline
§ 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
2

Optional slide number:
Outline
§ 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
3

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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 µm
4

Optional slide number:
Outline
§ 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
5

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Advantages of Microfluidics
§ Low sample and reagent consumption; fluid volumes (µl; 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
.
P.J. Lee et al. (2007).
Biotech. Bioeng. 97: 1340-6.
6

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Advantages of Microfluidics
§ Low sample and reagent consumption; fluid volumes (µl; nl; pl; fl)
§ Small physical and economic footprint
7
Right: Quake lab group, Stanford, http://thebigone.stanford.edu/
Left: Juncker lab group, McGill, http://wikisites.mcgill.ca/djgroup/

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Advantages of Microfluidics: Lab on a Chip
§ Parallelization and high throughput experimentation
8

Optional slide number:
Outline
§ 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
9

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Fluid Mechanics
§ Law: Conservation of mass
§ Law: Conservation of
momentum
§ Assumption: Incompressibility
§ Assumption: No-slip boundary
condition, i.e. velocity of the
fluid flow at a surface is zero
10

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No-slip Boundary Condition
11

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Basic Properties
§ Types of fluids:
§ Newtonian fluids
§ Non-Newtonian fluids
§ Types of fluid flow:
§ Laminar
§ Turbulent
12

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Newtonian Fluids
§ Linear relationship between stress and strain, i.e. viscosity is
independent of stress and velocity
v + dv
v
Shearing stress, τ
Rate of shearing strain, dv/dy
13

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Viscosity
§ Viscosity is a measure of internal friction (resistance) to flow
Substance Viscosity (mPa·s)
Air 0.017
Acetone 0.3
Water 0.9
Mercury 1.5
Olive oil 80
Honey 2,000 – 10,000
14

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Non-Newtonian Fluids
§ Non-linear relationship between shear stress and shear strain
§ Examples: paint, blood, ketchup, cornstarch solution
Non-Newtonian
shear thickening
Newtonian
Shearing stress, τ
Non-Newtonian
shear thinning
Rate of shearing strain, dv/dy
15

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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
16

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Laminar and Turbulent Flow
17

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Couette Flow (Laminar)
§ Couette flow:
§ One of the plates moves parallel to the other
§ Steady flow between plates
§ No-slip condition applies
18

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Poiseuille Flow (Laminar)
§ Poiseuille flow:
§ Pressure-driven flow
§ No-slip condition applies
19

Optional slide number:
Outline
§ 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
20

Optional slide number:
Outline
§ 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
21

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Laminar Flow
Right: P. Yager et al. (2006). Nature 442:
412-18.
Left: P.J.A. Kenis et al. (1999). Science
285: 83-5.
22

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Diffusion
Diffusion is the transport of particles from a region of higher
concentration to one of lower concentration by random motion.
X: diffusion length
D: diffusion constant
t: time
For an antibody, D ≈ 40 µm 2 s -1
For urea, D ≈ 1400 µm 2 s -1
For X = 100 µm, the time becomes:
Antibody: 125 s; Urea: 3.6 s
23

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Diffusion and Mixing
Direction
of Flow
24
University of Hertfordshire, STRI, http://www.herts.ac.uk/research/stri.html

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Generating Biochemical Gradients
N.L. Jeon et al. (2000). Langmuir 16: 8311–16.
25

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Generating Biochemical Gradients
26
N. L. Jeon et al., Langmuir, 2000, 16, 8311–16.

Optional slide number:
Outline
§ 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
27

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Capillary Phenomenon and Liquid Transport
28

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Capillary Phenomenon and Liquid Transport
29

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Capillary Phenomenon
Pressure of the liquid column:
ΔP = ρgh
θ
r
Capillary pressure: ΔP
= −
γ : Surface tension
Height of liquid column:
θ
: Contact angle
h
=
2γ
r
2γ cosθ
ρgr
h
30

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Surface Tension
§ Surface tension is a property of cohesion (the attraction of molecules
to like molecules) Floating razor blades
§ When an interface is created, the distribution of cohesive forces is
asymmetric
§ Molecules at the surface may be pulled
on more strongly by bulk molecules
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Wettability
§ Adhesion vs. cohesion
§ Contact angles are a way to measure liquid-surface interactions
Hydrophobic
Hydrophilic
32

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Capillary Systems
33

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Capillary Systems
34

Optional slide number:
Outline
§ 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
35

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Microfluidic and Lab-on-a-Chip Devices
Microfluidic
Devices
Closed chips
Open
Chips
Continuous flow
Droplet-based
Microfluidic
probes (MFP)
Micro-arrays
External pressure
Digital microfluidics
Ink-jet printing
Capillary effect
Electrokinetic mechanisms
Electrowetting-ondielectirc
Surface acoustic
waves
Optoelectrowetting
Pin-printing
technology
Microcontact
printing
36

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Immunoassay
§ A biochemical test that measures the concentration of a
substance in a biological liquid
§ Enzyme-Linked ImmunoSorbent Assay (ELISA)
§ Sandwich assays
Immobilized capture
antibody
Captured antigen
from the sample
Fluorescently labelled
detection antibody
37

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Micromosaic Immunoassay
Immobilization
Immobilization
Capture 1
Capture 2
Recognition
Sample Loading
Reading Signal
Detection
Fluorescently-labelled
Detection Antibodies
M. Pla-Roca, D. Juncker. (2011). Biological Microarrays, Humana Press, USA.
38

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Micromosaic Immunoassay
Immobilization
Immobilization
Capture 1
Capture 2
Recognition
Sample Loading
Reading Signal
Detection
Fluorescently-labelled
Detection Antibodies
M. Pla-Roca, D. Juncker. (2011). Biological Microarrays, Humana Press, USA.
39

Optional slide number:
Micromosaic Immunoassay
Immobilization
Immobilization
Capture 1
Capture 2
Recognition
Sample Loading
Reading Signal
Detection
Fluorescently-labelled
Detection Antibodies
M. Pla-Roca, D. Juncker. (2011). Biological Microarrays, Humana Press, USA.
40

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Droplet-Based Microfluidics
A.S. Utada et al. (2005). Science 22: 537-41.
41

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Isolation/Detection of Rare Cells
S. Nagrath et al. (2007). Nature 450: 1235-39.
42

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Recapitulating Organ Function on a Chip
D. Huh et al. (2010). Science 25: 1662-68.
43

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Microfluidic Probe for Perfusion of Brain Slices
a
b
c
d
A. Queval et al. (2010). Lab Chip 10: 326-34.
Technology developed in our laboratory
44

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Thank You!
QUESTIONS
45

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Microfluidics advantages
§ Parallelization and high throughout experimentation
46
Source: The National Institute of Standards and Technology (NIST)

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Incompressible vs compressible:
Gas particles are very spread out, so
can be compressed
Liquid particles are not spread out, so
hard to be compressed
Source: The Nucleus Learning website
47

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Surface energy of various liquids
48

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Surface energy of various solids
49

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Autonomous control with hydrogels
D. J. Beebe, Nature 404, 588-590 (2000).
50

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Surface energy
water
hydrophilic
• Hydrophilic Surfaces:
“Water-­‐loving surface”
Water tries to maximize
contact with surface.
water
hydrophobic
• Hydrophobic Surfaces:
“Water-­‐fearing surface”
Water tries to minimize
contact with surface.
CONTACT ANGLE
water
superhydrophobic
• Superhydrophobic Surfaces:
Hydrophobic surface having
nano-­‐scale roughness.
0° 5° 35° 40°
100° 115°
160°
51
Plasma
Cleaned
Glass
Polyethylene
Glass Glycol
SAM
Polystyrene
PTFE
(Teflon
)
Superhydrophobic
IsotacWc
Polypropylene