Microfluidics and Nanofluidics
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Transcript of Microfluidics and Nanofluidics
MICROFLUIDICS and Nanofluidics
Presented bySaakre ManjeshManglam Arya
Introduction Fluid is a substance that continually flows under an
applied shear stress
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
What is a micro-fluidic system?
• A system manipulating fluids in channels having cross section dimension on less than 100 micro-meters– Smallest micro-channel: Nano-tube
Micro-channels Nano-tubes
Microfluidics
A microfluidic channel is about thesame width as a human hair, 70 μm
The objectives of micro-fluidic systems
• Micro-Total-Analysis-Systems (mTAS)– One system to provide all of
the possible required analyses for a given type problem
– All processing steps are performed on the chip
– No user interaction required except for initialization
• Lab-on-a-chip• Micro-fluidics in nature
– Alveoli (Lung bubbles)
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
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
Basic PropertiesTypes of fluids:• Newtonian fluids• Non-Newtonian fluids
Types of fluid flow:• Laminar• Turbulent
Newtonian FluidsLinear relationship between stress and strain, i.e. viscosity is independent of stress and velocity
Rate of shearing strain, dv/dy
Non-Newtonian Fluids• Non-linear relationship between shear stress and shear strain• Examples: paint, blood, ketchup, cornstarch solution
Viscosity
• Viscosity is a measure of internal friction (resistance) to flow
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
Laminar and Turbulent Flow
Reynolds number• Measure of flow turbulence• Used to help predict similar flow patterns in different
fluid flow situations. • Re < 2000 for laminar• Due to small dimensions• Re < 1 in microfluidic systems
Couette Flow (Laminar)Couette flow:• One of the plates moves parallel to the other• Steady flow between plates• No-slip condition applies
• Gives the pressure drop in an incompressible and newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant section.
• Pressure-driven flow• No-slip condition( A solid boundary, the fluid will have zero
velocity relative to boundary) applies
Poiseuille Flow (Laminar)
Diffusion• Diffusion is the transport of particles from a
region of higher concentration to one of lower concentration by random motion.
Surface Tension• Surface tension is a property of cohesion (the attraction of
molecules to like molecules)• 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
Wettability-degree of wetting • wettability is determined by a force balance between adhesive
and cohesive forces.• Adhesion vs. cohesion• Contact angles are a way to measure liquid-surface
interactions
Hydrophobic Hydrophilic
Surface energy
Sample Loading And Injection
SubatmosphericPressure Chamber
Electro-OsmoticPump
Electro-PneumaticDistributor
Small Volume Transport
MicrofluidicDevices
Micro-scale Handling System
Components of Microfludic Device
A microfluidic system for DNA separation
Allow to characterize DNA Fragments with excellent Resolution, and in a small time
DNA micrototal analysis systems (mTAS)have been made through the integration of different processes, such as PCR, separation and detection on a microscale.
Entropy recoiling Entropy trap
Continuous flow microfluidicsDroplet based Microfluidics Digital microfluidicsDNA chips (microarrays) Molecular biology Evolutionary biologyCell behaviorCellular biophysics Optics Acoustic droplet ejection (ADE)Fuel cells A tool for cell biological research Future Directions
Key application areas
Nanofluidics Study of the behavior, manipulation, and control of fluids that are
confined to structures of nanometer
Nanofluids are suspensions of nanoparticles in a base fluid, typically water
Emphasis is put on the very diverse background of nanofluidics in biology, chemistry, physics and engineering and the valuable knowledge available in these disciplines
Classical disciplines related to Nanofluidics and some of the relevant subjects studied
Significant reduction in sample volumes required for analyses
Enables experiments to be carried out that take advantage of laminar flow conditions
High surface to volume ratios
Low concentrations, molecular confinement, and low heat capacity
Advantages of nanofluidics
Manofluidics V/S NanofluidicsMicrofluidics Nano fluidics
Size- micrometer Size- Nanometer
Low Density high Density
LowSurface area to volume ratio
HighSurface area to volume ratio
Low thermal conductivity High thermal conductivity
High particle clogging and sedimentation
Low particle clogging and sedimentation
Stability- Comparatively less Stability- High
Nanoscale forces• Forces will govern the behaviour of the molecules or particles in
nanostructures
• Give rise both to equilibrium phenomena, like differences in ionic distribution, or kinetic phenomena, like (macroscopic) viscosity
• In the 1940s, Derjaguin,Verwey, Landau and Overbeek developed the DLVO theory
• Two major forces acting in the nanometre range between surfaces, namely, electrostatic forces and van der Waals forces
• Very successful in providing the theoretical framework for observed behaviour of colloid interaction and stability
• Electrostatic forces act as far as the electrical double layer extends, which is typically from 1 nm to 100 nm
• depending on the electrolyte concentration, and are either repulsive or attractive
• van der Waals forces predominantly act at distances smaller than 2 nm and are always attractive
• In 1954, Derjaguin devised a surface forces apparatus (SFA) to measure the forces acting at nano scale
• Capillary force originates in the adhesion between the liquid and the solid surface molecules, and the cohesion between the liquid molecules
• Atomic force microscopy (AFM) has recently become the most outstanding method for measuring surface forces
Cont……
Phanomena in nanofluidics
• Surface-energy-related phenomena• Shear-related phenomena• Electrical double-layer-related phenomena• Size-related phenomena• Entropy-related phenomena• Molecular-structure-related phenomena
Application• Transport Phenomena• Chemical Analysis• Study of Gene Expression• Water Purification
Transport Phenomena
Chemical Analysis Add functionality for sample manipulations in analytical chemistry, such as
sample injections, separation, purifications, and preconcentration for quantitative and qualitative identification
NCAMs functioning as controllable molecular gates can mediate digital transfer of fluid from one microfluidic channel to another
This capability has consequently found use in a miniaturized lead sensor that uses DNAzyme and for preparative post-separationmprocessing for mass limited samples
Nano Capillary Array Membrane
One system to provide all of the possible required analyses for a given type of problem
All processing steps are performed on the “chip”
No user interaction required except for initialization
High throughput screening (HTS) and diagnostics are two major applications for Lab-on-a-chip
Partitioning of functions between disposable and instrument is very different for HTS and Molecular Diagnostics
Lab-on-chip
Gene Expression Studies• Nanofluidic system to monitor gene expression continually, a
so-called dynamic study. • Altering the genes to express fluorescent proteins and exposing
the cells to different conditions • Measure the effects on gene expression as a change in
fluorescence
Problems•Detectability
concern chemical or physical analysis detection will become very problematic when low concentrations are present
together with small detection volumes
•Fouling and stability
Thank you…..