nanotechnology-in-mechanical-engineering.ppt

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1. 1
Nanotechnology
in
Mechanical Engineering

2. 2
Outline of the Presentation
Lecture
In-class group activities
Video Clips
Homework

3. 3
Course Outline
Lecture -I
Introduction to Nano-
Technology in Engineering
Basic concepts
Length and time scales
Nano-structured materials
-Nanocomposites
-Nanotubes and nanowire
Applications and Examples
Lecture –II
Nano-Mechanics
Nanoscale Thermal
and FlowPhenomena
Experimental
Techniques
Modeling and
Simulation

4. 4
Lecture Topics
We will address some of the key issues of nano-
technology in Mechanical Engineering.
Some of the topics that will be addressed are
nano-structured materials; nanoparticles and
nanofluids, nanodevices and sensors, and
applications.

5. 5
Major Topics in Mechanical Engineering
Mechanics:
Statics :Deals with forces, Moments,
equilibrium of a stationary body
Dynamics:Deals with body in
motion -velocity, acceleration,
torque, momentum, angular
momentum.
Structure and properties of
material(Including strengths)
Thermodynamics, power
generation, alternate energy
(power plants, solar, wind,
geothermal, engines)
Design of machines and
structures
Dynamics system, sensors
and controls
Robotics
Computer-Aided Design
(CAD/CAM)
Computational Fluid
Dynamics (CFD) and
Finite Element Method
Fabrication and
Manufacturing processes

6. 6
x = 10 mm x = 250 mm x = 500 mm x = 750mm x = 1000
mm
DC power Supply
(-) (+)
Cathode
Electrode
Anode
Electrode
Electron flow
Electrolyte membrane 
H

e2
2H


Bipolar Plates
MEAs
Diesel Engine Simulation Model
Fuel Cell Design
and Development
No slip
condition
Slip Conditions
Flow in micro channel

7. 7
Length Scales in Sciences and
Mechanics 10
10

8
10
 6
10

Quantum
Mechanics
s
Molecular
Mechanics
Nano-
mechanics 3
10


Micro-
mechanics 0
10

Macro-
Mechanics

Regimes of Mechanics
Length Scales (m)
Quantum Mechanics:
Deals with atoms -
Molecular Mechanics:
Molecular Networks -
Nanomechanics:
Nano-Materials -
Micromechanics:
Macro-mechanic:
Continuum
substance

8. 8
Quantum and Molecular Mechanics
All substances are composed molecules or atoms in
random motion.
For a system consisting of cube of 25-mm on each side
and containing gaswith atoms.
To specify the position of each molecule, we need to
three co-ordinates and three component velocities
So, in order to describe the behavior of this system
form atomic view point, we need to deal with at least
equations.
This is quite a computational task even with the most
powerful (massively parallel multiple processors)
computer available today.
There are two approaches to handle this situations:
Microscopicor Macroscopicmodel20
106 20
10

9. 9
Microscopic Vs Macroscopic
Approach -1:Microscopic viewpointbased on
kinetic theory and statistical mechanics
On the basis of statistical considerations and probability theory,
we deal with average values of all atoms or molecules and in
connection with a model of the atom.
Approach –II Macroscopic view point
Consider gross or average behavior of a number of molecules
that can be handled based on the continuum assumption.
We mainly deal with time averaged influence of many molecules.
These macroscopic or average effects can be perceived by our
senses and measured by instruments.
This leads to our treatment of substance as an infinitely divisible
substance or continuum.

10. 10
Breakdown of Continuum Model
To show the limit of continuum or macroscopic model, let us
consider the concept of density:
Density is defined as the mass
per unit volume and expressed as
Where is the smallest volume for which substance can be
assumed as continuum.
Volume smaller than this will lead to the fact that mass is not
uniformly distributed, but rather concentrated in particles as
molecules, atoms, electrons etc.
Figure shows such variation in density as volume decreases below
the continuum limit.V
m
lim
/
VV




/
V

V

11. 11
Macroscopic Properties and
Measurement
Pressure
Pressure is defined as the
average normal-component
of force per unit area and
expressed as
Where is the smallest
volume for which substance can
be assumed as continuum. A
F
P
n
/
AA
lim



 /
A A
F
nF

P
Pressure
Gauge
Gas
Tank
Pressure
Measurement
For a pressure gauge, it is the
average force (rate of change of
momentum) exerted by the
randomly moving atoms or
molecules over the sensor’s area.
Unit: Pascal (Pa) or 2
m
N

12. 12
Introduction-Nanotechnology
Nanoscale uses “nanometer” as the basic unit of
measurement and it represents a billionth of a
meteror one billionth of a part.
Nanotechnology deals with nanosized particles
and devices
One-nmis about 3 to 5 atoms wide. This is very
tiny when compared normal sizes encounter day-
to-day.
-For example this is 1/1000
th
the width of human
hair.

13. 13
Any physical substance or device with structural
dimensions below 100 nm is called nanomaterial
or nano-device.
Nanotechnology rests on the technology that
involves fabrication of material, devices and
systems through direct control of matterat
nanometer length scaleor less than 100 nm.

14. 14
Nanoparticles can be defined as building blocks of
nanomaterials and nanotechnology.
Nanoparticles include nanotubes, nanofibers, fullerenes,
dendrimers, nanowiresand may be made of ceramics,
metal, nonmetal, metal oxide, organic or inorganic.
At this small scalelevel, the physical, chemical and
biological properties of materials differsignificantly from
the fundamental properties at bulk level.
Many forces or effectssuch inter-molecular forces,
surface tension, electromagnetic, electrostatic, capillary
becomes significantly more dominant than gravity.
Nanomaterial can be physically and chemically
manipulatedto alter the properties, and these properties
can be measured using nanoscale sensors and gages.

15. 15
A structure of the size of an atom represents one of the
fundamental limit.
Fabricating or making anything smaller require
manipulation in atomic or molecular level and that is
like changing one chemical form to other.
Scientist and engineers have just started developing new
techniques for making nanostructures.
Nanoscience
Nanofabrication Nanotechnology
The nanoscience is matured.
The age of nanofabrication is
here.
The age of nanotechnology -
that is the practical use of
nanostructure has just started.

16. 16
Nanotechnology in Mechanical
Engineering
New Basic
Concepts
Nano-
Mechanics
Nano-Scale
Heat Transfer
Nano-fluidics
Applications

17. 17
Applications
Structural materials
Nano devices and sensors
Coolants and heat spreaders
Lubrication
Engine emission reduction
Fuel cell –nanoporous
electrode/membranes/nanocatalyst
Hydrogen storage medium
Sustainable energy generation -Photovoltaic cells for
power conversion
Biological systems and biomedicine

18. 18
Basic Concepts
Energy Carriers
Phonon:Quantized lattice vibration energy with wave
nature of propagation
-dominant in crystalline material
Free Electrons:
-dominant in metals
Photon:Quantized electromagnetic energy with wave
nature of propagation
-energy carrier of radiative energy

19. 19
Length Scales
Two regimes:
I. Classical microscale size-effect domain –Useful for
microscale heat transfer in micron-size environment.
c
L 
m
Where
characteristic device dimension
mean free path length of the substance)1(O
m
cL


II. Quantum nanoscale size-effect domain –
More relevant to nanoscale heat transfer
Where
characteristic wave length of the electrons
or phonons )1(O
c
c
L

 
c

20. 20
This length scale will provide the guidelines for
analysis method-both theoretical and
experimental methods:
classical microscale domain or nanoscale
size-effect domain.

21. 21
Flow in Nano-channels
The Navier –Stokes (N-S) equation of continuum model fails when the
gradients of macroscopic variables become so steep that the length scale is of
the order of average distance traveled by the molecules between collision.
Knudsen number( ) is typical parameter used to classify the length scale
and flow regimes:L
Kn


Kn < 0.01: Continuum approach with traditional Navier-Stokes
and no-slip boundary conditions are valid.
0.01<Kn<0.1: Slip flow regime and N-S with slip boundary
conditions are applicable
0.1<Kn<10: Transition regime–Continuum approach completely
breaks –Molecular Dynamic Simulation
Kn > 10 : Free molecular regime –The collision less Boltzman
equation is applicable.

22. 22
Time Scales
Relaxation timefor different collision process:
Relaxation time for phonon-electron
interaction:
Relaxation time for electron-electron
interaction:
Relaxation time for phonon-phonon
interaction: )s
11
10( O
 )s
13
10( O
 )s
13
10( O


23. 23
Nanotechnology: Modeling
Methods
Quantum Mechanics
Atomistic simulation
Molecular Mechanics/Dynamics
Nanomechanics
Nanoheat transfer and Nanofluidics

24. 24
Models for Inter-molecules Force
-Inter-molecular Potential
Model
-Inverse Power Law Model or
Point Centre of Repulsion
Model
-Hard Sphere Model
-Maxwell Model
-Lennard-Jones Potential
Model
Inter-Molecular Distance
Force
Inter-molecular
Potential Model

25. 25
Nanotools
Nanotools are required for manipulation of matter at
nanoscale or atomic level.
Certain devices which manipulate matter at atomic or
molecular level are Scanning-probe microscopes,
atomic force microscopes, atomic layer deposition
devicesand nanolithography tools.
Nanolithography means creation of nanoscale structure
by etching or printing.
Nanotools comprises of fabrication techniques, analysis
and metrology instruments, software for
nanotechnology research and development.
Softwares are utilized in nanolithography, 3-D printing,
nanofluidics and chemical vapor deposition.

26. 26
Nanoparticles and Nanomaterials
Nanoparticles:
Nanoparticles are significantly larger than individual
atoms and molecules.
Nanoparticles are not completely governed by either
quantum chemistry or by laws of classical physics.
Nanoparticles have high surface area per unit volume.
When material size is reduced the number of atoms on
the surface increases than number of atoms in the
material itself. This surface structure dominates the
properties related to it.
Nanoparticles are made from chemically stable metals,
metal oxides and carbon in different forms.

27. 27
Carbon -Nanotubes
Carbon nanotubes are hollow
cylinders made up of carbon atoms.
The diameterof carbon nanotube is
few nanometersand they can be
several millimeters in length.
Carbon nanotubes looks like rolled
tubes of graphite and their walls are
like hexagonal carbon rings and are
formed in large bundles.
Have high surface area per unit
volume
Carbon nanotubes are 100 times
stronger than steel at one-sixth of the
weight.
Carbon nanotubes have the ability to
sustain high temperature ~ 2000 C.

28. 28
Therearefourtypesofcarbon
nanotube:SingleWalledCarbon
Nanotube(SWNT),MultiWalled
Xarbonnanotube(MWNT),Fullerene
andTorus.
SWNTs are made up of single
cylindrical grapheme layer
MWNTs is made up of multiple
Grapheme layers.
SWNT possess important electric
properties which MWNT does not.
SWNT are excellent conductors, so finds
its application in miniaturizing
electronics components.

29. 29
Formed by combining two or more
nanomaterials to achieve better
properties.
Gives the best properties of each
individual nanomaterial.
Show increase in strength, modulus of
elasticity and strain in failure.
Interfacial characteristics, shape,
structure and properties of individual
nanomaterials decide the properties.
Find use in high performance,
lightweight, energy savings and
environmental protection applications
-buildings and structures, automobiles
and aircrafts.
Nanocomposites

30. 30
Examples of nanocomposites include nanowires
and metal matrix composites.
Classified into multilayered structures and inorganic or
organic composites.
Multilayered structures are formed from self-assembly of
monolayers.
Nanocomposites may provide heterostructures formed from
various inorganic or organic layers, leading to multifunctional
materials.
Nanowires are made up of various materials and find its
application in microelectronics for semiconductor devices.

31. 31
All the properties of nanostructured
are controlled by changes in atomic
structure, in length scales, in sizes
and in alloying components.
Nanostructured materials are
formed by controlling grain sizes and
creating increased surface area per
unit volume.
Decrease in grain size causes
increase in volumetric fraction of
grain boundaries, which leads to
changes in fundamental properties of
materials.
Nanostructured Materials
Different behavior of atoms
at surface has been observed
than atom at interior.
Structural and
compositional differences
between bulk material and
nanomaterial cause change
in properties.

32. 32
The size affected properties are color, thermal conductivity,
mechanical, electrical, magnetic etc.
Nanophase metals show increase in hardness and modulus
of elasticity than bulk metals.
Nanostructured materials are produced in the form of
powders, thin films and in coatings.
Synthesis of nanostructured materials take place by Top –
Down or Bottom-Up method.
-In Top-Down method the bulk solid is decomposed into
nanostructure.
-In Bottom-Up method atoms or molecules are
assembled into bulk solid.
The future of nanostructured materials deal with controlling
characteristics, processing into and from bulk material and
in new manufacturing technologies.

33. 33
Nanofluids
Nanofluidsare engineered colloid formed with stable
suspemsions of solid nano-particles in traditional base
liquids.
Base fluids:Water, organic fluids, Glycol, oil, lubricants
and other fluids
Nanoparticle materials:
-Metal Oxides:
-Stable metals: Au, cu
-Carbon: carbon nanotubes (SWNTs, MWNTs),
diamond, graphite, fullerene, Amorphous Carbon
-Polymers : Teflon
Nanoparticle size:1-100 nm3
O2Al 2
ZrO 2
SiO 4
O
3
Fe

34. 34
Nanofluid Heat Transfer
Enhancement
Thermal conductivity enhancement
-Reported breakthrough in substantially increase
( 20-30%) in thermal conductivity of fluid by
adding very small amounts (3-4%) of suspended
metallic or metallic oxides or nanotubes.
Increased convective heat transfer
characteristic for heat transfer fluids as
coolant or heating fluid.
-

35. 35
Nanofluids and Nanofludics
Nanofluids have been investigated
-to identify the specific transport mechanism
-to identify critical parameters
-to characterize flow characteristics in macro,
micro and nano-channels
-to quantify heat exchange performance,
-to develop specific production, management
and safety issues, and measurement and
simulation techniques

36. 36
Nano-fluid Applications
Energy conversion and energy storage system
Electronics cooling techniques
Thermal management of fuel cell energy systems
Nuclear reactor coolants
Combustion engine coolants
Super conducting magnets
Biological systems and biomedicine

37. 37
Nano-Biotechnology
When the tools and processes of nanotechnology are
applied towards biosystems, it is called nanobiotechnology.
Due to characteristic length scale and unique properties,
nanomaterials can find its application in biosystems.
Nanocomposite materials can play great role in
development of materials for biocompatible implant.
Nano sensors and nanofluidcs have started playing an
important role in diagnostic tests and drug delivering system
for decease control.
The long term aim of nano-biotechnology is to build tiny
devices with biological tools incorporated into it diagonistic
and treatment..

38. 38
National Nanotechnology Initiative
in Medicine
Improved imaging (See: www.3DImaging.com)
Treatment of Disease
Superior Implant
Drug delivery system and treatment using
Denrimers, Nanoshells, Micro-and Nanofluidics
and Plasmonics

39. 39
-Nano-particles delivers
treatment to targeted area or
targeted tumors
-Release drugs or release
radiation to heat up and destroy
tumors or cancer cells
-In order to improve the
durability and bio-compatibility,
the implant surfaces are modified
with nano-thin film coating
(Carbon nano-particles).
-An artificial knee joint or hip
coated with nanoparticles bonds to
the adjacent bones more tightly.

40. 40
Self Powered Nanodevices and
Nanogenerators
Nanosize devices or machined need nano-size power
generator call nanogeneratorswithout the need of a
battery.
Power requirements of nanodevices or nanosystems are
generally very small
–in the range of nanowatts to microwatts.
Example:Power source for a biosensor
-Such devices may allow us to develop implantable
biosensors that can continuously monitor human’s
blood sugar level

41. 41
Waste energy in the form of vibrations or even the human pulse
could power tiny devices.
Arrays of piezoelectric could capture and transmit that waste energy
to nanodevices
There are many power sources in a human body:
-Mechanical energy, Heat energy, Vibration energy,
Chemical energy
A small fraction of this energy can be converted into electricity to
power nano-bio devices.
Nanogenerators can also be used for other applications
-Autonomous strain sensorsfor structures such as bridges
-Environmental sensors for detecting toxins
-Energy sensorsfor nano-robotics
-Microelectromecanical systems (MEMS) or
nanoelectromechanical system (NEMS)
-A pacemaker’s battery could be charged without
requiring any replacement

42. 42
Nano-sensor and Nano-generator
Nano-
sensor
Capacitor
Nano-
generator

43. 43
Example: Piezoelectric
Nanogenerator
Piezoelectric Effect
Some crystalline materials generates electrical voltage
when mechanically stressed
A Typical Vibration-based Piezoelectric Transducer
-Uses a two-layered beam with one end fixed
and other end mounted with a mass
-Under the action of the gravity the beam is bent with
upper-layer subjected to tension and lower-layer
subjected to tension.

44. 44
Conversion of Mechanical Energy to Electricity
in a Nanosystem
Tension Compression
Nanowire
Tension Compression
Nanowire
Rectangular electrode
with ridged underside.
Moves side to side in
response to external
motion of the
structure
Array of
nanowires (Zinc
Oxide) with
piezoelectric and
semiconductor
properties
Gravity do not play
any role for motion
in nanoscale.
Nanowire is flexed
by moving a ridged
from side to side.

45. 45
Example: Thermo Electric Nano-generator
Thermoelectric generator relies on the Seebeck Effect
where an electric potentialexists at the junction of
two dissimilar metals that are at different temperatures.
The potential difference or the voltage producedis
proportional to the temperature difference.
-Already used in Seiko Thermic Wrist Watch

46. 46
Bio-Nano Generators
Questions:
1. How much and what different kind of energy
does body produce?
2. How this energy source can be utilized to
produce power.
3. What are the technological challenges?