UEET 101 Introduction to Engineering
Pradip Majumdar, Ph.D
Department of Mechanical Engineering
Northern Illinois University
DeKalb, IL 60115
Outline of the Presentation
In-class group activities and
Lecture - I Lecture – II
Basic concepts Nano-Mechanics
Length and time scales Nanoscale Thermal
Nano-structured materials and Flow
- Nanocomposites Phenomena
- Nanotubes and
Examples Modeling and
Key issues of nano-technology in Mechanical
Topics to be addressed are basic concepts,
length and time scales, nano-structured
materials; nanoparticles and nanofluids,
nanodevices and sensors, and applications.
Major Topics in Mechanical Engineering
Statics : Deals with forces, Moments, Design of machines and
equilibrium of a stationary body structures
Dynamics: Deals with body in Dynamics system, sensors
motion - velocity, acceleration, and controls
torque, momentum, angular - Robotics
momentum. Computer-Aided Design
Structure and properties of (CAD/CAM)
material (Including strengths) - Solid model and Analysis
Thermodynamics, power Computational Fluid
generation, alternate and Dynamics (CFD) and
regenerative energy (power plants, Finite Element Method
solar, wind, geothermal, engines, Fabrication and
nuclear, fuel cells and battery Manufacturing processes
Length Scales in Sciences and
Regimes of Mechanics Deals with atoms -
Molecular Networks -
Quantum Molecular Nano- Micro- Macro-
Mechanics Mechanics mechanics mechanics Mechanics
-deals with Nano-
10 10 10 9 106 10 3 100 Micromechanics:
Length Scales (m)
Altosecond (ps) Second
10 18 10 15 10 12 10 9 10 6 10 3 10 0
Electron – Photon relaxation time: 0.5 – 50 ps
Material heating and melt with high energy laser : 1-10
Ultrafast Lasers: (macro-micro second lasers:
CW laser, ND-YAG, Diode
- Laser ablation of material removal process
- Correction of eye surface
- Excimer Laser Ablation
Only a thin skin (100-200nm) absorbs
the laser energy and vaporizes 8
Quantum and Molecular Mechanics
All substances are composed molecules or
atoms in random motion.
A gas system consisting of a cube of 25-mm on
each side contains 1020 atoms.
To describe the behavior of this system, we need
to deal with at least 6 1020 equations.
A computational challenge - even with the most
powerful computer available today.
There are two approaches to handle this
situations: Microscopic or Macroscopic
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
Changes one chemical form to other.
Microscopic Vs Macroscopic
Microscopic viewpoint -kinetic theory and statistical mechanics
On the basis of statistical considerations and probability theory,
it deals with average values of all atoms or molecules in
connection with a atomic model.
Macroscopic view point - continuum assumption.
Consider gross or average behavior of a number of molecules
Deals 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 known as continuum.
Breakdown of Continuum Model
Limit of continuum or macroscopic model
Density is defined as the mass
per unit volume and expressed as
lim / V
V V V / V
Where V / is the smallest volume for which substance
can be assumed as continuum.
Volume smaller than this will leads to the fact that mass
is not uniformly distributed, but rather concentrated in
particles as molecules, atoms, electrons etc.
Density varies as volume decreases below the continuum
Macroscopic Properties and
Pressure is defined as the Measurement
of force per unit area and
P lim Fn
A A / A
For a pressure gauge, it is the
Where A / is the smallest average force (rate of change of
volume for which substance can momentum) exerted by the
be assumed as continuum. randomly moving atoms or
Unit: Pascal (Pa) or N molecules over the sensor’s area.
Nanoscale uses “nanometer” as the basic unit of
measurement and it represents a billionth of a
meter or one billionth of a part.
Nanotechnology deals with nanosized particles
One- nm is about 3 to 10 atoms wide. This is very
tiny when compared with normal sizes encountered
- For example, this is 1/1000th the width of human
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 matter at
nanometer length scale.
Departure from continuum assumption.
Exhibit unusual mechanical, optical, chemical
and physical properties. 15
Nanoparticles are the building blocks of
nanomaterials and nanotechnology.
Nanoparticles include graphene, nanotubes,
nanofibers, fullerenes, dendrimers,
Nanoparticles are made of ceramics, metals,
nonmetals, metal oxide, organic or
Behavior Different from Bulk or
At this small scale level, the physical, chemical and
biological properties of materials differ significantly
from the fundamental properties at bulk level.
Many forces or effects such as inter-molecular forces,
surface tension, electromagnetic, electrostatic, capillary
becomes significantly more dominant than gravity.
Nanomaterial can be physically and chemically
manipulated to alter the properties that are measured
using nanosensors and nanogages.
Scientist and engineers have just started developing
new techniques for making nanostructures.
-The nanoscience has
- The age of nanofabrication
Nanofabrication Nanotechnology is here.
-The age of nanotechnology –
that is the practical use of
nanostructure has just started.
Nanotechnology in Mechanical
Nano devices and sensors
Coolants, heat spreaders and lubrication
Engine emission reduction
Fuel cell and Battery storage – nanoporous
Hydrogen storage medium
Sustainable energy generation - Photovoltaic cells
for power conversion
Biological systems and biomedicine
Phonon: Quantized lattice vibration energy with wave
nature of propagation
- dominant energy carrier in crystalline material
- dominant energy career in metals
Photon: Quantized electromagnetic energy with wave
nature of propagation
- energy carrier of radiation energy of
I. Classical microscale size-effect domain – Useful for
microscale phenomena in micron-size environment.
m m mean free path length of the substance
Lc characteristic device dimension
II. Quantum nanoscale size-effect domain –
More relevant to nanoscale phenomena
c characteristic wave length of the electrons
Relaxation time for different collision process:
Relaxation time for phonon-electron
interaction: O (1011 s)
Relaxation time for electron-electron
interaction: O (1013 s)
Relaxation time for phonon-phonon
interaction: O (1013 s)
Nanoheat transfer and Nanofluidics
Models for Inter-molecules Force
- Inter-molecular Potential
- Inverse Power Law Model or Force
Point Centre of Repulsion Inter-Molecular Distance
- Hard Sphere Model
- Maxwell Model
- Lennard-Jones Potential
Nanotools are required for manipulation of matter at
nanoscale or atomic level.
Devices which manipulate matter at atomic or
molecular level are Transmission electron microsope
(TEM), Scanning-probe microscopes, atomic force
microscopes, atomic layer deposition devices and
Nanolithography creates nanoscale structure by etching
Nanotools comprises of fabrication techniques, analysis
and instruments and software.
Softwares are utilized in nanolithography, 3-D printing,
nanofluidics and chemical vapor deposition.
Nanoparticles and Nanomaterials
Nanoparticles are significantly larger than
individual atoms and molecules.
Nanoparticles are not completely governed by
either quantum chemistry or by laws of
Nanoparticles have high surface area per unit
With reduced size, the number of atoms on
the surface increases than that in the interior.
The surface structure dominates the
Carbon nanotubes are hollow
cylinders made up of carbon
The diameter of carbon nanotube is
few nanometers and they can be
several millimeters in length.
Carbon nanotubes looks like rolled
tubes of graphene and their walls are
like hexagonal carbon rings and are
formed in large bundles.
Have high surface area per unit
Carbon nanotubes are 100 times
stronger than steel at one-sixth of
Carbon nanotubes have the ability to
sustain high temperature ~ 2000
There are four types of carbon
nanotube: Single Walled Carbon
Nanotube (SWNT), Multi Walled
carbon nanotube (MWMNT),
Fullerene and Torus.
SWNTs are made up of single
cylindrical graphene layer
MWNTs is made up of multiple
SWNT possess important electric
properties which MWNT does not.
SWNT are excellent conductors, so
finds its application in miniaturizing
Formed by combining two or more
nanomaterials to achieve better
Gives the best properties of each
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 30
Examples of nanocomposites include nanowires
and metal matrix composites.
Classified into multilayered structures of inorganic or
Multilayered structures are formed from self-assembly of
Nanocomposites may provide heterostructures formed from
various inorganic or organic layers, leading to
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 Different behavior of atoms
and creating increased surface at surface has been observed
area per unit volume. than atom at interior.
Decrease in grain size causes Structural and
increase in volumetric fraction of compositional differences
grain boundaries, which leads to between bulk material and
changes in fundamental properties of nanomaterial cause change
materials. in properties. 32
The size affected properties are color, thermal conductivity,
mechanical, electrical, magnetic etc.
Nanostructure material 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
- 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 and33
Nanofluids are engineered colloid formed with stable
suspemsions of solid nano-particles in traditional
Base fluids: Water, organic fluids, Glycol, oil, lubricants
and other fluids
- Metal Oxides: Al 2O3 ZrO2 SiO2 Fe 3O 4
- Stable metals: Au, cu
- Carbon: carbon nanotubes (SWNTs, MWNTs),
diamond, graphite, fullerene, Amorphous Carbon
- Polymers : Teflon
Nanoparticle size: 1-100 nm
Nanofluid Heat Transfer
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 cooling characteristic
of coolant or heating fluid.
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
When the tools and processes of nanotechnology are
applied towards biosystems, it is called nanobiotechnology.
Due to smaller length scale and unique properties,
nanomaterials can find its application in biosystems.
Nanocomposite materials play a 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 for
diagonistic and treatment.
National Nanotechnology Initiative
Improved imaging (www.3DImaging.com) for
Treatment of Disease
Drug delivery system and treatment using
Denrimers, Nanoshells and Nanofluidics.
- In order to improve the
durability and bio- Nano-particles delivers
compatibility, the implant treatment to targeted area
surfaces are modified with or targeted tumors
nano-thin film coating - Release drugs or release
(Carbon nano-particles). radiation to heat up and
- An artificial knee joint or hip destroy tumors or cancer
coated with nanoparticles bonds to cells
the adjacent bones more tightly. 39
Self Powered Nanodevices and
Nanosize devices or machined need nano-size power
generator called nanogenerators without the need of
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
Waste energy in the form of vibrations or even the
human pulse could power tiny devices.
Arrayof piezoelectrics could capture and transmit that waste
energy to nanodevices
Power sources in a human body:
- mechanical energy, heat energy, vibration 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 sensors for structures such as bridges
- Environmental sensors for detecting toxins
- Energy sensors for nano-robotics
- A pacemaker’s battery could be charged without
requiring any replacement
Nano-sensor and Nano-generator
sensor Capacitor generator
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 compression. 43
Conversion of Mechanical Energy to Electricity
in a Nanosystem
Gravity do not play
any role for motion
Tension Compression Tension Compression in nanoscale.
Nanowire is flexed
by moving a ridged
from side to side.
nanowires (Zinc Rectangular electrode
Oxide) with with ridged underside.
piezoelectric and Moves side to side in
semiconductor response to external
properties motion of the
Example: Thermo Electric Nano-generator
Thermoelectric generator relies on the Seebeck Effect
where an electric potential exists at the junctions of
two dissimilar metals that are at different temperatures.
The potential difference or the voltage produced is
proportional to the temperature difference.
- Already used in Seiko Thermic Wrist Watch
In-class group activities
and Home Work
Work in a group to discuss following Questions on Bio-Nano
1. How much and what different kind of energy
does body produce?
2. How this energy source can be utilized to
3. What are the technological challenges?
Expand your answers and submit as a homework
The link to the video.