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Nanotechnology Nanotechnology in in

Mechanical EngineeringMechanical EngineeringPresented ByPresented By

Pradip MajumdarPradip MajumdarProfessorProfessor

Department of Mechanical EngineeringDepartment of Mechanical EngineeringNorthern Illinois UniversityNorthern Illinois University

DeKalb, IL 60115DeKalb, IL 60115

UEET 101 Introduction to Engineering

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Outline of the Presentation

Lecture In-class group

activities Video Clips Homework

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Course OutlineCourse Outline Lecture - ILecture - IIntroduction to Nano-Introduction to Nano-Technology in Technology in

EngineeringEngineering

Basic conceptsBasic concepts Length and time scales Length and time scales Nano-structured materials Nano-structured materials

- Nanocomposites- Nanocomposites

- Nanotubes and - Nanotubes and nanowirenanowire

Applications and Applications and ExamplesExamples

Lecture – Lecture – IIII

Nano-Nano-MechanicsMechanics Nanoscale Nanoscale Thermal Thermal and and FlowPhenomenaFlowPhenomena Experimental Techniques

Modeling andModeling and SimulationSimulation

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Lecture TopicsLecture Topics

We will address some of the key We will address some of the key issues of nano-technology in issues of nano-technology in Mechanical EngineeringMechanical Engineering. .

Some of the topics that will be Some of the topics that will be addressed are addressed are nano-structured nano-structured materialsmaterials; ; nanoparticles and nanoparticles and nanofluidsnanofluids, , nanodevices and nanodevices and sensorssensors, and , and applicationsapplications..

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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 RoboticsComputer-Aided Design (CAD/CAM)Computational Fluid Dynamics (CFD) and Finite Element Method Fabrication and Manufacturing processes

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x = 10 m x = 250 m x = 500 m x = 750 m x = 1000 m

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

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Length Scales in Sciences Length Scales in Sciences and Mechanicsand Mechanics

1010 810 610

Quantum Mechanicss

Molecular Mechanics

Nano-mechanics

310

Micro- mechanics

010

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

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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 gas with 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: Microscopic or Macroscopic model

20106

2010

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Microscopic Vs MacroscopicApproach -1: Microscopic viewpoint based 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.

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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

mlim

/VV

/V

V

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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

FP n

/AAlim

/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

2mN

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Introduction- Introduction- NanotechnologyNanotechnology

Nanoscale uses “nanometer” as the basic unit Nanoscale uses “nanometer” as the basic unit of measurement and it represents a of measurement and it represents a billionth billionth of a meterof a meter or one billionth of a part. or one billionth of a part.

Nanotechnology deals with Nanotechnology deals with nanosized nanosized particlesparticles and and devicesdevices

One- One- nmnm is about 3 to 5 atoms wide. This is is about 3 to 5 atoms wide. This is very tiny when compared normal sizes very tiny when compared normal sizes encounter day-to-day. encounter day-to-day.

- For example this is 1/1000- For example this is 1/1000thth the width of the width of human human

hair.hair.

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Any physical substance or device Any physical substance or device with structural dimensions below with structural dimensions below 100 nm is called nanomaterial or 100 nm is called nanomaterial or nano-device. nano-device.

Nanotechnology rests on the Nanotechnology rests on the technology that involves fabrication technology that involves fabrication of material, devices and systems of material, devices and systems through direct control of matterthrough direct control of matter at at nanometer length scalenanometer length scale or less or less than 100 nm. than 100 nm.

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Nanoparticles can be defined as building blocks of Nanoparticles can be defined as building blocks of nanomaterials and nanotechnology. nanomaterials and nanotechnology.

Nanoparticles include Nanoparticles include nanotubesnanotubes, , nanofibersnanofibers, , fullerenesfullerenes, , dendrimersdendrimers, , nanowiresnanowires and may be and may be made of ceramics, metal, nonmetal, metal oxide, made of ceramics, metal, nonmetal, metal oxide, organic or inorganic. organic or inorganic.

At this At this small scalesmall scale level, the physical, chemical and level, the physical, chemical and biological properties of materials biological properties of materials differdiffer significantly significantly from the fundamental properties at from the fundamental properties at bulk levelbulk level. .

Many Many forces or effectsforces or effects such inter-molecular forces, such inter-molecular forces, surface tension, electromagnetic, electrostatic, surface tension, electromagnetic, electrostatic, capillary becomes significantly more dominant than capillary becomes significantly more dominant than gravity.gravity.

Nanomaterial can be Nanomaterial can be physically and chemically physically and chemically manipulatedmanipulated to alter the properties, and these to alter the properties, and these properties can be measured using nanoscale sensors properties can be measured using nanoscale sensors and gages.and gages.

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A structure of the size of an atom A structure of the size of an atom represents one of the fundamental limit.represents one of the fundamental limit.

Fabricating or making anything smaller Fabricating or making anything smaller require manipulation in atomic or require manipulation in atomic or molecular level and that is like changing molecular level and that is like changing one chemical form to other.one chemical form to other.

Scientist and engineers have just started Scientist and engineers have just started developing new techniques for making developing new techniques for making nanostructures.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.

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Nanotechnology in Nanotechnology in Mechanical Mechanical EngineeringEngineering

New Basic Concepts

Nano-Mechanics Nano-Scale

Heat Transfer Nano-fluidics

Applications

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ApplicationsApplications

Structural materialsStructural materials Nano devices and sensorsNano devices and sensors Coolants and heat spreadersCoolants and heat spreaders LubricationLubrication Engine emission reduction Engine emission reduction Fuel cell – nanoporous Fuel cell – nanoporous

electrode/membranes/nanocatalyst electrode/membranes/nanocatalyst Hydrogen storage mediumHydrogen storage medium Sustainable energy generation - Photovoltaic Sustainable energy generation - Photovoltaic

cells for power conversioncells for power conversion Biological systems and biomedicineBiological systems and biomedicine

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Basic ConceptsBasic Concepts

Energy CarriersEnergy Carriers

Phonon:Phonon: Quantized lattice vibration Quantized lattice vibration energy with wave nature of propagationenergy with wave nature of propagation

- dominant in crystalline material- dominant in crystalline material

Free Electrons:Free Electrons:

- dominant in metals- dominant in metals

Photon:Photon: Quantized electromagnetic Quantized electromagnetic energy with wave nature of propagationenergy with wave nature of propagation

- energy carrier of radiative energy- energy carrier of radiative energy

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Length ScalesLength ScalesTwo regimes:Two regimes:I. Classical microscale size-effect domain I. Classical microscale size-effect domain – –

Useful for microscale heat transfer in micron-size Useful for microscale heat transfer in micron-size environment.environment.

cL

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(OccL

c

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This length scale will provide the This length scale will provide the guidelines for analysis method- both guidelines for analysis method- both theoretical and experimental theoretical and experimental methods:methods:

classical microscale domain classical microscale domain or or nanoscale size-effect domain.nanoscale size-effect domain.

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Flow in Nano-channelsFlow in Nano-channels The Navier –Stokes (N-S) equation of continuum model fails when the 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 gradients of macroscopic variables become so steep that the length scale is of the order of average distance traveled by the molecules between collision.the order of average distance traveled by the molecules between collision.

Knudsen numberKnudsen number ( ( ) is typical parameter used to classify the ) is typical parameter used to classify the length length

scale and flow regimes: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.

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Time ScalesTime Scales

Relaxation timeRelaxation time for different collision for different collision process:process:

Relaxation time for Relaxation time for phonon-electron phonon-electron interaction: interaction:

Relaxation time for Relaxation time for electron-electron electron-electron interaction: interaction:

Relaxation time for Relaxation time for phonon-phonon phonon-phonon interaction: interaction:

)s 1110( O

)s 1310( O

)s 1310( O

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Nanotechnology: Modeling Nanotechnology: Modeling MethodsMethods

Quantum MechanicsQuantum Mechanics Atomistic simulationAtomistic simulation Molecular Mechanics/DynamicsMolecular Mechanics/Dynamics

NanomechanicsNanomechanics

Nanoheat transfer and Nanoheat transfer and NanofluidicsNanofluidics

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Models for Inter-molecules ForceModels for Inter-molecules Force

- Inter-molecular Potential - Inter-molecular Potential

Model Model

- Inverse Power Law Model or - Inverse Power Law Model or

Point Centre of Repulsion Point Centre of Repulsion

ModelModel

- Hard Sphere Model- Hard Sphere Model

- Maxwell Model - Maxwell Model

- Lennard-Jones Potential - Lennard-Jones Potential

ModelModel

Inter-Molecular Distance

Force

Inter-Inter-molecular molecular Potential Potential ModelModel

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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 devices and 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.

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Nanoparticles and Nanoparticles and NanomaterialsNanomaterials

Nanoparticles:Nanoparticles:

Nanoparticles are significantly larger than individual Nanoparticles are significantly larger than individual atoms and molecules. atoms and molecules.

Nanoparticles are not completely governed by either Nanoparticles are not completely governed by either quantum chemistry or by laws of classical physics. quantum chemistry or by laws of classical physics.

Nanoparticles have high surface area per unit Nanoparticles have high surface area per unit volume.volume.

When material size is reduced the number of atoms When material size is reduced the number of atoms on the surface increases than number of atoms in on the surface increases than number of atoms in the material itself. This surface structure dominates the material itself. This surface structure dominates the properties related to it. the properties related to it.

Nanoparticles are made from chemically stable Nanoparticles are made from chemically stable metals, metal oxides and carbon in different forms.metals, metal oxides and carbon in different forms.

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Carbon -Nanotubes Carbon nanotubes are hollow

cylinders made up of carbon atoms.

The diameter of carbon nanotube is few nanometers and 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.

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There are four types of carbonnanotube: Single Walled CarbonNanotube (SWNT), Multi WalledXarbon nanotube (MWNT),

Fullereneand Torus. SWNTs are made up of singlecylindrical grapheme layer

MWNTs is made up of multipleGrapheme layers. SWNT possess important electricproperties which MWNT does not.

SWNT are excellent conductors, so finds its application in miniaturizing electronics components.

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Formed by combining two or more Formed by combining two or more nanomaterials to achieve better nanomaterials to achieve better properties. properties.

Gives the best properties of each Gives the best properties of each

individual nanomaterial. individual nanomaterial.

Show increase in strength, modulus Show increase in strength, modulus of elasticity and strain in failure. of elasticity and strain in failure.

Interfacial characteristics, shape, Interfacial characteristics, shape, structure and properties of structure and properties of individual nanomaterials decide the individual nanomaterials decide the properties. properties.

Find use in high performance, lightweight, energy savings and environmental protection applications

- buildings and structures, automobiles

and aircrafts.

NanocompositesNanocomposites

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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.

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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.

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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.

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NanofluidsNanofluidsNanofluidsNanofluids are engineered colloid formed with stable are engineered colloid formed with stable

suspemsions of solid nano-particles in traditional base suspemsions of solid nano-particles in traditional base liquids.liquids.

Base fluids:Base fluids: Water, organic fluids, Glycol, oil, Water, organic fluids, Glycol, oil, lubricants and other fluidslubricants and other fluids

Nanoparticle materials:Nanoparticle materials: - Metal Oxides: - Metal Oxides: - Stable metals: Au, cu- Stable metals: Au, cu - Carbon: carbon nanotubes (SWNTs, MWNTs), - Carbon: carbon nanotubes (SWNTs, MWNTs), diamond, graphite, fullerene, Amorphous Carbondiamond, graphite, fullerene, Amorphous Carbon - Polymers : Teflon- Polymers : TeflonNanoparticle size:Nanoparticle size: 1-100 nm 1-100 nm

3O2Al 2ZrO 2SiO 4O3Fe

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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.

-

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Nanofluids and Nanofluids and NanofludicsNanofludics

Nanofluids have been investigated Nanofluids have been investigated - to identify the specific transport mechanism - to identify the specific transport mechanism

- to identify critical parameters - to identify critical parameters - to characterize flow characteristics in macro, - to characterize flow characteristics in macro, micro and nano-channelsmicro and nano-channels - to quantify heat exchange performance, - to quantify heat exchange performance, - to develop specific production, management - to develop specific production, management and safety issues, and measurement and and safety issues, and measurement and simulation techniquessimulation techniques

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Nano-fluid ApplicationsNano-fluid Applications

Energy conversion and energy storage Energy conversion and energy storage systemsystem

Electronics cooling techniquesElectronics cooling techniques Thermal management of fuel cell energy Thermal management of fuel cell energy

systemssystems Nuclear reactor coolantsNuclear reactor coolants Combustion engine coolantsCombustion engine coolants Super conducting magnetsSuper conducting magnets Biological systems and biomedicineBiological systems and biomedicine

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Nano-BiotechnologyNano-Biotechnology When the tools and processes of When the tools and processes of nanotechnology are applied towards nanotechnology are applied towards biosystems, it is called nanobiotechnology. biosystems, it is called nanobiotechnology.

Due to characteristic length scale and Due to characteristic length scale and unique properties, unique properties, nanomaterials can find its application in nanomaterials can find its application in biosystems. biosystems.

Nanocomposite materials can play great role Nanocomposite materials can play great role in development of materials for biocompatible in development of materials for biocompatible implant. implant.

Nano sensors and nanofluidcs have started Nano sensors and nanofluidcs have started playing an important role in diagnostic tests playing an important role in diagnostic tests and drug delivering system for decease and drug delivering system for decease control. control.

The long term aim of nano-biotechnology is The long term aim of nano-biotechnology is to build tiny devices with biological tools to build tiny devices with biological tools incorporated into it diagonistic and treatment.. incorporated into it diagonistic and treatment..

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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

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-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.

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Self Powered Nanodevices and Nanogenerators

Nanosize devices or machined need nano-size power generator call nanogenerators without 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

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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 sensors for structures such as

bridges - Environmental sensors for detecting toxins - Energy sensors for nano-robotics - Microelectromecanical systems (MEMS) or nanoelectromechanical system (NEMS) - A pacemaker’s battery could be charged without requiring any replacement

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Nano-sensor and Nano-generator

Nano-sensor Capacitor

Nano-generator

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Example: Piezoelectric Nanogenerator

Piezoelectric Effect Some crystalline materials generates electrical

voltage when mechanically stressedA 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.

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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.

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Example: Thermo Electric Nano-generator

Thermoelectric generator relies on the Seebeck Effect where an electric potential exists at the junction 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

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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?