Transcript رابطة المبعوثين العائدين من الخارج برعا

‫رابطة المبعوثين العائدين من الخارج‬
‫برعاية ا‪.‬د‪ /.‬فرحة الشناوي‬
‫الندوة المجمعة األولى‬
‫تكنولوجيا النانو‬
‫‪1‬‬
‫د‪/‬عبد الكريم أبو الوفا‬
‫كلية العلوم‬
‫‪Nano wires‬‬
‫‪2‬‬
‫ا‪.‬د‪/.‬محمد نبيل صبري‬
‫كلية الهندسة‬
‫‪Nano devices‬‬
What is nanotechnology?
0.1n 1n 10n 100n 1m 10m 100m
H2O
DNA
Virus
1cm
1m
White
blood
cell
Human
hair
NEMS/MEMS
Nano devices
 Nano tubes
 Nano transistors 100m
 Quantum dots
 ...
No sharp
Frontiers!
Why is it special?
Ability to act on phenomena
previously uncontrolled:
 Physical properties
 Chemical reactions
 Biological transformations
This lecture is mainly about:
Potentials AND Risks
How is it fabricated?
Two approaches
Top – down
Bottom – up
Cutting a nano piece out of a bulk
(used in microelectronics)
(self ) Assembling tiny objects
into Nano devices
H-bond
DNA-like
molecules
Assembles to:
Top – Down main processes
 Lithography
 Photolithography
 Electron beam lith.
 Ion implantation
 Thermal treatment
 Etching
 Wet etching
 Dry etching
 Deposition
 Chemical Vapor Dep. CVD
 Physical Vapor Dep. PVD
…
Top – Down example: a nano-switch 1
1-LPCVD
Si3N4-125n
Patterning
2-Photolithography
Photo-resist
Si-125m
Exposing
3-Reactive Ion Etching
RIE (He + SF6)
4- Wet Etching (KOH)
Top – Down example: a nano-switch 2
5-Patterning
6-Resist + Deposition of Cr (60n) +
Electron beam lithography
1m
7- Deposition of Cr (5n) + Au (70n)
8-RIE
Carbon Nano Tubes (CNT)
Take a sheet of carbon atoms …
Roll it!
Carbon Nano Tube: Strength = 100 x Steel; Weight = 1/6 x Steel
You still need to assemble many of them to be useful!
Prof. Richard Smalley (Rice U.): “it would take a single nanoscopic machine millions of years to
assemble a meaningful amount of material.!”
Eric Drexler believes assemblers could replicate themselves, resulting in exponential growth.
http://science.howstuffworks.com/nanotechnology4.htm
Bottom – Up example: a cantilever
Cantilever beam material
Fe2O3 nano
Polyelectrolyte
particles
CNT
Creating cantilever structure
Biomedical Applications
Lab on a chip
Manipulating drops
(micro-fluidic) (video)
Detecting Molecules
“Artificial nose”!
Drug delivery systems
Nano devices are smaller than cells
Nano devices
can easily enter
in cells for early
detection of cancer
In vivo
Cell size: 1 – 2 m
National
Cancer
Institute
More efficient cancer test
National
Each cantilever can capture one specific type of molecules Cancer
Institute
Cantilever bending: electronically detected
Nano-pores help reading DNA code
Nano-pores: DNA passes through one strand at a time,
DNA sequencing more efficient.
Monitor shape & electrical properties of each
base, or letter,
Hence, decipher the encoded information,
including errors associated with cancer.
National
Cancer
Institute
Nano-pores in Aluminum
100 n
Using CNT to detect DNA defects
National
Cancer
Institute
A Nano-tube
(sharp edged pin)
Traces the shape of
DNA, making a map
Using quantum dots to detect cancer
Quantum dots:
Crystals (few nm) with size dependent optical properties
UV stimulus: They glow (size dependent color)
National
Can be designed to bind to specific DNA sequences.
Cancer
(to detect and treat cancer cells)
Institute
Dendrimers: the complete solution!
Cancer
Cell
Drug
Cancer
detector
Dendrimers
Cancer
detector
Cell death
Monitor
Man-made molecules (~ a protein).
Shape gives vast amounts of surface area
Can attach therapeutic agents or other biologically active molecules.
Programmable nano – robots!
A near future dream!
Patients will drink fluids containing nano-robots programmed to
attack and reconstruct the molecular structure of cancer cells.
Nanorobots could also perform
delicate surgeries
more precise than the
sharpest scalpel
[source: International Journal
of Surgery]
Nano for Energy
4th Generation
Solar Cells
Fuel Cells
Energy Harvesting
Solar Energy
World electric power demand: ~
14 TW
Incident Solar power:
120, 000 TW!!
Consider 10% efficiency,
& exclude oceans and cities:
600 TW
Average extractable power
from Egyptian desert alone:
15 TW
Solar energy economics
Not only efficiency matters, but also cost!
$ 0.1/ W
$ 0.2/ W
$ 0.5/ W
100
Thermodynamic
Limit
Efficiency (%)
80
60
$ 1.0/ W
III
40
Theoretical
Limit
20
IV
0
II
100
$ 3.5/ W
I
200
300
Cost $ / m 2
400
500
Prof. Rastogi,
Binghamton U.
Expected grid parity: year 2012 – 2018 (depending on region)
[source iSupply Applied Market Intelligence]
Nano pillars for solar cells
Radiation losses
due to reflection
900n
Anti Reflection Coating
Using Nano Pillars
Thin film solar cells
Prof. Rastogi,
Binghamton U.
Thin film:  small amount of Si (+amorphous Si)  Low initial price
Flexible:  low installation cost
Quantum dots for solar cells – 1
Conduction band
Energy
Band gap
Donors level
Electrons
Valence band
Incident Photons
Losses for both too high
and too low energy photons
Need to have
“adjustable” band gaps ??
Quantum dots for solar cells – 2
Conduction band
Energy
Band gap
Valence band
For Quantum dots:
Band Gap is size dependent:
Make many sizes to capture
all incident photons
Small size:
Highly excited electron can
share energy with another one
Fuel cells
Fuel can be H2
or other
hydrocarbons
Membrane
(heart of the device)
passes H ions only
Platinum
catalysts
Heat (~85oC)
Can power
Handheld devices
Up to trucks
Environmental impact of burning fuel
U.S.
Nano improvements of fuel cells
Higher efficiency membrane
Higher surface area and lower quantity of
catalyst (Platinum)
New less expensive catalyst materials
Energy harvesting: Thermo-ionic effects
DV (open circuit) = S (Thot – Tcold) S: Seebeck Coefficient
Materials A & B can be:
- Two different metals
- Semiconductors with different doping
When connected to a load:
W = h Qhot
h < 1 – Tcold/Thot
h increases with: S, s (elec cond)
h decreases with k (thermal cond)
Figure of merit Z =
S2
s/k
Metal/Semiconductor
Nano composites: Very High Z
Thot
Heat Qhot (W)
Material B
Material B
DV
Power
W (W)
Material A
Tcold
Heat Qcold (W)
Nanopiezotronics
Energy harvesting: nano brush
Zinc oxide
nano wires
4-layer integrated nano generator:
Output power: 0.11 µW/cm2
at a voltage of 62 mV.
Nano Electronics is here since long!
A transistor
Gate
Source
Oxide
thickness
~ 10n
Drain
Channel length
< 45 nano
Major problem: heat!
The growing power density (measured in W/cm2) of Intel's
microchip processor families. (Source: Intel)
R&D issues in thermal effects
 Modeling & Simulation
 Multiple Physics (Mainly Electro-thermal)
 Multiple Scales (transistor  data center )
 Compact Thermal Models:
New technology for multiple source problems: 3D – ICs, SoC …
 High performance simulation/optimization tools
Micro-fluidics & micro heat transfer
 Micro-channels
 Micro effects in 2 phase: Electro wetting/micro-boiling
 Integrated micro/nano coolers
 TACS Temperature Aware Computer Systems
 Thermal aware layout
 Thermal aware operating systems (ex: scheduling …)
Other R&D trends
Flexible flat display panels using nanowires
 NEMS for high density memory (terabyte/ in2)
 Molecular sized transistors
 Self aligned nanostructures to build integrated circuits
Nanotechnology impact on environment
Pros:
 A high potential for new and renewable energies
 Less CO2 emission
 A high potential for pollution detection
 A high potential for water treatment:
 Composition detection
 Desalination
 Waste water treatment
 Solution of many health problems
BUT …!
Nanoparticles may
accumulate in vital organs,
creating a toxicity problem.
 Use of toxic, basic or acidic
chemicals organic solvents
 99% of materials used are not in
final product
 Actual manufacturing of
nanodevices is highly energy intensive
 Unknown impact of nanoparticles on
natural cells
Conclusion
 Nanotechnology is not the future, it is
the present and the near future
 Nanotechnology has highly promising
applications in almost all engineering,
medical, environmental … issues.
It is inherently multi-disciplinary
 Side effects, potentially harmful, are not yet
quite well assessed.
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