Nanotechnology - ltu

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Transcript Nanotechnology - ltu

Nanotechnology
Bob Aikenhead
Faculty of Education (Bundoora)
Origins of Nanoscience
Dawn of nanoscale science:
• Richard Feynman gave a lecture on
December 29th, 1959 at the annual
meeting of the American Physical Society
at the California Institute of Technology. He
suggested that it is possible to control the
manipulation of matter at the scale of
individual atoms and molecules
NanoTechnology
here’s what it means:
• Nano – one billionth.
Something divided into a million bits then each
bit divided into a thousand smaller bits.
• Technology – building things.
• Nanotechnology – building things from
very tiny parts.
Nanotechnology is a ‘buzz’ word.
There is lots of hype about it.
But ….There is nothing fundamentally new
about making things from tiny parts.
It has been happening in nature ever since
the universe began:
living things are made from cells.
and all substances are made from atoms.
What’s new is the technology part.
Through science we understand much
about how tiny objects ‘work’:
about atoms & molecules and cells.
Now we can start to copy what
happens in nature and to make new
things using these methods.
In nature objects of tiny size are formed all
the time.
Tiny objects, atoms, molecules, cells, join
together to make larger and more complex
things.
The natural world around us is made of a
vast number of interacting parts, building
up in size from very tiny to very large.
Until recently our crafts and technologies
have been able to work only with objects
that have sizes on the human scale – from
hundreds of metres to a fraction of a
millimetre.
Though science & technology humans now
have the ability to manipulate tiny sized
objects – smaller than the parts in
a living cell.
Even as small as individual atoms.
Picture source:
cnx.org/content/m14353/latest/
Individual atoms placed with Scanning Tunnelling Microscope (STM)
Iron atoms on copper – formed with Scanning Tunnelling Microscope (STM)
Image source: http://www.cite-sciences.fr/english/ala_cite/exhibitions/nanotechnologies/images/diapo01/04-stm11.jpg
Nanotechnology is the ability to work with
objects on the nanoscale.
We can work with these tiny objects in many
different ways.
Before looking at these in more detail we will try
to get an idea of the size
of the objects which exist in
the nano-world.
A journey from the everyday world
to the nano-world.
100 m
10-4 m 1 metre
10-5 m
10-1 m
1 centimetre
10-6 m
10-7 m
1 micrometre
10-2 m
1 millimetre
10-8 m
10-3 m
10-9 m
10-10 m
1 nanometre
A photograph
about 1 metre across
100 metre
A photograph
about 10 cm across
10-1 metre
A photograph
about 1 cm across
10-2 metre
A photograph through light microscope
about 1 mm across
10-3 metre
A photograph through light microscope
about 0.1 mm across
10-4 metre
A photograph through light microscope
about 0.01 mm across
10-5 metre
Electron microscope image
about 0.001 mm across
10-6 metre
Electron microscope image
about 0.0001 mm across
10-7 metre
Computer generated image
about 0.00001 mm across
10-9 metre
Computer generated image
about 0.000001 mm across
10-9 metre
Computer generated diagram
about 0.0000001 mm across
10-10 metre
In our everyday technologies we have different
approaches to making things.
Here are two examples from the
(ancient) building industry.
We can start with large
objects and work down, by
removing material, until
we get the shape we want.
Ellora rock cut temple, India.
We can start with small
objects and work up, by
adding material, until we
get the shape we want.
Great pyramid, Egypt.
We sometimes reshape material – like a potter.
We sometimes work away a material – like a sculptor.
We sometimes combine materials – like house builder.
Temple hewn from solid rock.
Ellora caves, central India
Pyramid built from individual blocks of stone.
Egypt
Nanotechnology also means working in many
ways:
• reshaping materials
• carving smaller parts from larger ones
• combining different materials
• building large objects from smaller units
All at the nano scale – with things about a
thousand millionth of a metre in size.
Some simple existing applications of
nanotechnology:
Sunscreen
http://www.oxonica.com/optisol.htm
Self cleaning windows
http://www.chippingsodburyglass.co.uk/selfclean.htm
Catalyst for diesel engines
http://www.cerulean-international.com/products.htm
Nanodiamonds
http://www.plasmachem.com
All these are based just on the small size of the particles.
Nano crystals of titanium dioxide absorb
ultra violet radiation but don’t affect visible
light.
Larger particles in ordinary sunscreen
reflect visible light and so appear white.
As the nano crystals are much smaller than
the wavelength of visible light that light
passes through the nano layer – it is
transparent.
So we have sunscreen which is invisible but
it more effective at blocking uv than regular
sunscreen.
Self cleaning glass has a nanolayer
of titanium dioxide coating on the
surface. This acts in two ways:
First, it is photocatalytic: UV rays,
abundant on even the cloudiest of
days, cause the glass to react
chemically with dirt and organic
deposits, breaking them down and
loosening them from the surface of
the glass.
Secondly, it is hydrophilic: it attracts water, which slides
down and off the surface of the glass without forming
into separate droplets. This ensures that loose particles
of dust and dirt are easily washed off during normal rainy
weather.
Envirox™ fuel additive is a scientifically and commercially
proven diesel fuel combustion improver which reduces
fuel consumption and also reduces harmful exhaust
emissions.
It is based on the use of cerium oxide nanoparticles which
are a catalyst for the burning of carbon . Any carbon
particles left from the diesel fuel burn up at lower
temperature.
The exhaust is cleaner and more energy is obtained –
which lowers fuel consumption
Nano sized diamonds with an average diameter of
4 nano-metre, have many uses including polishing of:
• Lapping and polishing applications
• Nickel Plated Rigid Memory Disk
• Al-Rigid Memory Disk Substrate
• Polycarbonate and CR-39 Eyeglass Lenses
• Miniature and Precision Ball Bearings
• Optical and Laser Optical Components
• Orthopedic Prostheses
• Precious Stones
• Honing Microtome Knives
• Stainless Steel Sheet
• Metallic Mirrors and Precision Metal Polishing
• Acrylic Sheet, Aircraft Windows and Canopies
• Contact Lenses
• Superhard and Soft Nanoabrasives
• Polishing of PC Hard Disc
More advanced nano devices in use or
being developed: nanosensors for medical
use
DNA Chip
http://www.plasmachem.com
Bio-assay via Raman scattering:
http://www.oxonica.com/biodiag2.htm
Fluorescent nanocrystals for medical diagnostics:
http://www.oxonica.com/biodiag1.htm
Carbon nanotubes to monitor changes in breathing
http://www.nature.com/news/2004/041108//full/041108-18.html
Some other nanotechnology applications:
Lotus leaf effect
Gecko tape (van der Waals forces controlled ! )
etc.
Hydrophobic surfaces – based on “Lotus leaf principle”
Some existing applications of lotus effect surface treatment.
Stain resistant clothing from “NanoTex” fabrics
Gecko Tape.
Production of color by precise control of nanoscale structure – as in a butterfly
wing.
“Quantum Dots” - CdSe of precisely controlled particle size.
CdSe is a semiconductor and restricting the size of the particles to
nano dimensions also confines the conduction band electrons. The
fluorescent wavelength can be precisely controlled. This has gone from
lab discovery to commercial production in about a decade.
Another type of Nanotechnology: modifying natural
nanoscale systems.
Modifying DNA:
● Making artificial genes
● Creating new letters for genetic alphabet (to add to natural CTGA)
Making a “minimum living organism”:
Removing genes from a cell, one by one, to find the smallest set of genes with
which the cell can still live.
Creating a living cell entirely from non living starting
materials
More complex systems: Nano-machines
DNA replication is a natural “machine” at the nanoscale.
The DNA double helix is unwound, then the CTGA bases in
each strand are paired with their complements to form two
new double helix lengths of DNA – each an exact copy of
the original.
Movies of DNA replication
nature’s nanomachinery
(Internet link required )
Inorganic machines.
Nanoscale machines can be made that are not based on the
chemicals in living things. They might be copies of large scale
machines such as electric motors and contain familiar parts such as
roller bearings.
Nothing like this exists in nature.
Materials built from small units like this might be very useful. Living
cells in animals and plants have parts that have evolved to extract
energy (from sunlight, from glucose etc) and essentially just build new
cells.
Imagine copying the complexity of organisms but replacing the living
cells with nano scale motors, gears etc and with energy extracted
from sunlight, or heat or a suitable fuel, and designed to produce
almost anything we can imagine rather than just copies of themselves.
Building atom by atom opens enormous possibilities.
Many of these parts have been designed
Some have been produced:
This might seem very far fetched, but we know that even just the arrangement of
atoms has dramatic effects.
Carbon atoms arranged one way form diamond
Arranged another way they form
graphite
And in another arrangement
they form charcoal
If we use more than one type of atom the possibilities are
increased.
We know that living things are made up of many interacting tiny parts, yet
they are made of a limited range of atoms, and have just a few basic
ways of obtaining energy.
Its hard to even imagine what might be made when we assemble things
atom by atom, without any of the limitations that we
see in living systems.
Nanotechnology means any technology we
devise that manipulates things about a billionth of
a metre in size.
There are lots of ways of doing this.
Some practical applications already exist, but we
are just at the beginning of the nanotechnology
age and we can’t even imagine all the possible
ways nanotechnology will be used - even in the
near future.
Animations of imagined nanotechnology factory
(broadband connection needed for movies, slide sets over dial-up connections)
Google Movie of nanotechnology production