Transcript Nano - Denise Kapler

Nano
Slow-Releasing Nanoburrs
From herbal tea
Honeybee's two compound eyes
Up Close With Your Tongue
Sugar
Single layer of graphene
Pollen
What's Measured Gets Managed.
What do you measure?
Common Unit Conversions used in
Nanoscience
1 m = 100 cm
1 m = 1,000 mm
1 m = 1,000,000 μm = 106 μm
1 m = 1,000,000,000 nm = 109 nm
1 m = 10,000,000,000 Å = 1010 Å
1 cm = 107 nm
1 cm = 108 Å
1 mm = 1,000 μm
nm – measure atomic structure
1 μm = 1,000 nm
Å – measure light waves
1 μm = 10,000 Å
FNI 1B
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One nanometer =
3 silicon atoms in a row
cm
inches
1
cm  5, 000, 000nm
2
1,000,000 nanometers
1 millimeter = 1,000,000 nanometers
IBM logo made up of 35 atoms of xenon on nickel
17 nanometres long and was made with a scanning tunnelling microscope in 1986
Spider’s Skin
Human Hair with Lice
The tree-like structures in this scanning electron microscope image of a cross section of
a butterfly wing are on the undersides of the Morpho's wing scale ridges. These
microribs reflect light to create iridescent colors. The Blue Morpho is common in Central
and South America and known for its bright blue wings. However, these iridescent
colors are created not by pigments in the wing tissues but instead by the way light
interacts with nanometer-sized structures on the Morpho's wing scales. This effect is
being studied as a model in the development of new fabrics, dye-free paints, and anticounterfeit technologies for currency.
Structure of butterfly wing
Based on this discovery of butterflies wing structure, engineers are developing single
sensors that are tailored to detect certain types of chemical agents or explosives. These
sensors light up when they encounter threats.
Small, smaller, "nano" data storage!
Metallofullerene Model
80 carbon atoms (light blue)
3 dysprosium atoms (red)
1 nitrogen atom (dark blue)
Small, smaller, "nano" transport of very small
Nanotube
T4 Bacteriophage - a virus
Your Brain
1. There are approximately 50,000,000 neurons per square centimeter (50X106 per cm3)
2. Each cm3 neurons have axons that reach out to create 1 trillion synapse (1×1012)
3. If each synapse can express 8 bits or 1 byte of information, than 1 cm3 contains 1
terabyte of data (1×1012)
4. The human brain is roughly 1000 cm3 in size which means it can store about 1 petabyte
of data (1×1015)
5. That is about 1/3 as much data as stored in the entire internet … in one average
human brain.
So when will a computer the size of a brain match its capacity?
By current rates of change it looks like we will be there between 2025 and 2030.
Brain Cell – Soma and Dendrites
Snail neuron grown on a chip that records the neuron’s activity
Properties of a Material
• A property describes how a material
acts under certain conditions
• Types of properties
–
–
–
–
Optical (e.g. color, transparency)
Electrical (e.g. conductivity)
Physical (e.g. hardness, melting point)
Chemical (e.g. reactivity, reaction rates)
• Properties are usually measured by
looking at large (~1023) aggregations of
atoms or molecules
Sources:32http://www.bc.pitt.edu/prism/prism-logo.gif
http://www.physics.umd.edu/lecdem/outreach/QOTW/pics/k3-06.gif
Optical Properties Change:
Color of Gold
• Bulk gold appears yellow in color
• Nanosized gold appears red in color
– The particles are so small that electrons are not
free to move about as in bulk gold
– Because this movement is restricted, the
particles react differently with light
“Bulk” gold looks yellow
12 nanometer gold clusters of particles
look red
Sources:33http://www.sharps-jewellers.co.uk/rings/images/bien-hccncsq5.jpg
http://www.foresight.org/Conferences/MNT7/Abstracts/Levi/
Electrical Properties Change:
Conductivity of Nanotubes
• Nanotubes - long, thin cylinders of carbon
– 100 times stronger than steel, very flexible,
– unique electrical properties
• Their electrical properties change with diameter, “twist”, and
number of walls
– either conducting or semi-conducting in their electrical
behavior
Electric
current varies
by tube
structure
Multi-walled
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Source: http://www.weizmann.ac.il/chemphys/kral/nano2.jpg
Physical Properties Change:
Melting Point of a Substance
• Melting Point (Microscopic Definition)
– Temperature at which the atoms, ions, or
molecules in a substance have enough energy
to overcome the intermolecular forces that
hold the them in a “fixed” position in a solid
Surface atoms require less energy
to move because they are in contact
with fewer atoms of the substance
In contact with 3 atoms
In contact with 7 atoms
Sources:35http://puffernet.tripod.com/thermometer.jpg and
image adapted from http://serc.carleton.edu/usingdata/nasaimages/index4.html
Physical Properties Example:
Substance’s Melting Point II
At the macroscale
At the nanoscale
The majority of
the atoms are…
…almost all on the inside
of the object
…split between the inside
and the surface of the
object
Changing an
object’s size…
…has a very small effect
on the percentage of
atoms on the surface
…has a big effect on the
percentage of atoms on the
surface
The melting
point…
…doesn’t depend on size
… is lower for smaller
particles
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Size Dependant Properties
Why do properties change?
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Scale Changes Everything
• There are enormous
scale differences in
our universe!
• At different scales
– Different forces
dominate
– Different models
better explain
phenomena
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Scale Changes Everything II
• Four important ways in which nanoscale
materials may differ from macroscale materials
– Gravitational forces become negligible and
electromagnetic forces dominate
– Quantum mechanics is the model used to describe
motion and energy instead of the classical mechanics
model
– Greater surface to volume ratios
– Random molecular motion becomes more important
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Dominance of Electromagnetic Forces
• Because the mass of nanoscale objects is so
small, gravity becomes negligible
– Gravitational force is a function of
mass and distance and is weak
between (low-mass) nanosized particles
– Electromagnetic force is a function of
charge and distance is not affected by
mass, so it can be very strong even
when we have nanosized particles
– The electromagnetic force between two
protons is 1036 times stronger than the
gravitational force!
Sources:40http://www.physics.hku.hk/~nature/CD/regular_e/lectures/images/chap04/newtonlaw.jpg
http://www.antonine-education.co.uk/Physics_AS/Module_1/Topic_5/em_force.jpg
Quantum Effects
• Classical mechanical models that we
use to understand matter at the
macroscale break down for…
– The very small (nanoscale)
– The very fast (near the speed of light)
• Quantum mechanics better
describes phenomena that classical
physics cannot, like…
– The colors of nanogold
– The probability (instead of certainty)
of where an electron will be found
Sources:41http://www.phys.ufl.edu/~tschoy/photos/CherryBlossom/CherryBlossom.html
http://www.nbi.dk/~pmhansen/gold_trap.ht; http://www.sharps-jewellers.co.uk/rings/images/bien-hccncsq5.jpg;
Macrogold
Nanogold
Surface to Volume Ratio Increases
• As surface to volume ratio
increases
– A greater amount of a
substance comes in contact
with surrounding material
– This results in better
catalysts, since a greater
proportion of
the material is exposed
for potential reaction
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Source: http://www.uwgb.edu/dutchs/GRAPHIC0/GEOMORPH/SurfaceVol0.gif
Random Molecular Motion is Significant
• Tiny particles (like dust) move
about randomly
– At the macroscale, we barely see
movement, or why it moves
– At the nanoscale, the particle is
moving wildly, batted about by
smaller particles
• Analogy
– Imagine a huge (10 meter) balloon being batted about
by the crowd in a stadium. From an airplane, you barely
see movement or people hitting it; close up you see the
balloon moving wildly.
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Source: http://www.ap.stmarys.ca/demos/content/thermodynamics/brownian_motion/rand_path.gif