A journey into the nanoworld

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A journey into the nanoworld

• Neil Bennett

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Outline

• What is nanotechnology and why do we want it?
• The big idea molecular electronics
• How do we see nanoscale objects
• My work
• Nanobots
• Grey goo

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Some revision

• What does nano mean again?

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Length scales
Pentium 4 feature size
White blood cell
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What is nanotechnology?

• lt 100nm
• Multidisciplinary
• New materials, electronic devices, mechanical
  devices, health treatments
• Nanostructures influenced by quantum mechanics

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Ok, so whats quantum mechanics?

• Small objects behave as both waves and particles
• Exist in quantised states
• See Schrödinger's cat

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Nano-myths
Nanotechnology is a "science project" whose
commercial products will only emerge some years
in the future.

• Nano-facts
• Currently more than 370 products on the market
  utilizing nanotechnology.
• These range from car tires and sports equipment
  to electronics, clothing, and cosmetics.
• Market worth over 32 billion in 2005.

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Why do we need nanoscale science?

• Things just keep getting smaller
• Soon devices will too small to fabricate with
  current methods

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The big idea molecular electronics

• Perhaps we could make a transistor out of
  molecules
• Two questions
• How do you make it?
• How will it function?

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How do we make nano-devices?

• Top-down
• Lithography - limited by wavelength of light (a
  few hundred nm)
• X-rays, Electron or Ion beams can be used instead
  giving 50nm features
• Bottom-up
• Molecular self assembly
• Biological recognition

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Focused ion beam

• Material can be deposited or etched away with
  high resolution

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Sophisticated self assembly

• Can structures be designed and self-assembled?
• The different strands are made by genetic
  engineering approaches.
• Good potential for future.

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Nanotechnology in action Tuneable photonic
crystals

• Colour depends on magnetic field strength

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Seeing on the nanoscale

• How do we see below the diffraction limit?
• X-ray diffraction
• Electron microscope
• Scanning probe techniques

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X-ray diffraction large molecules
X-ray diffraction was used to resolve DNA
Structure!
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Electron microscopes
Carbon nanotubes
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Whats that supposed to be?
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Whats that supposed to be?
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Whats that supposed to be?
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Scanning probes

• Use a sharp probe to sense objects

• Scanning tunnelling microscope (STM)
• Electrical current

• Atomic force microscope (AFM)
• Forces

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Atomic manipulation - STM

• Move individual atoms with the probe tip
• Interesting effects
• but time consuming

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AFM Atomic force microscopy

• Oscillating probe feels forces
• Simple harmonic motion pendulum!
• Sharp tip enables nanometre resolution

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Some images

• Silicon atoms imaged by STM
• Surface of sample must be very clean to image
  single atoms!

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Some images

• Virus particles imaged by AFM
• Biological samples are very soft must take care
  not to damage whilst imaging

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Some images
Polymer Network

• Electrical potential of a Polymer network
• Imaged by Electrostatic force microscopy

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My work
Scanning probe microscope
Me
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My work

• Nano-fishing
• Pick up molecules with probe tip

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molecule
Metal surface atoms
Artists impression not to scale
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My work

• Nano-fishing
• Pick up molecules with probe tip
• Measure electrical current through the molecule
• Effect of temperature, length, chemistry,
  environment

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Nanobots

• Robots with nanoscale components
• Target cancer cells or radicals
• Build new technologies from the molecule upwards
• Self replicate?

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Grey Goo!
SELF-REPLICATING ROBOTS TAKE OVER THE WORLD!
Runaway replicators turn everything in their path
to grey goo!
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Real nanobots Life!

• Bolts, hinges and microchips?
• Nanobots might be more like living cells
• E.g. the bacterial flagellum
• Self assembled motor driven by electrical signals

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Nanotoxicity

• Real potential danger
• Effects on respiratory and nervous system unknown
• inert particles can still be dangerous
• think asbestos
• gold nano particles

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Conclusions

• Nano is the future!
• Nano is quirky
• Nano is invisible
• Nano is all around us
• and finally,
• Nano could damage your health, but dont worry
  about grey goo

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More info

• Scanning probes
• University of Bristol
• http//spm.phy.bris.ac.uk/
• Carbon nanotubes
• Cambridge University
• http//www-g.eng.cam.ac.uk/cnt/
• DNA nanostructures
• Professor Andrew Turberfield, University of
  Oxford http//www.bionanotechnology.ox.ac.uk/
• Nano-fishing
• Richard Nichols, Liverpool, http//pcwww.liv.ac.uk
  /nichols/

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Nanotech already in use

• New materials - Golf clubs!
• Sunscreens
• gel-based nanoscale catalysts
• OLED color screens (made of nanostructured
  polymer films)
• Quantum dot technologies
• Desired applications
• Strong, lightweight materials form nanotubes
  soon?....
• Solar powered Hydrogen extraction (fuel)
• Targeted chemotherapy - nano-caged drugs