Nanotechnology

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Nanotechnology

• Versatile Bottom-up Nanofabrication Technique
• Layer-by-Layer Assembly

Anuja Choubey 12-01-2007
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Introduction
Nanofabrication Techniques

• Top-down
• Photon based Nanolithography
• Electron Beam Lithography
• Focused Ion Beam Lithography
• Bottom-up
• Self Assembled Monolayers (SAMs)
• Block Copolymers
• Electrostatic Self-Assembly
• Layer-by-Layer Assembly (LBL)

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Background

• Langmuir-Blodgett (LB)
• Expensive instrumentation
• Not applicable for non-amphiphilic materials
• Self assembled Monolayer (SAM)
• Not suitable for multilayer fabrication
• Layer-by-Layer Assembly (LBL)
• Inexpensive
• Simple, Easy-to-use
• Enhanced modularity
• Potential for greater versatility

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How LBL works?
Ariga et al., Phys. Chem. Chem. Phys., 9
(23192340), 2007
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Materials Used

• Polyions- PAH, PDDA, PSS, PVS, PAA, PPV
• Proteins, DNA, Charged polysaccharides
• Charged inorganic substances
• Colloidal nanoparticles
• Clay
• Nanosheets
• Modified zeolite crystals.
• Charged supramolecular assemblies
• Bolaamphiphile monolayers
• Lipid bilayers
• LB films
• Stacked dye molecules

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Characterization

• Microscopy
• AFM
• TEM
• SEM
• Optical Spectroscopy
• Ellipsometry
• Quartz Crystal Microbalance (QCM)

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Ellipsometry
Quartz Crystal Microbalance
A. Tronin et al., Colloid Polym. Sci., 272, 1317,
1994
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Applications

• Anti-static coating for plastics
• Sensors
• Oxygen sensor
• Glucose biosensor
• Light emitting diode
• Fuel Cells
• Polymer Capsules
• Micro-reactors
• Targeted Drug delivery

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Fuel Cell Application

http//web.mit.edu/hammond/lab/ashcraft.htmhttp/
/en.wikipedia.org/wiki/ImageFuel_cell_still.gif
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Formation of Polymer Capsules
E.Donath et al., Angew. Chem. Int. Ed. 37,
16(2202-2205), 1998www.coes.latech.edu/bme/resear
ch/reu/layer20by20layer20assembly.htm
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Limitations

• Fuzzy internal architecture
• Sensitive to working conditions
• Humidity
• Drying between cycles

Future Work

• Synergy with other techniques
• Top-down microfabrication

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• Questions?