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Nanotechnology

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

~ Anuja Choubey

12-01-2007

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Introduction

“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)

Nanofabrication Techniques

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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 (2319–2340), 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

A. Tronin et al., Colloid Polym. Sci., 272, 1317, 1994

Quartz Crystal Microbalance

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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/Image:Fuel_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/research/reu/layer%20by%20layer%20assembly.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?