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Nanotechnology. Versatile Bottom-up Nanofabrication Technique: Layer-by-Layer Assembly. ~ Anuja Choubey 12-01-2007. Introduction. Nanofabrication Techniques. “Top-down” Photon based Nanolithography Electron Beam Lithography Focused Ion Beam Lithography “Bottom-up”
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Nanotechnology Versatile Bottom-up Nanofabrication Technique: Layer-by-Layer Assembly ~ Anuja Choubey 12-01-2007
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)
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
How LBL works? Ariga et al., Phys. Chem. Chem. Phys., 9 (2319–2340), 2007
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
Characterization • Microscopy • AFM • TEM • SEM • Optical Spectroscopy • Ellipsometry • Quartz Crystal Microbalance (QCM)
Ellipsometry Quartz Crystal Microbalance A. Tronin et al., Colloid Polym. Sci., 272, 1317, 1994
Applications • Anti-static coating for plastics • Sensors • Oxygen sensor • Glucose biosensor • Light emitting diode • Fuel Cells • Polymer Capsules • Micro-reactors • Targeted Drug delivery
Fuel Cell Application http://web.mit.edu/hammond/lab/ashcraft.htmhttp://en.wikipedia.org/wiki/Image:Fuel_cell_still.gif
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
Limitations • Fuzzy internal architecture • Sensitive to working conditions • Humidity • Drying between cycles Future Work • Synergy with other techniques • Top-down microfabrication