The electrostatic layer-by-layer (LbL) self-assembly of polyelectrolyte’s has shown applications in thin film coatings, micro patterning, nano-bioreactors and capsules for drug delivery. The film architecture can be precisely designed and controlled to nanometer scale precision with a range from 5 nm to a few microns. Both in vitro and in vivo studies indicate potential applications in biology, pharmaceutics, medicine, and other biomedical areas. This thesis work focused on the design and development of protocols to fabricate polyelectrolyte multi-layer patterns on a variety of substrates such as glass, metals and plastics such as acrylic and polycarbonate. The micro-scale polyelectrolyte patterns have applications in the creation of DNA, protein or cell based microarrays. This work also demonstrated the use of polyelectrolyte multi-layers in the enhancement of fluorescence signals from fluorophore-tagged molecules captured within the multi-layers. In-situ measurements using Fiber Bragg Gratings were carried out to study the kinetics of adsorption and desorption of polyelectrolytes participating in the layer buildup process under different process environmental conditions.

In this thesis work, a systematic quantitative study has been undertaken, on the performance of etched fiber Bragg Grating (FBG) sensors in the investigation of surface molecular adsorption in real-time; it is shown that the limit of detection (LOD) of FBGs etched below 2 microns diameter, is better compared to prominent optical label-free molecular sensing techniques such as Surface Plasmon Resonance (SPR). Novel fiber optic sensors based on FBG and etched FBG with various nano materials (polyelectrolytes, carbon nanotubes, hydrogel, metals and chalcogenides) coated on the surface of the core or cladding, have been proposed for sensing multi parameters such as pH, protein, humidity, gas, strain, temperature, and light etc. Besides being reproducible and repeatable, the proposed methods are fast, compact, and highly sensitive. A novel optical instrument has also been developed to measure angular deviation, binocular deviation and refractive index of glass slabs, and liquids, based on a shadow casting technique. This method uses the deviation in the geometrical shadow cast by a periodic dot pattern trans-illuminated by a distorted light beam from the transparent test specimen relative to a reference pattern.