Fiber optic sensors based on nanostructured materials

Fiber optic sensors have been developed taking advantage on the synergy between the properties of nanostructured materials and the ones that characterize an optical fiber. The mechanical properties of optical fiber introduce some restrictions to the techniques used for the deposition of materials. As an alternative to the classical deposition procedures, wet coating techniques have been successfully applied in these cases. The current chapter put emphasis on materials that can be incorporated using wet coating techniques. The first one presented is the multilayer based nanostructures: among the different alternatives, we have focused on materials prepared with the Layer-by-Layer technique. Another type of products used for the fabrication of optical fiber sensors is sol-gel matrices, which are made of silica, so that its optical properties are similar to the ones of an optical fiber. The other two described type of products have focused the attention of many researchers in the recent years. Firstly, materials with an enhanced selectivity are presented: the molecularly imprinted polymers (MIPs). Finally, sensors based on metallic nanolayers and particles are presented. All these materials and techniques have acquired a great importance in the field of optical fiber sensors due to their versatility and the good features that offer. Fiber optic sensors have been developed taking advantage on the synergy between the properties of nanostructured materials and the ones that characterize an optical fiber. In this chapter, four types of materials employed to develop this kind of devices will be described: multilayer nanostructures, sol-gel derived materials, molecularly imprinted polymers and metallic thin films and nanoparticles.