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The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing material be loaded into a supporting matrix whose morphology is adjusted at a nanometric scale. Thanks to the advances in nanotechnology new deposition methods have been developed: they allow reagents from different chemical nature to be embedded into films with a thickness always below a few microns that also show a relevant aspect ratio to ensure a high transduction interface. This review reveals some of the main techniques that are currently been employed to develop this kind of sensors, describing in detail both the resulting supporting matrices as well as the sensing materials used. The main objective is to offer a general view of the state of the art to expose the main challenges and chances that this technology is facing currently. [ABSTRACT FROM AUTHOR]

Thanks to the peculiarities of optical fiber and its ability to be combined with nanotechnology, precise and accurate measurements of the changes in optical properties (i.e., refractive index) of the medium surrounding the fiber are becoming possible with a high degree of performance. Thus, optical fiber sensors (OFSs) are increasingly finding applications in biochemistry and biomedicine. Here, all types of optical fiber refractometers are covered, and they are classified into three main groups: interferometers, grating‐based structures, and resonance‐based structures (the resonance is induced by coating the optical fiber sensor with a thin film). The performance of these different structures is compared by means of the most common parameters: sensitivity, full width at half minimum or maximum, figure of merit, and quality factor. The aim here is to provide a reliable and easy‐to‐use tool to compare the performance of the most recent developments on fiber optic refractometers. [ABSTRACT FROM AUTHOR]

Here we show an optical refractometer with a giant sensitivity of 304,360 nm per refractive index unit (nm/RIU). This sensitivity corresponds to a resolution of 3.28 × 10 −9 RIU if a standard optical spectrum analyzer with a resolution of 1 pm is used. This record sensitivity is obtained by means of a lossy mode resonance (LMR) optical fiber sensor in a surrounding media with refractive index around 1.45. This achievement implies that the utilization of the LMR phenomenon opens the door to devices and systems that can beat, in terms of sensitivity, those used currently in real-time biomolecular analysis such as surface plasmon resonance (SPR) devices. [ABSTRACT FROM AUTHOR]