Abstract
As optical fibers revolutionize the way data is carried in telecommunications, the same is happening in the world of sensing. Fiber-optic sensors (FOS) rely on the principle of changing the properties of light that propagate in the fiber due to the effect of a specific physical or chemical parameter. We demonstrate the potentialities of this sensing concept to assess pressure in biomedical and biomechanical applications. FOSs are introduced after an overview of conventional sensors that are being used in the field. Pointing out their limitations, particularly as minimally invasive sensors, is also the starting point to argue FOSs are an alternative or a substitution technology. Even so, this technology will be more or less effective depending on the efforts to present more affordable turnkey solutions and peer-reviewed papers reporting in vivo experiments and clinical trials. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. [DOI: 10.1117/1.JBO.18.5.050903]

Abstract
An analytical model based on geometrical optics and multilayer transfer matrix method is applied to determine the sensing properties of tapered optical fiber based SPR sensors incorporating bimetallic (Gold and Silver) layers, particularly when phase interrogation is considered. Phase interrogation is studied as a methodology to attain enhanced sensitivities. The performance of the sensing heads as function of the bimetallic layers and taper parameters is analyzed. It is shown the bimetallic combination is capable to provide larger values of sensitivity compared with the single layer approach. The results derived from this study are guiding the experimental study of these structures.

Abstract
A vibration sensor based on a distributed Bragg reflector (DBR) is proposed. The gratings that form the cavity are written in erbium-doped fibre using the femtosecond laser technique. In this configuration, one grating of the DBR acts as a sensor whilst the other one acts as a spectral filter. The active sensor, subjected to vibration measurements, exhibits a response of up to similar to 1.5 kHz.

Abstract
A torsion active sensor based on a figure-of-eight configuration is presented. The interferometric fiber loop mirror, composed by a section of photonic crystal fiber, also acts as a sensing element. When torsion is applied over a range of 180 degrees, a sensitivity of 7.13 pm/degree is achieved. Besides, this configuration can also be used to measure optical power variations and it presents low sensitivity to temperature.

Abstract
In this work, we present a method to predict the behaviour of a remote optical fiber sensor system based on a long period grating, Raman amplification and electrical interrogation were investigated. The interrogation unit is composed by two fiber Bragg gratings modulated by two piezoelectrics transductors. Optical fiber sensor systems are typically limited to operate at distances of only few kilometers due to the attenuation effects and noise that adversely affects the performance of the sensor interrogation process. We present experimental and simulation results obtained in the context of analysis of remote optical fiber sensors. The simulation models use numerical methods to compute the Raman interaction between the pumps and the sensor signals and allow speeding up the analyses regarding the setup to be experimentally implemented to measure environmental temperature. The results obtained show that under Raman amplification the power ratio between the two central wavelengths of the FBGs has a linear relation with the change of the LPG resonance induced by temperature variation.

Abstract
An analytical model based on geometrical optics and multilayer transfer matrix method is applied to the surface plasmonic resonance supported by fibre taper structures in the context of optical sensing applications. Phase interrogation is considered in particular as a methodology to attain enhanced sensitivities, and the performance of the sensing heads as function of the metal clad and taper parameters is analyzed. General topics concerning the actual relevance of plasmonics are also presented, first in a global perspective and then when applied to sensing.