Abstract
Fiber structures based on the combination of abrupt tapers and fiber Bragg gratings are studied. Two situations are exploredin one, the taper is fabricated in the fiber region with a fiber Bragg grating; in the other, the taper is first fabricated followed by the fiber Bragg grating. It is shown that the first device presents the properties of a Fabry-Perot cavity and the other of a phase-shifted Bragg grating, where the phase shift is associated to the tapered fiber region. The sensing characteristics of these structures are studied, and it is shown that the temperature sensitivities are similar but with observable different responses to strain.

Abstract
Poly(amidoamine) dendrimers (generations 5 and 6) with amine termini were conjugated with peptides containing the arginine-glycine-aspartic acid (RGD) sequence having in view their application as gene delivery vectors. The idea behind the work was to take advantage of the cationic nature of dendrimers and of the integrin targeting capabilities of the RGD motif to improve gene delivery. Dendrimers were used as scaffolds for RGD clustering and, by controlling the number of peptides (4, 8, and 16) linked to each dendrimer, it was possible to evaluate the effect of RGD density on the gene delivery process. The new vectors were characterized in respect to their ability to neutralize and compact plasmid DNA (pDNA). The complexes formed by the vectors and pDNA were studied concerning their size, zeta potential, capacity of being internalized by cells and ability of transferring genes. Transfection efficiency was analyzed, first, by using a pDNA encoding for Enhanced Green Fluorescent Protein and Firefly Luciferase and, second, by using a pDNA encoding for Bone Morphogenetic Protein-2. Gene expression in mesenchymal stem cells was enhanced using the new vectors in comparison to native dendrimers and was shown to be dependent on the electrostatic interaction established between the dendrimer moiety and the cell surface, as well as on the RGD density of nanoclusters. The use of dendrimer scaffolds for RGD cluster formation is a new approach that can be extended beyond gene delivery applications, whenever RGD clustering is important for modulating cellular responses.

Abstract
In this work the authors first summarily describe the main topics that were the subject of their post-graduate activity in fiber sensing at the Applied Optics Group of University of Kent in the late 1980s and early 1990s. After their return to Porto, Portugal, the know-how acquired during their stay at Kent and the collaboration paths that followed between the University of Porto and University of Kent were instrumental in the start-up and progress of optical fiber sensing activity in Portugal. The main topics addressed in this field, the description of some of the relevant developments achieved in recent years, the present situation and the guidelines for the future research and development activity in Portugal in fiber sensing will be the core of this work. © 2011 University of Electronic Science and Technology of China and Springer-Verlag Berlin Heidelberg.

Abstract
The development of an interferometric optical fiber inclinometer is described in this paper. A weak tapered region is induced in a standard single mode fiber in the vicinity of the cleaved fiber tip, using a standard fusion splicer. In this situation an in-fiber Michelson interferometer is constructed that is sensitive to curvature applied in the tapered region. It is shown that depending on the angular range, fringe visibility and/or peak position depend strongly on the applied curvature enabling low cost dielectric inclinometer to be setup that is suitable for high voltage applications. It is presented an analysis of the sensor response by means of experimental measurements and manipulation of these experimental data through computational simulations. The results coming from the numerical simulations indicate a good performance of the sensor within range of angular variation between 3 and 6 degrees and 10 and 14 degrees. A low cost strategy to interrogate the response of sensor using electrically modulated fiber Bragg gratings, a photodetector and frequency analysis is described. The results presented by this electric interrogation technique show a good sensitivity in the range 3.5 to 5.5 degrees.

Abstract
Microstructured optical fibers (MOFs) have been widely studied owing to their potential for obtaining novel transmission, nonlinear and sensing characteristics. Sensing applications of MOFs cover various types of devices for measurements of different physical and specific chemical compounds in gases and liquids employing evanescent field techniques. Such fibers can also be used as active and passive elements in fiber-optic polarimetric and interferometric sensors. We present an in-line fiber modal interferometer fabricated in boron-doped highly birefringent microstructured fiber. The boron-doped region located in the middle of the core decreases the effective index of the fundamental mode and facilitates coupling between the fundamental and the first order mode. The coupling regions have the form of fiber narrowings fabricated using CO2 laser and are distant by a few millimeters. The spectral intensity at the sensor output is modulated only by intermodal interference produced by a short piece of fiber between the two coupling points. Moreover, as the fiber is highly birefringence, each pair of polarization modes produces its own intermodal fringes, which results in the contrast modulation of the overall interference signal observed at the fiber output, and provides an additional degree of freedom to measure simultaneously a pair of measurands.

Abstract
This work describes a large-core air-clad photonic crystal fibre-based sensing structure that is sensitive to refractive index, temperature and strain. The sensing head is based on multimodal interference, and relies on a single mode - large-core air-clad photonic crystal fibre - single mode fibre configuration. Using two distinct large-core air-clad PCF geometries it is possible to obtain an optical spectrum with two dominant loss bands, at wavelengths that have different sensitivities to physical parameters. This characteristic is explored to demonstrate a sensing head that permits the strain-temperature discrimination functionality. It is also shown the large-core air-clad photonic crystal fibre can be applied to implement a sensing head sensitive to the water refractive index changes induced by temperature variations.