Abstract
CdTe quantum dots (QDs), capped with mercaptopropionic acid (MPA), were synthesized and the variation of their fluorescence properties (steady state and lifetime)with pH was assessed in solution and when immobilized in a sol-gel host Three different sizes of CdTe QDs with excited state lifetimes ranging from 42 to 48 ns and with emission maximum at 540 nm (QD(540)). 580 nm (QD(580)) and 625 nm (QD(625)) were selected The solution pH affects the maximum emission wavelength (shifts to higher wavelengths of 23, 24 and 27 nm for QD(540), QD(550) and QP(625), respectively), the excited state lifetime and the fluorescence intensity in a reversible way. Linearization of the maximum emission wavelength variation with the pH allows the estimation of an apparent ionization constant (pK(a)) for each QD: 6.5 +/- 0.1 (QD(540)), 6.1 +/- 0.5 (QD(580)) and 5.4 +/- 0.3 (QD(625)) The variation of the QDs fluorescence properties was further explored using confocal laser scanning microscopy allowing the implementation of a new calibration method for pH imaging in solution QDs were successfully immobilized on the tip of an optical fiber by dip-coating using sal-gel procedure The immobilized QDs showed a similar pH behaviour to the one observed in solution and an apparent lifetime of 80,68 and 99 ns, respectively. The proposed QDs based methodology can be successfully used to monitor pH using wavelength encoded data in imaging and fiber optic sensing applications.

Abstract
The deterioration of water quality by Cyanobacteria causes outbreaks and epidemics associated with harmful diseases in Humans and animals because of the released toxins. Microcystin-LR (mcyst) is one of the most widely studied hepatotoxin and World Health Organization recommends a maximum value of 1 mu g L-1 of mcyst in drinking-water. Therefore, there is a great demand for remote, real-time sensing techniques to detect and quantify the presence of mcyst. In this work a Fabry-Perot sensing probe based on a fibre tip coated with a mcyst sensitive thin film is presented. Highly specific recognition membranes, using sol-gel based Molecular Imprinted Polymers (MIPs), were developed to quantify microcystins in water, showing great potential in the analysis of this kind of samples. The fibre Fabry-Perot MIP sensor shows a linear response to mcyst concentration with a sensitivity of -13.2 +/- 0.4 nm L mu g(-1).

Abstract
An intrinsic Fabry-Perot cavity for high temperature and strain measurement is presented. The in-fibre cavity is formed by a chemical etched graded index optical fiber spliced to a single mode fiber. The intrinsic sensor obtained shows high sensitivity to strain (6.2 pm/mu epsilon) and rather low sensitivity to temperature (0.9 pm/degrees C), being suitable for applications as a strain gauge at high temperature.

Abstract
A technique for the fabrication of luminescence based fiber optic optrodes with multiple analyte sensitivity is proposed. Combination of photosensitive polymers doped with different luminescent indicators was used to produce fiber probes, by self-guiding photopolymerization, having different geometries and sensing capabilities. Results demonstrating the method flexibility are shown with luminescent probes doped with CdSe/ZnS quantum dots and an organometalic ruthenium complex for simultaneous detection of oxygen and temperature.

Abstract
The implementation of refractometric based fiber optic sensors for environmental monitoring is discussed. Several sensing head configurations and interrogation schemes are presented and compared in the framework of different biochemical sensing applications. Results are presented demonstrating the suitability of this technology to monitor a diversity of chemical and biological parameters of environmental significance.

Abstract
In this work it is presented a system to control a self-referencing fiber optic intensity displacement sensor using virtual instrumentation. To ensure higher flexibility and dynamic optimization, the use of an optical fiber delay line or an electrical delay line is avoided by implementing a delay line in the virtual domain, preserving the self-referencing and sensitivity characteristics of the proposed optical intensity sensing structure.