PHOSFOS (Photonic Skins For Optical Sensing) is a research project funded by the European Commission's 7th
Framework Programme. The project aims at developing a flexible and stretchable foil that integrates highly advanced
optical fibre sensing elements as well as optical and electrical powering functionalities and read-out of the sensors. This
skin-like foil can be wrapped around or attached to irregularly shaped objects or bodies and will allow quasi-distributed
sensing of mechanical quantities such as deformation and pressure. The applications targeted can be found in the fields
of structural health monitoring and healthcare.
In the paper the results of ORMOSIL gels' structures' investigation were presented. As a method XRD (X-ray
diffraction) was applied. ORMOSIL gels comprising phenyl and methyl groups may be used as matrices for active layers
in optical fibre sensors because an organic dye acting as a transducer may be easily introduced into their network during
a so-called sol-gel process. Moreover, the refractive index of such layers may be modified by changing a molar ratio of
different alkoxysilanes in a sol. As a signal of an UV optical fibre sensor strongly depends on sols' composition and
ageing time it could be suggested that the structure of the gel may influence the behaviour of the dye. XRD method
enables determining positions and distances between molecules, positions of atoms, angles' and bonds' lengths between
atoms, distribution of electron's cloud's density on atoms, dipole moment of bonds and molecules as well as the nature
of bonds, therefore it may be useful in examination of the structure of partially ordered elementary cell of the gel. The
results may help to understand dependence between the structure of the gel and sensor's signal's value and lead to
achieve a better performance of the optical fibre UV sensor.
The paper concerns the results of ORMOSIL layer's applied in an optical fibre ultraviolet sensor Nuclear Magnetic
Resonance investigation. The layer which substituted for optical fibre's cladding in device's sensing part acted as a
matrix for a coumarin's derivative. The dye is able to convert ultraviolet into visible radiation which could be easily
detected. Thanks to the fact that the refractive indices of ORMOSIL layers may be controlled and reach a value
characteristic for the fused silica glass a satisfying sensitivity of the device can be achieved. However it may be expected
that both the structure and the composition of ORMOSIL matrices could influence the organic dye's behaviour. The aim
of the experiment presented in the paper was to prove a relation between the sol's condensation time and a composition
of the obtained gel's structure. The obtained NMR spectra gave the evidence of non-condensed -Si-O-C2H5(H) moieties
existence in the solid gels. Moreover, even a 42-days-long process does not lead to the total condensation of
ethoxysilanes' molecules. It is probable that the remaining ethoxy or silanol groups interact with transducer's molecules
as well as influence the refractive index of the gel layer.
The paper concerns the results of optical fibre's ultraviolet sensors' investigation. The cladding of the optical fibre's sensing part was removed and substituted with an active layer containing a coumarin's derivative designated with the number 3609. The dye acted as a transducer converting ultraviolet into visible radiation which could be easily detected. The theoretical modeling with the use of genetic algorithms proved that the best sensitivity of the sensor is achieved when the refractive indices of the active layer and the core are equal. Organically Modified Silica (ORMOSIL) matrices satisfy that condition as their refractive indices may be controlled and reach a value characteristic for the fused silica glass. However it may be expected that both the structure and the composition of ORMOSIL matrices may influence the organic dye's behaviour. The aim of the experiment presented in the paper was to measure the sensitivity of optical fibre sensors comprising the active layers composed of three alkoxysilanes which were methyltriethoxysilane (MTES), phenyltriethoxysilane (PhTES) and tetraethoxysilane (TEOS) as far as the sensitivity of the sensors with silica active layer derived from pure TEOS. Moreover, the influence of hydrolysis and condensation's time on the intensity of dye's luminescence both in active layers and sols' solutions was investigated. The results proved that hydrolysis time and gel's composition may influence a sensitivity of the sensor. Despite the initial decrease of luminescence's signal the long-lasting stability of UV/VIS conversion has been noticed which creates a possibility of the future practical application of the described sensors.
In the paper the preliminary results of the investigation on the possible application of the photo-curable hybrid material
synthesis for either optical fibres' protective coatings or UV-VIS transducers' (luminophores in optical fibres' UV
sensors) matrices have been described. As the initial synthesis materials the sol-gel silica and UV-curable polyglycols'
acrylates have been used. The results of the organic-inorganic polymers' photopolymerization process investigation as
well as the properties of the obtained materials have been presented.
In the paper the preliminary results of the new UV-curable polymer designed for a luminophores' matrix application in the optical fibres' optical sensor investigations have been presented. The conditions of the monomer's photopolymerization, the refractive index of the obtained polymer and its mechanical properties have been examined.
The paper concerns the investigation of modified silica gel materials applied in optical fibre sensors. These materials are products of a sol-gel process in which three kinds of alkoxysilanes undergo hydrolysis and condensation and may play a role of the matrices containing transducer's molecules in the active layer of the sensor. In the experiment presented below three different compositions comprising tetraethoxysilane (TEOS), methyltriethoxysilane (MTES) and phenyltriethoxysilane (PhTES) were used. The alkoxysilanes underwent hydrolysis and condensation and the obtained gels were investigated in order to determine their texture, strucuture, composition and chemical properties as far as the dependence of those characteristics on the hydrolysis time and the molar ratio of the ingredients in the initial sols. The methods employed in the experiment were: Atomic Force Microscopy (AFM) which delivered vital information about the gels' textures, contact angles' and surface charge's measurements serving to estimate chemical properties of the gels' surfaces, Nuclear Magnetic Resonance (NMR) which helped to evaluate the hydrolysis' rate and porosimetric measurements enabling a determination of BET surface area and average diametres of the pores. The results may occur important for improving the construction of optical fibre sensors in which organically modified silicates (ORMOSILs)-TEOS layes are used.
In this paper a project of a simple optical fibre ultraviolet sensor was presented. As the main part of the sensor, the
active layer containing an organic dye able to absorb ultraviolet radiation and afterwards emit radiation in a visible
range underwent the detailed investigation. The Atomic Force Microscopy (AFM) images of the gel active layers
clearly proved a relation between the surface structure, time of sol's hydrolysis and the compositions of the sols which
differed with the molar ratio of three alkoxysilanes (TEOS- tetraethoxysilane, MTES- methyltriethoxysilane and
PhTES- phenyltriethoxysilane). The experiment was being carried out during 42 days with the measurements every 7th
day. Additionaly, a dependence between the structure of the examined surface (which means also a dependence of both
remaining factors mentioned above) and emission's intensity of the sensor while excitated with a banknote-control UV
standard lamp has been noticed. The obtained results give an obvious prove the optical properties of UV optical fibres'
sensor in which a gel active layer is applied depend on many different factors, which adequately matched may result in
a big sensitivity and efficiency of such a sensor.
In the paper some properties of optical fibers coatings applied in the chemical and biochemical sensors are presented. The special attention was focused to the surface properties and structure of sol-gel layers, but also the features of the polymer coatings are described.
In the paper simple genetic algorithm (SGA) as well as its modifications were applied for optimization of an optical fiber UV sensor construction. Influence of the algorithm parameters i.e. the population size, the probability of crossover and mutation from the point of view of algorithm efficiency is discussed herein.
In the paper the results of investigation of luminescence properties of the coumarine derivative used as an optical UV/VIS transducer in the optical fiber UV sensor are presented. It was found that this compound probably chemically reacts with the polymer matrix in which was dissolved. The arising compound reveals luminescence properties other than initial coumarin derivative and is highly photostable.
In the paper the hybrid optical fibre pH sensor based on absorption and refraction is presented. As an optical transducer pH-sensitive metyl orange dye was exploited. Additionally, variations of the refractive index of the porous silica film with the pH of solution were also utilized. The film, in which the dye was encapsulated, was prepared by means of the sol-gel method and deposited onto the fibre core. It was found that the sensitivity for acidic (2÷6) and basic (7÷10) ranges were 1,0 dB/pH and 3,5 dB/pH, respectively.
We are using UV-cured polymers as protective coatings of optical fibers. Protective coatings use hermetic materials such as: diamond-like carbon, Si3N4 and metal layers too. This work presents a new method of producing thin silver layers on optical fibers in their production.
The probe for the copper ions detection was investigated. As an optical transducer porphyrines were used H4TPPS4 and cationic H2TMePyP. The porphyrines were entrapped in a sol-gel film deposited directly on optical fiber core. The performance of the oprtodes was tested. The influence of the response time on gelation conditions of the sol-gel matrix was also investigated.
The influence of surface properties of sol-gel derived silica on pH sensing is presented. It is observed that the surface charge of silica, caused by pH change, leads to absorption of cations on the porous silica surface. As a consequence, one can observed an increase of refractinve index of the sol-gel material, hence, its optical properties and light propagation conditions. Since the effect is pH-dependent and its magnitude is so strong, it can even be exploited for pH sensing. Theoretical considerations correlate with results of surface charge and optical properties of a model of pH sensor measurements.
The goal of this work was to construct an optical fibre with a thick core made from multicomponent glass and a thin cladding made from quartz glass. The method to calculate durability of such an optical fibre has been worked out. The fibres with cores from commercially accessible multicomponent technical glasses have been prepared. Partial agreement of quantitative theoretical description with the experimental data has been obtained. Durable structures of optical fibres with numerical aperture of 0.35 have been produced from pyrex glass (core) and quartz glass (cladding).
The paper describes an evanescent wave sensor model operating far from the modal steady state. Assuming that of the numerical aperture varies exponentially with the fibre length and the light losses are proportional to the local and fibre numerical apertures ratio, the sensor description was evaluated. Experiments, in which the sensor absorbance versus the refractive index of the medium surrounding the fibre core and the fibre sensing section length, were made to confirm the theoretical model of the sensor and good agreement was observed.
The evanescent wave optical fibre probe for Cu2+ ions detection was elaborated. As an optical transducer a porphrine (H2TMePvP) was used. The detection limit of the probe as evaluated to be 5x10-5 mol/1 (3ppm).
The present work is concerned with the optical characterization of an evanescent wave sensor for pH detection. First, the interaction between the solution containing the acid-base indicator and the fiber core was investigated. Then, the acid-base indicator, thymol blue, was covalently immobilized on the core of a 200/380 micrometers fiber by means of a silylation process of the glass surface. The fiber core surface was modified along a section of 8 mm. A comparison was made using both bare and tapered fibers, with a tapering ratio (fiber diameter/waist diameter) of 2.3. An enhancement in sensitivity of a factor 6 was observed with tapered fibers in the 1/2.5 range, and a sensitivity of 0.05 pH units was attained.
Many properties of optical fibers, particularly their mechanical strength and resistance to water corrosion depend on the adhesion of their protective coatings to the glass part of the fiber. Therefore, the protective coatings materials providing high adhesion should be applied for optical fiber construction. It is possible to predict the value of the adhesion energy from the properties of the surfaces being in contact. The paper presents the application of inverse gas chromatography to determine these properties.
The effect of optical fiber polymer coatings on the mechanical properties of a fiber was studied. Their adhesion to the optical fiber surface is of special interest. It is also shown how the analysis of electron donor and electron acceptor properties of the surfaces being in contact can predict the adhesion energy. An optical fiber model taking into consideration the pressure exerted on it by the protective coating is also described.
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