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Paixao T.,University of Aveiro | Araujo F.,FiberSensing | Ferreira L.,FiberSensing | Antunes P.,University of Aveiro | Antunes P.,Telecommunications Institute of Portugal
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

We report on a thermal stability study of the resonant wavelength of fiber Bragg gratings fabricated by femtosecond laser. We propose a new method to analyze the decay of the central wavelength shift of Bragg gratings based on isothermal and isochronal processes up-to a maximum temperature of 800°C. The obtained thermal decay follows a typical power-law function, which allowed us to fit theoretical equations to our experimental data and simulate the refractive index decay. A method to mitigate this decay is proposed and the results demonstrate the potential of using femtosecond fiber Bragg gratings as high temperature sensors. © 2017 SPIE.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-TP | Phase: NMP-2008-3.5-1 | Award Amount: 5.64M | Year: 2009

The objective of EuroPIC is no less than to effect a fundamental change in the way applications based on photonic integrated circuits (PICs) are designed and manufactured in Europe. The key development is to facilitate access by small companies (SMEs) to development and manufacturing of photonic micro-systems in the form of advanced but very cost effective PICs. EuroPIC can bring forth a new production paradigm to forge a sustainable business sector with the potential for very significant future growth. This will be done by developing a generic technology that is capable of realising complex PICs from a small set of basic building blocks. The programme adopts a holistic approach addressing the whole production chain from idea, via proof of concept, design and prototype to product and application. The consortium will carry out research into manufacturing methods and high-throughput processes which will lead to an open-access industrial generic foundry production capability for Europe. It will demonstrate the potential of the generic approach by fabricating a number of Application Specific PICs (ASPICs) with a record combination of complexity and performance, for a wide range of applications in telecommunications, sensors, data communications, medical systems, metrology and consumer photonics. The consortium is in an excellent position to carry out this ambitious task. It includes Europes key players, a mix of SMEs, industry and academic partners, in the fields of component manufacturing, PIC design and applications, photonic CAD, and packaging. Further, EuroPIC is building a strong User Group, many of them SMEs, with committed users from different application fields, which will be actively involved in introducing cost-effective ASPICs in a variety of novel applications, providing Europe with a competitive advantage over the US and the Far East.


Ferreira Da Silva A.,University of Minho | Goncalves A.F.,TMG Automotive | Goncalves A.F.,Lycee Technique du Center | De Almeida Ferreira L.A.,FiberSensing | And 5 more authors.
IEEE Transactions on Industrial Electronics | Year: 2011

Electronic products, including sensors, are often used in harsh environments. However, many parameters, such as severe weather conditions, high electronic noise, or dangerous chemical compounds in situ, may compromise the required high reliability. Therefore, development of a reliable sensing solution for monitoring those extreme conditions may become a very challenging task. This paper presents a smart skin foil developed to meet this specific need. Fiber Bragg grating sensors, one of the most reliable sensor solutions nowadays, were embedded in a thin foil made of polyvinyl chloride, giving rise to a smart structure with high durability and high resistance, and a dimensional stability above 99%. In addition, the fabrication processes used are based on a technology that allows the development of large sensing areas. The sensing foil shows a linear stretching profile, with a slope of 7.8 nm per 1% elongation. After submitting the developed structure to temperature cycles, it revealed a thermal behavior of 0.1 nm ° C. Since the smart sensing structure was fabricated using available industrial fabrication processes, it is a feasible and ready-to-market solution. © 2006 IEEE.


Grant
Agency: European Commission | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2009-1-GRA-01-003 | Award Amount: 239.85K | Year: 2010

FBG sensors have gained increasing importance for structural health monitoring in aeronautics, enabling large-scale measurement of most relevant structural parameters while mitigating technical constrains of conventional sensors. FBG technology application for real-time structural monitoring during flight is currently limited by the lack of flight qualified interrogation equipment. A first goal of the present proposal is the update of currently existing instrumentation to suit the environmental and operational requiems of in-flight applications, increasing instrumentation reliability, and measurement repeatability and precision. An additional issue that should be solved if this technology is to be employed for in-flight monitoring applications is the issue of equipment interfacing with the on board avionics. A second objective of the work will be the analysis of the possible integration of avionic standards within the FBG interrogation equipment, which will allow for direct interfacing with the on board avionics. Finally, the suitability of quasi-distributed FBG sensor arrays for whole area damage detection will be assessed by the implementation and testing of a demonstrator with more than 100 sensors on an composite structure. Results will be compared with other measuring techniques as thermography and ultrasounds. These objectives will be addressed by relying on the teams strong heritage on Fiber Optic Sensing Technology and on aeronautic applications and testing. FiberSensings commercial product portfolio of FBG sensors and interrogation units will be the starting point towards in-flight qualification of equipment and to specific FBG array sensor design for composite embedment. INEGI and NDTEs long experience in testing will provide the necessary knowledge in terms of the test design and completion and on the specific requirements associated to in-flight operation.


Grant
Agency: European Commission | Branch: FP7 | Program: BSG-SME | Phase: SME-2013-1 | Award Amount: 1.35M | Year: 2014

The Tidal Energy Converter Cost Reduction via Power Take Off Optimisation (TIDAL-EC) project proposes a set of research and development activities to substantially improve the economic competitiveness of a key developing sector of the renewable energy market: that of tidal stream power generation. Two of the largest and most critical components of any mainstream tidal energy converter (TEC) are the power take off (PTO) system (the shaft, bearings and other equipment which connects the turbine blades with the generator) and the electrical generator itself. Experts in the field of turbine and generator testing, the UKs National Renewable Energy Centre (NAREC) together with SME partners Tocardo International (TOCARDO),Ocean Flow Energy (OCEANFLOW), Minesto (MINESTO) & FiberSensing (FIBERSENSING) and Research (RTD) performing partners the University of Edinburgh (UEDIN) and SINTEF (SINTEF), plan to conduct vital research and concept design activities to determine the optimum design of a TEC power take off system and permanent magnet generator (PMG). These radically optimised systems will improve reliability, increase power conversion efficiency and facilitate reduction in the cost of tidal power. In turn, the results of this project will also help SME tidal developers (and their SME suppliers) to be able to offer warranties and guarantees to end customers (European Energy Utilities) and enable large scale roll out of tidal energy in the EU; supporting diversification of the European energy mix and helping to achieve European 2020 renewable energy and carbon emission reduction targets. The formation of the consortium has been carefully considered, in parallel with the resource commitments required to support the proposed programme of work. All consortium members have clearly defined roles and responsibilities within the work programme, and have determined that their return on investment is significant, appropriate and is in alignment with their strategic vision.


Tafulo P.A.R.,INESC Porto | Jorge P.A.S.,INESC Porto | Santos J.L.,INESC Porto | Santos J.L.,University of Porto | And 3 more authors.
IEEE Sensors Journal | Year: 2012

Two Fabry-Pérot interferometers based on chemical etching in multimode graded index fibers are fabricated and their response to temperature and strain are compared. Chemical etching is applied in the graded index fiber end creating an air cavity. The interferometric cavity is formed when the graded index fiber with the air concavity is spliced to a single-mode fiber. The intrinsic sensors present high sensitivity to strain and low sensitivity to temperature. For the 62.5 μm core fiber, sensitivities of 6.99 pm/με and, 0.95 pm/°C were obtained for strain and temperature, respectively. The sensor based in the 50 μm core fiber, on the other hand, presented sensitivities of 4.06 pm/με and -0.84 pm/°C for strain and temperature, respectively. © 2006 IEEE.


Viegas D.,INESC Porto | Viegas D.,University of Porto | Hernaez M.,Public University of Navarra | Goicoechea J.,Public University of Navarra | And 5 more authors.
IEEE Sensors Journal | Year: 2011

A novel configuration able to measure simultaneously relative humidity and temperature is proposed. The sensing head is based on a long-period fiber grating (LPG) coated with silica nanospheres in-line with a fiber Bragg grating. The polymeric overlay that changes its optical properties when exposed to different humidity levels is deposited onto the LPG using the electrostatic self-assembly technique (ESA), resulting into a humidity-induced shift of the resonance wavelength of the LPG. Considering the humidity range from 20% to 50% RH, a system resolution of 1.6% RH and 2.5 °C was achieved. At higher humidity, from 50% to 80% RH, the corresponding resolution values were 2.4% RH and 0.4 °C. © 2010 IEEE.


Grant
Agency: European Commission | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2009-1-GRA-01-011 | Award Amount: 78.00K | Year: 2010

Fiber Bragg grating sensors (FBG) for structural health monitoring has gained increasing importance in aerospace applications, since it enables large-scale measurement of most relevant structural parameters while mitigating well-know technical constrains of conventional sensors. The main drawback of a fiber Bragg grating strain sensor is its thermal cross-sensitivity. Currently such a single parameter measurement is difficult to implement, since cross-sensitivity to temperature compels the use of an additional temperature reference. In this project a passive athermal FBG strain gage that renders optional the measurement of temperature is proposed. Such a design will benefit large scale system design and performance. The innovative design will ensure athermal operation of the strain gage by canceling the intrinsic fiber optic thermal sensitivity. Moreover the passive athermal design may be adjusted to further compensate for structural thermal expansion, thus enabling stress and load-induced strain-components to be measured. Special care will be taken on the design of the sensor enclosure to enable multiplexing of several sensors over a single optical fiber and ease installation procedures in aerospace applications. Qualified space fiber optic cables for sensing network deployment will be employed. Commercially available industrial interrogation unit equipment will be taken as a base to evaluate the optoelectronic hardware adaptation that would be required in order to fulfill aerospace specifications. The design requirements will be assessed in terms of mechanical (mass, volume, vibration and shock), thermal (heat dissipation and operation temperature range) and electrical parameters (power consumption and communication interface). Embedded software will allow for data conversion from wavelength measurements to engineering parameters (strain, temperature, load) that will afterwards be processed considering SHM requirements to provide automatic alarm generation.


Grant
Agency: European Commission | Branch: FP7 | Program: JTI-CS | Phase: JTI-CS-2009-1-GRA-01-012 | Award Amount: 80.00K | Year: 2010

The objective of this activity is to design and manufacture composite specimens integrating fibre optic sensors, evaluate the reliability of the sensors, develop a concept to evaluate the system reliability and define a design of experiments of sensorized structures. The purpose of this study is to facilitate the validation of real-time health monitoring systems, which can detect strain as well as the temperature of the structure at multiple locations through numerous embedded optical fibre sensors. Optical fibre sensors for damage detection will be embedded in the structure made of carbon fibre reinforced plastic (CFRP) composite laminates. An integrated assessment of all critical manufacturing steps of fibre Bragg grating strain sensors will be performed in order to achieve high reliability of the embedding process in composite materials. The study will comprise the analysis of different types of optical fibres towards the optimization of embedding processes in composite materials. High resolution strain mapping by embedding series of closely spaced independent sensors in composite material samples will be assessed. Parameters that influence the infant failure of the structures will be analysed and the tests required to asses their effect will be defined. A preliminary test campaign based on thermal, mechanical and fatigue tests have already been defined.

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