412 research outputs found

    Fiber Bragg Gratings for Medical Applications and Future Challenges: A Review

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    [EN] In the last decades, fiber Bragg gratings (FBGs) have become increasingly attractive to medical applications due to their unique properties such as small size, biocompatibility, immunity to electromagnetic interferences, high sensitivity and multiplexing capability. FBGs have been employed in the development of surgical tools, assistive devices, wearables, and biosensors, showing great potentialities for medical uses. This paper reviews the FBG-based measuring systems, their principle of work, and their applications in medicine and healthcare. Particular attention is given to sensing solutions for biomechanics, minimally invasive surgery, physiological monitoring, and medical biosensing. Strengths, weaknesses, open challenges, and future trends are also discussed to highlight how FBGs can meet the demands of next-generation medical devices and healthcare system.This work was supported in part by INAIL (the Italian National Institute for Insurance against Accident at Work), through the BRIC (Bando ricerche in collaborazione) 2018 SENSE-RISC (Sviluppo di abiti intelligENti Sensorizzati per prevenzione e mitigazione di Rischi per la SiCurezza dei lavoratori) Project under Grant ID10/2018, in part by the UCBM (Universita Campus Bio-Medico di Roma) under the University Strategic HOPE (HOspital to the PatiEnt) Project, in part by the EU Framework Program H2020-FETPROACT-2018-01 NeuHeart Project under Grant GA 824071, by FCT/MEC (Fundacao para a Ciencia e Tecnologia) under the Projects UIDB/50008/2020 - UIDP/50008/2020, and by REACT (Development of optical fiber solutions for Rehabilitation and e-Health applications) FCT-IT-LA scientific action.Lo Presti, D.; Massaroni, C.; Leitao, CSJ.; Domingues, MDF.; Sypabekova, M.; Barrera, D.; Floris, I.... (2020). Fiber Bragg Gratings for Medical Applications and Future Challenges: A Review. IEEE Access. 8:156863-156888. https://doi.org/10.1109/ACCESS.2020.3019138S156863156888

    Optimization of multicore optical fibers with fiber Bragg gratings towards bend and shape sensing

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    A shape sensor based on fiber Bragg gratings (FBGs) in multicore fibers is a complex device with multiple factors which have to be accounted for a successful measure- ment system. In this dissertation, I considered several aspects of such shape and curvature sensors

    Pose Measurement of Flexible Medical Instruments Using Fiber Bragg Gratings in Multi-Core Fiber

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    Accurate navigation of flexible medical instruments like catheters require the knowledge of its pose, that is its position and orientation. In this paper multi-core fibers inscribed with fiber Bragg gratings (FBG) are utilized as sensors to measure the pose of a multi-segment catheter. A reconstruction technique that provides the pose of such a fiber is presented. First, the measurement from the Bragg gratings are converted to strain then the curvature is deduced based on those strain calculations. Next, the curvature and the Bishop frame equations are used to reconstruct the fiber. This technique is validated through experiments where the mean error in position and orientation is observed to be less than 4.69 mm and 6.48 degrees, respectively. The main contributions of the paper are the use of Bishop frames in the reconstruction and the experimental validation of the acquired pose

    Distributed, Advanced Fiber Optic Sensors

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    India is poised to use nuclear energy in a big way. The safety of these systems depends upon monitoring various parameters in hazardous environment like high radiation, high temperature exceeding 1000°C, and gas/coolant leakages. In this chapter, we shall dwell on basics of distributed sensing, related instrumentation, device fabrication, and actual advanced field applications. Techniques like Raman scattering, resonance response of fiber gratings, and selective absorption are employed for design, development, and fabrication of distributed sensors and devices. Raman distributed sensors with advanced data processing techniques are finding increasing applications for fire detection, coolant leak detection, and safety of large structures. The systematic investigations related to portable systems developed at the author’s lab have been described. Wavelength-encoded fiber gratings are the attractive candidate for high gamma radiation dose measurements in environment such as particle accelerators, fission reactors, food processing facilities, and ITER-like installations. The basics of fiber gratings, their operational designs, and devices based on fiber gratings have been described with advanced applications like high temperature sensing, strain measurements at cryogenic temperatures, and strain in nuclear environment. Finally, novel approaches are described for distributed hazardous gas monitoring for large areas such as airports, train stations, and reactor containment buildings

    Dual-Parameter Opto-Mechanical Fiber Optic Sensors for Harsh Environment Sensing: Design, Packaging, Calibration, and Applications

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    This thesis concerns with the development of a dual-parameter sensor based on fiber Bragg grating (FBG) and a packaging design for high pressure sensing in harsh environment. This thesis starts by introducing a novel design of a partially coated FBG, using a metallic insert and a thermal curing epoxy. An analytical opto-mechanical model, based on couple mode theory, was developed and presented. The experimental and modelling result of the optical response of the partially coated FBG were compared and shown to be in excellent agreement. The experiments were executed on a custom-built fiber optic calibration station. The coated FBG sensor has a temperature sensitivity of 26.9 ± 0.3 pm/°C, which is 2.7 times higher than a bare fiber; and a force sensitivity of 0.104 nm/N, which is 13 times smaller than a bare fiber. The zero reference of the sensor has a drift of a maximum of 70 pm but the sensor is shown to settle within ±5 pm after 3 thermal cycles and 10 tensile loading cycles. A low profile packaging design is presented for a maximum pressure of 20.68 MPa (3000 psi) for harsh environment applications. A detailed study with FEM analysis revealed the optimal design for the package’s sleeve thickness is 0.5 mm. The temperature sensitivity is in close agreement with the unpackaged coated sensor with 10% difference. Compared to the modelling, the equivalent force sensitivity is 27% lower due to prototype dimensional uncertainties and modelling uncertainties with the material properties. The lack of pre-tension of the FBG sensor in the package also attributed to lower force sensitivity at pressure level lower than 4.13 MPa (600 psi).1 yea

    Sensores em fibra ótica para o estudo biomecânico do disco intervertebral

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    Doutoramento em Engenharia MecânicaO presente trabalho teve como objetivo principal estudar o comportamento mecânico do disco intervertebral recorrendo a sensores em fibra ótica. Na expetativa de efetuar o melhor enquadramento do tema foi efetuada uma revisão exaustiva das várias configurações de sensores em fibra ótica que têm vindo a ser utilizadas em aplicações biomédicas e biomecânicas, nomeadamente para medição de temperatura, deformação, força e pressão. Nesse âmbito, procurou-se destacar as potencialidades dos sensores em fibra ótica e apresentá-los como uma tecnologia alternativa ou até de substituição das tecnologias associadas a sensores convencionais. Tendo em vista a aplicação de sensores em fibra ótica no estudo do comportamento do disco intervertebral efetuou-se também uma revisão exaustiva da coluna vertebral e, particularmente, do conceito de unidade funcional. A par de uma descrição anatómica e funcional centrada no disco intervertebral, vértebras adjacentes e ligamentos espinais foram ainda destacadas as suas propriedades mecânicas e descritos os procedimentos mais usuais no estudo dessas propriedades. A componente experimental do presente trabalho descreve um conjunto de experiências efetuadas com unidades funcionais cadavéricas utilizando sensores convencionais e sensores em fibra ótica com vista à medição da deformação do disco intervertebral sob cargas compressivas uniaxiais. Inclui ainda a medição in vivo da pressão intradiscal num disco lombar de uma ovelha sob efeito de anestesia. Para esse efeito utilizou-se um sensor comercial em fibra ótica e desenvolveu-se a respetiva unidade de interrogação. Finalmente apresenta-se os resultados da investigação em curso que tem como objetivo propor e desenvolver protótipos de sensores em fibra ótica para aplicações biomédicas e biomecânicas. Nesse sentido, são apresentadas duas soluções de sensores interferométricos para medição da pressão em fluídos corporais.The present work aimed to study the mechanical behavior of the intervertebral disc using fiber optic sensors. To address the theme an exhaustive review of the various configurations of fiber optic sensors that have been used in biomechanical and biomedical applications, in particular for measuring temperature, strain, force and pressure, was conducted. In this context, an effort was made to highlight the advantages of fiber optic sensors and present them as an alternative or even a substitution technology to conventional sensors. In view of the application of fiber optic sensors to study intervertebral disc behavior an exhaustive review of the spine and, particularly, of the spinal motion segment was made. Along with an anatomical and functional description of the intervertebral disc, the adjacent vertebrae and spinal ligaments, their mechanical properties were also highlighted as well as the most common procedures and guidelines followed in the study of these properties. The experimental section of the present work describes a set of tests performed with cadaveric spinal motion segments using conventional and fiber optic sensors to assess strain of the intervertebral disc under uniaxial compressive loads. This section also includes an experience reporting in vivo pressures measured in the lumbar disc of a sheep under general anesthesia. In this case, a commercial fiber optic sensor and a purpose-built interrogation unit were used. Finally, the results of ongoing research aiming to develop fiber optic sensors prototypes for biomedical and biomechanical applications are presented. Thus, the proof of concept of two possible interferometric configurations intended for pressure measurement in body fluids was presented
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