Journal articles: 'Biomedical applications of FBGs'

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Shekhar, Himanshu, Kuldeep Jajoria, Chandan K. Jha, and Arup L. Chakraborty. "Fiber Bragg grating technology for biomedical ultrasound applications." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A226. http://dx.doi.org/10.1121/10.0016090.

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Fiber Bragg gratings (FBGs) are a class of optical sensors that have been used widely in non destructive testing and monitoring. These sensors are compact, robust, inexpensive and immune to electromagnetic interference. FBGs serve as wavelength selective mirrors that reflect light at the Bragg wavelength. An applied strain results in a shift in the Bragg wavelength, which can be used to detect physical parameters such as temperature and pressure. Recent work suggests that FBGs could have potential for measurements in the biomedical ultrasound frequency range. In this presentation, I will provide an overview of ongoing work in our group on employing FBGs for applications in therapeutic ultrasound. Specifically, I will discuss calibration of these sensors along with their use in passive cavitation detection. I will also present recent results on detecting nonlinear waveforms relevant to focused ultrasound along with temperature measurement for thermal therapy. We envisage that these sensors will be useful in laboratory research environments, and for specialized therapy applications in the clinical setting.

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Zhang, Wen, Lianqing Zhu, Mingli Dong, Xiaoping Lou, and Feng Liu. "A Temperature Fiber Sensor Based on Tapered Fiber Bragg Grating Fabricated by Femtosecond Laser." Applied Sciences 8, no. 12 (December 14, 2018): 2616. http://dx.doi.org/10.3390/app8122616.

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A temperature fiber sensor based on tapered fiber Bragg grating (tapered FBG) fabricated by femtosecond laser has been proposed and realized with good reproducibility. Firstly, the fiber taper with 25 μm diameter and 1000 μm length is fabricated by arc-discharge elongation using two standard single-mode fibers. Secondly, two first-order FBGs are fabricated in tapered and non-tapered fiber regions for comparison. Both FBGs are point-by-point direct-written by femtosecond laser, and the grating lengths are 1000 μm. Thirdly, a temperature experiment is performed using a heating chamber, and experimental results show that in the range of 30~350 °C, the temperature sensitivity of the tapered FBG has increased from 11.0 pm/°C to 12.3 pm/°C. The tapered FBG proposed here can be further configured for sensing other parameters in physical, chemical, and biomedical applications.

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De Tommasi, Francesca, Chiara Romano, Daniela Lo Presti, Carlo Massaroni, Massimiliano Carassiti, and Emiliano Schena. "FBG-Based Soft System for Assisted Epidural Anesthesia: Design Optimization and Clinical Assessment." Biosensors 12, no. 8 (August 16, 2022): 645. http://dx.doi.org/10.3390/bios12080645.

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Fiber Bragg grating sensors (FBGs) are considered a valid sensing solution for a variety of medical applications. The last decade witnessed the exploitation of these sensors in applications ranging from minimally invasive surgery to biomechanics and monitoring physiological parameters. Recently, preliminary studies investigated the potential impact of FBGs in the management of epidural procedures by detecting when the needle reaches the epidural space with the loss of resistance (LOR) technique. In this article, we propose a soft and flexible FBG-based system capable of detecting the LOR, we optimized the solution by considering different designs and materials, and we assessed the feasibility of the optimized soft sensor (SS) in clinical settings. The proposed SS addresses some of the open challenges in the use of a sensing solution during epidural punctures: it has high sensitivity, it is non-invasive, the sensing element does not need to be inserted within the needle, and the clinician can follow the standard clinical practice. Our analysis highlights how the material and the design impact the system response, and thus its performance in this scenario. We also demonstrated the system’s feasibility of detecting the LOR during epidural procedures.

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KOT, Marcin, Łukasz MAJOR, Roman MAJOR, Jurgen LACKNER, and Maureen PONTIE. "COATINGS WITH ADVANCED MICROSTRUCTURE FOR BIOMEDICAL APPLICATIONS." Tribologia 272, no. 2 (April 30, 2017): 77–83. http://dx.doi.org/10.5604/01.3001.0010.6301.

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The paper presents the effect of the complex architecture of Cr/CrN+a-C:H coatings on their mechanical and tribological properties. These advanced coatings were compared with CrN single coatings and Cr/CrN multilayers. All of them were deposited by the magnetron sputtering technique. The conducted tests allowed nanohardness, elasticity modulus, fracture toughness, and adhesion of coatings to steel substrates to be determined. Tribological tests were carried out under dry friction and in the presence of phosphate-buffered saline PBS and foetal bovine serum FBS. For all test conditions, the friction coefficient and the wear index of the produced coatings were determined. The lowest wear and the lowest coefficient of friction are exhibited by coatings with complex Cr/CrN+a-C:H architecture. Furthermore, they are also resistant to the highly corrosive PBS environment.

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Chaitin, Hersh, Michael L. Lu, Michael B. Wallace, and Yunqing Kang. "Development of a Decellularized Porcine Esophageal Matrix for Potential Applications in Cancer Modeling." Cells 10, no. 5 (April 29, 2021): 1055. http://dx.doi.org/10.3390/cells10051055.

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Many decellularized extracellular matrix-derived whole organs have been widely used in studies of tissue engineering and cancer models. However, decellularizing porcine esophagus to obtain decellularized esophageal matrix (DEM) for potential biomedical applications has not been widely investigated. In this study a modified decellularization protocol was employed to prepare a porcine esophageal DEM for the study of cancer cell growth. The cellular removal and retention of matrix components in the porcine DEM were fully characterized. The microstructure of the DEM was observed using scanning electronic microscopy. Human esophageal squamous cell carcinoma (ESCC) and human primary esophageal fibroblast cells (FBCs) were seeded in the DEM to observe their growth. Results show that the decellularization process did not cause significant loss of mechanical properties and that blood ducts and lymphatic vessels in the submucosa layer were also preserved. ESCC and FBCs grew on the DEM well and the matrix did not show any toxicity to cells. When FBS and ESCC were cocultured on the matrix, they secreted more periostin, a protein that supports cell adhesion on matrix. This study shows that the modified decellularization protocol can effectively remove the cell materials and maintain the microstructure of the porcine esophageal matrix, which has the potential application of studying cell growth and migration for esophageal cancer models.

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Binetti, Leonardo, Alicja Stankiewicz, and Lourdes S. M. Alwis. "Graphene-Oxide and Hydrogel Coated FBG-Based pH Sensor for Biomedical Applications." Proceedings 2, no. 13 (December 3, 2018): 789. http://dx.doi.org/10.3390/proceedings2130789.

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A hydrogel coated fibre grating-based pH sensor for biomedical applications has been realised, where Graphene Oxide (GO) had been used to enhance the bonding between the coating and the fibre. Two methods of deposition of GO were analysed i.e., evaporation and co-electroplating. The paper concludes that the system of GO evaporated on the fibre + the hydrogel has a sensitivity much higher, (6.1 ± 0.5) pm/pH, than the system of Cu and GO co-electroplated + the hydrogel, (1.9 ± 0.1) pm/pH, for a pH range between 2 to 10. The other conclusion is that the first system has a less coating bonding energy with the optical fibre whereas the second system has a stronger bonding energy, with better durability.

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Kanellos, George T., George Papaioannou, Dimitris Tsiokos, Christos Mitrogiannis, George Nianios, and Nikos Pleros. "Two dimensional polymer-embedded quasi-distributed FBG pressure sensor for biomedical applications." Optics Express 18, no. 1 (December 22, 2009): 179. http://dx.doi.org/10.1364/oe.18.000179.

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Safoine, Meryem, Alexandra Côté, Romane Leloup, Cindy Jean Hayward, Marc-André Plourde Campagna, Jean Ruel, and Julie Fradette. "Engineering naturally-derived human connective tissues for clinical applications using a serum-free production system." Biomedical Materials 17, no. 5 (August 11, 2022): 055011. http://dx.doi.org/10.1088/1748-605x/ac84b9.

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Abstract The increasing need for tissue substitutes in reconstructive surgery spurs the development of engineering methods suited for clinical applications. Cell culture and tissue production traditionally require the use of fetal bovine serum (FBS) which is associated with various complications especially from a translational perspective. Using the self-assembly approach of tissue engineering, we hypothesized that all important parameters of tissue reconstruction can be maintained in a production system devoid of FBS from cell extraction to tissue reconstruction. We studied two commercially available serum-free medium (SFM) and xenogen-free serum-free medium (XSFM) for their impact on tissue reconstruction using human adipose-derived stem/stromal cells (ASCs) in comparison to serum-containing medium. Both media allowed higher ASC proliferation rates in primary cultures over five passages compared with 10% FBS supplemented medium while maintaining high expression of mesenchymal cell markers. For both media, we evaluated extracellular matrix production and deposition necessary to engineer manipulatable tissues using the self-assembly approach. Tissues produced in SFM exhibited a significantly increased thickness (up to 6.8-fold) compared with XSFM and FBS-containing medium. A detailed characterization of tissues produced under SFM conditions showed a substantial 50% reduction of production time without compromising key tissue features such as thickness, mechanical resistance and pro-angiogenic secretory capacities (plasminogen activator inhibitor 1, hepatocyte growth factor, vascular endothelial growth factor, angiopoietin-1) when compared to tissues produced in the control FBS-containing medium. Furthermore, we compared ASCs to the frequently used human dermal fibroblasts (DFs) in the SFM culture system. ASC-derived tissues displayed a 2.4-fold increased thickness compared to their DFs counterparts. In summary, we developed all-natural human substitutes using a production system compatible with clinical requirements. Under culture conditions devoid of bovine serum, the resulting engineered tissues displayed similar and even superior structural and functional properties over the classic FBS-containing culture conditions with a considerable 50% shortening of production time.

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Masud, Usman, Muhammad Rizwan Amirzada, Hassan Elahi, Faraz Akram, Ahmed Zeeshan, Yousuf Khan, Muhammad Khurram Ehsan, et al. "Design of Two-Mode Spectroscopic Sensor for Biomedical Applications: Analysis and Measurement of Relative Intensity Noise through Control Mechanism." Applied Sciences 12, no. 4 (February 11, 2022): 1856. http://dx.doi.org/10.3390/app12041856.

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The design of an intracavity spectroscopy based two-mode biomedical sensor involves a thorough investigation of the system. For this purpose, the individual components that are present in the system must be examined. This work describes the principle of two very important gadgets, namely the Fibre Bragg Grating (FBG), and the tunable coupler. We adhere to a Petri network scheme to model and analyze the performance of the FBG, and the results mirror strikingly low difference in the values of Bragg Wavelength during its ascending and descending operational principle, thereby maintaining the accuracy of the sensor’s results. Next, a pseudocode is developed and implemented for the investigation of the optical coupler in LabView. The values of its maximum output power are determined, and the coupling ratio for various values of controlling voltage is determined at three different wavelengths. The hysteresis results mirror an extremely low difference between the forward and reverse values in the results. Both the results of the FBG and the coupler are thereby extremely reliable to use them in the laser system, as evident from the respective intensity noise outcomes, as well as the experimentation on substances of interest (Dichloro Methane and Propofol).

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He, Yanlin, Xu Zhang, Lianqing Zhu, Guangkai Sun, Xiaoping Lou, and Mingli Dong. "Optical Fiber Sensor Performance Evaluation in Soft Polyimide Film with Different Thickness Ratios." Sensors 19, no. 4 (February 15, 2019): 790. http://dx.doi.org/10.3390/s19040790.

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To meet the application requirements of curvature measurement for soft biomedical robotics and flexible morphing wings of aircraft, the optical fiber Bragg grating (FBG) shape sensor for soft robots and flexible morphing wing was implemented. This optical FBG is embedded in polyimide film and then fixed in the body of a soft robot and morphing wing. However, a lack of analysis on the embedded depth of FBG sensors in polyimide film and its sensitivity greatly limits their application potential. Herein, the relationship between the embedded depth of the FBG sensor in polyimide film and its sensitivity and stability are investigated. The sensing principle and structural design of the FBG sensor embedded in polyimide film are introduced; the bending curvatures of the FBG sensor and its wavelength shift in polyimide film are studied; and the relationship between the sensitivity, stability, and embedded depth of these sensors are verified experimentally. The results showed that wavelength shift and curvature have a linear relationship. With the sensor’s curvature ranging from 0 m−1 to 30 m−1, their maximum sensitivity is 50.65 pm/m−1, and their minimum sensitivity is 1.96 pm/m−1. The designed FBG sensor embedded in polyimide films shows good consistency in repeated experiments for soft actuator and morphing wing measurement; the FBG sensing method therefore has potential for real applications in shape monitoring in the fields of soft robotics and the flexible morphing wings of aircraft.

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Najafzadeh, Ali, Dinusha Serandi Gunawardena, Zhengyong Liu, Ton Tran, Hwa-Yaw Tam, Jing Fu, and Bernard K. Chen. "Application of Fibre Bragg Grating Sensors in Strain Monitoring and Fracture Recovery of Human Femur Bone." Bioengineering 7, no. 3 (August 19, 2020): 98. http://dx.doi.org/10.3390/bioengineering7030098.

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Fibre Bragg Grating (FBG) sensors are gaining popularity in biomedical engineering. However, specific standards for in vivo testing for their use are absolutely limited. In this study, in vitro experimental tests were performed to investigate the behaviors and applications of gratings attached to intact and fractured thighbone for a range of compression loading (<300 N) based around some usual daily activities. The wavelength shifts and the corresponding strain sensitivities of the FBG sensors were measured to determine their effectiveness in monitoring the femoral fracture healing process. Four different arrangements of FBG sensors were selected to measure strains at different critical locations on the femoral sawbones surface. Data obtained for intact and plated sawbones were compared using both embedded longitudinal and coiled FBG arrays. Strains were measured close to the fracture, posterior linea aspera and popliteal surface areas, as well as at the proximal and distal ends of the synthetic femur; their responses are discussed herein. The gratings on the longitudinally secured FBG arrays were found to provide high levels of sensitivity and precise measurements, even for relatively small loads (<100 N). Nevertheless, embedding angled FBG sensors is essential to measure the strain generated by applied torque on the femur bone. The maximum recorded strain of the plated femur was 503.97 µε for longitudinal and −274.97 µε for coiled FBG arrays, respectively. These project results are important to configure effective arrangements and orientations of FBG sensors with respect to fracture position and fixation implant for future in vivo experiments.

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He, Jun, Baijie Xu, Xizhen Xu, Changrui Liao, and Yiping Wang. "Review of Femtosecond-Laser-Inscribed Fiber Bragg Gratings: Fabrication Technologies and Sensing Applications." Photonic Sensors 11, no. 2 (April 1, 2021): 203–26. http://dx.doi.org/10.1007/s13320-021-0629-2.

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AbstractFiber Bragg grating (FBG) is the most widely used optical fiber sensor due to its compact size, high sensitivity, and easiness for multiplexing. Conventional FBGs fabricated by using an ultraviolet (UV) laser phase-mask method require the sensitization of the optical fiber and could not be used at high temperatures. Recently, the fabrication of FBGs by using a femtosecond laser has attracted extensive interests due to its excellent flexibility in creating FBGs array or special FBGs with complex spectra. The femtosecond laser could also be used for inscribing various FBGs on almost all fiber types, even fibers without any photosensitivity. Such femtosecond-laser-induced FBGs exhibit excellent thermal stability, which is suitable for sensing in harsh environment. In this review, we present the historical developments and recent advances in the fabrication technologies and sensing applications of femtosecond-laser-inscribed FBGs. Firstly, the mechanism of femtosecond-laser-induced material modification is introduced. And then, three different fabrication technologies, i.e., femtosecond laser phase mask technology, femtosecond laser holographic interferometry, and femtosecond laser direct writing technology, are discussed. Finally, the advances in high-temperature sensing applications and vector bending sensing applications of various femtosecond-laser-inscribed FBGs are summarized. Such femtosecond-laser-inscribed FBGs are promising in many industrial areas, such as aerospace vehicles, nuclear plants, oil and gas explorations, and advanced robotics in harsh environments.

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Grande Tovar, Carlos, Jorge Castro, Carlos Valencia, Diana Navia Porras, José Mina Hernandez, Mayra Valencia, José Velásquez, and Manuel Chaur. "Preparation of Chitosan/Poly(Vinyl Alcohol) Nanocomposite Films Incorporated with Oxidized Carbon Nano-Onions (Multi-Layer Fullerenes) for Tissue-Engineering Applications." Biomolecules 9, no. 11 (November 1, 2019): 684. http://dx.doi.org/10.3390/biom9110684.

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Recently, tissue engineering became a very important medical alternative in patients who need to regenerate damaged or lost tissues through the use of scaffolds that support cell adhesion and proliferation. Carbon nanomaterials (carbon nanotubes, fullerenes, multi-wall fullerenes, and graphene) became a very important alternative to reinforce the mechanical, thermal, and antimicrobial properties of several biopolymers. In this work, five different formulations of chitosan/poly(vinyl alcohol)/oxidized carbon nano-onions (CS/PVA/ox-CNO) were used to prepare biodegradable scaffolds with potential biomedical applications. Film characterization consisted of Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tension strength, Young’s modulus, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The degradation in a simulated body fluid (FBS) demonstrated that all the formulations lost between 75% and 80% of their weight after 15 days of treatment, but the degradation decreased with the ox-CNO content. In vivo tests after 90 days of subdermal implantation of the nanocomposite films in Wistar rats’ tissue demonstrated good biocompatibility without allergenic reactions or pus formation. There was a good correlation between FBS hydrolytic degradation and degradation in vivo for all the samples, since the ox-CNO content increased the stability of the material. All these results indicate the potential of the CS/PVA/ox-CNO nanocomposite films in tissue engineering, especially for long-term applications.

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Teterina, Anastasia Yu, Vladislav V. Minaychev, Polina V. Smirnova, Margarita I. Kobiakova, Igor V. Smirnov, Roman S. Fadeev, Alexey A. Egorov, et al. "Injectable Hydrated Calcium Phosphate Bone-like Paste: Synthesis, In Vitro, and In Vivo Biocompatibility Assessment." Technologies 11, no. 3 (June 15, 2023): 77. http://dx.doi.org/10.3390/technologies11030077.

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The injectable hydrated calcium phosphate bone-like paste (hCPP) was developed with suitable rheological characteristics, enabling unhindered injection through standard 23G needles. In vitro assays showed the cytocompatibility of hCPP with mesenchymal embryonic C3H10T1/2 cell cultures. The hCPP was composed of aggregated micro-sized particles with sphere-like shapes and low crystallinity. The ability of hCPP particles to adsorb serum proteins (FBS) was investigated. The hCPP demonstrated high protein adsorption capacity, indicating its potential in various biomedical applications. The results of the in vivo assay upon subcutaneous injection in Wistar rats indicated nontoxicity and biocompatibility of experimental hCPP, as well as gradual resorption of hCPP, comparable to the period of bone regeneration. The data obtained are of great interest for the development of commercial highly effective osteoplastic materials for bone tissue regeneration and augmentation.

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Ferdinand, Pierre, Sylvain Magne, Véronique Dewynter-Marty, Stéphane Rougeault, and Laurent Maurin. "Applications of Fiber Bragg Grating Sensors in the Composite Industry." MRS Bulletin 27, no. 5 (May 2002): 400–407. http://dx.doi.org/10.1557/mrs2002.126.

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AbstractOptical-fiber sensors based on fiber Bragg gratings (FBGs) provide accurate, nonintrusive, and reliable remote measurements of temperature, strain, and pressure, and they are immune to electromagnetic interference. FBGs are extensively used in telecommunications, and their manufacture is now cost-effective. As sensors, FBGs find many industrial applications in composite structures used in the civil engineering, aeronautics, train transportation, space, and naval sectors. Tiny FBG sensors embedded in a composite material can provide in situ information about polymer curing (strain, temperature, refractive index) in an elegant and nonintrusive way. Great improvements in composite manufacturing processes such as resin transfer molding (RTM) and resin film infusion (RFI) have been obtained through the use of these sensors. They can also be used in monitoring the “health” of a composite structure and in impact detection to evaluate, for example, the airworthiness of aircraft. Finally, FBGs may be used in instrumentation as composite extensometers or strain rosettes, primarily in civil engineering applications.

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Tiwari, BK, and Rajiv Sharma. "A Computing Model for Design of Flexible Buoyancy System for Autonomous Underwater Vehicles and Gliders." Defence Science Journal 68, no. 6 (October 31, 2018): 589. http://dx.doi.org/10.14429/dsj.68.12548.

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Modern design approaches are conceived and utilised in an integrated loop covering system statics, dynamics, optimisation, and others. In this regard this paper presents a computing based integrated design approach for a flexible buoyancy system (FBS) aimed towards the applications in autonomous underwater vehicles and gliders. The primary design alternatives for the FBS are: piston and pump driven and both are investigated. The primary design of autonomous underwater vehicles and gliders is computed from first principle of mechanics and defined in the computer aided design model and it is implemented in the Matlab*TM. Lastly, to show the application of the present approach, a design example is presented for a water depth of 6000 m.

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Lupi, Carla, Ferdinando Felli, Alessandro Dell’Era, Erwin Ciro, Michele Caponero, Hypolito Kalinowski, and Cristian Vendittozzi. "Critical Issues of Double-Metal Layer Coating on FBG for Applications at High Temperatures." Sensors 19, no. 18 (September 4, 2019): 3824. http://dx.doi.org/10.3390/s19183824.

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Use of fiber Bragg gratings (FBGs) to monitor high temperature (HT) applications is of great interest to the research community. Standard commercial FBGs can operate up to 600 ∘ C. For applications beyond that value, specific processing of the FBGs must be adopted to allow the grating not to deteriorate. The most common technique used to process FBGs for HT applications is the regeneration procedure (RP), which typically extends their use up to 1000 ∘ C. RP involves a long-term annealing of the FBGs, to be done at a temperature ranging from 550 to 950 ∘ C. As at that temperature, the original coating of the FBGs would burn out, they shall stay uncoated, and their brittleness is a serious concern to deal with. Depositing a metal coating on the FBGs prior to process them for RP offers an effective solution to provide them with the necessary mechanical strengthening. In this paper, a procedure to provide the FBG with a bimetallic coating made by copper and nickel electrodeposition (ED) is proposed, discussing issues related to the coating morphology, adherence to the fiber, and effects on the grating spectral response. To define the processing parameters of the proposed procedure, production tests were performed on dummy samples which were used for destructive SEM–EDS analysis. As a critical step, the proposed procedure was shown to necessitate a heat treatment after the nickel ED, to remove the absorbed hydrogen. The spectral response of the FBG samples was monitored along the various steps of the proposed procedure and, as a final proof test for adherence stability of the bimetallic coating, along a heating/cooling cycle from room temperature to 1010 ∘ C. The results suggest that, given the emergence of Kirkendall voids at the copper–nickel interface, occurring at the highest temperatures (700–1010 ∘ C), the bimetallic layer could be employed as FBG coating up to 700 ∘ C.

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Lei, Luohao, Hongye Li, Jing Shi, Qihao Hu, Xiaofan Zhao, Baiyi Wu, Meng Wang, and Zefeng Wang. "Miniature Fabry-Perot Cavity Based on Fiber Bragg Gratings Fabricated by Fs Laser Micromachining Technique." Nanomaterials 11, no. 10 (September 26, 2021): 2505. http://dx.doi.org/10.3390/nano11102505.

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Fabry-Perot cavity (FPC) based on Fiber Bragg gratings (FBGs) is an excellent candidate for fiber sensing and high-precision measurement. The advancement of the femtosecond laser micromachining technique provides more choices for the fabrication of FBGs-based FPCs. In this paper, we fabricate miniature FBGs-based FPCs, using the femtosecond laser line-by-line scanning writing technique for the first time. By this method, the FBGs can be limited to a specific area in the fiber core region. The grating length, position, and the distance between two successive FBGs can be conveniently controlled to achieve the desired transmission spectrum. For future applications in sensing, the temperature and strain responses of the fabricated FBGs-based FPCs were studied experimentally. This work provides a meaningful guidance for the fabrication and application of miniature FPCs based on FBGs.

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Wan, Ying, Chen Jiang, Zuxing Zhang, Yaya Mao, Jianxin Ren, Jianxiang Wen, and Yunqi Liu. "All-Fiber Narrow-Bandwidth Mode-Locked Laser Based on Polarization-Dependent Helical Long-Period Grating." Photonics 10, no. 7 (July 21, 2023): 842. http://dx.doi.org/10.3390/photonics10070842.

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As a crucial component of nonlinear polarization rotation (NPR) mode locking, optical fiber gratings offer advantages such as polarization modulation capability, stability, fiber compatibility, and preparation maturity, making them a vital technological foundation for achieving NPR mode locking. Here, a polarization-maintaining fiber helical long-period grating (PMF-HLPG) was designed and fabricated as a polarizer using the CO2-laser direct-write technique to realize the NPR effect. A homemade fiber Bragg grating (FBG) was also introduced into the laser system to enable a narrow-bandwidth lasing output and wavelength tunability. Based on the PMF-HLPG and FBG mentioned above, an all-fiber mode-locked laser with a spectra bandwidth of 0.15 nm was constructed to generate stable short pulses with a fundamental repetition rate of 12.7122 MHz and a pulse duration of 30.08 ps. In particular, its signal-to-noise ratio is up to 84.5 dB, showing the high stability of the laser. Further, the operating wavelength of the laser can be tuned from 1559.65 nm to 1560.29 nm via heating the FBG while maintaining its mode-locked state with stability. The results indicate that the PMF-HLPG could be used as a polarizer to meet the NPR mechanism for ultrashort pulse laser applications in optical communication, optical sensing, and biomedical imaging.

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Salvador, Daniela, Henrique Almeida, Duarte Rego, Pedro Mendonça, Ana Paula Sousa, Margarida Serra, and Luis Redondo. "Pulsed Electric Fields for Valorization of Platelets with No Therapeutic Value towards a High Biomedical Potential Product—A Proof of Concept." Applied Sciences 12, no. 12 (June 7, 2022): 5773. http://dx.doi.org/10.3390/app12125773.

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Nowadays, the standard media used in clinical-scale mesenchymal stem cell (MSC) production to supply hundreds of clinical trials uses animal-derived components as supplements, which raises several health concerns. Consequently, the development of xeno-free media supplements has emerged. In the current study, the effect of pulse electric field (PEF) application to platelet concentrates (PC) with no therapeutic value for producing platelet releasates (PR) able to sustain the ability of bone marrow-MSCs (BM-MSCs) to self-renew and differentiate was tested. It was demonstrated that PEF application to PC induces platelet activation and growth factor (GF) release, namely PDGF, FGF, IGF, and TGF-β. The highest GF release was observed for TGF-β, achieving similar levels to those attained in platelet lysates (PL). BM-MSCs expanded in the presence of PR obtained by the application of PEF (7 pulses of 10 and 12.5 kV/cm) to PC (PR PEF) retained the characteristic MSC cell-surface markers, and the ability to proliferate and differentiate into osteogenic, adipogenic, and chondrogenic lineages. In this study, evidence is provided that PR PEF represents a suitable alternative to fetal bovine serum (FBS) for use in MSC production.

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Fernández-Ruiz, María R., and Alejandro Carballar. "Fiber Bragg Grating-Based Optical Signal Processing: Review and Survey." Applied Sciences 11, no. 17 (September 3, 2021): 8189. http://dx.doi.org/10.3390/app11178189.

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This paper reviews the state of the art of fiber Bragg gratings (FBGs) as analog all-optical signal processing units. Besides the intrinsic advantages of FBGs, such as relatively low cost, low losses, polarization insensitivity and full compatibility with fiber-optic systems, they have proven to deliver an exceptional flexibility to perform any complex band-limited spectral response by means of the variation of their physical parameters. These features have made FBGs an ideal platform for the development of all-optical broadband filters and pulse processors. In this review, we resume the main design algorithms of signal processors based on FBGs, and we revisit the most common processing units based on FBGs and the applications that have been presented in the literature.

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Iadicicco, Agostino, Antonello Cutolo, and Andrea Cusano. "Fiber Bragg Grating Sensors - Advancements and Industrial Applications." Advances in Science and Technology 55 (September 2008): 213–22. http://dx.doi.org/10.4028/www.scientific.net/ast.55.213.

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Over the last few years, optical fiber sensors have seen increased acceptance and widespread use for a variety of applications ranging from structural sensing and health monitoring of composites and structures in civil and aeronautic areas; to pressure and temperature sensors for oil and gas reservoir monitoring to name just a few. Among them Fiber Bragg Grating (FBG) based sensors have become widely known and popular within and out the photonics community and seen a rise in their utilization and commercial growth. Given the capability of FBGs to measure a multitude of parameters such as strain, temperature, pressure, chemical and bio-logical agents and many others coupled with their flexibility of design to be used as single point or multi-point sensing arrays and their relative low cost, make them ideal devices to be adopted for a multitude of different sensing applications and implemented in different fields and industries. This work first focuses on some recent experiences in the use of FBGs for opto-acoustic sensors and railway monitoring and then reviews the advances in the area of FBGs evanescent wave sensors as valuable technological platforms for chemical and biological applications.

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Chen, Ya-Ting, Shu-Ling Hsieh, Wei-Siang Gao, Li-Jung Yin, Cheng-Di Dong, Chiu-Wen Chen, Reeta-Rani Singhania, Shuchen Hsieh, and Shu-Jen Chen. "Evaluation of Chemical Compositions, Antioxidant Capacity and Intracellular Antioxidant Action in Fish Bone Fermented with Monascus purpureus." Molecules 26, no. 17 (August 31, 2021): 5288. http://dx.doi.org/10.3390/molecules26175288.

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Fish bones (FBs) are aquatic by-products that are sources of antioxidant-active peptides, calcium dietary supplements, and biomedical materials. Usually, fermentation of these by-products via microorganisms brings desirable changes, enhancing their value. This study investigates the value addition of FB when fermented with Monascus purpureus (MP) for different time intervals, such as 3 days (F3) and 6 days (F6). The results indicate that the soluble protein, peptide, amino acid and total phenol content, as well as the antioxidant capacity (DPPH, ABTS+ radical scavenging activity, and relative reducing power), of F3 and F6 were significantly increased after fermentation. Furthermore, the ROS contents of F3 and F6 were reduced to a greater extent than that of hydrogen peroxide (H2O2) in Clone-9 cells. The MMP integrity, as well as the SOD, CAT, and GPx activity, of F3 and F6 were also increased significantly compared to the H2O2 in Clone-9 cells. Notably, F3 and F6 displayed significant reductions in ROS content, as well as elevate, SOD activity and MMP integrity in Clone-9 cells, when compared with the native FB. These results indicate that the FBs fermented with MP for 3 days (F3), and 6 days (F6) have antioxidant capacity, with possible applications as natural food supplements.

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Hopf, Barbara, Bennet Fischer, Thomas Bosselmann, Alexander W. Koch, and Johannes Roths. "Strain-Independent Temperature Measurements with Surface-Glued Polarization-Maintaining Fiber Bragg Grating Sensor Elements." Sensors 19, no. 1 (January 3, 2019): 144. http://dx.doi.org/10.3390/s19010144.

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A novel technique for strain and temperature decoupling with surface-glued fiber Bragg gratings (FBGs) is presented and applied for strain-independent temperature measurements in a temperature range between −30 °C and 110 °C with uncertainties below 4 °C over the entire measurement range. The influence of temperature-dependent glue-induced transversal forces on the fiber sensor could be eliminated with a sensor element consisting of two FBGs in identical polarization-maintaining fibers that were spliced perpendicular to each other. After aligning and gluing the sensor element with its optical axes parallel and perpendicular to the specimen, the averaged Bragg wavelength shifts of both FBGs were proven to be independent of the glue’s influence and therefore independent of any change in the material characteristics of the glue, such as aging or creeping behavior. For the first time, this methodology enables temperature measurements with surface-attached bare FBGs independently of arbitrary longitudinal and glue-induced strains. This is of great value for all applications that rely on a fully glued sensor design, e.g., in applications with high electromagnetic fields, on rotating parts, or in vacuum for space applications.

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Chapalo, Ivan, Andrei Gusarov, Andreas Ioannou, Andreas Pospori, Karima Chah, Ying-Gang Nan, Kyriacos Kalli, and Patrice Mégret. "Online Gamma Radiation Monitoring Using Few-Mode Polymer CYTOP Fiber Bragg Gratings." Sensors 23, no. 1 (December 21, 2022): 39. http://dx.doi.org/10.3390/s23010039.

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We investigated the gamma radiation response of fiber Bragg gratings (FBGs) inscribed in a few-mode polymer optical fiber. The fiber had a graded-index CYTOP core of 20 µm and XYLEX overclad of 250 µm in diameter. Four FBGs were exposed to gamma radiation during four irradiation sessions at a 5.3 kGy/h dose rate. The FBGs showed a linear Bragg wavelength shift with the received dose with a mean sensitivity of −3.95 pm/kGy at 43 °C. The increased temperature provides a rise in the sensitivity: it reached −10.6 pm/kGy at 58 °C. After irradiation, the FBGs showed partial recovery, which increased with the received dose. Furthermore, the FBG’s reflection power decreased with the dose. This attenuation is mainly due to insertion losses caused by the radiation induced attenuation in the CYTOP fiber. Linear response to the received dose makes CYTOP FBGs attractive for gamma radiation dosimetry. However, temperature dependence of the sensitivity should be compensated in practical applications.

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Sönmezer, Dilek, Fatma Lati̇foğlu, Güler Toprak, Ayhan Düzler, and İsmail Alper İşoğlu. "Pericardial fluid and vascular tissue engineering: A preliminary study." Bio-Medical Materials and Engineering 32, no. 2 (March 23, 2021): 101–13. http://dx.doi.org/10.3233/bme-196014.

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BACKGROUND: The heart is surrounded by a membrane called pericardium or pericardial cavity. OBJECTIVE: In this study, we investigated the pericardial fluid (PF) for coating polycaprolactone (PCL) scaffolds. PFS, which is a PF component, was used for the coating material. In addition to using PFS for surface coating, MED and fetal bovine serum (FBS) were also used for comparison. METHODS: Pericardial fluid cells (PFSc) isolated from PF were cultured on coated PCL scaffolds for 1, 3, and 5 days. Cell viability was determined using 3-(4, 5-di-methylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. RESULTS: The MTT assay results showed that the viability of cells on PCL scaffold coated with PFS increased over time (P < 0.005), and cell viability was significantly different between PCL scaffolds coated with PFS and non-coated PCL scaffolds. However, cell viability was significantly higher in the PCL scaffolds coated with PFS than non-coated and coated with FBS, MED, and PCL scaffolds. Scanning electron microscopy (SEM) microscopy images and MTT assay indicated that PFSc are attached, proliferated, and spread on PCL scaffolds, especially on PCL scaffolds coated with PFS. CONCLUSIONS: These results suggest that PFS is a biocompatible material for surface modification of PCL scaffolds, which can be used as a suitable material for tissue engineering applications.

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Aimasso, A., M. D. L. Dalla Vedova, P. Maggiore, and G. Quattrocchi. "Study of FBG-based optical sensors for thermal measurements in aerospace applications." Journal of Physics: Conference Series 2293, no. 1 (June 1, 2022): 012006. http://dx.doi.org/10.1088/1742-6596/2293/1/012006.

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Abstract Optical fibers have revolutionized several technological sectors in recent decades, above all that of communication, and have also found many applications in the medical, lighting engineering, and infrastructural fields. In the aerospace field, many studies investigated the adoption of fiber optics considering the planned transition from fly-by-wire to fly-by-light flight controls. A significant feature of optical fiber is its ability to be used not only as a transmission medium but also as a basis for fiber-embedded sensors; one of the most prominent types is based on Bragg gratings (FBGs). FBGs can replace several traditional sensors, providing measures of temperature, vibrations, and mechanical deformation. Optical sensors provide many advantages over traditional, electrical-based sensors, including EMI insensitivity, ease of multiplexing on a single line, resilience to harsh environments, very compact sizes and global weight saving. Furthermore, punctual knowledge of the temperature field is essential to perform the thermal compensation of the optical sensors used for strain measurements. In this work, the authors analyzed the performance of thermal sensors based on FBGs to verify their stability, accuracy, and sensitivity to operating conditions. Two different methods of FBGs surface application have been considered (gluing with pre-tensioning vs. non-tensioned bonding). The results were then compared to those acquired using typical temperature sensors to determine the relationship between the observed temperature and the Bragg wavelength variation (i.e. the proportionality coefficient Kt). The effects on the proportionality coefficient Kt, arising from fiber pre-tensioning and thermal expansion of the structural support, were then evaluated by comparing the results obtained with the two bonding approaches.

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Chen, Shimeng, Chao Zhang, Jiahui Wang, Na Li, Yongxin Song, Haojun Wu, and Yun Liu. "A Fiber Bragg Grating Sensor Based on Cladding Mode Resonance for Label-Free Biosensing." Biosensors 13, no. 1 (January 6, 2023): 97. http://dx.doi.org/10.3390/bios13010097.

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A fiber-optic biosensing platform based on ultra-narrowband cladding mode resonances was developed on a high-reflectivity fiber Bragg grating (FBG) for targeting biomolecular detection. The multiple cladding modes with a high sensitivity to the refractive index (RI) were excited in the FBG by coupling between the forward-propagating guided core mode of the multimode fiber and the backward-propagating guided cladding mode of the FBG without any damage to the fiber structure or any change to the standard FBG manufacturing process. The full width at half maximum and the Q-factor of the typical cladding mode resonance operation of the proposed sensor are 80 pm and 19,270, respectively, which are better than those of most fiber-optic biosensors reported to date. In addition, the FBG sensor demonstrated a high sensitivity in protein detection and a high selectivity in serum sample assays. The sensitivity of this sensor was further increased simply by coating it with graphene oxide (GO) sheets on the sensing surface without using a signal amplification strategy. Furthermore, an ultra-low limit of detection (LOD) of 32 pM was obtained by the GO-coated FBG sensor for IgG detection. The proposed FBG sensor provides a competitive fiber-optic platform for biomolecular detection. It has a great potential for applications in label-free biosensing.

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Lakho, Rafique Ahmed, Zhang Yi-Fan, Jiang Jin-Hua, Hong Cheng-Yu, and Zamir Ahmed Abro. "A smart insole for monitoring plantar pressure based on the fiber Bragg grating sensing technique." Textile Research Journal 89, no. 17 (March 7, 2019): 3433–46. http://dx.doi.org/10.1177/0040517519833977.

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The analysis of plantar pressure distribution is essential in the field of biomedical and sports-related applications. In this study, a smart insole was developed for the measurement of plantar pressure distribution and the evaluation of body postures using optical fiber Bragg grating (FBG) sensing technology. Four FBG sensors characterized by four different center Bragg wavelengths, 1528 ± 0.3, 1532 ± 0.3, 1535 ± 0.3 and 1539 ± 0.3 nm, were located at the first metatarsus, third metatarsus, fifth metatarsus and heel position, respectively. The measurement sensitivity of all the FBG sensors was 0.000412 nm/kPa, approximately. Silica gel material of modulus = 10 MPa was selected to incorporate the FBG sensors. All FBG sensors were multiplexed together with one optical fiber cable. The performance and functional properties of all FBG-based pressure sensors were calibrated in the laboratory to evaluate plantar pressure distribution. A male subject was selected for performing four tasks, namely standing in an upright position, leaning forward, squat position and forward fold. During standing tests, plantar pressure observed at the heel position was around 57% higher than that at the first and third metatarsus, while the pressure of the fifth metatarsus position presents minimal pressure, which is only 37% that of the pressure of the heel position. When the subject performs leaning forward, the squat position and forward fold posture, the first and third metatarsi show maximum pressure, while the pressure decreases at the fifth metatarsus position. However, almost zero pressure is observed at the heel position when the subject changes the body postures of leaning forward, squat and forward fold posture. The extreme pressure of the forward fold posture was 1750 kPa acquired at the first metatarsus, which is 52% and 62% higher than those at the fifth and third metatarsi, respectively. Therefore, the smart insole successfully recorded both plantar pressure distribution and body posture changes regarding the wavelength values collected by the FBG sensors.

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Borotto, Marco, Enrico De Cais, Marco Belloli, Andrea Bernasconi, and Stefano Manzoni. "Metrological Performances of Fiber Bragg Grating Sensors and Comparison with Electrical Strain Gauges." Key Engineering Materials 495 (November 2011): 53–57. http://dx.doi.org/10.4028/www.scientific.net/kem.495.53.

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The fiber Bragg grating sensors (FBGs) have been recently introduced: they present a photorecord grating on the fiber itself, which allows the reflection of a certain wavelength of the input light spectrum. The applied strain is estimated relying on changes of the reflected wavelength. One of the possible applications that has prompted us to study this type of sensors is the possibility to create smart dynamometric structures based on carbon fiber by embedding FBGs. Many papers are available in literature about some applications with smart structures but there is not yet an appropriate metrological characterization about these FBG sensors, their strengths and weaknesses: for these reasons it was deemed useful making several tests on FBG sensors in terms of measurement accuracy, signal to noise ratio, ability to compensate for thermal effects and their behavior for dynamic applications. All these results have been compared to electrical strain gauge ones, which represent the actual reference strain measurement systems. The various solutions to compensate for thermal effects have offered several information for further analyses and the basis for a future use of these sensors for static or semi-static tests. Being fully aware of FBGs characteristics allows to draw down guidelines about their integration in composite materials for the most different applications, understanding in a better way the sensor response.

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Majewska, Katarzyna, Magdalena Mieloszyk, and Wieslaw Ostachowicz. "Application of FBGs Grids for Damage Detection and Localisation." Applied Mechanics and Materials 70 (August 2011): 375–80. http://dx.doi.org/10.4028/www.scientific.net/amm.70.375.

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Structural Health Monitoring (SHM) technology allows significant improvement of safety of structures and ecological awareness. SHM systems allow users to reduce maintenance costs which are directly connected with non-destructive techniques used for monitoring of important structures. In this paper Authors present an applications of Fibre Bragg Gratings (FBGs) for damage detection and damage localisation in isotropic beam. FBGs sensors are excellent tools for evaluating conditions of a structure due to their sensitivity, small size and weight as well the immunity of the sensors to electromagnetic field interferences.

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Chaoui, Fahd, Otman Aghzout, Mounia Chakkour, and Mounir El Yakhloufi. "Apodization Optimization of FBG Strain Sensor for Quasi-Distributed Sensing Measurement Applications." Active and Passive Electronic Components 2016 (2016): 1–8. http://dx.doi.org/10.1155/2016/6523046.

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A novel optimized apodization of Fiber Bragg Grating Sensor (FBGS) for quasi-distributed strain sensing applications is developed and introduced in this paper. The main objective of the proposed optimization is to obtain a reflectivity level higher than 90% and a side lobe level around −40 dB, which is suitable for use in quasi-distributed strain sensing application. For this purpose, different design parameters as apodization profile, grating length, and refractive index have been investigated to enhance and optimize the FBGS design. The performance of the proposed apodization has then been compared in terms of reflectivity, side lobe level (SLL), and full width at half maximum (FWHM) with apodization profiles proposed by other authors. The optimized sensor is integrated on quasi-distributed sensing system of 8 sensors demonstrating high reliability. Wide strain sensitivity range for each channel has also been achieved in the quasi-distributed system. Results prove the efficiency of the proposed optimization which can be further implemented for any quasi-distributed sensing application.

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Faustov, A., P. Saffari, C. Koutsides, A. Gusarov, M. Wuilpart, P. Megret, K. Kalli, and L. Zhang. "Highly Radiation Sensitive Type IA FBGs for Future Dosimetry Applications." IEEE Transactions on Nuclear Science 59, no. 4 (August 2012): 1180–85. http://dx.doi.org/10.1109/tns.2012.2202247.

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Kulchin, Yuriy N., Anatoly M. Shalagin, Oleg B. Vitrik, Sergey A. Babin, Anton V. Dyshlyuk, and Alexander A. Vlasov. "Differential Reflectometry of Fiber Bragg Gratings." Key Engineering Materials 437 (May 2010): 324–28. http://dx.doi.org/10.4028/www.scientific.net/kem.437.324.

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A reflectometric approach is proposed for interrogation of multiple fiber Bragg grating (FBG) sensors recorded in a single fiber optic line, based on the differential registration FBGs’ response to a short probing laser pulse using conventional OTDR. A special optical layout has been developed allowing transformation of FBG’s spectrally modulated signals into intensity modulated signals and at the same time eliminating the susceptibility of the system to light power fluctuations. Threshold sensitivity of the method amounted to ~50 μstrain within the measurement range of ~4000 μstrain. The maximum number of FBGs interrogated by the proposed technique is estimated at several hundred, which by far surpasses the requirements of most practical applications. Due to its simplicity, efficiency and usage of conventional OTDR equipment the proposed FBG interrogation technique can find a wide range of applications, in particular in structural health monitoring.

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Zhang, Naizhong, Claire Davis, Wing K. Chiu, Tommy Boilard, and Martin Bernier. "Fatigue Performance of Type I Fibre Bragg Grating Strain Sensors." Sensors 19, no. 16 (August 12, 2019): 3524. http://dx.doi.org/10.3390/s19163524.

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Although fibre Bragg gratings (FBGs) offer obvious potential for use in high-density, high-strain sensing applications, the adoption of this technology in the historically conservative aerospace industry has been slow. There are several contributing factors, one of which is variability in the reported performance of these sensors in harsh and fatigue prone environments. This paper reports on a comparative evaluation of the fatigue performance of FBG sensors written according to the same specifications using three different grating manufacturing processes: sensors written in stripped and re-coated fibres, sensors written during the fibre draw process and sensors written through fibre coating. Fatigue cycling of the fibres is provided by a customized electro-dynamically actuated loading assembly designed to provide high frequency and amplitude loading. Pre- and post-fatigue microscopic analysis and high-resolution transmission and reflection spectra scanning are conducted to investigate the fatigue performance of FBGs, the failure regions of fibres as well as any fatigue-related effects on the spectral profiles. It was found that because of the unique fabrication method, the sensors written through the fibre coating, also known as trans-jacket FBGs, show better fatigue performance than stripped and re-coated FBGs with greater control possible to tailor the optical reflection properties compared to gratings written in the draw tower. This emerging method for inscription of Type I gratings opens up the potential for mass production of higher reflectivity, apodised sensors with dense or complex array architectures which can be adopted as sensors for harsh environments such as in defence and aerospace industries.

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Meng, Lijun, Xin Tan, and Quanquan Yu. "Study on Time-frequency Imaging of Ultrasonic Detection with Phase Shifted Fiber Bragg Grating Sensing." Measurement Science Review 23, no. 3 (June 1, 2023): 106–15. http://dx.doi.org/10.2478/msr-2023-0014.

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Abstract The influence of the wavelength difference between the laser source and the phase-shifted fiber Bragg grating (PS-FBG) on the intensity of the power demodulation system based on an adjustable laser source was studied experimentally, and the optimum of the output laser wavelength was determined. Then, the research on time-frequency imaging damage identification based on smooth pseudo-Wigner-Ville distribution was carried out. The Time of Flight of the acoustic wave signal was calculated and time compensation was made according to the Wigner-Ville distribution and the Lamb wave dispersion curve. The ultrasonic waves before and after damage were measured with spatially arranged PS-FBGs. The difference signals were processed in a window, and then the time-frequency energy of the normalized difference signal was imaged to assess the damage detection and location. Although the mode and group velocity of ultrasound measured by each fiber grating were different, the accurate location and identification of artificial damage in an aluminum alloy plate was realized by using only three PS-FBGs and a smooth Wigner time-frequency imaging method.

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Radzi, Nurnazifah M., Amirah A. Latif, Mohammad F. Ismail, Josephine Y. C. Liew, Noor A. Awang, Han K. Lee, Fauzan Ahmad, Siti F. Norizan, and Harith Ahmad. "Tunable Spacing Dual-Wavelength Q-Switched Fiber Laser Based on Tunable FBG Device." Photonics 8, no. 12 (November 23, 2021): 524. http://dx.doi.org/10.3390/photonics8120524.

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A tunable spacing dual-wavelength Q-switched fiber laser is experimentally demonstrated based on a fiber Bragg grating tunable device incorporated in an erbium-doped fiber laser (EDFL). The system utilizes two identical fiber Bragg gratings (FBGs) at 1547.1 nm origin to enable two laser lines operation. The wavelength separations between two laser lines are controlled by fixing one of the FBGs while applying mechanical stretch and compression to the other one, using a fiber Bragg grating tunable device. The seven steps of wavelength spacing could be tuned from 0.3344 to 0.0469 nm spacing. Pulse characteristics for both close and wide spacing of dual-wavelength Q-switched fiber laser are successfully being recorded. The findings demonstrate the latest idea of dual-wavelength fiber laser based on FBG tunable device, which offers a wide range of future applications.

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Portosi, Vincenza, Dario Laneve, Mario Christian Falconi, and Francesco Prudenzano. "Advances on Photonic Crystal Fiber Sensors and Applications." Sensors 19, no. 8 (April 21, 2019): 1892. http://dx.doi.org/10.3390/s19081892.

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In this review paper some recent advances on optical sensors based on photonic crystal fibres are reported. The different strategies successfully applied in order to obtain feasible and reliable monitoring systems in several application fields, including medicine, biology, environment sustainability, communications systems are highlighted. Emphasis is given to the exploitation of integrated systems and/or single elements based on photonic crystal fibers employing Bragg gratings (FBGs), long period gratings (LPGs), interferometers, plasmon propagation, off-set spliced fibers, evanescent field and hollow core geometries. Examples of recent optical fiber sensors for the measurement of strain, temperature, displacement, air flow, pressure, liquid-level, magnetic field, and hydrocarbon detection are briefly described.

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Zheng, Jilin, Rong Wang, Tao Pu, Lin Lu, Tao Fang, Yang Su, Ling Li, and Xiangfei Chen. "Phase-controlled superimposed FBGs and their applications in spectral-phase en/decoding." Optics Express 19, no. 9 (April 18, 2011): 8580. http://dx.doi.org/10.1364/oe.19.008580.

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Ross, Michael, R. Jenkins, Charles Nelson, and Peter Joyce. "High Temperature Effects during High Energy Laser Strikes on Embedded Fiber Bragg Grating Sensors." Sensors 19, no. 6 (March 23, 2019): 1432. http://dx.doi.org/10.3390/s19061432.

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As the applications of fiber Bragg gratings (FBGs) continue to grow and become more advanced, it becomes necessary to understand their behavior when exposed to high temperatures in unique situations. In these experiments, uniform 1530-nm fiber Bragg gratings and Type K Cr-Al thermocouples were embedded in three-ply carbon fiber composites. A 100 W high energy laser (HEL) heated the composites to high temperatures over timespans less than one second, and FBG spectral data and thermocouple temperature data were collected during each HEL heating test. The data from three high energy laser tests that represent different levels of damage to the FBG are analyzed to explore the spectral response and thermal decay of embedded FBG sensors when exposed to high temperatures over short timespans. Results are compared to a previously proposed power-law model describing the decay of FBGs in bare fiber when held at constant temperatures over much longer timespans.

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Qu, Hang, Weiyuan Huang, Zhoupeng Lin, Xin Cheng, Rui Min, Chuanxin Teng, Christophe Caucheteur, and Xuehao Hu. "Influence of Annealing on Polymer Optical Fiber Bragg Grating Inscription, Stability and Sensing: A Review." Sensors 23, no. 17 (August 31, 2023): 7578. http://dx.doi.org/10.3390/s23177578.

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This article reviews recent research progress on the annealing effects on polymer optical fibers (POFs), which are of great importance for inscription, stability and sensing applications of fiber Bragg gratings (FBGs) in POFs due to their unique properties related to polymer molecular chains. In this review, the principle of annealing to reduce frozen-in stress in POFs drawing and different annealing timings are firstly summarized. Then, the annealing methods for POFs are introduced under several different conditions (temperature, humidity, strain, stress and solution). Afterwards, the principle of FBGs and several inscription techniques are reported. Subsequently, the annealing effects on the properties of POFs and polymer optical fiber Bragg gratings (POFBGs) quality are discussed. Finally, the influence of annealing on POFBG sensitivity is summarized. Overall, this paper provides a comprehensive overview of annealing techniques and their impact on both POFs and POFBGs. We hope that it will highlight the important progress made in this field.

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Castaldo, A., M. A. Caponero, P. Clemente, C. Mazzotta, A. Polimadei, G. Terranova, M. Capasso, et al. "Strain and vibration measurements by FBG sensors for engineering applications." Journal of Instrumentation 18, no. 06 (June 1, 2023): C06030. http://dx.doi.org/10.1088/1748-0221/18/06/c06030.

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Abstract Fiber optic sensors based on the fiber Bragg grating (FBG) technology [1] is widely used to produce quasi-distributed monitoring systems to measure mechanical parameters for Structural Health Monitoring (SHM) of civil engineering structures [2]. FBG sensors are produced in the core of the optical fiber, as a short segment of fiber where a diffraction grating is produced (5–10 mm). The principle of operation of the FBGs is based on the diffraction occurring at the grating: if broadband light propagates, a quasi-monochromatic counter propagating light originates. The wavelength of the diffracted light depends on the value of the refraction index of the core along the grating which in turn is affected by both temperature and strain. Thus, by measuring the wavelength change of the counter propagating light, the change of strain and the temperature can be worked out. The PREFOS Project [3] aims to develop a novel procedure to apply the use of FBGs to monitor the prestressed strands of civil engineering prefabricated components. In this paper, we report results of an experimental campaign intended to measure the sensitivity of saddle-like sensors to induced vibration and mechanical strain. Measurements were done performing static and dynamic tests on a steel strand equipped with 3 sensors. The tests have been performed applying different tensioning to the steel strand. Static measurements were worked out applying a stepwise tensioning increase. Dynamic tests were worked out at each stepped tension level, inducing vibration by both sharp hammer impact and release of hanged weight. The paper is organized as follows, in section 1 a general description of the testbed structure used for the experiments will be provided. In section 2 the results of static analysis and dynamic tests will be presented with the dynamic behavior of the strand evaluated by performing a simple Fast Fourier Transform (FFT). Finally, the conclusions will be drawn.

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Liu, Rong Mei, Da Kai Liang, and Xing Liu Hu. "Simultaneous Force and Temperature Sensor Using Small-Diameter FBGs." Applied Mechanics and Materials 83 (July 2011): 274–79. http://dx.doi.org/10.4028/www.scientific.net/amm.83.274.

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In order to decrease the influence on mechanical performance of smart composite, small diameter optical fibers are usually preferred as strain sensors. Therefore, fiber Bragg gratings in small diameter were manufactured. In applications, the FBG measures both strain (or force, pressure, displacement) and thermal expansion. In order to overcome this inconvenience and to measure both parameters at the same time and location, a simple temperature insensitive force sensor was proposed. A pair of small-diameter FBG was attached on a uniform strength beam. One of the FBG was affixed on the upper surface of the cantilever, and the other one on the bottom. The central wavelength shifts of the two FBGs are proportional to load value F and –F respectively. Therefore, coefficient matrix is well conditioned. The force and temperature in sensing point could be discriminated. Experiments were carried out to study the force and temperature cross sensitivity. Experimental results match the theoretical ones well. The temperature and force were calculated and the errors were 2% and 7% respectively.

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Heilmeier, Florian, Robert Koos, Michael Singer, Constantin Bauer, Peter Hornberger, Jochen Hiller, and Wolfram Volk. "Evaluation of Strain Transition Properties between Cast-In Fibre Bragg Gratings and Cast Aluminium during Uniaxial Straining." Sensors 20, no. 21 (November 4, 2020): 6276. http://dx.doi.org/10.3390/s20216276.

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Current testing methods are capable of measuring strain near the surface on structural parts, for example by using strain gauges. However, stress peaks often occur within the material and can only be approximated. An alternative strain measurement incorporates fibre-optical strain sensors (Fiber Bragg Gratings, FBG) which are able to determine strains within the material. The principle has already been verified by using embedded FBGs in tensile specimens. The transition area between fibre and aluminium, however, is not yet properly investigated. Therefore, strains in tensile specimens containing FBGs were measured by neutron diffraction in gauge volumes of two different sizes around the Bragg grating. As a result, it is possible to identify and decouple elastic and plastic strains affecting the FBGs and to transfer the findings into a fully descriptive FE-model of the strain transition area.We thus accomplished closing the gap between the external load and internal straining obtained from cast-in FBG and generating valuable information about the mechanisms within the strain transition area.It was found that the porosity within the casting has a significant impact on the stiffness of the tensile specimen, the generation of excess microscopic tensions and thus the formation of permanent plastic strains, which are well recognized by the FBG. The knowledge that FBG as internal strain sensors function just as well as common external strain sensors will now allow for the application of FBG in actual structural parts and measurements under real load conditions. In the future, applications for long-term monitoring of cast parts will also be enabled and are currently under development.

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Dostovalov, Alexander V., Alexey A. Wolf, Kirill A. Bronnikov, Mikhail I. Skvortsov, Alexey E. Churin, and Sergey A. Babin. "Femtosecond Pulse Structuring of Multicore Fibers for Development of Advanced Fiber Lasers and Sensors." Solid State Phenomena 312 (November 2020): 221–26. http://dx.doi.org/10.4028/www.scientific.net/ssp.312.221.

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In this paper we investigate the fiber Bragg grating (FBG) arrays selectively inscribed in a multicore fiber for a different sensor and laser applications. Particularly, wavelength-switchable and tunable fiber laser was realized based on uniform and non-uniform FBGs precisely positioned in the selected cores. A quasi-distributed 3D shape sensor based on FBG array inscribed in a multicore fiber with helically twisted side cores was fabricated and applied for shape reconstruction of papillotome.

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Grobnic, Dan, Cyril Hnatovsky, Sergey Dedyulin, Robert B. Walker, Huimin Ding, and Stephen J. Mihailov. "Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing." Sensors 21, no. 4 (February 19, 2021): 1454. http://dx.doi.org/10.3390/s21041454.

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High-temperature-resistant fiber Bragg gratings (FBGs) are the main competitors to thermocouples as sensors in applications for high temperature environments defined as being in the 600–1200 °C temperature range. Due to their small size, capacity to be multiplexed into high density distributed sensor arrays and survivability in extreme ambient temperatures, they could provide the essential sensing support that is needed in high temperature processes. While capable of providing reliable sensing information in the short term, their long-term functionality is affected by the drift of the characteristic Bragg wavelength or resonance that is used to derive the temperature. A number of physical processes have been proposed as the cause of the high temperature wavelength drift but there is yet no credible description of this process. In this paper we review the literature related to the long-term wavelength drift of FBGs at high temperature and provide our recent results of more than 4000 h of high temperature testing in the 900–1000 °C range. We identify the major components of the high temperature wavelength drift and we propose mechanisms that could be causing them.

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Theodosiou, Antreas, Jan Aubrecht, Ivan Kašík, Daniel Dousek, Matěj Komanec, and Kyriacos Kalli. "Femtosecond Laser Plane-by-Plane Inscribed Cavity Mirrors for Monolithic Fiber Lasers in Thulium-Doped Fiber." Sensors 21, no. 6 (March 10, 2021): 1928. http://dx.doi.org/10.3390/s21061928.

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A monolithic fiber laser operating in the short wavelength infrared that is suitable for CO2 gas sensing applications is proposed and presented. The current study reports a laser design based on the direct inscription of a monolithic Fabry–Perot (FP) cavity in a thulium-doped optical fiber using the femtosecond laser (FsL) plane-by-plane inscription method to produce the cavity mirrors. The FP cavity was inscribed directly into the active fiber using two wavelength-identical fiber Bragg gratings (FBGs), one with high and one with low reflectivity. Initially the effective length of the fiber was defined using a single high reflectivity FBG and subsequently a very weak FBG was inscribed at the other end of the fiber in order to demonstrate a fully monolithic fiber laser. All fiber lasers were designed for continuous wave operation at 1950 nm and characterized with respect to the power output, slope efficiency, stability, and effective resonator length. The performance of the presented monolithic laser cavities was evaluated using the same active fiber as a reference fiber spliced to FBGs inscribed in passive fiber; an improvement exceeding 12% slope efficiency is reported for the presented monolithic laser.

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Pereira, Luís, Rui Min, Getinet Woyessa, Ole Bang, Carlos Marques, Humberto Varum, and Paulo Antunes. "Interrogation Method with Temperature Compensation Using Ultra-Short Fiber Bragg Gratings in Silica and Polymer Optical Fibers as Edge Filters." Sensors 23, no. 1 (December 20, 2022): 23. http://dx.doi.org/10.3390/s23010023.

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The use of simpler and less bulky equipment, with a reliable performance and at relative low cost is increasingly important when assembling sensing configurations for a wide variety of applications. Based on this concept, this paper proposes a simple, efficient and relative low-cost fiber Bragg grating (FBG) interrogation solution using ultra-short FBGs (USFBGs) as edge filters. USFBGs with different lengths and reflection bandwidths were produced in silica optical fiber and in poly(methyl methacrylate) (PMMA) microstructured polymer optical fiber (mPOF), and by adjusting specific inscription parameters and the diffraction pattern, these gratings can present self-apodization and unique spectral characteristics suitable for filtering operations. In addition to being a cost-effective edge filter solution, USFBGs and standard uniform FBGs in silica fiber have similar thermal sensitivities, which results in a straightforward operation without complex equipment or calculations. This FBG interrogation configuration is also quite promising for dynamic measurements, and due to its multiplexing capabilities multiple USFBGs can be inscribed in the same optical fiber, allowing to incorporate several filters with identical or different spectral characteristics at specific wavelength regions in the same fiber, thus showing great potential to create and develop new sensing configurations.

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Jonathan, Enock. "Light synthesis with linearly chirped fibre Bragg gratings (FBGs) for optical coherence tomography (OCT) applications." Optics Communications 252, no. 1-3 (August 2005): 64–72. http://dx.doi.org/10.1016/j.optcom.2005.04.009.

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Chen, Jeson, Si-Yu Huang, Cheng-Yu Lin, and Wen-Fung Liu. "A Low-Frequency Magnetic Field Sensor Based on Fiber Bragg Gratings." Photonics 9, no. 2 (February 11, 2022): 102. http://dx.doi.org/10.3390/photonics9020102.

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A new type of low-frequency magnetic-field sensor based on fiber Bragg gratings (FBGs) was experimentally demonstrated for measuring the DC to low-frequency magnetic field. The operating mechanism of this AC magnetic sensor is based on the strain exerted by a loaded magnet on the sensing structure, which causes center-wavelength shifts of FBG. The achieved sensitivity was 8.16 pm/G with a resolution of 3 Gauss at ambient conditions. The proposed FBG magnetic sensor is easy to use, compact, and suitable for DC to low-frequency magnetic sensing applications.

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Journal articles on the topic 'Biomedical applications of FBGs'

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