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High-precision FBG demodulation using amplitude ratio curve with sharp peak
摘要： For the fiber Bragg grating (FBG) sensor based on the reflection peak position searching demodulation algorithms, a key problem is that the demodulation precision of measurement signal is seriously limited by the full width half maximum (FWHM) of the FBG reflection spectrum. In this paper, in order to overcome this problem and enhance the measurement precision, we proposed a high-precision demodulation method based on amplitude ratio curve to instead of the FBG reflection spectrum, which can increase the sensing precision significantly. In this method, the Bragg wavelength of FBG is modulated periodically with a sinusoidal function to obtain a series of reflection spectra. Then at each wavelength the amplitude ratio between second harmonic frequency component and fundamental frequency component is calculated to create the amplitude ratio curve. Here, we present a comprehensive theoretical analysis and experimental demonstration to verify the advantages of this method. Comparing with the demodulation method based on the FBG reflection spectrum, the average maximum measure error (MME) of Bragg wavelength is reduced from ± 1.54 pm to ± 0.15 pm, which improved by 10.3 times. In addition, the influence of the modulation amplitude and sampling frequency on demodulation accuracy are also studied in this paper.
关键词： Amplitude ratio curve,High precision temperature measurement,Fiber Bragg grating
更新于2025-09-23 15:23:52
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Deformation sensing and electrical compensation of smart skin antenna structure with optimal fiber Bragg grating strain sensor placements
摘要： Skin antenna structure is a kind of multifunctional composite structure in which printed antennas are integrated. This paper proposes a new smart skin antenna structure with embedded fiber Bragg grating (FBG) strain sensors. Utilizing the measured strains from limited FBG strain sensors, the deformation shapes are reconstructed by using a strain–displacement transformation, and the deteriorated radiation patterns caused by the deformations are compensated by using a strain-electromagnetic coupling mode which is derived and validated for the first time in the paper. Moreover, a two-step sensor placement method considering the information redundancy is proposed to determine optimal FBG strain sensor locations. The comparisons show that the two-step sensor placement method is advantageous in terms of the sensor distribution and computational cost. The fabrication process of the smart skin antenna structure was presented, and an experimental system with optimal sensor placements was developed. The measured results demonstrate that the reconstructed shapes agree well with the real ones, and that the deteriorated radiating patterns were almost completely restored to the desired ones. The proposed smart skin antenna structure which can provide the electromagnetic receiving-sending, structural deformation monitoring and electrical correction functions has a potential application prospect in the future mobile vehicle.
关键词： Fiber Bragg grating,Deformation sensing,Electrical compensation,Smart skin antenna,Optimal sensor placement
更新于2025-09-23 15:23:52
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AIP Conference Proceedings [Author(s) 4TH ELECTRONIC AND GREEN MATERIALS INTERNATIONAL CONFERENCE 2018 (EGM 2018) - Bandung, Indonesia (27–28 July 2018)] - Design and analysis of fiber Bragg grating tunable filter utilizing thermal technique
摘要： In this paper a tunable filter based on fiber Bragg grating (FBG) utilizing thermal technique is theoretically investigated and experimentally validated. According to the results, a tuning range is achieved about 1.5 nm in C-band region. While, for L-band region the wavelength shift is slightly greater than in the C-band region about 1.6 nm. This shifting is due to changing in thermo-optic and thermal expansion of fiber, which causes changing in refractive index and then Bragg wavelength. The experimental validation is done at wavelength 1552.7 nm, the tunability is about 1.2428 nm when the temperature is varied from 21°C to 61°C.
关键词： thermal expansion,fiber Bragg grating,thermo-optic effect,thermal technique,tunable filter
更新于2025-09-23 15:23:52
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Fiber Bragg grating-based experimental and numerical investigations of CO <sub/>2</sub> migration front in saturated sandstone under subcritical and supercritical conditions
摘要： Carbon dioxide (CO2) can be at risk of leakage during its storage in deep saline aquifers due to stress field changes in the reservoir. The aim of this study was to investigate the effects of CO2 injection pressure on dynamic strain response of the reservoir and the CO2 migration process. A series of core flooding experiments was performed with the-state-of-art fiber Bragg grating sensors. The results show that the surface strain response was linearly correlated with CO2 injection pressure. Carbon dioxide migration velocity can be estimated from the strain response time differences among three gratings. The migration velocity of supercritical CO2 is higher than that of liquid CO2 but lower than gaseous CO2. Finally, numerical simulation was applied to model the CO2 migration process and the simulated values were compatible with those of experiments.
关键词： reservoir sandstone,core flooding,CO2 geological storage,CO2 migration front,fiber Bragg grating,strain response
更新于2025-09-23 15:23:52
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A novel fiber Bragg grating system for eye tracking
摘要： Eye movement evaluation is vital for diagnosis of various ophthalmological and neurological disorders. The present study proposes a novel, noninvasive, wearable device to acquire the eye movement based on a Fiber Bragg Grating (FBG) Sensor. The proposed Fiber Bragg Grating Eye Tracker (FBGET) can capture the displacement of the eyeball during its movements in the form of strain variations on a cantilever. The muscular displacement generated by the eyeball over the lower eyelid, by its swiveling action while moving the gaze on a target object, is converted into strain variations on a cantilever. The developed FBGET is investigated for dynamic tracking of the eye- gaze movement for various actions of the eye such as fixations, saccades and main sequence. This approach was validated by recording the eye movement using the developed FBGET as well as conventional camera-based eye tracker methodology simultaneously. The experimental results demonstrate the feasibility and the real-time applicability of the proposed FBGET as an eye tracking device. In conclusion, the present study illustrates a novel methodology involving displacement of lower eyelid for eye tracking application along with the employment of FBG sensors to carry out the same. The proposed FBGET can be utilized in both clinical and hospital environment for diagnostic purposes owing to its advantages of wear-ability and ease of implementation making it a point of care device
关键词： Eye Tracker,Fiber Bragg Grating Sensor,Eye muscular movement detection
更新于2025-09-23 15:23:52
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[IEEE 2018 3rd International Conference On Internet of Things: Smart Innovation and Usages (IoT-SIU) - Bhimtal (2018.2.23-2018.2.24)] 2018 3rd International Conference On Internet of Things: Smart Innovation and Usages (IoT-SIU) - Fiber Bragg Grating basedLandslide Early Warning System
摘要： Landslides are natural hazards which are known to cause loss of life and infrastructural damage. Landslide Early Warning System (LEWS) is intended to predict the occurrence of the landslide which provides ample time to initiate necessary protective measures. In the present study, a Fiber Bragg Grating (FBG) sensor based vibration sensor which can acquire the seismic vibrations is proposed as an LEWS. The proposed Fiber Bragg Grating Vibration Sensor (FBGVS) works on a specially designed cantilever structure, through which the seismic vibrations can be obtained in the form of strain variations on the cantilever. The strain variations over the cantilever will be acquired by the FBG sensor bonded over it. The cantilever is specially designed such that the strain sensitivity of the FBGVS is enhanced, by the appending of torsional strain along with the axial strain. Experimental trials have been carried out which prove the efficacy of the FBGVS to acquire the seismic vibrations. FBGVS acts as the sensing element for an IoT system to ensure the landslide warning signal is transmitted to all remote locations, effectively making an efficient LEWS.
关键词： Fiber Bragg grating sensor,Landslide Early Warning System,Fiber Bragg Grating Vibration Sensor
更新于2025-09-23 15:22:29
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Fibre Bragg grating sensor applications for structural health monitoring
摘要： Purpose – Structural health monitoring (SHM) has become an attractive subject in aerospace engineering ?eld considering the opportunity to avoid catastrophic failures by detecting damage in advance and to reduce maintenance costs. Fibre Bragg Grating (FBG) sensors are denoted as one of the most promising sensors for SHM applications as they are lightweight, immune to electromagnetic effects and able to be embedded between the layers of composite structures. The purpose of this paper is to research on and demonstrate the feasibility of FBG sensors for SHM of composite structures. Design/methodology/approach – Applications on thin composite beams intended for SHM studies are presented. The sensor system, which includes FBG sensors and related interrogator system, and manufacturing of the beams with embedded sensors, are detailed. Static tension and torsion tests are conducted to verify the effectiveness of the system. Strain analysis results obtained from the tests are compared with the ones obtained from the ?nite element analyses conducted using ABAQUS? software. In addition, the comparison between the data obtained from the FBG sensors and from the strain gauges is made by also considering the noise content. Finally, fatigue test under torsion load is conducted to observe the durability of FBG sensors. Findings – The results demonstrated that FBG sensors are feasible for SHM of composite structures as the strain data are accurate and less noisy compared to that obtained from the strain gauges. Furthermore, the convenience of obtaining reliable data between the layers of a composite structure using embedded FBG sensors is observed. Practical implications – Observing the advantages of the FBG sensors for strain measurement will promote using FBG sensors for damage detection related to the SHM applications. Originality/value – This paper presents applications of FBG sensors on thin composite beams, which reveal the suitability of FBG sensors for SHM of lightweight composite structures.
关键词： Torsion test,Tension test,Structural health monitoring,Composite beams,Fibre Bragg grating sensors
更新于2025-09-23 15:22:29
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Experimental Research on Sensing Characteristics of Adhesive-encapsulated FBG under Alcohol-disinfection Environment
摘要： Fiber Bragg grating (FBG) has proven to be the most suitable sensing element for force feedback of surgical robots because of its special advantages such as small size and physical robustness. In current reports, researchers packaged FBGs in surgical instrument by attaching them to external surface or embedding into shaft grooves by using adhesive because its good liquidity and operability compared with other packaging methods such as metal package and glass solder package, and the adhesive is often without covering because strict space requirement of tiny surgical instruments. However, due to the need of repeated disinfection, surgical instruments have to be exposed to chemical disinfectant excessively, which may leads to chronic corrosion of adhesive, and thus influences the sensing characteristics of the integrated FBGs. To address this concern, this paper investigates the sensing characteristics of adhesive-encapsulated FBG under disinfection environment. We simulated a common disinfection environment by using 75% alcohol, and three adhesive-encapsulated FBGs were soaked in it for long term. The sensing performances of FBGs have been tested periodically and the experimental results demonstrate that the FBGs are available with good sensing characteristics within the first 50 days. While after 50 days, the sensing performances of the three FBGs become worse gradually, and finally the adhesive layers of the three FBGs completely detached from the specimen in the 75th day, 80th day and 95th day, respectively. We hope the investigation could provide valuable reference for better application of FBG in force feedback of surgical robots.
关键词： Fiber Bragg grating (FBG),robot sensing,force feedback,alcohol-disinfection environment,surgical robot
更新于2025-09-23 15:22:29
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Effect of Different Inorganics on Polyimide-based Bragg Grating Humidity Sensor
摘要： Effect of activated carbon and lithium chloride on polyimide-based fiber Bragg Grating relative humidity sensor has been experimentally investigated. Through dip coating process, organic-inorganic hybrid coatings were deposited on fiber Bragg grating to form different relative humidity sensors. Experimental results show that the addition of activated carbon or lithium chloride alone could increase the humidity sensitivity (1.67 times and 1.61 times, respectively), but the structure which contains both lithium chloride and activated carbon increases the sensitivity most (3.9 times). In the 14-day stability test, the fluctuation of pure polyimide sensor is ± 6.5%, while the ones of activated carbon sensor, lithium chloride sensor, activated carbon and lithium chloride sensor are ± 3%, ± 8%, and ± 1.6%.
关键词： lithium chloride,fiber Bragg grating,activated carbon,polyimide,humidity sensor
更新于2025-09-23 15:22:29
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Tilted Fiber Bragg Grating Sensor Using Chemical Plating of a Palladium Membrane for the Detection of Hydrogen Leakage
摘要： A tilted ?ber Bragg grating (TFBG) hydrogen sensor coated with a palladium (Pd) membrane by the electroless plating method is proposed in this paper. A uniform layer of Pd metal is fabricated in aqueous solutions by the chemical coating method, which is used as the sensitive element to detect the change of the surrounding refractive index (SRI) caused by hydrogen absorption. The change in SRI causes an unsynchronized change of the cladding modes and the Bragg peak in the TFBG transmission spectrum, thereby eliminating the cross-sensitivity due to membrane expansion and is able to simultaneously monitor the presence of cracks in the pipe, as well as the hydrogen leakage. By subtracting the wavelength shift caused by ?ber expansion, the change of SRI, i.e., the information from the H2 level, can be separately obtained. The drifted wavelength is measured for the H2 concentration below the hydrogen explosion limit between 1% and 4%. The chemical-based coating has the advantages of a low cost, a simple operation, and being suitable for coating on long ?ber structures. The proposed sensor is able to detect the H2 signal in 5 min at a 1% H2 concentration. The proposed sensor is proved to be able to monitor the hydrogen level without the cross-sensitivity of temperature variation and expansion strains, so could be a good candidate for security applications in industry.
关键词： electroless plating,tilted ?ber Bragg grating,optical ?ber hydrogen sensor,palladium membrane
更新于2025-09-23 15:22:29