Effectiveness and optimization of fiber Bragg grating sensor as embedded strain sensor

Tang, Liqun; Tao, Xiaoming; Choy, Chung-loong

doi:10.1088/0964-1726/8/1/017

Cited by 21 publications

(10 citation statements)

References 22 publications

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“…By considering the effects of the strain-optic relationship, the axial strain e induced shift of Bragg wavelength is [15) ' or where E, , -2 are the axial strain and the transverse strain of the fiber, respectively, p j j and p, are the components of the strain-optic tensor, a' is the isothermal expansion coefficient, ~' is a thermo-optic constant of the optic fiber [ 15J (for silica, a' = 0.55 X 10'~, ~ = 8.3 X 10-6), and f and ~' are the strain sensitivity and thermal sensitivity, respectively. ' Equation 3 shows that the Bragg wavelength A change's linearly with the temperature variation (3T) and axial strain of the Bragg grating (E, ), which was confirmed by our previous studies [1~¡ 14,15]. Obviously, the strain sensitivity f is a function of material properties and the strained state of the fiber.…”

Section: Theoretical Fbg Sensorssupporting

confidence: 71%

Tangential Load Measurements by a Smart Textile Composite

Bin

Tao

et al. 2004

Textile Research Journal

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A cellular textile composite structure integrated with fiber Bragg grating (FBG) sensors is designed for tangential load distribution measurements. The composite consists of many cylindrical shell cells for which a unit cell is fabricated from polyester and glass woven fabrics and epoxy. FBG sensors are bonded on the surface of the cells. The feasibility of using this cellular composite to measure tangential load distribution is demonstrated by experiments. The strain induced wavelength shift in the FBG sensor has a linear relationship with the tangential force within a definite range. Numerical simulations are created by finite element analysis. The influences of the environmental temperature, thickness, and effective moduli of the composite and the influences of the position and direction of the FBG sensors are discussed. The sensitivities of this device are 0.09 nm/N (for PET tension), 0.05 nm/N (for PET '

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Section: Theoretical Fbg Sensorssupporting

confidence: 71%

Tangential Load Measurements by a Smart Textile Composite

Bin

Tao

et al. 2004

Textile Research Journal

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“…The induced shift of the Bragg wavelength is given by [ 14] or where E~, E2 are the axial strain and the transverse strain of fiber, respectively, p , j and p, 2 are components of the strain-optic tensor, a' is the isothermal expansion coefficient, ~' is regarded as a thermo-optic constant of the optic fiber, and f and §* are the strain sensitivity and thermal sensitivity, respectively. Equation 5 shows that the Bragg wavelength A changes linearly with variations in the temperature (å 1) and axial strain of the Bragg grating (8, ), as confirmed by our previous studies [1, 13,14]. Obviously, the strain sensitivity f is a function of material properties and the strained state of the fiber.…”

supporting

confidence: 69%

“…Therefore, FBG sensors seem to be ideal for realizing fiber optic smart structures, where sensors are embedded in or attached to structures for a number of technical objectives, such as health monitoring, impact detection, shape control, and vibration damping, by means of the provision of realtime sensing information, such as strain, temperature, and vibration. FBG sensors have been used in bridges, highways, textiles, mines, marine vehicles, medical therapies, and aircraft [ 1, 10,11,13]. Because the physical size of optical fibers is extremely small compared with other strain measuring components, they can be embed-ded in structures to determine strain distribution without significantly inHuencing the mechanical properties of the host materials [ 14].…”

mentioning

confidence: 99%

Compression Force Measured by Fiber Optic Smart Cellular Textile Composites

Bin

Tao

et al. 2004

Textile Research Journal

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This paper is concerned with a study of compression force measured by smart cellular textile composites integrated with fiber Bragg grating (FBG) sensors. The novel design of the cellular textile composite structures integrated with FBG sensors is reported. Unit cells of a cylindrical composite shell are fabricated from glass and polyester woven fabrics and epoxy, and are used to measure compression loads. When the composite shell unit is under pressure, the axial strain induced in the FBG sensor can be determined by the Bragg wavelength shift obtained from an optic spectrum analysis. A theoretical analysis of the fiber's axial strain focuses on compression load. The influences of environmental temperature, thickness, and effective moduli of the composites, and position and direction of the FBG sensors are discussed. The sensitivity of this device is 0.42 nm/N (for the polyester composite) and 0.29 nm/N (for the glass composite), and the measurement range is 0-2.1 ' Also affiliated with Hong Kong Polytechnic University.

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“…As visible, the β values range from 0.32 cm·nm −1 to 2.78 cm·nm −1 . Such a dispersion might be attributable to two causes: the sensor manufacturing process (in fact, as demonstrated by Tang et al in [ 36 ], the sensitivity of FBG-based sensors strictly depends on the housing material shape and stiffness) and the intra and inter subject variability of the sensor positioning (i.e., change in position of the sensor caused by the movements performed by a single volunteer during the trials execution, and the sensor different positioning between different subjects which is determined by the dissimilar anthropometric characteristics). In our experimental scenario, the wide variations in β values can be ascribable to the second cause, as the same sensor was exploited during the entire experimental protocol.…”

Section: Discussionmentioning

confidence: 99%

A Wearable Device Based on a Fiber Bragg Grating Sensor for Low Back Movements Monitoring

Zaltieri

Massaroni

Presti

et al. 2020

Sensors

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Low back pain (LBP) is one of the musculoskeletal disorders that most affects workers. Among others, one of the working categories which mainly experiences such disease are video terminal workers. As it causes exploitation of the National Health Service and absenteeism in workplaces, LBP constitutes a relevant socio-economic burden. In such a scenario, a prompt detection of wrong seating postures can be useful to prevent the occurrence of this disorder. To date, many tools capable of monitoring the spinal range of motions (ROMs) are marketed, but most of them are unusable in working environments due to their bulkiness, discomfort and invasiveness. In the last decades, fiber optic sensors have made their mark allowing the creation of light and compact wearable systems. In this study, a novel wearable device embedding a Fiber Bragg Grating sensor for the detection of lumbar flexion-extensions (F/E) in seated subjects is proposed. At first, the manufacturing process of the sensing element was shown together with its mechanical characterization, that shows linear response to strain with a high correlation coefficient (R2 > 0.99) and a sensitivity value (Sε) of 0.20 nm∙mε−1. Then, the capability of the wearable device in measuring F/E in the sagittal body plane was experimentally assessed on a small population of volunteers, using a Motion Capture system (MoCap) as gold standard showing good ability of the system to match the lumbar F/E trend in time. Additionally, the lumbar ROMs were evaluated in terms of intervertebral lumbar distances (Δ d L 3 − L 1 ) and angles, exhibiting moderate to good agreement with the MoCap outputs (the maximum Mean Absolute Error obtained is ~16% in detecting Δ d L 3 − L 1 ). The proposed wearable device is the first attempt for the development of FBG-based wearable systems for workers’ safety monitoring.

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Effectiveness and optimization of fiber Bragg grating sensor as embedded strain sensor

Cited by 21 publications

References 22 publications

Tangential Load Measurements by a Smart Textile Composite

Tangential Load Measurements by a Smart Textile Composite

Compression Force Measured by Fiber Optic Smart Cellular Textile Composites

A Wearable Device Based on a Fiber Bragg Grating Sensor for Low Back Movements Monitoring

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