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Article

Yongxing Guo, Min Chen, Li Xiong, Xinglin Zhou and Cong Li

The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the…

Abstract

Purpose

The purpose of this study is to present the state of the art for fiber Bragg grating (FBG) acceleration sensing technologies from two aspects: the principle of the measurement dimension and the principle of the sensing configuration. Some commercial sensors have also been introduced and future work in this field has also been discussed. This paper could provide an important reference for the research community.

Design/methodology/approach

This review is to present the state of the art for FBG acceleration sensing technologies from two aspects: the principle of the measurement dimension (one-dimension and multi-dimension) and the principle of the sensing configuration (beam type, radial vibration type, axial vibration type and other composite structures).

Findings

The current research on developing FBG acceleration sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of a new information detection method. This paper hypothesizes that in the future, the following research trends will be strengthened: common single-mode fiber grating of the low cost and high utilization rate; high sensitivity and strength special fiber grating; multi-core fiber grating for measuring single-parameter multi-dimensional information or multi-parameter information; demodulating equipment of low cost, small volume and high sampling frequency.

Originality/value

The principle of the measurement dimension and principle of the sensing configuration for FBG acceleration sensors have been introduced, which could provide an important reference for the research community.

Details

Sensor Review, vol. 41 no. 1
Type: Research Article
ISSN: 0260-2288

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Article

Vincent A. Handerek

Optical fibre multiplexed sensors are used to make measurements at multiple, discrete locations, usually by sending optical signals between each measurement location and a…

Abstract

Optical fibre multiplexed sensors are used to make measurements at multiple, discrete locations, usually by sending optical signals between each measurement location and a conveniently positioned optical interrogation instrument. It is rapidly becoming practical to construct multiplexed optical fibre sensor arrays based on in‐fibre Bragg gratings. A Bragg grating can be produced in an optical fibre by writing a periodic variation in the refractive index of the fibre’s core along the axis, using ultra‐violet light. Multiplexing applications will appear ranging from the small scale, with only a few sensors, up to very large scales with hundreds of sensors.

Details

Sensor Review, vol. 18 no. 1
Type: Research Article
ISSN: 0260-2288

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Article

Jiang Qi

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed…

Abstract

Purpose

The purpose of this paper is to compare the sensing characteristics of uniform fiber Bragg grating (FBG) and tilted fiber Bragg grating (TFBG) by presenting a detailed research review. Temperature, axial strain, bending, vibration and refractive index measurands of FBG and TFBG sensor are presented and some significant differences are found.

Design/methodology/approach

Theoretical analysis and practical application in engineering are investigated and compared from other authors' research papers and self analysis. Spectra behavior of both FBG and TFBG are discussed.

Findings

There are found to be significant differences in temperature, axial strain, bending, vibration and refractive index sensing characteristics of FBG and TFBG.

Originality/value

The paper's analysis is comprehensive and clear and provides readers with the sensing characteristics of FBG and TFBG in detail.

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Article

Stephen J. Mihailov, Dan Grobnic, Christopher W. Smelser, Robert B. Walker, Ping Lu and Huimin Ding

The purpose of this paper is to present a review of research performed at the Communications Research Centre Canada on sensing applications of femtosecond infrared…

Abstract

Purpose

The purpose of this paper is to present a review of research performed at the Communications Research Centre Canada on sensing applications of femtosecond infrared laser‐inscribed Bragg gratings.

Design/methodology/approach

By using fibre Bragg gratings induced with ultrafast infrared radiation, inscription of high temperature stable sensors in standard and exotic optical waveguides is investigated for a variety of novel applications.

Findings

Generally, femtosecond laser‐induced gratings are effective sensors that can be applied in situations and environments where most fibre optic sensors are not effective.

Originality/value

The paper is a review of existing work already published in the literature and provides an overview of this technology to the reader.

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Article

Wenlong Liu, Yongxing Guo, Li Xiong and Yi Kuang

The purpose of this paper is to present the latest sensing structure designs and principles of information detection of fiber Bragg grating (FBG) displacement sensors…

Abstract

Purpose

The purpose of this paper is to present the latest sensing structure designs and principles of information detection of fiber Bragg grating (FBG) displacement sensors. Research advance and the future work in this field have been described, with the background that displacement and deformation measurements are universal and crucial for structural health monitoring.

Design/methodology/approach

This paper analyzes and summarizes the existing FBG displacement sensing technologies from two aspects principle of information detection (wavelength detection, spectral bandwidth detection, light intensity detection, among others) and principle of the sensing elastomer structure design (cantilever beam type, spring type, elastic ring type and other composite structures).

Findings

The current research on developing FBG displacement sensors is mainly focused on the sensing method, the construction and design of the elastic structure and the design of new information detection method. The authors hypothesize that the following research trends will be strengthened in future: temperature compensation technology for FBG displacement sensors based on wavelength detection; a study of more diverse elastic structures; and fiber gratings manufactured with special fibers will greatly improve the performance of sensors.

Originality/value

The latest sensing structure designs and principles of information detection of FBG displacement sensors have been proposed, which could provide important reference for research group.

Details

Sensor Review, vol. 39 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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Article

Mahmoud M.A. Eid and Ahmed Nabih Zaki Rashed

The purpose of this study aims to simulate the long-period fiber grating sensor pulse peak position against the transmission range. The long-period fiber grating sensor…

Abstract

Purpose

The purpose of this study aims to simulate the long-period fiber grating sensor pulse peak position against the transmission range. The long-period fiber grating sensor pulse peak position against the transmission range is simulated clearly where the pulse peak value at zero position is 0.972655 with the ripple factor of unity. It is demonstrated that the long-period fiber grating sensor bandwidth can be estimated to be 50 µm. Wavelength shift of the long-period grating sensor (LPGS) is reported against grating wavelength, applied temperatures and applied micro strain.

Design/methodology/approach

This work has reported the numerical simulation of LPGS transmission spectrum behavior characteristics under the strain and temperature effects by using OptiGrating simulation software. The sensor fabrication material is silica-doped germanium. The transmittivity/reflectivity and input spectrum pulse intensity of long-period Bragg sensor variations are simulated against the grating wavelength variations. Input/output pulse intensity of LPGS variations is simulated against the timespan variations with the Gaussian input pulse from 100 to 500 km link length.

Findings

Temperature variation and strain variation of the LPGS are outlined against both applied temperatures and micro-strain variations at the central grating wavelength of 1,550 nm.

Originality/value

It is demonstrated that the long period fiber grating sensor bandwidth can be estimated to be 50 µm. Wavelength shift of the long period grating sensor is reported against both grating wavelength, applied temperatures and applied micro strain. Temperature variation and strain variation of the long period grating sensor are outlined against both applied temperatures and micro strain variations at the central grating wavelength of 1550 nm.

Details

Sensor Review, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0260-2288

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Article

Jinu Paul, Zhao Liping, Bryan Ngoi and Fang Zhong Ping

Polymeric coatings and packaging are often used to enhance the temperature sensitivity of fiber Bragg grating temperature sensors. The high thermal expansion coefficient…

Abstract

Polymeric coatings and packaging are often used to enhance the temperature sensitivity of fiber Bragg grating temperature sensors. The high thermal expansion coefficient of the polymer enhances the thermal sensitivity by improving the wavelength shift due to thermal expansion. The adhesion of the polymeric coatings to the silica based optical fiber plays an important role in the wavelength response characteristics of fiber Bragg gratings with respect to temperature. Experiments are done to qualitatively analyze the influence of adhesion. Three‐dimensional finite element simulations have been carried out. Spring elements are used to interconnect the nodes of the meshed models of optical fiber and coating. The effect of adhesion is studied as a function of spring stiffness.

Details

Sensor Review, vol. 24 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

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Article

Yongxing Guo, Jianjun Fu, Longqi Li and Li Xiong

Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its…

Abstract

Purpose

Centrifugal model tests can accelerate the characterization of landslides and demonstrate the form of slope failure, which is an important measure to research its instability mechanisms. Simply observing the slope landslide before and after a centrifugal model test cannot reveal the processes involved in real-time deformation. Electromagnetic sensors have severed as an existing method for real-time measurement, however, this approach has significant challenges, including poor signal quality, interference, and complex implementation and wiring schemes. This paper aims to overcome the shortcomings of the existing measurement methods.

Design/methodology/approach

This work uses the advantages of fiber Bragg grating (FBG) sensors with their small form-factor and potential for series multiplexing in a single fiber to demonstrate a monitoring strategy for model centrifugal tests. A slope surface deformation displacement sensor, FBG anchor sensor and FBG anti-slide piling sensor have been designed. These sensors are installed in the slope models, while centrifugal acceleration tests under 100 g are carried out.

Findings

FBG sensors obtain three types of deformation information, demonstrating the feasibility and validity of this measurement strategy.

Originality/value

The experimental results provide important details about instability mechanisms of a slope, which has great significance in research on slope model monitoring techniques and slope stability.

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Article

Yage Zhan, Kan Gu, Hua Wu and Jun Luo

The on‐line concentration and temperature measurement of solutions is of great interest as a means of quality production control in many industrial processes, such as in…

Abstract

Purpose

The on‐line concentration and temperature measurement of solutions is of great interest as a means of quality production control in many industrial processes, such as in food service industry, pharmaceuticals industry, chemical industry and environmental engineering, especially for harmful solutions or solutions that cannot be reached by the operator. This paper seeks to address these issues.

Design/methodology/approach

A high resolution all‐fiber multi‐parameter sensor system has been studied theoretically and experimentally. The sensor system can be used for on‐line monitoring of concentration and temperature simultaneously and dynamically. A combined long period fiber grating (CLPG) is used as the sensor head based on its resonance wavelength shifts being almost linearly with concentration and temperature, and also based on that the two applied resonance peaks have different concentration‐wavelength coefficients and different temperature‐wavelength coefficients. Two wavelength‐matched fiber Bragg gratings (FBGs) are used to convert resonance peak wavelengths of the CLPG into corresponding intensities for interrogation.

Findings

When the concentration and the temperature all fluctuate dynamically during experiments, a concentration resolution of 0.03 g/L has been achieved in the range of 0∼200 g/L, and a temperature resolution of 0.02C has been realized in the range of −20∼60C.

Originality/value

On‐line monitoring of concentration and temperature for solutions is a means of quality production control in biological, chemical and other many industrial processes, such as in food service industry, pharmaceuticals industry, chemical industry, and also in environmental engineering, especially for harmful solutions or solutions that cannot be reached by the operator. Optical fiber sensors have numerous advantages over traditional sensors, such as immunity to electromagnetic interference, higher stability and sensitivity, more easiness of multiplex, being competent for application in harsh environments, “smart structures” and on‐site measurements. Long period optical fiber grating sensor is the most appropriate sensor for multi‐parameter monitoring in the fields mentioned above, which has all the advantages of optical fiber sensor. Besides, optical fiber grating sensors can be used for monitoring more accurately because its signal is coded by wavelength. The all‐fiber sensor system is suitable for remote monitoring of many solutions, such as the solutions of NaCl, glucose, alcohol, and hydrocarbon.

Details

Sensor Review, vol. 33 no. 3
Type: Research Article
ISSN: 0260-2288

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Article

Robert Bogue

This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring.

Abstract

Purpose

This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring.

Design/methodology/approach

The system is described and field trials on both conventional and novel composite bridges are discussed. A FBG sensor‐based structural monitoring system was developed, based on a fluorescent fibre as the optical source. It used a tuneable, fibre‐coupled, Fabry‐Perot filter, actuated by piezoelectric transducers and operated over the bandwidth of the source at up to 250 scans/second. Light from the source was filtered and reflected back from the Bragg gratings, through optical couplers, to eight photodiode detectors. These detected the resulting time‐domain spectra of the sensors in each of the serially connected sensor arrays. The system was tested at City University and then subjected to trials on the Mjosund road bridge in Norway and on West Mill bridge in Oxfordshire, UK, which is the first bridge to be fabricated from a new type of composite material.

Findings

During the Norwegian trials the system was arranged with four or five FBG sensors per channel giving a total of 32 measurement points with eight parallel channels. Twelve conventional foil strain gauges and a number of thermocouples were also installed. Different static and dynamic loads were applied over a period of 18 months and the results showed that the thermally compensated strain data obtained optically matched those from the resistive gauges to within <5 με. During the construction stage of the Oxfordshire bridge, sections of the decking and longitudinal composite support beams were instrumented with 40 FBG sensors with temperature compensation, placed at pre‐selected sites of maximum strain. These exhibited a resolution of ±5 με and an operating range of over ±2,000 με.

Originality/value

This research has shown that multiplexed, multi‐point FBG sensor systems can accurately and reliably monitor both static and dynamic strains in large structures over a range of temperatures and for extended periods of time.

Details

Sensor Review, vol. 25 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

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