68 research outputs found
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[INVITED] Developments in optical fibre sensors for industrial applications
The development of intrinsic optical fiber pH sensors based on fluorescence from novel coumarin dyes which are covalently immobilized onto the distal end of the fiber is described. The sensors provide response in the pH range of 0.5 − 6 with good stability over 24 h. The response time of the sensors is approximately 25 s. The sensors show no sensitivity to ionic strength (IS) and have excellent photostability
Amplified spontaneous emission-based technique for simultaneous measurement of temperature and strain by combining active fiber with fiber gratings
This article reports on an optical fiber-based sensing system for carrying out the simultaneous measurement of temperature and strain. The sensor design is based on the combination of active dopedoptical fiber and fiber gratings. Erbium/ytterbium co-doped fiber is used to meet the requirements for both high temperature responsivity and small sensor size to address smart structure applications. The temperature dependence of the amplified spontaneous emission power under different pump wavelengths is used as the basis of the sensor and an optical reference to enhance the measurement resolution is discussed. The feasibility of this technique for simultaneous measurement of temperature and strain is demonstrated
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Fiber-Bragg-Grating-Based Sensor System to Measure Battery State of Charge Based on a Machine Learning Model
Real-time monitoring of the state of charge (SOC) of the batteries used in a wide variety of applications is becoming increasingly important, especially given the impetus by the current targets towards “net-zero”. In this research, an advanced approach was used involving fiber Bragg grating (FBG)-based sensors that were developed and implemented for the measurement of the key parameters required to ensure optimum battery performance. In this work, one of the biggest challenges to assess (and then map) the data from the sensor system developed is tackled in order to better understand the key parameters of the battery in an efficient and improved way. It is well known that the relationship between the changes in the resonance wavelength of the FBGs used in the sensor system, arising due to change in the electrical parameters of the battery, is complex and dependent on several different factors. In this work, this effect was evaluated by coupling the sensor data to a data-driven regression model approach that was developed for the measurement of the SOC of the batteries used, and this was obtained directly and conveniently from the FBG data. In this comprehensive study, FBG-based sensors were fabricated and then installed onto the battery, which then was subjected to a range of charging–discharging cycles, following which the electrical parameters of the battery were estimated from recorded data using a black-box machine learning (ML) model. Data-driven regression algorithms were employed for the training of the black-box model. The efficiency of the estimation of the SOC of the battery from the FBG-based sensor data was found to be high, at 99.62% (R2 values of Estimated SOC and True SOC line), creating a very satisfactory result for this key measurement. Thus, the work shows the robustness of the FBG-based sensor system combined with the neural network algorithm as an effective way to evaluate the electrical parameters of the battery, which is particularly important, as no physical/electrochemical/electrical model of the system is thus required
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Field tests of fibre Bragg grating sensors incorporated into CFRP for railway bridge strengthening condition monitoring
The EU is in the process of upgrading the national railway networks to meet the demands from high-speed passenger trains and heavy Freight traffic. This upgrade necessitates a review of the development and implementation of novel technologies to repair and strengthen the existing bridge structures and to improve their performance.
This paper presents the evaluation results of the use of FBG strains sensors incorporated in CFRP (carbon fibre reinforcement polymer) rods and tubes as part of the methodology for monitoring the performance of the NSMR (near surface mounted reinforcement) which is an essential part of the repair and strengthening of bridges. In addition, a new method has been tested for the first time using CFRP tubes which calls for the drilling of holes instead of sawing grooves in the installation process.
The paper discusses in some detail the strengthening mechanism, FBG sensor implementation and the electronic system used to interrogate the FBG sensors. The results obtained from the monitoring show that FBG sensors can be integrated into CFRP and that reliable measurements can be made. However, in this particular project, the strain loading is very moderate so consequently the strain levels are in the elastic regime
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3D-printed Tilt Sensor based on an embedded Two-mode Fiber Interferometer
A 3D-printed tilt fiber sensor using a two-mode fiber interferometer (TMFI) as the sensing mechanism has been demonstrated. The TMFI was constructed by splicing single-mode fibers (SMF28s) at both ends of a two-mode fiber (TMF) to generate a comb-like interference spectrum that is sensitive to bending. A 3D-printed cantilever with a weight attached to one end was used to induce bending as the structure was tilted and by embedding the TMFI onto the 3D printed cantilever, different tilt angles can be measured, as a result of the bending of the fiber. The TMFI exhibited a linear response towards the tilt angles, θ, with a responsivity of 1 × 10-2 nm/deg at negative θ (0 to -90°) and 5 × 10-3 nm/deg at positive θ (0 to 90°), respectively. The sensor was able to detect small angle changes in increments as small as 1° and it performs better than embedded FBG sensors. The tilt sensor proposed has a small form factor and simple design, as well as being cost-effective and light-weight, thus showing significant potential for a variety of civil engineering applications
ON BOARD EXHAUST EMISSION MONITORING OF ROAD VEHICLES - A HIGH TECH SOLUTION TO POLLUTION FROM TRAFFIC?
A pH optode based on thymol blue: application to determination of CO2 using flow injection analysis system
In situ cross-calibration of in-fibre Bragg Grating and Electrical Resistance Strain Gauges for structural monitoring using an extensometer
Optical fibre-based sensor technology for humidity and moisture measurement: Review of recent progress
Humidity and moisture sensing is becoming increasingly important in industry and through a wide spectrum of applications and a review of research activity in the field across a range of technologies was presented previously by some of the authors. Recognizing the major developments in the last few years, especially in the field of fibre optic humidity and moisture sensing, this paper aims to extend that approach to review and categorize recent progress in the optical fibre field for the measurement of humidity and moisture and examine, as a result, the breadth of applications that now are being discussed
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