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[Lecture Notes in Electrical Engineering] Sensors and Microsystems Volume 629 (Proceedings of the 20th AISEM 2019 National Conference) || Relative Humidity Sensor Based on Tip of Multimode Optical Fiber Integrated with Photonic Crystal of Hydrogel Coated Polystyrene Nanoparticles
摘要： A relative humidity (RH) sensing device based on photonic crystal colloids auto-assembled directly on the tip of a multi-mode optical fiber is here described. The core-shell nanospheres are obtained by Polystyrene (PS) nanoporous structures (core) incorporated into a poly(N-isopropylacrylamide) (PNIPAM) hydrogel (shell) and are subsequently deposited via a vertical dip-coating technique on a multimode optical fiber tip. The sensing capability is due to the hydrogel shell that swells depending on the relative humidity that induce wavelength shift and amplitude changes in the photonic bandgap peak. Spectral characterization and sensing analysis are performed, and the obtained results show that spectral characteristics are highly non-linear and strongly manufacturing dependent. A resolution of 1% RH is measured at 30% RH that significantly decreases at higher RH. Hereby, numerical simulations based on the finite element method (FEM) have been performed in order to investigate the sensing mechanism.
关键词： Structural health monitoring,Deflection monitoring,Optical fiber sensors,Strain measurement
更新于2025-09-23 15:19:57
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A Method of Interstory Drift Monitoring Using a Smartphone and a Laser Device
摘要： Interstory drift is an important engineering parameter in building design and building structural health monitoring. However, many problems exist in current interstory drift monitoring methods. The traditional method is imprecise—double numerical integration of acceleration data—and other direct monitoring methods need professional equipment. This paper proposes a method to solve these problems by monitoring the interstory drift with a smartphone and a laser device. In this method, a laser device is installed on the ceiling while a smartphone is ?xed on a steel projection plate on the ?oor. Compared with a reference sensor, the method designed in this study shows that a smartphone is competent in monitoring the interstory drift. This method utilizes a smartphone application (APP) named D-Viewer to implement monitoring and data storage just in one place, which is also inexpensive. The results showed that this method has an average percent error of 3.37%, with a standard deviation of 2.67%. With the popularization of the smartphone, this method is promising in acquiring large amounts of data, which will be signi?cant for building assessment after an earthquake.
关键词： structural health monitoring,laser device,interstory drift,smartphone,seismic monitoring
更新于2025-09-23 15:19:57
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Optimal Design Methodology of Tapered Waveguide Transducers for Thickness Monitoring
摘要： For the purpose of providing transducers for long-term monitoring of wall thinning of critical pressure equipment in corrosion or high temperature environments, the optimal design methodology for tapered waveguide units was proposed in the present study. Firstly, the feasibility of the quasi-fundamental shear horizontal (SH0*) wave propagating in the tapered waveguide units was analyzed via numerical simulations, and the transmitting limitations of the non-dispersive SH0* wave were researched. Secondly, several tapered waveguide transducers with varying cross-sections to transmit pure SH0* wave were designed according to the numerical results. Experimental investigations were carried out, and the results were compared with waveguide transducers with a prismatic cross-section. It was found that the tapered waveguide units can transmit non-dispersive shear horizontal waves and suppress the wave attenuation at the same time. The experimental results agreed very well with the numerical simulations. Finally, high-temperature experiments were carried out, and the reliability of thickness measuring by the tapered waveguide transducers was validated. The errors between the measured and the true thicknesses were small. This work paves a solid foundation for the optimal design of tapered waveguide transducers for thickness monitoring of equipment in harsh environments.
关键词： optimal design,quasi-fundamental shear horizontal wave,structural health monitoring,tapered waveguide unit,harsh environment
更新于2025-09-23 15:19:57
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Investigation of a Bragg Grating-Based Fabrya??Perot Structure Inscribed Using Femtosecond Laser Micromachining in an Adiabatic Fiber Taper
摘要： This paper presents the fabrication of a fiber Bragg grating (FBG)-based Fabry–Perot (FP) structure (7 mm total length) in an adiabatic fiber taper, investigates its strain and temperature characteristics, and compares the sensing characteristics with a standard polyimide coated FBG sensor. Firstly, a simulation of the said structure is presented, followed by the fabrication of an adiabatic fiber taper having the outer diameter reduced to 70 μm (core diameter to 4.7 μm). Next, the sensing structure, composed of two identical uniform FBG spaced apart by a small gap, is directly inscribed point-by-point using infrared femtosecond laser (fs-laser) micromachining. Lastly, the strain and temperature behavior for a range up to 3400 με and 225 ?C, respectively, are investigated for the fabricated sensor and the FBG, and compared. The fabricated sensor attains a higher strain sensitivity (2.32 pm/με) than the FBG (0.73 pm/με), while both the sensors experience similar sensitivity to temperature (8.85 pm/?C). The potential applications of such sensors include continuous health monitoring where precise strain detection is required.
关键词： Fabry–Perot,microfiber sensor structure,direct writing,sensor for structural health monitoring,point-by-point fabrication,femtosecond laser micromachining,harsh environment fiber sensor
更新于2025-09-23 15:19:57
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Monitoring of type IV composite pressure vessels with multilayer fully integrated optical fiber based distributed strain sensing
摘要： We present the results of distributed fiber optic strain sensing for condition monitoring of a hybrid type IV composite fully wrapped pressure vessel using multilayer integrated optical fibers. Distributed strain sensing was performed for a total number of 252,000 load cycles until burst of the vessel. During this ageing test material fatigue could be monitored and spatially localized. Critical material changes were detected 17,000 cycles before material failure. Results have been validated by acoustic emission analysis.
关键词： Hybrid composite pressure vessel,Acoustic emission analysis,Structural health monitoring,Distributed fiber optic sensing
更新于2025-09-23 15:19:57
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A Novel Fabry-P??rot Optical Sensor for Guided Wave Signal Acquisition
摘要： In this paper, a novel hybrid damage detection system is proposed, which utilizes piezoelectric actuators for guided wave excitation and a new ?bre optic (FO) sensor based on Fabry-Perot (FP) and Fiber Bragg Grating (FBG). By replacing the FBG sensors with FBG-based FP sensors in the hybrid damage detection system, a higher strain resolution is achieved, which results in higher damage sensitivity and higher reliability in diagnosis. To develop the novel sensor, optimum parameters such as re?ectivity, a wavelength spectrum, and a sensor length were chosen carefully through an analytical model of the sensor, which has been validated with experiments. The sensitivity of the new FBG-based FP sensors was compared to FBG sensors to emphasize the superiority of the new sensors in measuring micro-strains. Lastly, the new FBG-based FP sensor was utilized for recording guided waves in a hybrid setup and compared to the conventional FBG hybrid sensor network to demonstrate their improved performance for a structural health monitoring (SHM) application.
关键词： ?ber optic sensors,guided waves,structural,health monitoring,hybrid PZT-FBG,Fabry-Perot
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Cleveland, OH, USA (2018.10.17-2018.10.19)] 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Block-Sparse Compressive Sensing for High-Fidelity Recording of Photoplethysmogram
摘要： This paper presents a novel compressive sensing (CS) framework for photoplethysmogram (PPG) recording. Exploiting the concept of block sparsity in CS, the proposed framework trains a block-sparsifying dictionary for the PPG signal using the block K-SVD (BK-SVD) algorithm. Next, the block sparse Bayesian learning (BSBL) algorithm is employed to utilize the block-sparsity information and recover the PPG signal from its compressively sampled counterpart. Using different PPG datasets prerecorded from the fingertip of a healthy human volunteer under normal and post-exercise conditions, our results demonstrate that the proposed CS framework based on BK-SVD + BSBL can achieve signal-to-noise and distortion ratio (SNDR) values of >10dB for compression ratios as high as 10, outperforming the previous approaches for compressive sensing of PPG that do not utilize the block-sparsity information.
关键词： photoplethysmogram,wearable health monitoring,Block sparsity,dictionary training,compressive sensing
更新于2025-09-19 17:15:36
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Dynamic and quasi-static signal separation method for bridges under moving loads based on long-gauge FBG strain monitoring
摘要： Structural health monitoring is an important means of obtaining the state information of bridges, and the extracted quasi-static strain signal can reflect the stress state of bridges directly. However, the strain signals acquired during the operation stage of bridges are dynamic, and the strain gauges used in the health monitoring system are short (no more than 10 cm), which means they are easily affected by small damage at the installation parts of bridges and thereby the monitoring signal abnormalities occur. A type of externally affixed long-gauge fiber strain gauge is used to monitor the health of bridges, and the dynamic and quasi-static signal separation method for long-gauge strain sensors is studied under different vehicle loads; at the same time, the dynamic monitoring performance of the long-gauge sensor is investigated in this paper. The quasi-static strain signal extracted from the dynamic macro-strain signal can be used to directly monitor the stress status of the bridge. The results show that the method proposed in this paper is feasible for extracting the quasi-static macro-strain from a dynamic long-gauge strain signal.
关键词： signal processing,bridge engineering,empirical mode decomposition method,macro-strain,Bridge health monitoring
更新于2025-09-19 17:15:36
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Crack monitoring in reinforced concrete beams by distributed optical fiber sensors
摘要： This paper investigates the use of distributed optical fiber sensors (DOFS) based on Optical Frequency Domain Reflectometry of Rayleigh backscattering for Structural Health Monitoring purposes in civil engineering structures. More specifically, the results of a series of laboratory experiments aimed at assessing the suitability and accuracy of DOFS for crack monitoring in reinforced concrete members subjected to external loading are reported. The experiments consisted on three-point bending tests of concrete beams, where a polyamide-coated optical fiber sensor was bonded directly onto the surface of an unaltered reinforcement bar and protected by a layer of silicone. The strain measurements obtained by the DOFS system exhibited an accuracy equivalent to that provided by traditional electrical foil gauges. Moreover, the analysis of the high spatial resolution strain profiles provided by the DOFS enabled the effective detection of crack formation. Furthermore, the comparison of the reinforcement strain profiles with measurements from a digital image correlation system revealed that determining the location of cracks and tracking the evolution of the crack width over time were both feasible, with most errors being below ±3 cm and ±20 mm, for the crack location and crack width, respectively.
关键词： crack monitoring,structural health monitoring,damage assessment,reinforced concrete,Concrete beams,distributed optical fiber sensors
更新于2025-09-19 17:13:59
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PHOTOVOLTAIC DRIVEN RESONANT WIRELESS ENERGY TRANSFER SYSTEM FOR IMPLANTABLE ELECTRONIC SENSOR
摘要： In order to energize the biomedical implantable electronic devices wirelessly for in vivo health monitoring of patients in an isolated, outdoor and inaccessible environment, an alternate driving energy source is highly desirable. In pertinent to this, a photovoltaic driven wireless energizing system has been explored. The system is designed to convert solar energy to a high frequency energy source so as to facilitate energy transfer through resonant inductive link to the automated bio-medical sensing system allied with the receiver unit. The received power is observed to be 286 mW for the coil separation gap of 5 cm and load value of 40 Ω at the resonant frequency of 772.3 kHz. The automated biomedical smart sensor is competent to acquire the body parameter and transmit the consequent telemetry data from the body to the data recording segment. The real-time body temperature parameter of di?erent living beings has been experimented, and to ensure the accuracy of the developed system, the observed parameter has been matched with a calibrated system. The proposed scheme can be suitable for monitoring wirelessly other in vivo health parameters such as blood pressure, bladder pressure, and physiological signals of the patients.
关键词： resonant wireless energy transfer,health monitoring,biomedical,photovoltaic,implantable electronic sensor
更新于2025-09-19 17:13:59