Phase-sensitive Optical Time-Domain Reflectometer(φ-OTDR)technology facilitates the real-time detection of vibration events along fiber optic cables by analyzing changes in Rayleigh scattering signals.This technology...Phase-sensitive Optical Time-Domain Reflectometer(φ-OTDR)technology facilitates the real-time detection of vibration events along fiber optic cables by analyzing changes in Rayleigh scattering signals.This technology is widely used in applications such as intrusion monitoring and structural health assessments.Traditional signal processing methods,such as Support Vector Machines(SVM)and K-Nearest Neighbors(KNN),have limitations in feature extraction and classification in complex environments.Conversely,a single deep learning model often struggles with capturing long time-series dependencies and mitigating noise interference.In this study,we propose a deep learning model that integrates Convolutional Neural Network(CNN),Long Short-Term Memory Network(LSTM),and Transformer modules,leveraging φ-OTDR technology for distributed fiber vibration sensing event recognition.The hybrid model combines the CNN's capability to extract local features,the LSTM's ability to model temporal dynamics,and the Transformer's proficiency in capturing global dependencies.This integration significantly enhances the accuracy and robustness of event recognition.In experiments involving six types of vibration events,the model consistently achieved a validation accuracy of 0.92,and maintained a validation loss of approximately 0.2,surpassing other models,such as TAM+BiLSTM and CNN+CBAM.The results indicate that the CNN+LSTM+Transformer model is highly effective in handling vibration signal classification tasks in complex scenarios,offering a promising new direction for the application of fiber optic vibration sensing technology.展开更多
Presented here is long-range distributed vibration sensing based on internal-modulation optical frequency domain reflectometry(OFDR).In the proposed system with internal modulation,a silicon-based photonic-chip laser i...Presented here is long-range distributed vibration sensing based on internal-modulation optical frequency domain reflectometry(OFDR).In the proposed system with internal modulation,a silicon-based photonic-chip laser is used as the laser source,and by controlling the output voltage curve of an arbitrary waveform generator to induce temperature change in the external cavity of the laser,a 10-GHz optical frequency tuning range is achieved.The complexity of the proposed internal-modulation system is lower than that of the traditional external-modulation OFDR system that combines a narrow-linewidth laser with a single-sideband modulator to achieve wavelength tuning.Cross-correlation analysis is used as a sensing mechanism to evaluate the similarity between Rayleigh scatter signals and to achieve vibration event localization.Experimental comparison is made of the vibration sensing performance of the external-and internal-modulation systems,and for a vibration event generated at a distance of 100.95 km,they locate it with a sensing spatial resolution of 43.0 m and 16.8 m,respectively.The results indicates that the proposed distributed vibration sensing based on internal modulation has better sensing performance and lower complexity compared to the traditional external-modulation system.In addition,the proposed system is single-ended and involves no optical amplification,which makes it very suitable for ultra-long-range sensing.展开更多
Accurate detection of physiological vibrations is vital for monitoring health and enabling sensory feedback in bioelectronics.Current technologies often suffer from low signal-to-noise ratios(SNR),bulkiness,and the ne...Accurate detection of physiological vibrations is vital for monitoring health and enabling sensory feedback in bioelectronics.Current technologies often suffer from low signal-to-noise ratios(SNR),bulkiness,and the need for external amplification.Here,we introduce piezoelectric internal ion-gated organic electrochemical transistors(Piezo-IGTs),which efficiently convert mechanical vibrations into amplified electrical signals.These devices integrate laminated P(VDF-TrFE)microfiber films as the gate atop the transistor channel,generating voltage upon deformation to modulate mobile ions in the conducting polymer.Fabricated via sequential deposition and lamination,Piezo-IGTs achieve high fill factors and efficient on-site amplification,improving SNR over standalone piezoelectric films.They operate near 0 V gate voltage,enabling low-power performance.We validate their functionality in mechanomyography,speech recognition,and mechanocardiography using microscale Piezo-IGTs.This self-contained,flexible architecture demonstrates promise for integration into implantable and wearable systems,offering real-time,high-fidelity acquisition of bio-mechanical signals in nextgeneration health monitoring and neuroprosthetic applications.展开更多
Tactile sensing of subcutaneous organ vibrations provides a promising route toward human-machine interfaces and wear-able diagnostics,particularly for voice rehabilitation and silent-speech communication.Here,we prese...Tactile sensing of subcutaneous organ vibrations provides a promising route toward human-machine interfaces and wear-able diagnostics,particularly for voice rehabilitation and silent-speech communication.Here,we present a bioinspired piezoelectric vibration sensor that mimics the graded stiffness and stress-based transduction mechanism of otolithic cilia in the human vestibular system.The device consists of a trapezoidal cantilever array with tip inertial masses,fabricated through a hybrid stereolithography 3D printing and laser micromachining process for rapid prototyping without cleanroom facilities.Finite-element modeling and experimental measurements demonstrate a fundamental resonance near 1.2 kHz,a 5%flat-bandwidth of 350 Hz,and an in-band charge sensitivity of 3.17 pC/g.A wearable proof-of-concept test further verifies the sensor's ability to reproducibly distinguish phoneme-specific vibration patterns in both time and frequency domains.This work establishes a foundation for bioinspired tactile sensing front-ends in wearable voice interfaces and other intelligent diagnostic systems integrated with machine-learning algorithms.展开更多
High sensitivity of a distributed optical-fiber vibration sensing （DOVS） system based on the phase-sensitivity optical time domain reflectometry （Ф-OTDR） technology also brings in high nuisance alarm rates （NARs...High sensitivity of a distributed optical-fiber vibration sensing （DOVS） system based on the phase-sensitivity optical time domain reflectometry （Ф-OTDR） technology also brings in high nuisance alarm rates （NARs） in real applications. In this paper, feature extraction methods of wavelet decomposition （WD） and wavelet packet decomposition （WPD） are comparatively studied for three typical field testing signals, and an artificial neural network （ANN） is built for the event identification. The comparison results prove that the WPD performs a little better than the WD for the DOVS signal analysis and identification in oil pipeline safety monitoring. The identification rate can be improved up to 94.4%, and the nuisance alarm rate can be effectively controlled as low as 5.6% for the identification network with the wavelet packet energy distribution features.展开更多
A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal ...A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal intensity in the usually adopted time-division multiplexing （TDM） technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing （WDM） technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz - 1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.展开更多
Flexible high-frequency vibration sensors are highly desirable in various real-world applications such as structural health monitoring,environmental monitoring,and the internet of things.However,developing a facile an...Flexible high-frequency vibration sensors are highly desirable in various real-world applications such as structural health monitoring,environmental monitoring,and the internet of things.However,developing a facile and effective method to fabricate vibration sensors simultaneously featuring high vibration frequency response-ability and flexibility remains a grand challenge.Herein,we report a flexible ultrahigh-frequency triboelectric vibration sensor(UTVS)prepared by a layer-particle-layer structure.Owing to the flexibility of the materials(i.e.,polyethylene terephthalate membrane)and the ultrahigh-frequency vibration response-ability of internal microparticles,the flexible UTVS exhibits an enhanced working frequency range of 3–170 kHz,which is much broader than previously reported triboelectric vibration sensors.Moreover,the UTVS can work not only in a flat state but also in a bent state due to its flexibility and the unique layer-particle-layer structural design.The UTVS shows nanometer-level vibration response-ability,omnidirectional response,stability in the temperature range of 10–70°C,good frequency resolution of 0.01 kHz,and excellent performance in burst vibration detection(e.g.,pencil lead break events and impact events from falling steel balls).With a collection of compelling features,the device is successfully demonstrated in vibration monitoring of curved structures(e.g.,real-time water pipeline leak monitoring).Such a flexible ultrahigh-frequency triboelectric vibration sensor holds great potential in a wide range of practical applications,such as communication,health care,and infrastructure monitoring.展开更多
Fiber-optic sensors have been developed to monitor the structural vibration with advantages of high sensitivity,immunity to electromagnetic interference(EMI),flexibility,and capability to achieve multiplexed or distri...Fiber-optic sensors have been developed to monitor the structural vibration with advantages of high sensitivity,immunity to electromagnetic interference(EMI),flexibility,and capability to achieve multiplexed or distributed sensing.However,the current fiber-optic sensors require precisely polarized coherent lasers as the lighting sources,which are expensive in cost and suffer from the power supply issues while operating at outdoor environments.This work aims at solving these issues,through developing a fully self-powered,natural-light-enabled approach.To achieve that,a spring oscillator-based triboelectric nanogenerator(TENG),a polymer network liquid crystal(PNLC),and an optical fiber were integrated.The external vibration drove the PNLC to switch its transparency,allowing the varia-tion of the incident natural light in the optical fiber.Compared with the majority of conventional TENG-based active vibration sensors,the developed paradigm does not suffer from the EMI,without requirements of the signal preamplifica-tion which consumes additional energy.The vibration displacement monitoring was performed to validate the sensing effectiveness of the developed paradigm.展开更多
Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D fl...Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D flexible coaxial piezoelectric fiber was directly fabricated by melt extrusion molding,whose core and sheath layer are respectively slender steel wire(i.e.,electrode)and PVDF(i.e.,piezoelectric layer).Moreover,such 1D flexible coaxial piezoelectric fiber possesses short response time and high sensitivity,which can be used as a selfpowered sensor for bending and vibration sensing.More interestingly,such 1D flexible coaxial piezoelectric fiber(1D-PFs)can be further endowed with 3D helical structure.Moreover,a wearable and washable motion monitoring system can be constructed via braiding such 3D helical piezoelectric fiber(3D-PF)into commercial textiles.This work paves a new way for developing 1D and 3D piezoelectric fibers through a one-step,continuous and environmentally friendly method,showing potential applications in the field of sensing and wearable electronics.展开更多
Driven by a wide range of real-world applications,significant efforts have recently been made to explore facile vibration measurement.Traditional vibration inspection systems are normally sensed via accelerometers,las...Driven by a wide range of real-world applications,significant efforts have recently been made to explore facile vibration measurement.Traditional vibration inspection systems are normally sensed via accelerometers,laser displacement sensors or velocimeters,and most of them are neither non-intrusive nor wide-spread.This paper presents a novel solution based on acoustic waves of commercial mobile phones to inspect mechanical vibration.The core observation is that the Doppler effect occurs when acoustic waves pass through a vibrating object.The study leverages this opportunity to build a bridge between the Doppler frequency excursion and the vibrating frequency of objects.The solution of difference operation of the reassignment vector is used to make time-frequency domain images more readable.Finally,by processing time-frequency images,the system further accomplishes two reconstruction approaches to find out the energy concentration of acoustic signals respectively based on ridges and clustering.Simulation and real-life applications are employed to show the effectiveness and practicability of the proposed approaches.Our prototype system can inspect the vibration period with a relative error of 0.08%.Furthermore,this paper studies two practical cases in life to associate our measurement solution with the requirements of daily life.展开更多
At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on...At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on phase-sensitive coherentoptical time domain reflectometry(Ф-COTDR) with the practi-cal pattern recognition function. We use fast Fourier trans-form(FFT) to exact features from intrusion events and a multi-class classification algorithm derived from support vector ma-chine(SVM) to work as a pattern recognition technique. Fivedifferent types of events are classified by using a classifica-tion algorithm based on SVM through a three-dimensional fea-ture vector. Moreover, the identification results of the patternrecognition system show that an identification accurate rate of92.62% on average can be achieved.展开更多
A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally...A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines.The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines(optical phase conductor or optical power ground wire),which are helpful for monitoring the frequency response characteristics of the ice-induced galloping,evaluating the motion tendencies of these cables,and avoiding the risk of flashover during galloping.The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China(Beijing,China).Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency,which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents,and these features are essential for the safety operation in smart grids.展开更多
We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth ...We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.展开更多
This article presents a high-speed distributed vibration sensing based on Mach-Zehnder-OTDR （optical time-domain reflectometry）. Ultra-weak fiber Bragg gratings （UWFBG）, whose backward light intensity is 2-4 order...This article presents a high-speed distributed vibration sensing based on Mach-Zehnder-OTDR （optical time-domain reflectometry）. Ultra-weak fiber Bragg gratings （UWFBG）, whose backward light intensity is 2-4 orders of magnitude higher than that of Rayleigh scattering, are used as the reflection markers. A medium-coherence laser can substitute conventional narrow bandwidth source to achieve an excellent performance of distributed vibration sensing since our unbalanced interferometer matches the interval of UWFBGs. The 3 m of spatial resolution of coherent detection and multiple simultaneous vibration sources locating can be realized based on OTDR. The enhanced signal to noise ratio （SNR） enables fast detection of distributed vibration without averaging. The fastest vibration of 25 kHz and the slowest vibration of 10Hz can be detected with our system successfully, and the linearity is 0.9896 with a maximum deviation of 3.46nε.展开更多
The field of micro-and nano-mechanics has seen rapid advances driven by applications in sensing,microscopy,and precision instrumentation.Accurate,time-resolved characterization of mechanical dynamics is essential for ...The field of micro-and nano-mechanics has seen rapid advances driven by applications in sensing,microscopy,and precision instrumentation.Accurate,time-resolved characterization of mechanical dynamics is essential for understanding device behaviour and improving performance.However,conventional optical and electrical methods face trade-offs between sensitivity,linearity,and bandwidth,while frequencydomain approaches are limited in capturing transient dynamics.Here,we present a frequency comb-based time-domain tracking technique for directly observing the full-range dynamic motion of atomic force microscopy(AFM)micro-cantilevers.By leveraging electro-optic sampling between femtosecond optical pulses and ultraprecise photocurrent timing signals,our system enables real-time measurements across six orders of magnitude–from~30 pm thermal fluctuations to~20μm nonlinear oscillations.The technique reveals complex behaviours including mode coupling,hysteresis,bifurcation,and transient modulation,while maintaining calibration fidelity through thermomechanical noise.This approach bridges the longstanding gap between ultra-sensitive and wide-range motion tracking,offering a powerful tool for studying nonlinear dynamics in micro-and nano-scale mechanical systems.Looking ahead,the method lays the groundwork for advances in high-resolution force sensing,AFM probe optimization,and the broader exploration of dynamic behaviour in precision microsystems.展开更多
A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a pha...A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.展开更多
基金Supported by Key Laboratory of Space Active Optical-Electro Technology of Chinese Academy of Sciences(2021ZDKF4)。
文摘Phase-sensitive Optical Time-Domain Reflectometer(φ-OTDR)technology facilitates the real-time detection of vibration events along fiber optic cables by analyzing changes in Rayleigh scattering signals.This technology is widely used in applications such as intrusion monitoring and structural health assessments.Traditional signal processing methods,such as Support Vector Machines(SVM)and K-Nearest Neighbors(KNN),have limitations in feature extraction and classification in complex environments.Conversely,a single deep learning model often struggles with capturing long time-series dependencies and mitigating noise interference.In this study,we propose a deep learning model that integrates Convolutional Neural Network(CNN),Long Short-Term Memory Network(LSTM),and Transformer modules,leveraging φ-OTDR technology for distributed fiber vibration sensing event recognition.The hybrid model combines the CNN's capability to extract local features,the LSTM's ability to model temporal dynamics,and the Transformer's proficiency in capturing global dependencies.This integration significantly enhances the accuracy and robustness of event recognition.In experiments involving six types of vibration events,the model consistently achieved a validation accuracy of 0.92,and maintained a validation loss of approximately 0.2,surpassing other models,such as TAM+BiLSTM and CNN+CBAM.The results indicate that the CNN+LSTM+Transformer model is highly effective in handling vibration signal classification tasks in complex scenarios,offering a promising new direction for the application of fiber optic vibration sensing technology.
基金supported by the 34th Research Institute of CETC Funding(Grant No.K134002021S604)the New Technology Research University Cooperation Project of the 34th Research Institute of CETC(Grant No.2021-1200-05-001900).
文摘Presented here is long-range distributed vibration sensing based on internal-modulation optical frequency domain reflectometry(OFDR).In the proposed system with internal modulation,a silicon-based photonic-chip laser is used as the laser source,and by controlling the output voltage curve of an arbitrary waveform generator to induce temperature change in the external cavity of the laser,a 10-GHz optical frequency tuning range is achieved.The complexity of the proposed internal-modulation system is lower than that of the traditional external-modulation OFDR system that combines a narrow-linewidth laser with a single-sideband modulator to achieve wavelength tuning.Cross-correlation analysis is used as a sensing mechanism to evaluate the similarity between Rayleigh scatter signals and to achieve vibration event localization.Experimental comparison is made of the vibration sensing performance of the external-and internal-modulation systems,and for a vibration event generated at a distance of 100.95 km,they locate it with a sensing spatial resolution of 43.0 m and 16.8 m,respectively.The results indicates that the proposed distributed vibration sensing based on internal modulation has better sensing performance and lower complexity compared to the traditional external-modulation system.In addition,the proposed system is single-ended and involves no optical amplification,which makes it very suitable for ultra-long-range sensing.
基金supported by the project G0F9421N that has received funding within the framework of the Odysseus program from the Research Foundation–Flanders(FWO)the EIC pathfinder Challenges grant(UPSIDE,101070931)ERC starting grant(aTONE,101078225)。
文摘Accurate detection of physiological vibrations is vital for monitoring health and enabling sensory feedback in bioelectronics.Current technologies often suffer from low signal-to-noise ratios(SNR),bulkiness,and the need for external amplification.Here,we introduce piezoelectric internal ion-gated organic electrochemical transistors(Piezo-IGTs),which efficiently convert mechanical vibrations into amplified electrical signals.These devices integrate laminated P(VDF-TrFE)microfiber films as the gate atop the transistor channel,generating voltage upon deformation to modulate mobile ions in the conducting polymer.Fabricated via sequential deposition and lamination,Piezo-IGTs achieve high fill factors and efficient on-site amplification,improving SNR over standalone piezoelectric films.They operate near 0 V gate voltage,enabling low-power performance.We validate their functionality in mechanomyography,speech recognition,and mechanocardiography using microscale Piezo-IGTs.This self-contained,flexible architecture demonstrates promise for integration into implantable and wearable systems,offering real-time,high-fidelity acquisition of bio-mechanical signals in nextgeneration health monitoring and neuroprosthetic applications.
文摘Tactile sensing of subcutaneous organ vibrations provides a promising route toward human-machine interfaces and wear-able diagnostics,particularly for voice rehabilitation and silent-speech communication.Here,we present a bioinspired piezoelectric vibration sensor that mimics the graded stiffness and stress-based transduction mechanism of otolithic cilia in the human vestibular system.The device consists of a trapezoidal cantilever array with tip inertial masses,fabricated through a hybrid stereolithography 3D printing and laser micromachining process for rapid prototyping without cleanroom facilities.Finite-element modeling and experimental measurements demonstrate a fundamental resonance near 1.2 kHz,a 5%flat-bandwidth of 350 Hz,and an in-band charge sensitivity of 3.17 pC/g.A wearable proof-of-concept test further verifies the sensor's ability to reproducibly distinguish phoneme-specific vibration patterns in both time and frequency domains.This work establishes a foundation for bioinspired tactile sensing front-ends in wearable voice interfaces and other intelligent diagnostic systems integrated with machine-learning algorithms.
基金The authors gratefully acknowledge the supports provided for this research by Youth Foundation （Grant No. 61301275）, Major Instrument Special Program （Grant No. 41527805）, the Major Program （Grant No. 61290312） of the National Science Foundation of China （NSFC）, and the fund of State Grid Corporation of China： Research on distributed multi-parameter sensing and measurement control technology for electric power optical fiber communication networks （Grant No. 5455HT160014）. This work is also supported by Program for Changjiang Scholars and Innovative Research Team in University （PCSIRT, IRT1218） and the 111 Project （B14039）.
文摘High sensitivity of a distributed optical-fiber vibration sensing （DOVS） system based on the phase-sensitivity optical time domain reflectometry （Ф-OTDR） technology also brings in high nuisance alarm rates （NARs） in real applications. In this paper, feature extraction methods of wavelet decomposition （WD） and wavelet packet decomposition （WPD） are comparatively studied for three typical field testing signals, and an artificial neural network （ANN） is built for the event identification. The comparison results prove that the WPD performs a little better than the WD for the DOVS signal analysis and identification in oil pipeline safety monitoring. The identification rate can be improved up to 94.4%, and the nuisance alarm rate can be effectively controlled as low as 5.6% for the identification network with the wavelet packet energy distribution features.
基金This work is supported by the Major Program of the National Natural Science Foundation of China （Grant No. 61290311）.
文摘A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal intensity in the usually adopted time-division multiplexing （TDM） technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing （WDM） technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz - 1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.
基金J.Y.acknowledges support from the National Natural Science Foundation of China(No.51675069)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJ1703047)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.2018CDQYGD0020 and cqu2018CDHB1A05)the Natural Science Foundation Projects of Chongqing(Nos.cstc2017shmsA40018 and cstc2018jcyjAX0076)Z.W.L.would like to thank the China Scholarship Council(No.201806050157)for its financial support.
文摘Flexible high-frequency vibration sensors are highly desirable in various real-world applications such as structural health monitoring,environmental monitoring,and the internet of things.However,developing a facile and effective method to fabricate vibration sensors simultaneously featuring high vibration frequency response-ability and flexibility remains a grand challenge.Herein,we report a flexible ultrahigh-frequency triboelectric vibration sensor(UTVS)prepared by a layer-particle-layer structure.Owing to the flexibility of the materials(i.e.,polyethylene terephthalate membrane)and the ultrahigh-frequency vibration response-ability of internal microparticles,the flexible UTVS exhibits an enhanced working frequency range of 3–170 kHz,which is much broader than previously reported triboelectric vibration sensors.Moreover,the UTVS can work not only in a flat state but also in a bent state due to its flexibility and the unique layer-particle-layer structural design.The UTVS shows nanometer-level vibration response-ability,omnidirectional response,stability in the temperature range of 10–70°C,good frequency resolution of 0.01 kHz,and excellent performance in burst vibration detection(e.g.,pencil lead break events and impact events from falling steel balls).With a collection of compelling features,the device is successfully demonstrated in vibration monitoring of curved structures(e.g.,real-time water pipeline leak monitoring).Such a flexible ultrahigh-frequency triboelectric vibration sensor holds great potential in a wide range of practical applications,such as communication,health care,and infrastructure monitoring.
基金This work was funded by HKSAR the Research Grants Council Early Career Scheme(Grant no.24206919)HKSAR Innovation and Technology Fund(Grant no.ITS/085/18)TencentUniversityRelationsProgramme(contract no.T-576-INV-20200507-01).
文摘Fiber-optic sensors have been developed to monitor the structural vibration with advantages of high sensitivity,immunity to electromagnetic interference(EMI),flexibility,and capability to achieve multiplexed or distributed sensing.However,the current fiber-optic sensors require precisely polarized coherent lasers as the lighting sources,which are expensive in cost and suffer from the power supply issues while operating at outdoor environments.This work aims at solving these issues,through developing a fully self-powered,natural-light-enabled approach.To achieve that,a spring oscillator-based triboelectric nanogenerator(TENG),a polymer network liquid crystal(PNLC),and an optical fiber were integrated.The external vibration drove the PNLC to switch its transparency,allowing the varia-tion of the incident natural light in the optical fiber.Compared with the majority of conventional TENG-based active vibration sensors,the developed paradigm does not suffer from the EMI,without requirements of the signal preamplifica-tion which consumes additional energy.The vibration displacement monitoring was performed to validate the sensing effectiveness of the developed paradigm.
基金the National Natural Science Foundation of China(No.51873199)Program for Innovative Research Team(in Science and Technology)in University(No.20IRTSTHN002)。
文摘Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D flexible coaxial piezoelectric fiber was directly fabricated by melt extrusion molding,whose core and sheath layer are respectively slender steel wire(i.e.,electrode)and PVDF(i.e.,piezoelectric layer).Moreover,such 1D flexible coaxial piezoelectric fiber possesses short response time and high sensitivity,which can be used as a selfpowered sensor for bending and vibration sensing.More interestingly,such 1D flexible coaxial piezoelectric fiber(1D-PFs)can be further endowed with 3D helical structure.Moreover,a wearable and washable motion monitoring system can be constructed via braiding such 3D helical piezoelectric fiber(3D-PF)into commercial textiles.This work paves a new way for developing 1D and 3D piezoelectric fibers through a one-step,continuous and environmentally friendly method,showing potential applications in the field of sensing and wearable electronics.
基金National Natural Science Foundation of China(Nos.61672151 and 61972081)DHU Distinguished Young Professor Program,China。
文摘Driven by a wide range of real-world applications,significant efforts have recently been made to explore facile vibration measurement.Traditional vibration inspection systems are normally sensed via accelerometers,laser displacement sensors or velocimeters,and most of them are neither non-intrusive nor wide-spread.This paper presents a novel solution based on acoustic waves of commercial mobile phones to inspect mechanical vibration.The core observation is that the Doppler effect occurs when acoustic waves pass through a vibrating object.The study leverages this opportunity to build a bridge between the Doppler frequency excursion and the vibrating frequency of objects.The solution of difference operation of the reassignment vector is used to make time-frequency domain images more readable.Finally,by processing time-frequency images,the system further accomplishes two reconstruction approaches to find out the energy concentration of acoustic signals respectively based on ridges and clustering.Simulation and real-life applications are employed to show the effectiveness and practicability of the proposed approaches.Our prototype system can inspect the vibration period with a relative error of 0.08%.Furthermore,this paper studies two practical cases in life to associate our measurement solution with the requirements of daily life.
文摘At present, the demand for perimeter security system is in-creasing greatly, especially for such system based on distribut-ed optical fiber sensing. This paper proposes a perimeter se-curity monitoring system based on phase-sensitive coherentoptical time domain reflectometry(Ф-COTDR) with the practi-cal pattern recognition function. We use fast Fourier trans-form(FFT) to exact features from intrusion events and a multi-class classification algorithm derived from support vector ma-chine(SVM) to work as a pattern recognition technique. Fivedifferent types of events are classified by using a classifica-tion algorithm based on SVM through a three-dimensional fea-ture vector. Moreover, the identification results of the patternrecognition system show that an identification accurate rate of92.62% on average can be achieved.
基金supported by the National Natural Science Foundation of China(Grant Nos.61775173,61975157,and 52071245)the Science and Technology Project of State Grid Corporation of China(Research on the basic technology of the next generation intelligent optical cable based on grating array fiber sensor,Grant No.5442XX190009).
文摘A distributed online fiber sensing system based on the phase-sensitive optical time domain reflectometer(Φ-OTDR)enhanced by the drawing tower fiber Bragg grating(FBG)array is presented and investigated experimentally for monitoring the galloping of overhead transmission lines.The chirped FBG array enhanced Φ-OTDR sensing system can be used to measure the galloping behavior of the overhead transmission lines(optical phase conductor or optical power ground wire),which are helpful for monitoring the frequency response characteristics of the ice-induced galloping,evaluating the motion tendencies of these cables,and avoiding the risk of flashover during galloping.The feasibility of the proposed online monitoring system is demonstrated through a series of experiments at the Special Optical Fiber Cable Laboratory of State Grid Corporation of China(Beijing,China).Results show that the proposed system is effective and reliable for the monitoring of galloping shape and characteristic frequency,which can predict the trend of destructive vibration behavior and avoid the occurrence of cable breaking and tower toppling accidents,and these features are essential for the safety operation in smart grids.
文摘We have demonstrated a distributed vibration sensor based on phase-sensitive optical time-domain reflectometer (φ-OTDR) system exhibiting immunity to the laser phase noise. Two laser sources with different linewidth and phase noise levels are used in the φ-OTDR system, respectively. Based on the phase noise power spectrum density of both lasers, the laser phase is almost unchanged during an extremely short period of time, hence, the impact of phase noise can be suppressed effectively through phase difference between the Rayleigh scattered light from two adjacent sections of the fiber which define the gauge length. Based on the phase difference method, the external vibration can be located accurately at 41.01 km by the(φ-OTDR system incorporating these two lasers. Meanwhile, the average signal-to-noise ratio (SNR) of the retrieved vibration signal by using Laser I is found to be -37.7 dB, which is comparable to that of -37.5 dB by using Laser II although the linewidth and the phase noise level of the two lasers are distinct. The obtained results indicate that the phase difference method can enhance the performance of(φ-OTDR system with laser phase-noise immunity for distributed vibration sensing, showing potential application in oil-gas pipeline monitoring, perimeter security, and other fields.
基金This work was supported in part by the National Natural Science Foundation of China （Gram No. 61735031）, Natural Science Foundation of Hubei Province of China （Grant No. 2018CFA056）, and the Excellent Dissertation Cultivation Funds of Wuhan University of Technology （Grant No. 2017-YS-057）.
文摘This article presents a high-speed distributed vibration sensing based on Mach-Zehnder-OTDR （optical time-domain reflectometry）. Ultra-weak fiber Bragg gratings （UWFBG）, whose backward light intensity is 2-4 orders of magnitude higher than that of Rayleigh scattering, are used as the reflection markers. A medium-coherence laser can substitute conventional narrow bandwidth source to achieve an excellent performance of distributed vibration sensing since our unbalanced interferometer matches the interval of UWFBGs. The 3 m of spatial resolution of coherent detection and multiple simultaneous vibration sources locating can be realized based on OTDR. The enhanced signal to noise ratio （SNR） enables fast detection of distributed vibration without averaging. The fastest vibration of 25 kHz and the slowest vibration of 10Hz can be detected with our system successfully, and the linearity is 0.9896 with a maximum deviation of 3.46nε.
基金supported by the National Research Foundation(NRF)of Korea(Grants RS-2024–00334727,RS-2024–00436737,RS-2021-NR060086)J.S.acknowledges the support from the National Research Foundation(NRF)of Korea(Grants 2022M3H3A1064154,RS-2023–00207732).
文摘The field of micro-and nano-mechanics has seen rapid advances driven by applications in sensing,microscopy,and precision instrumentation.Accurate,time-resolved characterization of mechanical dynamics is essential for understanding device behaviour and improving performance.However,conventional optical and electrical methods face trade-offs between sensitivity,linearity,and bandwidth,while frequencydomain approaches are limited in capturing transient dynamics.Here,we present a frequency comb-based time-domain tracking technique for directly observing the full-range dynamic motion of atomic force microscopy(AFM)micro-cantilevers.By leveraging electro-optic sampling between femtosecond optical pulses and ultraprecise photocurrent timing signals,our system enables real-time measurements across six orders of magnitude–from~30 pm thermal fluctuations to~20μm nonlinear oscillations.The technique reveals complex behaviours including mode coupling,hysteresis,bifurcation,and transient modulation,while maintaining calibration fidelity through thermomechanical noise.This approach bridges the longstanding gap between ultra-sensitive and wide-range motion tracking,offering a powerful tool for studying nonlinear dynamics in micro-and nano-scale mechanical systems.Looking ahead,the method lays the groundwork for advances in high-resolution force sensing,AFM probe optimization,and the broader exploration of dynamic behaviour in precision microsystems.
基金Acknowledgment This work was partly supported by the Major Program of the National Natural Science Foundation of China （Grant No. 61290311）, the Fundamental Research Funds for the Central Universities （Grant No. 2015Ⅲ056）, and Key Consulting Project of Chinese Academy of Engineering （Grant No. 2016-XZ-13）.
文摘A distributed fiber optic interferometric geophone array based on draw tower grating （DTG） array is proposed. The DTG geophone array is made by the DTG array fabricated based on a near-contact exposure through a phase mask during the fiber drawing process. A distributed sensing system with 96 identical DTGs in an equal separation of 20 m and an unbalanced Michelson interferometer for vibration measurement has been experimentally validated compared with a moving-coil geophone. The experimental results indicate that the sensing system can linearly demodulate the phase shift. Compared with the moving coil geophone, the fiber optic sensing system based on DTG has higher signal-to-noise ratio at low frequency.
