- 标题
- 摘要
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- 实验方案
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Vibration Monitoring Based on Flexible Multi-walled Carbon Nanotube / Polydimethylsiloxane Film Sensor and the Application on Motion Signal Acquisition
摘要： Flexible sensors at small scales have potential applications in many fields. Until now, the research on high-performance vibration sensors based on soft materials with high sensitivity and precision, fast response, high stability are still in its infancy. In this work, a flexible, wearable and high precision film sensor based on multi-walled carbon nanotube (MWCNT) was prepared via a vacuum filtration process and then encapsulated within polydimethylsiloxane (PDMS). The sensor exhibits an ultrahigh sensitivity with gauge factor of 214.3 at flexural strain of 0.4 %. When used to monitor the vibration responses of a carbon-fiber beam induced by the base excitation and impact hammer, the time and frequency responses were comparable with the results obtained by the accelerometer, with difference less than 1 %. In addition, when the MWCNT/PDMS thin film was employed as an electronic skin sensor attached on the human body to detect human activities, the high sensitivity and repeatability demonstrate a great potential application in monitoring human motion.
关键词： human motion monitoring,vibration sensing,multi-walled carbon nanotube,film sensor
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || Performance Optimization of Self-exited Piezoelectric Vibration Sensor
摘要： Performance evaluation of self-exited piezoelectric vibration sensor with respect to dimensions, shape and material are carried out in the present paper, with an objective to ?nd the design and dimension for which we get optimum performance in terms of frequency response and sensitivity. A new design is proposed based on the parameters discussed, for design COMSOL tool is used. Response for the designed vibration sensor for variation in frequency, with varying dimensions is performed for both differential and lateral loads. Results obtained give us information regarding the operating load, bandwidth, power, voltage and current ranges for best performance.
关键词： Piezoelectric,Optimization,Frequency response,Vibration
更新于2025-09-23 15:21:01
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Optical vibration modes in multi-layer quantum dots of polar ternary mixed crystals
摘要： Within the framework of the dielectric continuum approach and the modified random-element isodisplacement model, the optical vibration modes as well as the corresponding electron-phonon interactions in spherical multi-layer quantum dots (QDs) consisting of ternary mixed crystals (TMCs) are investigated in detail. The dispersion relation and electron-phonon interaction Hamiltonian are obtained. As applications of the present theory, the numerical calculations for the ZnS/ZnxCd1-xS/ZnS and GaAs/AlxGa1-xAs/GaAs QDs are performed and discussed. Considering the "one-mode" and "two-mode" behaviors of the TMCs, the results show that there are 5 and 7 branches of interface/surface optical (IO/SO) phonon modes in the two systems, respectively. It is found that the effects of TMCs have a remarkable influence on the optical phonon frequencies and the electron-phonon interactions. The results also reveal that the presence of the cap layer introduces significant influence on the TMCs effects of optical phonon in multi-layer QDs. We hope that our theoretical results can stimulate further investigations of related photoelectric properties, as well as device applications in multi-layer QDs consisting of TMCs.
关键词： ternary mixed crystal,electron-phonon interaction,optical vibration mode,multi-layer quantum dot
更新于2025-09-23 15:21:01
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The contribution to the modal analysis using an infrared camera
摘要： The paper deals with modal analysis using an infrared camera. The test objects were excited by the modal exciter with narrowband noise and the response was registered as a frame sequence by the high speed infrared camera FLIR SC7500. The resonant frequencies and the modal shapes were determined from the infrared spectrum recordings. Lock-in technology has also been used. The experimental results were compared with calculated natural frequencies and modal shapes.
关键词： resonance,infrared camera,modal analysis,vibration,modal shape
更新于2025-09-23 15:21:01
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Evaluation of Bone Conduction Vibration System Using Photoacoustic Effect
摘要： This article proposes a novel bone conduction vibrator based on an interesting phenomenon where audible sound can be perceived when a vibration is produced using a laser beam that is synchronized to the sound and this vibration is transmitted to an auricular cartilage. To study this phenomenon, we measured the effect using a rubber sheet with similar properties to those of soft tissue, together with an acceleration sensor, and found that audible sound was produced in the sample. We also calculated the force level based on the mechanical impedance and the acceleration in the proposed system. It is expected that a force level equal to the reference equivalent threshold force level can be achieved at a light intensity below the safety limit for human skin exposure by choosing an irradiation wavelength at which a larger degree of optical absorption occurs. This novel application of the photoacoustic effect is promising for bone conduction hearing aids.
关键词： bone conduction,hearing aids,laser,vibration,photoacoustic effect
更新于2025-09-23 15:21:01
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Terahertz Spectral of Enantiomers and Racemic Amino Acids by Time-Domain-Spectroscopy Technology
摘要： The absorption spectra of four amino acids were studied. These spectra are obtained by terahertz time-domain spectroscopy (TDS) technique. The four amino acids are alanine, methionine, leucine, and valine, respectively. The spectra of their enantiomers (L-, D-) and racemic compounds (DL-) were investigated. Although the two isomers have very similar structures, their absorption spectra are obviously different. The absorption coefficient of each structure is calculated by the density functional theory (DFT), and the simulated spectra of each structure are obtained. It is shown that the number of the calculated peaks is in good agreement with the experimental ones. The experimental spectra were compared with the theoretical spectra. The differences between the absorption spectra of isomers are presented, and the reasons for the differences were analyzed. The vibratory spectra of biomolecules were studied, and the correlation between molecular structure and function was further understood.
关键词： collective vibration,isomers,amino acids,density functional theory,terahertz time-domain spectroscopy
更新于2025-09-23 15:21:01
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A Flexible Mode Electrolytic Capacitor-Free LED Driver with High-Efficiency Over a Wide Range of Input Voltage
摘要： This paper demonstrates the use of low-cost off-the-shelf (OTS) microelectromechanical system (MEMS) technology to perform vibration-based in situ monitoring, diagnostics, and characterization of a MEMS microball bearing supported radial air turbine platform. A multimodal software suite for platform automation and sensor monitoring is demonstrated using a three-level heuristic software suite and sensor network. The vibration diagnostic methods used in the platform have applications in rotary microsystems for the early detection of failure, fault diagnosis, and integrated diagnostic systems for feedback-based optimization to increase device performance, reliability, and operational lifetimes. The studied rotary microdevice used a dual OTS accelerometer configuration for dual range parallel redundant vibration analysis. The sensor suite has been used to monitor and detect multiple operational parameters measured optimally in time or frequency domains such as rotor instability, imbalance, wobble, and system resonance. This paper will lay the framework for active diagnostics in future MEMS devices through integrated systems.
关键词： rotating machine stability,Non-destructive,vibration measurement,measurement,rotating machine
更新于2025-09-23 15:19:57
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Highly efficient flexible perovskite solar cells made via ultrasonic vibration assisted room temperature cold sintering
摘要： With emerging flexible substrates, perovskite solar cells have entered into a new stage of development toward flexibility, portability and miniaturization. However, this promising landscape is hindered by the necessity the high-temperature processes. In this study, a highly efficient, stable and flexible planar perovskite solar cell is fabricated using an all-room temperature pathway. First, a nanocrystalline SnO2 layer is deposited on polyethylene terephthalate/indium tin oxide via room-temperature sol-gel strategy. Then (FAPbI3)0.85(MAPbBr3)0.15 is coated thereon, by annealing-free solution deposition. In both steps films are subjected to ultrasonic vibration, right after deposition, while they are still wet. By virtue of the ultrasonic energy, surface evaporation of liquid molecules is accelerated, impurities are removed from deposited wet film, and as a result shrinkage and sintering occur at room temperature. The cell is completed by a classical method, showing a champion power conversion efficiency of 17.38%, based on 0.16 cm2 active area. After 480 h aging in 50% relative humidity, this cell retains 80% of its initial performance. This research promises efficient, inexpensive and sustainable systems for harvesting solar energy by wearable modules.
关键词： SnO2,Cold sintering,Ultrasonic vibration,Perovskite solar cells,Flexible
更新于2025-09-23 15:19:57
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Heterodyne interferometry at ultra-high frequencies with frequency-offset-locked semiconductor lasers
摘要： Modern broadband telecommunications require microelectromechanical filters which mechanically vibrate at ultra-high frequencies up to several gigahertz. Heterodyne interferometers, so-called laser-Doppler vibrometers (LDVs), provide a sensitive and contactless measurement technique for vibrations in such filters, but are limited in GHz heterodyning by the efficiency drop of acousto-optic frequency shifting. Heterodyning by frequency-offset locking of two lasers in an optoelectronic phase-locked loop (OPLL) overcomes this limitation. This is demonstrated with our LDV setup with heterodyning up to 1.4 GHz via offset locking of two semiconductor lasers at visible wavelength. The experiments show a vibration-amplitude resolution of less than 1 pm Hz for frequencies higher than 50 MHz up to 700 MHz. The bandwidth is only per limited by our photodetectors. This amplitude resolution already qualifies our LDV for vibration measurement of microelectromechanical filters at ultra-high frequencies. We present a comprehensive model for the vibration-amplitude resolution of a LDV with this technique including the laser linewidths, the OPLL transfer function, and interferometer delays. The experiments with our LDV validate the model predictions from numerical simulations. Finally, we discuss the collapse of the heterodyne carrier at vanishing mutual coherence due to interferometer delays, the transition to shot-noise-limited detection, and provide design recommendations.
关键词： MEMS testing,Vibration measurement,Optical phase-locked loop,Heterodyne interferometry
更新于2025-09-23 15:19:57
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Evaluating the Incident Energy of Arcs In Photovoltaic DC Systems: Comparison Between Calculated and Experimental Data
摘要： This paper demonstrates the use of low-cost off-the-shelf (OTS) microelectromechanical system (MEMS) technology to perform vibration-based in situ monitoring, diagnostics, and characterization of a MEMS microball bearing supported radial air turbine platform. A multimodal software suite for platform automation and sensor monitoring is demonstrated using a three-level heuristic software suite and sensor network. The vibration diagnostic methods used in the platform have applications in rotary microsystems for the early detection of failure, fault diagnosis, and integrated diagnostic systems for feedback-based optimization to increase device performance, reliability, and operational lifetimes. The studied rotary microdevice used a dual OTS accelerometer configuration for dual range parallel redundant vibration analysis. The sensor suite has been used to monitor and detect multiple operational parameters measured optimally in time or frequency domains such as rotor instability, imbalance, wobble, and system resonance. This paper will lay the framework for active diagnostics in future MEMS devices through integrated systems.
关键词： rotating machine stability,Non-destructive,vibration measurement,measurement,rotating machine
更新于2025-09-23 15:19:57