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laser doppler vibrometer

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https://www.readbyqxmd.com/read/29443068/design-and-characterization-methodology-for-efficient-wide-range-tunable-mems-filters
#1
Hasan Goktas
Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques to create an application-based microelectromechanical systems (MEMS) filter and how to use it efficiently (i.e., tuning the tuning-capability and avoiding both failure and stiction). LDV enables crucial measurements that are impossible with the network analyzer, such as higher mode detection (highly sensitive biosensor application) and resonance measurement for very small devices (fast prototyping)...
February 4, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29439429/plane-wave-sh%C3%A2-piezoceramic-transduction-optimized-using-geometrical-parameters
#2
Guillaume Boivin, Martin Viens, Pierre Belanger
Structural health monitoring is a prominent alternative to the scheduled maintenance of safety-critical components. The nondispersive nature as well as the through-thickness mode shape of the fundamental shear horizontal guided wave mode (SH 0 ) make it a particularly attractive candidate for ultrasonic guided wave structural health monitoring. However, plane wave excitation of SH 0 at a high level of purity remains challenging because of the existence of the fundamental Lamb modes (A 0 and S 0 ) below the cutoff frequency thickness product of high-order modes...
February 10, 2018: Sensors
https://www.readbyqxmd.com/read/29429820/direct-bone-conduction-stimulation-ipsilateral-effect-of-different-transducer-attachments-in-active-transcutaneous-devices
#3
Cristina Rigato, Sabine Reinfeldt, Bo Håkansson, Karl-Johan Fredén Jansson, Erik Renvall, Måns Eeg-Olofsson
Active transcutaneous bone conduction devices, where the transducer is implanted, are used for rehabilitation of hearing impaired patients by directly stimulating the skull bone. The transducer and the way it is attached to the bone play a central role in the design of such devices. The actual effect of varying the contact to bone has not been addressed yet. The aim of this study is therefore to compare how different attachment methods of the transducer to the bone for direct stimulation affect the ear canal sound pressure and vibration transmission to the ipsilateral cochlea...
January 31, 2018: Hearing Research
https://www.readbyqxmd.com/read/29417191/-new-clinical-applications-for-laser-doppler-vibrometry-in-otology
#4
REVIEW
T Strenger, M Brandstetter, T Stark, F Böhnke
BACKGROUND: An instrument to measure vibration in the middle ear needs to be sensitive enough to detect displacement on a nanometer scale, yet not affect the vibration itself. Numerous techniques have been described in the literature, but laser Doppler vibrometry (LDV) has nowadays become established as the standard method in hearing research. OBJECTIVE: This article aims to present possible clinical applications of an LDV system in otology. MATERIALS AND METHODS: A commercially available single-point vibrometer was used...
February 7, 2018: HNO
https://www.readbyqxmd.com/read/29389658/full-wavefield-analysis-and-damage-imaging-through-compressive-sensing-in-lamb-wave-inspections
#5
Yasamin Keshmiri Esfandabadi, Luca De Marchi, Nicola Testoni, Alessandro Marzani, Guido Masetti
One of the main challenges faced by the structural health monitoring community is acquiring and processing huge sets of acoustic wavefield data collected from sensors, such as scanning laser Doppler vibrometers or ultrasonic scanners. In fact, extracting information that allows the estimation of the damage condition of a structure can be a time-consuming process. This paper presents a damage detection and localization technique based on a compressive sensing algorithm, which significantly allows us to reduce the acquisition time without losing in detection accuracy...
February 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29364847/sensing-performance-analysis-on-quartz-tuning-fork-probe-at-the-high-order-vibration-mode-for-multi-frequency-scanning-probe-microscopy
#6
Xiaofei Zhang, Fengli Gao, Xide Li
Multi-frequency scanning near-field optical microscopy, based on a quartz tuning fork-probe (QTF-p) sensor using the first two orders of in-plane bending symmetrical vibration modes, has recently been developed. This method can simultaneously achieve positional feedback (based on the 1st in-plane mode called the low mode) and detect near-field optically induced forces (based on the 2nd in-plane mode called the high mode). Particularly, the high mode sensing performance of the QTF-p is an important issue for characterizing the tip-sample interactions and achieving higher resolution microscopic imaging but the related researches are insufficient...
January 24, 2018: Sensors
https://www.readbyqxmd.com/read/29054338/non-contact-and-through-clothing-measurement-of-the-heart-rate-using-ultrasound-vibrocardiography
#7
Nathan Jeger-Madiot, Jérôme Gateau, Mathias Fink, Ros-Kiri Ing
We present a novel non-contact system for monitoring the heart rate on human subjects with clothes. Our approach is based on vibrocardiography, and measures locally skin displacements. Vibrocardiography with a laser Doppler vibrometer already allows monitoring of this vital sign, but can only be used on bare skin and requires an expensive piece of equipment. We propose here to use an airborne pulse-Doppler ultrasound system operating in the 20-60 kHz range, and comprised of an emitter focusing the ultrasound pulses on skin and a microphone recording the reflected waves...
December 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29054109/influence-of-backside-loading-on-the-floating-mass-transducer-an-in-vitro-experimental-study
#8
Antoniu-Oreste Gostian, Martin Sylvester Otte, David Pazen, Magdalene Ortmann, David Schwarz, Karl Bernd Hüttenbrink, Dirk Beutner
HYPOTHESIS: The vibration of the floating mass transducer (FMT) of a single active middle-ear implant (AMEI) is distinctly influenced by the properties of the material coupled to its back side. BACKGROUND: In round window vibroplasty, the FMT needs to be padded against the surrounding bone opposite from the round window membrane. This represents one factor influencing its performance as a round window driver. Therefore, we examined the effects of different materials linked to the back side of an FMT on its vibration range...
October 20, 2017: Clinical Otolaryngology
https://www.readbyqxmd.com/read/28964568/sound-wave-propagation-on-the-human-skull-surface-with-bone-conduction-stimulation
#9
Ivo Dobrev, Jae Hoon Sim, Stefan Stenfelt, Sebastian Ihrle, Rahel Gerig, Flurin Pfiffner, Albrecht Eiber, Alexander M Huber, Christof Röösli
BACKGROUND: Bone conduction (BC) is an alternative to air conduction to stimulate the inner ear. In general, the stimulation for BC occurs on a specific location directly on the skull bone or through the skin covering the skull bone. The stimulation propagates to the ipsilateral and contralateral cochlea, mainly via the skull bone and possibly via other skull contents. This study aims to investigate the wave propagation on the surface of the skull bone during BC stimulation at the forehead and at ipsilateral mastoid...
September 23, 2017: Hearing Research
https://www.readbyqxmd.com/read/28772431/inspection-of-piezoceramic-transducers-used-for-structural-health-monitoring
#10
Inka Mueller, Claus-Peter Fritzen
The use of piezoelectric wafer active sensors (PWAS) for structural health monitoring (SHM) purposes is state of the art for acousto-ultrasonic-based methods. For system reliability, detailed information about the PWAS itself is necessary. This paper gives an overview on frequent PWAS faults and presents the effects of these faults on the wave propagation, used for active acousto-ultrasonics-based SHM. The analysis of the wave field is based on velocity measurements using a laser Doppler vibrometer (LDV). New and established methods of PWAS inspection are explained in detail, listing advantages and disadvantages...
January 16, 2017: Materials
https://www.readbyqxmd.com/read/28758555/sequential-motion-of-the-ossicular-chain-measured-by-laser-doppler-vibrometry
#11
Yasuomi Kunimoto, Kensaku Hasegawa, Shiro Arii, Hideyuki Kataoka, Hiroaki Yazama, Junko Kuya, Kazunori Fujiwara, Hiromi Takeuchi
OBJECTIVE: In order to help a surgeon make the best decision, a more objective method of measuring ossicular motion is required. METHODS: A laser Doppler vibrometer was mounted on a surgical microscope. To measure ossicular chain vibrations, eight patients with cochlear implants were investigated. To assess the motions of the ossicular chain, velocities at five points were measured with tonal stimuli of 1 and 3 kHz, which yielded reproducible results. The sequential amplitude change at each point was calculated with phase shifting from the tonal stimulus...
July 31, 2017: Acta Oto-laryngologica
https://www.readbyqxmd.com/read/28666703/a-comparative-study-of-med-el-fmt-attachment-to-the-long-process-of-the-incus-in-intact-middle-ears-and-its-attachment-to-disarticulated-stapes-head
#12
Tao Chen, Liu-Jie Ren, Dong-Ming Yin, Jia Li, Lin Yang, Pei-Dong Dai, Tian-Yu Zhang
The Vibrant Soundbridge(©) (VSB) active middle-ear implant provides an effective treatment for mild-to-severe sensorineural hearing loss in the case of normal middle ear anatomy and mixed hearing loss in middle ear malformation. The VSB floating mass transducer (FMT), with proper couplers, can be installed on various structures of the ossicular chain, e.g., the short and long process of the incus, the stapes head, and the stapes footplate. A long process (LP) coupler is most commonly used for FMT attachment to the long process of the incus with intact ossicular chain, while CliP and Bell couplers are two standardized and reliable methods for FMT attachment to the stapes head with missing incus and malleus...
June 23, 2017: Hearing Research
https://www.readbyqxmd.com/read/28657955/the-hannover-coupler-controlled-static-prestress-in-round-window-stimulation-with-the-floating-mass-transducer
#13
Mathias Müller, Rolf Salcher, Thomas Lenarz, Hannes Maier
INTRODUCTION: Stimulation of the cochlear round window (RW) with the floating mass transducer (FMT) still suffers from large variation in clinical outcomes. Beside the geometric mismatch between RW and FMT diameter that is a known limiting factor in achieving optimal coupling between actuator and RW membrane, the applied static force between FMT and RW is usually undefined. In this study, the feasibility and efficacy of a specially designed FMT coupler permitting application of static preloads to the RW membrane to optimize FMT-RW coupling was investigated...
September 2017: Otology & Neurotology
https://www.readbyqxmd.com/read/28601531/sheep-as-a-large-animal-ear-model-middle-ear-ossicular-velocities-and-intracochlear-sound-pressure
#14
Dominik Péus, Ivo Dobrev, Lukas Prochazka, Konrad Thoele, Adrian Dalbert, Andreas Boss, Nicolas Newcomb, Rudolf Probst, Christof Röösli, Jae Hoon Sim, Alexander Huber, Flurin Pfiffner
Animals are frequently used for the development and testing of new hearing devices. Dimensions of the middle ear and cochlea differ significantly between humans and commonly used animals, such as rodents or cats. The sheep cochlea is anatomically more like the human cochlea in size and number of turns. This study investigated the middle-ear ossicular velocities and intracochlear sound pressure (ICSP) in sheep temporal bones, with the aim of characterizing the sheep as an experimental model for implantable hearing devices...
August 2017: Hearing Research
https://www.readbyqxmd.com/read/28515236/resonance-frequencies-of-honeybee-apis-mellifera-wings
#15
Christopher J Clark, Andrew M Mountcastle, Emily Mistick, Damian O Elias
During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees (Apis mellifera) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a Scanning Doppler Laser Vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode, and at 602±145 Hz, greater than the wingbeat frequency of 234 Hz±13...
May 17, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28481267/inkjet-printed-membrane-for-a-capacitive-acoustic-sensor-development-and-characterization-using-laser-vibrometer
#16
Rubaiyet Iftekharul Haque, Erick Ogam, Patrick Benaben, Xavier Boddaert
This paper describes the fabrication process and the method to determine the membrane tension and defects of an inkjet-printed circular diaphragm. The membrane tension is an important parameter to design and fabricate an acoustic sensor and resonator with the highest sensitivity and selectivity over a determined range of frequency. During this work, the diaphragms are fabricated by inkjet printing of conductive silver ink on pre-strained Mylar thin films, and the membrane tension is determined using the resonant frequency obtained from its measured surface velocity response to an acoustic excitation...
May 6, 2017: Sensors
https://www.readbyqxmd.com/read/28372141/optical-imaging-of-propagating-mach-cones-in-water-using-refracto-vibrometry
#17
Nathan R Huber, Thomas M Huber, Matthew T Huber
Refracto-vibrometry was used to optically image propagating Mach cones in water. These Mach cones were produced by ultrasonic longitudinal and shear waves traveling through submerged 12.7 mm diameter metal cylinders. Full-field videos of the propagating wave fronts were obtained using refracto-vibrometry. A laser Doppler vibrometer, directed at a retroreflective surface, sampled time-varying water density at numerous scan points. Wave speeds were determined from the Mach cone apex angles; the measured longitudinal and shear wave speeds in steel (6060 ± 170 m/s and 3310 ± 110 m/s, respectively) and beryllium (12 400 ± 700 m/s and 8100 ± 500 m/s) agreed with published values...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28320655/a-study-on-the-effects-of-release-area-on-the-quality-factor-of-contour-mode-resonators-by-laser-doppler-vibrometry
#18
Brian Gibson, Kamala Qalandar, Cristian Cassella, Gianluca Piazza, Kimberly L Foster
Through the use of a laser Doppler vibrometer, it is shown that a 31% variation in quality factor can occur due to the effect of undercutting of the device layers outside of the anchors of a 220-MHz aluminum nitride contour-mode resonator. This undercutting is a result of the isotropic etch process used to release the device from the substrate. This paper shows that the variation in Q is a function of the release distance, L , between the active region of the resonator and the edge of this released region. This paper also determined a design modification that eliminated this issue and achieved a Q of 3048, which is independent of L ...
May 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28253676/time-reversal-focusing-of-elastic-waves-in-plates-for-an-educational-demonstration
#19
Christopher Heaton, Brian E Anderson, Sarah M Young
The purpose of this research is to develop a visual demonstration of time reversal focusing of vibrations in a thin plate. Various plate materials are tested to provide optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the vibration coupling efficiency from a shaker to the plate are quantified to illustrate why a given plate provides the best spatially confined focus as well as the highest focal amplitude possible. A single vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing...
February 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28231638/comparison-of-the-shock-absorption-capacities-of-different-mouthguards
#20
Melina Simonetta Bochnig, Min-Jung Oh, Theresa Nagel, Fred Ziegler, Paul-Georg Jost-Brinkmann
BACKGROUND/AIMS: In this in vitro study, the protective qualities of different mouthguard types were examined during small hard object collisions. The aim was to investigate inconclusive aspects of hard inserts, nylon nets, and air spaces as reinforcements in the anterior region and the protection qualities of ethylene vinyl acetate (EVA). MATERIALS AND METHODS: Five different mouthguards with a labial thickness between 2 mm and 11 mm made of materials of varying stiffness were investigated...
February 23, 2017: Dental Traumatology: Official Publication of International Association for Dental Traumatology
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