Showing papers on "Transducer published in 2020"
TL;DR: In this paper, a low-cost, bi-stable piezoelectric energy harvester is proposed, analyzed, and experimentally tested for the purpose of broadband energy harvesting.
87 citations
TL;DR: In this paper, a mechanical oscillatory mechanism is used to accumulate ambient kinetic energy, prior to the conversion to electrical energy through a transducer, which is referred to as vibration energy harvesting.
Abstract: Vibration energy harvesting typically involves a mechanical oscillatory mechanism to accumulate ambient kinetic energy, prior to the conversion to electrical energy through a transducer. The conven...
84 citations
TL;DR: In this article, the properties of these blends, such as ultimate stress and strain, Young's modulus, dielectric permittivity, breakdown strength, viscosity, leakage current and optical transmittance, are investigated and mapped to identify those exhibiting the best-suited properties for fabricating soft and stretchable transducers.
Abstract: Elastomers for fabricating soft and stretchable transducers primarily require high elongation at break, high dielectric permittivity, high breakdown strength and low leakage current. Commercial silicone elastomer formulations often do not encompass all of the properties necessary to function effectively as stretchable transducers, but they are nevertheless used out of familiarity. On a research level, Sylgard 184, Sylgard 186, Ecoflex 00-10, Ecoflex 00-30 and Ecoflex 00-50 are widely used for fabricating stretchable devices. We blend these commercial silicones with each other in various proportions, to make the blends most suitable for fabricating specific types of transducers. Furthermore, the properties of these blends, such as ultimate stress and strain, Young's modulus, dielectric permittivity, breakdown strength, viscosity, leakage current and optical transmittance, are investigated and mapped to identify those exhibiting the best-suited properties for fabricating soft and stretchable transducers. The elastomers obtained using the blending methods illustrated herein could act as a starting point for conceptualizing the feasibility of a product on a research level.
77 citations
Posted Content•
TL;DR: It is demonstrated that T-T outperforms the hybrid model, RNN Transducer (RNN-T), and streamable Transformer attention-based encoder-decoder model in the streaming scenario and the runtime cost and latency can be optimized with a relatively small look-ahead.
Abstract: Recently, Transformer based end-to-end models have achieved great success in many areas including speech recognition. However, compared to LSTM models, the heavy computational cost of the Transformer during inference is a key issue to prevent their applications. In this work, we explored the potential of Transformer Transducer (T-T) models for the fist pass decoding with low latency and fast speed on a large-scale dataset. We combine the idea of Transformer-XL and chunk-wise streaming processing to design a streamable Transformer Transducer model. We demonstrate that T-T outperforms the hybrid model, RNN Transducer (RNN-T), and streamable Transformer attention-based encoder-decoder model in the streaming scenario. Furthermore, the runtime cost and latency can be optimized with a relatively small look-ahead.
71 citations
TL;DR: An overview on various ultrasound transducer technologies including conventional piezoelectric and micromachined transducers, as well as optical ultrasound detection technology, explaining the core components of each technology, their working principle, and describe their manufacturing process.
Abstract: Ultrasound detection is one of the major components of photoacoustic imaging systems. Advancement in ultrasound transducer technology has a significant impact on the translation of photoacoustic imaging to the clinic. Here, we present an overview on various ultrasound transducer technologies including conventional piezoelectric and micromachined transducers, as well as optical ultrasound detection technology. We explain the core components of each technology, their working principle, and describe their manufacturing process. We then quantitatively compare their performance when they are used in the receive mode of a photoacoustic imaging system.
71 citations
TL;DR: Ultimate FHE technologies are demonstrated to achieve efficient closed‐loop systems for healthcare management, medical diagnostics, and preclinical studies in neuroscience and neuroengineering.
Abstract: Mechanically and visually imperceptible sensor sheets integrated with lightweight wireless loggers are employed in ultimate flexible hybrid electronics (FHE) to reduce vital stress/nervousness and monitor natural biosignal responses. The key technologies and applications for conceptual sensor system fabrication are reported, as exemplified by the use of a stretchable sensor sheet completely conforming to an individual's body surface to realize a low-noise wireless monitoring system (<1 µV) that can be attached to the human forehead for recording electroencephalograms. The above system can discriminate between Alzheimer's disease and the healthy state, thus offering a rapid in-home brain diagnosis possibility. Moreover, the introduction of metal nanowires to improve the transparency of the biocompatible sensor sheet allows one to wirelessly acquire electrocorticograms of nonhuman primates and simultaneously offers optogenetic stimulation such as toward-the-brain-machine interface under free movement. Also discussed are effective methods of improving electrical reliability, biocompatibility, miniaturization, etc., for metal nanowire based tracks and exploring the use of an organic amplifier as an important component to realize a flexible active probe with a high signal-to-noise ratio. Overall, ultimate FHE technologies are demonstrated to achieve efficient closed-loop systems for healthcare management, medical diagnostics, and preclinical studies in neuroscience and neuroengineering.
64 citations
TL;DR: In this paper, phase structure engineered high-performance potassium sodium niobate [(K,Na)NbO3, KNN]-based ceramics and its potential application on ultrasonic transducers were presented.
56 citations
19 May 2020
TL;DR: It is found that the transducer model generalizes much better on longer sequences than the attention model, and outperforms the authors' attention model on Switchboard 300h by over 6% relative WER.
Abstract: The RNN transducer is a promising end-to-end model candidate. We compare the original training criterion with the full marginalization over all alignments, to the commonly used maximum approximation, which simplifies, improves and speeds up our training. We also generalize from the original neural network model and study more powerful models, made possible due to the maximum approximation. We further generalize the output label topology to cover RNN-T, RNA and CTC. We perform several studies among all these aspects, including a study on the effect of external alignments. We find that the transducer model generalizes much better on longer sequences than the attention model. Our final transducer model outperforms our attention model on Switchboard 300h by over 6% relative WER.
55 citations
TL;DR: In this article, an ultra high sensitive quasi-distributed acoustic sensor based on coherent detection and cylindrical transducer is proposed and demonstrated, which integrates a series of high-sensitive sensing units in a single fiber.
Abstract: Highly sensitive distributed acoustic sensor is required in various practical applications. In this article, an ultra high sensitive quasi distributed acoustic sensor based on coherent detection and cylindrical transducer is proposed and demonstrated. As the acoustic sensing medium, distributed microstructured optical fiber (DMOF) is utilized to improve the signal to noise ratio (SNR) of the signal, which contains backscattering enhanced points (BEPs) along the longitudinal direction of the fiber. In order to increase the acoustic sensitivity, the hollow cylindrical structure is developed for acoustic wave transduction. In addition, coherent phase detection is adopted to achieve the high precision phase signal demodulation, and thus to realize high-fidelity recovery of the airborne sound wave. Consequently, the spatial distributed acoustic sensing can be realized, which integrates a series of high-sensitive sensing units in a single fiber. The field test results of the airborne sound detection illustrate an excellent phase sensitivity of −112.5 dB ( re 1 rad/μPa) within the flat frequency range of 500 Hz–5 kHz and a peak sensitivity up to −83.7 dB ( re 1 rad/μPa) at 80Hz. The waveform comparison between the measurement result and the standard signal shows the maximum error of only 3.07%. Besides, distributed audio signal recovery and spatial acoustic imaging are demonstrated, which can be further applied in the field of fiber distributed microphone and urban noise intensity holography.
54 citations
TL;DR: In this paper, a real-time nonlinear ultrasonic method based on vibro-acoustic modulation is applied to monitor early bolt looseness quantitatively by using piezoceramic transducers.
Abstract: A real-time nonlinear ultrasonic method based on vibro-acoustic modulation is applied to monitor early bolt looseness quantitatively by using piezoceramic transducers. In addition to the ability to...
45 citations
20 Dec 2020
TL;DR: In this paper, an integrated electro-optic transducer that combines low-loss lithium niobate photonics with superconducting microwave resonators on a sapphire substrate is presented.
Abstract: Quantum networks are likely to have a profound impact on the way we compute and communicate in the future. In order to wire together superconducting quantum processors over kilometer-scale distances, we need transducers that can generate entanglement between the microwave and optical domains with high fidelity. We present an integrated electro-optic transducer that combines low-loss lithium niobate photonics with superconducting microwave resonators on a sapphire substrate. Our triply resonant device operates in a dilution refrigerator and converts microwave photons to optical photons with an on-chip efficiency of 6.6×10−6 and a conversion bandwidth of 20 MHz. We discuss design trade-offs in this device, including strategies to manage acoustic loss, and outline ways to increase the conversion efficiency in the future.
Posted Content•
TL;DR: In this article, an integrated electro-optic transducer that combines low-loss lithium niobate photonics with superconducting microwave resonators on a sapphire substrate is presented.
Abstract: Quantum networks are likely to have a profound impact on the way we compute and communicate in the future. In order to wire together superconducting quantum processors over kilometer-scale distances, we need transducers that can generate entanglement between the microwave and optical domains with high fidelity. We present an integrated electro-optic transducer that combines low-loss lithium niobate photonics with superconducting microwave resonators on a sapphire substrate. Our triply-resonant device operates in a dilution refrigerator and converts microwave photons to optical photons with an on-chip efficiency of $6.6\times 10^{-6}$ and a conversion bandwidth of 20 MHz. We discuss design trade-offs in this device, including strategies to manage acoustic loss, and outline ways to increase the conversion efficiency in the future.
TL;DR: In this paper, a water droplet sensor based on a flow-through front surface electrode is demonstrated, where every water drop generates a flash in a light emitting diode, which is detected by a silicon photodetector located some distance away.
TL;DR: A novel perfect edge reflector is proposed with elimination of longitudinal spurious ripples in the design of the SH0 plate acoustic wave (PAW) resonators, applicable to the ultra-wideband filters and next-generation tunable filters.
Abstract: This study lays a foundation for the design of the SH0 plate acoustic wave (PAW) resonators based on LiNbO3 plate, and are applicable to the ultra-wideband filters and next-generation tunable filters. The coupling coefficient ( $k^{2}$ ) of SH0 mode is optimized to as high as 55% and wideband spurious are well controlled by analyzing the propagation characteristics of plate modes in LiNbO3. The SH0 mode is demonstrated to be slowly dispersive and features the superiority of interdigital transducer (IDT)—defining frequency over most other plate modes. On the device level, the transducer types and electrode materials are investigated and compared. In addition, for edge-reflected SH0 resonators, stopband dispersion analysis is provided and the longitudinal ripples are suppressed. For edge-reflected SH0 resonators, a novel perfect edge reflector is proposed with elimination of longitudinal spurious ripples.
TL;DR: In this article, the suitability of a Piezoelectric Micromachined Ultrasound Transducer (PMUT) based system for fluid density measurement in both static and dynamic conditions was investigated.
Abstract: We report on the suitability of a Piezoelectric Micromachined Ultrasound Transducer (PMUT) based system for fluid density measurement in both static and dynamic conditions. We exploit the well-known phenomenon of the virtual added mass induced changes in the resonant frequency of a structure vibrating in a fluid medium to design, fabricate and test a unique PMUT-fluid-PMUT (PFP) system as a fluid density sensor. The proposed system uses through-transmission of ultrasound waves from one PMUT transducer to another identical transducer with the test fluid in between and records the shift in the resonant peak of the receiver PMUT. We also study the sensitivity of the system using different sized PMUTs with resonant frequencies ranging from 140 kHz to 1.8 MHz and show how the system can be designed for a desired sensitivity. Further, we carry out experiments with dynamic density changes by mixing fluids to study how the system could be used to track changes in the density of a flowing liquid in real-time. We also study the effect of the distance separating the transmitter and the receiver to establish the utility of the system in both micro and macro scales in static as well as dynamic conditions.
TL;DR: The acoustic characterization suggests that the −6 dB fractional bandwidth and transmitting sensitivity of the prototyped transducer are promising for nondestructive testing, biomedical imaging, and therapy.
Abstract: In this article, a flexible piezo-composite transducer composed of the active piezoelectric material (PZT-5H) and passive polymer matrix [polydimethylsiloxane (PDMS)] is developed to achieve excellent flexibility, sensitivity, and bandwidth for biomedical and industrial applications. The flexible electrodes [silver nanowires (AgNWs) mixed with PDMS] are deposited on the transducers using a spray coating method, providing a sufficient conductivity of an electrode through repeated bending tests. The flexible 1–3 composite transducer exhibits robust mechanical flexibility (curved radius <5 mm) without failure due to the stretchable mechanical properties of PDMS and AgNWs network, which indicates that the AgNW/PDMS electrode is a promising alternative to conventional metal-type electrodes, such as Au film. The acoustic characterization suggests that the −6 dB fractional bandwidth (∼49%) and transmitting sensitivity (∼107 mV/V) of the prototyped transducer are promising for nondestructive testing, biomedical imaging, and therapy.
TL;DR: The development of an optically transparent high-frequency ultrasonic transducer using lithium niobate single-crystal and indium–tin–oxide electrodes with up to 90% optical transmission in the visible-to-near-infrared spectrum is reported.
Abstract: We report the development of an optically transparent high-frequency ultrasonic transducer using lithium niobate single-crystal and indium–tin–oxide electrodes with up to 90% optical transmission in the visible-to-near-infrared spectrum. The center frequency of the transducer was at 36.9 MHz with 33.9%, at −6 dB fractional bandwidth. The photoacoustic imaging capability of the fabricated transducer was also demonstrated by successfully imaging a resolution target and mouse-ear vasculatures in vivo , which were irradiated by a 532 nm pulse laser transmitted through the transducer.
TL;DR: In this article, a focused optically-transparent ultrasound transducer with a wide bandwidth for photoacoustic microscopy (PAM) is presented, which consists of a 9-mu \text{m}$ -thick polyvinylidene fluoride (PVDF) film coated with Indium-tin oxide (ITO) and metal electrodes, which is laminated onto a concave glass lens.
Abstract: This papers reports the development of a novel focused optically-transparent ultrasound transducer with a wide bandwidth for photoacoustic microscopy (PAM). It consists of a 9- $\mu \text{m}$ -thick polyvinylidene fluoride (PVDF) film coated with Indium-tin oxide (ITO) and metal electrodes, which is laminated onto a concave glass lens. A new fabrication process was developed to ensure the formation of continuous ITO coatings on the curved transducer surface without fracturing. Both optical and acoustic experiments were conducted to characterize the performance of the transducer. The testing results show that the transducer has an optical transmittance of 60% (@ 532 nm), an acoustic center frequency of 24 MHz, and an acoustic bandwidth of 26 MHz. With an acoustic numerical aperture (NA) of 0.23, it provides a 0.13-mm acoustic focal spot and a 1.6-mm focal depth. For demonstration, a PAM setup was built for conducting PA imaging on different targets. In contrast to existing PAM systems, the use of the optically-transparent focused transducer allows a simpler and more compact configuration and easier alignment of the optical excitation and acoustic focal points. Such features are especially useful for the development of miniaturized PAM systems for handheld, wearable and even endoscopic applications.
TL;DR: The possibility of taking advantage of the isoplanatic angle of the aberrating skull in order to steer the focus by mechanically moving the transducer/acoustic lens pair around its initial focusing position is demonstrated.
Abstract: For successful brain therapy, transcranial focused ultrasound must compensate for the time shifts induced locally by the skull. The patient-specific phase profile is currently generated by multi-element arrays which, over time, have tended toward increasing element count. We recently introduced a new approach, consisting of a single-element transducer coupled to an acoustic lens of controlled thickness. By adjusting the local thickness of the lens, we were able to induce phase differences which compensated those induced by the skull. Nevertheless, such an approach suffers from an apparent limitation: the lens is a priori designed for one specific target. In this paper, we demonstrate the possibility of taking advantage of the isoplanatic angle of the aberrating skull in order to steer the focus by mechanically moving the transducer/acoustic lens pair around its initial focusing position. This study, conducted on three human skull samples, demonstrates that tilting of the transducer with the lens restores a single −3 dB focal volume at 914 kHz for a steering up to ±11 mm in the transverse direction, and ±10 mm in the longitudinal direction, around the initial focal region.
TL;DR: In this paper, the authors used an adhesive wafer bonding technique using photosensitive benzocyclobutene (BCB) as both a structural and adhesive layer with a glass-indium-tin-oxide (ITO) substrate.
Abstract: Photoacoustic imaging has shown great potential for non-invasive high-resolution deep-tissue imaging. Minimizing the optical and acoustic paths for excitation and detection could significantly increase the signal-to-noise ratio. This could be accomplished by transparent transducers permitting through-transducer illumination. However, most ultrasound transducers are not optically transparent. Capacitive micromachined ultrasound transducer (CMUT) technology has compelling properties compared to piezoelectric transducers such as wide bandwidth and high receive sensitivity. Here, we introduce transparent CMUT linear arrays with high transparency in the visible and near-infrared range. To fabricate the devices, we used an adhesive wafer bonding technique using photosensitive benzocyclobutene (BCB) as both a structural and adhesive layer with a glass-indium-tin-oxide (ITO) substrate. Silicon nitride is used as the membrane material ensuring hermiticity and optical transparency. Our fabricated transducer arrays consist of 64 and 128 elements with immersion operation frequency of 8 MHz, enabling high-resolution imaging. ITO, along with thin metal strips, are used as a conductive layer for the top electrodes with minimal impact on device transparency. Fabricated devices have shown average transparency of 70% in the visible wavelength range that goes up to 90% in the near-infrared range. Arrays are wire-bonded to interfacing electronics and connected to a research ultrasound platform for phantom imaging. Arrays exhibited signal-to-noise (SNR) of 40 dB with 30V bias voltage and laser fluence of 13.5 mJ/cm2. Arrays with 128 channels provided lateral and axial resolutions of 234 µm and 220 µm, respectively.
27 Apr 2020
TL;DR: In this article, the authors present a platform for electro-optic photon conversion based on silicon-organic hybrid photonics, which combines high quality factor microwave and optical resonators with an electrooptic polymer cladding to perform microwave-to-optical photon conversion from 6.7 GHz to 193 THz.
Abstract: Low-loss fiber optic links have the potential to connect superconducting quantum processors together over long distances to form large scale quantum networks. A key component of these future networks is a quantum transducer that coherently and bidirectionally converts photons from microwave frequencies to optical frequencies. We present a platform for electro-optic photon conversion based on silicon-organic hybrid photonics. Our device combines high quality factor microwave and optical resonators with an electro-optic polymer cladding to perform microwave-to-optical photon conversion from 6.7 GHz to 193 THz (1558 nm). The device achieves an electro-optic coupling rate of 590 Hz in a millikelvin dilution refrigerator environment. We use an optical heterodyne measurement technique to demonstrate the single-sideband nature of the conversion with a selectivity of approximately 10 dB. We analyze the effects of stray light in our device and suggest ways in which this can be mitigated. Finally, we present initial results on high-impedance spiral resonators designed to increase the electro-optic coupling.
TL;DR: This new temperature compensation procedure was applied to a set of guided wave signals collected in a blind trial of a guided wave pipe monitoring system, yielding residuals de-coupled from temperature and reduced by at least 50% as compared with those obtained using the standard approach.
Abstract: In guided wave structural health monitoring, defects are typically detected by identifying high residuals obtained through the baseline subtraction method, where an earlier measurement is subtracted from the “current” signal. Unfortunately, varying environmental and operational conditions (EOCs), such as temperature, also produce signal changes and hence, potentially, high residuals. While the majority of the temperature compensation methods that have been developed target the changed wave speed induced by varying temperature, a number of other effects are not addressed, such as the changes in attenuation, the relative amplitudes of different modes excited by the transducer, and the transducer frequency response. A temperature compensation procedure is developed, whose goal is to correct any spatially dependent signal change that is a systematic function of temperature. At each structural position, a calibration function that models the signal variation with temperature is computed and is used to correct the measurements, so that in the absence of a defect the residual is reduced to close to zero. This new method was applied to a set of guided wave signals collected in a blind trial of a guided wave pipe monitoring system using the T(0, 1) mode, yielding residuals de-coupled from temperature and reduced by at least 50% as compared with those obtained using the standard approach at positions away from structural features, and by more than 90% at features such as the pipe end. The method, therefore, promises a substantial improvement in the detectability of small defects, particularly at the existing pipe features.
TL;DR: In this article, a compressivemode high-power-density piezoelectric transducer for harvesting vibration energy from spring suspension systems is presented, which can reach an average output power of 1363mW at the resonant frequency of 463Hz under the 03g harmonic excitation with the 1975kΩ matched impedance.
TL;DR: In this paper, a pneumatic piezoelectric vibration energy harvester (PVEH) based on compressed air-transducer-structure interaction is presented and fabricated.
TL;DR: This study designed a convolutional neural network called a ring-array deep learning network (RADL-net), which can eliminate limited-view and under-sampling artifacts in PAT images and is superior to the conventional compressed sensing (CS) algorithm.
Patent•
24 Jan 2020
TL;DR: In this paper, the authors proposed a communication method for the technical field of computer application, and the method comprises the steps: obtaining to-be-transmitted electric signal information, determining emission information corresponding to the electric signal according to a preset vortex sound field generation mode, converting the electric signals into vortex sound signals corresponding to transmitting information through a preset transmitting transducer array, and transmitting the vortex sound signal.
Abstract: The invention is suitable for the technical field of computer application, and provides a communication method and device, and the method comprises the steps: obtaining to-be-transmitted electric signal information; determining emission information corresponding to the electric signal information according to a preset vortex sound field generation mode; converting the electric signal information into a vortex sound field signal corresponding to the transmitting information through a preset transmitting transducer array; and transmitting the vortex sound field signal. The transmitting information of the vortex sound field signal corresponding to the electric signal information is determined according to the preset vortex sound field generating mode, any vortex sound field is generated or received through the preset underwater transducer array, core sound field propagation of vortex sound communication is achieved, and distortion of underwater transmitted signals in the encoding and decoding process is reduced.
TL;DR: A −10 V electret-augmented actuator with an out-of-plane motion membrane reached a sound pressure level (SPL) of 50 dB maximum with AC input voltage of Vin=5 Vpp alone, indicating a potential for acoustic transducer usage such as microspeakers.
Abstract: Despite the development of energy-efficient devices in various applications, microelectromechanical system (MEMS) electrostatic actuators yet require high voltages to generate large displacements. In this respect, electrets exhibiting quasi-permanent electrical charges allow large fixed voltages to be integrated directly within electrode structures to reduce or eliminate the need of DC bias electronics. For verification, a − 40 V biased electret layer was fabricated at the inner surface of a silicon on insulator (SOI) structure facing a 2 μm gap owing to the high compatibility of silicon micromachining and the potassium-ion-electret fabrication method. A − 10 V electret-augmented actuator with an out-of-plane motion membrane reached a sound pressure level (SPL) of 50 dB maximum with AC input voltage of V i n = 5 V pp alone, indicating a potential for acoustic transducer usage such as microspeakers. Such devices with electret biasing require only the input signal voltage, thus contributing to reducing the overall power consumption of the device system.
TL;DR: It is concluded that defect detection and localization with Lamb mode conversion is possible with an air coupled ultrasonic setup.
TL;DR: In this paper, the experimental verification of an enhanced energy conversion device utilizing a tuned inerter called a tuned inertial mass electromagnetic transducer (TIMET) is presented.
Abstract: This research reports on the experimental verification of an enhanced energy conversion device utilizing a tuned inerter called a tuned inertial mass electromagnetic transducer (TIMET). The TIMET c...