Types Of Transducers Research Articles

All Acoustical Excitation of Spin Waves in High Overtone Bulk Acoustic Resonator

The hybrid high overtone bulk acoustic wave resonators (HBARs) consisting of a piezoelectric film transducers and gallium gadolinium garnet substrates with yttrium iron garnet films (YIG-GGG-YIG) are used for experimental excitation and detection of acoustically driven spin waves (ADSWs). Two types of HBAR transducers made of Al-ZnO-Al films (differed through the electrodes’ geometry) were deposited onto YIG-GGG-YIG trilayers with different YIG film thicknesses and doping levels and served for excitation of multimode HBAR at gigahertz frequencies. ADSWs were detected by measuring the shifts of resonant HBAR modes in a tangential external magnetic field when the conditions for magnetoelastic resonance (MER) were satisfied. It was shown that the design of the transducer with a continuous bottom electrode provides all acoustical excitation of spin waves (pure ADSWs), suppressing the additional inductive magnetic dynamics excitation due to the electrodes’ geometry. The theoretical study of the HBAR spectrum in a magnetic field showed that the resonance harmonics in the MER region can either almost continuously transfer from one to another, or decay and form an evident magnetoelastic gap. In this case, the shift of resonant frequencies can achieve several intermodal distances. The results obtained are important for applications of HBAR-based devices in spintronics and magnonics.

Modeling and analysis of frequency-variable 2–2 cement-based piezoelectric transducers

The 2–2 cement-based piezoelectric transducers can be used as high-performance actuators and sensors. However, the existing designs with fixed electromechanical properties cannot meet some special application requirements, such as the tuning working frequency to achieve high precision monitoring purpose. To address this issue, a type of frequency-variable 2–2 cement-based piezoelectric transducers is proposed in this paper. Theoretical models of the proposed transducer are established, and the analytical solutions of its longitudinal vibration are obtained. The theoretical models are verified by comparing their results with those of the existing literature for some special examples, and with the finite element results for a special case. In addition, the effects of the tuning resistance, the ratio of piezoelectric layer numbers between the active and passive elements, the electrical connections of piezoelectric layers, and the total number of piezoelectric layers on the electromechanical properties of transducer are discussed. It is demonstrated that the proposed frequency-variable 2–2 cement-based piezoelectric transducers can obtain a large tunable bandwidth by adjusting the appropriate ratio of piezoelectric layer numbers between the active and passive elements and their electrical connections, which provides a theoretical basis for designing and optimizing this type of transducers.

Noninvasive liquid level sensing with laser generated ultrasonic waves

This article proposes a noninvasive liquid level sensing technique using laser-generated ultrasound waves for nuclear power plant applications. Liquid level sensors play an important role of managing the coolant system safely and stably in the plant structure. Current sensing techniques are mostly intrusive, performing inside the fluidic structure, which is disadvantageous in terms of the regular maintenance of the plant system. Furthermore, typical intrusive sensors do not perform stably under varying environmental conditions such as temperature and radiation. In this study, sensing units are attached to the outer surface of a liquid vessel to capture guided ultrasound waves in a nonintrusive manner. The signal intensity of the guided wave dissipates when the signal interacts with the internal liquid media. The sensing mechanism is mathematically expressed as an index value to correlate the liquid level with the sensor signal. For the acoustic wave generation, laser-generated ultrasound was adopted instead of using typical contact type transducers. Following the simulation validation of the proposed concept, the performance of the developed sensor was confirmed through experimental results under elevated liquid temperature conditions. The nonlinear multivariable regression exhibited the best-fit to the datasets measured under the variable liquid level and temperature conditions.

Numerical Study of a Miniaturized, 1–3 Piezoelectric Composite Focused Ultrasound Transducer

This study aimed to develop an optimal methodology for the design of a miniaturized, 1–3 piezoelectric composite focused ultrasound transducer. Miniaturized focused ultrasound (FUS) devices, generally guided through catheters, have received considerable attention in the biomedical and ultrasound fields as they can overcome the technical restrictions of typical FUS transducers. However, miniaturized transducers cannot readily generate a high acoustic intensity because of their small aperture sizes and the vibration mode coupling. As such, 1–3 composite transducers, having a high electromechanical coupling and efficient vibration directivity, break through the current technical restrictions. However, the systematic methodology for designing miniaturized FUS transducers has not been thoroughly discussed so far. Therefore, in this study, we designed 1–3 piezoelectric composite transducers using analytical and numerical methods. Specifically, extensive parametric studies were performed through finite element analysis under the coupled field with piezoelectricity, structural vibration, and acoustic pressure. The simulation results confirmed that the optimal design of the 1–3 composite type transducer produces much higher (>160%) acoustic pressure output at the focal point than the single-phase device. Furthermore, the array type of the interstitial transducer was predicted to produce an unprecedented acoustic intensity of approximately 188 W/cm2 under a short duty cycle (1%). This study will provide valuable technical methodology for the development of interstitial, 1–3 composite FUS transducers and the selection of optimal design parameters.

Horn Antenna Analysis and Simulation for the 18-40 GHz Frequency Band

An antenna is a type of transducer that converts radio signals into alternating electromagnetic waves before transmitting them into space. Polarization is a phase in the selection and installation of an antenna. It can send and receive signals. An antenna is a metal structure that transmits or receives electromagnetic radiation. The antenna, on the other hand, connects the directing device to free space. It sends a signal from the generator into space through transmission cables. High-frequency double-ridged horn (DRH) antennas for electromagnetic compatibility (EMC) are built using a special technique. When using this technique, at the beginning, consider a standard DRH antenna that operates between 1 and 18 GHz. A detailed sensitivity analysis of the 1-18 GHz DRH antenna's structural characteristics addresses some of the DRH antenna's weaknesses, notably in terms of its radiation pattern at higher frequencies. After that, the design is frequency scaled up to support a greater frequency range. This technology might be used to build a wideband DRH antenna that can operate between 18 and 40 GHz. Because the new antenna has a lower frequency ratio of 1:12.2 compared to the normal antenna's 1:18 ratio, we may choose the appropriate frequency window for scaling up. A voltage standing wave ratio (VSWR) of less than a single main lobe that is uninterruptedly oriented along the horn axis and a minimum of 10 dB of acceptable broadband gain are all necessary. The resulting design was used to produce a prototype antenna that was smaller than previous commercial antennas. The dimensions and design objectives were used to develop the prototype.

Preliminary Study on the Fabrication of Multi-Layer Screen-Printed Electrode for Biosensor Application

ytical device that combines certain biological and physical elements. Several types of transducers are used for physical elements, such as optical, electrochemical, thermic, or gravimetric. Nowadays, electrochemical transducers have become widely used for the application of biomedical sensors. Electrochemical measurement devices called screen-printed electrodes (SPEs) are created by printing several types of ink on a ceramic or plastic substrate. SPEs enable speedy in-situ examination with high repeatability, sensitivity, and accuracy. In this study, SPEs were fabricated using a personalized CNC machine

“Electronic nose”-type chemosensory systems for detection of gaseous poisonous substances

The work is devoted to a study of the detection sensitivity and selectivity of a series of simulants of gaseous poisonous substances (PS). Two different sensor types were used, namely: 1) a quartz crystal microbalance (QCM), exhibiting a shift of the resonant frequency of quartz plates coated with calixarene thin layers, and 2) chemoresistive electrodes coated with layers of nanocomposites of intrinsically conducting polymers (ICP) changing their conductance under the influence of adsorbed gas molecules. The concentration of the analyzed volatile compounds varied within the range of 10 to 1000 ppm. The detection threshold ranged from 10 to 100 ppm depending on the analyzed substance for both transducer types. The response time was from 10 to 20 s for the QCM sensors and up to 1 minute for the ICP based sensors. The possibility of qualitative identification of poisonous substances in a wide concentration range by means of statistical analysis of the sensor array data is demonstrated.

A Highly Adaptive and Flipping-Time Optimized Piezoelectric Energy Harvesting Interface IC With Synchronized Triple Bias-Flip

This article presents a piezoelectric energy harvesting interface circuit with high adaptability to external inductors, transducer types, and vibration frequencies. High output power can be obtained with the help of triple bias-flip and optimal flipping time control. The triple bias-flip enables both higher efficiency and the use of an inductor with lower volume compared to conventional bias-flip topologies. Besides, owing to the highly adaptive circuit design and reverse current reduction in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant loop, the proposed interface circuit not only automatically adjusts flipping time according to external inductance and piezoelectric transducer, but also reduces the reverse current of the inductor effectively. Also, an active rectifier that can reduce conduction loss of the diode-based rectifier has been implemented. The prototype integrated circuit has been fabricated in 180-nm CMOS technology and the chip area is 0.646 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The measurement results show that the proposed circuit achieves cold start-up without any external power supply, and can work with high efficiency when the external inductor is varying from 0 to 10 mH, transducer capacitance is changing from 20 to 90 nF, and vibration frequency is ranging from 35 to 200 Hz. The measured maximum output power of the proposed design can achieve as high as 473% enhancement to the full-bridge rectifier.

Development of upconversion-NMOFs nanocomposite conjugated with gold nanoparticles for NIR light-triggered combinational chemo-photothermal therapy

Having the unique ability to convert near-infrared (NIR) light to high-energy UV–vis radiation, upconversion nanoparticles are currently used in combinational therapy for the development of cancer theranostic approaches. The present work involves the strategy of a designed system based on gold nanoparticles deposited on upconversion nanoparticles via nanoscale metal–organic frameworks (NMOFs) of MIL-53(Fe). Herein, the NMOFs attached upconversion nanoparticles (UCNPs) are not only capable of loading gold nanoparticles but also carrying anticancer drug 5-fluorouracil for imaging and combined photothermal/chemo therapy for boosted antitumor activity. The developed nanocomposite (UCNPs@MIL-53(Fe)@Au) possesses good stability as well as photothermal conversion ability. The nanocomposite can successfully convert NIR laser light (980 nm, 1.4 W/cm2) into heat, and also promote the release of 5-fluorouracil. This recognizes the synergistic chemo-photothermal treatment of cancer cells. Besides enhancing temperature via energy transfer to gold nanoparticles, upconversion nanoparticles are also utilized as a potential imaging agent. The in-vitro experiments show that the nanocomposite possesses good biocompatibility, and enhanced cellular uptake properties after attaching drug molecules. These findings may deliver a simple and effective way to develop a new type of synergistic chemo-photothermal transducers with high efficiency. We are confident that the nanocomposite (UCNPS@MIL-53(Fe)@Au) could open the door to design a significant multifunctional system for diverse applications in cancer treatment.

Acoustic and Thermal Characterization of Therapeutic Ultrasonic Langevin Transducers under Continuous- and Pulsed Wave Excitations.

We previously conducted an empirical study on Langevin type transducers in medical use by examining the heat effect on porcine tissue. For maximum acoustic output, the transducer was activated by a continuous sinusoidal wave. In this work, pulsed waves with various duty factors were applied to our transducer model in order to examine their effect on functionality. Acoustic power, electro-acoustic conversion efficiency, acoustic pressure, thermal effect on porcine tissue and bovine muscle, and heat generation in the transducer were investigated under various input conditions. For example, the results of applying a continuous wave of 200 VPP and a pulse wave of 70% duty factor with the same amplitude to the transducer were compared. It was found that continuous waves generated 9.79 W of acoustic power, 6.40% energy efficiency, and 24.84 kPa acoustic pressure. In pulsed excitation, the corresponding values were 9.04 W, 8.44%, and 24.7 kPa, respectively. The maximum temperature increases in bovine muscle are reported to be 83.0 °C and 89.5 °C for each waveform, whereas these values were 102.5 °C and 84.5 °C in fatty porcine tissue. Moreover, the heat generation around the transducer was monitored under continuous and pulsed modes and was found to be 51.3 °C and 50.4 °C. This shows that pulsed excitation gives rise to less thermal influence on the transducer. As a result, it is demonstrated that a transducer triggered by pulsed waves improves the energy efficiency and provides sufficient thermal impact on biological tissues by selecting proper electrical excitation types.

CTNI-64. FOCUSED ULTRASOUND MEDIATED BLOOD-BRAIN BARRIER PENETRANCE TO ENABLE CELL-FREE DNA (CFDNA) AS A LIQUID BIOPSY IN RECURRENT PRIMARY BRAIN TUMORS

Abstract The WHO recommends molecular characterization of CNS tumors. (Louis et al., 2021, 2016). However, many patients at diagnosis and recurrence, do not have tissue accessible for genomics. Blood-based liquid biopsy tests, provide a non-invasive means to obtain genomic data. Liquid biopsy tests are widely adopted to avoid side effects related to invasive biopsies in other solid tumors. However, for primary brain tumors, most patients have cfDNA concentrations below the Limit-of-Detection (LOD) of the tests. The primary contributor to low yield is the blood-brain barrier (BBB) which prevents free passage of tumor analytes into the circulatory system. BBB opening mediated by Focused Ultrasound (FUS) oscillation of microbubbles (MB) has led to an increase of tumor-derived circulating biomarkers in pre-clinical models and in human GBM (Zhu et al 2018, Meng et al 2021). Cordance Medical is developing a non-invasive, portable FUS platform that can enable clinic-based BBB opening treatments. The Cordance device utilizes three transducer types, a Type 1 transducer for non-invasive BBB opening localization obtains Doppler images of the Circle-of-Willis through the temporal lobe. The Doppler images align to the existing MRI using CoW as the fiducial. An array of Type 2 transducers for BBB opening to generate sufficient acoustic pressure to safely oscillate MBs to open the BBB. Finally, Type 3 transducers for safety monitoring receive echo signals from the MBs. Signals are analyzed for harmonic content which enables safety monitoring. The primary endpoint, we will be examining the Cordance platform's ability to increase the concentration of circulating biomarkers following a safe BBB opening. We will recruit patients with recurrent GBM. Patients will receive a baseline blood draw, a BBB opening treatment with the Cordance device, followed by a blood draw after the treatment. Liquid biopsy tests to be examined include the MSK ACCESS test and tumor-informed ddPCR MRD test.

Electromechanical response of poly(vinylidenefluoride) thin films under acoustic stimuli

Understanding and controlling the vibration of piezoelectric components induced by oscillating external stimuli is essential to develop smart sensing and energy harvesting devices that convert mechanical energy into electricity. Piezoelectric polymers based on poly(vinylidenefluoride) (PVDF) thin films are amongst the most widely studied materials for flexible sensors and harvesters. Despite the large amount of research on these materials, their electromechanical response under acoustic sound stimuli has not yet been studied in detail. In this work, a thorough investigation on the mechanical vibrations and electrical response of PVDF circular plates of different diameters in response to multiple sound wave frequencies (100 Hz–10 kHz) has been carried out to gain further understanding of the resonance behavior and acousto-electric conversion mechanisms of vibrating PVDF thin films. The work is based on experimental data generated using an integrated piezo-acoustic laser vibrometry system and on a theoretical framework based on the continuum theory of thin plates. The developed model enables the prediction of the resonance frequencies in dependence of the plates’ diameter, and suggests that the electrical voltage generated during vibrations is not solely originating from the piezoelectric properties of the films, but might be affected by additional factors, including the triboelectric effect. The results of this study are expected to have a strong impact on the investigation of piezoelectric vibrating plates and on the development of different types of transducers and energy harvesting devices.

Efficient bubble energy harvesting by promoting pressure potential energy release using helix flow channel

The bubble energy harvesting system can provide in-situ energy supply for the subsea observation equipment through two stages of energy conversion. However, the conversion efficiency of bubble potential energy to fluid energy in the first stage is much lower than that of fluid energy to electrical energy in the second stage, limiting the output capability of the bubble energy harvesting system. Here, a complete energy transfer and conversion model for the subsea bubble energy harvesting is established for the first time. Regardless of the type of transducer used in the system, increasing the released pressure potential energy can substantially improve the efficiency of bubble energy harvesting. Based on this mechanism, we proposed a method to improve the released pressure potential energy and verified the results using a bubble energy harvesting system with a 3D streamline. The flow velocity and fluid volume of the system can be controlled by adjusting the helix angle and cylindrical diameter. Compared with the original system, the fluid pressure potential energy released of a 3D-system with a helix angle of 50 degrees can increase by at least 26%. The output energy density of the 3D-system with a height of 1.6 m can reach 6.6 J/m3, which is 59 times higher than that of the existing technology. This technology can efficiently harvest energy from subsea gas sources, and has the potential to become a long-term in-situ power supply solution for subsea observation networks.

Rotating-Coil Measurement System for Small-Bore-Diameter Magnet Characterization

Rotating-coil measurement systems are widely used to measure the multipolar fields of particle accelerator magnets. This paper presents a rotating-coil measurement system that aims at providing a complete data set for the characterization of quadrupole magnets with small bore diameters (26 mm). The PCB magnetometer design represents a challenging goal for this type of transducer. It is characterized by an aspect ratio 30% higher than the state of the art, imposed by the reduced dimension of the external radius of the rotating shaft and the necessity of covering the entire magnet effective length (500 mm or higher). The system design required a novel design for the mechanical asset, also considering the innovation represented by the commercial carbon fiber tube, housing the PCB magnetometer. Moreover, the measurement system is based primarily on standard and commercially available components, with simplified control and post-processing software applications. The system and its components are cross-calibrated using a stretched-wire system and another rotating-coil system. The measurement precision is established in a measurement campaign performed on a quadrupole magnet characterized by an inner bore diameter of 45 mm.

Application of active acoustic transducers in monitoring and assessment of terrestrial ecosystem health—A review

AbstractUrbanization, agricultural production, natural resource extractions and climate change are global drivers of terrestrial ecosystem degradation and decline in ecosystem health. Assessing vegetation structures provides valuable direct and indirect information on biodiversity and ecosystem health, since plant communities govern terrestrial ecosystem functions and overall biodiversity.A growing body of literature supports the hypothesis that acoustic profiling and characterization of soundscapes may reveal natural patterns and ecosystem responses to environmental disturbances. Although assessments of ecosystem soundscapes are a promising tool for ecological monitoring, the influence of vegetation structure on acoustic indices remains largely unaddressed. An effective non‐invasive approach to monitoring ecosystem health includes use of active acoustic transducers, which convert mechanical/acoustic energy into electrical energy and visa‐versa.This article reviews and discusses possible applications (and also constraints) of active acoustic transducers in monitoring and assessments of terrestrial ecosystem health. Specifically, this article includes a brief introduction to the basic principles of sound and types of active acoustic transducers. Moreover, we provide reviews of common uses of active acoustic transducers in assessing plant structures and plant functional traits.We emphasize that active acoustic transducers can be used to analyse plant characteristics in a remote, scalable, non‐invasive and cost‐effective manner to characterize overall terrestrial ecosystem health. Suggestions and recommendations for future research and management directions that may facilitate applications of acoustic transducers to natural terrestrial landscapes are provided.

Clinical comparison of two automated audiometry procedures.

ObjectiveAutomated pure-tone audiometry has been shown to provide similar hearing threshold estimates to conventional audiometry, but lower correlations were reported at high and low frequencies in audiometric tests than those of manual tests, while the correlations were better in the middle frequencies. In this paper, we used the same equipment and different test procedures for automated testing, and compared the results with manual test results.DesignOne hundred subjects aged 18–36 years were randomly divided into two groups to perform air-conduction pure-tone audiometry (0.25, 0.5, 1, 2, 4, 8 kHz) using the ascending and shortened ascending protocols built-in to the automated audiometer, respectively. Recorded testing time, the total number of responses and the subject’s preference tests were compared with those of manual tests.ResultsSignificant difference was found at 250 Hz regarding the distribution of the absolute difference between the two automated and the manual thresholds. The testing time spend in the ascending method (9.8 ± 1.4 min, mean ± SD) was significantly longer than in the shorted ascending method (5.8 ± 0.9 min). The total numbers of responses of the ascending method (90.5 ± 10.8 times) and shorted ascending method (62.0 ± 11.4 times) were significantly different. Finally, no significant difference was found in preferences between automated and manual procedures.ConclusionThe shorted ascending method can save lots of testing time. The difference between the two automated thresholds at 250 Hz is caused by the different test procedures, and the difference at 8,000 Hz between the automated test and the manual test can be due to the transducer types and allowable differences in calibration.

A new type of dual-branch composite structure-based ultrasonic transducer for microelectronic interconnection and packaging

A new type of composite structure-based ultrasonic transducer was proposed and a complete set of design methods was systematically developed. The transducer adopts a cascaded structure of two tapered ultrasonic horns and a piezoelectric resonator which involves two groups of piezoceramic stacks. The performance test experiments show that the newly proposed transducer can provide dual-directional vibration output either in a separate excitation of one stack or in a simultaneous excitation of two stacks, depending on which it is expected to execute different bonding tasks in the meanwhile. Particularly in a simultaneous excitation pattern, the salient features in the energy superposition and power-sharing enable the transducer to cope with a higher power-required occasion without rising the input power of any branch transducer, avoiding the potential risk of performance deterioration caused by the excessive self-heating of the piezoceramic stack due to a long-term operation. The test results also show that the newly proposed transducer possesses a good deal of flexibility, manifesting the feasibility and effectiveness of the design idea, as well as the relevant design method, and giving the transducer a wider application prospect.

A four-element array design for the implementation of the third-order super-cardioid beam pattern.

This paper presents a practical acoustic source that can implement the third-order super-cardioid beam pattern (SCBP). Based on the product theorem of the array, the third-order dipole beam pattern can be implemented based on the first-order and second-order dipole beam patterns so that a four-element array is designed. In addition, the second-order dipole beam pattern can also be implemented by the same four-element array. Hence, a four-element array is designed to implement the third-order SCBP. Subsequently, the single-sided radiation flextensional transducer-which is a type of low-frequency underwater acoustic transducer-is selected as the array element of the four-element array that is studied and analyzed by means of the finite element method. Finally, a four-element array prototype is fabricated and tested leading to the conclusion that the special four-element array combined with the product theorem provides a practical way for the implementation of the third-order SCBP.

Application of a chord transducer for ultrasonic detection and characterisation of defects in MDPE butt fusion joints

Butt fusion (BF) is the standard method for joining polyethylene (PE) pipes during gas and water pipeline construction. The joints require simple, inexpensive and effective non-destructive testing techniques. Ultrasonic inspection is the most suitable approach; however, joint geometry requires specific configuration of the acoustic beam. In this article, a custom-designed ultrasonic chord transducer optimised for a specific pipe diameter is described. It is demonstrated how variations of sound speed and attenuation in pipe material with temperature variations affects the operation of this type of transducer. A variety of common defects, including cold fusion, dust, dirt, grass contamination, voids, etc, are simulated inside the joint and used for technique development. Analysis of an A-scan produced in pitch-catch mode allows for the evaluation of joint quality and the classification of defect type.

Algorithms for Probabilistic and Stochastic Subsequential Failure Transducers

This paper introduces a framework for building probabilistic models with subsequential failure transducers. We first show how various types of subsequential transducers commonly used in natural language processing are represented by conditional probabilistic subsequential transducers and probabilistic subsequential failure transducers. Afterwards, we introduce efficient algorithms for composition of conditional probabilistic subsequential transducers with probabilistic subsequential failure transducers and canonization (weight-pushing) of probabilistic subsequential failure transducers. Those algorithms are applicable to many tasks for representing probabilistic models. One such task is the construction of the [Formula: see text] weighted transducer used in speech recognition which we describe in detail. At the end, a comparison between the presented [Formula: see text] failure weighted transducer and the standard [Formula: see text] weighted transducer along with empirical results for HMM-based speech recognition decoding reveal the competitiveness of the presented constructions.