Types Of Transducers Research Articles

Pressure sensing properties for the dielectric layer of graphene/silicone rubber‐based magnetorheological elastomer

AbstractIn order to expand the application of magnetorheological elastomers (MREs) in the field of sensor technology and improve their dielectric properties, a type of MRE with modified graphene, graphene/silicone rubber‐based magnetorheological elastomer (GR/RTV‐MRE), is proposed and its dielectric sensing properties were investigated. A model for calculating the relative permittivity of MRE was developed and combined with VASP software simulation to obtain the relative permittivity of GR/RTV‐MRE with different graphene contents. Combining the silicone rubber matrix with 30 vol% micro‐sized (ca 3.5 μm) spherical carbonyl iron particles, GR/RTV‐MRE samples with different graphene contents were prepared and tested for their relative permittivity. There is an error of approximate 7% between the test results and the simulation results, and the relative permittivity of GR/RTV‐MRE with a graphene content of 3 vol% reaches a maximum value of 35.400. An experimental platform for compressive properties was constructed and the compressive modulus of GR/RTV‐MRE with a graphene content of 3 vol% was tested under a magnetic field of 0–1 T. The results show that the modulus of compressibility is positively correlated with the magnetic field intensity in the range 0–0.9 T, up to 3.98 MPa, and is almost constant in the range 0.9–1 T. GR/RTV‐MRE with a graphene content of 3 vol% was used as the dielectric of a capacitive type transducer. The sensitivity of the capacitive sensor was measured to be 0.07 kPa−1 with a linear fitting of 99.6%. It is shown that GR/RTV‐MRE with 3 vol% graphene has good dielectric sensing capability. © 2022 Society of Industrial Chemistry.

Ultrasound Imaging Acquisition Procedures for Evaluating the First Metatarsophalangeal Joint: A Scoping Review.

The aim of this scoping review was to investigate ultrasound imaging (USI) acquisition procedures and guidelines used to assess the first metatarsophalangeal joint (MTPJ). MEDLINE, CINAHL, AMED and SPORTDiscus were systematically searched in May 2021. Studies were included if they used grey-scale USI or power Doppler and reported a USI procedure to assess the first MTPJ. Screening and data extraction were performed by two independent assessors. The scoping review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for scoping reviews (PRISMA-ScR). A total of 403 citations were identified for screening, with 36 articles included in the final analysis. There was wide variation in USI acquisition procedures used to evaluate the first MTPJ. Inconsistencies in reporting may be attributable to the number of elements the USI acquisition procedure encompasses, which include the model of the USI device, the type of transducer, USI modalities and settings, patient position, transducer orientation, surfaces scanned and the scanning technique used. The review found inconsistencies against international guidelines and limited implementation of consensus-based recommendations to guide image acquisition. Current guidelines require further refinement of anatomical reference points to establish a standardised USI acquisition procedure, subsequently improving interpretability and reproducibility between USI studies that evaluate the first MTPJ.

Ultrasound for the diagnosis of shoulder dislocation and reduction: A systematic review and meta‐analysis

AbstractBackgroundShoulder dislocations are a common injury prompting presentation to the emergency department. Point‐of‐care ultrasound (POCUS) is a diagnostic tool for shoulder dislocations, which has the potential to reduce time to diagnosis and reduction, radiation exposure, and health care costs. This systematic review sought to evaluate the diagnostic accuracy of POCUS for diagnosing shoulder dislocations.MethodsWe searched PubMed, Scopus, CINAHL, LILACS, the Cochrane databases, Google Scholar, and bibliographies of selected articles for all prospective and randomized controlled trials evaluating the diagnostic accuracy of POCUS for identifying shoulder dislocations. We dual‐extracted data into a predefined worksheet and performed quality analysis using the QUADAS‐2 tool. We performed a meta‐analysis with subgroup analyses by technique and transducer type. As a secondary outcome, we assessed the diagnostic accuracy of identifying associated fractures.ResultsTen studies met our inclusion criteria, comprising 1,836 assessments with 636 dislocations (34.6%). Overall, POCUS was 100% (95% confidence interval [CI], 85.6%–100%) sensitive and 100% (95% CI, 79.4%–100%) specific for the diagnosis of shoulder dislocation with a LR+ of 11,254.8 (95% CI, 3.9–3.3e7) and a LR− of <0.1 (95% CI, < 0.1–0.2). When compared with the anterior/lateral technique, the posterior technique had greater sensitivity but no difference in specificity. There was no difference between transducer types. POCUS was also 96.8% (95% CI, 92.6%–98.7%) sensitive and 99.7% (95% CI, 92.5%–100%) specific for the diagnosis of associated fractures.ConclusionsPOCUS is a sensitive and specific tool for the rapid identification of shoulder dislocations and reductions, as well as for the detection of associated fractures. POCUS should be considered as an alternate diagnostic tool for the diagnosis and management of shoulder dislocations.

Effects of Accelerated Aging on the Performance of Low-Cost Ultrasonic Sensors Used for Public Lighting and Mobility Management in Smart Cities.

In the field of Smart Cities, especially for Smart Street Lighting and Smart Mobility, the use of low-cost devices is considered an advantageous solution due to their easy availability, cost reduction and, consequently, technological and methodological development. However, this type of transducers shows many critical issues, e.g., in metrological and reliability terms, which can significantly compromise their functionality and safety. Such issue has a large relevance when temperature and humidity are cause of a rapid aging of sensors. The aim of this work is to evaluate the effects of accelerated aging in extreme climatic conditions on the performance of a control system, based on a low-cost ultrasonic distance sensor, for public-lighting management in Smart Cities. The presented architecture allows for the detection of vehicles, pedestrians and small animals and contains a dedicated algorithm, developed in an Edge/Cloud environment, that is able to display the acquired measurements to users connected on the web. The obtained results highlight that the effect of accelerated aging is to significantly reduce the linearity of the calibration curve of the sensor and, moreover, to exponentially increase the number of outliers and invalid measurements. These limitations can be overcome by developing an appropriate self-calibration strategy.

Machine learning approach to optimization of parameters for impedance measurements of Quartz Crystal Microbalance to improve limit of detection

Impedance spectroscopy allows real time monitoring of fundamental resonance frequency and harmonics of AT cut Quartz Crystal Microbalance (QCM) biosensors. Acquisition of accurate and high resolution spectroscopic data requires optimization of parameters, which is rarely performed as it requires an excessive number of experiments. In this work, machine learning clustering and classification algorithms are applied in an attempt to minimize the number of experiments by designating a small representative subset of chosen values of parameters, while preserving the variation of those values. Our results indicated it is possible to reduce the number of experiments required by more than 10 fold. The constructed model has both an unsupervised clustering part (k-means algorithm) and a supervised classification part (Support Vector Machine algorithm), working independently. From those two different approaches 83% compatibility is obtained. Such optimization can improve limit of detection (LOD) of glycerol concentrations by a factor of 12 using a QCM with a fundamental resonance frequency of 10 MHz. This approach can be applied not only to biosensors but also to chemical sensors involving resonance frequency monitoring by means of impedance spectroscopy, and has the potential to be expanded to systems with different transducer types, monitoring resonance by other means.

Polymer Microtip on a Multimode Optical Fiber as a Threshold Volatile Organic Compounds Sensor.

Polymer microtips are 3D microstructures manufactured on the end face of an optical fiber by using the photopolymerization process. Such micro-optic elements made on a multi-mode optical fiber were previously tested as a transducer of refractive index sensor. These studies were an inspiration to investigate the possibility of using this type of transducer to measure the presence of volatile organic compounds in the air. The experimental results of microtips polymerized with UV and VIS were reported. It was possible to detect the presence of five different volatile compounds in the air due to the sensitivity of the transducer to the refractive indices changes. These changes were induced by the vapors condensed on the microtip surface. The measured time responses have shown that the return loss decreases rapidly as the microtip is inserted inside a glass vial filled with the tested compound. Moreover, correlations between calculated dynamic ranges and refractive indices and volumes of the volatile compounds inside the vials were negligible. Therefore, this type of sensor can be categorized as a condensed material threshold sensor. This sensor can be used in warning systems for monitoring leakages of pipelines carrying volatile chemicals.

Acoustic Emission Damage Detection during Three-Point Bend Testing of Short Glass Fiber Reinforced Composite Panels: Integrity Assessment

In this study, an acoustic emission (AE) technique was used as a passive non-destructive tool to detect the damage progress in short glass fiber-reinforced composite panels. AE detection was conducted during three-point bend tests, thus illustrating the flexural damage accumulation for composite panels with different sizes and fiber volume content. To demonstrate the universality of the employed integrity assessment methodology, AE data was detected using different timing parameters and two different transducer types, i.e., medium-band and wide-band frequency sensors. The AE waveform classification presented in this study is based on peak frequency distributions. Frequency bands that are associated with certain failure mechanisms, including matrix micro-cracking, fiber debonding, delamination, and fiber breakage, were obtained from the technical literature. Through this investigation, the concept of cumulative signal strength (CSS) and cumulative rise time versus peak amplitude ratio (CRA) as AE output parameters are shown to facilitate integrity assessment for the employed complex composite material system. Significant jumps in CSS and CRA curves could be correlated to critical strain levels and distinct damage events in the composite panels subjected to flexural loading.

System Invariant Method for Ultrasonic Flaw Classification in Weldments Using Residual Neural Network

The industrial use of ultrasonic flaw classification using neural networks in weldments must overcome many challenges. A major constraint is the use of numerous systems, including a combination of transducers and equipment. This causes high complexity in the datasets used in the training of neural networks, which decreases performance. In this study, the performance of a neural network was enhanced using signal processing on an ultrasonic weldment flaw dataset to achieve system invariance. The dataset contained 5839 ultrasonic flaw signals collected by various types of transducers connected to KrautKramer USN60. Every signal in the dataset was from 45 FlawTech/Sonaspection weldment specimens with five types of flaw: crack, lack of fusion, slag inclusion, porosity, and incomplete penetration. The neural network used in this study is a residual neural network with 19 layers. The performance evaluation of the same network structure showed that the original database can achieve 62.17% ± 4.13% accuracy, and that the invariant database using the system invariant method can achieve 91.45% ± 1.77% accuracy. The results demonstrate that using a system invariant method for ultrasonic flaw classification in weldments can improve the performance of a neural network with a highly complex dataset.

Study on the acoustic field characteristics of OPCM focusing transducer

The advanced orthotropic piezoelectric composite material (OPCM) sensor can be used in structural health monitoring with a highly sensitive performance. In order to reduce the interference of lateral reflected waves and obtain the reflected wave signal with wide frequency bandwidth and high focusing energy, a new type of OPCM focusing transducer was studied based on the previous research of OPCM. Compared with the PZT transducer, the superiority and the acoustic field characteristics of the OPCM focusing transducer are studied by simulation, and the stress comparison results are verified by experiments. It is shown that the blind area of the focusing transducer in engineering structure detection is about 1.5 mm from the detection surface, which greatly increases the ease of obtaining reflected wave signals with high energy and high signal-to-noise ratio in engineering structure damage detection.

Factors Influencing the Purchase Rate of Cartilage Conduction Hearing Aids.

Innovated hearing aids (HAs), termed cartilage conduction hearing aids (CC-HAs), show good performance in patients with closed ears and continuous otorrhea. However, factors other than the ear condition that influence the purchase rate of CC-HAs remain unclear. To identify the factors that influence the purchase rate of CC-HAs. A correlational study. A total of 249 patients were enrolled. The patients' demographics, clinical characteristics, outcomes, and CC-HA transducer types were compared. The data were analyzed for six groups classified based on the ear condition. In the unilateral closed-ear group, the purchase cases were significantly younger than the nonpurchase cases (p < 0.05). Regarding the outcomes in the bilateral closed-ear group, the purchase cases showed significantly better-aided thresholds at 0.25 and 0.5 kHz than the nonpurchase cases. No significant differences in the functional gains and speech recognition scores were found between purchase and nonpurchase cases in all six groups. Regarding the transducer type, the continued-use rate of the simple transducer type was significantly lower in the bilateral chronic continuous otorrhea, bilateral open, and unilateral open groups. In the closed ears, no remarkable negative factors were found. Transducer type had a significant influence on the continued-use rate in the nonclosed ears including the ears with chronic continuous otorrhea, although the purchase rate of CC-HAs in the bilateral chronic continuous otorrhea group was comparable to the closed ears.

Influence of the type of acoustic transducer in pure-tone audiometry.

To compare the air-conduction hearing thresholds obtained with different acoustic transducers and verify the users' preferences regarding them. This is a cross-sectional, analytical, observational study with 26 participants aged 18 to 30 years, with normal hearing and no history of exposure to high sound pressure levels or complaints of tinnitus at the time of the assessment. We surveyed their medical history and performed meatoscopy, pure-tone threshold audiometry, speech audiometry, and acoustic immittance. The auditory thresholds were surveyed twice, each time with a different type of acoustic transducer: insert (E-A-RTONE) and circumaural earphones (HDA200). The assessments were performed in a random order, with 5-minute intervals. In the end, we asked the participants which earphones they found more comfortable in the tests. The data were submitted to nonparametric statistical analysis. Assessing the medians in the auditory threshold survey, the circumaural earphones obtained better results at 250, 500, 2000, and 6000 Hz, while the insert earphones were better at 3000 and 4000 Hz; there were no statistical differences at 1000 and 8000 Hz. The circumaural was elected the most comfortable earphone. The circumaural earphones had better auditory thresholds at 250, 500, 2000, and 6000 Hz than the insert earphones and were reported by the patients as the most comfortable type of transducer.

The Impact of Transducer Selection on the Acceptable Noise Level

The aim of this study was to assess the impact of transducer (loudspeaker, supra-aural headphones, and insert earphones) selection on the acceptable noise level (ANL). Thirty young adults with normal hearing who reported difficulty with background noise served as participants. A repeated-measures experimental design was employed. Most comfortable listening level (MCL) and background noise level (BNL) were measured for all participants using three transducers (loudspeaker, supra-aural headphones, and insert earphones). ANL was computed as the difference between the mean MCL and the mean BNL. Analytical statistics revealed that ANL did not differ due to the transducer used. However, there were statistically significant differences found for MCL and BNL across transducers. Results of this study indicate that ANL is not vulnerable to the selection of transducer and that ANLs can be compared across transducer types. Researchers should cautiously interpret findings across studies when discussing the base measures of MCL and BNL as these may be influenced slightly by transducer selection.

Теоретичне обґрунтування типу променевих перетворювачів при ідентифікації зернового потоку

The article is devoted to the theoretical substantiation of the type of beam converters in the identification of grain flow in planters. The working conditions of beam transducers in the process of sowing grain crops, types and characteristics of such transducers are considered. It is shown that the best characteristics are possessed by optocouples created on the basis of independent sources and receivers of infrared radiation in the form of silicon diodes operating in the range of 0.75...1.1 μm. This publication is aimed at the implementation of means of control during the sowing of grain crops, its topic is relevant. It is directed to the implementation of the program "Technical means of the new generation for agricultural production", included in the list of State targeted scientific and scientific and technical programs, defined by the law of Ukraine "On priority areas of development of science and technology". The publication examines the theoretical justification of the type of beam transducers in devices for identifying the grain flow formed by seeding devices of seed drills, in order to increase their resolution and quality of registration of discrete objects in the flow. As a result of the analysis of the conditions for identifying the grain flow when sowing grain crops, we come to the conclusion that it is advisable to use optocouplers from separate elements "radiation source"-"radiation receiver" of the infrared spectrum that work in the range of as beam converters. Based on the fact that the registration device includes dozens of discrete optocouplers, silicon light and photodiodes should be used as IR emitters and receivers, as they are the cheapest, simpler in circuit connection than photo transistors and sufficient to obtain the necessary resolution when registering and recognizing the flow of grains.

Fundamentals of Biosensors and Detection Methods.

Biosensors have a great impact on our society to enhance the life quality, playing an important role in the development of Point-of-Care (POC) technologies for rapid diagnostics, and monitoring of disease progression. COVID-19 rapidantigen tests, home pregnancy tests, and glucose monitoring sensors represent three examples of successful biosensor POC devices. Biosensors have extensivelybeen used in applications related to the control of diseases, food quality and safety, and environment quality. They can provide great specificity and portability at significantly reduced costs. In this chapter are described the fundamentals of biosensors including the working principles, general configurations, performance factors, and their classifications according to the type of bioreceptors and transducers. It is also briefly illustrated the general strategies applied to immobilize biorecognition elements on the transducer surface for the construction of biosensors. Moreover, the principal detection methods used in biosensors are described, giving special emphasis on optical, electrochemical, and mass-based methods. Finally, the challenges for biosensing in real applications are addressed at the end of this chapter.

ULTRASOUND IMAGING OF THE SPLEEN, STOMACH, LIVER, KIDNEYS, BLADDER, AND PROSTATE IN PIGLETS (Sus scrofa domestica)

This study aims to describe ultrasonographic imaging of the spleen, stomach, liver, kidney, bladder, and prostate in piglets (Sus scrofa domestica). Ultrasonography was performed on six male piglets aged 1 month with a body weight of 4-8 kg. Ultrasonography of the spleen, stomach, liver, urinary bladder, and prostate was observed in the dorsal-recumbency position, and the kidney was observed in the lateral-recumbency position. The ultrasound examination used the Chison EBit 60, which is a linear type transducer with a frequency of 9 MHz, transverse and sagittal positions, and a gain of about 55-80. Ultrasonography of the spleen showed that the shape of the spleen head varied in each individual. The results of gastric ultrasonography showed the gastric lining clearly and the similarity of the position, shape, structure, echogenicity, and size of the stomach. The results of liver ultrasonography showed that the echogenicity of the liver tended to be hyperechoic, the kidneys were hyperechoic, and the bladder was hypoechoic due to the use of improper gain. The average length of the right kidney was 4.73±0.50 cm and the left kidney was 4.08±0.26 cm. The bladder wall thickness was 1.3±0.31 mm. Imaging of the bladder showed changes in wall size and echogenicity. Prostate ultrasound results obtained an average length of 2.68±0.45 cm, width 1.69±0.35 cm. The results of this study can be used as a reference for normal data on organ position, organ structure, and organ echogenicity of the spleen, stomach, liver, kidney, bladder, and prostate in piglets.

Microfluidic-Based Oxygen (O2) Sensors for On-Chip Monitoring of Cell, Tissue and Organ Metabolism.

Oxygen (O2) quantification is essential for assessing cell metabolism, and its consumption in cell culture is an important indicator of cell viability. Recent advances in microfluidics have made O2 sensing a crucial feature for organ-on-chip (OOC) devices for various biomedical applications. OOC O2 sensors can be categorized, based on their transducer type, into two main groups, optical and electrochemical. In this review, we provide an overview of on-chip O2 sensors integrated with the OOC devices and evaluate their advantages and disadvantages. Recent innovations in optical O2 sensors integrated with OOCs are discussed in four main categories: (i) basic luminescence-based sensors; (ii) microparticle-based sensors; (iii) nano-enabled sensors; and (iv) commercial probes and portable devices. Furthermore, we discuss recent advancements in electrochemical sensors in five main categories: (i) novel configurations in Clark-type sensors; (ii) novel materials (e.g., polymers, O2 scavenging and passivation materials); (iii) nano-enabled electrochemical sensors; (iv) novel designs and fabrication techniques; and (v) commercial and portable electrochemical readouts. Together, this review provides a comprehensive overview of the current advances in the design, fabrication and application of optical and electrochemical O2 sensors.

Practical review on photoacoustic computed tomography using curved ultrasound array transducer.

Photoacoustic computed tomography (PACT) has become a promising imaging modality from laboratory to clinical research. Of many components of PACT system, the ultrasound (US) array transducer is an essential device to simultaneously receive photoacoustic (PA) signals from several directions in a parallel manner. Many research groups and companies have developed various types of US array transducers while accounting the properties of the PA waves to achieve better image quality, deeper imaging depth, faster imaging speed, and a wider field of view. In this review, we present the implementation and application of the state-of-the-art PACT systems using several types of curved US arrays: arc-shaped, ring-shaped, and hemispherical array transducers. Furthermore, we discuss the current limitations of PACT and also potential future directions for enhancing them.

Coercive force of double layer ferromagnetic materials

Peculiarities of the coercive force (CF) measuring of inhomogeneous ferromagnetic materials, in particular layered ones, are considered. The concept of effective CF of layered ferromagnetic materials is introduced. The analysis of the magnetic fluxes distribution in a double layer ferro-magnetic material during its reversal magnetization by an attachable transducer with a U-shaped core made of soft magnetic material is carried out. An analytical expression of the effective CF for such class of materials for the case of the same layers’ thickness and linear approximation of their demagnetization curves is obtained. It was found that the effective CF of a double layer ferromagnetic material is determined not only by the CF of its individual layers, but also by the values of their residual induction. Experimental verification of the obtained results was performed on experimental samples, which were collected from steel 08kp (sample # 1) and steel St3 (sample # 2) plates. Each of the samples was a stack of 6 plates each measuring 87×50×1 mm. With tight compression of the plates and complete elimination of the gaps between them, these samples can be considered as single layer ferromagnetic structures with a thickness of 6 mm. To model a double layer ferromagnetic material with the same layer thickness, sample № 3 was used. Its the upper part consisted of the three steel 08kp plates and the lower part – of the three steel St3 plates. To measure the magnetic parameters of these samples the KRM-Ts-MA type magnetic analyzer was used. The device permit to measure the CF, residual induction and other parameters of the hysteresis loops of ferromagnetic materials in the closed magnetic circuit by attachable type transducers with U-shaped core. The transducer used with the magnetic analyzer during the experiments had poles with an area of 16×32 mm and the distance between the edges of the poles: inner – 32 mm, outer – 64 mm. It is shown that the discrepancy between the calculated value of the effective CF of the double layer ferromagnetic material (sample # 3) from steel 08kp and St3 according to the obtained expression and the measurement results is about 3%. This confirms the adequacy of the proposed model of reversal magnetization of double layer ferromagnetic material and the correctness of analytical calculations.

Pulsed-laser source characterization in laboratory seismic experiments

The present study aimed to characterize the properties of a laser-generated seismic source for laboratory-scale geophysical experiments. This consisted of generating seismic waves in aluminum blocks and a carbonate core via pulsed-laser impacts and measuring the wave-field displacement via laser vibrometry. The experimental data were quantitatively compared to both theoretical predictions and 2D/3D numerical simulations using a finite element method. Two well-known and distinct physical mechanisms of seismic wave generation via pulsed-laser were identified and characterized accordingly: a thermoelastic regime for which the incident laser power was relatively weak, and an ablation regime at higher incident powers. The radiation patterns of the pulsed-laser seismic source in both regimes were experimentally measured and compared with that of a typical ultrasonic transducer. This study showed that this point-like, contact-free, reproducible, simple-to-use laser-generated seismic source was an attractive alternative to piezoelectric sources for laboratory seismic experiments, especially those concerning small scale, sub-meter measurements.

Symmetric Reflector Ultrasonic Transducer Modeling and Characterization: Role of the Matching Layer on Electroacoustic Performance.

Symmetric reflector ultrasonic transducers (SRUTs) are a new type of ultrasonic transducer that take advantage of the ultrasonic wave emitted on the rear face of the active element. In this work, the electroacoustic modeling and characterization of such a structure is reported. Using the well-known Krimholtz, Leedom, et Matthaei (KLM) model, the electroacoustic response of a SRUT based on a piezoelectric ceramic with one matching layer is calculated. Simulations show that the optimal acoustic impedance of the matching layer should be lower than for conventional transducers, leading to a relative bandwidth of approximately 50%. The characterization of such a transducer based on a piezoceramic plate has been carried out. Bandwidth and sensitivity are reported. They are found to be close to the simulation results and demonstrate that these new types of transducers need to be designed according to new rules compared to conventional ones.