Use Of Transducers Research Articles

AIUM Official Statement: Guidelines for Cleaning and Preparing External- and Internal-Use Ultrasound Transducers and Equipment Between Patients as Well as Safe Handling and Use of Ultrasound Coupling Gel.

AIUM Official Statement: Guidelines for Cleaning and Preparing External- and Internal-Use Ultrasound Transducers and Equipment Between Patients as Well as Safe Handling and Use of Ultrasound Coupling Gel.

Advanced Foot step power generation system for mobile charging

The major focus of this study is the generation of electric power from people’s footsteps and the pressure applied when walking. “Advanced Foot Step Power Generation System” refers to the mechanical power transformation into electrical power as a result of the pressure generated by the footstep and the use of transducers. The power-producing floor generates power, which is essentially the conversion of kinetic energy into electrical energy. Today’s electricity demand is growing, and existing power generation sources are unable to meet this worldwide challenge. The fundamental issue of the energy crisis is the demand and supply imbalance. Although it will not be enough to meet the world’s overwhelming need for electrical energy, it will be able to transform and reduce dependency on traditional methods of generating electricity. It can be implemented on roadside footpaths, parks and jogging tracks, as well as many other public places, such as airports, and will have a significant impact on electrical power generation.

3D Ultrasound: Visualization of Volumetric Data

This article continues a previously published review, “3D ultrasound: Current state, emerging trends and technologies,” which was the first part in a cycle addressing 3D/4D ultrasound technologies. The first part explained the basic mechanisms for obtaining three-dimensional ultrasound images and considered the physical basis, advantages, and drawbacks associated with the use of transducers and the main methods of volumetric scanning. The present article describes the capabilities of the state-of-the-art diagnostic ultrasound scanners to visualize 3D/4D data.

Influence of Load and Transducer Bandwidth on the Repeatability of In Vivo Tendon Stiffness Evaluation Using Shear Wave Elastography

Objective: To determine how different examination protocols with the use of transducers, of different bandwidths, and applied with varied tension to tendons would influence the sonographic study results. Methods: Thirty-one participants were divided into two groups, with one subject used for theoretical investigation (A) and the remaining participants (B = 30) forming the study cohort. Both sets of participants were examined with three different transducers (SL10–3, SL15–4, and SL18–7) as well as with variable loading on the Achilles tendon (relaxed, tensed, and loaded). The resulting coverage of the color map provided qualitative tendon stiffness and quantitative tendon stiffness values. Results: The estimated mean coverage extent, using elastographic color maps, produced by the three transducers was 98%, 98%, and 99%, respectively, in the relaxed state. Likewise, in the tensed state, mean coverage was 85%, 82%, and 77% in group A and 91%, 78%, and 71% in group B, respectively. Examining tendons that were loaded, the mean coverage was 68%, 42%, and 41%, respectively. The quantitative relaxed mean tendon elasticity values were 323, 366, and 393 kPa, respectively, in group A. Likewise, the relaxed mean values were 329, 341, and 358 kPa, respectively, in group B. The quantitative tensed mean tendon elasticity values were 413, 460, and 426 kPa, respectively, in group A. Likewise the tensed mean values were 412, 440, and 436 kPa, respectively, in group B. Conclusions: Varying the tendon loading significantly influenced the color map coverage, which governs the most reliable quantitative measurements on relaxed tendons. The best color map coverage was achieved using the transducer with the lowest frequency, regardless of the tension applied.

Internal Positioning System for Cardiotocograph (CTG) Transducers at Mackay Base Hospital

Abstract Cardiotocographs (CTG) are essential pieces of medical equipment that assist in the birth suite and during maternity surveillance. These devices require the use of transducers that communicate wirelessly to the CTG and enable an expectant mother to have water births. When the CTG transducers are lost, or misplaced, there is no system that can locate the expensive accessories. Thus, necessitates the need to develop an Internal Positioning System at Mackay Base Hospital. The device that was proposed to be used in the system is an Xbee S68© Wi-Fi RF module designed by DIGI International. This device is capable of communicating to Access Points for the purposes of location tracking only. It was successfully demonstrated on a small home network that the Xbee device was able to transmit/ receive data from characteristic packet signatures which was captured using Wireshark©. Furthermore, to ensure the device can be aligned with IP67 rating an enclosure was designed to enable the device to be immersed in water. Overall it was ascertained that the device is able to connect on a small network, which can be easily applied on a larger WLAN, in addition to all the project outcomes of an Engineering style report was demonstrated.

Recent Advances in Cast Iron Structure and Properties Ultrasonic Testing and Flaw Detection

The advantage of ultrasonic testing of iron castings prior to destructive control consists of an impressive reduction in time and costs, as well as the ability to assess the quality of the metal anywhere on the castings. According to the acoustic characteristics of cast iron it is possible to determine the form of graphite in it and its strength. The presence of chill in the metallic base and the thickness of the chilled layer is also determined by ultrasonic method. The use of electronic signal processing allows to distinguish it from high structural noise, which makes possible the testing of cast iron for a thickness of several meters. The use of transducers with phased array is the basis of the flaw detection of containers for nuclear waste from cast iron with globular graphite with a thickness of 500 mm.

Automated Audiometry: A Review of the Implementation and Evaluation Methods.

ObjectivesAutomated audiometry provides an opportunity to do audiometry when there is no direct access to a clinical audiologist. This approach will help to use hearing services and resources efficiently. The purpose of this study was to review studies related to automated audiometry by focusing on the implementation of an audiometer, the use of transducers and evaluation methods.MethodsThis review study was conducted in 2017. The papers related to the design and implementation of automated audiometry were searched in the following databases: Science Direct, Web of Science, PubMed, and Scopus. The time frame for the papers was between January 1, 2010 and August 31, 2017. Initially, 143 papers were found, and after screening, the number of papers was reduced to 16.ResultsThe findings showed that the implementation methods were categorized into the use of software (7 papers), hardware (3 papers) and smartphones/tablets (6 papers). The used transducers were a variety of earphones and bone vibrators. Different evaluation methods were used to evaluate the accuracy and the reliability of the diagnoses. However, in most studies, no significant difference was found between automated and traditional audiometry.ConclusionsIt seems that automated audiometry produces the same results compared with traditional audiometry. However, the main advantages of this method; namely, saving costs and increased accessibility to hearing services, can lead to a faster diagnosis of hearing impairment, especially in poor areas.

Novel nondestructive evaluation transducer for imaging of low-impedance targets

Piezoelectric materials, such as lead zirconate titanate, display high electromechanical coupling, low internal losses, and exceptional environmental durability making them the material of choice for acoustic imaging transducers. Traditionally, piezoelectric transducers are actuated in the thickness-extension mode and they often make use of “matching” films to improve the signal transmissibility into lower acoustic impedance targets. In this article, we propose the use of transducers coupled to a structure in a direction orthogonal to the resonating plane. An analytical solution for the electromechanical behavior of a piezoelectric plate coupled transversely is derived. The analytical model shows that when resonated transversely, a transducer could display significantly lower effective acoustic impedance compared to transducers actuated in the thickness-extension mode. This feature eliminates the need for the matching films, hence helping reducing manufacturing costs. General guidelines on how to optimize the design of the proposed transducer for impedance imaging are also given. Finally, this article shows one example of how using a lead zirconate titanate transducer resonated transversely can reliably detect matrix cracking in fiberglass composite plates.

English

In this work, we study the propagation of the plane waves in a solid medium (Aluminium) which contains a periodic two-dimensional (2D) array of cylindrical inclusions using a multiple scattering theory. The aim of this study is to validate the experience of certain theoretical predictions such as the frequential positions of the stop-bands and their widths like their evolution according to the geometrical characteristics of the 2D array. The cavities are excited in normal incidence. Measurements are taken in the case of the empty cavities. The acquisitions of all the transmission and reflection temporal signals are obtained by the use of transducers of contact. All the recorded signals are subjected to a signal processing (FFT, normalization).   Key words: Multiple scattering theory/periodic distributions of inclusions/stop-bands/two-dimensional (2D) array.

Influence of the Section Plane Position on the Performance of Power Ultrasonic Transducer

In this paper, five kinds of power ultrasonic transducers with different section plane positions are designed and the shapes of the transducers are straight. The different section plane position changes with the length l2 of front cover. That is to say, the longer l2 is, the more front the position of the section is. The experiment indicates the great influence of the section plane position on the transducer performance.With the increase of the length of the front cover, the dynamic resistance reduces gradually, and the resonance frequency and the anti-resonance frequency also reduce. Under this condition, the anti-resonance frequency declines more sharply, and the mechanical quality factor increases gradually, but the effective mechanical and electrical coupling coefficient reduces gradually. The transducer has different measure targets in different situations. Therefore, different parameters may be primordially considered to be designed according to the actual use of the transducer in this paper. This provides the reference for manufacture and use of transducers.

Mechanical testing of bones: the positive synergy of finite–element models andin vitroexperiments

Bone biomechanics have been extensively investigated in the past both with in vitro experiments and numerical models. In most cases either approach is chosen, without exploiting synergies. Both experiments and numerical models suffer from limitations relative to their accuracy and their respective fields of application. In vitro experiments can improve numerical models by: (i) preliminarily identifying the most relevant failure scenarios; (ii) improving the model identification with experimentally measured material properties; (iii) improving the model identification with accurately measured actual boundary conditions; and (iv) providing quantitative validation based on mechanical properties (strain, displacements) directly measured from physical specimens being tested in parallel with the modelling activity. Likewise, numerical models can improve in vitro experiments by: (i) identifying the most relevant loading configurations among a number of motor tasks that cannot be replicated in vitro; (ii) identifying acceptable simplifications for the in vitro simulation; (iii) optimizing the use of transducers to minimize errors and provide measurements at the most relevant locations; and (iv) exploring a variety of different conditions (material properties, interface, etc.) that would require enormous experimental effort. By reporting an example of successful investigation of the femur, we show how a combination of numerical modelling and controlled experiments within the same research team can be designed to create a virtuous circle where models are used to improve experiments, experiments are used to improve models and their combination synergistically provides more detailed and more reliable results than can be achieved with either approach singularly.

The effects of transducers on the time reversal process in solids

Every experimental implementation of Time Reversal (TR) involves the use of transducers to convert wave motion, whether mechanical or acoustical, into electrical signals, and vice versa. Practical considerations of transducers are not included in the basic theory of time reversal, which is based on idealized point-like sources. These considerations include temporal ring down at a narrowband transducer resonance, the finite size of the transducer giving rise to directivity, and the impedance contrast between the transducer and the medium. The effects of these considerations on the TR process will be characterized by presenting data from various TR experiments.

Visualization of the uterine fundus in intrauterine sonography

Intrauterine sonography (hysterosonography) is useful for visualising malignant processes in the myometrium. Since normally no sound-wave source is available for beaming the sound waves in strictly anterograde direction, the authors examined which sections of the fundus of the uterus cannot be assessed, and discussed the possibilities of reducing the area and also the importance of the inaccessible region. It was found that normally a satisfactory assessment would be possible in clinical routine even in the region of the fundus by the combined shifting of the geometrical axis of the sound waves and the use of transducers from which the sound waves emanate in anterograde direction at an angle of 135 degrees.

Apêndice atrial esquerdo: imagem ecocardiográfica transtorácica tridimensional em tempo real

1-4 . This fact becomes especially relevant when anatomical observation translates into prognostic clinical implications, such as in the identification of images of thrombi in the left atrium or left atrial appendage. In most clinical situations, the investigation of intra-atrial images of thrombi with the use of two-dimensional transthoracic echocardiography does not allow anatomical information reliable enough for a diagnostic definition. Use of multiplane bidimensional transesophagic echocardiography enabled additional diagnostic information for discrimination of intra-atrial masses caused by the use of transducers with a greater ultrasound emission frequency, at a greater proximity to the structure of interest, providing images with a better quality of structural definition. Nevertheless, this semi-invasive echocardiographic modality does not yet allow structural from all anatomic planes of observation (a primary limitation for structural identification based on frontal and transversal cardiac planes, with observation point in atrioventricular, pulmonary, and aortic valve rings). Real-time three-dimensional transthoracic echocardiography is an advancement in anatomical analysis because it allows a rotation of heart structures based on three primary planes of structural definition (infero-superior plane, mid-lateral plane, and depth or elevation plane), as well as a structural composition based on the analysis of composite planes or diagonal planes. Image acquisition is made in real-time, and the final image may be obtained by the projection of interest to the clinician or surgeon. In the case shown, we observe the two-dimensional transthoracic echocardiographic analysis of the left atrial appendage (Figure 1), and the real-time three-dimensional transthoracic image of the left atrial appendage from different observation planes (Figures 2A, 2B and 2C), as from the frontal plane (en face). Currently, transesophagic echocardiography is still the most appropriate echocardiographic technique for visualization of the left atrial appendage and investigation of intracavitary thrombi, as it shows evidence based on analyses with a large number of patients. Further studies are needed for a definition of the diagnostic and prognostic impact of the anatomical findings obtained by the use of real-time threedimensional transthoracic echocardiography.

Frequency response of different couplant materials for mounting transducers

Sensors often are piezoelectric crystal transducers that convert movement (a variation of pressure) into an electrical voltage. Several non-destructive techniques involve the use of transducers, such as sonic testing, tomography, acoustic emission and pulse-impact echo. There are different types of transducers according to their different aims and applications, but in all cases the mounting of a sensor is an essential requirement in order to record good quality data—a good acoustic coupling between the transducer and the surface of the structure has to be ensured. It is common practice to use Cyanoacrylate adhesive glue (e.g. superglue) for most applications, but the authors found its use problematic during temporary installations due to the difficulties encountered to remove the sensor at the end of the experiment. For this reason, a study has been carried out to investigate possible alternative couplant materials. Eight different materials have been selected, and their amplitude of response in terms of time-domain and the frequency-domain has been compared. A final evaluation based on several pre-defined criteria has then been obtained, showing the feasibility of ‘plasticine’ as a valid alternative to superglue.

A dynamic study of thoracolumbar burst fractures.

The degree of canal stenosis following a thoracolumbar burst fracture is sometimes used as an indication for decompressive surgery. This study was performed to test the hypothesis that the final resting positions of the bone fragments seen on computed tomography imaging are not representative of the dynamic canal occlusion and associated neurological damage that occurs during the fracture event. A drop-weight method was used to create burst fractures in bovine spinal segments devoid of a spinal cord. During impact, dynamic measurements were made with use of transducers to measure pressure in a synthetic spinal cord material, and a high-speed video camera filmed the inside of the spinal canal. A corresponding finite element model was created to determine the effect of the spinal cord on the dynamics of the bone fragment. The high-speed video clearly showed the fragments of bone being projected from the vertebral body into the spinal canal before being recoiled, by the action of the posterior longitudinal ligament and intervertebral disc attachments, to their final resting position. The pressure measurements in the synthetic spinal cord showed a peak in canal pressure during impact. There was poor concordance between the extent of postimpact occlusion of the canal as seen on the computed tomography images and the maximum amount of occlusion that occurred at the moment of impact. The finite element model showed that the presence of the cord would reduce the maximum dynamic level of canal occlusion at high fragment velocities. The cord would also provide an additional mechanism by which the fragment would be recoiled back toward the vertebral body. A burst fracture is a dynamic event, with the maximum canal occlusion and maximum cord compression occurring at the moment of impact. These transient occurrences are poorly related to the final level of occlusion as demonstrated on computed tomography scans.

Trade-offs between the axial resolution and the signal-to-noise ratio in elastography

Elastography involves tracking the ultrasonic A-mode signals before and after mechanical compression of tissue to form a computed image of the local strains undergone by various tissue components. The quality of the strain estimates in elastography is typically quantified using factors such as the elastographic SNR ( SNR e ), contrast-to-noise ratio ( CNR e ), and the spatial resolution. These quality factors depend on the mechanical parameters (such as the applied strain and the boundary conditions), the acoustic parameters (such as the sonographic SNR, the center frequency, and the bandwidth), and the signal-processing parameters (such as the window length and the window separation). Theoretical developments in elastography have established functional relationships between the SNR e and CNR e and these parameters. Similarly, simulations have established empirical relationships between the axial resolution and the acoustic and signal-processing parameters. We find that a trade-off exists between the achievable SNR e ( CNR e ) and the axial resolution in elastography and that the trade-off occurs only with respect to the signal-processing parameters. Theoretical work on the spatial resolution accompanied with simulations and experiments were used to confirm such an observation. The trade-off between the SNR e ( CNR e ) and the resolution was found to be nonlinear, with large improvements in the SNR e being possible at the expense of small reductions in the axial resolution. All the quality factors improve with the acoustic parameters, which suggests the preferred use of transducers with high absolute bandwidths and center frequencies. (E-mail: Jonathan.Ophir@uth.tmc.edu)

Covalent strategy for immobilization of DNA-microspots suitable for microarrays with label-free and time-resolved optical detection of hybridization.

Sequence-specific detection and quantification of nucleic acids are central steps in many molecular biology procedures which have also been transferred to chip-based procedures. Hybridization-based assays can be used to quantify and discriminate between DNA target sequences down to the level of single base mismatches. Arrays of DNA probes immobilized on a support enable simultaneous testing of multiple sequences of a single sample. DNA arrays can be produced either by in-situ synthesis of oligonucleotides or by immobilization of pre-assembled DNA probes. Covalent and directed immobilization improves the reproducibility and stability of DNA arrays. This is especially interesting with repeated use of transducers or chips. Procedures are described for effective covalent immobilization of pre-assembled amino-linked oligonucleotides, by use of ink-jet techniques, on a modified and heated glass surface, with addressable surface areas ranging from 0.01 mm2 to a few mm2. Almost immediate evaporation of the spotted droplets on the heated surfaces leads to very high surface hybridization capacities. The surfaces are suitable for use with a label-free detection method - reflectometric interference spectroscopy (RIfS). It is shown that hybridization capacity and non-specific interaction at these DNA-surfaces can be characterized by use of RIfS. With a consumption of less than 80 ng mm(-2) oligonucleotide and a specific hybridization capacity of more than 300 fmol mm(-2), the activated aminodextran procedure was usually suitable for setting up a DNA array with label-free detection. Non-specific interactions with random oligomers or protein (ovalbumin) were low. Up to 150 repeated regenerations (stripping) of the surfaces by acid treatment and denaturing agents, and 50 days of storage, have been possible without significant loss of hybridization capacity.

An experimental method to study high speed sliding characteristics during forward and reverse slip

This paper introduces an experimental technique to investigate dynamic friction characteristics of sliding interfaces at normal pressures up to 125 MPa, slip speeds up to 15 m/s and slip distances of approximately 10 mm. This new apparatus involves a novel modification of the conventional torsional Kolsky bar apparatus employed extensively in the past to investigate high-strain-rate behavior of engineering materials. The experimental configuration allows critical frictional parameters such as the friction-stress, slip speed and slip displacement to be resolved on a micro-second time scale without the use of transducers at the frictional interface. Moreover, the experiment provides information on the evolution of dynamic friction stress during forward as well as reverse slip. Using this experimental configuration dynamic friction experiments were conducted on 6061-Al (T6)/1018 steel and 7075-Al (T6)/tool-steel (D3) tribo-pairs. The results of experiments on 6061-Al (T6)/1018 steel indicate that steady-state kinetic friction is obtained within the rise time of the torsional loading pulse. The coefficient of kinetic friction is observed to increase with the roughness of the tribo-pair surfaces. For a soft/hard tribo-pair interface (7075 Al/tool-steel (D3)) the surface roughness of the harder material (tool-steel (D3)) constituting the tribo-pair is observed to control the frictional force. The measured coefficient of kinetic friction is approximately independent of the interfacial slip velocity for sliding velocities in the range of 2–10 m/s and normal pressures of approximately 100 MPa. Moreover, it is observed that the dynamic friction stress during reverse slip is almost twice as large when compared to friction stress in the forward direction. This increase in friction stress is understood to be due to frictional contact between fresh metallic surfaces formed by the breakdown of oxide and other surface films and anisotropy in frictional surfaces developed during the forward slip.

Use of transducers and determination of shape factors in water-pressure (packer) tests

Use of transducers and determination of shape factors in water-pressure (packer) tests