Piezoelectric Ultrasonic Transducer Research Articles

Measurement insights and error analysis of electronic parameters for ultrasonic transducers

Abstract Piezoelectric ultrasonic transducers with the function of energy conversation, as well as their numerous advantages in high-power density, quick response, flexible design, and service reliability, are involved in wide applications of industrial processing, precision driving, smart sensing, and medical services. The electromechanical equivalent circuit and Kirchhoff’s law indicate that mechatronics parameters are essential for performance evaluation, reliability analysis, and fault diagnosis of ultrasonic transducers. Importantly, the ultrasonic transducer is a time-variant system, data of one single parameter collected from a certain test cannot match with the data of another single parameter acquired from a different test. So, a synchronous and precise online measurement of electronic parameters is encouraged for performance evaluation and optimization design of ultrasonic transducers. With the combination of virtual instrument technology, an asynchronous measurement system of electrical excitation parameters for the ultrasonic transducers of linear driving motors was established in this study. Furthermore, the systematic measurement methods and error theory were illustrated, including the calculation methods and measuring circuits of electric signals. Experimental results proved that the proposed system and methods for measuring the input electronic power of ultrasonic transducer (e.g. effective value method for voltage and current, energy moment method for frequency, and spectrum analysis method for phase difference) are highly precise, quickly responsive, robust, and reliable for ultrasonic transducers. The findings of this study provide valuable references and suggestions for efficient, accurate, and online performance evaluation of ultrasonic transducers, particularly for piezoelectric transducers utilizing ultrasonic high-voltage exciting signals.

Investigation of an Active Focusing Planar Piezoelectric Ultrasonic Transducer

Ultrasonic focusing transducers have broad prospects in advanced ultrasonic non-destructive testing fields. However, conventional focusing methods that use acoustic concave lenses can disrupt the acoustic impedance matching condition, thereby adversely affecting the sensitivity of the transducers. In this paper, an active focusing planar ultrasonic transducer is designed and presented to achieve a focusing effect with a higher sensitivity. An electrode pattern consisting of multiple concentric rings is designed, which is inspired by the structure of Fresnel Zone Plates (FZP). The structural parameters are optimized using finite element simulation methods. A prototype of the transducer is manufactured with electrode patterns made of conductive silver paste using silk screen-printing technology. Conventional focusing transducers using an acoustic lens and an FZP baffle are also manufactured, and their focusing performances are comparatively tested. The experimental results show that our novel transducer has a focal length of 16 mm and a center frequency of 1.16 MHz, and that the sensitivity is improved by 23.3% compared with the conventional focusing transducers. This research provides a new approach for the design of focusing transducers.

Structural Optimization Study on a Three-Degree-of-Freedom Piezoelectric Ultrasonic Transducer

A three-degree-of-freedom (3-DOF) piezoelectric ultrasonic transducer is a critical component in elliptical and longitudinal ultrasonic vibration-assisted cutting processes, with its geometric structure directly influencing its performance. This paper proposes a structural optimization method based on a convolutional neural network (CNN) and non-dominated sorting genetic algorithm II (NSGA2). This method establishes a transducer lumped model to obtain the electromechanical coupling coefficients (X-ke and Z-ke) and thermal power (X-P) indicators, evaluating the bending and longitudinal vibration performance of the transducer. By creating a finite element model of the transducer with mechanical losses, a dataset of different transducer performance parameters, including the tail mass, piezoelectric stack, and dimensions of the horn, is obtained. Training a CNN model with this dataset yields objective functions for the relationship between different transducer geometric structures and performance parameters. The NSGA2 algorithm solves the X-ke and Z-ke objective functions, obtaining the Pareto set of the transducer geometric dimensions and determining the optimal transducer geometry in conjunction with X-P. This method achieves simultaneous improvements in X-ke and Z-ke of the transducer by 22.33% and 25.89% post-optimization and reduces X-P to 18.97 W. Furthermore, the finite element simulation experiments of the transducer validate the effectiveness of this method.

In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion

ObjectivesTo compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts.Materials and methodsA periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation.ResultsAll tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation.ConclusionsThe planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material.Clinical relevanceUltrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

Biomimetic Ultrasonic Vibrator with Broadband Characteristics Inspired by Leaf-Cutting Ants.

Power ultrasound is widely used in industrial production, medical equipment, aerospace, and other fields. Currently, there are two main types of commonly used power generation devices: piezoelectric ultrasonic transducers and magnetostrictive ultrasonic transducers. However, in certain situations with limited external dimensions, the applications of existing power ultrasound devices are limited. In nature, leaf-cutting ants excite vibrations through their tiny organs. Inspired by the vibratory organs of leaf-cutting ants, a new type of biomimetic ultrasonic vibrator (BUV) comprising a scraper, dentate disc, and fixture system was proposed, fabricated, and tested in this study. The experimental results showed that the BUV could operate in the frequency range of 16.8-19 kHz. Within the working frequency range, the vibration of the BUV was stable and the amplitude of the vibration displacement was greater than 22 µm. The operating frequency band of the BUV was broader than those of the piezoelectric and magnetostrictive ultrasonic transducers. In addition, the BUV can cut soft rubber and pig tissues with sufficient output power and load-carrying capacity. The BUV, as a new type of power ultrasonic excitation device, is expected to be applied in high-power micro operating scenarios, such as minimally invasive surgical instruments.

Enhanced high-frequency piezoelectric ultrasonic transducer based on integrated AlN honeycomb structure

Ultrasonic transducers are vital components for transmitting and receiving sound waves, which are customized to specific applications based on their operating frequencies.Small-sized high-frequency ultrasonic transducers have gained considerable attention and adoption in medical ultrasound imaging and small pipe flow testing. However, the significant impact of attenuation on high-frequency ultrasound restricts detection distance and degrades the signal-to-noise ratio. Additionally, thin-film high-frequency ultrasound transducers exhibit low output sound pressure, due to their low resonance displacement. In this study, we present an innovative approach to address these challenges through the design of an integrated small-size honeycomb-type top, two-electrode aluminum nitride (AIN)-based high-frequency ultrasonic transducer. A comprehensive investigation of the relationship between transducer size, sensitivity, and transmitted sound pressure levels is conducted. Leveraging microelectromechanical systems (MEMS) micro-nano-machining technology, we fabricate a 14 × 13 array with a unit diameter of 50 µm, and a matching circuit is employed to enhance the transducer's amplitude. Experimental results demonstrate remarkable transmit sound pressure levels (SPL) exceeding 210 dB (re:1 µPa/V) at a distance of 2 cm, with a maximum transmit SPL of 233 dB, and the receive sensitivity surpasses − 175 dB (re:1 V/µPa) and, at the 5 MHz resonance, the sensitivity reaches − 143 dB (re:1 V/µPa). Moreover, the transmit and receive linearity values demonstrate 99% and 98%, respectively. Our findings highlight the significant potential of the proposed high-frequency ultrasonic transducer for a diverse range of applications.

Frequency tuning and automatic frequency tracking of shunted piezoelectric transducers

Piezoelectric ultrasonic transducers, vital in medical devices and aerospace, often face challenges like resonant frequency shifts and impedance variations affecting their operational efficiency. This paper introduces a shunted piezoelectric transducer which could tune itself by digitally programmable inductance. A transformer and inductance-capacitance matching network ensures enhanced compatibility and impedance management. Proposing a fuzzy PI-based phase control method achieves resonant frequency tracking, synchronizing operational frequency with the transducer. In contrast to traditional methods, our approach enables faster and more precise fine-tuning, detecting and rectifying real-world deviations for optimal performance. A comprehensive experimental validation, based on fundamental knowledge analysis, confirms the feasibility and superiority of our proposed method, and the commonly encountered issues of resonance frequency deviation and impedance variation in high-power piezoelectric transducer applications can be effectively mitigated.

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer.

Piezoelectric micromachined ultrasound transducers (PMUTs) have gained significant popularity in the field of ultrasound ranging and medical imaging owing to their small size, low power consumption, and affordability. The scar-free "MIS" (micro-hole inter-etch and sealing) process, a novel bulk-silicon manufacturing technique, has been successfully developed for the fabrication of pressure sensors, flow sensors, and accelerometers. In this study, we utilize the MIS process to fabricate cavity diaphragm structures for PMUTs, resulting in the formation of a flat cavity diaphragm structure through anisotropic etching of (111) wafers in a 70 °C tetramethylammonium hydroxide (TMAH) solution. This study investigates the corrosion characteristics of the MIS technology on (111) silicon wafers, arranges micro-pores etched on bulk silicon around the desired cavity structure in a regular pattern, and takes into consideration the distance compensation for lateral corrosion, resulting in a fully connected cavity structure closely approximating an ortho-hexagonal shape. By utilizing a sputtering process to deposit metallic molybdenum as upper and lower electrodes, as well as piezoelectric materials above the cavity structure, we have successfully fabricated aluminum nitride (AlN) piezoelectric ultrasonic transducer arrays of various sizes and structures. The final hexagonal PMUT cells of various sizes that were fabricated achieved a maximum quality factor (Q) of 251 and a displacement sensitivity of 18.49 nm/V across a range of resonant frequencies from 6.28 MHz to 11.99 MHz. This fabrication design facilitates the achievement of IC-compatible and cost-effective mass production of PMUT array devices with high resonance frequencies.

Conformable Shear Mode Transducers from Lead‐Free Piezoelectric Ceramic Coatings: An Innovative Ultrasonic Solution for Submerged Structural Health Monitoring

AbstractShear mode‐guided ultrasonic waves are highly regarded for submerged or subterranean structural health monitoring (SHM), owing to their non‐dispersive feature and minimized acoustic energy loss when in contact with liquid or solid. High‐performance shear mode ceramic ultrasonic transducers with robustness and cost‐effectiveness are highly demanded for underwater or underground SHM applications, especially in harsh environments. However, the implementation of discrete shear mode piezoelectric ceramic ultrasonic transducers is hindered by the inconsistency with manual installation, lack of conformability on curved surfaces, and unreliable acoustic coupling between the transducers and the structure. Here, direct‐write conformable shear mode ultrasonic transducers made from piezoelectric lead‐free ceramic coatings, which are in situ produced on steel structures by a scalable thermal spray process, are proposed. The obtained lead‐free lithium‐doped potassium sodium niobate (KNN‐LN) ceramic coatings exhibit a high effective shear piezoelectric strain coefficient (d24, f) above 60 pm V−1 in a broad frequency range from 100 Hz to 200 kHz. The resulting conformable shear mode KNN‐LN ceramic coating transducers successfully showcase the functions of exciting and detecting stable shear mode ultrasonic wave signals with operation temperature exceeding 200 °C and demonstrate reliable capability in defect detection in both air and liquid environments.

Piezoelectric metasurface for high-frequency ultrasonic transducer application around 50 MHz

High-frequency ultrasound plays a vital role in ultrasonic imaging and particle manipulation. However, the control of high-frequency ultrasound fields with traditional acoustic lens presents challenges in impedance matching, precise control, material selection. Therefore, piezoelectric ultrasonic transducers prepared based on traditional methods are difficult to achieve high frequency and efficient sound beam control. To address these challenges, we have developed a piezoelectric metasurface-based ultrasonic transducer, using the encode binary information method to modulate acoustic waves. Simulation results reveal that at a frequency of 50 MHz, the system exhibits efficient acoustic focusing capabilities, which have been successfully applied in the experimental trapping of microspheres with acoustic tweezers. The design and development of high-frequency ultrasound transducers have emerged as a burgeoning research area at the confluence of acoustics and numerous interdisciplinary fields.

BiScO3-PbTiO3 based high temperature piezoelectric ceramics composite ultrasonic transducer

Utilizing the electrical resonance method, matrices encompassing elastic, piezoelectric, and dielectric properties were calculated for 0.36BiScO3-0.64PbTiO3 (BSPT) ceramics. The design parameters for the BSPT/epoxy 2-2 composite material were meticulously elucidated through simulations conducted via COMSOL software. Characterization outcomes unveil that the synthesized composite material exhibits diminished acoustic impedance and heightened electromechanical coupling in comparison to its piezoelectric ceramic counterparts. Subsequent to the design and fabrication of ultrasonic transducers employing both BSPT ceramics and BSPT/epoxy 2-2 composite material, a thorough investigation into their electrical and acoustic attributes ensued at ambient temperature and 200 °C. Test results manifest that the BSPT/epoxy 2-2 composite high temperature ultrasonic transducer (CHTUT) demonstrates a center frequency and bandwidth of 4.52 MHz and 54.71%, respectively, at room temperature. While, at 200 °C, these parameters are 3.54 MHz and 80.79%. The HTUT, under parallel scrutiny, exhibits a center frequency and bandwidth of 4.65 MHz and 34.23% at room temperature, respectively, and 4.52 MHz and 29.65% at 200 °C. These findings prove the robust ultrasonic performance of the CHTUT, even under elevated temperatures, with the BSPT ceramic based counterpart demonstrating superior temperature stability. Furthermore, the results of an imaging experiment involving steel step blocks at both room temperature and 200 °C align consistently with the acoustic test outcomes.

Experimental Analyses and Predictive Modelling of Ultrasonic Welding Parameters for Enhancing Smart Textile Fabrication.

This study aims to illustrate the design, fabrication, and optimisation of an ultrasonic welding (UW) machine to join copper wires with non-woven PVC textiles as smart textiles. The study explicitly evaluates UW parameters' impact on heat generation, joint strength, and electrical properties, with a comprehensive understanding of the process dynamics and developing a predictive model applicable to smart textiles. The methodological approach involved designing and manufacturing an ultrasonic piezoelectric transducer using ABAQUS finite element analyses (FEA) software and constructing a UW machine for the current purpose. The full factorial design (FFD) approach was employed in experiments to systematically assess the influence of welding time, welding pressure, and copper wire diameter on the produced joints. Experimental data were meticulously collected, and a backpropagation neural network (BPNN) model was constructed based on the analysis of these results. The results of the experimental investigation provided valuable insights into the UW process, elucidating the intricate relationship between welding parameters and heat generation, joint strength, and post-welding electrical properties of the copper wires. This dataset served as the basis for developing a neural network model, showcasing a high level of accuracy in predicting welding outcomes compared to the FFD model. The neural network model provides a valuable tool for controlling and optimising the UW process in the realm of smart textile production.

Harmonic Excitation Response of Standard Ultrasonic Horn Designs for Machining Nomex Honeycomb Core Composite

Ultrasonic horn plays a vital role in achieving vibration amplitude at tool end (VATE) by enhancing output displacement of piezoelectric ultrasonic transducer suitable for efficient machining of advanced composites. Higher vibration amplitude enhances ultrasonic machining quality, surface integrity and dimensional accuracy of Nomex honeycomb composite (NHC) while reducing cutting forces. Furthermore, low stress concentrations allow ultrasonic tool to have more safety factor and longevity. Ultrasonic horn is designed to enhance displacement amplitude of piezoelectric ultrasonic transducer and get optimum VATE while keeping stresses in acceptable limits to avoid failure at very high operating frequency of ultrasonic machining system. In this research, variety of standard ultrasonic horns (SUH) were designed with same length and end diameters; and were tested under similar operating conditions, using finite element method. The ultrasonic actuation of the horn exploits the first axial mode of horn vibration. Harmonic response analysis was carried out to determine axial modal frequencies (AMF), VATE, stresses, and factor of safety for performance evaluation. VATE attained by step horn was found to be greatest among all other SUHs for frequency ratio greater than one, but may be prone to early failure due to high stress concentrations. VATE achieved by third order Bezier, Gaussian, exponential, catenoidal, conical and second order Bezier horns were found less than that of step horn by 11.7 %, 16.6 %, 16.7 %, 17 %, 16.73 % and 18 % respectively. However, 44.2 %, 43.43 %, 42.5 %, 43.5 %, 42.8 % and 37.67 % reduction of stresses was achieved by Gaussian, exponential, catenoidal, conical, second and third order Bezier horns respectively. Outcomes of present work would be beneficial for designers, researchers, scientists, and manufacturers of ultrasonic machine tool to select appropriate SUH designs according to requirements.

Effect of humid environment on electromechanical performance of piezoelectric micromachined ultrasonic transducers (PMUTs)

In recent years, piezoelectric micromechanical ultrasonic transducers (PMUTs) have received widespread attention. The deployment of PMUTs in humid environment exposes them to changes in relative humidity, which effects their electromechanical performance. This paper investigates the effect of humid environments (30 %−80 %) on the electromechanical performance of uncoated PMUTs from the perspective of electromechanical conversion model and equivalent circuit. Two types of transducers with different top layer materials were experimented to compare the effects of moisture absorption on the electromechanical performances of the transducers. The top layer material of Device A is SiO2 film, and the top layer material of Device B is Si3N4 film. The experimental results show that with the rise of relative humidity, the frequency of Device A decreases by −0.47 %, while the frequency of Device B increases by 0.13 %, and the phase resonance peaks of both increases by 0.441° and 0.285°, respectively. Equivalent circuit fitting was conducted on the impedance characteristics of Device A and Device B, and the fitting results were discussed based on acoustic impedance and moisture absorption theory. The electromechanical performances of the two devices show a different variation trend, with the potential reason being that Device A is mainly affected by the combined effects of moisture absorption leading to a decrease in Young’s modulus of the membrane and a decrease in the acoustic impedance of the humid air, while Device B is mainly affected by the acoustic impedance.

Multi-mode coupled vibration analysis and radiation sound field investigation of a novel multidirectional piezoelectric ultrasonic transducer

Nowadays, expanding the operating range and realizing multifrequency operation have emerged as focal and imperative objectives in the design of ultrasonic transducers. Due to the limitations of structure and radial sizes, conventional Langevin transducers encounter challenges in meeting the increasingly stringent requirements across diverse ultrasonic applications. Hence, this paper proposes a multidirectional piezoelectric ultrasonic transducer (MPUT) consisting of a large-dimension sandwich piezoelectric transducer (LSPT) and a metal tube in mutli-mode coupled vibration, capable of achieving wide-ranging and multifrequency acoustic radiation. Based on the analytical method, a two-dimensional electromechanical equivalent circuit model (2D-EECM) of the MPUT is established, and its frequency calculation results are validated through the finite element method (FEM) and impedance analysis experiment. The vibration testing results indicate that adjusting the radial size can control the coupled vibration intensity of the MPUT and achieve dual-frequency and multidirectional uniform radiation. The radiation sound field testing results confirm the MPUT's satisfactory three-dimensional radiation capability in water and significant improvement in acoustics operating range.

Design, preparation and electromechanical characteristics analysis of piezoelectric 1-3-type composites with sandwich polymer structures

Aiming at the shortcomings of the traditional 200 kHz 1–3 piezoelectric composites with a thickness of 7.5 mm, which have a lower electromechanical coupling coefficient, lower resolution and larger acoustic impedance, a piezoelectric 1–3-type composites with sandwich polymer structures with higher electromechanical coupling coefficient and lower acoustic impedance was designed in this paper. First, the piezoelectric composites with different volume fractions of piezoelectric ceramics and silicone rubber were simulated by COMSOL software, and the optimal volume fractions of piezoelectric ceramics and silicone rubber were obtained. Second, the first and second lateral mode frequencies of the piezoelectric 1–3-type composites with sandwich polymer structures with different kerf widths were calculated. Then, based on the electromechanical equivalent circuit, the electromechanical characteristics of the piezoelectric 1–3-type composites with sandwich polymer structures were analyzed, and the equivalent performance parameters of the piezoelectric composite were obtained. Compared with other 7.5 mm thickness 1–3 piezoelectric composites, it was found that the electromechanical coupling coefficient of the piezoelectric 1–3-type composites with sandwich polymer structures is significantly increased, and the acoustic impedance is significantly decreased. Therefore, the piezoelectric 1–3-type composites with sandwich polymer structures has great potential advantages in the preparation of high-performance piezoelectric ultrasonic transducers.

Ultrasonic monitoring of hydration behavior of cement paste doped with triethanolamine using novel piezoelectric ultrasonic transducer

The propagation of ultrasonic wave in cement paste is closely related to its physical properties, and therefore shows a potential application in fields of online monitoring of hydration and hardening properties of the cementitious materials. Here, the hydration characteristics of cement paste doped with triethanolamine were studied based on the ultrasonic transmission method using the tailor-made horizontal omnidirectional piezoelectric ultrasonic transducer. The results show that clear ultrasonic waveforms can be observed at hydration age of 2 h. The dominant frequency of the reception wave is low at early hydration age and shifts towards the high frequency direction with hydration. The amplitude of the head wave increases sharply before hydration of 24 h, and the increasing extent decreases gradually until hydration of 166 h. The hydration process of cement at early hydration age can be classified into three stages based on amplitude changes of the head wave, that is, the induction period before 4 h, the acceleration period during 4–12 h, and the deceleration period after 12 h. The acoustic parameters of cement paste at early hydration age conform well to the logistic function distribution. The research finding might provide a new method to estimate hydration and hardening properties of cementitious materials, especially on large construction sites.

Влияние геометрической формы демпфера на эффективность работы ультразвукового пьезоэлектрического преобразователя

Purpose of the work: To evaluate the influence of the geometric shape of the damper in the form of a truncated cone on the efficiency of the ultrasonic piezoelectric transducer. Materials and methods: Numerical and experimental modeling of the processes of propagation of ultrasonic signals in the damper of an ultrasonic transducer was used. Results: A damper in the form of a truncated cone is considered, the generatrix of which has an angle of inclination α with respect to the diameter of the piezoceramic plate. The shape of the damper in the form of a truncated cone is chosen based on the a priori assumption that this contributes to an increase in the path of the wave in the damper material due to numerous reflections inside it. A criterion for the efficiency of the damper is proposed. Theoretically and experimentally, the optimal (from the point of view of the efficiency of the damper) value of the angle α was determined. The technology of its manufacture is described. A satisfactory agreement between the results of theoretical and experimental studies was noted. Conclusion: The efficiency of a conical damper filled with a mixture of tungsten powder and KDA resin in a 1:1 ratio is higher than that of a cylindrical damper. A damper made from such a mixture can be effectively used in the manufacture of converters with a frequency of at least 2.5 MHz. For lower frequencies, it is required to select a different damping composition with a different filler or with a different ratio of its constituent components. The maximum efficiency of a cone damper is achieved when the cone generatrix is tilted α = 64…66.

Miniature Ultrasonic Spatial Localization Module in the Lightweight Interactive.

The advancement of spatial interaction technology has greatly enriched the domain of consumer electronics. Traditional solutions based on optical technologies suffers high power consumption and significant costs, making them less ideal in lightweight implementations. In contrast, ultrasonic solutions stand out due to their lower power consumption and cost-effectiveness, capturing widespread attention and interest. This paper addresses the challenges associated with the application of ultrasound sensors in spatial localization. Traditional ultrasound systems are hindered by blind spots, large physical dimensions, and constrained measurement ranges, limiting their practical applicability. To overcome these limitations, this paper proposes a miniature ultrasonic spatial localization module employing piezoelectric micromechanical ultrasonic transducers (PMUTs). The module is comprised of three devices each with dimension of 1.2 mm × 1.2 mm × 0.5 mm, operating at a frequency of around 180 kHz. This configuration facilitates a comprehensive distance detection range of 0-800 mm within 80° directivity, devoid of blind spot. The error rate and failure range of measurement as well as their relationship with the SNR (signal-to-noise ratio) are also thoroughly investigated. This work heralds a significant enhancement in hand spatial localization capabilities, propelling advancements in acoustic sensor applications of the meta-universe.

Hybrid de-icing method combining electrothermal system and ultrasonic guided waves

A novel hybrid de-icing method combining an electrothermal system and ultrasonic guided waves is proposed for the leading edge structure of wind turbine blades. The adhesion strength between the ice layer and the leading-edge structure is reduced by the electrothermal system. Piezoelectric ultrasonic transducers are used to generate shear stresses to crack and remove ice. The heating resistance wires and transducers are pasted onto the inner surface of the leading-edge structure. The spacing of the resistance wires was calculated by a theoretical thermal model. A temperature recorder was used to measure the temperature changes at different measuring points on the leading-edge surface under electric heating. This study conducted ultrasonic guided waves de-icing, electrothermal de-icing, and combined electrothermal–ultrasonic de-icing experiments in a freezer with an airfoil leading edge model. The results reveal that the combined electrothermal–ultrasonic method is feasible and has great potential for ice shedding acceleration.