Acoustic Radiation Research Articles

An adapted two-step approach to simulate nonlinear vibrations of patterned tires rolling on a smooth surface

The tire/road noise is one of the major problems facing the tire industry due to the nuisance felt by the vehicle's driver and passengers. Moreover, it is expected in the coming years that this sound nuisance will be one of the main sources of vehicle noise due to the transition from combustion engine driven vehicles to electric vehicles. Tire manufacturers have therefore refined the design of their tire structures to find technological solutions to reduce traffic noise. Tire/road noise is also generated by various mechanisms which depend on different parameters such as the properties of the tire, road texture and driving conditions. This noise is partly caused by the acoustic radiation induced by the tire vibrations due to contacts with the road. The simulation and analysis of the tire's vibrations remains a challenge for the tire industry. Indeed, the simulation of the full dynamic response of a rolling patterned tire requires not only taking onto account various nonlinearities but also the multi-scale nature of the generated dynamic response. Contrary to a straightforward strategy that consists in using a time integrator to predict the multi-scale dynamic response, the strategy proposed in this study is based on a two-step approach to separate the dynamics occurring at different scales. The mathematical formulation of the proposed method is detailed as are the different modeling choices to simulate tire rolling under imposed load. The sensitivity of the tire's vibrations response is analyzed under different rolling conditions and with respect to certain key tire tread pattern parameters.

Ultrasonic Healing of Plastrons.

Superhydrophobic surfaces (SHS) exhibit a pronounced ability to resist wetting. When immersed in water, water does not penetrate between the microstructures of the SHS. Instead, a thin layer of trapped gas remains, i.e., plastron. This fractional wetting is also known as the Cassie-Baxter state (CB). Impairment of superhydrophobicity occurs when water penetrates the plastron and, when complete wetting is achieved, a Wenzel state (W) results. Subsequent recovery back to CB state is one of the main challenges in the field of SHS wetting. Current methods for plastron recovery require complex mechanical or chemical integration, are time-consuming or lack spatial control. Here an on-demand, contact-less approach for performing facile transitions between these wetting states at micrometer length scales is proposed. This is achieved by the use of acoustic radiation force (ARF) produced by high-intensity focused ultrasound (HIFU). Switching from CB to W state takes <100 µs, while the local recovery back to CB state takes <45 s. To the best of authors knowledge, this is the first demonstration of ARF-induced manipulation of the plastron enabling facile two-way controlled switching of wettingstates.

Quantitative Viscoelastic Response (QVisR): Direct Estimation of Viscoelasticity With Neural Networks.

We present a machine learning method to directly estimate viscoelastic moduli from displacement time-series profiles generated by viscoelastic response (VisR) ultrasound excitations. VisR uses two colocalized acoustic radiation force (ARF) pushes to approximate tissue viscoelastic creep response and tracks displacements on-axis to measure the material relaxation. A fully connected neural network is trained to learn a nonlinear mapping from VisR displacements, the push focal depth, and the measurement axial depth to the material elastic and viscous moduli. In this work, we assess the validity of quantitative VisR (QVisR) in simulated materials, propose a method of domain adaption to phantom VisR displacements, and show in vivo estimates from a clinically acquired dataset.

Contribution Ratio of Excitation Sources to the Underwater Acoustic Radiation of the X-BOW Polar Exploration Cruise Ship

Contribution Ratio of Excitation Sources to the Underwater Acoustic Radiation of the X-BOW Polar Exploration Cruise Ship

Acoustic radiation force-induced longitudinal shear wave for ultrasound-based viscoelastic evaluation

Acoustic radiation force (ARF) is widely used to induce shear waves for evaluating the mechanical properties of biological tissues. Two shear waves can be generated when exciting with ARF: a transverse shear wave, also simply called shear wave (SW), and a longitudinal shear wave (LSW). Shear waves (SWs) have been broadly used to assess the mechanical properties. Some articles have reported that the LSW can be used to evaluate mechanical properties locally. However, existing LSW studies are mainly focused on the group velocity evaluation using optical coherence tomography (OCT). Here, we report that a LSW generated with ARF can be used to probe viscoelastic properties, including shear modulus and viscosity, using ultrasound. We took advantage of the surface boundary effect to reflect the LSW, named RLSW, to address the energy deficiency of LSW induced by ARF. We systematically evaluated the experiments with tissue-mimicking viscoelastic phantoms and validated by numerical simulations. Phase velocity and dispersion comparison between the results induced by a RLSW and a SW exhibit good agreement in both the numerical simulations and experimental results. The Kelvin-Voigt (KV) model was used to determine the shear modulus and viscosity. RLSW shows great potential to evaluate localized viscoelastic properties, which could benefit various biomedical applications such as evaluating the viscoelasticity of heterogeneous materials or microscopic lesions of tissues.

Airborne Acoustic Vortex End Effector-based Contactless, Multi-mode, Programmable Control of Object Surfing.

Tweezers based on optical, electric, magnetic, and acoustic fields have shown great potential for contactless object manipulation. However, current tweezers designed for manipulating millimeter-sized objects such as droplets, particles, and small animals, exhibit limitations in translation resolution, range, and path complexity. Here, we introduce a novel acoustic vortex tweezers system, which leverages a unique airborne acoustic vortex end effector integrated with a three degree-of-freedom (DoF) linear motion stage, for enabling contactless, multi-mode, programmable manipulation of millimeter-sized objects. The acoustic vortex end effector utilizes a cascaded circular acoustic array, which is portable and battery-powered, to generate an acoustic vortex with a ring-shaped energy pattern. The vortex applies acoustic radiation forces to trap and spin an object at its center, simultaneously protecting this object by repelling other materials away with its high-energy ring. Moreover, our vortex tweezers system facilitates contactless, multi-mode, programmable object surfing, as demonstrated in experiments involving trapping, repelling, and spinning particles, translating particles along complex paths, guiding particles around barriers, translating and rotating droplets containing zebrafish larvae, and merging droplets. With these capabilities, we anticipate that our tweezers system will become a valuable tool for the automated, contactless handling of droplets, particles, and bio-samples in biomedical and biochemical research.

Protein Gas Vesicles of Bacillus megaterium as Enhancers of Ultrasound-Induced Transcriptional Regulation.

Gas vesicles (GVs) are large cylindrical gas-filled protein assemblies found in diverse aquatic bacteria that enable their adaptation of buoyancy. GVs have already been used as ultrasound contrasting agents. Here, we investigate GVs derived from Bacillus megaterium, aiming to minimize the number of accessory Gvps within the GV gene cluster and demonstrate the use of GVs as enhancers of acoustic radiation force administered by ultrasound. Three (GvpR, GvpT, and GvpU) out of 11 genes in the cluster were found to be dispensable for functional GV formation, and their omission resulted in narrower GVs. Two essential proteins GvpJ and GvpN were absent from recently determined GV structures, but GvpJ was nevertheless found to be tightly bound to the cylindrical part of GVs in this study. Additionally, the N-terminus of GvpN was observed to play an important role in the formation of mature GVs. The binding of engineered GvpC fromAnabaena flos-aquae to HEK293 cells via integrins enhanced the acoustic force delivered by ultrasound and resulted in an increased Ca2+ influx into cells. Coupling with a synthetic Ca2+-dependent signaling pathway GVs efficiently enhanced cell stimulation by ultrasound, which expands the potentials of noninvasive sonogenetics cell stimulation.

Evaluation Method for Underwater Ultrasonic Energy Radiation Performance Based on the Spatial Distribution Characteristics of Acoustic Power.

In recent years, underwater wireless ultrasonic energy transmission technology (UWUET) has attracted much attention because it utilizes the propagation characteristics of ultrasound in water. Effectively evaluating the performance of underwater ultrasonic wireless energy transmission is a key issue in engineering design. The current approach to performance evaluation is usually based on the system energy transfer efficiency as the main criterion, but this criterion mainly considers the overall energy conversion efficiency between the transmitting end and the receiving end, without an in-depth analysis of the characteristics of the distribution of the underwater acoustic field and the energy loss that occurs during the propagation of acoustic waves. In addition, existing methods focusing on acoustic field analysis tend to concentrate on a single parameter, ignoring the dynamic distribution of acoustic energy in complex aquatic environments, as well as the effects of changes in the underwater environment on acoustic propagation, such as spatial variability in temperature and salinity. These limitations reduce the usefulness and accuracy of models in complex marine environments, which in turn reduces the efficiency of acoustic energy management and optimization. To solve these problems, this study proposes a method to evaluate the performance of underwater ultrasonic energy radiation based on the spatial distribution characteristics of acoustic power. By establishing an acoustic power distribution model in a complex impedance-density aqueous medium and combining numerical simulation and experimental validation, this paper explores the spatial variation of acoustic power and its impact on the energy transfer efficiency in depth. Using high-resolution spatial distribution data and actual environmental parameters, the method significantly improves the accuracy of the assessment and the adaptability of the model in complex underwater environments. The results show that, compared with the traditional method, this method performs better in terms of the accuracy of the acoustic energy radiation calculation results, and is able to reflect the energy distribution and spatial heterogeneity of the acoustic source more comprehensively, which provides an important theoretical basis and practical guidance for the optimal design and performance enhancement of the underwater ultrasonic wireless energy transmission system.

Acoustofluidic separation of bacteria from platelets using tilted-angle standing surface acoustic wave

Separation of microscale objects, such as cells and bacteria, is an essential sample preparation step in various microfluidic applications in microbiology, chemistry, biology, and biomedicine. Microfluidic separation of bacteria from blood cells is highly in demand to prevent or investigate bacterial infectious diseases. Unlike red and white blood cells, platelets have a similar size distribution to that of bacteria, which makes bacteria separation from platelets technically challenging. Most previous techniques for microfluidic separation rely on size as a separation marker. These size-based separation methods are not applicable to separation of the same or similar-sized samples. Here, we propose an acoustofluidic method using tilted-angle standing surface acoustic wave (taSSAW) for label-free separation of the microscale objects of the same or similar size based on compressibility. From the experimental investigation with polymethylmethacrylate, polystyrene, and polycaprolactone microparticles of the same size, we found that less compressible objects migrated further when exposed to the taSSAW field formed within a microchannel. Based on the findings, we demonstrated that Escherichia coli (E. coli) can be separated from platelets because the taSSAW-induced acoustic radiation force acting on comparatively less compressible E. coli was greater than that applied to the platelets. Fluorescence microscopy, scanning electron microscope, hemocytometry, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and polymerase chain reaction were conducted to confirm the successful positive separation of bacteria from platelets with high purity of exceeding 96 % and recovery rate of exceeding 81 %.

Merging mechanical bound states in the continuum in high-aspect-ratio phononic crystal gratings

Mechanical bound states in the continuum (BICs) present an alternative avenue for developing high-frequency, high-Q mechanical resonators, distinct from the conventional band structure engineering method. While symmetry-protected mechanical BICs have been realized in phononic crystals, the observation of accidental mechanical BICs—whose existence is independent of mode symmetry and tunable by structural parameters—has remained elusive. This challenge is primarily attributed to the additional radiation channel introduced by the longitudinal component of elastic waves. Here, we employ a coupled wave theory to predict and experimentally demonstrate mechanical accidental BICs within a high-aspect-ratio gallium arsenide phononic crystal grating. We observe the merging process of accidental BICs with symmetry-protected BICs, resulting in reduced acoustic radiation losses compared to isolated BICs. This finding opens up new possibilities for phonon trapping using BIC-based systems, with potential applications in sensing, transduction, and quantum measurements.

Acoustic Radiation Force on an Arbitrarily Placed Elastic Spherical Shell near an Impedance Boundary for Bessel Waves

Acoustic Radiation Force on an Arbitrarily Placed Elastic Spherical Shell near an Impedance Boundary for Bessel Waves

Study on Structure-Borne Noise Characteristics of Long-Span Steel Truss Bridge in Urban Rail Transit

The application of long-span steel bridge in urban rail transit is becoming more and more extensive, but the structure-borne noise of steel bridge induced by passing train is also prominent. Research on the structure-borne noise problem of long-span steel bridge in urban rail transit has positive significance in promoting the sustainable development of steel bridge, and improving the quality of sound environment along rail transit. In this work, dynamic receptance principle, finite element method and statistical energy method are combined to establish the structure-borne noise prediction model of the long-span steel bridge, and the rationality and validity of the model are verified based on field measurement results. Based on the prediction model, the noise radiation characteristics of large-span steel truss bridge in urban rail transit are studied, and the following conclusions are drawn: The bridge deck has the strongest acoustic contribution ability, with the contribution rate of 33–44%, followed by the longitudinal web and transverse web, with the contribution rate of 23–30%, followed by the truss chord, with the contribution rate of 5–8%, and the truss web, longitudinal wing and transverse wing have weak contribution ability, with the contribution rate of less than 2%. The acoustic radiation efficiency of steel truss bridge components reaches its peak at the critical frequency, and the critical frequency is determined by the thickness of steel bridge plate components when the material parameters are fixed. Under ordinary track structures, the middle-to-high frequency noise distribution characteristics of large-span steel truss bridge structure are obvious. Damping pad floating slab track can effectively suppress the high-frequency noise of steel bridge, and the overall sound level can be reduced by about 11–14[Formula: see text]dB.

Boundary integrated neural networks and code for acoustic radiation and scattering

AbstractThis paper presents a novel approach called the boundary integrated neural networks (BINNs) for analyzing acoustic radiation and scattering. The method introduces fundamental solutions of the time‐harmonic wave equation to encode the boundary integral equations (BIEs) within the neural networks, replacing the conventional use of the governing equation in physics‐informed neural networks (PINNs). This approach offers several advantages. First, the input data for the neural networks in the BINNs only require the coordinates of “boundary” collocation points, making it highly suitable for analyzing acoustic fields in unbounded domains. Second, the loss function of the BINNs is not a composite form and has a fast convergence. Third, the BINNs achieve comparable precision to the PINNs using fewer collocation points and hidden layers/neurons. Finally, the semianalytic characteristic of the BIEs contributes to the higher precision of the BINNs. Numerical examples are presented to demonstrate the performance of the proposed method, and a MATLAB code implementation is provided as supplementary material.

An effective T-cells separation method in an acoustofluidic platform using a concave–convex electrode design

This study addresses the growing interest in developing new acoustophoresis designs for efficient particle separation, introducing a novel concave–convex electrode design for lymphocyte separation. Initially, a numerical model for acoustophoresis was employed and validated against existing experimental results in the literature with a 4% variance, based on the finite element method. Furthermore, in order to ensure the accuracy of the performed simulations, a mesh independency approach was employed for the piezoelectric substrate, alongside an investigation into resonant frequencies across the computational domain. These analyses were conducted to ensure that the results approximate experimental findings more closely and identify the frequency at which the maximum surface displacement occurs, making the results empirically reliable. As a major innovation, a new concentric concave–convex electrode design was introduced, and then the separation distance of targeted particles, as the goal parameter, was studied relative to the geometrical design and acoustofluidic operation parameters of the microfluidic chip. Through numerical analysis, the flow rate ranging from 7 to 14 μl/min and the applied radio frequency signal amplitude ranging from 16 to 26 V were investigated simultaneously. Results demonstrated the microfluidic chip's capability to function effectively across the entire range of voltage and flow rates examined. At the chip's highest operational point, with a flow rate of 13 μl/min and an applied radio frequency signal amplitude of 24 V, particle separation distance reached up to 380 μm. Under similar flow rates, cell conditions, and microchannel length, the particle separation distance has been improved by about 26% as compared with the standard electrode pattern, revealing a significant enhancement in separation efficiency and output purity. Moreover, due to the predominantly radial propagation of the acoustic waves and the expanding acoustic aperture, the resultant standing wave pattern spans a greater length of the microchannel. Assuming a constant injection velocity, this consequently extends the effective exposure time of particles to the acoustic radiation force, allowing for an increase in Stokes drag force. Given that drag force increases with velocity, it enables the opportunity to introduce higher input flow rates and throughput.

Prediction of Time Domain Vibro-Acoustic Response of Conical Shells using Jacobi–Ritz Boundary Element Method

Considering the lack of studies on the transient vibro-acoustic properties of conical shell structures, a Jacobi–Ritz boundary element method for forced vibro-acoustic behaviors of structure is proposed based on the Newmark-β integral method and the Kirchhoff time domain boundary integral equation. Based on the idea of the differential element method and the first-order shear deformation theory (FSDT), the vibro-acoustic model of conical shells is established. The axial and circumferential displacement tolerance functions are expressed using Jacobi polynomials and the Fourier series. The time domain response of the forced vibration of conical shells is calculated based on the Rayleigh–Ritz method and Newmark-β integral method. On this basis, the time domain response of radiated noise is solved based on the Kirchhoff integral equation, and the acoustic radiation characteristics of conical shells from forced vibration are analyzed. Compared with the coupled FEM/BEM method, the numerical results demonstrate the high accuracy and great reliability of this method. Furthermore, the semi-vertex angle, load characteristics, and boundary conditions related to the vibro-acoustic response of conical shells are examined.

Active particle manipulation with valley vortex phononic crystal

The valley vortex state presents an emerging domain in condensed matter physics. As a new information carrier with orbital angular momentum, it demonstrates remarkable ability for reliable, non-contact particle manipulation. In this paper, an acoustic system is constructed to exhibit the acoustic valley state, and traps particles using acoustic radiation force generated by the acoustic valley. Considering temperature effect on the acoustic system, the band structures for temperature fluctuations are discussed. An active controlled method for manipulating particle movement is proposed. Numerical simulations confirm that the particles can be captured by acoustic valley state, and can be repositioned through alterations in temperature, while maintaining a constant excitation frequency.

Assessing the Utility of Acoustic Radiation Force Impulse in the Evaluation of Non-Alcoholic Fatty Liver Disease with Severe Obesity or Steatosis.

Non-alcoholic fatty liver disease (NAFLD) encompasses a heterogeneous spectrum ranging from simple steatosis to fibrosis and cirrhosis. Fibrosis, associated with long-term overall mortality and liver-related events, requires evaluation. Traditionally, liver biopsy has been the gold standard for diagnosing fibrosis. However, its invasive nature, potential complications, and sampling variability limit widespread use. Consequently, various non-invasive tests have been developed as alternatives for diagnosing fibrosis in NAFLD patients. This study aimed to compare the accuracy of non-invasive tests (NITs) and evaluate the diagnostic accuracy of acoustic radiation force impulse (ARFI), one of the point shear wave techniques, compared to conventional methods, assessing its effective role in diagnosis. This is a retrospective study; a total of 136 patients diagnosed with fatty liver disease through ultrasonography were enrolled. The anthropometric data of the patients were collected on the day of admission and blood tests, measurements of ARFI, and a point shear test were conducted using abdominal ultrasound; a biopsy was performed the following day. In addition, we calculated the aspartate aminotransferase-to-platelet ratio index (APRI) index based on four factors (FIB-4) and the NAFLD fibrosis score (NFS). Subsequently, we assessed the diagnostic accuracy of NITs within various subgroups based on the extent of obesity, steatosis, or NAFLD activity score. ARFI has been shown to have the highest diagnostic value among various NITs, with AUROC values of 0.832, 0.794, 0.767, and 0.696 for ARFI, APRI, FIB-4, and NFS, respectively. In the morbidly obese subgroup, the AUROC values of ARFI, APRI, FIB-4, and NFS were 0.805, 0.769, 0.736, and 0.674. In the group with severe steatosis or non-alcoholic steatohepatitis (NASH), the AUROC values were 0.679, 0.596, 0.661, and 0.612, respectively, for severe steatosis and 0.789, 0.696, 0.751, and 0.691, respectively, for NASH. In conclusion, ARFI is not affected by various factors and maintains diagnostic accuracy compared to serum NITs. Therefore, we can recommend ARFI as a valuable diagnostic test to screen for advanced fibrosis in patients with NAFLD.

Digital non-Foster-inspired electronics for broadband impedance matching

Narrow bandwidths are a general bottleneck for applications relying on passive, linear, subwavelength resonators. In the past decades, several efforts have been devoted to overcoming this challenge, broadening the bandwidth of small resonators by the means of analog non-Foster matching networks for radiators, antennas and metamaterials. However, most non-Foster approaches present challenges in terms of tunability, stability and power limitations. Here, by tuning a subwavelength acoustic transducer with digital non-Foster-inspired electronics, we demonstrate five-fold bandwidth enhancement compared to conventional analog non-Foster matching. Long-distance transmission over airborne acoustic channels, with approximately three orders of magnitude increase in power level, validates the performance of the proposed approach. We also demonstrate convenient reconfigurability of our non-Foster-inspired electronics. This implementation provides a viable solution to enhance the bandwidth of sub-wavelength resonance-based systems, extendable to the electromagnetic domain, and enables the practical implementation of airborne and underwater acoustic radiators.

Virtual instrumentation-based data collection and analysis for CNC machining process

Using Computer Numerical Control (CNC) machine tools in manufacturing is crucial for exact processing materials. The quality of the machined product heavily relies on the machine's condition. Therefore, monitoring and assessing the machine's status is essential to ensure product quality and enhance its lifespan. However, due to cost, space, and technical limitations, only a few physical variables, such as acceleration, force, displacement, acoustic radiation, temperature, and flow conditions, can be measured. Efficient transfer and extraction of these data are critical for monitoring machine status using statistical methods or valuable signatures. Traditional measurement instruments are complex and numerous, whereas measurement and analysis systems based on virtual instrumentation technology collect necessary data from sensors and data acquisition cards, meeting the needs of test analysis. Virtual instrumentation utilizes computer hardware resources, modularization hardware, and software systems for data analysis, communication, and operation interface, providing greater versatility, flexibility, compatibility, and repeatability. Previous research has shown successful attempts at developing LabVIEW-based systems for monitoring CNC milling machines and analyzing cutting parameters and forces. This project aims to collect and process data from the CNC machining process. The main objectives include writing a LabVIEW software program, recording data from CNC machine programs using the provided hardware (myRIO) and LabVIEW program, processing the data using MATLAB software, and analyzing and discussing the obtained results. The report consists of four parts, starting with an introduction to the project's background and literature review, followed by a description of the project steps, methods, experiments, and data processing. The processed data graphs will be presented and discussed, and recommendations for future research will be provided before concluding with a study summary.

Acoustofluidic separation of cell-encapsulated droplets based on traveling surface acoustic wave-induced acoustic radiation force

Microscale droplets encapsulating various samples have been widely utilized in droplet microfluidics for single-cell analysis, cell biology, and drug screening. However, the random sample encapsulation within droplets, known as the Poisson distribution, inevitably renders many undesirable empty droplets, whose number far exceeds that of the sample-laden droplets. Precise separation of sample-encapsulated droplets from empty droplets is crucial for improved applicability. The previous methods for droplet separation usually depend on fluorescent, magnetic, or electrical labeling and require upstream detection. Here, we propose an acoustofluidic method for on-chip separation of the sample- encapsulated droplets in a label-free and detection-free manner based on traveling surface acoustic wave (TSAW)-induced acoustic radiation force (ARF). When exposed to an acoustic field, the droplets experience the TSAW-induced ARF, leading to lateral migration in the TSAW direction. The ARF acting on the sample-laden droplets is greater than that on the empty drops due to the additional ARF exerted on the encapsulated samples within the droplets. Our acoustofluidic device demonstrates simultaneous, label-free, detection-free isolation of the drops encapsulating polystyrene microparticles, Thalassiosira eccentrica microalgae and cardiomyocyte cells with high purity and recovery rate. The proposed acoustofluidic approach can open up new horizons for droplet microfluidic applications, especially for single-cell/bead assays.