Propagation Direction Of Acoustic Wave Research Articles

Tunable Acoustic Tweezer System for Precise Three-Dimensional Particle Manipulation

This study introduces a tunable acoustic tweezer system designed for precise three-dimensional particle trapping and manipulation. The system utilizes a dual-liquid-layer acoustic lens, which enables the dynamic control of the focal length through the adjustable curvature of a latex membrane. This tunability is essential for generating the acoustic forces necessary for effective manipulation of particles, particularly along the direction of acoustic wave propagation (z-axis). Experiments conducted with spherical particles as small as 1.5 mm in diameter demonstrated the system’s capability for stable trapping and manipulation. Performance was rigorously evaluated through both z-axis and 3D manipulation tests. In the z-axis experiments, the system achieved a manipulation range of 33.4–53.4 mm, with a root-mean-square error and standard deviation of 0.044 ± 0.045 mm, which highlights its precision. Further, the 3D manipulation experiments showed that particles could be accurately guided along complex paths, including multilayer rectangular and helical trajectories, with minimal deviation. A visual feedback-based particle navigation system significantly enhanced positional accuracy, reducing errors relative to open-loop control. These results confirm that the tunable acoustic tweezer system is a robust tool for applications requiring precise control of particles with diameter of 1.5 mm in three-dimensional environments. Considering its ability to dynamically adjust the focal point and maintain stable trapping, this system is well suited for tasks demanding high precision, such as targeted particle delivery and other applications involving advanced material manipulation.

Evaluation of the Tellurium Dioxide Crystal Shear Acoustic Wave Attenuation at 40-140 MHz Frequency.

The attenuation of slow shear acoustic waves in the (110) plane of tellurium dioxide (TeO2) crystals was investigated. The strong acoustic anisotropy of TeO2 crystals results in a non-uniform acoustic power distribution, which can introduce errors in conventional acousto-optic testing methods. In this study, we propose a general method to measure the acoustic power distribution along the propagation direction of acoustic waves in non-collinear acousto-optic tunable filters (AOTFs). Additionally, we analyze the errors introduced by the non-uniform acoustic field resulting from strong acoustic anisotropy in acousto-optic testing methods. The measurements were carried out for a crystal cutoff angle of 6.5° from the [110] axis, for the ultrasound frequency range from 40 to 140 MHz. The attenuation coefficients were determined and their quadratic dependence on ultrasound frequency was confirmed.

Enhanced Radiation Efficiency by Resonant Coupling in a Large Bandwidth Magnetoelectric Antenna

AbstractMagnetoelectric (ME) antennas hold the potential for significantly advancing miniaturization in radio frequency devices due to their compact size. However, critical hurdles still remain in ME antennas including low radiation efficiency and narrow bandwidth, which prevent them from seeing widespread use. Here, by sweeping the magnetic field to reach a resonant coupling, a significant enhancement in radiation efficiency by 70.95 ± 6.4% in a broad bandwidth ME antenna with 80 MHz is achieved as well as the far‐field radiation patterns are changed compared with that via non‐resonant coupling. The enhancement depends on the relative orientation between the magnetization and surface acoustic wave propagation direction which is dominated by the symmetry of the driving field induced by shear strain. A larger enhancement occurs when the magnetic field along hard axis of Ni due to the matching helicity and larger strain compared with easy axis scenario. This work demonstrates an innovative methodology that significantly enhances the radiation and reception efficiency in ME antennas, which may provide ideas for subsequent applications in communication antennas and magnetic sensors.

Three-dimensional modeling and experimentation of microfluidic devices driven by surface acoustic wave

Surface acoustic wave (SAW) technology is proving to be an effective tool for manipulating micro-nano particles. In this paper, we present a fully-coupled 3D model of standing SAW acoustofluidic devices for obtaining particle motion. The “improved limiting velocity method” (ILVM) was used to investigate the distribution of acoustic pressure and acoustic streaming in microchannel. The results show that the distribution of acoustic pressure and acoustic streaming on the piezoelectric substrate surface perpendicular to the acoustic wave propagation direction is inhomogeneous. The motion of micro-particles with diameters of 0.5-, 5-, and 10 μm is then simulated to investigate the interaction of acoustic radiation force and drag force caused by pressure and acoustic streaming. We demonstrate that micro and nanoparticles can move in three dimensions when acoustic radiation force and acoustic streaming interact. This result and method are critical for designing SAW microfluidic chips and controlling particle motion precisely.

The impact of ultrasound on Janus capsules at gel-liquid interface

Ultrasound-responsive Janus capsules gain increasing recognition in the scientific world due to the wide spectrum of their potential applications. Spherical structures with the heterogeneous shells composed of two kinds of fused polymeric microparticles can be particularly useful when the cargo should be released in a strictly controlled manner. Distinct physical properties of individual hemispheres have a significant impact on the course of the payload release process. In this paper we deal with the problem of the influence of high-frequency and low intensity ultrasound on the behaviour of Janus capsules placed at the gel-liquid interface. Such a boundary between two phases can simulate the natural barriers occurring for example in biological systems. We show that 1 MHz acoustic waves are able to liberate the content from Janus capsule and push the freed liquid cargo through the interface so that it penetrates into the gel medium. We demonstrate that the size of the Janus capsule and, above all, its orientation at the interface in relation to the direction of acoustic wave propagation, are the key factors determining the progress of payload release and its transfer to the gel medium. Shell region that is mechanically weaker tends to break faster, which defines the initial path of payload release. Presented results contribute to a better understanding of physical phenomena occurring during the interaction of ultrasound with particle capsules. They can also become a source of inspiration not only for further experimental research, but also for theoretical analysis.

Flexible thin-film acoustic wave devices with off-axis bending characteristics for multisensing applications

Flexible surface acoustic wave (SAW) devices have recently attracted tremendous attention for their widespread application in sensing and microfluidics. However, for these applications, SAW devices often need to be bent into off-axis deformations between the acoustic wave propagation direction and bending direction. Currently, there are few studies on this topic, and the bending mechanisms during off-axis bending deformations have remained unexplored for multisensing applications. Herein, we fabricated aluminum nitride (AlN) flexible SAW devices by using high-quality AlN films deposited on flexible glass substrates and systematically investigated their complex deformation behaviors. A theoretical model was first developed using coupling wave equations and the boundary condition method to analyze the characteristics of the device with bending and off-axis deformation under elastic strains. The relationships between the frequency shifts of the SAW device and the bending strain and off-axis angle were obtained, and the results were identical to those from the theoretical calculations. Finally, we performed proof-of-concept demonstrations of its multisensing potential by monitoring human wrist movements at various off-axis angles and detecting UV light intensities on a curved surface, thus paving the way for the application of versatile flexible electronics.

Large dynamic-range fiber Bragg grating sensor system for acoustic emission detection.

A distributed feedback (DFB) fiber laser and fiber Bragg gratings (FBGs) are configured to demodulate the wavelength shifts of FBG dynamic strain sensors. The FBG sensors act as sensing units to detect the dynamic strain and the demodulators while the DFB fiber laser only acts as a narrow-linewidth light source. As the reflective spectrum of the FBG sensor changes due to dynamic strains, the output is subsequently converted into a corresponding intensity change and detected directly by a photodetector. The 0.2 nm linewidth FBG sensor can detect the impact signal with a frequency of up to 300 kHz with a maximum of 29.17 µɛ, which is comparable with the detecting result of the piezoelectric transducer sensor. Moreover, the directional response of the FBG sensor is maximized when the direction of acoustic wave propagation is parallel to the optical fiber. The relation between the sensitivity and the FBG spectrum linewidth is presented, and the detectable strain range versus different FBG linewidths is also discussed.

Численное моделирование распространения акустического сигнала в подводном звуковом канале

Object and purpose of research. The progress in numerical simulation methods significantly widens the capabilities of theoretical analysis in the tasks requiring extensive calculations and input data sets, like sound propagation at sea. This paper discusses the feasibility of a numerical model describing the physics of acoustic signal propagation in a deep-water channel. Materials and methods. Acoustic signal calculation is performed as per the ray-path theory with a numerical model taking into account depth-wise variations of sound velocity and seabed parameters. Main results. It was shown that depending on the vertical distribution of sound speed, the source depth and distance, the acoustic wave propagation direction can change over significant range of angles the in vertical plane. In this regard it is advisable to calculate the real target force of an object of complex geometry not only from heading angle in horizontal plane but also in terms of the possible range of angles in the vertical plane. Conclusion. Model-analyzed angles range of long-range wave propagation may be used for change estimation of object target force characteristics. Practical significance of the study lies in improving the methods of calculation of the real target force of complex shape objects in terms of state-of the art capabilities of simulating the propagation of acoustic signals conditions in the ocean.

Detecting of non-uniformly distributed loads with SAW sensors using a two-dimensional segmentation method

To accurately calculate the response of surface acoustic wave sensors with non-uniformly distributed loads, a two-dimensional segmentation method suitable for various load distribution patterns was established with the idea of channelization. In this method, the sensitive area of the sensor was divided into several channels in the direction of the aperture, and each channel was cut apart into several cells along the direction of acoustic wave propagation. Finally, the two-dimensional analysis of the non-uniform distributed load was completed since each cell was analyzed and cascaded. A Rayleigh surface acoustic wave (R-SAW) sensor was used to simulate and experiment in this paper. The results showed that the responses of SAW sensors under loads with the non-uniform distributions were simulated accurately by using a two-dimensional segmentation method.

Modulating optical properties of Lithium Niobate through acoustic stress

Optical index modulation in Z-X Lithium Niobate slab through acoustic stress is theoretically studied. To generate acoustic stress, fundamental symmetric Lamb mode is excited in the slab. A periodic disturbance of period 858 nm in 500 nm thick slab is noticed when 5 GHz frequency Lamb wave mode is used. The displacement field pattern caused by 5 GHz acoustic disturbance is then estimated using potential techniques and applied to photo-elastic relations. Theoretical calculation reveals that the disturbance modulates optical index sinusoidally, with alternate decrement and increment in optical index around the unperturbed value. The maximum observed variation was found along the direction of acoustic wave propagation is of order of 1.5 percent.

Multiple selective absorption peaks of acoustic waves in a one-dimensional composite

We investigate a one-dimensional composite with a very low loss coefficient and find that multiple selective absorption peaks reach close to 100% absorption of incident acoustic waves when the acoustic waves propagate through this system. Especially, the unidirectional absorption is demonstrated when the propagation direction of acoustic waves is reversed. These high absorptions stem from the excitations of the strong resonances, which depend on not only the low loss in this composite but also the huge impedance mismatch at the outgoing interface. To further investigate those selective absorption, we construct an equivalent structural model, and our calculations show that these absorption peaks have the extraordinary response to the imaginary part of the effective mass density and bulk modulus. The results exhibit that the imaginary part of the effective mass density and bulk modulus at the frequencies of the absorption peaks abruptly appear, in the meanwhile the real part of those become zero. Based on these theoretical results, an unidirectional absorption device with multiple selection of frequencies can be designed.

Measurements of ion velocity and wave propagation in a hollow cathode plume

The mechanism responsible for the production of energetic ions in the plume of hollow cathodes for electric propulsion is still an open issue. These ions are of concern to cathode and thruster lifetime, particularly for cathodes operating at high (>20 A) discharge currents. Recent theoretical and experimental investigations suggest that there is a correlation between ion energy gain and ion acoustic turbulence. In this paper we present measurements of the evolution of the ion velocity distribution function in the near plume of a 100 A-class hollow cathode, operated in a regime in which the dominant mode is ion acoustic turbulence. Ion flow and thermal properties were related to measurements of the background plasma, fluctuation spectra, and dispersion relations obtained from an array of Langmuir probes. We found ions to flow outward from the cathode and accelerate downstream, to supersonic speeds, approximately aligned with the acoustic wave group velocity vectors. The directions of the ion flow and wave propagation were similar for a range of discharge currents and mass flow rates in the jet region of the plume. One operating condition showed a significant temperature increase, also in the direction of acoustic wave propagation, corresponding to the highest wave energy condition. These results are interpreted in the context of ion acoustic turbulence as a contributing mechanism for ion energy gain.

Enhanced performance of AlN SAW devices with wave propagation along the 〈11−20〉 direction on c-plane sapphire substrate

This paper investigates the effect of acoustic wave propagation direction along the a-direction (〈11−20〉) and m-direction (〈1−100〉) on the frequency responses of c-plane AlN based surface acoustic wave (SAW) devices systematically. The experimental results indicate that the resonant frequency (), quality factor (Q), electromechanical coupling coefficient (), insertion loss and out-of-band rejection can be improved for the a-direction compared with the m-direction of an AlN based SAW resonator on sapphire. The Q is 1347 for a one-port SAW resonator along the a-direction, and the minimum insertion loss is 8.71 dB for a two-port SAW resonator along the a-direction. The insertion loss is 3.23 dB lower for the a-direction compared to the m-direction of the AlN film, which may be attributed to the larger acoustic power flow density. The is 45% higher for the a-direction compared to the m-direction of the AlN film, which may be attributed to the larger elastic constant. In addition, our finite element model simulation results reveal the C11 and C44 for the m-direction are 345 GPa and 102 GPa, while C11 and C44 for the a-direction is increased to 429 GPa and 128 GPa, respectively. Our work demonstrates that the a-direction is better than the m-direction of the AlN film for high performance SAW device applications.

Experimental Study of Multilayer Piezo-magnetic SAW Delay Line for Magnetic Sensor

This communication describes an experimental study of multilayer piezo-magnetic acoustic wave devices used as sensors of external magnetic fields applied in plane, parallel or perpendicular to the direction of the acoustic wave propagation direction. The considered device consists of a layered structure Mag/ZnO/IDT/LNY-128, Mag being the sensitive magnetoelastic layer. Two magnetoelastic films are investigated as sensitive layers: Ni and CoFeB. Their sensitivities to the magnetic field intensity and direction are measured and compared.

Ultrasonic Beam Simulation of Austenitic Stainless Steel Pipeline Welding Cladding

Austenitic stainless steel shows clear acoustic anisotropy. How to detect and evaluate the material becomes research difficulty and popular problem in acoustic detection field. In the paper, Civa software is applied for simulating ultrasonic wave propagation in austenitic stainless steel cladding layer. The influence of included angle between acoustic wave propagation direction and crystal axis on acoustic wave propagation is studied. The study results show that: the focusing property is good when the included angle is 30°-45°, which is beneficial for ultrasonic testing of cladding layer. When the included angle is greater than 70° or so, actual propagation path of acoustic wave and propagation direction of acoustic wave have certain deviation angle with poor acoustic wave focusing property and rapid acoustic attenuation speed, which is not conducive to acoustic detection of cladding layer.

Method of extreme surfaces for optimizing geometry of acousto-optic interactions in crystalline materials: Example of LiNbO3 crystals

We suggest a method for optimizing geometry of acousto-optic (AO) interactions in anisotropic crystalline materials. Within the framework of this method, one gets global maximums of AO figure of merit M2 and their spatial orientations, proceeding from so-called “extreme” indicative surfaces, which are obtained after finding such an acoustic wave propagation direction that maximizes the M2 parameter for each propagation direction of the incident electromagnetic wave. The method improves earlier indicative surface-based techniques in several aspects, particularly in properly accounting for the momentum conservation condition for the AO diffraction, and yields a higher accuracy in assessing spatial anisotropy of the AO effect. We have constructed the extreme surfaces of LiNbO3 crystals for all possible cases, including those of isotropic/anisotropic AO diffractions and longitudinal/transverse acoustic waves. The anisotropy of the AO figure of merit for LiNbO3 is analyzed for the acoustic frequencies 0.01–2.0 GHz and the light wavelengths 405–1444 nm. The absolute M2 maximums refer to ‘indirect crystal cuts' and are equal to 26.3 × 10−15 s3/kg at 2 GHz and 405 nm, and 15.4 × 10−15 s3/kg at 0.4 GHz and 1444 nm.

Lamb Waves Propagation along 3C-SiC/AlN Membranes for Application in Temperature-Compensated, High-Sensitivity Gravimetric Sensors

The propagation of the fundamental quasi-symmetric Lamb mode S0 travelling along 3C-SiC/c-AlN composite plates is theoretically studied with respect to the AlN and SiC film thickness, the acoustic wave propagation direction and the electrical boundary conditions. The temperature effects on the phase velocity have been considered for four AlN/SiC-based electroacoustic coupling configurations, specifically addressing the design of temperature-compensated, enhanced-coupling, GHz-range electroacoustic devices. The gravimetric sensitivity and resolution of the four temperature-stable SiC/AlN composite structures are theoretically investigated with respect to both the AlN and SiC sensing surface. The SiC/AlN-based sensor performances are compared to those of surface acoustic waves and Lamb S0 mode mass sensors implemented on bulk conventional piezoelectric materials and on thin suspended membranes.

Nonlinear nonclassical acoustic method for detecting the location of cracks

In this study, a new nonlinear acoustic method that makes full use of the sensitivity of higher harmonics caused by internal microcracks is proposed to locate multiple cracks in a one-dimensional bar. The tested bar was coupled with an acoustic emitter, the frequency used by the transducer is the eigenfrequency of the bar, and the boundary of the emitter can be treated as free. A mass load was added to the other end of the bar to provide an asymmetrical boundary condition. The receiver was scanned along the propagation direction of acoustic wave. The relationships between the amplitude, the phase of the harmonics, and the positions of the cracks can be used to locate multiple cracks in the bar. The higher harmonic frequencies induced due to crack nonlinearity are different from the eigenfrequencies of the bar. This creates an amplitude difference in the vibration on each side of the cracks and can be used to locate multiple cracks in a one-dimensional bar. Numerical calculations were carried out to verify the method and possible approaches to improve the accuracy of this method are discussed.

Unique fingering instabilities and soliton-like wave propagation in thin acoustowetting films

Acoustic-fluid interactions not only has had a long history but has recently experienced renewed scrutiny because of their vast potential for microscale fluid and particle manipulation. Here we unravel a fascinating and anomalous ensemble of dynamic 'acoustowetting' phenomena in which a thin film drawn from a sessile drop first spreads in opposition to the acoustic wave propagation direction. The advancing film front then exhibits fingering instabilities akin to classical viscous fingering, but arising through a different and novel mechanism: transverse Fresnel diffraction of the underlying acoustic wave. Peculiar 'soliton-like' wave pulses are observed to grow above these fingers, which, on reaching a critical size, translate away along the wave propagation direction. By elucidating the complex hydrodynamics underpinning the spreading, and associated flow reversal and instability phenomena, we offer insight into the possibility of acoustically controlling fast and uniform film spreading, constituting a flexible and powerful alternative for microfluidic transport.

Ultrasonic imaging of an object at the presence of Fourier and non-Fourier transformation in the transmitted through the object acoustic field

A metal object is computer visualized by registration of the amplitudes of the transmitted through the object short acoustic pulses. The pulses are separated by time, because of the presence of holes and internal compact components in the longitudinal section (structure along the propagation direction of acoustic wave). The acoustic field transmitted through the object is composited from a field presenting Fourier transformation of the hole shape and field, transmitted through the metal components in the longitudinal section of the object. A computer Fourier transformation of the digital data of the amplitude fields transmitted through the object components is performed instead of converging lens. The Fourier series of the object obtained as digital data after the transformation is multiplied with a term, describing the angle distribution of the field on spatial frequencies. The reconstruction of the image of the metal components is performed by reverse transformation, i.e. summing up in all spatial frequencies. 3D visualization of the transmitted through the hole acoustic field determines the hole geometry (circular, square, rectangular). It is shown that at the transmission of a short acoustic pulse through the components with different thicknesses and holes, presenting Fourier and non-Fourier transformation can be registered separately in contrast to the optics.