Acoustic Resonance Research Articles

Controlling acoustic non-Hermitian skin effect via synthetic magnetic fields

Non-Hermitian skin effect (NHSE) is an intrinsic non-Hermitian phenomenon where an extensive number of eigenmodes, called skin modes, are localized at the boundary of a system. Recent theories have suggested that the NHSE can be well-tuned by external fields, opening a route to manipulating wave localization. Here, we experimentally demonstrate the diverse interactions between NHSE and synthetic magnetic fields (SMFs) in coupled acoustic ring resonator lattices. We observe that the NHSE and SMFs can, via different physical mechanisms, compete or synergize, resulting in either the suppression or the creation of NHSE. With the aid of the complex frequency excitation technique, we experimentally observe that SMFs can suppress the NHSE by introducing Landau quantization, causing localization to move toward the bulk. In contrast, we show that the presence of SMF generates topological edge modes in the lattice, which then become corner skin modes by the second-order NHSE. Our results evidence the rich physics and diverse consequences that arise from the interplay of magnetic fields and NHSE, paving the way for actively controlling wave localization.

Electrical Detection of Acoustic Antiferromagnetic Resonance in Compensated Synthetic Antiferromagnets.

Compensated synthetic antiferromagnets (SAFs) stand out as promising candidates to explore various spintronic applications, benefitting from high precession frequency and negligible stray field. High-frequency antiferromagnetic resonance in SAFs, especially the optic mode (OM), is highly desired to attain fast operation speed in antiferromagnetic spintronic devices. SAFs exhibit ferromagnetic configurations above saturation field; however in that case, the intensity of OM is theoretically zero and hard to be detected in well-established microwave resonance experiments. To expose the hidden OM, the exchange symmetry between magnetic layers must be broken, inevitably introducing remanent magnetization. Here, we experimentally demonstrate a feasible method to break the symmetry via surface acoustic waves with the maintenance of compensated SAF structure. By introducing an out-of-plane strain gradient inside the Ir-mediated SAFs, we successfully reveal the hidden OM. Remarkably, the OM intensity can be effectively modulated by controlling strain gradients in SAFs with different thicknesses, confirmed by finite-element simulations. Our findings provide a feasible scheme for detecting the concealed OM, which would trigger future discoveries in magnon-phonon coupling and hybrid quasiparticle systems.

Simultaneous measurement of methane, propane and isobutane using a compact mid-infrared photoacoustic spectrophone

Hydrocarbon gas sensing is a challenging task using laser absorption spectroscopy due to the complex and broad structure of absorption lines. This application requires quick, accurate and highly sensitive detection of hydrocarbon gases concentrations. In this paper, a compact photoacoustic spectrophone was developed to simultaneously measure methane, propane and isobutane. This spectrophone uses wavelength modulation spectroscopy (WMS) with a single acoustic resonator and a single DFB laser emitting at 3368 nm, which greatly reduces the system complexity without using time-division multiplexing technology for multi-gas sensing. Due to the complex and broadband absorption of hydrocarbon gases, a novel signal processing method based on multilinear regression with Ridge regression (MLR-RG) is proposed to reduce the measurement error caused by the nonlinearity of spectra signal. For single gas measurement, the detection limits of methane, propane, and isobutane are determined to be 828 ppb, 419 ppb, and 619 ppb (SNR = 1, integration time = 20 s), respectively. For simultaneous multi-gas sensing in a gaseous mixture, the detection limits of propane and isobutane are determined to be 7 ppb, 68 ppb with an integration time of 860 s, 460 s, respectively. The measurement accuracy of propane and isobutane using MLR-RG is higher than that of ordinary least squares regression and partial least squares regression by 75% and 60%, respectively. The proposed algorithm based on MLR-RG provides a promising approach to process the broad overlapping absorption spectra for accurately retrieving hydrocarbon gases concentrations.

Tunable coupling of a quantum phononic resonator to a transmon qubit via galvanic-contact flip-chip architecture

A hybrid system with tunable coupling between phonons and qubits shows great potential for advancing quantum information processing. In this work, we demonstrate strong and tunable coupling between a surface acoustic wave resonator and a transmon qubit based on the galvanic-contact flip-chip technique. The coupling strength varies from 2π× 7.0 to −2π× 20.6 MHz, which is extracted from different vacuum Rabi oscillation frequencies. The phonon-induced ac Stark shift of the qubit at different coupling strengths is also shown. Our approach offers a good experimental platform for exploring quantum acoustics and hybrid systems.

Investigation of Acoustic Attenuation and Resonances in Lithium‐Ion Batteries Using Ultrasound Spectroscopy

AbstractUltrasound spectroscopy up to 6 MHz is carried out on a 12 Ah Lithium‐ion battery pouch‐cell. The analysis revealed that the attenuation behavior can be effectively described as having an absorption component and a resonance component. It was demonstrated that the absorption can be modeled as a second order polynomial. Two distinct resonances were identified at 2.2 MHz and 4.4 MHz. The first of these resonances shows a significant almost linear reduction in magnitude with increasing state of charge. By smartly choosing the ultrasound interrogation frequency to coincide with this resonance, an almost linear increase by a factor of more than five was measured in the signal amplitude between between state of charge levels of 0 and 100. This could provide the basis for a robust and straightforward state of charge determination method.

Bidirectional microwave-optical transduction based on integration of high-overtone bulk acoustic resonators and photonic circuits

Coherent interconversion between microwave and optical frequencies can serve as both classical and quantum interfaces for computing, communication, and sensing. Here, we present a compact microwave-optical transducer based on monolithic integration of piezoelectric actuators on silicon nitride photonic circuits. Such an actuator couples microwave signals to a high-overtone bulk acoustic resonator defined by the silica cladding of the optical waveguide core, suspended to enhance electromechanical and optomechanical couplings. At room temperature, this triply resonant piezo-optomechanical transducer achieves an off-chip photon number conversion efficiency of 1.6 × 10−5 over a bandwidth of 25 MHz at an input pump power of 21 dBm. The approach is scalable in manufacturing and does not rely on superconducting resonators. As the transduction process is bidirectional, we further demonstrate the synthesis of microwave pulses from a purely optical input. Capable of leveraging multiple acoustic modes for transduction, this platform offers prospects for frequency-multiplexed qubit interconnects and microwave photonics at large.

Effect of phase correction produced by trimming layer on thin-film bulk acoustic resonator

Effect of phase correction produced by trimming layer on thin-film bulk acoustic resonator

Investigation of sorptive interactions between volatile organic compounds and supramolecules at dynamic oscillation using bulk acoustic wave resonator virtual sensor arrays

Supramolecules are considered as promising materials for volatile organic compounds (VOCs) sensing applications. The proper understanding of the sorption process taking place in host-guest interactions is critical in improving the pattern recognition of supramolecules-based sensing arrays. Here, we report a novel approach to investigate the dynamic host-guest recognition process by employing a bulk acoustic wave (BAW) resonator capable of producing multiple oscillation amplitudes and simultaneously recording multiple responses to VOCs. Self-assembled monolayers (SAMs) of β-cyclodextrin (β-CD) were modified on four BAW sensors to demonstrate the gas-surface interactions regarding oscillation amplitude and SAM length. Based on the method, a virtual sensor array (VSA) type electronic nose (e-nose) can be realized by pattern recognition of multiple responses at different oscillation amplitudes of a single sensor. VOCs analysis was realized respectively by using principal component analysis (PCA) for individual VOC identification and linear discriminant analysis (LDA) for VOCs mixtures classification.

Open-fitting hearing aids: a comparative analysis between open behind-the-ear and open completely-in-the-canal instant-fit devices.

Our study aims to assess the open-fitting capabilities and vent properties of traditional open-fitting behind-the-ear (open BTE) hearing aids to instant-fit open-fitting completely-in-the-canal (open CIC) systems. The study analysed data from 40 patients grouped in two groups based on the used hearing aids. Free field pure tone and speech audiometry were performed to obtain the free-field pure tone average and free-field word recognition score (WRS). The matrix sentence test was employed to evaluate the auditory performance and functional outcomes of patients. The Satisfaction with Amplification in Daily Life (SADL) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire were used to assess the personal satisfaction and benefit provided by the hearing aid. Real ear measurements were conducted to objectively evaluate the Real-Ear Unaided Gain (REUG) and Real-Ear Occluded Gain (REOG) of the two groups. For this purpose, six frequency bands (band 1 from 125 to 200Hz, band 2 from 250 to 400Hz, band 3 from 500 to 800Hz, band 4 from 1000 to 1600Hz, band 5 from 2000 to 3150Hz, and band 6 from 4000 to 6300Hz) were defined and compared. Free-field WRS exhibited a significant difference (p-value = 0.004) between open BTE and open CIC, with better results for the open BTE. Matrix test speech reception threshold scores did not differ significantly between groups. No statistical significant difference were observed between APHAB and SADL total scores. Correlation tests revealed a negative correlation between SRT and APHAB scores in the open BTE group, not seen in the open CIC. No statistically significant difference was observed for all bands of REUG values, demonstrating comparability in terms of acoustic resonance of the external auditory canal. Comparing the REOG recorded in the two groups a significant difference was observed for bands 2 through 6. While the average REOG values for bands 5 and 6 were higher in patients with traditional open BTE aids, in contrast, for bands 2, 3, and 4, the REOG values for the open CIC group were higher and statistically significant compared to patients wearing traditional open-fitting BTE hearing aids. Patients with open CIC seem to perform worse in quiet environments compared to noisy ones, as indicated by the free field WRS score. However, the absence of differences in functional performance assessed with the matrix sentence test, and in the psychosocial aspects, makes these devices a good solution for individuals who reject hearing aids due to aesthetic concerns. The differences in terms of real ear measurements, while statistically significant, do not negatively impact overall performance.

Design and development of solidly mounted bulk acoustic wave resonator (SMR)-based ammonia gas sensor

Design and development of solidly mounted bulk acoustic wave resonator (SMR)-based ammonia gas sensor

Research on Underground Positioning Technology for Buried PE Pipes Based on Acoustic Waveguide Resonance

Research on Underground Positioning Technology for Buried PE Pipes Based on Acoustic Waveguide Resonance

A scandium doped aluminum nitride thin film bulk acoustic resonator

Currently, we stand at the forefront of revolutionary advancements in communication technology. The escalating demands of advanced communication necessitate enhanced performance from materials and radio frequency devices. This paper aims to enhance film performance by depositing scandium-doped aluminum nitride (ScAlN) directly onto a Si substrate. Additionally, ScAlN was deposited on SiO2/AlN/Mo functional layers for comparison purposes. The ScAlN directly deposited on Si demonstrated superior performance in terms of crystalline quality and surface roughness, with a full width at half maximum of 1.7° and a roughness of 1.76 nm. Furthermore, a film bulk acoustic resonator (FBAR) based on the ScAlN film directly deposited on Si was successfully fabricated through thin-film transfer, with critical processes achieved via bonding and wet-etching of the substrate. The ScAlN in the fabricated resonator exhibited a favorable c-axis preferred orientation. The resulting ScAlN-based FBAR displayed a quality factor of 429. This study lays the groundwork for exciting opportunities in the development of higher-performance piezoelectric materials and devices.

Acoustic Skyrmionic Mode Coupling and Transferring in a Chain of Subwavelength Metastructures.

Skyrmions, a stable topological vectorial textures characteristic with skyrmionic number, hold promise for advanced applications in information storage and transmission. While the dynamic motion control of skyrmions has been realized with various techniques in magnetics and optics, the manipulation of acoustic skyrmion has not been done. Here, the propagation and control of acoustic skyrmion along a chain of metastructures are shown. In coupled acoustic resonators made with Archimedes spiral channel, the skyrmion hybridization is found giving rise to bonding and antibonding skyrmionic modes. Furthermore, it is experimentally observed that the skyrmionic mode of acoustic velocity field distribution can be robustly transferred covering a long distance and almost no distortion of the skyrmion textures in a chain of metastructures, even if a structure defect is introduced in the travel path. The proposed localized acoustic skyrmionic mode coupling and propagating is expected in future applications for manipulating acoustic information storage and transfer.

Defects and oxygen impurities in ferroelectric wurtzite Al1−xScxN alloys

III-nitrides and related alloys are widely used for optoelectronics and as acoustic resonators. Ferroelectric wurtzite nitrides are of particular interest because of their potential for direct integration with Si and wide bandgap semiconductors and unique polarization switching characteristics; such interest has taken off since the first report of ferroelectric Al1−xScxN alloys. However, the coercive fields needed to switch polarization are on the order of MV/cm, which are 1–2 orders of magnitude larger than oxide perovskite ferroelectrics. Atomic-scale point defects are known to impact the dielectric properties, including breakdown fields and leakage currents, as well as ferroelectric switching. However, very little is known about the native defects and impurities in Al1−xScxN and their effect on the dielectric and ferroelectric properties. In this study, we use first-principles calculations to determine the formation energetics of native defects and unintentional oxygen incorporation and their effects on the polarization switching barriers in Al1−xScxN alloys. We find that nitrogen vacancies are the dominant native defects, and unintentional oxygen incorporation on the nitrogen site is present in high concentrations. They introduce multiple mid-gap states that can lead to premature dielectric breakdown and increased temperature-activated leakage currents in ferroelectrics. We also find that nitrogen vacancy and substitutional oxygen reduce the switching barrier in Al1−xScxN at low Sc compositions. The effect is minimal or even negative (increases barrier) at higher Sc compositions. Unintentional defects are generally considered to adversely affect ferroelectric properties, but our findings reveal that controlled introduction of point defects by tuning synthesis conditions can instead benefit polarization switching in ferroelectric Al1−xScxN at certain compositions.

Characterizing Femtosecond Laser Tagging Performance With A 1030 Nm Yb:KGW Laser And Application To Continuous 50 KHz Velocimetry

This paper presents a comprehensive evaluation of unseeded Femtosecond Laser Electronic Excitation Tagging (FLEET) using a 1030 nm Yb:KGW femtosecond laser. In the first part of this work, fundamental studies were conducted in a vacuum chamber to assess the fluorescence process in dry air and nitrogen. Specifically, the effects of pressure, pulse energy, and focal length on the temporal decay of the nitrogen first and second positive band emission are quantified and reported. The results show similar trends to previous reports of FLEET emission behavior at other visible and near infra-red excitation wavelengths, indicating that the same fundamental fluorescence mechanism occurs after 1030 nm excitation. In the second part of this work, we explore the application of 1030 nm FLEET to continuous high-speed velocimetry in an under-expanded laboratory jet. Unseeded velocity measurements at 50 kHz in air were acquired at several points in the flow using burst gating of a high-speed intensifier. Frequency domain analysis of over 50,000 time-resolved measurements show strong periodic fluctuations near 8 kHz due to an acoustic resonance near the jet exit. Analysis of the streamwise velocity autocorrelation is shown to provide a means to separate uncorrelated random measurement error from true flow fluctuations. These results establish a first demonstration of continuous, high-speed FLEET measurements at 1030 nm and provides foundational data to inform future applications of this unseeded velocimetry technique in turbulent high-speed flows.

Heterogeneous Integration of Acoustic Microextraction with an Optoelectronic Sensor on Glass for Nucleic Acid Testing.

Lab-on-a-chip systems (LOCs), characterized by their high sensitivity, low sample consumption, and portability, have significantly advanced the field of on-site testing. Despite the evolution of integrated LOCs from qualitative to quantitative analyses, on-chip full integration of sample preparation, purification, and multiplexed detection remains a challenge. Here, we propose a strategy for the heterogeneous integration of a set of complementary metal oxide semiconductor-compatible devices including acoustic resonator, thin-film resistors, and temperature/photosensors as a new type of LOC for nucleic acid testing (NAT). Programmed acoustic streaming-based particles and fluid manipulations largely simplify the nucleic acid extraction process including cell lysis, nucleic acid capture, and elution. The design of the acoustic microextraction module and extraction process was thoroughly studied. Benefitted by the microelectromechanical system approach, the conventional mechanical actions and complex flow control are avoided, which enables a compact hand-held NAT instrument without complicated peripherals. Validation experiments conducted on plasma-harboring mutations in the epidermal growth factor receptor (EGFR) gene confirmed the robustness of the system, achieving an impressive nucleic acid (NA) extraction efficiency of approximately 90% within 5 min and a limit of detection of the target NA in the plasma of 1 copy/μL.

A Flexural Ultrasonic Transducer for Inducing Acoustic Cavitation on Material Surfaces

Abstract Purpose This paper proposes a flexural ultrasonic transducer specifically designed for surface treatment of materials with delicate surfaces such as skin by acoustic cavitation at low frequencies. The goal of this preliminary study is to assess the resonance frequencies and the output sound pressure of the proposed transducer and confirm generation of acoustic cavitation on the surface of an artificial skin phantom. Methods A transducer prototype was designed based on structural-acoustic simulation and fabricated. The proposed design employs a concave-shaped acoustic resonator with a spherical cavity, which is driven by flexural vibration of a piezoelectric ceramic disk actuator. The transducer prototype has compact dimensions of 15 mm in diameter and 8 mm in axial length, working at frequencies around flexural vibration modes of the piezoelectric disk with a thickness of 1 mm. Results The maximum sound pressure amplitude reached 125 kPa with an input voltage amplitude of 10 V at the second resonance frequency of 167 kHz, where the third axisymmetric eigenmode was excited. Despite enhancing the maximum pressure, the sound pressure outside the resonator attenuates because the near-field distance of the irradiated sound wave is smaller than the height of the resonator. This implies that the proposed method provides the cavitation effect on material surfaces, possibly minimizing the side effect of ultrasound irradiation on the underlying structure. Cavitation generation on a urethane gel surface was directly observed by using a high-speed video camera. Conclusion We confirmed that acoustic cavitation was generated and propelled to the target surface. It concludes that ultrasound irradiation using the proposed ultrasonic transducer could be a promising alternative for effective and safe ultrasound treatment of material surfaces.

All-oxide thin-film varactors with SrMoO[formula omitted]-bottom electrodes and Mn/Ni-doped BST for sub-6 GHz applications

This paper presents a comprehensive study and performance analysis of all-oxide thin-film Au/Pt/Ba0.5Sr0.5TiO3/SrMoO3 varactors with 100nm Ba0.5Sr0.5TiO3 (BST) tunable dielectric layers doped with 1%, 3% and 5% of Mn and Ni grown epitaxially on a 600nm SrMoO3 bottom electrode. Performance parameters such as tunability, quality factor, figure-of-merit, leakage current and acoustic resonances of the varactors are investigated. The investigation covers frequencies up to 6GHz and a broad temperature range from −40∘ to 80∘, using biasing field strengths of up to ± 100V/μm, in order to evaluate the feasibility and the performances of BST-doped all-oxide varactors for sub-6 GHz applications. Results confirm the anticipated advantages of Mn and Ni doping: a substantial reduction in leakage current along with an increase in quality factor, however, at the cost of reduced tunability. The observed acoustic resonances are shifted towards higher frequencies as compared to those for varactors with undoped BST, which implies in a larger frequency operating range for doped all-oxide varactors. In addition, the amplitudes of the acoustic resonances decline with doping. Moreover, they can be effectively suppressed for thinner BST layers, which has been proved exemplarily for a varactor with a 25nm Mn-doped BST layer and a tunability of 55 %, requiring an ultimately low tuning voltage of only 2.9V.

Effect of Si substrate conductivity on surface acoustic wave resonator

A surface acoustic wave (SAW) filter’s bandwidth and quality are determined by its resonators’ electromechanical coupling coefficient (k2) and impedance ratio (IR). Research commonly focuses on the effects of piezoelectric material and cutting direction on these parameters. This paper investigates the effect of the conductivity of the Si substrate on k2 and IR through finite element method (FEM) simulations. A new model based on the modified Butterworth-van-Dyke (MBVD) model is presented. This new model takes into account the substrate parasitic capacitance and resistance to predict resonator performance on low resistivity (LR) Si piezoelectric on insulator (POI) substrates. Both high resistivity (HR) Si and LR-Si are utilized to fabricate POI SAW resonators, which are subsequently tested. The high conductivity of the Si support layer leads to a decrease in both k2 and IR. By employing Si substrates with different resistances during fabrication, it becomes possible to manufacture resonators with varying k2 values, thus meeting diverse bandwidth requirements for filters.

Physics-informed neural network for acoustic resonance analysis in a one-dimensional acoustic tube

This study devised a physics-informed neural network (PINN) framework to solve the wave equation for acoustic resonance analysis. The proposed analytical model, ResoNet, minimizes the loss function for periodic solutions and conventional PINN loss functions, thereby effectively using the function approximation capability of neural networks while performing resonance analysis. Additionally, it can be easily applied to inverse problems. The resonance in a one-dimensional acoustic tube, and the effectiveness of the proposed method was validated through the forward and inverse analyses of the wave equation with energy-loss terms. In the forward analysis, the applicability of PINN to the resonance problem was evaluated via comparison with the finite-difference method. The inverse analysis, which included identifying the energy loss term in the wave equation and design optimization of the acoustic tube, was performed with good accuracy.