Detection Of Surface Acoustic Waves Research Articles

On-chip stimulated Brillouin scattering via surface acoustic waves

Surface acoustic wave devices are ubiquitously used for signal processing and filtering, as well as mechanical, chemical, and biological sensing and show promise as quantum transducers. While surface acoustic waves (SAWs) are primarily excited and driven using electromechanical coupling and interdigital transducers, there is a strong desire for novel methods that enable the coherent excitation and detection of SAWs all-optically interfacing with photonic integrated circuits. In this work, we numerically model and experimentally demonstrate SAW excitation in integrated photonic waveguides made from GeAsSe glass via backward stimulated Brillouin scattering (SBS). We measure a Brillouin gain coefficient of 203 W−1 m−1 for the surface acoustic resonance at 3.81 GHz, with a linewidth narrowed to 20 MHz. Experimental access to this new regime of SBS not only opens up opportunities for novel on-chip sensing applications by harnessing the waveguide surface but also paves the way for strong Brillouin interactions in materials lacking sufficient acoustic guidance in the waveguide core, as well as the excitation of SAWs in non-piezoelectric materials.

Rapid point-of-care breath test predicts breast cancer and abnormal mammograms in symptomatic women

Previous studies have reported volatile organic compounds (VOCs) in the breath as biomarkers of breast cancer. These biomarkers may be derived from cancer-associated fibroblasts, in which oxidative stress degrades polyunsaturated fatty acids to volatile alkanes and methylated alkane derivatives that are excreted in the breath. We evaluated a rapid point-of-care test for breath VOC biomarkers as predictors of breast cancer and abnormal mammograms.&#xD;Methods: We studied 593 women aged ≥ 18 yr referred to three sites for mammography for a symptomatic breast-related concern (e.g. breast mass, nipple discharge). A rapid point-of-care breath testing system collected and concentrated alveolar breath VOCs on a sorbent trap and analyzed them with gas chromatography and surface acoustic wave detection in < 6 min. Breath VOC chromatograms were randomly assigned to a training set or to a validation set. Monte Carlo analysis identified significant breath VOC biomarkers of breast cancer and abnormal mammograms in the training set, and these biomarkers were incorporated into a multivariate algorithm to predict disease in the validation set. &#xD;Results: Prediction of breast cancer: 50 women had biopsy-proven breast cancer (invasive cancer 41, ductal non-invasive cancer 9)&#xD;Unsplit data set: Breath VOCs identified breast cancer with 83% accuracy (area under curve of receiver operating characteristic), 82% sensitivity and 77.1% specificity.&#xD;Split data sets: Training set breath VOCs identified breast cancer with 80.3% accuracy, 84% sensitivity and 74.3% specificity. Corresponding values in the validation set were 68%% accuracy, 72.4% sensitivity and 61.5% specificity.&#xD;Prediction of BIRADS 4 and 5 mammograms (versus BIRADS 1, 2 and 3): &#xD;Unsplit data set: Breath VOCs identified abnormal mammograms with 76.2% accuracy.&#xD;Split data sets: Breath VOCs identified abnormal mammograms with 74.2% accuracy, 73.3% sensitivity and 60% specificity. Corresponding values in the validation set were 60.5% accuracy, 64.2% sensitivity and 51% specificity.&#xD;Conclusions: A rapid point-of-care test for breath VOC biomarkers predicted risk of breast cancer and abnormal mammograms in women with breast-related symptoms.&#xD;&#xD.

Detection of Water Surface Acoustic Waves Using Sinusoidal Phase Modulation Interferometer and Prenormalized PGC-Arctan Algorithm

A sinusoidal phase modulation laser interferometer is proposed to detect water surface acoustic waves excited by underwater acoustic radiation, and an improved PGC-Arctan demodulation algorithm that combines prenormalization and Lissajous ellipse fitting is proposed to demodulate detection signals. In this paper, the effects of phase modulation depth, carrier phase delay, and interference signal visibility on the Lissajous figure formed by quadrature interference components are analyzed. The demodulation algorithm first uses the amplitudes of multiple Fourier spectral components of an interference signal to calculate the phase modulation depth C, and calculation of the carrier phase delay Vc is achieved through the introduction of a quadrature carrier signal. Then, certain coefficients regarding C and Vc are constructed for prenormalization of the two quadrature interference signal components to eliminate the local nonuniform widening phenomenon of Lissajous ellipse. Next, the outer and the inner contours are extracted from a uniformly widened Lissajous ellipse resulting from light intensity disturbance, and the axial ratio of the ellipse is obtained, which is used to correct the ratio of the quadrature interference signal to eliminate the effect of filter gain coefficients. At last, through the combination of an Arctan algorithm and a phase-unwrapping algorithm, high-precision demodulation of the interference signal is realized. A sinusoidal phase modulation interferometer was set up to detect water surface acoustic waves, and a series of detection experiments were carried out. The experiment results show that the detection method and demodulation algorithm described in this paper can accurately realize the measurement of weak water surface acoustic waves. The proposed algorithm shows less distortion in demodulation results, and its signal-to-noise distortion ratio is less than 20 dB at 500 Hz, which is significantly better than traditional algorithms. The experimental results demonstrate the effectiveness and accuracy of water surface acoustic wave detection using sinusoidal phase modulation interferometer.

In situ monitoring of lithium electrodeposition using transient grating spectroscopy

Mechanisms of lithium electrodeposition, which overwhelmingly affect lithium metal battery performance and safety, remain insufficiently understood due to its electrochemical complexity. Novel, nondestructive, and in situ techniques to probe electrochemical interfaces during lithium electrodeposition are highly desirable. In this work, we demonstrate the capability of transient grating spectroscopy to monitor lithium electrodeposition at the micrometer scale by generating and detecting surface acoustic waves that sensitively interact with the deposited lithium. Specifically, we show that the evolution of the frequency, velocity, and damping rate of the surface acoustic waves strongly correlates with the lithium nucleation and growth process. Our work illustrates the sensitivity of high-frequency surface acoustic waves to micrometer scale changes in electrochemical cells and establishes transient grating spectroscopy as a versatile platform for future in situ investigation of electrochemical interfaces.

Water Surface Acoustic Wave Detection by a Millimeter Wave Radar

Feature extraction and recognition of underwater targets are important in military and civilian areas. This paper studied water surface acoustic wave (WSAW) detection by a millimeter wave (mmWave) radar. The mmWave-based endpoint detection method of the WSAW was introduced. Simulated results show that the continuous wavelet transform (CWT) method has a better detection performance. A 77 GHz large aperture antenna mmWave radar sensor and an underwater acoustic transmitter have been applied to conduct laboratory experiments. Still water surface experimental results verify that the CWT method has better detection capability, and the mmWave radar can accurately detect even 155 nm WSAW. Wavy water surface experimental results demonstrate the ability of the mmWave radar to analyze the time-frequency feature of the weak WSAW signal. These works indicate the potential of mmWave radar for the cross-medium detection and recognition of underwater targets.

Effect of Carrier Gas on Sensitivity of Surface Acoustic Wave Detector

Enhancement of sensitivity is a hot pursuit for every kind of sensor/detector. While many methods are exploited for various sensors/detectors for this, the methods are specific in nature for the technology involved. This article discusses a novel study where enhancement of sensitivity, specific to a Surface Acoustic Wave (SAW) device used as a Gas Chromatographic (GC) detector is achieved by using a proper carrier gas. With an ultimate aim of implementing the outcome on SAW-GC based, handheld, Chemical Warfare Agent (CWA) Electronic-Nose vapour detector being developed at our laboratory, four different carrier gases i.e. Hydrogen, Helium, Nitrogen and Zero air were subjected to the scrutiny for its impact on sensitivity. Detection of a CWA simulant, 2-Chloro-Ethyl-Ethyl-Sulfide (CEES), 1,5-Dichloropentane (DCP) simulating Sulphur Mustard (H Agent), Di-methylmethyl phosphonate (DMMP), Diethyl cyanophosphonate (DECP), Triethyl pohosphate (TEP) simulating G-Agents along with three Volatile Organic Compounds (VOCs) i.e. Methanol, Toluene and Xylene were carried out in the study. A fast-GC with 70 seconds chromatogram, with appropriate GC parameters is used for the study in order to cater for the handheld battery operated rapid detector. A spread of more than two times in sensitivity could be seen while using common GC carrier gases in the range of concentration (200-2000ppm) studied. By virtue of GC with SAW detector, excellent selectivity, repeatability, and long term stability is achieved. A detailed discussion on the reasons for the same is presented.

Remote in-line evaluation of acousto-elastic effects during elastic–plastic transition in an aluminum plate under uniaxial tensile and dynamic fatigue loading by laser generated, optically detected surface acoustic waves

Early detection and monitoring of heavy load induced plastic deformation in the structure is crucial for timely intervention before cracking occurs and the material completely fails. Ultrasound can be used for detecting plastic deformation provided the mechanical modulus, which can be probed via changes in velocities. This work presents a measurement scheme that makes use of optically detected, laser-induced surface acoustic waves (SAWs) for remote, real-time, online monitoring of the wave velocity during the elastic–plastic transition occurring in an aluminum plate undergoing a uniaxial tensile test and a dynamic fatigue test. Monochromatic SAWs were photoacoustically generated in a wavelength-controlled way through a transient thermal grating based laser ultrasonics excitation scheme. The SAWs were detected by a home-built photorefractive interferometer. The results reveal both regions of acceleration and slowing down, indicating that the material first stiffens and then starts to form microcracks that make it behave effectively softer for propagating SAWs.

Water Surface Acoustic Wave Detection by a Millimeter Wave Radar

Water Surface Acoustic Wave Detection by a Millimeter Wave Radar

Compact Probe for Non-Contact Ultrasonic Inspection with the Gas-Coupled Laser Acoustic Detection (GCLAD) Technique

BackgroundGas-Coupled Laser Acoustic Detection (GCLAD) is a non-contact ultrasonic detection technique whose functioning relies on the deviation that a probe laser beam sustains when intersected by an acoustic wavefront propagating in a fluid. The maximum sensitivity of the technique is typically obtained when the ultrasound insists on an ample portion of the probe laser beam extension, but such a condition can be unfeasible in several non-destructive testing applications (as in case of limited accessibility to the component).ObjectiveIn the present work, a solution is provided enabling transformation of the GCLAD device in a point detector. This is based on the use of two mirrors for confining the laser beam in an area with limited width and depth, where reflections however maximize the portion of the probe laser beam subjected to ultrasonic oscillation.MethodsThe characteristics of the obtained GCLAD probe are thoroughly analysed by applying the device to the detection of surface acoustic waves, propagating on a metal bar and refracting into the air. Two different inspection configurations are considered, whose difference lies in the mutual orientation between laser beam and solid surface. The effect on the received signal amplitude of the number of beam reflections, the dimensions of the resulting device, and the bar axisimmetry is investigated in both configurations. ResultsThe optimization of all the analysed standpoints enables obtaining a compact GCLAD probe that features the same signal amplitude of the non-compact alternative. To obtain maximum responsivity of the system, the number of reflections must be maximized, while the distance between the mirrors must be carefully set based on the employed inspection configuration and the eventual axisimmetry of the specimen. The devised GCLAD compact probe is capable of expanding the application range of the technique also to those cases in which the use of point detectors is desirable, without compromising the signal-to-noise ratio of the resulting acquisitions compared to the non-compact alternative.

Generation and detection of 50 GHz surface acoustic waves by extreme ultraviolet pulses

We use femtosecond extreme ultraviolet pulses derived from a free electron laser to excite and probe surface acoustic waves (SAWs) on the (001) surface of single crystal SrTiO3. SAWs are generated by a pair of 39.9 nm pulses crossed at the sample with the crossing angle defining the SAW wavelength at 84 nm. Detection of SAWs is performed via diffraction of a time-delayed 13.3 nm probe pulse by SAW-induced surface ripples. Despite the low reflectivity of the sample in the extreme ultraviolet range, the reflection mode detection is found to be efficient because of an increase in the diffraction efficiency for shorter wavelengths. We describe a methodology for extracting the SAW attenuation in the presence of a thermal grating, which is based on measuring the decay of oscillations at twice the SAW frequency. The proposed approach can be used to study ultrahigh frequency SAWs in a broad range of materials and will bridge the wave vector gap in surface phonon spectroscopy between Brillouin scattering and He atom scattering.

Acousto-Optic Comb Interrogation System for Random Fiber Grating Sensors with Sub-nm Resolution.

The broad-frequency response and nanometer-range displacements of ultrasound detection are essential for the characterization of small cracks, structural health monitoring and non-destructive evaluation. Those perturbations are generated at sub-nano-strain to nano-strain levels. This corresponds to the sub-nm level and, therefore, to about 0.1% of wavelength change at 1550 nm, making it difficult to detect them by conventional interferometric techniques. In this paper, we propose a demodulation system to read the random fiber grating spectrum using a self-heterodyne acousto-optic frequency comb. The system uses a self-heterodyne approach to extract phase and amplitude modulated signals to detect surface acoustic waves with sub-nanometer amplitudes in the frequency domain. The method can detect acoustic frequencies of 1 MHz and the associated displacement. The system is calibrated via phase detection with a heterodyne interferometer, which has a limited frequency response of up to 200 kHz. The goal is to achieve sub-nanometer strain detection at MHz frequency with random fiber gratings.

Study of water surface acoustic wave detection based on terahertz radar

Study of water surface acoustic wave detection based on terahertz radar

Detection of x rays by a surface acoustic delay line in contact with a diamond crystal

In this study, we present proof of concept for an x-ray detector. The hybrid device consists of a synthetic single crystal diamond in mechanical contact with a piezoelectric lithium niobate surface acoustic wave (SAW) delay line. Upon x-ray irradiation, the diamond crystal experiences a change in conductivity, which, in turn, very sensitively influences the SAW transmission on the delay line. This change in SAW attenuation is directly used to monitor the x-ray beam intensity. The SAW attenuation shows a monotonic variation with dose rate D in the studied range between 100 and 1800 μGy/s. While the response time leaves room for further improvement, the SAW detection principle offers the unique possibility for wireless remote powering and sensing.

Analysis of amplitude and frequency detection error of surface acoustic wave generated by laser line source

Laser-generated surface acoustic wave (SAW) is widely used in damage detection, elastic constant evaluation, film thickness determination and so on. Among them, the amplitude attenuation and frequency components of SAW are important index parameters in data analysis. In this paper, the diffuse attenuations of SAW generated by laser line source in non-contact and contact detection methods are analyzed respectively, and the calculation formulas are given. Contact SAW detector is widely used because of its high sensitivity and high stability, but it will produce frequency error. In this paper, the relationship between the detection line length of the contact detector and the signal amplitude, signal noise ratio (SNR) and frequency error is analyzed. It is found that for a certain detection line length, the higher the SAW center frequency, the greater the frequency error.

Non-destructive detection of machining-induced white layers through grain size and crystallographic texture-sensitive methods

Detection of machining-induced white layers is currently a destructive inspection process with a form of cross-sectional microscopy required. This paper, therefore, reports on the development of a novel non-destructive inspection method for detecting white layers using grain size-sensitive and crystallographic texture-sensitive techniques. It is shown that x-ray diffraction can be used to detect white layers as thin as 5 μm in Ti-6Al-4 V through measurement of diffraction peak breadths and diffraction peak intensities, due to the influence of the sub 100 nm grain size and high lattice strain in the white layer, as well as the strong crystallographic texture in this titanium alloy. Compared to the existing optical microscopy inspection method, which can take days due to the number of steps involved, the x-ray diffraction peak breadth method offers non-destructive white layer detection in a matter of minutes at a resolution of 5 μm or less that competes directly with the optical method. Spatially resolved acoustic spectroscopy, a laser-generated ultrasonic surface acoustic wave detection method, can also be used to identify anomalous surfaces, containing a white layer or swept grain material, due to its sensitivity to the crystallographic texture changes that arise in severely plastically deformed Ti-6Al-4V as in Titanium with 6 % Aluminium and 4% Vanadium.

GC-SAW and GC-FID performance comparison for fast analysis of volatile organic compounds

Objectives: To develop gas chromatograph (GC) based chemical agent detector and to compare the response of Surface Acoustic Wave (SAW) detector with Flame Ionization Detector (FID) for the development of a reliable and fast gas/vapour analyzer. Also, to describe the limitations of the FID over SAW detector. Methods: An uncoated 433.92 MHz SAW device was used as Gas Chromatography (GC) detector and its response was recorded and compared with conventional FID detector using short capillary column. The response of both the detectors were analyzed by using standard mixture of seven Volatile Organic Compounds (VOCs). Besides this comparison various key parameter of GC i.e. Flow, temperature and length of GC column were also optimized for fast GC analysis. Findings: After analyzing the fast GC data of both the detectors with same sample, it was observed that the resolution of chromatograms with SAW detector showed more resolved peaks as compare to the FID detector for the same GC parameters. Improvements/Applications: It is concluded that the SAW detector is more suitable for fast and reliable analysis of chemical vapors in rapid analysis. Keywords: Gas chromatograph detector; surface acoustic wave; volatile organic compounds

Surface acoustic wave detection of robust zero-resistance states under microwaves

Microwave-induced resistance oscillations (MIROs) and zero-resistance states (ZRSs) occur in high-mobility two-dimensional electron gas exposed to microwave (MW). We observe that the velocity shift ($\mathrm{\ensuremath{\Delta}}v/v$) oscillates in anticorrelation with MIRO, and $\mathrm{\ensuremath{\Delta}}v/v$ shows peaks at the minimal resistance of MIRO or at ZRS. The SAW velocity features of ZRS remain robust even in the absence of external driving current, which suggests the involvement of intrinsic mechanism in the nonequilibrium phase. In addition, under high-power MW, the phase (${\ensuremath{\varphi}}_{\mathrm{ac}}$) of ZRS stays constant at about 1/4, whereas the phase of the transitions in MIRO is reduced to below 0.10. We argue that the peaks of SAW velocity at ZRS may result from the inhomogeneity of superposed current domain structures. Moreover, a multiphoton process around $\ensuremath{\varepsilon}=1/2$ is observed in the SAW measurements.

Selective Surface Acoustic Wave Detection of the Temperature of a Liquid Microsample

Abstract—Surface acoustic wave-based high-sensitivity selective temperature sensor prototypes have been developed that operate independently of the rest of the physical parameters of liquids. The selectivity is provided by excluding physical contact between a surface acoustic wave and a tested sample. To enhance the sensitivity, the wave path from a transmitter to a receiver has been increased and the fifth wave harmonic has been used. The operation threshold of the prototypes has been reduced to 0.03–0.005°С.

Acoustic Far-Field Hypersonic Surface Wave Detection with Single Plasmonic Nanoantennas.

The optical properties of small metallic particles allow us to bridge the gap between the myriad of subdiffraction local phenomena and macroscopic optical elements. The optomechanical coupling between mechanical vibrations of Au nanoparticles and their optical response due to collective electronic oscillations leads to the emission and the detection of surface acoustic waves (SAWs) by single metallic nanoantennas. We take two Au nanoparticles, one acting as a source and the other as a receptor of SAWs and, even though these antennas are separated by distances orders of magnitude larger than the characteristic subnanometric displacements of vibrations, we probe the frequency content, wave speed, and amplitude decay of SAWs originating from the damping of coherent mechanical modes of the source. Two-color pump-probe experiments and numerical methods reveal the characteristic Rayleigh wave behavior of emitted SAWs, and show that the SAW-induced optical modulation of the receptor antenna allows us to accurately probe the frequency of the source, even when the eigenmodes of source and receptor are detuned.

Sub-limit detection in SAW sensors by FFT spectral analysis of frequency time instability

PurposeThe detection of H2 concentrations in concentrations undetectable by the conventional detection method of surface acoustic wave (SAW) sensors based on frequency shift, by correlating analyte presence with Fourier spectra components.Design/methodology/approachFast Fourier Transform (FFT) and autocorrelation analysis of phase noise in a SnO2-coated SAW sensor was performed. Fourier spectra were obtained by FFT from the SAW sensor resonance frequency instability, in the absence of analyte, and for H2 concentrations between 0.08 and 0.4 per cent.FindingsAll analyte concentrations are below the sensor limit of detection, which is 0.8 per cent for H2. Although these analyte concentrations caused no significant change in the resonance frequency of the SAW resonator, the FFT spectra presented several modifications, namely, the appearance of a new peak and the decrease of randomness. The authors consider that the effect is because of the chaotic behavior of the temporal dependence of the SAW resonance frequency. This explanation is substantiated by the decrease observed in the SAW oscillator autocorrelation function, which is an indication for a chaotic behavior.Practical implicationsAs chaotic systems are extremely sensitive to perturbation, measurement methods based on chaos diagnosis could potentially greatly improve the SAW detection.Originality/valueFourier spectra components were correlated with analyte presence in concentrations undetectable by the conventional SAW detection method based on frequency shift.