Science.gov

Sample records for acoustic surface impedance

  1. Acoustic Impedance Measurement for Underground Surfaces.

    NASA Astrophysics Data System (ADS)

    Cockcroft, Paul William

    Available from UMI in association with The British Library. Requires signed TDF. This thesis investigates the measurement of acoustic impedance for surfaces likely to be found in underground coal mines. By introducing the concepts of industrial noise, the effects of noise on the ear and relevant legislation the need for the protection of workers can be appreciated. Representative acoustic impedance values are vital as input for existing computer models that predict sound levels in various underground environments. These enable the mining engineer to predict the noise level at any point within a mine in the vicinity of noisy machinery. The concepts of acoustic intensity and acoustic impedance are investigated and different acoustic impedance measurement techniques are detailed. The possible use of either an impedance tube or an intensity meter for these kinds of measurements are suggested. The problems with acoustic intensity and acoustic impedance measurements are discussed with reference to the restraints that an underground environment imposes on any measurement technique. The impedance tube method for work in an acoustics laboratory is shown and the theory explained, accompanied by a few representative results. The use of a Metravib intensity meter in a soundproof chamber to gain impedance values is explained in detail. The accompanying software for the analysis of the two measured pressure signals is shown as well as the actual results for a variety of test surfaces. The use of a Nagra IV-SJ tape recorder is investigated to determine the effect of recording on the measurement and subsequent analysis of the input signals, particularly with reference to the phase difference introduced between the two simultaneous pressure signals. The subsequent use of a Norwegian Electronic intensity meter, including a proposal for underground work, is shown along with results for tests completed with this piece of equipment. Finally, recommendations are made on how to link up

  2. Estimating surface acoustic impedance with the inverse method.

    PubMed

    Piechowicz, Janusz

    2011-01-01

    Sound field parameters are predicted with numerical methods in sound control systems, in acoustic designs of building and in sound field simulations. Those methods define the acoustic properties of surfaces, such as sound absorption coefficients or acoustic impedance, to determine boundary conditions. Several in situ measurement techniques were developed; one of them uses 2 microphones to measure direct and reflected sound over a planar test surface. Another approach is used in the inverse boundary elements method, in which estimating acoustic impedance of a surface is expressed as an inverse boundary problem. The boundary values can be found from multipoint sound pressure measurements in the interior of a room. This method can be applied to arbitrarily-shaped surfaces. This investigation is part of a research programme on using inverse methods in industrial room acoustics.

  3. High transmission acoustic focusing by impedance-matched acoustic meta-surfaces

    NASA Astrophysics Data System (ADS)

    Al Jahdali, Rasha; Wu, Ying

    2016-01-01

    Impedance is an important issue in the design of acoustic lenses because mismatched impedance is detrimental to real focusing applications. Here, we report two designs of acoustic lenses that focus acoustic waves in water and air, respectively. They are tailored by acoustic meta-surfaces, which are rigid thin plates decorated with periodically distributed sub-wavelength slits. Their respective building blocks are constructed from the coiling-up spaces in water and the layered structures in air. Analytic analysis based on coupled-mode theory and transfer matrix reveals that the impedances of the lenses are matched to those of the background media. With these impedance-matched acoustic lenses, we demonstrate the acoustic focusing effect by finite-element simulations.

  4. A new method to measure the acoustic surface impedance outdoors.

    PubMed

    Carpinello, S; L'Hermite, Ph; Bérengier, M; Licitra, G

    2004-01-01

    In the European countries noise pollution is considered to be one of the most important environmental problems. With respect to traffic noise, different researchers are working on the reduction of noise at the source, on the modelling of the acoustic absorption of the road structure and on the effects of the pavement on the propagation. The aim of this paper is to propose a new method to measure the acoustic impedance of surfaces located outdoors, which allows us to further noise propagation models, in order to evaluate exactly the noise exposure.

  5. Air-ground interface: Surface waves, surface impedance and acoustic-to-seismic coupling coefficient

    NASA Technical Reports Server (NTRS)

    Daigle, Gilles; Embleton, Tony

    1990-01-01

    In atmospheric acoustics, the subject of surface waves has been an area of discussion for many years. The existence of an acoustic surface wave is now well established theoretically. The mathematical solution for spherical wave propagation above an impedance boundary includes the possibility of a contribution that possesses all the standard properties for a surface wave. Surface waves exist when the surface is sufficiently porous, relative to its acoustical resistance, that it can influence the airborne particle velocity near the surface and reduce the phase velocity of sound waves in air at the surface. This traps some of the sound energy in the air to remain near the surface as it propagates. Above porous grounds, the existence of surface waves has eluded direct experimental confirmation (pulse experiments have failed to show a separate arrival expected from the reduced phase speed) and indirect evidence for its existence has appeared contradictory. The experimental evidence for the existence of an acoustical surface wave above porous boundaries is reviewed. Recent measurements including pulse experiments are also described. A few years ago the acoustic impedance of a grass-covered surface was measured in the frequency range 30 to 300 Hz. Here, further measurements on the same site are discussed. These measurements include core samples, a shallow refractive survey to determine the seismic velocities, and measurements of the acoustic-to-seismic coupling coefficient.

  6. Directional Reflective Surface Formed via Gradient-Impeding Acoustic Meta-Surfaces

    PubMed Central

    Song, Kyungjun; Kim, Jedo; Hur, Shin; Kwak, Jun-Hyuk; Lee, Seong-Hyun; Kim, Taesung

    2016-01-01

    Artificially designed acoustic meta-surfaces have the ability to manipulate sound energy to an extraordinary extent. Here, we report on a new type of directional reflective surface consisting of an array of sub-wavelength Helmholtz resonators with varying internal coiled path lengths, which induce a reflection phase gradient along a planar acoustic meta-surface. The acoustically reshaped reflective surface created by the gradient-impeding meta-surface yields a distinct focal line similar to a parabolic cylinder antenna, and is used for directive sound beamforming. Focused beam steering can be also obtained by repositioning the source (or receiver) off axis, i.e., displaced from the focal line. Besides flat reflective surfaces, complex surfaces such as convex or conformal shapes may be used for sound beamforming, thus facilitating easy application in sound reinforcement systems. Therefore, directional reflective surfaces have promising applications in fields such as acoustic imaging, sonic weaponry, and underwater communication. PMID:27562634

  7. Directional Reflective Surface Formed via Gradient-Impeding Acoustic Meta-Surfaces

    NASA Astrophysics Data System (ADS)

    Song, Kyungjun; Kim, Jedo; Hur, Shin; Kwak, Jun-Hyuk; Lee, Seong-Hyun; Kim, Taesung

    2016-08-01

    Artificially designed acoustic meta-surfaces have the ability to manipulate sound energy to an extraordinary extent. Here, we report on a new type of directional reflective surface consisting of an array of sub-wavelength Helmholtz resonators with varying internal coiled path lengths, which induce a reflection phase gradient along a planar acoustic meta-surface. The acoustically reshaped reflective surface created by the gradient-impeding meta-surface yields a distinct focal line similar to a parabolic cylinder antenna, and is used for directive sound beamforming. Focused beam steering can be also obtained by repositioning the source (or receiver) off axis, i.e., displaced from the focal line. Besides flat reflective surfaces, complex surfaces such as convex or conformal shapes may be used for sound beamforming, thus facilitating easy application in sound reinforcement systems. Therefore, directional reflective surfaces have promising applications in fields such as acoustic imaging, sonic weaponry, and underwater communication.

  8. Acoustic Ground-Impedance Meter

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.

    1983-01-01

    Helmoltz resonator used in compact, portable meter measures acoustic impedance of ground or other surfaces. Earth's surface is subject of increasing acoustical investigations because of its importance in aircraft noise prediction and measurment. Meter offers several advantages. Is compact and portable and set up at any test site, irrespective of landscape features, weather or other environmental condition.

  9. Measurement of cantilever vibration using impedance-loaded surface acoustic wave sensor

    NASA Astrophysics Data System (ADS)

    Oishi, Masaki; Hamashima, Hiromitsu; Kondoh, Jun

    2016-07-01

    In this study, an impedance-loaded surface acoustic wave (SAW) sensor was demonstrated to monitor the vibration frequency. Commercialized pressure sensors and a variable capacitor were chosen as external sensors, which were connected to a reflector on a SAW device. As the reflection coefficient of the reflector depended on the impedance, the echo amplitude was influenced by changes in the impedance of the external sensor. The vibration frequency of the cantilever was determined by monitoring the echo amplitude of the SAW device. Moreover, the attenuation constant of an envelope was estimated. The results of our feasibility study indicate that the impedance-loaded SAW sensor can be applied as a detector for structural health monitoring.

  10. Measured and calculated acoustic attenuation rates of tuned resonator arrays for two surface impedance distribution models with flow

    NASA Technical Reports Server (NTRS)

    Parrott, Tony L.; Abrahamson, A. Louis; Jones, Michael G.

    1988-01-01

    An experiment was performed to validate two analytical models for predicting low frequency attenuation of duct liner configurations built from an array of seven resonators that could be individually tuned via adjustable cavity depths. These analytical models had previously been developed for high frequency aero-engine inlet duct liner design. In the low frequency application, the liner surface impedance distribution is unavoidably spatially varying by virtue of available fabrication techniques. The characteristic length of this spatial variation may be a significant fraction of the acoustic wavelength. Comparison of measured and predicted attenuation rates and transmission losses for both modal decomposition and finite element propagation models were in good to excellent agreement for a test frequency range that included the first and second cavity resonance frequencies. This was true for either of two surface impedance distribution modeling procedures used to simplify the impedance boundary conditions. In the presence of mean flow, measurements revealed a fine scale structure of acoustic hot spots in the attenuation and phase profiles. These details were accurately predicted by the finite element model. Since no impedance changes due to mean flow were assumed, it is concluded that this fine scale structure was due to convective effects of the mean flow interacting with the surface impedance nonuniformities.

  11. Anisotropic Artificial Impedance Surfaces

    NASA Astrophysics Data System (ADS)

    Quarfoth, Ryan Gordon

    Anisotropic artificial impedance surfaces are a group of planar materials that can be modeled by the tensor impedance boundary condition. This boundary condition relates the electric and magnetic field components on a surface using a 2x2 tensor. The advantage of using the tensor impedance boundary condition, and by extension anisotropic artificial impedance surfaces, is that the method allows large and complex structures to be modeled quickly and accurately using a planar boundary condition. This thesis presents the theory of anisotropic impedance surfaces and multiple applications. Anisotropic impedance surfaces are a generalization of scalar impedance surfaces. Unlike the scalar version, anisotropic impedance surfaces have material properties that are dependent on the polarization and wave vector of electromagnetic radiation that interacts with the surface. This allows anisotropic impedance surfaces to be used for applications that scalar surfaces cannot achieve. Three of these applications are presented in this thesis. The first is an anisotropic surface wave waveguide which allows propagation in one direction, but passes radiation in the orthogonal direction without reflection. The second application is a surface wave beam shifter which splits a surface wave beam in two directions and reduces the scattering from an object placed on the surface. The third application is a patterned surface which can alter the scattered radiation pattern of a rectangular shape. For each application, anisotropic impedance surfaces are constructed using periodic unit cells. These unit cells are designed to give the desired surface impedance characteristics by modifying a patterned metallic patch on a grounded dielectric substrate. Multiple unit cell geometries are analyzed in order to find the setup with the best performance in terms of impedance characteristics and frequency bandwidth.

  12. Manipulating acoustic wavefront by inhomogeneous impedance and steerable extraordinary reflection.

    PubMed

    Zhao, Jiajun; Li, Baowen; Chen, Zhining; Qiu, Cheng-Wei

    2013-01-01

    We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community. Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL). IGSL is based on Green's function and integral equation, instead of Fermat's principle for optical wavefront manipulation. Remarkably, via the adjustment of the designed specific acoustic impedance, extraordinary reflection can be steered for unprecedented acoustic wavefront while that ordinary reflection can be surprisingly switched on or off. The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators.

  13. Manipulating Acoustic Wavefront by Inhomogeneous Impedance and Steerable Extraordinary Reflection

    PubMed Central

    Zhao, Jiajun; Li, Baowen; Chen, Zhining; Qiu, Cheng-Wei

    2013-01-01

    We unveil the connection between the acoustic impedance along a flat surface and the reflected acoustic wavefront, in order to empower a wide wariety of novel applications in acoustic community. Our designed flat surface can generate double reflections: the ordinary reflection and the extraordinary one whose wavefront is manipulated by the proposed impedance-governed generalized Snell's law of reflection (IGSL). IGSL is based on Green's function and integral equation, instead of Fermat's principle for optical wavefront manipulation. Remarkably, via the adjustment of the designed specific acoustic impedance, extraordinary reflection can be steered for unprecedented acoustic wavefront while that ordinary reflection can be surprisingly switched on or off. The realization of the complex discontinuity of the impedance surface has been proposed using Helmholtz resonators. PMID:23985717

  14. Manipulate acoustic waves by impedance matched acoustic metasurfaces

    NASA Astrophysics Data System (ADS)

    Wu, Ying; Mei, Jun; Aljahdali, Rasha

    We design a type of acoustic metasurface, which is composed of carefully designed slits in a rigid thin plate. The effective refractive indices of different slits are different but the impedances are kept the same as that of the host medium. Numerical simulations show that such a metasurface can redirect or reflect a normally incident wave at different frequencies, even though it is impedance matched to the host medium. We show that the underlying mechanisms can be understood by using the generalized Snell's law, and a unified analytic model based on mode-coupling theory. We demonstrate some simple realization of such acoustic metasurface with real materials. The principle is also extended to the design of planar acoustic lens which can focus acoustic waves. Manipulate acoustic waves by impedance matched acoustic metasurfaces.

  15. Effects of Liner Geometry on Acoustic Impedance

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Tracy, Maureen B.; Watson, Willie R.; Parrott, Tony L.

    2002-01-01

    Current aircraft engine nacelles typically contain acoustic liners consisting of perforated sheets bonded onto honeycomb cavities. Numerous models have been developed to predict the acoustic impedance of these liners in the presence of grazing flow, and to use that information with aeroacoustic propagation codes to assess nacelle liner noise suppression. Recent efforts have provided advances in impedance education methodologies that offer more accurate determinations of acoustic liner properties in the presence of grazing flow. The current report provides the results of a parametric study, in which a finite element method was used to assess the effects of variations of the following geometric parameters on liner impedance, with and without the presence of grazing flow: percent open area, sheet thickness, sheet thickness-to-hole diameter ratio and cavity depth. Normal incidence acoustic impedances were determined for eight acoustic liners, consisting of punched aluminum facesheets bonded to hexcell honeycomb cavities. Similar liners were tested in the NASA Langley Research Center grazing incidence tube to determine their response in the presence of grazing flow. The resultant data provide a quantitative assessment of the effects of these perforate, single-layer liner parameters on the acoustic impedance of the liner.

  16. Method of Adjusting Acoustic Impedances for Impedance-Tunable Acoustic Segments

    NASA Technical Reports Server (NTRS)

    Jones, Kennie H (Inventor); Nark, Douglas M. (Inventor); Jones, Michael G. (Inventor); Parrott, Tony L. (Inventor); Lodding, Kenneth N. (Inventor)

    2012-01-01

    A method is provided for making localized decisions and taking localized actions to achieve a global solution. In an embodiment of the present invention, acoustic impedances for impedance-tunable acoustic segments are adjusted. A first acoustic segment through an N-th acoustic segment are defined. To start the process, the first acoustic segment is designated as a leader and a noise-reducing impedance is determined therefor. This is accomplished using (i) one or more metrics associated with the acoustic wave at the leader, and (ii) the metric(s) associated with the acoustic wave at the N-th acoustic segment. The leader, the N-th acoustic segment, and each of the acoustic segments exclusive of the leader and the N-th acoustic segment, are tuned to the noise-reducing impedance. The current leader is then excluded from subsequent processing steps. The designation of leader is then given one of the remaining acoustic segments, and the process is repeated for each of the acoustic segments through an (N-1)-th one of the acoustic segments.

  17. Acoustic impedance measurements of pulse tube refrigerators

    NASA Astrophysics Data System (ADS)

    Iwase, Takashi; Biwa, Tetsushi; Yazaki, Taichi

    2010-02-01

    Complex acoustic impedance is determined in a prototype refrigerator that can mimic orifice-type, inertance-type, and double inlet-type pulse tube refrigerators from simultaneous measurements of pressure and velocity oscillations at the cold end. The impedance measurements revealed the means by which the oscillatory flow condition in the basic pulse tube refrigerator is improved by additional components such as a valve and a tank. The working mechanism of pulse tube refrigerators is explained based on an electrical circuit analogy.

  18. Acoustic impedance testing for aeroacoustic applications

    NASA Astrophysics Data System (ADS)

    Schultz, Todd

    Accurate acoustic propagation models are required to characterize and subsequently reduce aircraft engine noise. These models ultimately rely on acoustic impedance measurements of candidate materials used in sound-absorbing liners. The standard two-microphone method (TMM) is widely used to estimate acoustic impedance but is limited in frequency range and does not provide uncertainty estimates, which are essential for data quality assessment and model validation. This dissertation presents a systematic framework to estimate uncertainty and extend the frequency range of acoustic impedance testing. Uncertainty estimation for acoustic impedance data using the TMM is made via two methods. The first employs a standard analytical technique based on linear perturbations and provides useful scaling information. The second uses a Monte Carlo technique that permits the propagation of arbitrarily large uncertainties. Both methods are applied to the TMM for simulated data representative of sound-hard and sound-soft acoustic materials. The results indicate that the analytical technique can lead to false conclusions about the magnitude and importance of specific error sources. Furthermore, the uncertainty in acoustic impedance is strongly dependent on the frequency and the uncertainty in the microphone locations. Next, an increased frequency range of acoustic impedance testing is investigated via two methods. The first method reduces the size of the test specimen (from 25.4 mm square to 8.5 mm square) and uses the standard TMM. This method has issues concerning specimen nonuniformity because the small specimens may not be representative of the material. The second method increases the duct cross section and, hence, the required complexity of the sound field propagation model. A comparison among all three methods is conducted for each of the three specimens: two different ceramic tubular specimens and a single degree-of-freedom liner. The results show good agreement between the

  19. Differences in acoustic impedance of fresh and embedded human trabecular bone samples-Scanning acoustic microscopy and numerical evaluation.

    PubMed

    Ojanen, Xiaowei; Töyräs, Juha; Inkinen, Satu I; Malo, Markus K H; Isaksson, Hanna; Jurvelin, Jukka S

    2016-09-01

    Trabecular bone samples are traditionally embedded and polished for scanning acoustic microscopy (SAM). The effect of sample processing, including dehydration, on the acoustic impedance of bone is unknown. In this study, acoustic impedance of human trabecular bone samples (n = 8) was experimentally assessed before (fresh) and after embedding using SAM and two-dimensional (2-D) finite-difference time domain simulations. Fresh samples were polished with sandpapers of different grit (P1000, P2500, and P4000). Experimental results indicated that acoustic impedance of samples increased significantly after embedding [mean values 3.7 MRayl (fresh), 6.1 MRayl (embedded), p < 0.001]. After polishing with different papers, no significant changes in acoustic impedance were found, even though higher mean values were detected after polishing with finer (P2500 and P4000) papers. A linear correlation (r = 0.854, p < 0.05) was found between the acoustic impedance values of embedded and fresh bone samples polished using P2500 SiC paper. In numerical simulations dehydration increased the acoustic impedance of trabecular bone (38%), whereas changes in surface roughness of bone had a minor effect on the acoustic impedance (-1.56%/0.1 μm). Thereby, the numerical simulations corroborated the experimental findings. In conclusion, acoustic impedance measurement of fresh trabecular bone is possible and may provide realistic material values similar to those of living bone.

  20. Concentric artificial impedance surface for directional sound beamforming

    NASA Astrophysics Data System (ADS)

    Song, Kyungjun; Anzan-Uz-Zaman, Md.; Kwak, Jun-Hyuk; Jung, Joo-Yun; Kim, Jedo; Hur, Shin

    2017-03-01

    Utilizing acoustic metasurfaces consisting of subwavelength resonant textures, we design an artificial impedance surface by creating a new boundary condition. We demonstrate a circular artificial impedance surface with surface impedance modulation for directional sound beamforming in three-dimensional space. This artificial impedance surface is implemented by revolving two-dimensional Helmholtz resonators with varying internal coiled path. Physically, the textured surface has inductive surface impedance on its inner circular patterns and capacitive surface impedance on its outer circular patterns. Directional receive beamforming can be achieved using an omnidirectional microphone located at the focal point formed by the gradient-impeding surface. In addition, the uniaxial surface impedance patterning inside the circular aperture can be used for steering the direction of the main lobe of the radiation pattern.

  1. High-Frequency Acoustic Impedance Imaging of Cancer Cells.

    PubMed

    Fadhel, Muhannad N; Berndl, Elizabeth S L; Strohm, Eric M; Kolios, Michael C

    2015-10-01

    Variations in the acoustic impedance throughout cells and tissue can be used to gain insight into cellular microstructures and the physiologic state of the cell. Ultrasound imaging can be used to create a map of the acoustic impedance, on which fluctuations can be used to help identify the dominant ultrasound scattering source in cells, providing information for ultrasound tissue characterization. The physiologic state of a cell can be inferred from the average acoustic impedance values, as many cellular physiologic changes are linked to an alteration in their mechanical properties. A recently proposed method, acoustic impedance imaging, has been used to measure the acoustic impedance maps of biological tissues, but the method has not been used to characterize individual cells. Using this method to image cells can result in more precise acoustic impedance maps of cells than obtained previously using time-resolved acoustic microscopy. We employed an acoustic microscope using a transducer with a center frequency of 375 MHz to calculate the acoustic impedance of normal (MCF-10 A) and cancerous (MCF-7) breast cells. The generated acoustic impedance maps and simulations suggest that the position of the nucleus with respect to the polystyrene substrate may have an effect on the measured acoustic impedance value of the cell. Fluorescence microscopy and confocal microscopy were used to correlate acoustic impedance images with the position of the nucleus within the cell. The average acoustic impedance statistically differed between normal and cancerous breast cells (1.636 ± 0.010 MRayl vs. 1.612 ± 0.006 MRayl), indicating that acoustic impedance could be used to differentiate between normal and cancerous cells.

  2. Modifying the acoustic impedance of polyurea-based composites

    NASA Astrophysics Data System (ADS)

    Nantasetphong, Wiroj; Amirkhizi, Alireza V.; Jia, Zhanzhan; Nemat-Nasser, Sia

    2013-04-01

    Acoustic impedance is a material property that depends on mass density and acoustic wave speed. An impedance mismatch between two media leads to the partial reflection of an acoustic wave sent from one medium to another. Active sonar is one example of a useful application of this phenomenon, where reflected and scattered acoustic waves enable the detection of objects. If the impedance of an object is matched to that of the surrounding medium, however, the object may be hidden from observation (at least directly) by sonar. In this study, polyurea composites are developed to facilitate such impedance matching. Polyurea is used due to its excellent blast-mitigating properties, easy casting, corrosion protection, abrasion resistance, and various uses in current military technology. Since pure polyurea has impedance higher than that of water (the current medium of interest), low mass density phenolic microballoon particles are added to create composite materials with reduced effective impedances. The volume fraction of particles is varied to study the effect of filler quantity on the acoustic impedance of the resulting composite. The composites are experimentally characterized via ultrasonic measurements. Computational models based on the method of dilute-randomly-distributed inclusions are developed and compared with the experimental results. These experiments and models will facilitate the design of new elastomeric composites with desirable acoustic impedances.

  3. Deduction of the acoustic impedance of the ground via a simulated three-dimensional microphone array.

    PubMed

    Alberts, W C Kirkpatrick; Sanchez, Kevin J

    2013-11-01

    While commonly used ground impedance deduction methods often utilize pairs of vertically separated microphones, deployed arrays rarely have this configuration, which increases the difficulty in automatically deducing local ground impedance from these arrays. The ability to deduce ground impedance using random sounds incident on a three-dimensional array would increase, for example, the accuracy of estimated elevation angles. The methods described by the American National Standards Institute Method for Determining the Acoustic Impedance of Ground Surfaces are extended to simulate deducing ground impedance by a three-dimensional array. Ground parameters indicative of grassland are successfully determined using a simulated three-dimensional array.

  4. Absorption and impedance boundary conditions for phased geometrical-acoustics methods.

    PubMed

    Jeong, Cheol-Ho

    2012-10-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, both absorption coefficients and surface impedances of the boundary surfaces can be used, but no guideline has been developed on which boundary condition produces accurate results. In this study, various boundary conditions in terms of normal, random, and field incidence absorption coefficients and normal incidence surface impedance are used in a phased beam tracing model, and the simulated results are validated with boundary element solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. Effects of the neglect of reflection phase shift are also investigated. It is concluded that the impedance, random incidence, and field incidence absorption boundary conditions produce reasonable results with some exceptions at low frequencies for acoustically soft materials.

  5. Tests Of Shear-Flow Model For Acoustic Impedance

    NASA Technical Reports Server (NTRS)

    Parrot, Tony L.; Watson, Willie R.; Jones, Michael G.

    1992-01-01

    Tests described in report conducted to validate two-dimensional shear-flow analytical model for determination of acoustic impedance of acoustic liner in grazing-incidence, grazing-flow environment by use of infinite-waveguide method. Tests successful for both upstream and downstream propagations. Work has potential for utility in testing of engine ducts in commercial aircraft.

  6. Matching Impedances and Modes in Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.

    1985-01-01

    Temperature differences accommodated with tunable coupler. Report discusses schemes for coupling sound efficiently from cool outside atmosphere into hot acoustic-levitation chamber. Theoretical studies have practical implications for material-processing systems that employ acoustic levitation.

  7. Comparison of Two Acoustic Waveguide Methods for Determining Liner Impedance

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Watson, Willie R.; Tracy, Maureen B.; Parrott, Tony L.

    2001-01-01

    Acoustic measurements taken in a flow impedance tube are used to assess the relative accuracy of two waveguide methods for impedance eduction in the presence of grazing flow. The aeroacoustic environment is assumed to contain forward and backward-traveling acoustic waves, consisting of multiple modes, and uniform mean flow. Both methods require a measurement of the complex acoustic pressure profile over the length of the test liner. The Single Mode Method assumes that the sound pressure level and phase decay-rates of a single progressive mode can be extracted from this measured complex acoustic pressure profile. No a priori assumptions are made in the Finite Element. Method regarding the modal or reflection content in the measured acoustic pressure profile. The integrity of each method is initially demonstrated by how well their no-flow impedances match those acquired in a normal incidence impedance tube. These tests were conducted using ceramic tubular and conventional perforate liners. Ceramic tubular liners were included because of their impedance insensitivity to mean flow effects. Conversely, the conventional perforate liner was included because its impedance is known to be sensitive to mean flow velocity effects. Excellent comparisons between impedance values educed with the two waveguide methods in the absence of mean flow and the corresponding values educed with the normal incident impedance tube were observed. The two methods are then compared for mean flow Mach numbers up to 0.5, and are shown to give consistent results for both types of test liners. The quality of the results indicates that the Single Mode Method should be used when the measured acoustic pressure profile is clearly dominated by a single progressive mode, and the Finite Element Method should be used for all other cases.

  8. Optimization and Control of Acoustic Liner Impedance with Bias Flow

    NASA Technical Reports Server (NTRS)

    Wood, Houston; Follet, Jesse

    2000-01-01

    Because communities are impacted by steady increases in aircraft traffic, aircraft noise continues to be a growing problem for the growth of commercial aviation. Research has focused on improving the design of specific high noise source areas of aircraft and on noise control measures to alleviate noise radiated from aircraft to the surrounding environment. Engine duct liners have long been a principal means of attenuating engine noise. The ability to control in-situ the acoustic impedance of a liner would provide a valuable tool to improve the performance of liners. The acoustic impedance of a liner is directly related to the sound absorption qualities of that liner. Increased attenuation rates, the ability to change liner acoustic impedance to match various operating conditions, or the ability to tune a liner to more precisely match design impedance represent some ways that in-situ impedance control could be useful. With this in mind, the research to be investigated will focus on improvements in the ability to control liner impedance using a mean flow through the liner which is referred to as bias flow.

  9. Validation of an Acoustic Impedance Prediction Model for Skewed Resonators

    NASA Technical Reports Server (NTRS)

    Howerton, Brian M.; Parrott, Tony L.

    2009-01-01

    An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

  10. Effects of Flow Profile on Educed Acoustic Liner Impedance

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Watson, Willie r.; Nark, Douglas M.

    2010-01-01

    This paper presents results of an investigation of the effects of shear flow profile on impedance eduction processes employed at NASA Langley. Uniform and 1-D shear-flow propagation models are used to educe the acoustic impedance of three test liners based on aeroacoustic data acquired in the Langley Grazing Flow Impedance Tube, at source levels of 130, 140 and 150 dB, and at centerline Mach numbers of 0.0, 0.3 and 0.5. A ceramic tubular, calibration liner is used to evaluate the propagation models, as this liner is expected to be insensitive to SPL, grazing flow Mach number, and flow profile effects. The propagation models are then used to investigate the effects of shear flow profile on acoustic impedances educed for two conventional perforate-over-honeycomb liners. Results achieved with the uniform-flow models follow expected trends, but those educed with the 1-D shear-flow model do not, even for the calibration liner. However, when the flow profile used with the shear-flow model is varied to increase the Mach number gradient near the wall, results computed with the shear-flow model are well matched to those achieved with the uniform-flow model. This indicates the effects of flow profile on educed acoustic liner impedance are small, but more detailed investigations of the flow field throughout the duct are needed to better understand these effects.

  11. Impedance matched joined drill pipe for improved acoustic transmission

    DOEpatents

    Moss, William C.

    2000-01-01

    An impedance matched jointed drill pipe for improved acoustic transmission. A passive means and method that maximizes the amplitude and minimize the temporal dispersion of acoustic signals that are sent through a drill string, for use in a measurement while drilling telemetry system. The improvement in signal transmission is accomplished by replacing the standard joints in a drill string with joints constructed of a material that is impedance matched acoustically to the end of the drill pipe to which it is connected. Provides improvement in the measurement while drilling technique which can be utilized for well logging, directional drilling, and drilling dynamics, as well as gamma-ray spectroscopy while drilling post shot boreholes, such as utilized in drilling post shot boreholes.

  12. On the Propagation of Plane Acoustic Waves in a Duct With Flexible and Impedance Walls

    NASA Technical Reports Server (NTRS)

    Frendi, Abdelkader; Vu, Bruce

    2003-01-01

    This Technical Memorandum (TM) discusses the harmonic and random plane acoustic waves propagating from inside a duct to its surroundings. Various duct surfaces are considered, such as rigid, flexible, and impedance. In addition, the effects of a mean flow are studied when the duct alone is considered. Results show a significant reduction in overall sound pressure levels downstream of the impedance wall for both mean flow and no mean flow cases and for a narrow duct. When a wider duct is used, the overall sound pressure level (OSPL) reduction downstream of the impedance wall is much smaller. In the far field, the directivity is such that the overall sound pressure level is reduced by about 5 decibels (dB) on the side of the impedance wall. When a flexible surface is used, the far field directivity becomes asymmetric with an increase in the OSPL on the side of the flexible surface of about 7 dB.

  13. Acoustic Impedance Analysis with High-Frequency Ultrasound for Identification of Fatty Acid Species in the Liver.

    PubMed

    Ito, Kazuyo; Yoshida, Kenji; Maruyama, Hitoshi; Mamou, Jonathan; Yamaguchi, Tadashi

    2017-03-01

    Acoustic properties of free fatty acids present in the liver were studied as a possible basis for non-invasive ultrasonic diagnosis of non-alcoholic steatohepatitis. Acoustic impedance was measured for the following types of tissue samples: Four pathologic types of mouse liver, five kinds of FFAs in solvent and five kinds of FFAs in cultured Huh-7 cells. A transducer with an 80-MHz center frequency was incorporated into a scanning acoustic microscopy system. Acoustic impedance was calculated from the amplitude of the signal reflected from the specimen surface. The Kruskal-Wallis test revealed statistically significant differences (p < 0.01) in acoustic impedance not only among pathologic types, but also among the FFAs in solvent and in cultured Huh-7 cells. These results suggest that each of the FFAs, especially palmitate, oleate and palmitoleate acid, can be distinguished from each other, regardless of whether they were in solution or absorbed by cells.

  14. Fluid mechanical model of the acoustic impedance of small orifices

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Rogers, T.

    1976-01-01

    A fluid mechanical model of the acoustic behavior of small orifices is presented which predicts orifice resistance and reactance as a function of incident sound pressure level, frequency, and orifice geometry. Agreement between predicted and measured values is excellent. The model shows the following: (1) The acoustic flow in immediate neighborhood of the orifice can be modeled as a locally spherical flow. Within this near field, the flow is, to a first approximation, unsteady and incompressible. (2) At very low sound pressure levels, the orifice viscous resistance is directly related to the effect of boundary-layer displacement along the walls containing the orifice, and the orifice reactance is directly related to the inertia of the oscillating flow in the neighborhood of the orifice. (3) For large values of the incident acoustic pressure, the impedance is dominated by nonlinear jet-like effects. (4) For low values of the pressure, the resistance and reactance are roughly equal.

  15. Numerical analysis of acoustic impedance microscope utilizing acoustic lens transducer to examine cultured cells.

    PubMed

    Gunawan, Agus Indra; Hozumi, Naohiro; Takahashi, Kenta; Yoshida, Sachiko; Saijo, Yoshifumi; Kobayashi, Kazuto; Yamamoto, Seiji

    2015-12-01

    A new technique is proposed for non-contact quantitative cell observation using focused ultrasonic waves. This technique interprets acoustic reflection intensity into the characteristic acoustic impedance of the biological cell. The cells are cultured on a plastic film substrate. A focused acoustic beam is transmitted through the substrate to its interface with the cell. A two-dimensional (2-D) reflection intensity profile is obtained by scanning the focal point along the interface. A reference substance is observed under the same conditions. These two reflections are compared and interpreted into the characteristic acoustic impedance of the cell based on a calibration curve that was created prior to the observation. To create the calibration curve, a numerical analysis of the sound field is performed using Fourier Transforms and is verified using several saline solutions. Because the cells are suspended by two plastic films, no contamination is introduced during the observation. In a practical observation, a sapphire lens transducer with a center frequency of 300 MHz was employed using ZnO thin film. The objects studied were co-cultured rat-derived glial (astrocyte) cells and glioma cells. The result was the clear observation of the internal structure of the cells. The acoustic impedance of the cells was spreading between 1.62 and 1.72 MNs/m(3). Cytoskeleton was indicated by high acoustic impedance. The introduction of cytochalasin-B led to a significant reduction in the acoustic impedance of the glioma cells; its effect on the glial cells was less significant. It is believed that this non-contact observation method will be useful for continuous cell inspections.

  16. Antenna pattern control using impedance surfaces

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Liu, Kefeng; Tirkas, Panayiotis A.

    1993-01-01

    During the period of this research project, a comprehensive study of pyramidal horn antennas was conducted. Full-wave analytical and numerical techniques were developed to analyze horn antennas with or without impedance surfaces. Based on these full-wave analytic techniques, research was conducted on the use of impedance surfaces on the walls of the horn antennas to control the antenna radiation patterns without a substantial loss of antenna gain. It was found that the use of impedance surfaces could modify the antenna radiation patterns. In addition to the analytical and numerical models, experimental models were also constructed and they were used to validate the predictions. Excellent agreement between theoretical predictions and the measured data was obtained for pyramidal horns with perfectly conducting surfaces. Very good comparisons between numerical and experimental models were also obtained for horns with impedance surfaces.

  17. Surface impedance of transversely moving microwave ferrite

    NASA Astrophysics Data System (ADS)

    Mueller, R. S.

    1990-01-01

    A theoretical study was made of the surface impedance Z for an electromagnetic transverse magnetic wave from free space on a magnetized ferrite surface moving normal to the plane of incidence. It was found convenient to decompose the surface impedance into two transfer impedances, Z1 and Z2, which relate the hybrid reflected amplitudes to the amplitude of the incident wave. The surface impedance does not vary much with respect to the angle of incidence, so only the case of normal incidence (θi = 0°) was evaluated. Resonant poles at ƒc, [ƒc(ƒc + ƒm)]1/2, and ƒc + ƒm dominate the frequency characteristics of Z1 and Z2. The frequencies ƒc andƒm are the precessional frequency and magnetization frequency, respectively.

  18. A state feedback electro-acoustic transducer for active control of acoustic impedance.

    PubMed

    Samejima, Toshiya

    2003-03-01

    In this paper, a new control system in which the acoustic impedance of an electro-acoustic transducer diaphragm can be actively varied by modifying design parameters is presented and its effectiveness is theoretically investigated. The proposed control system is based on a state-space description of the control system derived from an electrical equivalent circuit of an electro-acoustic transducer to which a differentiating circuit is connected, and is designed using modem control theory. The optimal quadratic regulator is used in the control system design, with its quadratic performance index formulated for producing desired acoustic impedance. Computer simulations indicate that the acoustic impedance of the diaphragm can be significantly varied over a wide frequency range that includes the range below the resonance frequency of the electro-acoustic transducer. A computer model of the proposed control system is used to illustrate its application to semi-active noise control in a duct. It is demonstrated that the proposed control system provides substantial reductions in the noise radiating from the outlet of the duct, both in the stiffness control range and in the mass control range.

  19. Broadband liner impedance eduction for multimodal acoustic propagation in the presence of a mean flow

    NASA Astrophysics Data System (ADS)

    Troian, Renata; Dragna, Didier; Bailly, Christophe; Galland, Marie-Annick

    2017-03-01

    A new broadband impedance eduction method is introduced to identify the surface impedance of acoustic liners from in situ measurements on a test rig. Multimodal acoustic propagation is taken into account in order to reproduce realistic conditions. The present approach is based on the resolution of the linearized 3D Euler equations in the time domain. The broadband impedance time domain boundary condition is prescribed from a multipole impedance model, and is formulated as a differential form well-suited for high-order numerical methods. Numerical values of the model coefficients are determined by minimizing the difference between measured and simulated acoustic quantities, namely the insertion loss and wall pressure fluctuations at a few locations inside the duct. The minimization is performed through a multi-objective optimization thanks to the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The present eduction method is validated with benchmark data provided by NASA for plane wave propagation, and by synthesized numerical data for multimodal propagation.

  20. Acoustic impedance characterization via numerical resolution of the inverse Helmholtz problem

    NASA Astrophysics Data System (ADS)

    Scalo, Carlo; Patel, Danish; Gupta, Prateek

    2016-11-01

    Impedance boundary conditions (IBCs) regulate the relative phasing and amplitudes of pressure and velocity fluctuations and, therefore, the acoustic energy flux. We present a numerical method to determine the acoustic impedance at the surface of an arbitrarily shaped cavity as seen by a generically oriented incident external harmonic planar wave. The proposed method (conceptually) inverts the usual eigenvalue-solving procedure underlying Helmholtz solvers: the impedance at one or multiple (but not all) boundaries is an output of the calculation and is obtained via implicit reconstruction the linear acoustic waveform at the frequency of the incident wave. The linearized governing equations are discretized via a mixed finite-difference/finite-volume approach and are closed with a generalized equation of state. Results are validated against quasi one-dimensional cases derived via direct application of Rott's linear thermoacoustic theory and by comparison against fully compressible Navier-Stokes simulations. This work is motivated by the need to develop a comprehensive suite of predictive tools capable of performing high-fidelity simulations of compressible boundary layers over assigned IBCs, accurately representing the acoustic response of arbitrarily shaped porous cavities.

  1. Acoustic visualizations using surface mapping.

    PubMed

    Siltanen, Samuel; Robinson, Philip W; Saarelma, Jukka; Pätynen, Jukka; Tervo, Sakari; Savioja, Lauri; Lokki, Tapio

    2014-06-01

    Sound visualizations have been an integral part of room acoustics studies for more than a century. As acoustic measurement techniques and knowledge of hearing evolve, acousticians need more intuitive ways to represent increasingly complex data. Microphone array processing now allows accurate measurement of spatio-temporal acoustic properties. However, the multidimensional data can be a challenge to display coherently. This letter details a method of mapping visual representations of acoustic reflections from a receiver position to the surfaces from which the reflections originated. The resulting animations are presented as a spatial acoustic analysis tool.

  2. Sensing the characteristic acoustic impedance of a fluid utilizing acoustic pressure waves

    PubMed Central

    Antlinger, Hannes; Clara, Stefan; Beigelbeck, Roman; Cerimovic, Samir; Keplinger, Franz; Jakoby, Bernhard

    2012-01-01

    Ultrasonic sensors can be used to determine physical fluid parameters like viscosity, density, and speed of sound. In this contribution, we present the concept for an integrated sensor utilizing pressure waves to sense the characteristic acoustic impedance of a fluid. We note that the basic setup generally allows to determine the longitudinal viscosity and the speed of sound if it is operated in a resonant mode as will be discussed elsewhere. In this contribution, we particularly focus on a modified setup where interferences are suppressed by introducing a wedge reflector. This enables sensing of the liquid's characteristic acoustic impedance, which can serve as parameter in condition monitoring applications. We present a device model, experimental results and their evaluation. PMID:23565036

  3. Simulating Reflex Induced Changes in the Acoustic Impedance of the Ear.

    ERIC Educational Resources Information Center

    Sirlin, Mindy W.; Levitt, Harry

    1991-01-01

    A simple procedure for measuring changes in the acoustic impedance of the ear is described. The technique has several applications, including simulation using a standard coupler of changes in real ear impedance produced by the acoustic reflex, and calibration of response time of an otoadmittance meter. (Author/DB)

  4. Optimization of Acoustic Pressure Measurements for Impedance Eduction

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Watson, W. R.; Nark, D. M.

    2007-01-01

    As noise constraints become increasingly stringent, there is continued emphasis on the development of improved acoustic liner concepts to reduce the amount of fan noise radiated to communities surrounding airports. As a result, multiple analytical prediction tools and experimental rigs have been developed by industry and academia to support liner evaluation. NASA Langley has also placed considerable effort in this area over the last three decades. More recently, a finite element code (Q3D) based on a quasi-3D implementation of the convected Helmholtz equation has been combined with measured data acquired in the Langley Grazing Incidence Tube (GIT) to reduce liner impedance in the presence of grazing flow. A new Curved Duct Test Rig (CDTR) has also been developed to allow evaluation of liners in the presence of grazing flow and controlled, higher-order modes, with straight and curved waveguides. Upgraded versions of each of these two test rigs are expected to begin operation by early 2008. The Grazing Flow Impedance Tube (GFIT) will replace the GIT, and additional capabilities will be incorporated into the CDTR. The current investigation uses the Q3D finite element code to evaluate some of the key capabilities of these two test rigs. First, the Q3D code is used to evaluate the microphone distribution designed for the GFIT. Liners ranging in length from 51 to 610 mm are investigated to determine whether acceptable impedance eduction can be achieved with microphones placed on the wall opposite the liner. This analysis indicates the best results are achieved for liner lengths of at least 203 mm. Next, the effects of moving this GFIT microphone array to the wall adjacent to the liner are evaluated, and acceptable results are achieved if the microphones are placed off the centerline. Finally, the code is used to investigate potential microphone placements in the CDTR rigid wall adjacent to the wall containing an acoustic liner, to determine if sufficient fidelity can be

  5. Viscous effects on the acoustics and stability of a shear layer over an impedance wall

    NASA Astrophysics Data System (ADS)

    Khamis, Doran; Brambley, Edward James

    2017-01-01

    The effect of viscosity and thermal conduction on the acoustics in a shear layer above an impedance wall is investigated numerically and asymptotically by solving the compressible linearised Navier-Stokes equations. It is found that viscothermal effects can be as important as shear, and therefore including shear while neglecting viscothermal effects by solving the linearised Euler equations is questionable. In particular, the damping rate of upstream propagating waves is found to be dramatically under-predicted by the LEE in certain instances. The effects of viscosity on stability are also found to be important. Short wavelength disturbances are stabilised by viscosity, greatly altering the characteristic wavelength and maximum growth rate of instability. For the parameters typical of aeroacoustic simulations considered here, the Reynolds number below which the flow stabilizes ranges from $10^5$ to $10^7$. By assuming a thin but nonzero-thickness boundary layer, asymptotic analysis leads to a system of boundary layer governing equations for the acoustics. This system may be solved numerically to produce an effective impedance boundary condition, applicable at the wall of a uniform inviscid flow, that accounts for both the shear and viscosity within the boundary layer. An alternative asymptotic analysis in the high frequency limit yields a different set of equations with analytic solutions. The acoustic mode shapes and axial wavenumbers from both asymptotic analyses compare well with numerical solutions of the full LNSE. A closed-form effective impedance boundary condition is derived from the high-frequency asymptotics, suitable for application in frequency-domain numerical simulations. Finally, surface waves are considered, and it is shown that a viscous flow over an impedance lining supports a greater number of surface wave modes than an inviscid flow.

  6. Waveform-preserved unidirectional acoustic transmission based on impedance-matched acoustic metasurface and phononic crystal

    NASA Astrophysics Data System (ADS)

    Song, Ai-Ling; Chen, Tian-Ning; Wang, Xiao-Peng; Wan, Le-Le

    2016-08-01

    The waveform distortion happens in most of the unidirectional acoustic transmission (UAT) devices proposed before. In this paper, a novel type of waveform-preserved UAT device composed of an impedance-matched acoustic metasurface (AMS) and a phononic crystal (PC) structure is proposed and numerically investigated. The acoustic pressure field distributions and transmittance are calculated by using the finite element method. The subwavelength AMS that can modulate the wavefront of the transmitted wave at will is designed and the band structure of the PC structure is calculated and analyzed. The sound pressure field distributions demonstrate that the unidirectional acoustic transmission can be realized by the proposed UAT device without changing the waveforms of the output waves, which is the distinctive feature compared with the previous UAT devices. The physical mechanism of the unidirectional acoustic transmission is discussed by analyzing the refraction angle changes and partial band gap map. The calculated transmission spectra show that the UAT device is valid within a relatively broad frequency range. The simulation results agree well with the theoretical predictions. The proposed UAT device provides a good reference for designing waveform-preserved UAT devices and has potential applications in many fields, such as medical ultrasound, acoustic rectifiers, and noise insulation.

  7. Superconducting surface impedance under radiofrequency field

    DOE PAGES

    Xiao, Binping P.; Reece, Charles E.; Kelley, Michael J.

    2013-04-26

    Based on BCS theory with moving Cooper pairs, the electron states distribution at 0K and the probability of electron occupation with finite temperature have been derived and applied to anomalous skin effect theory to obtain the surface impedance of a superconductor under radiofrequency (RF) field. We present the numerical results for Nb and compare these with representative RF field-dependent effective surface resistance measurements from a 1.5 GHz resonant structure.

  8. Improved phonocardiogram system based on acoustic impedance matching.

    PubMed

    Schwartz, R S; Reeves, J T; Sodal, I E; Barnes, F S

    1980-04-01

    We considered that phonocardiographic recording could be improved 1) by minimizing the acoustic impedance mismatch between the precordial tissue and transducer, 2) by optimizing the configuration of the impedance-matching medium and transducer design, and 3) by storing signals in digital form through analog-to-digital conversion of analog recordings made at the bedside. The use of an aqueous coupling medium to improve energy transmission increased signal voltage approximately 100-fold over presently used commercial devices. Further match to the crystal was achieved by a concentrating horn configuration for the aqueous medium. Measured frequency response of the device in the range 1 Hz to 1 kHz was better than two other commercially tested microphones. Inspection of comparative phonocardiograms showed more information from the new device than from the two other commercial devices. Unfiltered digitized signals, using our microphone in normal subjects, demonstrated good beat-to-beat repeatability, but analog filtering to obtain the conventional phonocardiogram showed significant loss of information. The new instrument appears to be superior to those commercial devices tested in recording heart sounds.

  9. Bonding and impedance matching of acoustic transducers using silver epoxy.

    PubMed

    Son, Kyu Tak; Lee, Chin C

    2012-04-01

    Silver epoxy was selected to bond transducer plates on glass substrates. The properties and thickness of the bonding medium affect the electrical input impedance of the transducer. Thus, the thickness of the silver epoxy bonding layer was used as a design parameter to optimize the structure for the transducer input impedance to match the 50 Ω output impedance of most radio frequency (RF) generators. Simulation and experimental results show that nearly perfect matching is achieved without using any matching circuit. At the matching condition, the transducer operates at a frequency band a little bit below the half-wavelength resonant frequency of the piezoelectric plate. In experiments, lead titanate (PT) piezoelectric plates were employed. Both full-size, 11.5 mm × 2 mm × 0.4 mm, and half-size, 5.75 mm × 2 mm × 0.4 mm, can be well matched using optimal silver epoxy thickness. The transducer assemblies demonstrate high efficiency. The conversion loss from electrical power to acoustic power in soda-lime glass is 4.3 dB. This loss is low considering the fact that the transducers operate at off-resonance by 12%. With proper choice of silver epoxy thickness, the transducer can be matched at the fundamental, the 3rd and 5th harmonic frequencies. This leads to the possible realization of triple-band transducers. Reliability was assessed with thermal cycling test according to Telcordia GR-468-Core recommendation. Of the 30 transducer assemblies tested, none broke until 2900 cycles and 27 have sustained beyond 4050 cycles.

  10. Surface acoustic wave microfluidics.

    PubMed

    Ding, Xiaoyun; Li, Peng; Lin, Sz-Chin Steven; Stratton, Zackary S; Nama, Nitesh; Guo, Feng; Slotcavage, Daniel; Mao, Xiaole; Shi, Jinjie; Costanzo, Francesco; Huang, Tony Jun

    2013-09-21

    The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next.

  11. Surface acoustic wave microfluidics

    PubMed Central

    Ding, Xiaoyun; Li, Peng; Lin, Sz-Chin Steven; Stratton, Zackary S.; Nama, Nitesh; Guo, Feng; Slotcavage, Daniel; Mao, Xiaole; Shi, Jinjie; Costanzo, Francesco; Huang, Tony Jun

    2014-01-01

    The recent introduction of surface acoustic wave (SAW) technology onto lab-on-a-chip platforms has opened a new frontier in microfluidics. The advantages provided by such SAW microfluidics are numerous: simple fabrication, high biocompatibility, fast fluid actuation, versatility, compact and inexpensive devices and accessories, contact-free particle manipulation, and compatibility with other microfluidic components. We believe that these advantages enable SAW microfluidics to play a significant role in a variety of applications in biology, chemistry, engineering, and medicine. In this review article, we discuss the theory underpinning SAWs and their interactions with particles and the contacting fluids in which they are suspended. We then review the SAW-enabled microfluidic devices demonstrated to date, starting with devices that accomplish fluid mixing and transport through the use of travelling SAW; we follow that by reviewing the more recent innovations achieved with standing SAW that enable such actions as particle/cell focusing, sorting, and patterning. Finally, we look forward and appraise where the discipline of SAW microfluidics could go next. PMID:23900527

  12. Interior impedance wedge diffraction with surface waves

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Griesser, Timothy

    1988-01-01

    The exact impedance wedge solution is evaluated asymptotically using the method of steepest descents for plane wave illumination at normal incidence. Uniform but different impedances on each face are considered for both soft and hard polarizations. The asymptotic solution isolates the incident, singly reflected, multiply reflected, diffracted, and surface wave fields. Multiply reflected fields of any order are permitted. The multiply reflected fields from the exact solution are written as ratios of auxiliary Maliuzhinets functions, whereas a geometrical analysis gives the reflected fields as products of reflection coefficients. These two representations are shown to be identical in magnitude, phase and the angular range over which they exist. The diffracted field includes four Fresnel transition functions as in the perfect conductor case, and the expressions for the appropriate discontinuities at the shadow boundaries are presented. The surface wave exists over a finite angular range and only for certain surface impedances. A surface wave transition field is included to retain continuity. Computations are presented for interior wedge diffractions although the formulation is valid for both exterior and interior wedges.

  13. Gas hydrate saturation from acoustic impedance and resistivity logs in the shenhu area, south china sea

    USGS Publications Warehouse

    Wang, X.; Wu, S.; Lee, M.; Guo, Y.; Yang, S.; Liang, J.

    2011-01-01

    During the China's first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ???10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. ?? 2011 Elsevier Ltd.

  14. Inverse acoustic scattering problem in half-space with anisotropic random impedance

    NASA Astrophysics Data System (ADS)

    Helin, Tapio; Lassas, Matti; Päivärinta, Lassi

    2017-02-01

    We study an inverse acoustic scattering problem in half-space with a probabilistic impedance boundary value condition. The Robin coefficient (surface impedance) is assumed to be a Gaussian random function with a pseudodifferential operator describing the covariance. We measure the amplitude of the backscattered field averaged over the frequency band and assume that the data is generated by a single realization of λ. Our main result is to show that under certain conditions the principal symbol of the covariance operator of λ is uniquely determined. Most importantly, no approximations are needed and we can solve the full non-linear inverse problem. We concentrate on anisotropic models for the principal symbol, which leads to the analysis of a novel anisotropic spherical Radon transform and its invertibility.

  15. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  16. Antenna pattern control using impedance surfaces

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Liu, Kefeng

    1992-01-01

    During this research period, we have effectively transferred existing computer codes from CRAY supercomputer to work station based systems. The work station based version of our code preserved the accuracy of the numerical computations while giving a much better turn-around time than the CRAY supercomputer. Such a task relieved us of the heavy dependence of the supercomputer account budget and made codes developed in this research project more feasible for applications. The analysis of pyramidal horns with impedance surfaces was our major focus during this research period. Three different modeling algorithms in analyzing lossy impedance surfaces were investigated and compared with measured data. Through this investigation, we discovered that a hybrid Fourier transform technique, which uses the eigen mode in the stepped waveguide section and the Fourier transformed field distributions across the stepped discontinuities for lossy impedances coating, gives a better accuracy in analyzing lossy coatings. After a further refinement of the present technique, we will perform an accurate radiation pattern synthesis in the coming reporting period.

  17. Anisotropic impedance surfaces for enhanced antenna isolation

    NASA Astrophysics Data System (ADS)

    Miragliotta, Joseph A.; Shrekenhamer, David; Sievenpiper, Daniel F.

    2015-09-01

    Anisotropic impedance surfaces, which include metasurfaces and high impedance surfaces (HIS), can be designed to control the amplitude and propagation direction of surface electromagnetic waves and are an effective means to enhance the isolation between antennas that share a common ground plane. To date, the majority of metastructures that have been designed for antenna isolation have relied on an isotropic distribution of unit cells that possess a stop band that inhibits the propagation of surface waves between neighboring antennas. A less common approach to isolation has been through the design of a metasurface that enables the re-direction of surface waves away from the location of the antenna structure, which effectively limits the coupling. In this paper, we discuss results from our computational investigation associated with improving antenna isolation through the use of an anisotropic metastructure. Simulated results associated with the isolation performance of two simple, but similar, anisotropic structures are compared to the corresponding results from a broadband magnetic radar absorbing materials (magRAM).

  18. Metamaterial buffer for broadband non-resonant impedance matching of obliquely incident acoustic waves.

    PubMed

    Fleury, Romain; Alù, Andrea

    2014-12-01

    Broadband impedance matching and zero reflection of acoustic waves at a planar interface between two natural materials is a rare phenomenon, unlike its optical counterpart, frequently observed for polarized light incident at the Brewster angle. In this article, it is shown that, by inserting a metamaterial layer between two acoustic materials with different impedance, it is possible to artificially realize an extremely broadband Brewster-like acoustic intromission angle window, in which energy is totally transmitted from one natural medium to the other. The metamaterial buffer, composed of acoustically hard materials with subwavelength tapered apertures, provides an interesting way to match the impedances of two media in a broadband fashion, different from traditional methods like quarter-wave matching or Fabry-Pérot resonances, inherently narrowband due to their resonant nature. This phenomenon may be interesting for a variety of applications including energy harvesting, acoustic imaging, ultrasonic transducer technology, and noise control.

  19. Development of an Acoustic Impedance Tube Testbed for Material Sample Testing

    NASA Technical Reports Server (NTRS)

    Doty, Benjamin J.; Kolaini, Ali R.

    2012-01-01

    Acoustic impedance tube method: uses Traveling wave amplitudes are measured on either side of a sample in a tube. Many acoustic properties of the sample can be calculated. It is Simple and inexpensive to set up, ideal for high volume optimization tests

  20. The use of electro-acoustic impedance measurements in detecting early clinical otosclerosis.

    PubMed

    Van Wagoner, R S; Campbell, J D

    1976-02-01

    The first evidence that sodium fluoride (NaFl) can stop the otosclerotic process was recently presented. This development has placed new emphasis on the early detection of clinical otosclerosis. Electro-acoustic impedance measurements often detect minute changes in absolute impedance and compliance of the ossicular chain. The most valuable diagnostic information, however, is a negative on-off (biphasic) type of acoustic reflex. These results are often evident prior to the detection of positive clinical signs of otosclerosis. The negative on-off acoustic reflex is reviewed in this paper along with case discussions involving medical/surgical management of early otosclerosis.

  1. Contribution to classification of buried objects based on acoustic impedance matching.

    PubMed

    Stepanić, J; Wüstenberg, H; Krstelj, V; Mrasek, H

    2003-03-01

    Determination of material the buried objects are made of could contribute significantly to their recognition, or classification. This is important in detecting buried antipersonnel landmines within the context of humanitarian demining, as well as in a variety of other applications. In this article the concept has been formulated of the approach to buried object's material determination starting with ultrasonic impulse propagation analysis in a particular testing set configuration. The impulse propagates through a characterized transfer material in such a way that a part of it, a reflected wave, carries the information about the buried object's surface material acoustic impedance. The limit of resolution capability is theoretically analyzed and experimentally evaluated and the influencing factors described. Among these, the contact between clean surfaces of the transfer material and buried object is emphasized.

  2. Input impedance matching of acoustic transducers operating at off-resonant frequencies.

    PubMed

    Son, Kyu Tak; Lee, Chin C

    2010-12-01

    The input impedance matching technique of acoustic transducers at off-resonant frequencies is reported. It uses an inherent impedance property of transducers and thus does not need an external electric matching circuit or extra acoustic matching section. The input electrical equivalent circuit includes a radiation component and a dielectric capacitor. The radiation component consists of a radiation resistance and a radiation reactance. The total reactance is the sum of the radiation reactance and the dielectric capacitive reactance. This reactance becomes zero at two frequencies where the impedance is real. The transducer size can be properly chosen so that the impedance at one of the zero-crossing frequencies is close to 50 Ω, the output impedance of signal generators. At this off-resonant operating frequency, the reflection coefficient of the transducer is minimized without using any matching circuit. Other than the size, the impedance can also be fine tuned by adjusting the thickness of material that bonds the transducer plate to the substrates. The acoustic impedance of the substrate and that of the bonding material can also be used as design elements in the transducer structure to achieve better transducer matching. Lead titanate piezoelectric plates were bonded on Lucite, liquid crystal polymer (LCP), and bismuth (Bi) substrates to produce various transducer structures. Their input impedance was simulated using a transducer model and compared with measured values to illustrate the matching principle.

  3. Duct wall impedance control as an advanced concept for acoustic impression

    NASA Technical Reports Server (NTRS)

    Dean, P. D.; Tester, B. J.

    1975-01-01

    Models and tests on an acoustic duct liner system which has the property of controlled-variable acoustic impedance are described. This is achieved by a novel concept which uses the effect of steady air flow through a multi-layer, locally reacting, resonant-cavity absorber. The scope of this work was limited to a 'proof of concept.' The test of the concept was implemented by means of a small-scale, square-section flow duct facility designed specifically for acoustic measurements, with one side of the duct acoustically lined. The test liners were designed with the aid of previously established duct acoustic theory and a semi-empirical impedance model of the liner system. Over the limited range tested, the liner behaved primarily as predicted, exhibiting significant changes in resistance and reactance, thus providing the necessary concept validation.

  4. An investigation of the diffraction of an acoustic plane wave by a curved surface of finite impedance. Ph.D. Thesis Final Technical Report, 1 Feb. 1985 - 1 Sep. 1989

    NASA Technical Reports Server (NTRS)

    Kearns, James A.

    1989-01-01

    Phenomena associated with long range propagation of sound over irregular topography motivated this work, which was to analyze the diffraction effects which would occur near the tops of hills and ridges. The diffraction of a high frequency plane wave due to its grazing of a two-dimensional curved surface of finite impedance was also studied. Laboratory scale models were constructed and measurements were made of the field on, above, and behind either of two curved surfaces possessing distinctly different impedances; that is, one was soft while the other was hard. The experimental technique consisted of simultaneously measuring the pressure at a reference point and at a field point due to a transient pulse generated by an electric spark. The pressure waveforms were digitized and processed. The ratio of the discrete Fourier transforms of the two waveforms provided an estimate of the insertion loss between them. The results of the measurements were compared with the predictions of a theory which was derived by Pierce using the method of Matched Asymptotic Expansions (MAE). The predictions relied upon the experimental evaluation of the impedance of each surface at grazing angles of incidence. This evaluation was achieved by a fairly standard technique involving empirical models of various generic types of surfaces. An example was shown of the important role that the structural intricacies of a surface play in the determination of an appropriate model. The comparison between the measurements and predictions indicated that the theory gives an excellent description of the field anywhere near a curved surface. Further, with a simple modification, the theory was also shown to give nearly as good of a description of the field surrounding a curved surface even at distances far behind the surface yet near the line of sight.

  5. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

    Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

    1994-01-01

    A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

  6. Acoustic input impedance of the avian inner ear measured in ostrich (Struthio camelus).

    PubMed

    Muyshondt, Pieter G G; Aerts, Peter; Dirckx, Joris J J

    2016-09-01

    In both mammals and birds, the mechanical behavior of the middle ear structures is affected by the mechanical impedance of the inner ear. In this study, the aim was to quantify the acoustic impedance of the avian inner ear in the ostrich, which allows us to determine the effect on columellar vibrations and middle ear power flow in future studies. To determine the inner ear impedance, vibrations of the columella were measured for both the quasi-static and acoustic stimulus frequencies. In the frequency range of 0.3-4 kHz, we used electromagnetic stimulation of the ossicle and a laser Doppler vibrometer to measure the vibration response. At low frequencies, harmonic displacements were imposed on the columella using piezo stimulation and the resulting force response was measured with a force sensor. From these measurement data, the acoustic impedance of the inner ear could be determined. A simple RLC model in series of the impedance measurements resulted in a stiffness reactance of KIE = 0.20·10(12) Pa/m³, an inertial impedance of MIE = 0.652·10(6) Pa s(2)/m³, and a resistance of RIE = 1.57·10(9) Pa s/m. We found that values of the inner ear impedance in the ostrich are one to two orders in magnitude smaller than what is found in mammal ears.

  7. Analogy electromagnetism-acoustics: Validation and application to local impedance active control for sound absorption

    NASA Astrophysics Data System (ADS)

    Nicolas, L.; Furstoss, M.; Galland, M. A.

    1998-10-01

    An analogy between electromagnetism and acoustics is presented in 2D. The propagation of sound in presence of absorbing material is modeled using an open boundary microwave package. Validation is performed through analytical and experimental results. Application to local impedance active control for free field sound absorption is finally described. Une analogie entre acoustique et électromagnétisme est présentée en 2D, afin de modéliser la propagation d'ondes acoustiques, en présence de matériau absorbant et à l'aide d'un logiciel de micro-ondes en domaine ouvert. Cette analogie est validée par des résultats analytiques et expérimentaux. Une application au contrôle actif de l'impédance acoustique de surface de matériaux poreux est finalement décrite.

  8. Duct wall impedance control as an advanced concept for acoustic suppression enhancement. [engine noise reduction

    NASA Technical Reports Server (NTRS)

    Dean, P. D.

    1978-01-01

    A systems concept procedure is described for the optimization of acoustic duct liner design for both uniform and multisegment types. The concept was implemented by the use of a double reverberant chamber flow duct facility coupled with sophisticated computer control and acoustic analysis systems. The optimization procedure for liner insertion loss was based on the concept of variable liner impedance produced by bias air flow through a multilayer, resonant cavity liner. A multiple microphone technique for in situ wall impedance measurements was used and successfully adapted to produce automated measurements for all liner configurations tested. The complete validation of the systems concept was prevented by the inability to optimize the insertion loss using bias flow induced wall impedance changes. This inability appeared to be a direct function of the presence of a higher order energy carrying modes which were not influenced significantly by the wall impedance changes.

  9. Appraisal of broadband acoustic impedances from first principles and band-limited seismic reflection data

    NASA Astrophysics Data System (ADS)

    Mandal, A.; Ghosh, S. K.

    2015-12-01

    Seismic derived acoustic impedance is an essential output for the quantitative interpretation of seismic data. However, the band limitation of seismic data leads to a nonunique estimate of the acoustic impedance profile. The prevalent methods counter the nonuniqueness either by stabilizing the answer with respect to an initial model or by resorting to an assumption of certain criterion such as sparsity of the reflection coefficients. Making a nominal assumption of a homogeneous layered earth model, we formulate a set of linear equations where the reflection coefficients are the unknowns and the recursively integrated seismic trace constitutes the data. The approach makes a frontal assault on the problem of reconstructing reflection coefficients from band-limited data and stems from first principles, i.e., Zöppritz's equation in this case. Nonuniqueness is countered in part by the layercake assumption, and in part by the adoption of the singular value decomposition (SVD) method of finding an optimal solution to the set of linear equations, provided the objective is to reconstruct a smoothed version of the impedance profile that includes only its coarser structures. The efficacy of the method has been tested with synthetic data added with significant noise and generated from rudimentary earth models as well as from measured logs of acoustic impedance. Emergence of consistent estimates of impedance from synthetic data generated for several frequency bands increases the confidence in the method. The study also proves the successfulness of the method for (a) an accurate estimate of the impedance mean, (b) an accurate reconstruction of the direct-current (dc) frequency of the reflectivity, and (c) an acceptable reconstruction of the broad trend of the original impedance profile. All these outputs can serve as significant constraints for either more refined inversions or geological interpretations. (Keywords: Reflection data, Acoustic impedance, Broadband, Linear

  10. Acoustics of Jet Surface Interaction - Scrubbing Noise

    NASA Technical Reports Server (NTRS)

    Khavaran, Abbas

    2014-01-01

    Concepts envisioned for the future of civil air transport consist of unconventional propulsion systems in the close proximity to the structure or embedded in the airframe. While such integrated systems are intended to shield noise from the community, they also introduce new sources of sound. Sound generation due to interaction of a jet flow past a nearby solid surface is investigated here using the generalized acoustic analogy theory. The analysis applies to the boundary layer noise generated at and near a wall, and excludes the scattered noise component that is produced at the leading or the trailing edge. While compressibility effects are relatively unimportant at very low Mach numbers, frictional heat generation and thermal gradient normal to the surface could play important roles in generation and propagation of sound in high speed jets of practical interest. A general expression is given for the spectral density of the far field sound as governed by the variable density Pridmore-Brown equation. The propagation Green's function is solved numerically for a high aspect-ratio rectangular jet starting with the boundary conditions on the surface and subject to specified mean velocity and temperature profiles between the surface and the observer. It is shown the magnitude of the Green's function decreases with increasing source frequency and/or jet temperature. The phase remains constant for a rigid surface, but varies with source location when subject to an impedance type boundary condition. The Green's function in the absence of the surface, and flight effects are also investigated

  11. Acoustic phonons, surface plasmons and surface acoustic plasmons in a superlattice and their nonreciprocal device applications

    NASA Astrophysics Data System (ADS)

    Derov, John S.

    1987-05-01

    The literature was surveyed to determine potential applications of acoustic and plasma phenomena in superlattices. The use of folded zone acoustic phonons and acoustic surface plasmons in 3 to 5 compounds like AlGaAs/GaAs superlattices is addressed. A dielectric phonon filter is presented and an acoustic resonator is considered. Surface plasmons and surface acoustic plasmons are discussed and a transducer, delay line and mixer are proposed as applications. A 500 GHz isolator utilizing surface magnetoplasmons is also presented.

  12. Finite difference time domain implementation of surface impedance boundary conditions

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Luebbers, Raymond J.; Yee, Kane S.; Kunz, Karl S.

    1991-01-01

    Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media throughout the solution volume. The standard approach is to approximate the surface impedance over a very small bandwidth by its value at the center frequency, and then use that result in the boundary condition. Two implementations of the surface impedance boundary condition are presented. One implementation is a constant surface impedance boundary condition and the other is a dispersive surface impedance boundary condition that is applicable over a very large frequency bandwidth and over a large range of conductivities. Frequency domain results are presented in one dimension for two conductivity values and are compared with exact results. Scattering width results from an infinite square cylinder are presented as a 2-D demonstration. Extensions to 3-D should be straightforward.

  13. Finite difference time domain implementation of surface impedance boundary conditions

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Luebbers, Raymond J.; Yee, Kane S.; Kunz, Karl S.

    1991-01-01

    Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In the finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media throughout the solution volume. The standard approach is to approximate the surface impedance over a very small bandwidth by its value at the center frequency, and then use that result in the boundary condition. Here, two implementations of the surface impedance boundary condition are presented. One implementation is a constant surface impedance boundary condition and the other is a dispersive surface impedance boundary condition that is applicable over a very large frequency bandwidth and over a large range of conductivities. Frequency domain results are presented in one dimension for two conductivity values and are compared with exact results. Scattering width results from an infinite square cylinder are presented as a two dimensional demonstration. Extensions to three dimensions should be straightforward.

  14. Impedance Analysis of Surface-Bound Biomembranes

    DTIC Science & Technology

    1990-06-08

    and identify by block numb (i FIELD GROUP SUB-GROLm--- AC Impedance, Biomembranes, Lipid, Electrod\\) ’CBiosensor - O ( S. &-’te ,,• J ABSTRACT...Instit-ute 57 Union St., Worcester, MA 01608 ABSTRACTElcchria isThe impedance of different electrode substratesElcharacteriz l biomemance atnactuses fomed ...T10 2), indium/tin oxide (ITO) and platinum electrodes that have been "primed" by covalent attachment of long-chained alkyl groups . The electroes were

  15. Surface acoustic wave frequency comb

    NASA Astrophysics Data System (ADS)

    Matsko, A. B.; Savchenkov, A. A.; Ilchenko, V. S.; Seidel, D.; Maleki, L.

    2012-02-01

    We investigate opto-mechanical oscillation (OMO) and subsequent generation of acoustic wave frequency combs in monolithic crystalline whispering gallery mode (WGM) resonators. The OMO is observed in resonators made of electro-optic (lithium tantalate), non-electro-optic birefringent (magnesium fluoride), and non-birefringent (calcium fluoride) materials. The phenomenon manifests itself as generation of optical harmonics separated by the eigenfrequency of a surface acoustic wave (SAW) mechanical mode of the same WGM resonator. We show that the light escaping the resonator and demodulated on a fast photodiode produces a spectrally pure radio frequency (RF) signal. For instance, we demonstrate generation of 200 MHz signals with instantaneous linewidth of 0.2 Hz.

  16. Ground effects of space weather investigated by the surface impedance

    NASA Astrophysics Data System (ADS)

    Pirjola, R.; Boteler, D.; Trichtchenko, L.

    2009-02-01

    The objective of this paper is to provide a discussion of the surface impedance applicable in connection with studies of geomagnetically induced currents (GIC) in technological systems. This viewpoint means that the surface impedance is regarded as a tool to determine the horizontal (geo)electric field at the Earth's surface, which is the key quantity for GIC. Thus the approach is different from the traditional magnetotelluric viewpoint. The definition of the surface impedance usually involves wavenumber-frequency-domain fields, so inverse Fourier transforming the expression of the electric field in terms of the surface impedance and the geomagnetic field results in convolution integrals in the time and space domains. The frequency-dependent surface impedance has a high-pass filter character whereas the corresponding transfer function between the electric field and the time derivative of the magnetic field is of a low-pass filter type. The relative change of the latter transfer function with frequency is usually smaller than that of the surface impedance, which indicates that the geoelectric field is closer to the time derivative than to the magnetic field itself. An investigation of the surface impedance defined by the space-domain electric and magnetic components indicates that the largest electric fields are not always achieved by the plane wave assumption, which is sometimes regarded as an extreme case for GIC. It is also concluded in this paper that it is often possible to apply the plane wave relation locally between the surface electric and magnetic fields. The absolute value of the surface impedance decreases with an increasing wavenumber although the maximum may also be at a non-zero value of the wavenumber. The imaginary part of the surface impedance usually much exceeds the real part.

  17. Underwater asymmetric acoustic transmission structure using the medium with gradient change of impedance

    NASA Astrophysics Data System (ADS)

    Bo, Hu; Jie, Shi; Sheng-Guo, Shi; Yu, Sun; Zhong-Rui, Zhu

    2016-02-01

    We propose an underwater asymmetric acoustic transmission structure comprised of two media each with a gradient change of acoustic impedance. By gradually increasing the acoustic impedances of the media, the propagating direction of the acoustic wave can be continuously bent, resulting in allowing the acoustic wave to pass through along the positive direction and blocking acoustic waves from the negative one. The main advantages of this structure are that the asymmetric transmission effect of this structure can be realized and enhanced more easily in water. We investigate both numerically and experimentally the asymmetric transmission effect. The experimental results show that a highly efficient asymmetric acoustic transmission can be yielded within a remarkable broadband frequency range, which agrees well with the numerical prediction. It is of potential practical significance for various underwater applications such as reducing vibration and noise. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204049 and 11204050), the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT1228), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20122304120023 and 20122304120011).

  18. Alignment of an acoustic manipulation device with cepstral analysis of electronic impedance data.

    PubMed

    Hughes, D A; Qiu, Y; Démoré, C; Weijer, C J; Cochran, S

    2015-02-01

    Acoustic particle manipulation is an emerging technology that uses ultrasonic standing waves to position objects with pressure gradients and acoustic radiation forces. To produce strong standing waves, the transducer and the reflector must be aligned properly such that they are parallel to each other. This can be a difficult process due to the need to visualise the ultrasound waves and as higher frequencies are introduced, this alignment requires higher accuracy. In this paper, we present a method for aligning acoustic resonators with cepstral analysis. This is a simple signal processing technique that requires only the electrical impedance measurement data of the resonator, which is usually recorded during the fabrication process of the device. We first introduce the mathematical basis of cepstral analysis and then demonstrate and validate it using a computer simulation of an acoustic resonator. Finally, the technique is demonstrated experimentally to create many parallel linear traps for 10 μm fluorescent beads inside an acoustic resonator.

  19. Evaluation of Parallel-Element, Variable-Impedance, Broadband Acoustic Liner Concepts

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Howerton, Brian M.; Ayle, Earl

    2012-01-01

    Recent trends in aircraft engine design have highlighted the need for acoustic liners that provide broadband sound absorption with reduced liner thickness. Three such liner concepts are evaluated using the NASA normal incidence tube. Two concepts employ additive manufacturing techniques to fabricate liners with variable chamber depths. The first relies on scrubbing losses within narrow chambers to provide acoustic resistance necessary for sound absorption. The second employs wide chambers that provide minimal resistance, and relies on a perforated sheet to provide acoustic resistance. The variable-depth chambers used in both concepts result in reactance spectra near zero. The third liner concept employs mesh-caps (resistive sheets) embedded at variable depths within adjacent honeycomb chambers to achieve a desired impedance spectrum. Each of these liner concepts is suitable for use as a broadband sound absorber design, and a transmission line model is presented that provides good comparison with their respective acoustic impedance spectra. This model can therefore be used to design acoustic liners to accurately achieve selected impedance spectra. Finally, the effects of increasing the perforated facesheet thickness are demonstrated, and the validity of prediction models based on lumped element and wave propagation approaches is investigated. The lumped element model compares favorably with measured results for liners with thin facesheets, but the wave propagation model provides good comparisons for a wide range of facesheet thicknesses.

  20. Acoustic Propagation and Barrier Diffraction Over an Impedance Plane.

    DTIC Science & Technology

    1982-10-13

    propagation solution into a barrier model so that ground reflections in addition to edge diffraction could be accounted for. Only the first term in the...model so that ground reflections in addition to edge N diffraction could be accounted for. Only the first term in the asymptotic ground propagation... contemporary research needs-particularly those of underwater acoustics as weil as community and aircraft noise control-a re-evaluation of previous results has

  1. Sputtered SiO2 as low acoustic impedance material for Bragg mirror fabrication in BAW resonators.

    PubMed

    Olivares, Jimena; Wegmann, Enrique; Capilla, José; Iborra, Enrique; Clement, Marta; Vergara, Lucía; Aigner, Robert

    2010-01-01

    In this paper we describe the procedure to sputter low acoustic impedance SiO(2) films to be used as a low acoustic impedance layer in Bragg mirrors for BAW resonators. The composition and structure of the material are assessed through infrared absorption spectroscopy. The acoustic properties of the films (mass density and sound velocity) are assessed through X-ray reflectometry and picosecond acoustic spectroscopy. A second measurement of the sound velocity is achieved through the analysis of the longitudinal lambda/2 resonance that appears in these silicon oxide films when used as uppermost layer of an acoustic reflector placed under an AlN-based resonator.

  2. Optimization of Microphone Locations for Acoustic Liner Impedance Eduction

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Watson, W. R.; June, J. C.

    2015-01-01

    Two impedance eduction methods are explored for use with data acquired in the NASA Langley Grazing Flow Impedance Tube. The first is an indirect method based on the convected Helmholtz equation, and the second is a direct method based on the Kumaresan and Tufts algorithm. Synthesized no-flow data, with random jitter to represent measurement error, are used to evaluate a number of possible microphone locations. Statistical approaches are used to evaluate the suitability of each set of microphone locations. Given the computational resources required, small sample statistics are employed for the indirect method. Since the direct method is much less computationally intensive, a Monte Carlo approach is employed to gather its statistics. A comparison of results achieved with full and reduced sets of microphone locations is used to determine which sets of microphone locations are acceptable. For the indirect method, each array that includes microphones in all three regions (upstream and downstream hard wall sections, and liner test section) provides acceptable results, even when as few as eight microphones are employed. The best arrays employ microphones well away from the leading and trailing edges of the liner. The direct method is constrained to use microphones opposite the liner. Although a number of arrays are acceptable, the optimum set employs 14 microphones positioned well away from the leading and trailing edges of the liner. The selected sets of microphone locations are also evaluated with data measured for ceramic tubular and perforate-over-honeycomb liners at three flow conditions (Mach 0.0, 0.3, and 0.5). They compare favorably with results attained using all 53 microphone locations. Although different optimum microphone locations are selected for the two impedance eduction methods, there is significant overlap. Thus, the union of these two microphone arrays is preferred, as it supports usage of both methods. This array contains 3 microphones in the upstream

  3. Experimental validation of a two-dimensional shear-flow model for determining acoustic impedance

    NASA Technical Reports Server (NTRS)

    Parrott, Tony L.; Watson, Willie R.; Jones, Michael G.

    1987-01-01

    Tests were conducted to validate a two-dimensional shear-flow analytical model for determining the acoustic impedance of a liner test specimen in a grazing-incidence, grazing-flow environment. The tests were limited to a test specimen chosen to exhibit minimal effects of grazing flow so that the results obtained by using the shear-flow analytical model would be expected to match those obtained from normal-incidence impedance measurements. Impedances for both downstream and upstream sound propagation were generally consistent with those from normal-incidence measurements. However, sensitivity of the grazing-incidence impedance to small measurement or systematic errors in propagation constant varied dramatically over the range of test frequencies.

  4. A finite element surface impedance representation for steady-state problems

    NASA Technical Reports Server (NTRS)

    Kalinowski, A. J.

    1986-01-01

    A procedure for determining the scattered pressure field resulting from a monochromatic harmonic wave that is incident upon a layer energy absorbing structure is treated. The situation where the structure is modeled with finite elements and the surrounding acoustic medium (water or air) is represented with either acoustic finite elements, or some type of boundary integral formulation, is considered. Finite element modeling problems arise when the construction of the structure, at the fluid structure interface, are nonhomogeneous and in particular, when the inhomogeneities are small relative to the acoustic wave length. An approximate procedure is presented for replacing the detailed microscopic representation of the layered surface configuration with an equivalent simple surface impedance finite element, which is especially designed to work only at limited frequencies. An example problem is presented using NASTRAN. However, the procedure is general enough to adapt to practically any finite element code having a steady state option.

  5. A finite element propagation model for extracting normal incidence impedance in nonprogressive acoustic wave fields

    NASA Astrophysics Data System (ADS)

    Watson, Willie R.; Jones, Michael G.; Tanner, Sharon E.; Parrott, Tony L.

    1995-04-01

    A propagation model method for extracting the normal incidence impedance of an acoustic material installed as a finite length segment in a wall of a duct carrying a nonprogressive wave field is presented. The method recasts the determination of the unknown impedance as the minimization of the normalized wall pressure error function. A finite element propagation model is combined with a coarse/fine grid impedance plane search technique to extract the impedance of the material. Results are presented for three different materials for which the impedance is known. For each material, the input data required for the prediction scheme was computed from modal theory and then contaminated by random error. The finite element method reproduces the known impedance of each material almost exactly for random errors typical of those found in many measurement environments. Thus, the method developed here provides a means for determining the impedance of materials in a nonprogressirve wave environment such as that usually encountered in a commercial aircraft engine and most laboratory settings.

  6. A Finite Element Propagation Model for Extracting Normal Incidence Impedance in Nonprogressive Acoustic Wave Fields

    NASA Astrophysics Data System (ADS)

    Watson, Willie R.; Jones, Michael G.; Tanner, Sharon E.; Parrott, Tony L.

    1996-04-01

    A propagation model method for extracting the normal incidence impedance of an acoustic material installed as a finite length segment in a wall of a duct carrying a nonprogressive wave field is presented. The method recasts the determination of the unknown impedance as the minimization of the normalized wall pressure error function. A finite element propagation model is combined with a coarse/fine grid impedance plane search technique to extract the impedance of the material. Results are presented for three different materials for which the impedance is known. For each material, the input data required for the prediction scheme were computed from modal theory and then contaminated by random error. The finite element method reproduces the known impedance of each material almost exactly for random errors typical of those found in many measurement environments. Thus, the method developed here provides a means for determining the impedance of materials in a nonprogressive wave environment such as that usually encountered in a commercial aircraft engine and in most laboratory settings.

  7. Acoustic Treatment Design Scaling Methods. Volume 2; Advanced Treatment Impedance Models for High Frequency Ranges

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.; Yu, J.; Kwan, H. W.

    1999-01-01

    The primary purpose of this study is to develop improved models for the acoustic impedance of treatment panels at high frequencies, for application to subscale treatment designs. Effects that cause significant deviation of the impedance from simple geometric scaling are examined in detail, an improved high-frequency impedance model is developed, and the improved model is correlated with high-frequency impedance measurements. Only single-degree-of-freedom honeycomb sandwich resonator panels with either perforated sheet or "linear" wiremesh faceplates are considered. The objective is to understand those effects that cause the simple single-degree-of- freedom resonator panels to deviate at the higher-scaled frequency from the impedance that would be obtained at the corresponding full-scale frequency. This will allow the subscale panel to be designed to achieve a specified impedance spectrum over at least a limited range of frequencies. An advanced impedance prediction model has been developed that accounts for some of the known effects at high frequency that have previously been ignored as a small source of error for full-scale frequency ranges.

  8. Evaluation of a multi-point method for determining acoustic impedance

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Parrott, Tony L.

    1988-01-01

    An investigation was conducted to explore potential improvements provided by a Multi-Point Method (MPM) over the Standing Wave Method (SWM) and Two-Microphone Method (TMM) for determining acoustic impedance. A wave propagation model was developed to model the standing wave pattern in an impedance tube. The acoustic impedance of a test specimen was calculated from a best fit of this standing wave pattern to pressure measurements obtained along the impedance tube centerline. Three measurement spacing distributions were examined: uniform, random, and selective. Calculated standing wave patterns match the point pressure measurement distributions with good agreement for a reflection factor magnitude range of 0.004 to 0.999. Comparisons of results using 2, 3, 6, and 18 measurement points showed that the most consistent results are obtained when using at least 6 evenly spaced pressure measurements per half-wavelength. Also, data were acquired with broadband noise added to the discrete frequency noise and impedances were calculated using the MPM and TMM algorithms. The results indicate that the MPM will be superior to the TMM in the presence of significant broadband noise levels associated with mean flow.

  9. Multi-stage pulse tube cryocooler with acoustic impedance constructed to reduce transient cool down time and thermal loss

    NASA Technical Reports Server (NTRS)

    Gedeon, David R. (Inventor); Wilson, Kyle B. (Inventor)

    2008-01-01

    The cool down time for a multi-stage, pulse tube cryocooler is reduced by configuring at least a portion of the acoustic impedance of a selected stage, higher than the first stage, so that it surrounds the cold head of the selected stage. The surrounding acoustic impedance of the selected stage is mounted in thermally conductive connection to the warm region of the selected stage for cooling the acoustic impedance and is fabricated of a high thermal diffusivity, low thermal radiation emissivity material, preferably aluminum.

  10. Influence of exit impedance on finite difference solutions of transient acoustic mode propagation in ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1981-01-01

    The cutoff mode instability problem associated with a transient finite difference solution to the wave equation is explained. The steady-state impedance boundary condition is found to produce acoustic reflections during the initial transient, which cause finite instabilities in the cutoff modes. The stability problem is resolved by extending the duct length to prevent transient reflections. Numerical calculations are presented at forcing frequencies above, below, and nearly at the cutoff frequency, and exit impedance models are presented for use in the practical design of turbofan inlets.

  11. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.

    1978-01-01

    A number of 401.2 MHz surface acoustic wave (SAW) controlled oscillators were built and tested. The performance of these oscillators was evaluated for possible use as stable oscillators in communication systems. A short term frequency stability of better than 1 x 10 to the minus 9th power for one second was measured for the SAW oscillators. Long term frequency drift was measured and was found to be dependent on SAW design and packaging. Drift rates ranging from 15 ppm in twenty weeks to 2.5 ppm in twenty weeks were observed. Some further improvement was required. The temperature dependence of the saw oscillators was evaluated and it was concluded that some form of temperature compensation will be necessary to meet the requirements of some communication systems.

  12. Swimming Using Surface Acoustic Waves

    PubMed Central

    Bourquin, Yannyk; Cooper, Jonathan M.

    2013-01-01

    Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel. PMID:23431358

  13. Swimming using surface acoustic waves.

    PubMed

    Bourquin, Yannyk; Cooper, Jonathan M

    2013-01-01

    Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel.

  14. Applications of surface acoustic and shallow bulk acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Campbell, Colin K.

    1989-10-01

    Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport; and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings, and oscillators with enhanced performance and capability.

  15. Acoustic impedance matching of piezoelectric transducers to the air.

    PubMed

    Gómez Alvarez-Arenas, Tomás E

    2004-05-01

    The purpose of this work is threefold: to investigate material requirements to produce impedance matching layers for air-coupled piezoelectric transducers, to identify materials that meet these requirements, and to propose the best solution to produce air-coupled piezoelectric transducers for the low megahertz frequency range. Toward this end, design criteria for the matching layers and possible configurations are reviewed. Among the several factors that affect the efficiency of the matching layer, the importance of attenuation is pointed out. A standard characterization procedure is applied to a wide collection of candidate materials to produce matching layers. In particular, some types of filtration membranes are studied. From these results, the best materials are identified, and the better matching configuration is proposed. Four pairs of air-coupled piezoelectric transducers also are produced to illustrate the performance of the proposed solution. The lowest two-way insertion loss figure is -24 dB obtained at 0.45 MHz. This increases for higher frequency transducers up to -42 dB at 1.8 MHz and -50 at 2.25 MHz. Typical bandwidth is about 15-20%.

  16. Probing Acoustic Nonlinearity by Mixing Surface Acoustic Waves

    SciTech Connect

    Hurley, David Howard; Telschow, Kenneth Louis

    2000-07-01

    Measurement methods aimed at determining material properties through nonlinear wave propagation are sensitive to artifacts caused by background nonlinearities inherent in the ultrasonic generation and detection methods. The focus of this paper is to describe our investigation of nonlinear mixing of surface acoustic waves (SAWs) as a means to decrease sensitivity to background nonlinearity and increase spatial sensitivity to acoustic nonlinearity induced by material microstructure.

  17. Multiscale analysis of the acoustic scattering by many scatterers of impedance type

    NASA Astrophysics Data System (ADS)

    Challa, Durga Prasad; Sini, Mourad

    2016-06-01

    We are concerned with the acoustic scattering problem, at a frequency {κ}, by many small obstacles of arbitrary shapes with impedance boundary condition. These scatterers are assumed to be included in a bounded domain {Ω} in {{R}^3} which is embedded in an acoustic background characterized by an eventually locally varying index of refraction. The collection of the scatterers {D_m, m=1,ldots,M} is modeled by four parameters: their number M, their maximum radius a, their minimum distance d and the surface impedances {λ_m, m=1,ldots,M}. We consider the parameters M, d and {λ_m}'s having the following scaling properties: {M:=M(a)=O(a^{-s}), d:=d(a)≈ a^t} and {λ_m:=λ_m(a)=λ_{m,0}a^{-β}}, as {a→ 0}, with non negative constants s, t and {β} and complex numbers {λ_{m, 0}}'s with eventually negative imaginary parts. We derive the asymptotic expansion of the far-fields with explicit error estimate in terms of a, as {a→ 0}. The dominant term is the Foldy-Lax field corresponding to the scattering by the point-like scatterers located at the centers {z_m}'s of the scatterers {D_m}'s with {λ_m \\vert partial D_m\\vert} as the related scattering coefficients. This asymptotic expansion is justified under the following conditions a ≤ a_0, \\vert Re (λ_{m,0})\\vert ≥ λ_-,quad \\vertλ_{m,0}\\vert ≤ λ_+,quad β < 1,quad 0 ≤ s ≤2-β,quads/3 ≤ t and the error of the approximation is {C a^{3-2β-s}}, as {a → 0}, where the positive constants {a_0, λ_-,λ_+} and C depend only on the a priori uniform bounds of the Lipschitz characters of the obstacles {D_m}'s and the ones of {M(a)a^s} and {d(a)/a^t}. We do not assume the periodicity in distributing the small scatterers. In addition, the scatterers can be arbitrary close since t can be arbitrary large, i.e., we can handle the mesoscale regime. Finally, for spherical scatterers, we can also allow the limit case {β=1} with a slightly better error of the approximation.

  18. Acoustic impedance studies in Triassic reservoirs in the Netherlands - application to development and exploration

    SciTech Connect

    Griffiths, M.; Ford, J.

    1995-08-01

    Simple and cost effective seismic forward modelling techniques have been used in conjunction with petrophysical and geological data to provide an integrated approach to understanding the seismic response of Triassic gas reservoirs onshore and offshore Netherlands. Analysis shows that for the Volpriehausen Sandstone in the offshore sector a relationship exists between reservoir acoustic impedance and porosity such that an increase in porosity leads to a decrease in acoustic impedance. Data can be sub-divided on the basis of fluid fill and cementation with trends for both gas and water cases. Regression analysis has defined the optimum relationship for each fluid case and these relationships have been used to predict the acoustic impedance profiles for a variety of reservoir scenarios. Modelling shows that the highest seismic amplitudes and the greatest relative amplitude variation with fluid fill are related to high porosity reservoir. In the onshore sector, analysis for the Roet Sandstone has shown that even small scale variations in reservoir properties can be recorded within the detail of the seismic response. Results from seismic forward modelling compare with amplitude variations observed in real data and suggest that, within the limitations of the dataset and methodology, the technique can be used to predict reservoir attributes from the seismic response. So far, the technique has been sucessfully applied to both exploration and field development projects.

  19. Nonlinear Acoustics at the Air-Water Free Surface

    NASA Astrophysics Data System (ADS)

    Pree, Seth; Naranjo, Brian; Putterman, Seth

    2016-11-01

    According to linear acoustics, airborne sound incident on a water surface transmits only a tenth of a percent of its energy. This difficulty of transmitting energy across the water surface limits the feasibility of standoff ultrasound imaging. We propose to overcome this long standing problem by developing new methods of coupling into the medium at standoff. In particular, we believe that the acoustic nonlinearity of both the air and the medium may yield a range of effects in the vicinity of the surface permitting an efficient transmission of ultrasound from the air into the medium. The recent commercial availability of parametric speakers that deliver modulated 100kHz ultrasound at 135dB to nonlinearly generate music at 95dB provides an interesting platform with which to revisit the transmission of sound across acoustic impedance mismatches. We show results of experimental studies of the behavior of the air-water free surface when subjected to large amplitude acoustic pressures from the air. This work was supported by the ARO STIR program.

  20. Comparison of Acoustic Impedance Eduction Techniques for Locally-Reacting Liners

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Parrott, T. L.; Watson, W. R.

    2003-01-01

    Typical acoustic liners used in current aircraft inlets and aft-fan ducts consist of some type of perforated facesheet bonded to a honeycomb core. A number of techniques for determining the acoustic impedance of these locallyreacting liners have been developed over the last five decades. In addition, a number of models have been developed to predict the acoustic impedance of locallyreacting liners in the presence of grazing flow, and to use that information together with aeroacoustic propagation codes to assess the noise absorption provided by these liners. These prediction models have incorporated the results from databases acquired with specific impedance eduction techniques. Thus, while these prediction models are acceptable for liners that are similar to those tested in these databases, their application to new liner configurations must be viewed with caution. The primary purpose of this paper is to provide a comparison of impedance eduction techniques that have been implemented at various aerospace research laboratories in the United States (NASA Langley Research Center, General Electric Aircraft Engines, B. F. Goodrich and Boeing). A secondary purpose is to provide data for liner configurations that extend the porosity range beyond that which has been previously used in common aircraft engine nacelles. Two sets of liners were designed to study the effects of three parameters: perforate hole diameter, facesheet thickness and porosity. These two sets of liners were constructed for testing in each of the laboratories listed above. The first set of liners was designed to fit into the NASA Langley and Boeing test facilities. The second set was designed to fit into the General Electric Aircraft Engines and B. F. Goodrich test facilities. By using the same parent material, both sets of liners were identical to within the limits of material and fabrication variability. Baseline data were obtained in the normal incidence impedance tubes at NASA Langley and B. F

  1. Planetary surface research with acoustic sounding

    NASA Astrophysics Data System (ADS)

    Krause, C.; Seidensticker, K. J.

    2007-08-01

    Planetary space missions like Rosetta and ExoMars put more and more emphasis on the in-situ investigation of planetary surfaces. The use of mechanical vibrations in the audible frequency range provide a new means to study the structure and properties of the surface layers of terrestrial planets and minor bodies like comets. As the first of this new type of instruments, the Comet Acoustic Surface Sounding Experiment (CASSE) on the Rosetta Lander Philae intends to determine elastic parameters and the structure of the surface layer of the target comet. One drawback of CASSE is unknown possibly weak coupling to the cometary surface. A DFG project is being conducted at the DLR - Deutsches Zentrum für Luft- und Raumfahrt - to test the applicability of planetary penetration instruments like PLUTO, planetary sampling tool, developed for the Mars Express lander Beagle 2, or MUPUS, a heat probe instrument also on Philae, as stronger acoustic sources as well as to develop new methods for the analysis of acoustic data. From the analysis of the polarisation of the recorded acoustic signals it is possible to separate the mixture of different propagating wave types. These identified waves can be used for the determination of mechanical soil properties and near-surface layering. We also will present how acoustic receivers can be used to locate acoustic penetrators or nearby seismic sources using the travel time and/or the polarisation of the acoustic waves.

  2. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2013-05-07

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  3. High-frequency shear-horizontal surface acoustic wave sensor

    DOEpatents

    Branch, Darren W

    2014-03-11

    A Love wave sensor uses a single-phase unidirectional interdigital transducer (IDT) on a piezoelectric substrate for leaky surface acoustic wave generation. The IDT design minimizes propagation losses, bulk wave interferences, provides a highly linear phase response, and eliminates the need for impedance matching. As an example, a high frequency (.about.300-400 MHz) surface acoustic wave (SAW) transducer enables efficient excitation of shear-horizontal waves on 36.degree. Y-cut lithium tantalate (LTO) giving a highly linear phase response (2.8.degree. P-P). The sensor has the ability to detect at the pg/mm.sup.2 level and can perform multi-analyte detection in real-time. The sensor can be used for rapid autonomous detection of pathogenic microorganisms and bioagents by field deployable platforms.

  4. Reducing extrinsic damping of surface acoustic waves at gigahertz frequencies

    NASA Astrophysics Data System (ADS)

    Gelda, Dhruv; Sadhu, Jyothi; Ghossoub, Marc G.; Ertekin, Elif; Sinha, Sanjiv

    2016-04-01

    High-frequency surface acoustic waves (SAWs) in the gigahertz range can be generated using absorption from an ultrafast laser in a patterned metallic grating on a substrate. Reducing the attenuation at these frequencies can yield better sensors as well as enable them to better probe phonon and electron-phonon interactions near surfaces. It is not clear from existing experiments which mechanisms dominate damping at high frequencies. We calculate damping times of SAWs due to various mechanisms in the 1-100 GHz range to find that mechanical loading of the grating on the substrate dominates dissipation by radiating energy from the surface into the bulk. To overcome this and enable future measurements to probe intrinsic damping, we propose incorporating distributed acoustic Bragg reflectors in the experimental structure. Layers of alternating materials with contrasting acoustic impedances embedded a wavelength away from the surface serve to reflect energy back to the surface. Using numerical simulations, we show that a single Bragg reflector is sufficient to increase the energy density at the surface by more than five times. We quantify the resulting damping time to find that it is longer than the intrinsic damping time. The proposed structure can enable future measurements of intrinsic damping in SAWs at ˜100 GHz.

  5. Influence of exit impedance on finite difference solutions of transient acoustic mode propagation in ducts

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.

    1981-01-01

    The time-dependent governing acoustic-difference equations and boundary conditions are developed and solved for sound propagation in an axisymmetric (cylindrical) hard-wall duct without flow and with spinning acoustic modes. The analysis begins with a harmonic sound source radiating into a quiescent duct. This explicit iteration method then calculates stepwise in real time to obtain the steady solutions of the acoustic field. The transient method did not converge to the steady-state solution for cutoff acoustic duct modes. This has implications as to its use in a variable-area duct, where modes may become cutoff in the smal-area portion of the duct. For single cutoff mode propagation the steady-state impedance boundary condition produced acoustic reflections during the initial transient that caused finite instabilities in the numerical calculations. The stability problem is resolved by reformulating the exit boundary condition. Example calculations show good agreement with exact analytical and numerical results for forcing frequencies above, below, and nearly at the cutoff frequency.

  6. Measurements and computational fluid dynamics predictions of the acoustic impedance of orifices

    NASA Astrophysics Data System (ADS)

    Su, J.; Rupp, J.; Garmory, A.; Carrotte, J. F.

    2015-09-01

    The response of orifices to incident acoustic waves, which is important for many engineering applications, is investigated with an approach combining both experimental measurements and numerical simulations. This paper presents experimental data on acoustic impedance of orifices, which is subsequently used for validation of a numerical technique developed for the purpose of predicting the acoustic response of a range of geometries with moderate computational cost. Measurements are conducted for orifices with length to diameter ratios, L/D, of 0.5, 5 and 10. The experimental data is obtained for a range of frequencies using a configuration in which a mean (or bias) flow passes from a duct through the test orifices before issuing into a plenum. Acoustic waves are provided by a sound generator on the upstream side of the orifices. Computational fluid dynamics (CFD) calculations of the same configuration have also been performed. These have been undertaken using an unsteady Reynolds averaged Navier-Stokes (URANS) approach with a pressure based compressible formulation with appropriate characteristic based boundary conditions to simulate the correct acoustic behaviour at the boundaries. The CFD predictions are in very good agreement with the experimental data, predicting the correct trend with both frequency and orifice L/D in a way not seen with analytical models. The CFD was also able to successfully predict a negative resistance, and hence a reflection coefficient greater than unity for the L / D = 0.5 case.

  7. An analytic model for acoustic scattering from an impedance cylinder placed normal to an impedance plane

    NASA Astrophysics Data System (ADS)

    Swearingen, Michelle Elaine

    2003-10-01

    This thesis is a presentation of an analytic model, developed in cylindrical coordinates, for the scattering of a spherical wave off a semi infinite right cylinder placed normal to a ground surface. The model is developed to simulate a single tree and is developed as a first piece to creating a model for estimating attenuation in a forest based on scattering from individual tree trunks. Comparisons are made to the plane wave case, the transparent cylinder case, and the rigid and soft ground cases as a method of theoretically verifying the model. Agreement is excellent for these benchmark cases. Model sensitivity to five parameters is determined, which aids in error analysis, particularly when comparing the model results to experimental data, and offers insight into the inner workings of the model. An experiment was performed to collect real-world data on scattering from a cylinder normal to a ground surface. The data from the experiment is analyzed with a transfer function method into frequency and impulse responses. The model results are compared to the experimental data.

  8. Acoustic microscope surface inspection system and method

    DOEpatents

    Khuri-Yakub, Butrus T.; Parent, Philippe; Reinholdtsen, Paul A.

    1991-01-01

    An acoustic microscope surface inspection system and method in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respected to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations.

  9. Acoustic microscope surface inspection system and method

    DOEpatents

    Khuri-Yakub, B.T.; Parent, P.; Reinholdtsen, P.A.

    1991-02-26

    An acoustic microscope surface inspection system and method are described in which pulses of high frequency electrical energy are applied to a transducer which forms and focuses acoustic energy onto a selected location on the surface of an object and receives energy from the location and generates electrical pulses. The phase of the high frequency electrical signal pulses are stepped with respect to the phase of a reference signal at said location. An output signal is generated which is indicative of the surface of said selected location. The object is scanned to provide output signals representative of the surface at a plurality of surface locations. 7 figures.

  10. Wave-number-based assessment of the doubly asymptotic approximation. I. Frequency domain wet surface impedance

    PubMed

    Ginsberg

    2000-04-01

    The doubly asymptotic approximation (DAA) is a canonical relationship for the interaction between surface normal velocity and pressure. Its validity for a slender hemicapped cylinder is examined by formulating a frequency domain version of DAA using the global basis functions employed in the wave-number-based formulation of the surface variational principle [K. Wu and J. H. Ginsberg, ASME J. Vib. Acoust. 120, 392-400 (1998)]. The wet surface impedance matrix, which relates the spectral representation of normal velocity to a corresponding representation of pressure, is obtained according to a second-order version of DAA and according to the surface variational principle. Comparison and interpretation of the results reveals that DAA fails to account for highlights associated with transition from supersonic to subsonic surface waves as the surface wavelength decreases with frequency held constant.

  11. Antenna pattern control using impedance surfaces

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Liu, Kefeng

    1993-01-01

    A hybrid numerical technique is developed for electrically large pyramidal horn antennas radiating in free space. A stepped-waveguide method is used to analyze the interior surfaces of the horn transition. The Electric Field Integral Equation (EFIE) is employed on the outer surfaces of the pyramidal horn including the radiating aperture. Meanwhile, the Magnetic Field Integral Equation (MFIE) is used on the aperture to relate the aperture fields and those in the horn transition. The resultant hybrid field integral equation (HFIE) is solved numerically by the method of moments. This formulation is both accurate and numerically stable so that high-gain microwave pyramidal horns can be analyzed rigorously. Far-field radiation patterns, both computed and measured, are presented for three electrically-large x-band horn antennas. The comparisons demonstrate that this method is accurate enough to predict the fine pattern structure at wide angles and in the back region. Computed far-field patterns and aperture field distribution of two smaller x-band horns are also presented along with a discussion on the validity of the approximate aperture field distributions routinely used in the analysis and design of pyramidal horns.

  12. Characterizing the ear canal acoustic impedance and reflectance by pole-zero fitting.

    PubMed

    Robinson, Sarah R; Nguyen, Cac T; Allen, Jont B

    2013-07-01

    This study characterizes middle ear complex acoustic reflectance (CAR) and impedance by fitting poles and zeros to real-ear measurements. The goal of this work is to establish a quantitative connection between pole-zero locations and the underlying physical properties of CAR data. Most previous studies have analyzed CAR magnitude; while the magnitude accounts for reflected power, it does not encode latency information. Thus, an analysis that studies the real and imaginary parts of the data together, being more general, should be more powerful. Pole-zero fitting of CAR data is examined using data compiled from various studies, dating back to Voss and Allen (1994). Recent CAR measurements were taken using the Mimosa Acoustics HearID system, which makes complex acoustic impedance and reflectance measurements in the ear canal over a 0.2-6.0 [kHz] frequency range. Pole-zero fits to measurements over this range are achieved with an average RMS relative error of less than 3% with 12 poles. Factoring the reflectance fit into its all-pass and minimum-phase components estimates the effect of the residual ear canal, allowing for comparison of the eardrum impedance and admittance across measurements. It was found that individual CAR magnitude variations for normal middle ears in the 1-4 [kHz] range often give rise to closely-placed pole-zero pairs, and that the locations of the poles and zeros in the s-plane may systematically differ between normal and pathological middle ears. This study establishes a methodology for examining the physical and mathematical properties of CAR using a concise parametric model. Pole-zero modeling accurately parameterizes CAR data, providing a foundation for detection and identification of middle ear pathologies. This article is part of a special issue entitled "MEMRO 2012".

  13. Writing magnetic patterns with surface acoustic waves

    SciTech Connect

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10 μm wide stripes of alternating magnetization and a 3 μm dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  14. Surface acoustic wave dust deposition monitor

    DOEpatents

    Fasching, G.E.; Smith, N.S. Jr.

    1988-02-12

    A system is disclosed for using the attenuation of surface acoustic waves to monitor real time dust deposition rates on surfaces. The system includes a signal generator, a tone-burst generator/amplifier connected to a transmitting transducer for converting electrical signals into acoustic waves. These waves are transmitted through a path defining means adjacent to a layer of dust and then, in turn, transmitted to a receiving transducer for changing the attenuated acoustic wave to electrical signals. The signals representing the attenuated acoustic waves may be amplified and used in a means for analyzing the output signals to produce an output indicative of the dust deposition rates and/or values of dust in the layer. 8 figs.

  15. Broadband gradient impedance matching using an acoustic metamaterial for ultrasonic transducers.

    PubMed

    Li, Zheng; Yang, Dan-Qing; Liu, Shi-Lei; Yu, Si-Yuan; Lu, Ming-Hui; Zhu, Jie; Zhang, Shan-Tao; Zhu, Ming-Wei; Guo, Xia-Sheng; Wu, Hao-Dong; Wang, Xin-Long; Chen, Yan-Feng

    2017-02-17

    High-quality broadband ultrasound transducers yield superior imaging performance in biomedical ultrasonography. However, proper design to perfectly bridge the energy between the active piezoelectric material and the target medium over the operating spectrum is still lacking. Here, we demonstrate a new anisotropic cone-structured acoustic metamaterial matching layer that acts as an inhomogeneous material with gradient acoustic impedance along the ultrasound propagation direction. When sandwiched between the piezoelectric material unit and the target medium, the acoustic metamaterial matching layer provides a broadband window to support extraordinary transmission of ultrasound over a wide frequency range. We fabricated the matching layer by etching the peeled silica optical fibre bundles with hydrofluoric acid solution. The experimental measurement of an ultrasound transducer equipped with this acoustic metamaterial matching layer shows that the corresponding -6 dB bandwidth is able to reach over 100%. This new material fully enables new high-end piezoelectric materials in the construction of high-performance ultrasound transducers and probes, leading to considerably improved resolutions in biomedical ultrasonography and compact harmonic imaging systems.

  16. Broadband gradient impedance matching using an acoustic metamaterial for ultrasonic transducers

    PubMed Central

    Li, Zheng; Yang, Dan-Qing; Liu, Shi-Lei; Yu, Si-Yuan; Lu, Ming-Hui; Zhu, Jie; Zhang, Shan-Tao; Zhu, Ming-Wei; Guo, Xia-Sheng; Wu, Hao-Dong; Wang, Xin-Long; Chen, Yan-Feng

    2017-01-01

    High-quality broadband ultrasound transducers yield superior imaging performance in biomedical ultrasonography. However, proper design to perfectly bridge the energy between the active piezoelectric material and the target medium over the operating spectrum is still lacking. Here, we demonstrate a new anisotropic cone-structured acoustic metamaterial matching layer that acts as an inhomogeneous material with gradient acoustic impedance along the ultrasound propagation direction. When sandwiched between the piezoelectric material unit and the target medium, the acoustic metamaterial matching layer provides a broadband window to support extraordinary transmission of ultrasound over a wide frequency range. We fabricated the matching layer by etching the peeled silica optical fibre bundles with hydrofluoric acid solution. The experimental measurement of an ultrasound transducer equipped with this acoustic metamaterial matching layer shows that the corresponding −6 dB bandwidth is able to reach over 100%. This new material fully enables new high-end piezoelectric materials in the construction of high-performance ultrasound transducers and probes, leading to considerably improved resolutions in biomedical ultrasonography and compact harmonic imaging systems. PMID:28211510

  17. Broadband gradient impedance matching using an acoustic metamaterial for ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Li, Zheng; Yang, Dan-Qing; Liu, Shi-Lei; Yu, Si-Yuan; Lu, Ming-Hui; Zhu, Jie; Zhang, Shan-Tao; Zhu, Ming-Wei; Guo, Xia-Sheng; Wu, Hao-Dong; Wang, Xin-Long; Chen, Yan-Feng

    2017-02-01

    High-quality broadband ultrasound transducers yield superior imaging performance in biomedical ultrasonography. However, proper design to perfectly bridge the energy between the active piezoelectric material and the target medium over the operating spectrum is still lacking. Here, we demonstrate a new anisotropic cone-structured acoustic metamaterial matching layer that acts as an inhomogeneous material with gradient acoustic impedance along the ultrasound propagation direction. When sandwiched between the piezoelectric material unit and the target medium, the acoustic metamaterial matching layer provides a broadband window to support extraordinary transmission of ultrasound over a wide frequency range. We fabricated the matching layer by etching the peeled silica optical fibre bundles with hydrofluoric acid solution. The experimental measurement of an ultrasound transducer equipped with this acoustic metamaterial matching layer shows that the corresponding ‑6 dB bandwidth is able to reach over 100%. This new material fully enables new high-end piezoelectric materials in the construction of high-performance ultrasound transducers and probes, leading to considerably improved resolutions in biomedical ultrasonography and compact harmonic imaging systems.

  18. Meandered-line antenna with integrated high-impedance surface.

    SciTech Connect

    Forman, Michael A.

    2010-09-01

    A reduced-volume antenna composed of a meandered-line dipole antenna over a finite-width, high-impedance surface is presented. The structure is novel in that the high-impedance surface is implemented with four Sievenpiper via-mushroom unit cells, whose area is optimized to match the meandered-line dipole antenna. The result is an antenna similar in performance to patch antenna but one fourth the area that can be deployed directly on the surface of a conductor. Simulations demonstrate a 3.5 cm ({lambda}/4) square antenna with a bandwidth of 4% and a gain of 4.8 dBi at 2.5 GHz.

  19. Gas sensing with surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Martin, S. J.; Schweizer, K. S.; Ricco, A. J.; Zipperian, T. E.

    1985-03-01

    The use of a ZnO-on-Si surface acoustic wave (SAW) resonator as a gas sensor is discussed. In particular, the sensitivity of the device to organic vapors is examined. The planar nature of the SAW device, in which the acoustic energy is confined to within roughly one acoustic wavelength of the surface, makes the device extremely sensitive to surface perturbations. This characteristic has been exploited in the construction of SAW gas sensors in which the surface wave propagation characteristics are altered by species adsorbed from the ambient gas. The porous nature of the sputtered ZnO film, in conjunction with the microbalance capability of the SAW device, gives the sensor the ability to distinguish molecules on the basis of both size and mass.

  20. A Comparison Study of Normal-Incidence Acoustic Impedance Measurements of a Perforate Liner

    NASA Technical Reports Server (NTRS)

    Schultz, Todd; Liu, Fei; Cattafesta, Louis; Sheplak, Mark; Jones, Michael

    2009-01-01

    The eduction of the acoustic impedance for liner configurations is fundamental to the reduction of noise from modern jet engines. Ultimately, this property must be measured accurately for use in analytical and numerical propagation models of aircraft engine noise. Thus any standardized measurement techniques must be validated by providing reliable and consistent results for different facilities and sample sizes. This paper compares normal-incidence acoustic impedance measurements using the two-microphone method of ten nominally identical individual liner samples from two facilities, namely 50.8 mm and 25.4 mm square waveguides at NASA Langley Research Center and the University of Florida, respectively. The liner chosen for this investigation is a simple single-degree-of-freedom perforate liner with resonance and anti-resonance frequencies near 1.1 kHz and 2.2 kHz, respectively. The results show that the ten measurements have the most variation around the anti-resonance frequency, where statistically significant differences exist between the averaged results from the two facilities. However, the sample-to-sample variation is comparable in magnitude to the predicted cross-sectional area-dependent cavity dissipation differences between facilities, providing evidence that the size of the present samples does not significantly influence the results away from anti-resonance.

  1. Digital PIV Measurements of Acoustic Particle Displacements in a Normal Incidence Impedance Tube

    NASA Technical Reports Server (NTRS)

    Humphreys, William M., Jr.; Bartram, Scott M.; Parrott, Tony L.; Jones, Michael G.

    1998-01-01

    Acoustic particle displacements and velocities inside a normal incidence impedance tube have been successfully measured for a variety of pure tone sound fields using Digital Particle Image Velocimetry (DPIV). The DPIV system utilized two 600-mj Nd:YAG lasers to generate a double-pulsed light sheet synchronized with the sound field and used to illuminate a portion of the oscillatory flow inside the tube. A high resolution (1320 x 1035 pixel), 8-bit camera was used to capture double-exposed images of 2.7-micron hollow silicon dioxide tracer particles inside the tube. Classical spatial autocorrelation analysis techniques were used to ascertain the acoustic particle displacements and associated velocities for various sound field intensities and frequencies. The results show that particle displacements spanning a range of 1-60 microns can be measured for incident sound pressure levels of 100-130 dB and for frequencies spanning 500-1000 Hz. The ability to resolve 1 micron particle displacements at sound pressure levels in the 100 dB range allows the use of DPIV systems for measurement of sound fields at much lower sound pressure levels than had been previously possible. Representative impedance tube data as well as an uncertainty analysis for the measurements are presented.

  2. Surface characterization of nanostructured 'black silicon' using impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Duan, Wenqi; Toor, Fatima

    2016-09-01

    In this work, we utilize electrochemical impedance spectroscopy (EIS) to study the electronic characteristics of nanostructured silicon (Si) fabricated using the metal-assisted chemical etched (MACE) process. The nanostructured Si fabricated using the MACE process results in a density graded surface that reduces the broadband surface reflection of Si making it appear almost black, which coins it the name `black Si' (bSi). We study two bSi samples prepared using varying MACE times (20s and 40s) and a reference bare silicon sample using EIS between 1 MHz and 1 Hz frequencies. At an illumination intensity created with the use of a tungsten lamp source calibrated to output an intensity of 1-Sun (1000 W/m2), the impedance behavior at bias potentials in both the forward and reverse bias ranging between -1 V and 1 V are studied. We also study the effect of illumination wavelength by using bandpass filters at 400 nm and 800 nm. The results indicate that the charge transfer resistance (Rct) decreases as the surface roughness of the electrodes increases and as the illumination wavelength increases. We also find that the constant phase element (CPE) impedance of the electrodes increases with increasing surface roughness. These results will guide our future work on high efficiency bSi solar cells.

  3. Wireless actuation with functional acoustic surfaces

    NASA Astrophysics Data System (ADS)

    Qiu, T.; Palagi, S.; Mark, A. G.; Melde, K.; Adams, F.; Fischer, P.

    2016-11-01

    Miniaturization calls for micro-actuators that can be powered wirelessly and addressed individually. Here, we develop functional surfaces consisting of arrays of acoustically resonant micro-cavities, and we demonstrate their application as two-dimensional wireless actuators. When remotely powered by an acoustic field, the surfaces provide highly directional propulsive forces in fluids through acoustic streaming. A maximal force of ˜0.45 mN is measured on a 4 × 4 mm2 functional surface. The response of the surfaces with bubbles of different sizes is characterized experimentally. This shows a marked peak around the micro-bubbles' resonance frequency, as estimated by both an analytical model and numerical simulations. The strong frequency dependence can be exploited to address different surfaces with different acoustic frequencies, thus achieving wireless actuation with multiple degrees of freedom. The use of the functional surfaces as wireless ready-to-attach actuators is demonstrated by implementing a wireless and bidirectional miniaturized rotary motor, which is 2.6 × 2.6 × 5 mm3 in size and generates a stall torque of ˜0.5 mN.mm. The adoption of micro-structured surfaces as wireless actuators opens new possibilities in the development of miniaturized devices and tools for fluidic environments that are accessible by low intensity ultrasound fields.

  4. Topological charge pump by surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Yi, Zheng; Shi-Ping, Feng; Shi-Jie, Yang

    2016-06-01

    Quantized electron pumping by the surface acoustic wave across barriers created by a sequence of split metal gates is interpreted from the viewpoint of topology. The surface acoustic wave serves as a one-dimensional periodical potential whose energy spectrum possesses the Bloch band structure. The time-dependent phase plays the role of an adiabatic parameter of the Hamiltonian which induces a geometrical phase. The pumping currents are related to the Chern numbers of the filled bands below the Fermi energy. Based on this understanding, we predict a novel effect of quantized but non-monotonous current plateaus simultaneously pumped by two homodromous surface acoustic waves. Project supported by the National Natural Science Foundation of China (Grant No. 11374036) and the National Basic Research Program of China (Grant No. 2012CB821403).

  5. Minimizing the Reflection of Electromagnetic Waves by Surface Impedance.

    DTIC Science & Technology

    1986-07-01

    Chen2’ and G. Crosta3 ,** Technical Summary Report #2942 July 1986 ABSTRACT In an empty halfspace a point source emits electromagnetic waves of fixed...are determined by means of the geometrical optics approximation. An optimization method is used to compute the surface impedance, which minimizes a...given function of the e.m. fields (e.g. the average energy density) at a given observation point . The properties of the functions to be minimized are

  6. Ring waveguide resonator on surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Biryukov, S. V.; Martin, G.; Weihnacht, M.

    2007-04-01

    A simple regular electrode structure for surface acoustic wave (SAW) devices is proposed. The structure consists of an interdigital transducer in the form of a ring placed on the Z cut of a hexagonal piezoelectric crystal. Finite thickness electrodes produce the known slowing effect for a SAW in comparison with this SAW on a free surface. The closed "slow" electrode region with the "fast" surrounding region forms an open waveguide resonator structure with the acoustic field concentrated in the electrode region. If the radius of the structure is large enough for a given wavelength, an acceptable level of radiation losses can be reached. The electrical admittance of such resonator does not have sidelobes.

  7. Evaluation of a Variable-Impedance Ceramic Matrix Composite Acoustic Liner

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Watson, W. R.; Nark, D. M.; Howerton, B. M.

    2014-01-01

    As a result of significant progress in the reduction of fan and jet noise, there is growing concern regarding core noise. One method for achieving core noise reduction is via the use of acoustic liners. However, these liners must be constructed with materials suitable for high temperature environments and should be designed for optimum absorption of the broadband core noise spectrum. This paper presents results of tests conducted in the NASA Langley Liner Technology Facility to evaluate a variable-impedance ceramic matrix composite acoustic liner that offers the potential to achieve each of these goals. One concern is the porosity of the ceramic matrix composite material, and whether this might affect the predictability of liners constructed with this material. Comparisons between two variable-depth liners, one constructed with ceramic matrix composite material and the other constructed via stereolithography, are used to demonstrate this material porosity is not a concern. Also, some interesting observations are noted regarding the orientation of variable-depth liners. Finally, two propagation codes are validated via comparisons of predicted and measured acoustic pressure profiles for a variable-depth liner.

  8. Analysis and design of triple-band high-impedance surface absorber with periodic diversified impedance

    NASA Astrophysics Data System (ADS)

    Rui Zhang, Guo; Heng Zhou, Pei; Bin Zhang, Hui; Bo Zhang, Lin; Liang Xie, Jian; Jiang Deng, Long

    2013-10-01

    In this paper, a triple-band planar absorber with high-impedance surface (HIS) is designed and fabricated. The absorber structure is composed of polyurethane foam sandwiched between a lossy sheet of frequency selective surfaces (FSS) and a perfect electric conductor. The lossy FSS possesses different resistances in a periodic composite unit as compared with typical HIS absorber. Losses in the FSS are introduced by printing the periodic composite square ring pattern on blank stickers using various resistive inks. Physical mechanism of the HIS absorbers is analyzed by equivalent circuit model and electric field distribution studies. The proposed absorber with periodic composite units offers superimposed triple-band absorption as compared with that of the single units having single- or dual-band absorption characteristics. The reflection loss measurements show that the 90% absorption bandwidth of the HIS absorber is increased by 42% by the proposed composite periodic units.

  9. Active micromixer using surface acoustic wave streaming

    SciTech Connect

    Branch; Darren W. , Meyer; Grant D. , Craighead; Harold G.

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  10. A semi-analytical model for the acoustic impedance of finite length circular holes with mean flow

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Morgans, Aimee S.

    2016-12-01

    The acoustic response of a circular hole with mean flow passing through it is highly relevant to Helmholtz resonators, fuel injectors, perforated plates, screens, liners and many other engineering applications. A widely used analytical model [M.S. Howe. "Onthe theory of unsteady high Reynolds number flow through a circular aperture", Proc. of the Royal Soc. A. 366, 1725 (1979), 205-223] which assumes an infinitesimally short hole was recently shown to be insufficient for predicting the impedance of holes with a finite length. In the present work, an analytical model based on Green's function method is developed to take the hole length into consideration for "short" holes. The importance of capturing the modified vortex noise accurately is shown. The vortices shed at the hole inlet edge are convected to the hole outlet and further downstream to form a vortex sheet. This couples with the acoustic waves and this coupling has the potential to generate as well as absorb acoustic energy in the low frequency region. The impedance predicted by this model shows the importance of capturing the path of the shed vortex. When the vortex path is captured accurately, the impedance predictions agree well with previous experimental and CFD results, for example predicting the potential for generation of acoustic energy at higher frequencies. For "long" holes, a simplified model which combines Howe's model with plane acoustic waves within the hole is developed. It is shown that the most important effect in this case is the acoustic non-compactness of the hole.

  11. HIFU scattering by the ribs: constrained optimisation with a complex surface impedance boundary condition

    NASA Astrophysics Data System (ADS)

    Gélat, P.; ter Haar, G.; Saffari, N.

    2014-04-01

    High intensity focused ultrasound (HIFU) enables highly localised, non-invasive tissue ablation and its efficacy has been demonstrated in the treatment of a range of cancers, including those of the kidney, prostate and breast. HIFU offers the ability to treat deep-seated tumours locally, and potentially bears fewer side effects than more established treatment modalities such as resection, chemotherapy and ionising radiation. There remains however a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to ablate tissue at the required foci whilst minimising the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. This sometimes results in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. Previously, a boundary element (BE) approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data [1]. Dissipative mechanisms inside the propagating medium have since been implemented, together with a complex surface impedance condition at the surface of the ribs. A reformulation of the boundary element equations as a constrained optimisation problem was carried out to determine the complex surface velocities of a multi-element HIFU array which generated the acoustic pressure field that best fitted a required acoustic pressure distribution in a least-squares sense. This was done whilst ensuring that an acoustic dose rate parameter at the surface of the ribs was kept below a specified threshold. The methodology was tested at an

  12. A model for the pressure excitation spectrum and acoustic impedance of sound absorbers in the presence of grazing flow

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1973-01-01

    The acoustic impedance of sound absorbers in the presence of grazing flow is essential information when analyzing sound propagation within ducts. A unification of the theory of the nonlinear acoustic resistance of Helmholtz resonators including grazing flow is presented. The nonlinear resistance due to grazing flow is considered to be caused by an exciting pressure spectrum produced by the interaction of the grazing flow and the jets flowing from the resonator orifices. With this exciting pressure spectrum the resonator can be treated in the same manner as a resonator without grazing flow but with an exciting acoustic spectrum.

  13. Absorption of surface acoustic waves by graphene

    NASA Astrophysics Data System (ADS)

    Zhang, S. H.; Xu, W.

    2011-06-01

    We present a theoretical study on interactions of electrons in graphene with surface acoustic waves (SAWs). We find that owing to momentum and energy conservation laws, the electronic transition accompanied by the SAW absorption cannot be achieved via inter-band transition channels in graphene. For graphene, strong absorption of SAWs can be observed in a wide frequency range up to terahertz at room temperature. The intensity of SAW absorption by graphene depends strongly on temperature and can be adjusted by changing the carrier density. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as frequency-tunable SAW devices.

  14. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    PubMed

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations.

  15. Surface acoustic wave propagation in graphene film

    SciTech Connect

    Roshchupkin, Dmitry Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Irzhak, Dmitry; Ortega, Luc; Zizak, Ivo; Erko, Alexei; Tynyshtykbayev, Kurbangali; Insepov, Zinetula

    2015-09-14

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  16. Surface acoustic wave propagation in graphene film

    NASA Astrophysics Data System (ADS)

    Roshchupkin, Dmitry; Ortega, Luc; Zizak, Ivo; Plotitcyna, Olga; Matveev, Viktor; Kononenko, Oleg; Emelin, Evgenii; Erko, Alexei; Tynyshtykbayev, Kurbangali; Irzhak, Dmitry; Insepov, Zinetula

    2015-09-01

    Surface acoustic wave (SAW) propagation in a graphene film on the surface of piezoelectric crystals was studied at the BESSY II synchrotron radiation source. Talbot effect enabled the visualization of the SAW propagation on the crystal surface with the graphene film in a real time mode, and high-resolution x-ray diffraction permitted the determination of the SAW amplitude in the graphene/piezoelectric crystal system. The influence of the SAW on the electrical properties of the graphene film was examined. It was shown that the changing of the SAW amplitude enables controlling the magnitude and direction of current in graphene film on the surface of piezoelectric crystals.

  17. Analogies between the measurement of acoustic impedance via the reaction on the source method and the automatic microwave vector network analyzer technique

    NASA Astrophysics Data System (ADS)

    McLean, James; Sutton, Robert; Post, John

    2003-10-01

    One useful method of acoustic impedance measurement involves the measurement of the electrical impedance ``looking into'' the electrical port of a reciprocal electroacoustic transducer. This reaction on the source method greatly facilitates the measurement of acoustic impedance by borrowing highly refined techniques to measure electrical impedance. It is also well suited for in situ acoustic impedance measurements. In order to accurately determine acoustic impedance from the measured electrical impedance, the characteristics of the transducer must be accurately known, i.e., the characteristics of the transducer must be ``removed'' completely from the data. The measurement of acoustic impedance via the measurement of the reaction on the source is analogous to modern microwave measurements made with an automatic vector network analyzer. The action of the analyzer is described as de-embedding the desired data (such as acoustic impedance) from the raw data. Such measurements are fundamentally substitution measurements in that the transducer's characteristics are determined by measuring a set of reference standards. The reaction on the source method is extended to take advantage of improvements in microwave measurement techniques which allow calibration via imperfect standard loads. This removes one of the principal weaknesses of the method in that the requirement of high-quality reference standards is relaxed.

  18. Effects of grazing flow on the steady-state flow resistance and acoustic impedance of thin porous-faced liners

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Walker, B.

    1978-01-01

    The effects of grazing flow on the steady state flow resistance and acoustic impedance of seven Feltmetal and three Rigimesh thin porous faced liners were studied. The steady-state flow resistance of the ten specimens was measured using standard fluid mechanical experimental techniques. The acoustic impedance was measured using the two microphone method. The principal findings of the study are that the effects of grazing flow were measured and found to be small; small differences were measured between steady-state and acoustic resistance, and a semi-empirical model was derived that correlated the steady-state resistance data of the seven Feltmetal liners and the face sheet reactance of both the Feltmetal and Rigimesh liners.

  19. Acoustic tomography in the atmospheric surface layer

    NASA Astrophysics Data System (ADS)

    Ziemann, A.; Arnold, K.; Raabe, A.

    1999-01-01

    Acoustic tomography is presented as a technique for remote monitoring of meteorological quantities. This method and a special algorithm of analysis can directly produce area-averaged values of meteorological parameters. As a result consistent data will be obtained for validation of numerical atmospheric micro-scale models. Such a measuring system can complement conventional point measurements over different surfaces. The procedure of acoustic tomography uses the horizontal propagation of sound waves in the atmospheric surface layer. Therefore, to provide a general overview of sound propagation under various atmospheric conditions a two-dimensional ray-tracing model according to a modified version of Snell's law is used. The state of the crossed atmosphere can be estimated from measurements of acoustic travel time between sources and receivers at different points. Derivation of area-averaged values of the sound speed and furthermore of air temperature results from the inversion of travel time values for all acoustic paths. Thereby, the applied straight ray two-dimensional tomographic model using SIRT (simultaneous iterative reconstruction technique) is characterised as a method with small computational requirements, satisfactory convergence and stability properties as well as simple handling, especially, during online evaluation.

  20. Extraordinary transmission of gigahertz surface acoustic waves

    PubMed Central

    Mezil, Sylvain; Chonan, Kazuki; Otsuka, Paul H.; Tomoda, Motonobu; Matsuda, Osamu; Lee, Sam H.; Wright, Oliver B.

    2016-01-01

    Extraordinary transmission of waves, i.e. a transmission superior to the amount predicted by geometrical considerations of the aperture alone, has to date only been studied in the bulk. Here we present a new class of extraordinary transmission for waves confined in two dimensions to a flat surface. By means of acoustic numerical simulations in the gigahertz range, corresponding to acoustic wavelengths λ ~ 3–50 μm, we track the transmission of plane surface acoustic wave fronts between two silicon blocks joined by a deeply subwavelength bridge of variable length with or without an attached cavity. Several resonant modes of the structure, both one- and two-dimensional in nature, lead to extraordinary acoustic transmission, in this case with transmission efficiencies, i.e. intensity enhancements, up to ~23 and ~8 in the two respective cases. We show how the cavity shape and bridge size influence the extraordinary transmission efficiency. Applications include new metamaterials and subwavelength imaging. PMID:27640998

  1. Wireless Multiplexed Surface Acoustic Wave Sensors Project

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.

    2014-01-01

    Wireless Surface Acoustic Wave (SAW) Sensor is a new technology for obtaining multiple, real-time measurements under extreme environmental conditions. This project plans to develop a wireless multiplexed sensor system that uses SAW sensors, with no batteries or semiconductors, that are passive and rugged, can operate down to cryogenic temperatures and up to hundreds of degrees C, and can be used to sense a wide variety of parameters over reasonable distances (meters).

  2. Numerical study of acoustophoretic motion of particles in a PDMS microchannel driven by surface acoustic waves

    PubMed Central

    Nama, Nitesh; Barnkob, Rune; Mao, Zhangming; Kähler, Christian J.

    2015-01-01

    We present a numerical study of the acoustophoretic motion of particles suspended in a liquid-filled PDMS microchannel on a lithium niobate substrate acoustically driven by surface acoustic waves. We employ a perturbation approach where the flow variables are divided into first- and second-order fields. We use impedance boundary conditions to model the PDMS microchannel walls and we model the acoustic actuation by a displacement function from the literature based on a numerical study of piezoelectric actuation. Consistent with the type of actuation, the obtained first-order field is a horizontal standing wave that travels vertically from the actuated wall towards the upper PDMS wall. This is in contrast to what is observed in bulk acoustic wave devices. The first-order fields drive the acoustic streaming, as well as the time-averaged acoustic radiation force acting on suspended particles. We analyze the motion of suspended particles driven by the acoustic streaming drag and the radiation force. We examine a range of particle diameters to demonstrate the transition from streaming-drag-dominated acoustophoresis to radiation-force-dominated acoustophoresis. Finally, as an application of our numerical model, we demonstrate the capability to tune the position of the vertical pressure node along the channel width by tuning the phase difference between two incoming surface acoustic waves. PMID:26001199

  3. Numerical study of acoustophoretic motion of particles in a PDMS microchannel driven by surface acoustic waves.

    PubMed

    Nama, Nitesh; Barnkob, Rune; Mao, Zhangming; Kähler, Christian J; Costanzo, Francesco; Huang, Tony Jun

    2015-06-21

    We present a numerical study of the acoustophoretic motion of particles suspended in a liquid-filled PDMS microchannel on a lithium niobate substrate acoustically driven by surface acoustic waves. We employ a perturbation approach where the flow variables are divided into first- and second-order fields. We use impedance boundary conditions to model the PDMS microchannel walls and we model the acoustic actuation by a displacement function from the literature based on a numerical study of piezoelectric actuation. Consistent with the type of actuation, the obtained first-order field is a horizontal standing wave that travels vertically from the actuated wall towards the upper PDMS wall. This is in contrast to what is observed in bulk acoustic wave devices. The first-order fields drive the acoustic streaming, as well as the time-averaged acoustic radiation force acting on suspended particles. We analyze the motion of suspended particles driven by the acoustic streaming drag and the radiation force. We examine a range of particle diameters to demonstrate the transition from streaming-drag-dominated acoustophoresis to radiation-force-dominated acoustophoresis. Finally, as an application of our numerical model, we demonstrate the capability to tune the position of the vertical pressure node along the channel width by tuning the phase difference between two incoming surface acoustic waves.

  4. Surface modes in sheared boundary layers over impedance linings

    NASA Astrophysics Data System (ADS)

    Brambley, E. J.

    2013-08-01

    Surface modes, being duct modes localized close to the duct wall, are analysed within a lined cylindrical duct with uniform flow apart from a thin boundary layer. As well as full numerical solutions of the Pridmore-Brown equation, simplified mathematical models are given where the duct lining and boundary layer are lumped together and modelled using a single boundary condition (a modification of the Myers boundary condition previously proposed by the author), from which a surface mode dispersion relation is derived. For a given frequency, up to six surface modes are shown to exist, rather than the maximum of four for uniform slipping flow. Not only is the different number and behaviour of surface modes important for frequency-domain mode-matching techniques, which depend on having found all relevant modes during matching, but the thin boundary layer is also shown to lead to different convective and absolute stability than for uniform slipping flow. Numerical examples are given comparing the predictions of the surface mode dispersion relation to full solutions of the Pridmore-Brown equation, and the accuracy with which surface modes are predicted is shown to be significantly increased compared with the uniform slipping flow assumption. The importance of not only the boundary layer thickness but also its profile (tanh or linear) is demonstrated. A Briggs-Bers stability analysis is also performed under the assumption of a mass-spring-damper or Helmholtz resonator impedance model.

  5. Surface impedance based microwave imaging method for breast cancer screening: contrast-enhanced scenario.

    PubMed

    Güren, Onan; Çayören, Mehmet; Ergene, Lale Tükenmez; Akduman, Ibrahim

    2014-10-07

    A new microwave imaging method that uses microwave contrast agents is presented for the detection and localization of breast tumours. The method is based on the reconstruction of breast surface impedance through a measured scattered field. The surface impedance modelling allows for representing the electrical properties of the breasts in terms of impedance boundary conditions, which enable us to map the inner structure of the breasts into surface impedance functions. Later a simple quantitative method is proposed to screen breasts against malignant tumours where the detection procedure is based on weighted cross correlations among impedance functions. Numerical results demonstrate that the method is capable of detecting small malignancies and provides reasonable localization.

  6. Acoustics of Jet Surface Interaction-Scrubbing Noise

    NASA Technical Reports Server (NTRS)

    Khavaran, Abbas

    2014-01-01

    Concepts envisioned for the future of civil air transport consist of unconventional propulsion systems in the close proximity of the structure or embedded in the airframe. While such integrated systems are intended to shield noise from community, they also introduce new sources of sound. Sound generation due to interaction of a jet flow past a nearby solid surface is investigated here using the generalized acoustic analogy theory. The analysis applies to the boundary layer noise generated at and near a wall, and excludes the scattered noise component that is produced at the leading or the trailing edge. While compressibility effects are relatively unimportant at very low Mach numbers, frictional heat generation and thermal gradient normal to the surface could play important roles in generation and propagation of sound in high speed jets of practical interest. A general expression is given for the spectral density of the far field sound as governed by the variable density Pridmore-Brown equation. The propagation Greens function is solved numerically for a high aspect-ratio rectangular jet starting with the boundary conditions on the surface and subject to specified mean velocity and temperature profiles between the surface and the observer. It is shown the magnitude of the Greens function decreases with increasing source frequency andor jet temperature. The phase remains constant for a rigid surface, but varies with source location when subject to an impedance type boundary condition. The Greens function in the absence of the surface, and flight effect are also investigated.

  7. Ultrasound-induced lung hemorrhage: Role of acoustic boundary conditions at the pleural surface

    NASA Astrophysics Data System (ADS)

    O'Brien, William D.; Kramer, Jeffrey M.; Waldrop, Tony G.; Frizzell, Leon A.; Miller, Rita J.; Blue, James P.; Zachary, James F.

    2002-02-01

    In a previous study [J. Acoust. Soc. Am. 108, 1290 (2000)] the acoustic impedance difference between intercostal tissue and lung was evaluated as a possible explanation for the enhanced lung damage with increased hydrostatic pressure, but the hydrostatic-pressure-dependent impedance difference alone could not explain the enhanced occurrence of hemorrhage. In that study, it was hypothesized that the animal's breathing pattern might be altered as a function of hydrostatic pressure, which in turn might affect the volume of air inspired and expired. The acoustic impedance difference between intercostal tissue and lung would be affected with altered lung inflation, thus altering the acoustic boundary conditions. In this study, 12 rats were exposed to 3 volumes of lung inflation (inflated: approximately tidal volume; half-deflated: half-tidal volume; deflated: lung volume at functional residual capacity), 6 rats at 8.6-MPa in situ peak rarefactional pressure (MI of 3.1) and 6 rats at 16-MPa in situ peak rarefactional pressure (MI of 5.8). Respiration was chemically inhibited and a ventilator was used to control lung volume and respiratory frequency. Superthreshold ultrasound exposures of the lungs were used (3.1-MHz, 1000-Hz PRF, 1.3-μs pulse duration, 10-s exposure duration) to produce lesions. Deflated lungs were more easily damaged than half-deflated lungs, and half-deflated lungs were more easily damaged than inflated lungs. In fact, there were no lesions observed in inflated lungs in any of the rats. The acoustic impedance difference between intercostal tissue and lung is much less for the deflated lung condition, suggesting that the extent of lung damage is related to the amount of acoustic energy that is propagated across the pleural surface boundary.

  8. Characteristics of Planar Monopole Antenna on High Impedance Electromagnetic Surface

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Jastram, Nathan; Ponchak, George E.; Franklin, Rhonda R.

    2011-01-01

    This paper presents for the first time measured characteristics of a planar monopole antenna placed directly on a high impedance electromagnetic surface or artificial magnetic conductor (AMC). The return loss and radiation patterns are compared between the antenna in free space, and when placed directly on a perfect electrical conductor (PEC), and on the AMC. The antenna measured in free space has a wide pass band from 3 to 10 GHz. The return loss for the antenna on the PEC is nearly all reflected back and the return loss for the antenna on the AMC has a 10 dB bandwidth from 7.5 to 9.5 GHz. The gain of the antenna in free space, on PEC and on AMC is 1, -12 and 10 dBi, respectively. This indicates that the AMC is working properly, sending all the radiation outward with little loss.

  9. Surface acoustic wave microsensors and applications

    NASA Astrophysics Data System (ADS)

    Galipeau, David W.; Story, Patrick R.; Vetelino, Kevin A.; Mileham, R. D.

    1997-06-01

    Surface acoustic wave (SAW) devices have been studied for the last twenty years as highly sensitive yet relatively inexpensive microsensors for applications ranging from gas and biological sensing to thin film and surface characterization. This wide range of applications is due to SAW microsensors high sensitivity to several physical parameters including mass, conductivity, permittivity, stress, temperature and electric fields. Their low cost results from the use of standard batch microelectronic fabrication techniques for their manufacture. In this work several SAW sensing applications are described. These include: gas detection; thin film polymer characterization; dew-point measurements; surface energy measurements; and as a method to measure surface cleanliness. Experimental results are presented along with comparisons to other measurement techniques.

  10. Surface Acoustic Waves to Drive Plant Transpiration

    PubMed Central

    Gomez, Eliot F.; Berggren, Magnus; Simon, Daniel T.

    2017-01-01

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals—as well as the primary vehicle for current e-plant and phtyo-nanotechnology work—we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems. PMID:28361922

  11. Surface Acoustic Waves to Drive Plant Transpiration.

    PubMed

    Gomez, Eliot F; Berggren, Magnus; Simon, Daniel T

    2017-03-31

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals-as well as the primary vehicle for current e-plant and phtyo-nanotechnology work-we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

  12. Design of broadband time-domain impedance boundary conditions using the oscillatory-diffusive representation of acoustical models.

    PubMed

    Monteghetti, Florian; Matignon, Denis; Piot, Estelle; Pascal, Lucas

    2016-09-01

    A methodology to design broadband time-domain impedance boundary conditions (TDIBCs) from the analysis of acoustical models is presented. The derived TDIBCs are recast exclusively as first-order differential equations, well-suited for high-order numerical simulations. Broadband approximations are yielded from an elementary linear least squares optimization that is, for most models, independent of the absorbing material geometry. This methodology relies on a mathematical technique referred to as the oscillatory-diffusive (or poles and cuts) representation, and is applied to a wide range of acoustical models, drawn from duct acoustics and outdoor sound propagation, which covers perforates, semi-infinite ground layers, as well as cavities filled with a porous medium. It is shown that each of these impedance models leads to a different TDIBC. Comparison with existing numerical models, such as multi-pole or extended Helmholtz resonator, provides insights into their suitability. Additionally, the broadly-applicable fractional polynomial impedance models are analyzed using fractional calculus.

  13. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic-impedance measurements. [Patent application

    DOEpatents

    Not Available

    1981-06-10

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material are presented. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material.

  14. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic impedance measurements

    DOEpatents

    Langlois, Gary N.

    1983-09-13

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material.

  15. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic impedance measurements

    DOEpatents

    Langlois, G.N.

    1983-09-13

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material are disclosed. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material. 6 figs.

  16. Surface-Acoustic-Wave Piezoelectric Microbalance

    NASA Technical Reports Server (NTRS)

    Chuan, Raymond L.; Bowers, William D.

    1992-01-01

    Improved piezoelectric microbalances developed for use in measuring masses of volcanic, aerosol, and other small particles suspended in air. Sensitive microbalance used to analyze airborne particles in real time in environments as diverse as clean rooms or upper atmosphere. Surface-acoustic-wave resonator includes input and output sets of interdigitated electrodes and two passive conductive patterns acting as reflectors. Mechanical energy travels both ways out from middle and reflected back toward middle. Microbalance and associated circuitry fit in small package. Circuit draws only 80 mA at 5 V. Sensitivity more than 400 times that of bulk piezoelectric microbalance.

  17. Surface acoustic wave propagation in graphene

    NASA Astrophysics Data System (ADS)

    Thalmeier, Peter; Dóra, Balázs; Ziegler, Klaus

    2010-01-01

    Surface acoustic wave (SAW) propagation is a powerful method to investigate two-dimensional (2D) electron systems. We show how SAW observables are influenced by coupling to the 2D massless Dirac electrons of graphene and argue that Landau oscillations in SAW propagation can be observed as function of gate voltage for constant field. Contrary to other transport measurements, the zero-field SAW propagation gives the wave-vector dependence of graphene conductivity for small wave numbers. We predict a crossover from Schrödinger to Dirac-like behavior as a function of gate voltage, with no attenuation in the latter for clean samples.

  18. Surface Acoustic Wave Atomizer and Electrostatic Deposition

    NASA Astrophysics Data System (ADS)

    Yamagata, Yutaka

    A new methodology for fabricating thin film or micro patters of organic/bio material using surface acoustic wave (SAW) atomizer and electrostatic deposition is proposed and characteristics of atomization techniques are discussed in terms of drop size and atomization speed. Various types of SAW atomizer are compared with electrospray and conventional ultrasonic atomizers. It has been proved that SAW atomizers generate drops as small as electrospray and have very fast atomization speed. This technique is applied to fabrication of micro patterns of proteins. According to the result of immunoassay, the specific activity of immunoglobulin was preserved after deposition process.

  19. Surface acoustic wave atomizer and electrostatic deposition.

    PubMed

    Yamagata, Yutaka

    2010-01-01

    A new methodology for fabricating thin film or micro patters of organic/bio material using surface acoustic wave (SAW) atomizer and electrostatic deposition is proposed and characteristics of atomization techniques are discussed in terms of drop size and atomization speed. Various types of SAW atomizer are compared with electrospray and conventional ultrasonic atomizers. It has been proved that SAW atomizers generate drops as small as electrospray and have very fast atomization speed. This technique is applied to fabrication of micro patterns of proteins. According to the result of immunoassay, the specific activity of immunoglobulin was preserved after deposition process.

  20. Stability analysis and design of time-domain acoustic impedance boundary conditions for lined duct with mean flow.

    PubMed

    Liu, Xin; Huang, Xun; Zhang, Xin

    2014-11-01

    This work develops the so-called compensated impedance boundary conditions that enable stable time domain simulations of sound propagation in a lined duct with uniform mean flow, which has important practical interest for noise emission by aero-engines. The proposed method is developed analytically from an unusual perspective of control that shows impedance boundary conditions act as closed-loop feedbacks to an overall duct acoustic system. It turns out that those numerical instabilities of time domain simulations are caused by deficient phase margins of the corresponding control-oriented model. A particular instability of very low frequencies in the presence of steady uniform background mean flow, in addition to the well known high frequency numerical instabilities at the grid size, can be identified using this analysis approach. Stable time domain impedance boundary conditions can be formulated by including appropriate phaselead compensators to achieve desired phase margins. The compensated impedance boundary conditions can be simply designed with no empirical parameter, straightforwardly integrated with ordinary linear acoustic models, and efficiently calculated with no need of resolving sheared boundary layers. The proposed boundary conditions are validated by comparing against asymptotic solutions of spinning modal sound propagation in a duct with a hard-soft interface and reasonable agreement is achieved.

  1. Surface acoustic wave microsensors and applications

    NASA Astrophysics Data System (ADS)

    Galipeau, David W.; Story, Patrick R.; Vetelino, Kevin A.; Mileham, Russell D.

    1997-12-01

    Surface acoustic wave (SAW) devices have been studied for the last twenty years as highly sensitive yet relatively inexpensive microsensors for applications ranging from temperature and stress to gas and biological sensing. This wide range of applications is due to the SAW microsensors' high sensitivity to several physical parameters including mass, temperature, stress, and conductivity. Their low cost results from the use of standard batch microelectronic fabrication techniques for their manufacture. In this paper several chemical sensing applications for SAW devices are described. These include: gas detection; thin-film polymer characterization; dew-point measurements; surface energy measurements; and as a method to measure surface cleanliness. Experimental results are presented along with comparisons to other measurement techniques.

  2. Surface acoustic load sensing using a face-shear PIN-PMN-PT single-crystal resonator.

    PubMed

    Kim, Kyungrim; Zhang, Shujun; Jiang, Xiaoning

    2012-11-01

    Pb(In(0.5)Nb(0.5))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) resonators for surface acoustic load sensing are presented in this paper. Different acoustic loads are applied to thickness mode, thickness-shear mode, and face-shear mode resonators, and the electrical impedances at resonance and anti-resonance frequencies are recorded. More than one order of magnitude higher sensitivity (ratio of electrical impedance change to surface acoustic impedance change) at the resonance is achieved for the face-shear-mode resonator compared with other resonators with the same dimensions. The Krimholtz, Leedom, and Matthaei (KLM) model is used to verify the surface acoustic loading effect on the electrical impedance spectrum of face-shear PIN-PMN-PT single-crystal resonators. The demonstrated high sensitivity of face-shear mode resonators to surface loads is promising for a broad range of applications, including artificial skin, biological and chemical sensors, touch screens, and other touch-based sensors.

  3. On the Acoustic Absorption of Porous Materials with Different Surface Shapes and Perforated Plates

    NASA Astrophysics Data System (ADS)

    CHEN, WEN-HWA; LEE, FAN-CHING; CHIANG, DAR-MING

    2000-10-01

    In architectural acoustic design, perforated plates are often used to protect porous materials from erosion. Although porous materials are usually applied to passive noise control, the effects of their surface shapes are seldom studied. To study the acoustic absorption of porous materials with different surface shapes and perforated plates, an efficient finite element procedure, which is derived by the Galerkin residual method and Helmholtz wave propagation equation, is used in this work. The two-microphone transfer function method and the modified Ingard and Dear impedance tube testing system are employed to measure the parameters deemed necessary for the finite element analysis, such as complex wave propagation constant, characteristic impedance and flow resistivity. For verifying the finite element results, the two-microphone transfer function method is also applied to measure the absorption coefficients of the discussed acoustic absorbers. Four surface shapes of commercially available porous materials, i.e., triangle, semicircle, convex rectangle and plate shapes, are chosen for analysis. The porosity of perforated plates is then evaluated. Finally, the distinct effect of the flow resistivity of porous materials on the acoustic absorption is demonstrated.

  4. Scattering of surface plasmon polaritons by impedance barriers: Dependence on angle of incidence

    NASA Astrophysics Data System (ADS)

    Nikitin, A. Yu.; Brucoli, G.; García-Vidal, F. J.; Martín-Moreno, L.

    2008-05-01

    This paper studies theoretically surface plasmon polariton scattering by one-dimensional defects of metal surface impedance at oblique incidence. Surface impedance boundary conditions are used to formulate an integral equation which can be solved both analytically and numerically to yield the transmission, reflection, and out-of-plane cross section as a function of angle of incidence and other parameters. Numerical calculations, as well as analytical expressions, obtained within the Born approximation are presented. Green’s tensor approach is also applied so as to expand such analysis to region in which the surface impedance boundary conditions are not appropriate. We show that the angular dependencies for surface plasmon polariton scattering by impedance defects and by surface relief defects are essentially different. The angular dependency of surface plasmon polariton scattering by an impedance defect features an analog to Brewster’s angle that is explained in terms of dipole polarization of the defect.

  5. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    PubMed

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  6. Upper surface blowing aerodynamic and acoustic characteristics

    NASA Technical Reports Server (NTRS)

    Ryle, D. M., Jr.; Braden, J. A.; Gibson, J. S.

    1977-01-01

    Aerodynamic performance at cruise, and noise effects due to variations in nacelle and wing geometry and mode of operation are studied using small aircraft models that simulate upper surface blowing (USB). At cruise speeds ranging from Mach .50 to Mach .82, the key determinants of drag/thrust penalties are found to be nozzle aspect ratio, boattailing angle, and chordwise position; number of nacelles; and streamlined versus symmetric configuration. Recommendations are made for obtaining favorable cruise configurations. The acoustic studies, which concentrate on the noise created by the jet exhaust flow and its interaction with wing and flap surfaces, isolate several important sources of USB noise, including nozzle shape, exit velocity, and impingement angle; flow pathlength; and flap angle and radius of curvature. Suggestions for lessening noise due to trailing edge flow velocity, flow pathlength, and flow spreading are given, though compromises between some design options may be necessary.

  7. A direct method for measuring acoustic ground impedance in long-range propagation experiments.

    PubMed

    Soh, Jin H; Gilbert, Kenneth E; Frazier, W M Garth; Talmadge, Carrick L; Waxler, Roger

    2010-11-01

    A method is reported for determining ground impedance in long-range propagation experiments by using the definition of impedance directly. The method is envisioned as way of measuring the impedence at multiple locations along the propagation path, using the signals broadcast during the experiment itself. In a short-range (10 m) test, the direct method was in good agreement with a more conventional model-based least-squares method. The utility of the direct method was demonstrated in a 400 m propagation experiment in a agricultural field. The resulting impedance was consistent with the impedance measured previously in the same field.

  8. Effects of optimized and sub-optimum two degree of freedom lining tolerances on modeled inlet acoustic attenuation and Normal incidence impedance measurement at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Burd, David R.

    This work first investigates the effect of manufacturing tolerances on realized attenuation for two degree-of-freedom linings with the use of lining models and finite element duct propagation codes. Acoustic linings were created for two turbofan engines that optimize attenuation at takeoff/sideline and approach conditions. Lining physical and geometric parameters were set, which best meet the optimum impedance requirements at two target frequencies. Similar linings were created to investigate sub-optimum designs. Variations of these parameters representing realistic manufacturing tolerances were used to systematically examine the effect on installed impedance and predicted attenuation. Attenuation at sideline and approach conditions was found to be sensitive to manufacturing tolerances around optimum conditions. The results of the study are case dependent; however the analysis scheme presented provides a method for cost-benefit analysis of manufacturing processes. In a second study, an impedance tube, with an associated data analysis method, was developed and analyzed for temperature uncertainties that allowed the measurement of impedance of acoustic samples at elevated temperatures. This impedance measurement method was validated at room temperature by comparing the results with predicted impedance from empirically based impedance models and with impedance measurements in a standard traversing microphone impedance tube. Impedance for four samples was measured at elevated temperatures, and the results were compared to room temperature measurements. For two of the samples, the impedances measured at elevated temperatures were compared to the results of extensions of room temperature empirical models, confirming the trend of the results of the elevated temperature measurements.

  9. Determination of acoustic impedances of multi matching layers for narrowband ultrasonic airborne transducers at frequencies <2.5 MHz - Application of a genetic algorithm.

    PubMed

    Saffar, Saber; Abdullah, Amir

    2012-01-01

    The effective ultrasonic energy radiation into the air of piezoelectric transducers requires using multilayer matching systems with accurately selected acoustic impedances and the thickness of particular layers. One major problem of ultrasonic transducers, radiating acoustic energy into air, is to find the proper acoustic impedances of one or more matching layers. This work aims at developing an original solution to the acoustic impedance mismatch between transducer and air. If the acoustic impedance defences between transducer and air be more, then finding best matching layer(s) is harder. Therefore we consider PZT (lead zirconate titanate piezo electric) transducer and air that has huge acoustic impedance deference. The vibration source energy (PZT), which is used to generate the incident wave, consumes a part of the mechanical energy and converts it to an electrical one in theoretical calculation. After calculating matching layers, we consider the energy source as layer to design a transducer. However, this part of the mechanical energy will be neglected during the mathematical work. This approximation is correct only if the transducer is open-circuit. Since the possibilities of choosing material with required acoustic impedance are limited (the counted values cannot always be realized and applied in practice) it is necessary to correct the differences between theoretical values and the possibilities of practical application of given acoustic impedances. Such a correction can be done by manipulating other parameters of matching layers (e.g. by changing their thickness). The efficiency of the energy transmission from the piezoceramic transducer through different layers with different thickness and different attenuation enabling a compensation of non-ideal real values by changing their thickness was computer analyzed (base on genetic algorithm). Firstly, three theoretical solutions were investigated. Namely, Chebyshev, Desilets and Souquet theories. However, the

  10. Nozzleless Spray Cooling Using Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Ang, Kar Man; Yeo, Leslie; Friend, James; Hung, Yew Mun; Tan, Ming Kwang

    2015-11-01

    Due to its reliability and portability, surface acoustic wave (SAW) atomization is an attractive approach for the generation of monodispersed microdroplets in microfluidics devices. Here, we present a nozzleless spray cooling technique via SAW atomization with key advantage of downward scalability by simply increasing the excitation frequency. With generation of micron size droplets through surface destabilization using SAW, the clogging issues commonly encountered by spraying nozzle can be neutralized. Using deionised water, cooling is improved when the atomization rate is increased and the position of the device is optimized such that the atomized droplets can be easily seeded into the upstream of the flow circulation. Cooling is further improved with the use of nanofluids; a suspension of nanoparticles in water. By increasing nanoparticle mass concentration from 1% to 3%, cooling is enhanced due to the deposition and formation of nanoparticle clusters on heated surface and eventually increase the surface area. However, further increase the concentration to 10% reduces the cooling efficiency due to drastic increase in viscosity μ that leads to lower atomization rate which scales as ṁ ~μ - 1 / 2 .

  11. Simultaneous backward data transmission and power harvesting in an ultrasonic transcutaneous energy transfer link employing acoustically dependent electric impedance modulation.

    PubMed

    Ozeri, Shaul; Shmilovitz, Doron

    2014-09-01

    The advancement and miniaturization of body implanted medical devices pose several challenges to Ultrasonic Transcutaneous Energy Transfer (UTET), such as the need to reduce the size of the piezoelectric resonator, and the need to maximize the UTET link power-transfer efficiency. Accordingly, the same piezoelectric resonator that is used for energy harvesting at the body implant, may also be used for ultrasonic backward data transfer, for instance, through impedance modulation. This paper presents physical considerations and design guidelines of the body implanted transducer of a UTET link with impedance modulation for a backward data transfer. The acoustic matching design procedure was based on the 2×2 transfer matrix chain analysis, in addition to the Krimholtz Leedom and Matthaei KLM transmission line model. The UTET power transfer was carried out at a frequency of 765 kHz, continuous wave (CW) mode. The backward data transfer was attained by inserting a 9% load resistance variation around its matched value (550 Ohm), resulting in a 12% increase in the acoustic reflection coefficient. A backward data transmission rate of 1200 bits/s was experimentally demonstrated using amplitude shift keying, simultaneously with an acoustic power transfer of 20 mW to the implant.

  12. Standing surface acoustic wave based cell coculture.

    PubMed

    Li, Sixing; Guo, Feng; Chen, Yuchao; Ding, Xiaoyun; Li, Peng; Wang, Lin; Cameron, Craig E; Huang, Tony Jun

    2014-10-07

    Precise reconstruction of heterotypic cell-cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell-cell interactions.

  13. Standing Surface Acoustic Wave Based Cell Coculture

    PubMed Central

    2015-01-01

    Precise reconstruction of heterotypic cell–cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell–cell interactions. PMID:25232648

  14. Acceleration of solitary ion-acoustic surface waves

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1991-10-01

    We consider the interaction between long-wavelength ion-acoustic and electron-plasma surface waves on a semi-infinite plasma. It then turns out that an ion-acoustic solitary wave can be accelerated when the amplitude of the electron-plasma surface wave varies in time.

  15. Improved multimodal method for the acoustic propagation in waveguides with a wall impedance and a uniform flow

    NASA Astrophysics Data System (ADS)

    Mercier, Jean-François; Maurel, Agnès

    2016-06-01

    We present an efficient multimodal method to describe the acoustic propagation in the presence of a uniform flow in a waveguide with locally a wall impedance treatment. The method relies on a variational formulation of the problem, which allows to derive a multimodal formulation within a rigorous mathematical framework, notably to properly account for the boundary conditions on the walls (being locally the Myers condition and the Neumann condition otherwise). Also, the method uses an enriched basis with respect to the usual cosine basis, able to absorb the less converging part of the modal series and thus, to improve the convergence of the method. Using the cosine basis, the modal method has a low convergence, 1/N, with N the order of truncation. Using the enriched basis, the improvement in the convergence is shown to depend on the Mach number, from 1/N5 to roughly 1/N1.5 for M=0 to M close to unity. The case of a continuously varying wall impedance is considered, and we discuss the limiting case of piecewise constant impedance, which defines pressure edge conditions at the impedance discontinuities.

  16. Quantitative non-linear ultrasonic imaging of targets with significant acoustic impedance contrast--an experimental study.

    PubMed

    Guillermin, Régine; Lasaygues, Philippe; Rabau, Guy; Lefebvre, Jean-Pierre

    2013-08-01

    This study deals with the reconstruction, from ultrasonic measured data, of the sound speed profile of a penetrable two-dimensional target of arbitrary cross-section embedded in an infinite medium. Green's theorem is used to obtain a domain integral representation of the acoustical scattered field, and a discrete formulation of the inverse problem is obtained using a moment method. An iterative non-linear algorithm minimizing the discrepancy between the measured and computed scattered fields is used to reconstruct the sound speed profile in the region of interest. The minimization process is performed using a conjugated-gradient method. An experimental study with significant acoustical impedance contrast targets immersed in water was performed. Images of the sound speed profile obtained by inversion of experimental data are presented.

  17. Acoustic Tomography of the Atmospheric Surface Layer

    DTIC Science & Technology

    2014-11-28

    resolution of an ultrasonic anemometer , it was suggested that one consider it is as a small acoustic tomography array and apply appropriate inverse...Fairall, D. Keith Wilson, Ludovic Bariteau. Sonic Anemometer as a Small Acoustic Tomography Array, Boundary-Layer Meteorology, (08 2013): 0. doi...Received Paper 3.00 S. N. Vecherin, V. E. Ostashev, D. K. Wilson, A. Grached. Utilization of an acoustic tomography array as a large sonic anemometer

  18. Nanoliter-droplet acoustic streaming via ultra high frequency surface acoustic waves.

    PubMed

    Shilton, Richie J; Travagliati, Marco; Beltram, Fabio; Cecchini, Marco

    2014-08-06

    The relevant length scales in sub-nanometer amplitude surface acoustic wave-driven acoustic streaming are demonstrated. We demonstrate the absence of any physical limitations preventing the downscaling of SAW-driven internal streaming to nanoliter microreactors and beyond by extending SAW microfluidics up to operating frequencies in the GHz range. This method is applied to nanoliter scale fluid mixing.

  19. Surface acoustic wave (SAW) vibration sensors.

    PubMed

    Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

    2011-01-01

    In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  20. Acoustic environment of the Martian surface

    NASA Astrophysics Data System (ADS)

    Williams, Jean-Pierre

    2001-03-01

    Prompted by the Mars Microphone aboard the 1998 Mars Polar Lander, a theoretical study of the acoustical environment of the Martian surface has been made to ascertain how the propagation of sound is attenuated under such conditions and to predict what sounds may be detectable by a microphone. Viscous and thermal relaxation (termed classical absorption), molecular relaxation, and geometric attenuation are considered. Classical absorption is stronger under Martian conditions resulting in sounds in the audible frequencies (20 Hz to 20 kHz) being more strongly attenuated than in the terrestrial environment. The higher frequencies (>3000 Hz) will be severely attenuated as the absorption is frequency dependent. At very low infrasound frequencies (i.e., <10 Hz), attenuation will be mostly due to geometric spreading of the propagating wave front and will therefore be more similar to the terrestrial surface environment. Probable sound sources in the landed environment include wind-blown dust and sand from large dust storms, dust devils, and possible associated electrostatic discharge. The sounds most likely to be detected will be sounds generated by the lander itself and aeroacoustic noises generated by winds blowing against the lander and its instruments.

  1. Surface acoustic wave biosensors: a review.

    PubMed

    Länge, Kerstin; Rapp, Bastian E; Rapp, Michael

    2008-07-01

    This review presents an overview of 20 years of worldwide development in the field of biosensors based on special types of surface acoustic wave (SAW) devices that permit the highly sensitive detection of biorelevant molecules in liquid media (such as water or aqueous buffer solutions). 1987 saw the first approaches, which used either horizontally polarized shear waves (HPSW) in a delay line configuration on lithium tantalate (LiTaO(3)) substrates or SAW resonator structures on quartz or LiTaO(3) with periodic mass gratings. The latter are termed "surface transverse waves" (STW), and they have comparatively low attenuation values when operated in liquids. Later Love wave devices were developed, which used a film resonance effect to significantly reduce attenuation. All of these sensor approaches were accompanied by the development of appropriate sensing films. First attempts used simple layers of adsorbed antibodies. Later approaches used various types of covalently bound layers, for example those utilizing intermediate hydrogel layers. Recent approaches involve SAW biosensor devices inserted into compact systems with integrated fluidics for sample handling. To achieve this, the SAW biosensors can be embedded into micromachined polymer housings. Combining these two features will extend the system to create versatile biosensor arrays for generic lab use or for diagnostic purposes.

  2. Wideband finite difference time domain implementation of surface impedance boundary conditions for good conductors

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.; Yee, Kane S.

    1991-01-01

    Surface impedance boundary conditions are used to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be used to avoid using small cells, made necessary by shorter wavelengths in conducting media, throughout the solution volume. A one dimensional implementation is presented for a surface impedance boundary condition for good conductors in the Finite Difference Time Domain (FDTD) technique. In order to illustrate the FDTD surface impedance boundary condition, a planar air-lossy dielectric interface is considered.

  3. Droplet actuation by surface acoustic waves: an interplay between acoustic streaming and radiation pressure

    NASA Astrophysics Data System (ADS)

    Brunet, Philippe; Baudoin, Michael; Matar, Olivier Bou; Zoueshtiagh, Farzam

    2010-11-01

    Surface acoustic waves (SAW) are known to be a versatile technique for the actuation of sessile drops. Droplet displacement, internal mixing or drop splitting, are amongst the elementary operations that SAW can achieve, which are useful on lab-on-chip microfluidics benches. On the purpose to understand the underlying physical mechanisms involved during these operations, we study experimentally the droplet dynamics varying different physical parameters. Here in particular, the influence of liquid viscosity and acoustic frequency is investigated: it is indeed predicted that both quantities should play a role in the acoustic-hydrodynamic coupling involved in the dynamics. The key point is to compare the relative magnitude of the attenuation length, i.e. the scale within which the acoustic wave decays in the fluid, and the size of the drop. This relative magnitude governs the relative importance of acoustic streaming and acoustic radiation pressure, which are both involved in the droplet dynamics.

  4. Ultrafast microfluidics using surface acoustic waves

    PubMed Central

    Yeo, Leslie Y.; Friend, James R.

    2009-01-01

    We demonstrate that surface acoustic waves (SAWs), nanometer amplitude Rayleigh waves driven at megahertz order frequencies propagating on the surface of a piezoelectric substrate, offer a powerful method for driving a host of extremely fast microfluidic actuation and micro∕bioparticle manipulation schemes. We show that sessile drops can be translated rapidly on planar substrates or fluid can be pumped through microchannels at 1–10 cm∕s velocities, which are typically one to two orders quicker than that afforded by current microfluidic technologies. Through symmetry-breaking, azimuthal recirculation can be induced within the drop to drive strong inertial microcentrifugation for micromixing and particle concentration or separation. Similar micromixing strategies can be induced in the same microchannel in which fluid is pumped with the SAW by merely changing the SAW frequency to rapidly switch the uniform through-flow into a chaotic oscillatory flow by exploiting superpositioning of the irradiated sound waves from the sidewalls of the microchannel. If the flow is sufficiently quiescent, the nodes of the transverse standing wave that arises across the microchannel also allow for particle aggregation, and hence, sorting on nodal lines. In addition, the SAW also facilitates other microfluidic capabilities. For example, capillary waves excited at the free surface of a sessile drop by the SAW underneath it can be exploited for micro∕nanoparticle collection and sorting at nodal points or lines at low powers. At higher powers, the large accelerations off the substrate surface as the SAW propagates across drives rapid destabilization of the drop free surface giving rise to inertial liquid jets that persist over 1–2 cm in length or atomization of the entire drop to produce 1–10 μm monodispersed aerosol droplets, which can be exploited for ink-jet printing, mass spectrometry interfacing, or pulmonary drug delivery. The atomization of polymer∕protein solutions

  5. Use of neural networks for prediction of lateral reservoir porosity from seismic acoustic impedance: A case study from Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Alamoudi, Waleed Ahmad

    Reservoir porosity controls the strategies for reservoir management. Porosity is the primary key to a reliable reservoir model. The most economic method of evaluating reservoir porosity on a foot-by-foot basis is from core and well log data analysis. Lateral reservoir porosity is estimated using geostatistical method from well log data or from the integration of well log data and seismic data. However, the petroleum industry needs more accurate, reliable methods to estimate porosity from seismic data. Neural network analysis is one of the latest technologies available to the petroleum industry. In this study, I report results of an investigation of the use of neural network to predict lateral reservoir porosity. The approach is based on using average seismic acoustic impedances extracted from a 3D seismic volume to predict lateral average porosity for 13 reservoir geological layers. A neural network was trained using different subsets of well log data from 9 hydrocarbon wells and validated using the reminder of the wells. Data from the Unayzah reservoir in CNR field located in central basin of Saudi Arabia was used in this study. Model-based post-stack seismic inversion was used to produce a seismic acoustic impedance volume. Average impedance maps were then created for 13 layers from the Unayzah reservoir interval in the CNR field. Back-propagation neural network technique successfully estimated lateral reservoir porosity from seismic acoustic impedance and density attributes. The neural network performance using data from 6 wells (C, D, F, G, I, J), more or less distributed along the field axis, provided a better correlation and less scatter than other well training geometries in the testing phase. The A, B, and H wells were used for validation. Goodness of fit was 0.9985. The good neural network prediction in the testing phase reflects the neural network capability to estimate average reservoir porosities. Predicted lateral porosity maps incorporate

  6. Surface acoustic wave devices for sensor applications

    NASA Astrophysics Data System (ADS)

    Bo, Liu; Xiao, Chen; Hualin, Cai; Mohammad, Mohammad Ali; Xiangguang, Tian; Luqi, Tao; Yi, Yang; Tianling, Ren

    2016-02-01

    Surface acoustic wave (SAW) devices have been widely used in different fields and will continue to be of great importance in the foreseeable future. These devices are compact, cost efficient, easy to fabricate, and have a high performance, among other advantages. SAW devices can work as filters, signal processing units, sensors and actuators. They can even work without batteries and operate under harsh environments. In this review, the operating principles of SAW sensors, including temperature sensors, pressure sensors, humidity sensors and biosensors, will be discussed. Several examples and related issues will be presented. Technological trends and future developments will also be discussed. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and the China Postdoctoral Science Foundation (CPSF).

  7. Surface-acoustic-wave (SAW) flow sensor

    NASA Astrophysics Data System (ADS)

    Joshi, Shrinivas G.

    1991-03-01

    The use of a surface-acoustic-wave (SAW) device to measure the rate of gas flow is described. A SAW oscillator heated to a suitable temperature above ambient is placed in the path of a flowing gas. Convective cooling caused by the gas flow results in a change in the oscillator frequency. A 73-MHz oscillator fabricated on 128 deg rotated Y-cut lithium niobate substrate and heated to 55 C above ambient shows a frequency variation greater than 142 kHz for flow-rate variation from 0 to 1000 cu cm/min. The output of the sensor can be calibrated to provide a measurement of volume flow rate, pressure differential across channel ports, or mass flow rate. High sensitivity, wide dynamic range, and direct digital output are among the attractive features of this sensor. Theoretical expressions for the sensitivity and response time of the sensor are derived. It is shown that by using ultrasonic Lamb waves propagating in thin membranes, a flow sensor with faster response than a SAW sensor can be realized.

  8. Reduced-volume antennas with integrated high-impedance electromagnetic surfaces.

    SciTech Connect

    Forman, Michael A.

    2006-11-01

    Several antennas with integrated high-impedance surfaces are presented. The high-impedance surface is implemented as a composite right/left-handed (CRLH) metamaterial fabricated from a periodic structure characterized by a substrate, filled with an array of vertical vias and capped by capacitive patches. Omnidirectional antennas placed in close proximity to the high-impedance surface radiate hemispherically with an increase in boresight far-field pattern gain of up to 10 dB and a front-to-back ratio as high as 13 dB at 2.45 GHz. Several TEM rectangular horn antennas are realized by replacing conductor walls with high-impedance surfaces. The TEM horn antennas are capable of operating below the TE{sub 1,0} cutoff frequency of a standard all-metal horn antenna, enabling a reduction in antenna volume. Above the cutoff frequency the TEM horn antennas function similarly to standard rectangular horn antennas.

  9. Wideband finite difference time domain implementation of surface impedance boundary conditions for good conductors

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.; Yee, Kane S.

    1991-01-01

    Surface impedance boundary conditions are employed to reduce the solution volume during the analysis of scattering from lossy dielectric objects. In a finite difference solution, they also can be utilized to avoid using small cells, made necessary by shorter wavelengths in conducting media, throughout the solution volume. A 1-D implementation for a surface impedance boundary condition for good conductors in the Finite Difference Time Domain (FDTD) technique.

  10. A PARAMETRIC STUDY OF BCS RF SURFACE IMPEDANCE WITH MAGNETIC FIELD USING THE XIAO CODE

    SciTech Connect

    Reece, Charles E.; Xiao, Binping

    2013-09-01

    A recent new analysis of field-dependent BCS rf surface impedance based on moving Cooper pairs has been presented.[1] Using this analysis coded in Mathematica TM, survey calculations have been completed which examine the sensitivities of this surface impedance to variation of the BCS material parameters and temperature. The results present a refined description of the "best theoretical" performance available to potential applications with corresponding materials.

  11. Thin Superconducting Film Characterization by Surface Acoustic Waves.

    DTIC Science & Technology

    2014-09-26

    NUMBER 2. GOVT ACCESSION NO. 3 RECIPIENT’S CA ALOG NUMBER ~~AFOSR TR -0 8 4. TITLE (and Subtitle) 5 TYPE OF REPORT & PERIOD COVERED Thin Superconducting ...thin film superconductor surface acoustic waves I SAW electron phonon interaction superconducting energy gap electron mean free path vortex...electrical resistivity and the attenuation of surface ,e J -acoustic waves (SAW) were measured in the superconducting state of a L granular lead film

  12. Estimating propagation velocity through a surface acoustic wave sensor

    DOEpatents

    Xu, Wenyuan; Huizinga, John S.

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  13. Flow Duct Data for Validation of Acoustic Liner Codes for Impedance Eduction

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Munro, Scott; Gaeta, R. J., Jr.

    2000-01-01

    The objective of the study reported here was to acquire acoustic and flow data with hard and lined duct wall duct sections for validation of a liner prediction code being developed at NASA LaRC. Both the mean flowfield and acoustic flowfields were determined in a cross-plane of the rectangular duct. A flow duct facility with acoustic drivers connected to a rectangular (4.7 x 2.0 inch) source section and a linear acoustic liner mounted downstream of the source section was used in this study. The liner section was designed to allow liner materials to be placed on all 4 walls of the duct. The test liner was of the locally-reacting type and was made from a ceramic material. The material, consisting of a tubular structure, was provided by NASA LaRC. The liner was approximately 8.89 cm (3.5 inches) thick. For the current study, only the two "short" sides of the duct were lined with liner material. The other two sides were hard walls. Two especially built instrumentation sections were attached on either sides of the liner section to allow acoustic and flow measurements to be made upstream and downstream of the liner. The two instrumentation duct sections were built to allow measurement of acoustic and flow properties at planes perpendicular to flow upstream and downstream of the liner section. The instrumentation section was also designed to provide a streamwise gradient in acoustic (complex) pressure from which the acoustic particle velocity, needed for the model validation, can be computed. Flow measurements included pressure, temperature, and velocity profiles upstream of the liner section. The in-flow sound pressure levels and phases were obtained with a microphone probe equipped with a nose cone in two cross planes upstream of the liner and two cross plane downstream of the liner. In addition to the acoustic measurements at the cross planes. axial centerline acoustic data was acquired using an axially traversing microphone probe which was traversed from a location

  14. 3-D Acoustic Scattering from 2-D Rough Surfaces Using A Parabolic Equation Model

    DTIC Science & Technology

    2013-12-01

    acoustic propagation signals, especially at mid- frequencies and higher (e.g., acoustic communications systems). For many years, the effects of rough...of the effect of surface scattering on 3-D propagation , which is critical in evaluating the variability in underwater acoustic propagation . Results...14. SUBJECT TERMS Acoustic Propagation , Acoustic Scattering, Sea Surface Perturbations, Split- Step Fourier Algorithm, Finite Difference Algorithm

  15. Estimation of Surface Waves along a Metal Grating Using an Equivalent Impedance Model

    NASA Astrophysics Data System (ADS)

    Shimoda, Michinari; Matsuda, Toyonori; Matsuo, Kazunori; Iyama, Yoshitada

    The cause-and-effect relation between plasmon-resonance absorption and surface wave in a sinusoidal metal grating is investigated. By introducing an equivalent impedance model, similar to an equivalent circuit on an electric circuit, which is an impedance boundary value problem on the fictitious surface over the grating, we estimate the surface wave from the eigen field of the model by using the resonance property of the scattered field. Through numerical examples, we illustrate that the absorption in the grating occurs in the condition of exciting the surface wave along the model, and the real part of the surface impedance is negative on about half part of the fictitious surface in the condition.

  16. Acoustic carrier transportation induced by surface acoustic waves in graphene in solution

    NASA Astrophysics Data System (ADS)

    Okuda, Satoshi; Ikuta, Takashi; Kanai, Yasushi; Ono, Takao; Ogawa, Shinpei; Fujisawa, Daisuke; Shimatani, Masaaki; Inoue, Koichi; Maehashi, Kenzo; Matsumoto, Kazuhiko

    2016-04-01

    The acoustic charge transportation induced by surface acoustic wave (SAW) propagation in graphene in solution was investigated. The sign of acoustic current (I A) was found to switch when crossing the Dirac point because the major carrier was transitioned from holes to electrons by the change in electrolyte-gate voltage. I A also exhibited a peak value under conditions of both hole and electron conduction. These results can be explained on the basis of a change in the type of major carrier in graphene, as well as a change in the carrier mobility of graphene.

  17. Anisotropic Swirling Surface Acoustic Waves from Inverse Filtering for On-Chip Generation of Acoustic Vortices

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Thomas, Jean-Louis; Charron, Eric; Bussonnière, Adrien; Bou Matar, Olivier; Baudoin, Michael

    2015-09-01

    From radio-electronics signal analysis to biological sample actuation, surface acoustic waves (SAWs) are involved in a multitude of modern devices. However, only the most simple standing or progressive waves such as plane and focused waves have been explored so far. In this paper, we expand the SAW toolbox with a wave family named "swirling surface acoustic waves" which are the 2D anisotropic analogue of bulk acoustic vortices. Similarly to their 3D counterpart, they appear as concentric structures of bright rings with a phase singularity in their center resulting in a central dark spot. After the rigorous mathematical definition of these waves, we synthesize them experimentally through the inverse filtering technique revisited for surface waves. For this purpose, we design a setup combining arrays of interdigitated transducers and a multichannel electronic that enables one to synthesize any prescribed wave field compatible with the anisotropy of the substrate in a region called the "acoustic scene." This work opens prospects for the design of integrated acoustic vortex generators for on-chip selective acoustic tweezing.

  18. Self-focusing of electromagnetic surface waves on a nonlinear impedance surface

    SciTech Connect

    Luo, Zhangjie; Chen, Xing; Long, Jiang; Quarfoth, Ryan; Sievenpiper, Daniel

    2015-05-25

    The self-focusing effect of optical beams has been a popular topic of study for quite a while, but such a nonlinear phenomenon at microwave frequencies has never been realized, partially due to the underdevelopment of nonlinear material. In this research, self-focused electromagnetic (EM) surface waves are demonstrated on a circuit-based, power-dependent impedance surface. The formation of a self-focused beam is investigated using a series of discrete-time simulations, and the result is further validated in measurement. It is experimentally observed that, in contrast to the normal scattering of low-power surface waves, high-power waves propagate through the surface while maintaining narrow beam width, and even converge extremely tightly to create a hot spot with higher power. The result is essentially a nonlinear effect of the surface that compensates for the natural tendency of surface waves to diffract. This intriguing experiment can be extended to various potential EM applications such as power-dependent beam steering antennas and nonlinear microwave propagation or dissipation.

  19. Acoustic tweezers via sub–time-of-flight regime surface acoustic waves

    PubMed Central

    Collins, David J.; Devendran, Citsabehsan; Ma, Zhichao; Ng, Jia Wei; Neild, Adrian; Ai, Ye

    2016-01-01

    Micrometer-scale acoustic waves are highly useful for refined optomechanical and acoustofluidic manipulation, where these fields are spatially localized along the transducer aperture but not along the acoustic propagation direction. In the case of acoustic tweezers, such a conventional acoustic standing wave results in particle and cell patterning across the entire width of a microfluidic channel, preventing selective trapping. We demonstrate the use of nanosecond-scale pulsed surface acoustic waves (SAWs) with a pulse period that is less than the time of flight between opposing transducers to generate localized time-averaged patterning regions while using conventional electrode structures. These nodal positions can be readily and arbitrarily positioned in two dimensions and within the patterning region itself through the imposition of pulse delays, frequency modulation, and phase shifts. This straightforward concept adds new spatial dimensions to which acoustic fields can be localized in SAW applications in a manner analogous to optical tweezers, including spatially selective acoustic tweezers and optical waveguides. PMID:27453940

  20. Scatterer size and concentration estimation technique based on a 3D acoustic impedance map from histologic sections

    NASA Astrophysics Data System (ADS)

    Mamou, Jonathan; Oelze, Michael L.; O'Brien, William D.; Zachary, James F.

    2004-05-01

    Accurate estimates of scatterer parameters (size and acoustic concentration) are beneficial adjuncts to characterize disease from ultrasonic backscatterer measurements. An estimation technique was developed to obtain parameter estimates from the Fourier transform of the spatial autocorrelation function (SAF). A 3D impedance map (3DZM) is used to obtain the SAF of tissue. 3DZMs are obtained by aligning digitized light microscope images from histologic preparations of tissue. Estimates were obtained for simulated 3DZMs containing spherical scatterers randomly located: relative errors were less than 3%. Estimates were also obtained from a rat fibroadenoma and a 4T1 mouse mammary tumor (MMT). Tissues were fixed (10% neutral-buffered formalin), embedded in paraffin, serially sectioned and stained with H&E. 3DZM results were compared to estimates obtained independently against ultrasonic backscatter measurements. For the fibroadenoma and MMT, average scatterer diameters were 91 and 31.5 μm, respectively. Ultrasonic measurements yielded average scatterer diameters of 105 and 30 μm, respectively. The 3DZM estimation scheme showed results similar to those obtained by the independent ultrasonic measurements. The 3D impedance maps show promise as a powerful tool to characterize ultrasonic scattering sites of tissue. [Work supported by the University of Illinois Research Board.

  1. Effect of grazing flow on the acoustic impedance of Helmholtz resonators consisting of single and clustered orifices

    NASA Technical Reports Server (NTRS)

    Hersch, A. S.; Walker, B.

    1979-01-01

    A semiempirical fluid mechanical model is derived for the acoustic behavior of thin-walled single orifice Helmholtz resonators in a grazing flow environment. The incident and cavity sound fields are connected in terms of an orifice discharge coefficient whose values are determined experimentally using the two-microphone method. Measurements show that at high grazing flow speeds, acoustical resistance is almost linearly proportional to the grazing flow speed and almost independent of incident sound pressure. The corresponding values of reactance are much smaller and tend towards zero. For thicker-walled orifice plates, resistance and reactance were observed to be less sensitive to grazing flow as the ratio of plate thickness to orifice diameter increased. Loud tones were observed to radiate from a single orifice Helmholtz resonator due to interaction between the grazing flow shear layer and the resonator cavity. Measurements showed that the tones radiated at a Strouhal number equal to 0.26. The effects of grazing flow on the impedance of Helmholtz resonators consisting of clusters of orifices was also studied. In general, both resistance and reaction were found to be virtually independent of orifice relative spacing and number. These findings are valid with and without grazing flow.

  2. Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

    PubMed Central

    Travagliati, Marco; Shilton, Richie; Beltram, Fabio; Cecchini, Marco

    2013-01-01

    Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains. PMID:24022515

  3. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices.

  4. A model for the acoustic impedance of a perforated plate liner with multiple frequency excitation

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1971-01-01

    A nonlinear resistance model is used in the one-dimensional equations of motion with an arbitrary exciting pressure function. The effects of high amplitude fluid motion, grazing flow, and spectral excitation can be studied together. Sample calculations of acoustic resistances are presented using a high amplitude discrete tone superimposed upon a simulated white noise spectrum. The tone amplitude is varied and its effect is shown both with and without a grazing flow velocity.

  5. Graphical Acoustic Liner Design and Analysis Tool

    NASA Technical Reports Server (NTRS)

    Howerton, Brian M. (Inventor); Jones, Michael G. (Inventor)

    2016-01-01

    An interactive liner design and impedance modeling tool comprises software utilized to design acoustic liners for use in constrained spaces, both regularly and irregularly shaped. A graphical user interface allows the acoustic channel geometry to be drawn in a liner volume while the surface impedance calculations are updated and displayed in real-time. A one-dimensional transmission line model may be used as the basis for the impedance calculations.

  6. A Spherically-Shaped PZT Thin Film Ultrasonic Transducer with an Acoustic Impedance Gradient Matching Layer Based on a Micromachined Periodically Structured Flexible Substrate

    PubMed Central

    Feng, Guo-Hua; Liu, Wei-Fan

    2013-01-01

    This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel transducer. Based on a design of a lead titanium zirconium (PZT) micropillar array, the constructed gradient acoustic matching layer has much better acoustic transmission efficiency within a 20–50 MHz operation range compared to a matching layer with a conventional quarter-wavelength thickness Parylene deposition. To construct the transducer, periodic microcavities are built on a flexible copper sheet, and then the sheet forms a designed curvature with a ball shaping. After PZT slurry deposition, the constructed PZT micropillar array is released onto a curved thin PZT layer. Following Parylene conformal coating on the processed PZT micropillars, the PZT micropillars and the surrounding Parylene comprise a matching layer with gradient acoustic impedance. By using the proposed technique, the fabricated transducer achieves a center frequency of 26 MHz and a −6 dB bandwidth of approximately 65%. PMID:24113683

  7. Measurement of Plasma Clotting Using Shear Horizontal Surface Acoustic Wave Sensor

    NASA Astrophysics Data System (ADS)

    Nagayama, Tatsuya; Kondoh, Jun; Oonishi, Tomoko; Hosokawa, Kazuya

    2013-07-01

    The monitoring of blood coagulation is important during operation. In this study, a shear horizontal surface acoustic wave (SH-SAW) sensor is applied to monitor plasma clotting. An SH-SAW sensor with a metallized surface for mechanical perturbation detection can detect plasma clotting. As plasma clotting is a gel formation reaction, the SH-SAW sensor detects viscoelastic property changes. On the other hand, an SH-SAW sensor with a free surface for electrical perturbation detection detects only the liquid mixing effect. No electrical property changes due to plasma clotting are obtained using this sensor. A planar electrochemical sensor is also used to monitor plasma clotting. In impedance spectral analysis, plasma clotting is measured. However, in the measurement of time responses, no differences between clotting and nonclotting are obtained. Therefore, the SH-SAW sensor is useful for monitoring plasma clotting.

  8. Electron mean free path dependence of the vortex surface impedance

    NASA Astrophysics Data System (ADS)

    Checchin, M.; Martinello, M.; Grassellino, A.; Romanenko, A.; Zasadzinski, J. F.

    2017-03-01

    In the present study the radio-frequency complex response of trapped vortices in superconductors is calculated and compared to experimental data previously published. The motion equation for a magnetic flux line is solved assuming a bi-dimensional and mean-free-path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the unprecedented bell-shaped trend as a function of the mean-free-path observed in our previous experimental work. We demonstrate that such bell-shaped trend of the surface resistance as a function of the mean-free-path may be described as the interplay of the two limiting regimes of the surface resistance, for low and large mean-free-path values: pinning and flux-flow regimes respectively. Since the possibility of defining the pinning potential at different locations from the surface and with different strengths, we discuss how the surface resistance is affected by different configurations of pinning sites. By tackling the frequency dependence of the surface resistance, we also demonstrate that the separation between pinning- and flux-flow-dominated regimes cannot be determined only by the depinning frequency. The dissipation regime can be tuned either by acting on the frequency or on the mean-free-path value.

  9. Surface acoustic wave devices for harsh environment wireless sensing

    DOE PAGES

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; ...

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensormore » with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.« less

  10. Surface acoustic wave devices for harsh environment wireless sensing

    SciTech Connect

    Greve, David W.; Chin, Tao -Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-05-24

    In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.

  11. Surface Acoustic Wave Devices for Harsh Environment Wireless Sensing

    PubMed Central

    Greve, David W.; Chin, Tao-Lun; Zheng, Peng; Ohodnicki, Paul; Baltrus, John; Oppenheim, Irving J.

    2013-01-01

    Langasite surface acoustic wave devices can be used to implement harsh-environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity. PMID:23708273

  12. Scattering from coated structures and antenna pattern control using impedance surfaces, part A/B

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Polka, Lesley A.; Liu, Kefeng

    1990-01-01

    The scattering from coated, conducting structures, specifically the coated dihedral corner reflector configuration and the coated strip/plate configuration is examined. The formulation uses impedance-wedge Uniform Theory of Diffraction scattering coefficients to calculate the diffracted fields. A finite-thickness coating is approximated using the impedance boundary condition to arrive at an equivalent impedance for the coating. The formulation of the impedance wedge coefficients is outlined. Far-field, perfectly conducting approximations are discussed. Problems with the present dihedral corner reflector model for certain angles of incidence and observation are discussed along with a potentially rectifying modification. Also, the capacity to measure the electromagnetic properties of lossy materials was developed. The effects of using multiple material coatings on the radiation pattern of the horn antenna were studied. Numerous computations were devoted toward the inverse problem of synthesizing desired radiation patterns using the impedance surfaces. Stabilizing the equivalent sheet impedance using the linear control condition was attempted, and it was found to be a very difficult task.

  13. Surface acoustic wave/silicon monolithic sensor/processor

    NASA Technical Reports Server (NTRS)

    Kowel, S. T.; Kornreich, P. G.; Nouhi, A.; Kilmer, R.; Fathimulla, M. A.; Mehter, E.

    1983-01-01

    A new technique for sputter deposition of piezoelectric zinc oxide (ZnO) is described. An argon-ion milling system was converted to sputter zinc oxide films in an oxygen atmosphere using a pure zinc oxide target. Piezoelectric films were grown on silicon dioxide and silicon dioxide overlayed with gold. The sputtered films were evaluated using surface acoustic wave measurements, X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and resistivity measurements. The effect of the sputtering conditions on the film quality and the result of post-deposition annealing are discussed. The application of these films to the generation of surface acoustic waves is also discussed.

  14. Observations of Brine Pool Surface Characteristics and Internal Structure Through Remote Acoustic and Structured Light Imaging

    NASA Astrophysics Data System (ADS)

    Smart, C.; Roman, C.; Michel, A.; Wankel, S. D.

    2015-12-01

    Observations and analysis of the surface characteristics and internal structure of deep-sea brine pools are currently limited to discrete in-situ observations. Complementary acoustic and structured light imaging sensors mounted on a remotely operated vehicle (ROV) have demonstrated the ability systematically detect variations in surface characteristics of a brine pool, reveal internal stratification and detect areas of active hydrocarbon activity. The presented visual and acoustic sensors combined with a stereo camera pair are mounted on the 4000m rated ROV Hercules (Ocean Exploration Trust). These three independent sensors operate simultaneously from a typical 3m altitude resulting in visual and bathymetric maps with sub-centimeter resolution. Applying this imaging technology to 2014 and 2015 brine pool surveys in the Gulf of Mexico revealed acoustic and visual anomalies due to the density changes inherent in the brine. Such distinct changes in acoustic impedance allowed the high frequency 1350KHz multibeam sonar to detect multiple interfaces. For instance, distinct acoustic reflections were observed at 3m and 5.5m below the vehicle. Subsequent verification using a CDT and lead line indicated the acoustic return from the brine surface was the signal at 3m, while a thicker muddy and more saline interface occurred at 5.5m, the bottom of the brine pool was not located but is assumed to be deeper than 15m. The multibeam is also capable of remotely detecting emitted gas bubbles within the brine pool, indicative of active hydrocarbon seeps. Bubbles associated with these seeps were not consistently visible above the brine while using the HD camera on the ROV. Additionally, while imaging the surface of brine pool the structured light sheet laser became diffuse, refracting across the main interface. Analysis of this refraction combined with varying acoustic returns allow for systematic and remote detection of the density, stratification and activity levels within and

  15. Evidence of surface paramagnetism in niobium and consequences for the superconducting cavity surface impedance.

    SciTech Connect

    Prolier, T.; Kharitonov, M.; Pellin, M.; Zasadzinski, J.; Ciovati, G.

    2011-06-01

    The presence of magnetic impurities in native niobium oxides have been confirmed by Point contact spectroscopy (PCT), SQUID magnetometry and Electron paramagnetic resonance (EPR). All niobium (Nb) samples displayed a small impurity contribution to the magnetic susceptibility at low temperatures which exhibited Curie-Weiss behavior, indicative of weakly coupled localized paramagnetic moments. By examining Nb samples with widely varying surface-to-volume ratios (rods, foils, wires, powders) it was found that the impurity contribution is correlated with surface area. Tunneling measurements which use the native oxide layers as barriers exhibit a zero-bias conductance peak which splits in a magnetic field >; 4T, consistent with the Appelbaum-Anderson model for spin flip tunneling. Viewed together the experiments strongly suggest that the native oxides of Nb are intrinsically defective, and consistently exhibit localized paramagnetic moments caused by oxygen vacancies in Nb{sub 2}O{sub 5}. The computation of the surface impedance (R{sub s}) in presence of magnetic impurities in the Shiba approximation reveals the saturation at low temperature of R{sub s}, suggesting that magnetic impurities are responsible for the so-called residual resistance. These properties may have an impact on Nb based superconducting devices and shine a new light on the origin of the paramagnetic Meissner effect (PME).

  16. Concentration dependence of nanochannel impedance and the determination of surface charge

    NASA Astrophysics Data System (ADS)

    Schiffbauer, Jarrod; Liel, Uri; Yossifon, Gilad

    2014-03-01

    In this paper, we demonstrate the variation of nanochannel impedance with bulk (reservoir) electrolyte concentration. The impedance of a nanochannel is shown to correspond to a characteristic deformed semicircular arc. The degree of deformation decreases with increasing concentration, and at a sufficiently low concentration the complex impedance saturates, becoming essentially independent of the reservoir concentration. This behavior is indicative of a surface-conduction dominant regime. Here we demonstrate that this effect extends beyond dc conductance and affects the ac response of the system as well, including both phase relationship and magnitude. The nanochannel resistance, obtained from low-voltage ac measurements, is then used to extract the nanochannel surface charge density. This is found to increase in magnitude with increasing electrolyte concentration.

  17. Thermal Boundary Resistance between GaN and Cubic Ice and THz Acoustic Attenuation Spectrum of Cubic Ice from Complex Acoustic Impedance Measurements.

    PubMed

    Mante, Pierre-Adrien; Chen, Chien-Cheng; Wen, Yu-Chieh; Sheu, Jinn-Kong; Sun, Chi-Kuang

    2013-11-27

    A phonon nanoscopy method, based on the picosecond ultrasonics technique, capable of studying the complex acoustic reflection coefficient at frequency up to 1 THz is proposed and demonstrated. By measuring the reflection coefficient at the same surface location at the interface between GaN and air, and between GaN and the material to characterize, we get access to the THz amplitude and phase spectra of the acoustic phonon reflection. The retrieval of both these pieces of information then allows the calculation of the attenuation in a wide range of frequency and gives new insight into the Kapitza anomaly. This method is then applied to cubic ice, and the measurements of the elastic properties, the phonon anharmonic decay spectrum up to 1 THz, as well as the measurements of the thermal phonon lifetime at 150 K are all achieved.

  18. Microfluidic particle manipulation using high frequency surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Ai, Ye; Collins, David J.

    2016-11-01

    Precise manipulation of particles and biological cells remains a very active research area in microfluidics. Among various force fields applied for microfluidic manipulations, acoustic waves have superior propagating properties in solids and fluids, which can readily enable non-contact cell manipulation in long operating distances. Exploiting acoustic waves for fluid and cell manipulation in microfluidics has led to a newly emerging research area, acoustofluidics. In this work, I will present particle and cell manipulation in microfluidics using high frequency surface acoustic waves (SAW). In particular, I will discuss a unique design of a focused IDT (FIDT) structure, which is able to generate a highly localized SAW field on the order of 20 µm wide. This highly focused acoustic beam has an effective manipulation area size that is comparable to individual micron-sized particles. Here, I demonstrate the use of this highly localized SAW field for single particle level sorting with sub-millisecond pulses and selective capture of particles. Based on the presented studies on acoustic particle manipulation, I envision that the merging of acoustics and microfluidics could enable various particle and cell manipulations needed in microfluidic applications. We acknowledge the support received from Singapore University of Technology and Design (SUTD)-Massachusetts Institute of Technology (MIT) International Design Center (IDG11300101) and SUTD Startup Research Grant (SREP13053) awarded to Y.A.

  19. Individually Identifiable Surface Acoustic Wave Sensors, Tags and Systems

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor); Solie, Leland P. (Inventor); Tucker, Dana Y. G. (Inventor); Hines, Andrew T. (Inventor)

    2017-01-01

    A surface-launched acoustic wave sensor tag system for remotely sensing and/or providing identification information using sets of surface acoustic wave (SAW) sensor tag devices is characterized by acoustic wave device embodiments that include coding and other diversity techniques to produce groups of sensors that interact minimally, reducing or alleviating code collision problems typical of prior art coded SAW sensors and tags, and specific device embodiments of said coded SAW sensor tags and systems. These sensor/tag devices operate in a system which consists of one or more uniquely identifiable sensor/tag devices and a wireless interrogator. The sensor device incorporates an antenna for receiving incident RF energy and re-radiating the tag identification information and the sensor measured parameter(s). Since there is no power source in or connected to the sensor, it is a passive sensor. The device is wirelessly interrogated by the interrogator.

  20. Drops subjected to surface acoustic waves: flow dynamics

    NASA Astrophysics Data System (ADS)

    Brunet, Philippe; Baudoin, Michael; Bou Matar, Olivier; Dynamique Des Systèmes Hors Equilibre Team; Aiman-Films Team

    2012-11-01

    Ultrasonic acoustic waves of frequency beyond the MHz are known to induce streaming flow in fluids that can be suitable to perform elementary operations in microfluidics systems. One of the currently appealing geometry is that of a sessile drop subjected to surface acoustic waves (SAW). Such Rayleigh waves produce non-trival actuation in the drop leading to internal flow, drop displacement, free-surface oscillations and atomization. We recently carried out experiments and numerical simulations that allowed to better understand the underlying physical mechanisms that couple acoustic propagation and fluid actuation. We varied the frequency and amplitude of actuation, as well as the properties of the fluid, and we measured the effects of these parameters on the dynamics of the flow. We compared these results to finite-elements numerical simulations.

  1. Standing surface acoustic wave (SSAW)-based cell washing

    PubMed Central

    Li, Sixing; Ding, Xiaoyun; Mao, Zhangming; Chen, Yuchao; Nama, Nitesh; Guo, Feng; Li, Peng; Wang, Lin; Cameron, Craig E.; Huang, Tony Jun

    2014-01-01

    Cell/bead washing is an indispensable sample preparation procedure used in various cell studies and analytical processes. In this article, we report a standing surface acoustic wave (SSAW)-based microfluidic device for cell and bead washing in a continuous flow. In our approach, the acoustic radiation force generated in a SSAW field is utilized to actively extract cells or beads from their original medium. A unique configuration of tilted-angle standing surface acoustic wave (taSSAW) is employed in our device, enabling us to wash beads with >98% recovery rate and >97% washing efficiency. We also demonstrate the functionality of our device by preparing high-purity (>97%) white blood cells from lysed blood samples through cell washing. Our SSAW-based cell/bead washing device has the advantages of label-free manipulation, simplicity, high biocompatibility, high recovery rate, and high washing efficiency. It can be useful for many lab-on-a-chip applications. PMID:25372273

  2. Single crystal metal wedges for surface acoustic wave propagation

    DOEpatents

    Fisher, E.S.

    1980-05-09

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  3. Single crystal metal wedges for surface acoustic wave propagation

    DOEpatents

    Fisher, Edward S.

    1982-01-01

    An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

  4. A surface acoustic wave technique for monitoring the growth behavior of small surface fatigue cracks

    SciTech Connect

    Resch, M.T.; Nelson, D.V.; Ramvsat, G.F.; Yuce, H.H.

    1985-03-01

    The theory of Kino and Auld which relates the reflection coefficient of acoustic waves from a crack to its size is summarized. A scattering model is evaluated from this theory concerning the reflection of surface acoustic waves (SAW) from a small surface fatigue crack at a frequency such that the crack depth is much smaller than the acoustic wavelength. Acoustic predictions of crack depth are compared to postfracture measurements of depth for small surface cracks in Pyrex glass, 7075-T651 aluminum, and 4340 steel. Additionally, the minimum detectable crack depth as limited by the acoustic noise level is determined for several typical aluminum and steel alloys. The utility of SAW reflection coefficient measurements for inferring crack depth, crack growth, and crack opening behavior in situ during fatigue cycling is discussed.

  5. Acoustic charge transport induced by the surface acoustic wave in chemical doped graphene

    NASA Astrophysics Data System (ADS)

    Zheng, Shijun; Zhang, Hao; Feng, Zhihong; Yu, Yuanyuan; Zhang, Rui; Sun, Chongling; Liu, Jing; Duan, Xuexin; Pang, Wei; Zhang, Daihua

    2016-10-01

    A graphene/LiNbO3 hybrid device is used to investigate the acoustic induced charge transport in chemical doped graphene. The chemical doping of graphene via its physisorption of gas molecules affects the surface acoustic wave (SAW) charge carrier transport in a manner different from electric field drift. That transport induces doping dependent macroscopic acoustoelectric current. The chemical doping can manipulate majority carriers and induces unique acoustoelectric features. The observation is explained by a classical relaxation model. Eventually the device based on acoustoelectric current is proved to outperform the common chemiresistor for chemicals. Our finding provides insight into acoustic charge carrier transport during chemical doping. The doping affects interaction of carriers with SAW phonon and facilitates the understanding of nanoscale acoustoelectric effect. The exploration inspires potential acoustoelectric application for chemical detection involving emerging 2D nanomaterials.

  6. Application of surface acoustic wave devices to radio telemetry

    NASA Technical Reports Server (NTRS)

    Strasilla, U.

    1983-01-01

    Three experimental Surface Acoustic Wave Resonators (SAWR) are developed and evaluated. A desired center frequency is obtained by correct spacing of the Inter-Digital Transducers (IDT). Transmitting and receiving IDT's must be close for adequate coupling and a sufficient number of reflectors are required to create a high quality standing wave. A review of oscillator theory is given and current technology evaluated.

  7. Acoustic Reflection from a Plane Boundary having Variable Surface Parameters

    DTIC Science & Technology

    1991-03-01

    1960). Mechanical waveguides. Pergamon Press . 10. Oppenheim, A.V. and Schafer, R.W. (1989). Discrete-time signal processing. Prentice Hall Signal...public release ANNOUNCEMENT Anouncement of this report is unlimited KEYWORDS Anechoic Coatings Surface Admittance Acoustic Reflectance ABSTRACT A

  8. Self-focusing of ion-acoustic surface waves

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1996-06-01

    An electrostatic ion-acoustic surface wave propagating along the boundary of a semi-infinite plasma is considered. It is shown that a nonlinear Schrödinger equation can describe the development of the wave amplitude. The self-focusing length of a wave beam is estimated.

  9. A New First-Principles Calculation of Field-Dependent RF Surface Impedance of BCS Superconductor

    SciTech Connect

    Xiao, Binping; Reece, Charles E.

    2014-02-01

    There is a need to understand the intrinsic limit of radiofrequency (RF) surface impedance that determines the performance of superconducting RF cavities in particle accelerators. Here we present a field-dependent derivation of Mattis-Bardeen theory of the RF surface impedance of BCS superconductors based on the shifted density of states resulting from coherently moving Cooper pairs. Our theoretical prediction of the effective BCS RF surface resistance (Rs) of niobium as a function of peak surface magnetic field amplitude agrees well with recently reported record low loss resonant cavity measurements from JLab and FNAL with carefully, yet differently, prepared niobium material. The surprising reduction in resistance with increasing field is explained to be an intrinsic effect.

  10. Noncontact detection of surface-breaking cracks using a laser acoustic source and an electromagnetic acoustic receiver

    SciTech Connect

    Dewhurst, R.J.; Edwards, C.; Palmer, S.B.

    1986-08-01

    An electromagnetic acoustic transducer (EMAT) is used to detect laser-generated surface acoustic transients. The surface acoustic waves are broadband and can be used to detect and size surface-breaking cracks if used in conjunction with a broadband detector. A broadband EMAT is described and its use to locate artificial surface-breaking defects in both aluminum and steel is demonstrated. A second study reveals that it can also be used for the detection of real surface-breaking cracks, even on rusty steel surfaces. 10 references.

  11. Synchronized photonic modulators driven by surface acoustic waves.

    PubMed

    Crespo-Poveda, A; Hey, R; Biermann, K; Tahraoui, A; Santos, P V; Gargallo, B; Muñoz, P; Cantarero, A; de Lima, M M

    2013-09-09

    Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180°-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms.

  12. Surface particulate contamination removal using noncontact acoustic traps (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wanis, Sam S.; Zhan, Mei Z.; Barsamian, Hagop

    2016-09-01

    We demonstrate that acoustic field-induced forces (FIF) can detach, trap, and translate particles with no physical contact. This technology thereby shows potential for cleaning optical surfaces without introducing damage to the surface as well as allowing for scale-up to cover large areas where an atmosphere exists such as prior to launch. Experiments relying on acoustic fields created a force field landscape in the region between a transducer and the contaminated glass surface. That force field was then responsible for removing dust particles, trapping them, and translating them to a repository site. We have established proof-of-principle through experiments that removed both well-controlled particles with a narrow diameter distribution, as well as Arizona road dust, with a wide diameter distribution from a glass surface.

  13. Design and optimization of a noise reduction system for infrasonic measurements using elements with low acoustic impedance.

    PubMed

    Alcoverro, Benoit; Le Pichon, Alexis

    2005-04-01

    The implementation of the infrasound network of the International Monitoring System (IMS) for the enforcement of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) increases the effort in the design of suitable noise reducer systems. In this paper we present a new design consisting of low impedance elements. The dimensioning and the optimization of this discrete mechanical system are based on numerical simulations, including a complete electroacoustical modeling and a realistic wind-noise model. The frequency response and the noise reduction obtained for a given wind speed are compared to statistical noise measurements in the [0.02-4] Hz frequency band. The effects of the constructive parameters-the length of the pipes, inner diameters, summing volume, and number of air inlets-are investigated through a parametric study. The studied system consists of 32 air inlets distributed along an overall diameter of 16 m. Its frequency response is flat up to 4 Hz. For a 2 m/s wind speed, the maximal noise reduction obtained is 15 dB between 0.5 and 4 Hz. At lower frequencies, the noise reduction is improved by the use of a system of larger diameter. The main drawback is the high-frequency limitation introduced by acoustical resonances inside the pipes.

  14. Subwavelength acoustic focusing by surface-wave-resonance enhanced transmission in doubly negative acoustic metamaterials

    SciTech Connect

    Zhou, Xiaoming; Badreddine Assouar, M. Oudich, Mourad

    2014-11-21

    We present analytical and numerical analyses of a yet unseen lensing paradigm that is based on a solid metamaterial slab in which the wave excitation source is attached. We propose and demonstrate sub-diffraction-limited acoustic focusing induced by surface resonant states in doubly negative metamaterials. The enhancement of evanescent waves across the metamaterial slab produced by their resonant coupling to surface waves is evidenced and quantitatively determined. The effect of metamaterial parameters on surface states, transmission, and wavenumber bandwidth is clearly identified. Based on this concept consisting of a wave source attached on the metamaterial, a high resolution of λ/28.4 is obtained with the optimum effective physical parameters, opening then an exciting way to design acoustic metamaterials for ultrasonic focused imaging.

  15. Acoustic Bubble Removal from Boiling Surfaces

    NASA Technical Reports Server (NTRS)

    Prosperetti, Andrea

    2002-01-01

    The object of the study was the investigation of the forces generated by standing acoustic waves on vapor bubbles, both far and near boundaries. In order to accomplish this objective, in view of the scarcity of publications on the topic, it has been necessary to build an edifice of knowledge about vapor bubbles in sound and flow fields from the ground up, as it were. We have addressed problems of gradually greater difficulty as follows: 1. In the first place, the physics of an stationary isolated bubble subject to a sound field in an unbounded liquid was addressed; 2. The case of bubbles translating in a stationary pressure field was then considered; 3. This was followed by a study of the combined effects of sound and translation, 4. And of a neighboring boundary 5. Finally, a new method to deal with nonspherical bubbles was developed- In addition to the work on vapor bubbles, some studies on gas bubbles were conducted in view of NASA's interest in the phenomenon of sonoluminescence.

  16. Optimizing surface acoustic wave sensors for trace chemical detection

    SciTech Connect

    Frye, G.C.; Kottenstette, R.J.; Heller, E.J.

    1997-06-01

    This paper describes several recent advances for fabricating coated surface acoustic wave (SAW) sensors for applications requiring trace chemical detection. Specifically, we have demonstrated that high surface area microporous oxides can provide 100-fold improvements in SAW sensor responses compared with more typical polymeric coatings. In addition, we fabricated GaAs SAW devices with frequencies up to 500 MHz to provide greater sensitivity and an ideal substrate for integration with high-frequency electronics.

  17. Estimation of Sea Surface Wave Spectra Using Acoustic Tomography.

    DTIC Science & Technology

    1987-09-01

    develops a new technique for estimating quasi- homogeneous and quasi-stationary sea surface wave frequency-direction spectra using acoustic tomog...problems for the homogeneous and quasi- homogeneous frequency-direction spectrum are introduced. The theory is ap- plied tosynthetic data which simulate...thesis introduces a technique that estimates the quasi-stationary and quasi- homogeneous sea surface wave frequency-direction spectrum from the spectra of

  18. Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-Qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2015-06-01

    Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices.

  19. Dispersionless Manipulation of Reflected Acoustic Wavefront by Subwavelength Corrugated Surface.

    PubMed

    Zhu, Yi-Fan; Zou, Xin-Ye; Li, Rui-Qi; Jiang, Xue; Tu, Juan; Liang, Bin; Cheng, Jian-Chun

    2015-06-16

    Free controls of optic/acoustic waves for bending, focusing or steering the energy of wavefronts are highly desirable in many practical scenarios. However, the dispersive nature of the existing metamaterials/metasurfaces for wavefront manipulation necessarily results in limited bandwidth. Here, we propose the concept of dispersionless wavefront manipulation and report a theoretical, numerical and experimental work on the design of a reflective surface capable of controlling the acoustic wavefront arbitrarily without bandwidth limitation. Analytical analysis predicts the possibility to completely eliminate the frequency dependence with a specific gradient surface which can be implemented by designing a subwavelength corrugated surface. Experimental and numerical results, well consistent with the theoretical predictions, have validated the proposed scheme by demonstrating a distinct phenomenon of extraordinary acoustic reflection within an ultra-broad band. For acquiring a deeper insight into the underlying physics, a simple physical model is developed which helps to interpret this extraordinary phenomenon and predict the upper cutoff frequency precisely. Generations of planar focusing and non-diffractive beam have also been exemplified. With the dispersionless wave-steering capability and deep discrete resolution, our designed structure may open new avenue to fully steer classical waves and offer design possibilities for broadband optical/acoustical devices.

  20. RETRACTION: Surface impedance determination of an object located over a planar PEC surface and its use in shape reconstruction Surface impedance determination of an object located over a planar PEC surface and its use in shape reconstruction

    NASA Astrophysics Data System (ADS)

    Seda Ünal, Gül; Yapar, Ali; Akduman, Ibrahim

    2009-06-01

    This paper has substantial overlap with the paper 'Reconstruction of surface impedance of an object located over a planar PEC surface' by Gül Seda Ünal, Mehmet Çayören and Evrim Tetik (2008 Journal of Physics: Conference Series 135 012099). Therefore this article has been retracted by IOP Publishing and by the authors, Gül Seda Ünal, Ali Yapar and Ibrahim Akduman.

  1. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Aldrigo, Martino; Dragoman, Mircea; Constanzo, Alessandra; Dragoman, Daniela

    2013-11-01

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  2. Graphene as a high impedance surface for ultra-wideband electromagnetic waves

    SciTech Connect

    Aldrigo, Martino; Costanzo, Alessandra; Dragoman, Mircea; Dragoman, Daniela

    2013-11-14

    The metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell surfaces able to suppress surface waves, which cause multipath interference and backward radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages better than a metal.

  3. Acoustics and Surface Pressure Measurements from Tandem Cylinder Configurations

    NASA Technical Reports Server (NTRS)

    Hutcheson, Florence V.; Brooks, Thomas F.; Lockard, David P.; Choudhari, Meelan M.; Stead, Daniel J.

    2014-01-01

    Acoustic and unsteady surface pressure measurements from two cylinders in tandem configurations were acquired to study the effect of spacing, surface trip and freestream velocity on the radiated noise. The Reynolds number ranged from 1.15x10(exp 5) to 2.17x10(exp 5), and the cylinder spacing varied between 1.435 and 3.7 cylinder diameters. The acoustic and surface pressure spectral characteristics associated with the different flow regimes produced by the cylinders' wake interference were identified. The dependence of the Strouhal number, peak Sound Pressure Level and spanwise coherence on cylinder spacing and flow velocity was examined. Directivity measurements were performed to determine how well the dipole assumption for the radiation of vortex shedding noise holds for the largest and smallest cylinder spacing tested.

  4. Langasite Surface Acoustic Wave Sensors: Fabrication and Testing

    SciTech Connect

    Zheng, Peng; Greve, David W.; Oppenheim, Irving J.; Chin, Tao-Lun; Malone, Vanessa

    2012-02-01

    We report on the development of harsh-environment surface acoustic wave sensors for wired and wireless operation. Surface acoustic wave devices with an interdigitated transducer emitter and multiple reflectors were fabricated on langasite substrates. Both wired and wireless temperature sensing was demonstrated using radar-mode (pulse) detection. Temperature resolution of better than ±0.5°C was achieved between 200°C and 600°C. Oxygen sensing was achieved by depositing a layer of ZnO on the propagation path. Although the ZnO layer caused additional attenuation of the surface wave, oxygen sensing was accomplished at temperatures up to 700°C. The results indicate that langasite SAW devices are a potential solution for harsh-environment gas and temperature sensing.

  5. Diffraction correction for precision surface acoustic wave velocity measurements

    NASA Astrophysics Data System (ADS)

    Ruiz M., Alberto; Nagy, Peter B.

    2002-09-01

    Surface wave dispersion measurements can be used to nondestructively characterize shot-peened, laser shock-peened, burnished, and otherwise surface-treated specimens. In recent years, there have been numerous efforts to separate the contribution of surface roughness from those of near-surface material variations, such as residual stress, texture, and increased dislocation density. As the accuracy of the dispersion measurements was gradually increased using state-of-the-art laser-ultrasonic scanning and sophisticated digital signal processing methods, it was recognized that a perceivable dispersive effect, similar to the one found on rough shot-peened specimens, is exhibited by untreated smooth surfaces as well. This dispersion effect is on the order of 0.1%, that is significantly higher than the experimental error associated with the measurements and comparable to the expected velocity change produced by near-surface compressive residual stresses in metals below their yield point. This paper demonstrates that the cause of this apparent dispersion is the diffraction of the surface acoustic wave (SAW) as it travels over the surface of the specimen. The results suggest that a diffraction correction may be introduced to increase the accuracy of surface wave dispersion measurements. A simple diffraction correction model was developed for surface waves and this correction was subsequently validated by laser-interferometric velocity measurements on aluminum specimens. copyright 2002 Acoustical Society of America.

  6. Full-circular surface acoustic wave excitation for high resolution acoustic microscopy using spherical lens and time gate technology.

    PubMed

    Ishikawa, I; Katakura, K; Ogura, Y

    1999-01-01

    With a fixed gate width under the condition where the focus of an acoustic lens was set inside the sample, we varied signal taking-in time. Discrimination was made between differences in time required for an ultrasonic signal reflected from the sample to reach the acoustic lens. This process also enabled three types of images to be obtained separately: the surface reflection wave image, a combination of images based on the interference of the surface reflection wave with surface acoustic waves, and the surface acoustic wave image. Thus it was presumed that this process also would reveal the causes of image contrast and allow an easy interpretation of images. Furthermore, the image resolution was improved, because the surface acoustic wave image was drawn by an ultrasonic beam produced by full-circular surface acoustic wave excitation propagating toward the center converging concentrically; the theoretical resolution was 0.4 times the value of the surface acoustic wave wavelength lambda(R) and independent of the defocus value of the acoustic lens. Several kinds of samples were observed with this method. The results showed that the new method permitted observation of the internal structures of samples while offering new knowledge through the data reflecting the ultrasonic wave damping and scatter drawn on the display.

  7. Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications

    NASA Astrophysics Data System (ADS)

    Timalsina, Yukta P.; Branen, Joshua; Aston, D. Eric; Noren, Kenneth; Corti, Giancarlo; Schumacher, Randi; McIlroy, David N.

    2011-07-01

    In this study, alternating current impedance spectroscopic analysis of the biofunctionalization process of a vertically-aligned (silica) nanosprings (VANS) surface is presented. The VANS surface is functionalized with a biotinylated immunoglobulin G (B-IgG) layer formed by physisorption of B-IgG from the solution phase. Bovine serum albumin passivation of the B-IgG layer reduces additional surface adsorption by blocking the potential sites of weak bond formation via electrostatic and hydrophobic interactions. As avidin acts as a receptor of biotinylated compounds, avidin conjugated glucose oxidase (Av-GOx) binds to the B-IgG layer via biotin. This avidin-biotin bond is a stable bond with high association affinity (Ka = 1015 M-1) that withstands wide variations in chemistry and pH. An IgG layer without biotin shows no binding to the Av-GOx, indicating that bonding is through the avidin-biotin interaction. Finally, fluoroscein iso-thiocyanate (FITC) labeled biotinylated bovine serum albumin (B-BSA) added to the Av-GOx surface is used to fluorescently label Av-GOx for fluorescent measurements that allow for the correlation of surface binding with impedance measurements. Modeling of impedance spectra measured after the addition of each biological solution indicates that the bimolecular layers behave as insulating layers. The impedance spectra for the VANS-based sensor are compared to simple parallel capacitor sensors, sans VANS, and serve as controls. VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls below 10 kHz. Changes in the magnitudes of the components of the VANS equivalent circuit indicate that the addition of biological layers changes the effective dielectric response of the VANS via the impediment of ionic motion and biomolecule polarization.

  8. Simulation Study on Semiconductor Coupled Surface Acoustic Wave Convolver through a Multi-Strip Electrodes

    NASA Astrophysics Data System (ADS)

    Hohkawa, Kohji; Suda, Takaya; Aoki, Yusuke; Kaneshiro, Chinami; Koh, Keishin

    2001-05-01

    This paper presents results of simulation study on a semiconductor coupled surface acoustic wave (SAW) convolver, in which the propagating SAW on a highly coupling coefficient piezoelectric substrate, couples with a bonded semiconductor diodes through multi-strip electrodes. We focus our study on a relatively wide band device which is the main feature of a highly efficiency device. By using a simple analysis and circuit simulator, based on the simulation program with integrated circuit emphasis (SPICE), we clarified the effect of device parameters, such as the shape of multi-strip tapping electrodes, characteristics of diode, impedance matching condition, kinds of transmission code and electro-mechanical coupling coefficient of SAW, on the device performances. We discussed the phenomenon, which cause the degradation, focusing on the frequency domain. We also clarified the essential problems of second order effect on the wide bandwidth device, which should be solved.

  9. Surface Acoustic Waves Enhance Neutrophil Killing of Bacteria

    PubMed Central

    Loike, John D.; Plitt, Anna; Kothari, Komal; Zumeris, Jona; Budhu, Sadna; Kavalus, Kaitlyn; Ray, Yonatan; Jacob, Harold

    2013-01-01

    Biofilms are structured communities of bacteria that play a major role in the pathogenicity of bacteria and are the leading cause of antibiotic resistant bacterial infections on indwelling catheters and medical prosthetic devices. Failure to resolve these biofilm infections may necessitate the surgical removal of the prosthetic device which can be debilitating and costly. Recent studies have shown that application of surface acoustic waves to catheter surfaces can reduce the incidence of infections by a mechanism that has not yet been clarified. We report here the effects of surface acoustic waves (SAW) on the capacity of human neutrophils to eradicate S. epidermidis bacteria in a planktonic state and within biofilms. Utilizing a novel fibrin gel system that mimics a tissue-like environment, we show that SAW, at an intensity of 0.3 mW/cm2, significantly enhances human neutrophil killing of S. epidermidis in a planktonic state and within biofilms by enhancing human neutrophil chemotaxis in response to chemoattractants. In addition, we show that the integrin CD18 plays a significant role in the killing enhancement observed in applying SAW. We propose from out data that this integrin may serve as mechanoreceptor for surface acoustic waves enhancing neutrophil chemotaxis and killing of bacteria. PMID:23936303

  10. Computer code for scattering from impedance bodies of revolution. Part 3: Surface impedance with s and phi variation. Analytical and numerical results

    NASA Technical Reports Server (NTRS)

    Uslenghi, Piergiorgio L. E.; Laxpati, Sharad R.; Kawalko, Stephen F.

    1993-01-01

    The third phase of the development of the computer codes for scattering by coated bodies that has been part of an ongoing effort in the Electromagnetics Laboratory of the Electrical Engineering and Computer Science Department at the University of Illinois at Chicago is described. The work reported discusses the analytical and numerical results for the scattering of an obliquely incident plane wave by impedance bodies of revolution with phi variation of the surface impedance. Integral equation formulation of the problem is considered. All three types of integral equations, electric field, magnetic field, and combined field, are considered. These equations are solved numerically via the method of moments with parametric elements. Both TE and TM polarization of the incident plane wave are considered. The surface impedance is allowed to vary along both the profile of the scatterer and in the phi direction. Computer code developed for this purpose determines the electric surface current as well as the bistatic radar cross section. The results obtained with this code were validated by comparing the results with available results for specific scatterers such as the perfectly conducting sphere. Results for the cone-sphere and cone-cylinder-sphere for the case of an axially incident plane were validated by comparing the results with the results with those obtained in the first phase of this project. Results for body of revolution scatterers with an abrupt change in the surface impedance along both the profile of the scatterer and the phi direction are presented.

  11. Scattering of electromagnetic waves from two-dimensional rough surfaces with an impedance approximation.

    PubMed

    Soriano, G; Saillard, M

    2001-01-01

    The sparse-matrix-flat-surface iterative approach has been implemented for perfectly conducting surfaces and modified to enhance convergence stability and speed for very rough surfaces. Monte Carlo simulations of backscattering enhancement using a beam decomposition technique are compared with millimeter-wave laboratory experimental data. Strong but finite conductivity for metals or thin skin depth for dielectrics is simulated by an impedance approximation. This gives rise to a nonhypersingular integral equation derived from the magnetic field integral equation. The effect of finite conductivity for a metal at visible wavelengths is shown.

  12. FROM THE CURRENT LITERATURE: Laser excitation of surface acoustic waves: a new direction in opto-acoustic spectroscopy of a solid

    NASA Astrophysics Data System (ADS)

    Karabutov, Aleksander A.

    1985-11-01

    Studies in thermo-optic excitation of surface acoustic waves are reviewed. The excitation of periodic and pulse signals is discussed, using nonmoving and moving beams. Most attention is paid to application of this effect for purposes of opto-acoustic spectroscopy of a solid. The possibilities and promises of using opto-acoustic spectroscopy (OAS) employing surface acoustic waves (SAW) are analyzed

  13. Design and Optimization of Broadband High Impedance Ground Planes (HIGP) for Surface Mount Antennas

    DTIC Science & Technology

    2008-03-01

    materials, all of these material parameters are negative. With these unusual material parameters, new kinds of miniaturized antennas and microwave devices... ANTENNAS THESIS Murat Dogrul, First Lieutenant, TUAF AFIT/GE/ENG/08-08 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF...United States Government. AFIT/GE/ENG/08-08 DESIGN AND OPTIMIZATION OF BROADBAND HIGH IMPEDANCE GROUND PLANES (HIGP) FOR SURFACE MOUNT ANTENNAS

  14. a Finite Difference Numerical Model for the Propagation of Finite Amplitude Acoustical Blast Waves Outdoors Over Hard and Porous Surfaces

    NASA Astrophysics Data System (ADS)

    Sparrow, Victor Ward

    1990-01-01

    This study has concerned the propagation of finite amplitude, i.e. weakly non-linear, acoustical blast waves from explosions over hard and porous media models of outdoor ground surfaces. The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous ground surface, which in the frequency domain exhibits a finite impedance, the linear phenomenological porous model of Morse and Ingard was used. The phenomenological equations are solved in the time domain for coupling with the time domain propagation solution in the air. The numerical solution is found through the method of finite differences. The second-order in time and fourth -order in space MacCormack method was used in the air, and the second-order in time and space MacCormack method was used in the porous medium modeling the ground. Two kinds of numerical absorbing boundary conditions were developed for the air propagation equations to truncate the physical domain for solution on a computer. Radiation conditions first were used on those sides of the domain where there were outgoing waves. Characteristic boundary conditions secondly are employed near the acoustic source. The numerical model agreed well with the Pestorius algorithm for the propagation of electric spark pulses in the free field, and with a result of Pfriem for normal plane reflection off a hard surface. In addition, curves of pressure amplification versus incident angle for waves obliquely incident on the hard and porous surfaces were produced which are similar to those in the literature. The model predicted that near grazing finite amplitude acoustic blast waves decay with distance over hard surfaces as r to the power -1.2. This result is consistent with the work of Reed. For propagation over the porous ground surface, the model predicted that this surface decreased the decay rate with distance for the larger blasts compared to the rate expected in the linear acoustics limit.

  15. Absorption of surface acoustic waves by topological insulator thin films

    SciTech Connect

    Li, L. L.; Xu, W.

    2014-08-11

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  16. Absorption of surface acoustic waves by topological insulator thin films

    NASA Astrophysics Data System (ADS)

    Li, L. L.; Xu, W.

    2014-08-01

    We present a theoretical study on the absorption of the surface acoustic waves (SAWs) by Dirac electrons in topological insulator (TI) thin films (TITFs). We find that due to momentum and energy conservation laws, the absorption of the SAWs in TITFs can only be achieved via intra-band electronic transitions. The strong absorption can be observed up to sub-terahertz frequencies. With increasing temperature, the absorption intensity increases significantly and the cut-off frequency is blue-shifted. More interestingly, we find that the absorption of the SAWs by the TITFs can be markedly enhanced by the tunable subgap in the Dirac energy spectrum of the TI surface states. Such a subgap is absent in conventional two-dimensional electron gases (2DEGs) and in the gapless Dirac 2DEG such as graphene. This study is pertinent to the exploration of the acoustic properties of TIs and to potential application of TIs as tunable SAW devices working at hypersonic frequencies.

  17. Comparison of Transmission Line Methods for Surface Acoustic Wave Modeling

    NASA Technical Reports Server (NTRS)

    Wilson, William; Atkinson, Gary

    2009-01-01

    Surface Acoustic Wave (SAW) technology is low cost, rugged, lightweight, extremely low power and can be used to develop passive wireless sensors. For these reasons, NASA is investigating the use of SAW technology for Integrated Vehicle Health Monitoring (IVHM) of aerospace structures. To facilitate rapid prototyping of passive SAW sensors for aerospace applications, SAW models have been developed. This paper reports on the comparison of three methods of modeling SAWs. The three models are the Impulse Response Method (a first order model), and two second order matrix methods; the conventional matrix approach, and a modified matrix approach that is extended to include internal finger reflections. The second order models are based upon matrices that were originally developed for analyzing microwave circuits using transmission line theory. Results from the models are presented with measured data from devices. Keywords: Surface Acoustic Wave, SAW, transmission line models, Impulse Response Method.

  18. Multiple-frequency surface acoustic wave devices as sensors

    NASA Astrophysics Data System (ADS)

    Ricco, Antonio J.; Martin, Stephen J.

    We have designed, fabricated, and tested a multiple-frequency acoustic wave (MUFAW) device on ST-cut quartz with nominal surface acoustic wave (SAW) center frequencies of 16, 40, 100, and 250 MHz. The four frequencies are obtained by patterning four sets of input and output interdigital transducers of differing periodicities on a single substrate. Such a device allows the frequency dependence of AW sensor perturbations to be examined, aiding in the elucidation of the operative interaction mechanism(s). Initial measurements of the SAW response to the vacuum deposition of a thin nickel film show the expected frequency dependence of mass sensitivity in addition to the expected frequency independence of the magnitude of the acoustoelectric effect. By measuring changes in both wave velocity and attenuation at multiple frequencies, extrinsic perturbations such as temperature and pressure changes are readily differentiated from one another and from changes in surface mass.

  19. Microwave Surface Impedance Measurements of SrFe2(As,P)2 Single Crystals

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideyuki; Imai, Yoshinori; Maeda, Atsutaka; Kitagawa, Kentaro; Matsubayashi, Kazuyuki; Takigawa, Masashi; Uwatoko, Yoshiya

    2012-02-01

    Various pairing symmetries have been proposed concerning Fe-based superconductors both theoretically and experimentally. It was reported that LaFePO[1] and BaFe2(As,P)2[2] have line nodes in their superconducting gap. It is in sharp contrast to other Fe-based compounds such as LiFeAs[3] and Fe(Se,Te)[4]. To confirm whether line nodes in gap function is a common feature among P doped systems, we measured the microwave surface impedances of SrFe2(As,P)2 single crystals (Tc˜30K). Single crystals were grown by self-flux method. The surface impedances were measured using a cavity perturbation technique. The imaginary part of surface impedance, which is proportional to London penetration depth in the superconducting state, shows a power law, λ(T)-λ(0)T^n. The power law indicates low-energy quasiparticle excitation, and an exponent slightly smaller than 2 does not exclude the possibility of the existence of line nodes. [ 1 ] J. D. Fletcher et al., Phys. Rev. Lett. 102 (2009) 147001.[ 2 ] K. Hashimoto et al., Phys. Rev. B 81 (2010) 220501(R).[ 3 ] Y. Imai et al., J. Phys. Soc. Jpn. 80 (2011) 013704.[ 4 ] H. Takahashi et al., Phys. Rev. B 84. (2011) 132503.

  20. Surface acoustic wave probe implant for predicting epileptic seizures

    DOEpatents

    Gopalsami, Nachappa [Naperville, IL; Kulikov, Stanislav [Sarov, RU; Osorio, Ivan [Leawood, KS; Raptis, Apostolos C [Downers Grove, IL

    2012-04-24

    A system and method for predicting and avoiding a seizure in a patient. The system and method includes use of an implanted surface acoustic wave probe and coupled RF antenna to monitor temperature of the patient's brain, critical changes in the temperature characteristic of a precursor to the seizure. The system can activate an implanted cooling unit which can avoid or minimize a seizure in the patient.

  1. Monolithic GaAs surface acoustic wave chemical microsensor array

    SciTech Connect

    HIETALA,VINCENT M.; CASALNUOVO,STEPHEN A.; HELLER,EDWIN J.; WENDT,JOEL R.; FRYE-MASON,GREGORY CHARLES; BACA,ALBERT G.

    2000-03-09

    A four-channel surface acoustic wave (SAW) chemical sensor array with associated RF electronics is monolithically integrated onto one GaAs IC. The sensor operates at 690 MHz from an on-chip SAW based oscillator and provides simple DC voltage outputs by using integrated phase detectors. This sensor array represents a significant advance in microsensor technology offering miniaturization, increased chemical selectivity, simplified system assembly, improved sensitivity, and inherent temperature compensation.

  2. Optimum contact conditions for miniaturized surface acoustic wave linear motor

    PubMed

    Takasaki; Kurosawa; Higuchi

    2000-03-01

    This paper reports the successful operation of a 70 MHz driving surface acoustic wave (SAW) linear motor with a miniaturized stator transducer. This paper also deals with an investigation into an optimized slider design for the miniaturized SAW linear motor. The performance of three silicon type sliders, with different projection size, was compared. Output forces of the three sliders were measured with change of pre-load. It was found that the slider with smaller projection tended to produce greater output force.

  3. Space manufacturing of surface acoustic wave devices, appendix D

    NASA Technical Reports Server (NTRS)

    Sardella, G.

    1973-01-01

    Space manufacturing of transducers in a vibration free environment is discussed. Fabrication of the masks, and possible manufacturing of the surface acoustic wave components aboard a space laboratory would avoid the inherent ground vibrations and the frequency limitation imposed by a seismic isolator pad. The manufacturing vibration requirements are identified. The concepts of space manufacturing are analyzed. A development program for manufacturing transducers is recommended.

  4. High-Temperature Surface-Acoustic-Wave Transducer

    NASA Technical Reports Server (NTRS)

    Zhao, Xiaoliang; Tittmann, Bernhard R.

    2010-01-01

    Aircraft-engine rotating equipment usually operates at high temperature and stress. Non-invasive inspection of microcracks in those components poses a challenge for the non-destructive evaluation community. A low-profile ultrasonic guided wave sensor can detect cracks in situ. The key feature of the sensor is that it should withstand high temperatures and excite strong surface wave energy to inspect surface/subsurface cracks. As far as the innovators know at the time of this reporting, there is no existing sensor that is mounted to the rotor disks for crack inspection; the most often used technology includes fluorescent penetrant inspection or eddy-current probes for disassembled part inspection. An efficient, high-temperature, low-profile surface acoustic wave transducer design has been identified and tested for nondestructive evaluation of structures or materials. The development is a Sol-Gel bismuth titanate-based surface-acoustic-wave (SAW) sensor that can generate efficient surface acoustic waves for crack inspection. The produced sensor is very thin (submillimeter), and can generate surface waves up to 540 C. Finite element analysis of the SAW transducer design was performed to predict the sensor behavior, and experimental studies confirmed the results. One major uniqueness of the Sol-Gel bismuth titanate SAW sensor is that it is easy to implement to structures of various shapes. With a spray coating process, the sensor can be applied to surfaces of large curvatures. Second, the sensor is very thin (as a coating) and has very minimal effect on airflow or rotating equipment imbalance. Third, it can withstand temperatures up to 530 C, which is very useful for engine applications where high temperature is an issue.

  5. Surface wave acoustics of granular packing under gravity

    SciTech Connect

    Clement, Eric; Andreotti, Bruno; Bonneau, Lenaic

    2009-06-18

    Due to the non-linearity of Hertzian contacts, the speed of sound in granular matter increases with pressure. For a packing under gravity and in the presence of a free surface, bulk acoustic waves cannot propagate due to the inherent refraction toward the surface (the mirage effect). Thus, only modes corresponding to surface waves (Raleigh-Hertz modes) are able to propagate the acoustic signal. First, based on a non-linear elasticity model, we describe the main features associated to these surface waves. We show that under gravity, a granular packing is from the acoustic propagation point of view an index gradient waveguide that selects modes of two distinct families i.e. the sagittal and transverse waves localized in the vicinity of the free surface. A striking feature of these surface waves is the multi-modal propagation: for both transverse and sagittal waves, we show the existence of a infinite but discrete series of propagating modes. In each case, we determine the mode shape and and the corresponding dispersion relation. In the case of a finite size system, a geometric waveguide is superimposed to the index gradient wave guide. In this later case, the dispersion relations are modified by the appearance of a cut-off frequency that scales with depth. The second part is devoted to an experimental study of surface waves propagating in a granular packing confined in a long channel. This set-up allows to tune a monomodal emission by taking advantage of the geometric waveguide features combined with properly designed emitters. For both sagittal and transverses waves, we were able to isolate a single mode (the fundamental one) and to plot the dispersion relation. This measurements agree well with the Hertzian scaling law as predicted by meanfield models. Furthermore, it allows us to determine quantitatively relations on the elastic moduli. However, we observe that our data yield a shear modulus abnormally weak when compared to several meanfield predictions.

  6. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    PubMed Central

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-01-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications. PMID:25425458

  7. Fast Response and High Sensitivity ZnO/glass Surface Acoustic Wave Humidity Sensors Using Graphene Oxide Sensing Layer

    NASA Astrophysics Data System (ADS)

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J. K.

    2014-11-01

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  8. Fast response and high sensitivity ZnO/glass surface acoustic wave humidity sensors using graphene oxide sensing layer.

    PubMed

    Xuan, Weipeng; He, Mei; Meng, Nan; He, Xingli; Wang, Wenbo; Chen, Jinkai; Shi, Tianjin; Hasan, Tawfique; Xu, Zhen; Xu, Yang; Luo, J K

    2014-11-26

    We report ZnO/glass surface acoustic wave (SAW) humidity sensors with high sensitivity and fast response using graphene oxide sensing layer. The frequency shift of the sensors is exponentially correlated to the humidity change, induced mainly by mass loading effect rather than the complex impedance change of the sensing layer. The SAW sensors show high sensitivity at a broad humidity range from 0.5%RH to 85%RH with < 1 sec rise time. The simple design and excellent stability of our GO-based SAW humidity sensors, complemented with full humidity range measurement, highlights their potential in a wide range of applications.

  9. Acoustic Techniques for Studying Soil-surface Seals and Crusts

    NASA Astrophysics Data System (ADS)

    Hickey, C. J.; Leary, D.; Dicarlo, D. A.

    2007-05-01

    The impact of raindrops on a soil surface during a rainstorm may cause soil-surface sealing and crusting. Soil- surface sealing is a result of the clogging in interaggregate pores by smaller suspended particles in the water, which reduces the infiltration capacity of soils. Soil-surface crusting refers to the increase in soil strength or mechanical stiffness associated with near surface compaction or densification. The formation of soil-surface seals and crusts have a profound influence on the erodability of soils, with the consensus being that the reduced hydraulic conductivity due to sealing is the more important factor. However, studies note that measured values of seal hydraulic conductivity are few. The reason so few measurements may be because the thickness of the altered surface layer is on the order of millimeters. For example Lee (2006) states that a soil-surface seal consist of two parts: a 0.1mm thick upper skin seal attributed to compaction by the rain drop impact and a deeper 1.5 mm "washed in" zone with decreased porosity due to the accumulation of particles. Bulk density profiles measured using X-radiography show maximum changes in the top 5 mm of the soil. The surface of the ground (soil) has an influence on the propagation of sound outdoors. The porosity, air flow- resistivity, and tortuosity of the ground are the properties, which characterize the influence of the ground on the airborne sound. The air flow-resistivity of a dry soil is equivalent to the hydraulic conductivity of a water-saturated soil. In this presentation we discuss two acoustic techniques, one with sensitivity to changes in hydraulic properties (sealing) and the other to changes in mechanical stiffness (crusting). These non-contact techniques excite the soil using a suspended loudspeaker to impinge acoustic energy from the air (sound) onto the sample. The response of the soil is quantified using a microphone to measure the total pressure above the soil surface and a laser Doppler

  10. Full-wave analysis of superconducting microstrip lines on anisotropic substrates using equivalent surface impedance approach

    SciTech Connect

    Lee, L.H.; Lyons, W.G.; Orlando, T.P.; Ali, S.M. . Dept. of Electrical Engineering and Computer Science); Lyons, W.G. . Lincoln Lab.); Withers, R.S. )

    1993-12-01

    A computationally efficient full-wave technique is developed to analyze single and coupled superconducting microstrip lines on anisotropic substrates. The optic axis of the dielectric is in the plane of the substrate at an arbitrary angle with respect to the propagation direction. A dyadic Green's function for layered, anisotropic media is used to formulate an integral equation for the current in the strips. To increase the efficiency of the method, the superconducting strips are replaced by equivalent surface impedances which account for the loss and kinetic inductance of the superconductors. The validity of this equivalent surface impedance (ESI) approach is verified by comparing the calculated complex propagation constant and characteristic impedance for superconducting microstrip lines on an isotropic substrate to measured results, and to numerical results by the more rigorous volume-integral equation method. The results calculated using the ESI approach for perfectly conducting coupled lines on an anisotropic substrate agree with the results by the finite-difference time-domain method. This efficient ESI technique is then used to study the effects of the optic axis orientation and the strip width on the characteristics of single and coupled superconducting microstrip lines on M-plane sapphire. The effects of the line separation and operating temperature on the coupled lines are also investigated.

  11. Microwave Imaging Using a Disordered Cavity with a Dynamically Tunable Impedance Surface

    NASA Astrophysics Data System (ADS)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

    2016-11-01

    We perform microwave imaging using a dynamically reconfigurable aperture based on a tunable disordered cavity. The electrically large cavity is cubic with a spherical deformation and supports a multitude of distinct electromagnetic modes that vary as a function of excitation frequency. With a set of irises introduced into one wall of the cavity, the cavity modes couple to spatially distinct radiative modes that vary as a function of the driving frequency. To increase the diversity of the radiated fields, we replace one of the cavity walls with a variable impedance surface consisting of a set of varactor-populated mushroom structures grouped into pixels. The reflection phase of each pixel is independently changed with application of a voltage bias, effectively altering the surface impedance. We demonstrate high-fidelity imaging and examine the role of the impedance-tunable boundary condition, revealing superior performance in comparison with just frequency-diverse measurements. We also demonstrate single-frequency imaging, which can significantly reduce the demands on the required microwave source. The dynamic cavity imager may find relevance in security screening, through-wall imaging, biomedical diagnostics, and radar applications.

  12. Development of AC impedance methods for evaluating corroding metal surfaces and coatings

    NASA Technical Reports Server (NTRS)

    Knockemus, Ward

    1986-01-01

    In an effort to investigate metal surface corrosion and the breakdown of metal protective coatings the AC Impedance Method was applied to zinc chromate primer coated 2219-T87 aluminum. The model 368-1 AC Impedance Measurement System recently acquired by the MSFC Corrosion Research Branch was used to monitor changing properties of coated aluminum disks immersed in 3.5% NaCl buffered at ph 5.5 over three to four weeks. The DC polarization resistance runs were performed on the same samples. The corrosion system can be represented by an electronic analog called an equivalent circuit that consists of transistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for resistances and capacities that can be assigned in the equivalent circuit following a least squares analysis of the data describe changes that occur on the corroding metal surface and in the protective coating. A suitable equivalent circuit was determined that predicts the correct Bode phase and magnitude for the experimental sample. The DC corrosion current density data are related to equivalent circuit element parameters.

  13. Laser method of acoustical emission control from vibrating surfaces

    NASA Astrophysics Data System (ADS)

    Motyka, Zbigniew

    2013-01-01

    For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

  14. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    The first surface acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposited on the acoustic propagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectic coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in Ne was demonstrated.

  15. Surface acoustic wave unidirectional transducers for quantum applications

    NASA Astrophysics Data System (ADS)

    Ekström, Maria K.; Aref, Thomas; Runeson, Johan; Björck, Johan; Boström, Isac; Delsing, Per

    2017-02-01

    The conversion efficiency of electric microwave signals into surface acoustic waves in different types of superconducting transducers is studied with the aim of quantum applications. We compare delay lines containing either conventional symmetric transducers (IDTs) or unidirectional transducers (UDTs) at 2.3 GHz and 10 mK. The UDT delay lines improve the insertion loss with 4.7 dB and a directivity of 22 dB is found for each UDT, indicating that 99.4% of the acoustic power goes in the desired direction. The power lost in the undesired direction accounts for more than 90% of the total loss in IDT delay lines, but only ˜3% of the total loss in the floating electrode unidirectional transducer delay lines.

  16. Scanning Michelson interferometer for imaging surface acoustic wave fields.

    PubMed

    Knuuttila, J V; Tikka, P T; Salomaa, M M

    2000-05-01

    A scanning homodyne Michelson interferometer is constructed for two-dimensional imaging of high-frequency surface acoustic wave (SAW) fields in SAW devices. The interferometer possesses a sensitivity of ~10(-5)nm/ radicalHz , and it is capable of directly measuring SAW's with frequencies ranging from 0.5 MHz up to 1 GHz. The fast scheme used for locating the optimum operation point of the interferometer facilitates high measuring speeds, up to 50,000 points/h. The measured field image has a lateral resolution of better than 1 mu;m . The fully optical noninvasive scanning system can be applied to SAW device development and research, providing information on acoustic wave distribution that cannot be obtained by merely electrical measurements.

  17. Visualization of Surface Acoustic Waves in Thin Liquid Films

    PubMed Central

    Rambach, R. W.; Taiber, J.; Scheck, C. M. L.; Meyer, C.; Reboud, J.; Cooper, J. M.; Franke, T.

    2016-01-01

    We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect. PMID:26917490

  18. Monolithic phononic crystals with a surface acoustic band gap from surface phonon-polariton coupling.

    PubMed

    Yudistira, D; Boes, A; Djafari-Rouhani, B; Pennec, Y; Yeo, L Y; Mitchell, A; Friend, J R

    2014-11-21

    We theoretically and experimentally demonstrate the existence of complete surface acoustic wave band gaps in surface phonon-polariton phononic crystals, in a completely monolithic structure formed from a two-dimensional honeycomb array of hexagonal shape domain-inverted inclusions in single crystal piezoelectric Z-cut lithium niobate. The band gaps appear at a frequency of about twice the Bragg band gap at the center of the Brillouin zone, formed through phonon-polariton coupling. The structure is mechanically, electromagnetically, and topographically homogeneous, without any physical alteration of the surface, offering an ideal platform for many acoustic wave applications for photonics, phononics, and microfluidics.

  19. Light scattering by surface acoustic waves on corrugated metal surfaces

    SciTech Connect

    Robertson, W.M.; Grimsditch, M. ); Moretti, A.L.; Kaufman, R.G.; Hulse, G.R. ); Fullerton, E.; Schuller, I.K. )

    1990-03-15

    We report the results of a Brillouin-scattering study of corrugated Ag surfaces. The corrugation plays a dramatic role in the wave-vector--selection rules governing coupling to surface phonons, and this effect is substantially different when the effective wave vector of the surface corrugation is collinear or perpendicular to the scattering plane. In processes that involve the grating wave vector, we show that the coupling mechanism between light and phonons is governed by surface plasmons which introduce a new scattering interaction with unusual polarization features in the Brillouin-scattering process.

  20. Surface acoustic wave micromotor with arbitrary axis rotational capability

    NASA Astrophysics Data System (ADS)

    Tjeung, Ricky T.; Hughes, Mark S.; Yeo, Leslie Y.; Friend, James R.

    2011-11-01

    A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

  1. Mapping of the ocean surface wind by ocean acoustic interferometers.

    PubMed

    Voronovich, Alexander G; Penland, Cécile

    2011-05-01

    Measurements of marine surface winds are crucial to understanding mechanical and thermodynamic forces on the ocean. Satellite measurements of surface winds provide global coverage but are problematic at high wind speeds. Acoustic techniques of wind speed retrieval, and even for tracking hurricanes, have been suggested as an alternative since wind is a strong source of ambient noise in the ocean. Such approaches involve near-local measurements with bottom-mounted hydrophones located close to the area of interest. This paper suggests a complementary approach: measuring directivity of low-frequency ambient noise in the horizontal plane. These measurements would employ long vertical line arrays (VLAs) spanning a significant portion of the ocean waveguide. Two VLAs separated by a distance of some tens of kilometers and coherently measuring acoustic pressure form a single ocean interferometer. By sampling the area of interest from different perspectives with at least two interferometers, marine surface winds might be mapped over horizontal scales of the order of 1000 km with about 10 km resolution (more specifically, the 10 km resolution here means that contribution from the basis functions representing surface wind field with the scale of spatial variations of the order of 10 km can be resolved; independent retrieval of the wind within 10(4) cells of a corresponding grid is hardly possible). An averaging time required to overcome statistical variability in the noise field is estimated to be about 3 h. Numerical simulations of propagation conditions typical for the North Atlantic Ocean are presented.

  2. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    1985-12-01

    The first surfce acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposted on the acoustic progagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectric coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in N2 has been demonstrated.

  3. Modeling of a Surface Acoustic Wave Strain Sensor

    NASA Technical Reports Server (NTRS)

    Wilson, W. C.; Atkinson, Gary M.

    2010-01-01

    NASA Langley Research Center is investigating Surface Acoustic Wave (SAW) sensor technology for harsh environments aimed at aerospace applications. To aid in development of sensors a model of a SAW strain sensor has been developed. The new model extends the modified matrix method to include the response of Orthogonal Frequency Coded (OFC) reflectors and the response of SAW devices to strain. These results show that the model accurately captures the strain response of a SAW sensor on a Langasite substrate. The results of the model of a SAW Strain Sensor on Langasite are presented

  4. The study of surface acoustic wave charge transfer device

    NASA Technical Reports Server (NTRS)

    Papanicolaou, N.; Lin, H. C.

    1978-01-01

    A surface acoustic wave-charge transfer device, consisting of an n-type silicon substrate, a thermally grown silicon dioxide layer, and a sputtered film of piezoelectric zinc oxide is proposed as a means of circumventing problems associated with charge-coupled device (CCD) applications in memory, signal processing, and imaging. The proposed device creates traveling longitudinal electric fields in the silicon and replaces the multiphase clocks in CCD's. The traveling electric fields create potential wells which carry along charges stored there. These charges may be injected into the wells by light or by using a p-n junction as in conventional CCD's.

  5. Surface Acoustic Wave Microwave Oscillator and Frequency Synthesizer.

    DTIC Science & Technology

    1980-06-01

    AD-A086 336 TRW DEFENSE AND SPACE SYSTEMS GROUP REDONDO BEACH CA F/ A /5 SURFACE ACOUSTIC WAVE MICROWA VE OSC ILLATOR AND FR EQUENCY SYNTME--ETC(U...DEVELOPMENT COMMAND FORT MONMOUTH, NEW JERSEY 07703 HISAŕ 78 UNCLASSIFIED 6 URTSfaceIO A si WHS ae Micowvef scilltr nermepteOt󈧫 BEFORE COEPETINFOR RE~~~ a ...D OKUI UBRj~ ~~n SpaReT ParkWCAIO OP T05HIS A .11eu.0t13..... IINCLASSTFTF[ gCUNTY CLASSIFICATION OF THIS PAOI(Whin DEla AIRIm Fminimum frequency step

  6. Surface acoustic wave vapor sensors based on resonator devices

    NASA Astrophysics Data System (ADS)

    Grate, Jay W.; Klusty, Mark

    1991-05-01

    Surface acoustic wave (SAW) devices fabricated in the resonator configuration have been used as organic vapor sensors and compared with delay line devices more commonly used. The experimentally determined mass sensitivities of 200, 300, and 400 MHz resonators and 158 MHz delay lines coated with Langmuir-Blodgett films of poly(vinyl tetradecanal) are in excellent agreement with theoretical predictions. The response of LB- and spray-coated sensors to various organic vapors were determined, and scaling laws for mass sensitivities, vapor sensitivities, and detection limits are discussed. The 200 MHz resonators provide the lowest noise levels and detection limits of all the devices examined.

  7. Surface acoustic wave devices including Langmuir-Blodgett films (Review)

    NASA Astrophysics Data System (ADS)

    Plesskii, V. P.

    1991-06-01

    Recent theoretical and experimental research related to the use of Langmuir-Blodgett (LB) films in surface acoustic wave (SAW) devices is reviewed. The sensitivity of the different cuts of quartz and lithium niobate to inertial loading is investigated, and it is shown that some cuts in lithium niobate are twice as sensitive to mass loading than the commonly used YZ-cut. The large variety of organic compounds suitable for the production of LB films makes it possible to create SAW sensors reacting selectively to certain substances. The existing SAW sensors based on LB films are characterized by high sensitivity and fast response.

  8. Beam reconfigurable antenna for the THz band based on a graphene high impedance surface

    NASA Astrophysics Data System (ADS)

    Radwan, Ahmed; Verri, Valentina; D'Amico, Michele; Gentili, G. Guido

    2017-01-01

    In this paper a reconfigurable beam antenna is proposed for THz applications, based on a switchable Graphene High Impedance Surface (G-HIS) that acts as a reflector for a primary radiator. The Graphene-HIS structure composed of two layers of graphene cells arranged in a 5×5 array, the two planes of the array are separated by a thin silicon oxide layer; patches in the same row are connected together, to be biased by a common DC voltage to the entire row; this gives the ability to control the graphene conductivity σ. The results show that the shape of the radiation pattern can be changed by changing the voltage applied to each row of G-HIS array. The antenna was fabricated and characterized using a THz-TDS laser system. Measurements are in good agreement with simulations as far as the graphene surface impedance and the resonance frequency are concerned. The scanning reflection on the antenna surface due to the change on the applied voltage is presented to show the effect of biased graphene layer on the dipole properties.

  9. Transport Powder and Liquid Samples by Surface Acoustic Waves

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Louyeh, Sahar

    2009-01-01

    Sample transport is an important requirement for In-situ analysis of samples in NASA planetary exploration missions. Tests have shown that powders or liquid drops on a surface can be transported by surface acoustic waves (SAW) that are generated on the surface using interdigital transducers. The phenomena were investigated experimentally and to generate SAWs interdigital electrodes were deposited on wafers of 128 deg rotated Y-cut LiNbO?. Transporting capability of the SAW device was tested using particles of various sizes and drops of various viscosities liquids. Because of different interaction mechanisms with the SAWs, the powders and the liquid drops were observed to move in opposite directions. In the preliminary tests, a speed of 180 mm/s was achieved for powder transportation. The detailed experimental setup and results are presented in this paper. The transporting mechanism can potentially be applied to miniaturize sample analysis system or " lab-on-chip" devices.

  10. Cyclodextrin-based surface acoustic wave chemical microsensors

    SciTech Connect

    Li, D.Q.; Shi, J.X.; Springer, K.; Swanson, B.I.

    1996-07-01

    Cyclodextrin thin films were fabricated using either self-assembled monolayer (SAM) or solgel techniques. The resulting host receptor thin films on the substrates of surface acoustic wave (SAW) resonators were studied as method of tracking organic toxins in vapor phase. The mass loading of surface-attached host monolayers on SAW resonators gave frequency shifts corresponding to typical monolayer surface coverages for SAM methods and ``multilayer`` coverages for sol-gel techniques. Subsequent exposure of the coated SAW resonators to organic vapors at various concentrations, typically 5,000 parts per millions (ppm) down to 100 parts per billions (ppb) by mole, gave responses indicating middle-ppb-sensitivity ({approximately}50 ppb) for those sensor-host-receptors and organic-toxin pairs with optimum mutual matching of polarity, size, and structural properties.

  11. Acoustic shadows help gleaning bats find prey, but may be defeated by prey acoustic camouflage on rough surfaces

    PubMed Central

    Clare, Elizabeth L; Holderied, Marc W

    2015-01-01

    Perceptual abilities of animals, like echolocating bats, are difficult to study because they challenge our understanding of non-visual senses. We used novel acoustic tomography to convert echoes into visual representations and compare these cues to traditional echo measurements. We provide a new hypothesis for the echo-acoustic basis of prey detection on surfaces. We propose that bats perceive a change in depth profile and an ‘acoustic shadow’ cast by prey. The shadow is more salient than prey echoes and particularly strong on smooth surfaces. This may explain why bats look for prey on flat surfaces like leaves using scanning behaviour. We propose that rather than forming search images for prey, whose characteristics are unpredictable, predators may look for disruptions to the resting surface (acoustic shadows). The fact that the acoustic shadow is much fainter on rougher resting surfaces provides the first empirical evidence for ‘acoustic camouflage’ as an anti-predator defence mechanism. DOI: http://dx.doi.org/10.7554/eLife.07404.001 PMID:26327624

  12. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures

    PubMed Central

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-01-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design. PMID:27035269

  13. Leaky-Wave Radiations by Modulating Surface Impedance on Subwavelength Corrugated Metal Structures.

    PubMed

    Cai, Ben Geng; Li, Yun Bo; Ma, Hui Feng; Jiang, Wei Xiang; Cheng, Qiang; Cui, Tie Jun

    2016-04-01

    One-dimensional (1D) subwavelength corrugated metal structures has been described to support spoof surface plasmon polaritons (SPPs). Here we demonstrate that a periodically modulated 1D subwavelength corrugated metal structure can convert spoof SPPs to propagating waves. The structure is fed at the center through a slit with a connected waveguide on the input side. The subwavelength corrugated metal structure on the output surface is regarded as metasurface and modulated periodically to realize the leaky-wave radiation at the broadside. The surface impedance of the corrugated metal structure is modulated by using cosine function and triangle-wave function, respectively, to reach the radiation effect. Full wave simulations and measuremental results are presented to validate the proposed design.

  14. Parabolic equation modeling of high frequency acoustic transmission with an evolving sea surface.

    PubMed

    Senne, J; Song, A; Badiey, M; Smith, K B

    2012-09-01

    The present paper examines the temporal evolution of acoustic fields by modeling forward propagation subject to sea surface dynamics with time scales of less than a second to tens of seconds. A time-evolving rough sea surface model is combined with a rough surface formulation of a parabolic equation model for predicting time-varying acoustic fields. Surface waves are generated from surface wave spectra, and stepped in time using a Runge-Kutta integration technique applied to linear evolution equations. This evolving, range-dependent surface information is combined with other environmental parameters and input to the acoustic model, giving an approximation of the time-varying acoustic field. The wide-angle parabolic equation model manages the rough sea surfaces by molding them into the boundary conditions for calculations of the near-surface acoustic field. This merged acoustic model is validated using concurrently-collected acoustic and environmental information, including surface wave spectra. Data to model comparisons demonstrate that the model is able to approximate the ensemble-averaged acoustic intensity at ranges of about a kilometer for acoustic signals of around 15 kHz. Furthermore, the model is shown to capture variations due to surface fluctuations occurring over time scales of less than a second to tens of seconds.

  15. Acoustically Induced Microparticle Orbiting and Clustering on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, A.; Tarimala, S.; Roberts, P. M.

    2008-12-01

    Behavior of colloidal particles in the bulk solution or at interfaces under the effect of high-frequency acoustics is critical to many seemingly different applications ranging from enhanced oil recovery to improved mixing in microfluidic channels and from accelerated contaminant extractions to surface cleaning, drug delivery and microelectronics. It can be detrimental or beneficial, depending on the application. In medical research, flow cytometry and microfluidics, for example, acoustically induced clustering of tracer particles and/or their sticking to the walls of channels, vessels, or tubes often becomes a problem. On the other hand, it can be tailored to enhance processes such as mixing in microfluidic devices, particle separation and sizing, and power generation microdevices. To better understand the underlying mechanisms, microscopic visualization experiments were performed in which polystyrene fluorescent (468/508 nm wavelength) microspheres with a mean diameter of 2.26-µm and density of 1.05 g/cm3, were suspended in either de-ionized water or a 0.1M NaCl solution. The freshly-prepared colloidal suspension was injected into a parallel-plate glass flow cell, which was subjected to high-frequency acoustics (200-500 kHz) through a piezoelectric transducer attached to one of the cell's outer walls. When the suspending medium is de-ionized water, acoustic stimulation of the cell at 313 kHz induced three distinct particle behaviors: 1) entrainment and bulk transport via wavelength-scale Rayleigh streaming, 2) transport via direct radiation forces to concentrate at nodal or anti-nodal planes, and 3) entrapment via boundary layer vorticular microstreaming resulting in mobile particles orbiting deposited particles. This latter phenomenon is intriguing. It occurs at specific frequencies and the shape of the orbits is determined by the applied frequency, whereas the rotation speed is proportional to the applied amplitude. At the higher ionic strength, on the other

  16. A comparison between the method based on a rigorous field analysis and the impedance transformation method for the intrinsic surface impedance of superconductor films

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Lee, Sang Young

    2006-10-01

    In obtaining the intrinsic surface resistance (RS) from the effective surface resistance (RS,eff) measured at microwave frequencies by using the dielectric resonator method, the impedance transformation method reported by Klein et al. [N. Klein, H. Chaloupka, G. Muller, S. Orbach, H. Piel, B. Roas, L. Schultz, U. Klein, M. Peiniger, J. Appl. Phys. 67 (1990) 6940] has been very useful. Here we compared the RS of YBa2Cu3O7-δ (YBCO) films on dielectric substrates obtained by a rigorous field analysis based on the TE-mode matching method with those by the impedance transformation method. The two methods produced almost the same RS,eff vs. RS relation in most practical cases of the substrate thickness being less than 1 mm and sapphire and rutile used as the materials for the dielectric rod. However, when the resonant frequency of the dielectric resonator became close to that of the resonant structure formed by the substrates and the metallic surroundings, the RS,eff vs. RS relations appeared strikingly different between the two methods. Effects of the TE011-mode cutoff frequency inside the substrate region, which could not be considered in the impedance transformation method, on the relation between the RS,eff and RS of superconductor films are also investigated. We confirmed our arguments by demonstrating a case where existence of evanescent modes should be considered for obtaining the RS of YBCO films from the RS,eff.

  17. Time-Domain Impedance Boundary Conditions for Computational Aeroacoustics

    NASA Technical Reports Server (NTRS)

    Tam, Christopher K. W.; Auriault, Laurent

    1996-01-01

    It is an accepted practice in aeroacoustics to characterize the properties of an acoustically treated surface by a quantity known as impedance. Impedance is a complex quantity. As such, it is designed primarily for frequency-domain analysis. Time-domain boundary conditions that are the equivalent of the frequency-domain impedance boundary condition are proposed. Both single frequency and model broadband time-domain impedance boundary conditions are provided. It is shown that the proposed boundary conditions, together with the linearized Euler equations, form well-posed initial boundary value problems. Unlike ill-posed problems, they are free from spurious instabilities that would render time-marching computational solutions impossible.

  18. Tunable nanowire patterning using standing surface acoustic waves.

    PubMed

    Chen, Yuchao; Ding, Xiaoyun; Steven Lin, Sz-Chin; Yang, Shikuan; Huang, Po-Hsun; Nama, Nitesh; Zhao, Yanhui; Nawaz, Ahmad Ahsan; Guo, Feng; Wang, Wei; Gu, Yeyi; Mallouk, Thomas E; Huang, Tony Jun

    2013-04-23

    Patterning of nanowires in a controllable, tunable manner is important for the fabrication of functional nanodevices. Here we present a simple approach for tunable nanowire patterning using standing surface acoustic waves (SSAW). This technique allows for the construction of large-scale nanowire arrays with well-controlled patterning geometry and spacing within 5 s. In this approach, SSAWs were generated by interdigital transducers, which induced a periodic alternating current (ac) electric field on the piezoelectric substrate and consequently patterned metallic nanowires in suspension. The patterns could be deposited onto the substrate after the liquid evaporated. By controlling the distribution of the SSAW field, metallic nanowires were assembled into different patterns including parallel and perpendicular arrays. The spacing of the nanowire arrays could be tuned by controlling the frequency of the surface acoustic waves. Additionally, we observed 3D spark-shaped nanowire patterns in the SSAW field. The SSAW-based nanowire-patterning technique presented here possesses several advantages over alternative patterning approaches, including high versatility, tunability, and efficiency, making it promising for device applications.

  19. Standing surface acoustic wave (SSAW)-based microfluidic cytometer

    PubMed Central

    Chen, Yuchao; Nawaz, Ahmad Ahsan; Zhao, Yanhui; Huang, Po-Hsun; McCoy, J. Phillip; Levine, Stewart; Wang, Lin; Huang, Tony Jun

    2014-01-01

    The development of microfluidic chip-based cytometers has become an important area due to their advantages of compact size and low cost. Herein, we demonstrate a sheathless microfluidic cytometer which integrates a standing surface acoustic wave (SSAW)-based microdevice capable of 3D particle/cell focusing with a laser-induced fluorescence (LIF) detection system. Using SSAW, our microfluidic cytometer was able to continuously focus microparticles/cells at the pressure node inside a microchannel. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of less than 10% at a throughput of ~1000 events/s when calibration beads were used. We also demonstrated that fluorescently labeled human promyelocytic leukemia cells (HL-60) could be effectively focused and detected with our SSAW-based system. This SSAW-based microfluidic cytometer did not require any sheath flows or complex structures, and it allowed for simple operation over a wide range of sample flow rates. Moreover, with the gentle, bio-compatible nature of low-power surface acoustic waves, this technique is expected to be able to preserve the integrity of cells and other bioparticles. PMID:24406848

  20. Acoustic measurement of the surface tension of levitated drops

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Marston, P. L.; Robey, J. L.

    1988-01-01

    The measurement of the frequency of the fundamental mode of shape oscillation of acoustically levitated drops has been carried out to determine the surface tension of the drop material. Sound fields of about 20 kHz in frequency allow the suspension of drops a few millimeters in size, as well as the necessary drive for oscillations. The surface tension of water, hexadecane, silicone oil, and aqueous solutions of glycerin levitated in air has been measured, and the results have been compared with those obtained with standard ring tensiometry. The two sets of data are in good agreement, the largest discrepancy being about 10 percent. Uncertainties in the effects of the nonspherical static shape of drops levitated in the earth's gravitational field and the rotation state of the sample are the major contributors to the experimental error. A decrease of the resonance frequency of the fundamental mode indicates a soft nonlinearity as the oscillation amplitude increases.

  1. New Biosensor Using Shear Horizontal Surface Acoustic Wave Device

    NASA Astrophysics Data System (ADS)

    Kondoh, Jun; Matsui, Yoshikazu; Shiokawa, Showko

    1993-05-01

    This paper describes a new biosensor to detect an enzyme reaction in liquid using surface acoustic wave (SAW) devices fabricated on 36°-rotated Y-cut, X-propagating LiTaO3. The sensing wave on the substrate is a predominantly shear-horizontal-mode SAW (SH-SAW) and is affected by a strong acoustoelectric interaction between the piezoelectric potential and electrical properties of the materials in the adjacent liquid. As an example of an electrical property, pH change associated with an enzyme reaction leads to measurable perturbation in the wave-propagation characteristic. Taking advantage of this phenomenon we realized a SAW biosensor which consists of an immobilized urease membrane on the surface. Also, highly sensitive detection for the urea solution was obtained in our preliminary experiments.

  2. Langasite surface acoustic wave gas sensors: modeling and verification

    SciTech Connect

    Peng Zheng,; Greve, D. W.; Oppenheim, I. J.

    2013-03-01

    We report finite element simulations of the effect of conductive sensing layers on the surface wave velocity of langasite substrates. The simulations include both the mechanical and electrical influences of the conducting sensing layer. We show that three-dimensional simulations are necessary because of the out-of-plane displacements of the commonly used (0, 138.5, 26.7) Euler angle. Measurements of the transducer input admittance in reflective delay-line devices yield a value for the electromechanical coupling coefficient that is in good agreement with the three-dimensional simulations on bare langasite substrate. The input admittance measurements also show evidence of excitation of an additional wave mode and excess loss due to the finger resistance. The results of these simulations and measurements will be useful in the design of surface acoustic wave gas sensors.

  3. Attenuation of 7 GHz surface acoustic waves on silicon

    NASA Astrophysics Data System (ADS)

    Li, Dongyao; Cahill, David G.

    2016-09-01

    We measured the attenuation of GHz frequency surface acoustic waves (SAWs) on the Si (001) surface using an optical pump-probe technique at temperatures between 300 and 600 K. SAWs are generated and detected by a 700 nm Al grating fabricated by nanoimprint lithography. The grating for SAW generation is separated from the grating for SAW detection by ≈150 μ m . The amplitude of SAWs is attenuated by coupling to bulk waves created by the Al grating, diffraction due to the finite size of the source, and the intrinsic relaxational Akhiezer damping of elastic waves in Si. Thermal phonon relaxation time and Grüneisen parameters are fitted using temperature-dependent measurement. The f Q product of a hypothetical micromechanical oscillator limited by Akhiezer damping at this frequency is ˜3 ×1013 Hz.

  4. Passive hypervelocity boundary layer control using an acoustically absortive surface

    NASA Astrophysics Data System (ADS)

    Rasheed, Adam

    A series of exploratory boundary layer transition experiments was performed on a sharp 5.06 degree half-angle round cone at zero angle-of-attack in the T5 Hypervelocity Shock Tunnel in order to test a novel hypersonic boundary layer control scheme. Recently performed linear stability analyses suggested that transition could be delayed in hypersonic boundary layers by using an ultrasonically absorptive surface that would damp the second mode (Mack mode). The cone used in the experiments was constructed with a smooth surface on half the cone (to serve as a control) and an acoustically absorptive porous surface on the other half. It was instrumented with flush-mounted thermocouples to detect the transition location. Test gases investigated included nitrogen and carbon dioxide at M = 5 with specific reservoir enthalpy ranging from 1.3 MJ/kg to 13.0 MJ/kg and reservoir pressure ranging from 9.0 MPa to 50.0 MPa. Detailed comparisons were performed to insure that previous results obtained in similar boundary layer transition experiments (on a regular smooth surface) were reproduced and the results were extended to examine the effects of the porous surface. These experiments indicated that the porous surface was highly effective in delaying transition provided that the hole size was significantly smaller than the viscous length scale.

  5. Electrochemical characterization of gelatinized starch dispersions: voltammetry and electrochemical impedance spectroscopy on platinum surface.

    PubMed

    Hernandez-Jaimes, C; Lobato-Calleros, C; Sosa, E; Bello-Pérez, L A; Vernon-Carter, E J; Alvarez-Ramirez, J

    2015-06-25

    The electrochemical properties of gelatinized starch dispersions (GSD; 5% w/w) from different botanical sources were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests over a platinum surface. The phenomenological modelling of EIS data using equivalent circuits indicated that after gelatinization the electrical resistance was determined mainly by the resistance of insoluble material (i.e., ghosts). Sonication of the GSD disrupted the ghost microstructure, and produced an increase in electrical conductivity by reducing the resistance of the insoluble material. The CV data showed three oxidation peaks at potentials where glucose solutions displayed oxidation waves. It is postulated that hydrolysis at the bulk and electrocatalyzed oxidation on the Pt-surface are reactions involved in the starch transformation. Starches peak intensity increased with the amylose content, suggesting that the amylose-rich matrix played an important role in the charge transfer in the electrolytic system.

  6. Surface properties of solids and surface acoustic waves: Application to chemical sensors and layer characterization

    NASA Astrophysics Data System (ADS)

    Krylov, V. V.

    1995-09-01

    A general phenomenological approach is given for the description of mechanical surface properties of solids and their influence on surface acoustic wave propogation. Surface properties under consideration may be changes of the stress distribution in subsurface atomic layers, the presence of adsorbed gas molecules, surface degradation as a result of impacts from an aggressive environment, damage due to mechanical manufacturing or polishing, deposition of thin films or liquid layers, surface corrugations, etc. If the characteristic thickness of the affected layers is much less than the wavelengths of the propagating surface waves, then the effects of all these irregularities can be described by means of non-classical boundary conditions incorporating the integral surface parameters such as surface tension, surface moduli of elasticity and surface mass density. The effect of surface properties on the propagation of Rayleigh surface waves is analysed in comparison with the results of traditional approaches, in particular with Auld's energy perturbation method. One of the important implications of the above-mentioned boudnary conditions is that they are adequate for the description of the effect of rarely distributed adsorbed atoms or molecules. This allows, in particular, to obtain a rigorous theoretical description of chemical sensors using surface acoustic waves and to derive analytical expressions for their sensitivity.

  7. Environmental Acoustics and Intensity Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface

    DTIC Science & Technology

    2014-09-30

    also advising PhD student Mr. Jeffrey Daniels, from the Acoustics Research Detachment (Bayview ID) Carderock Division, who has received an ILIR...2013. [2] D.R. Dall’Osto and P. H. Dahl, Elliptical acoustic particle motion in underwater waveguides , J. Acoust. Soc. Am., 134 (1), 109-118, July

  8. Determination of Surface Stress Distributions in Steel Using Laser-Generated Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Shi; Yifei; Ni; Chenyin; Shen; Zhonghua; Ni; Xiaowu; Lu; Jian

    2008-05-01

    High frequency surface acoustic waves (SAWs) are excited by a pulsed laser and detected by a specially designed poly(vinylidene fluoride) (PVDF) transducer to investigate surface stress distribution. Two kinds of stressed surfaces are examined experimentally. One is a steel plate elastically deformed under simple bending forces, where the surface stress varies slowly. The other is a welded steel plate for which the surface stress varies very rapidly within a small area near the welding seam. Applying a new signal processing method developed from correlation technique, the velocity distribution of the SAWs, which reflects the stress distribution, is obtained in these two samples with high resolution.

  9. Mass sensitivity of layered shear-horizontal surface acoustic wave devices for sensing applications

    NASA Astrophysics Data System (ADS)

    Kalantar-Zadeh, Kourosh; Trinchi, Adrian; Wlodarski, Wojtek; Holland, Anthony; Galatsis, Kosmas

    2001-11-01

    Layered Surface Acoustic Wave (SAW) devices that allow the propagation of Love mode acoustic waves will be studied in this paper. In these devices, the substrate allows the propagation of Surface Skimming Bulks Waves (SSBWs). By depositing layers, that the speed of Shear Horizontal (SH) acoustic wave propagation is less than that of the substrate, the propagation mode transforms to Love mode. Love mode devices which will be studied in this paper, have SiO2 and ZnO acoustic guiding layers. As Love mode of propagation has no movement of particles component normal to the active sensor surface, they can be employed for the sensing applications in the liquid media.

  10. Electrical properties of rat muscle after sciatic nerve injury: Impact on surface impedance measurements assessed via finite element analysis

    NASA Astrophysics Data System (ADS)

    Ahad, M. A.; Rutkove, S. B.

    2010-04-01

    Tetrapolar surface electrical impedance methods are sensitive to changes in muscle status and can therefore provide a means for studying neuromuscular disease noninvasively. In order to better understand the relationship between surface impedance measurements and the actual muscle electrical properties, we performed measurements on 20 adult Wistar rats, 8 of which underwent sciatic nerve crush. Surface impedance measurements were performed on the left hind limb both before injury and out to 2 weeks after injury. In addition, both normal and sciatic crush animals were sacrificed and the dielectric properties of the extracted gastrocnemius muscle measured. We found that 50 kHz conductivities were greater in the animals that underwent crush than in the animals that did not. The permittivities in both directions, however, showed non-significant differences. In order to analyze the effect of these changes as well as the accompanying reduction in muscle volume, a finite element model of the hind limb was developed based on computerized tomographic imaging. The model successfully predicted the surface impedance values in the animals after crush injury and, by its inverse application, may be used to help determine the underlying electrical properties of muscle in various neuromuscular diseases based on surface impedance data.

  11. Envelope solitons of acoustic plate modes and surface waves.

    PubMed

    Mayer, Andreas P; Kovalev, Alexander S

    2003-06-01

    The problem of the existence of evelope solitons in elastic plates and at solid surfaces covered by an elastic film is revisited with special attention paid to nonlinear long-wave short-wave interactions. Using asymptotic expansions and multiple scales, conditions for the existence of envelope solitons are established and it is shown how their parameters can be expressed in terms of the elastic moduli and mass densities of the materials involved. In addition to homogeneous plates, weak periodic modulation of the plate's material parameters are also considered. In the case of wave propagation in an elastic plate, modulations of weakly nonlinear carrier waves are governed by a coupled system of partial differential equations consisting of evolution equations for the complex amplitude of the carrier wave (the nonlinear Schrödinger equation for envelope solitons and the Mills-Trullinger equations for gap solitons), and the wave equation for long-wavelength acoustic plate modes. In contrast to this situation, envelope solitons of surface acoustic waves in a layered structure are normally described by the nonlinear Schrödinger equation alone. However, at higher orders of the carrier wave amplitude, the envelope soliton is found to be accompanied by a quasistatic long-wavelength strain field, which may be localized at the surface with penetration depth into the substrate of the order of the inverse amplitude or which may radiate energy into the bulk. A new set of modulation equations is derived for the resonant case of the carrier wave's group velocity being equal to the phase velocity of long-wavelength Rayleigh waves of the uncoated substrate.

  12. On-line surveillance of lubricants in bearings by means of surface acoustic waves.

    PubMed

    Lindner, Gerhard; Schmitt, Martin; Schubert, Josephine; Krempel, Sandro; Faustmann, Hendrik

    2010-01-01

    The acoustic wave propagation in bearings filled with lubricants and driven by pulsed excitation of surface acoustic waves has been investigated with respect to the presence and the distribution of different lubricants. Experimental setups, which are based on the mode conversion between surface acoustic waves and compression waves at the interface between a solid substrate of the bearing and a lubricant are described. The results of preliminary measurements at linear friction bearings, rotation ball bearings and axial cylinder roller bearings are presented.

  13. Spatial selective manipulation of microbubbles by tunable surface acoustic waves

    PubMed Central

    Zhou, Wei; Niu, Lili; Cai, Feiyan; Li, Fei; Wang, Chen; Huang, Xiaowei; Wang, Jingjing; Wu, Junru; Meng, Long; Zheng, Hairong

    2016-01-01

    A microfluidic device based on a pair of slant-finger interdigital transducers (SFITs) is developed to achieve a selective and flexible manipulation of microbubbles (MBs) by surface acoustic waves (SAWs). The resonance frequency of SAWs generated by the SFITs depends on the location of its parallel pathway; the particles at different locations of the SAWs' pathway can be controlled selectively by choosing the frequency of the excitation signal applied on the SFITs. By adjusting the input signal continuously, MBs can be transported along the acoustic aperture precisely. The displacement of MBs has a linear relationship with the frequency shift. The resolution of transportation is 15.19 ± 2.65 μm when the shift of input signal frequency is at a step of 10 kHz. In addition, the MBs can be controlled in a two-dimensional plane by combining variations of the frequency and the relative phase of the excitation signal applied on the SFITs simultaneously. This technology may open up the possibility of selectively and flexibly manipulating MBs using a simple one-dimensional device. PMID:27462381

  14. Acoustic Treatment Design Scaling Methods. Volume 4; Numerical Simulation of the Nonlinear Acoustic Impedance of a Perforated Plate Single-Degree-of-Freedom Resonator Using a Time-Domain Finite Difference Method

    NASA Technical Reports Server (NTRS)

    Kraft, R. E.

    1999-01-01

    Single-degree-of-freedom resonators consisting of honeycomb cells covered by perforated facesheets are widely used as acoustic noise suppression liners in aircraft engine ducts. The acoustic resistance and mass reactance of such liners are known to vary with the intensity of the sound incident upon the panel. Since the pressure drop across a perforated liner facesheet increases quadratically with the flow velocity through the facesheet, this is known as the nonlinear resistance effect. In the past, two different empirical frequency domain models have been used to predict the Sound Pressure Level effect of the incident wave on the perforated liner impedance, one that uses the incident particle velocity in isolated narrowbands, and one that models the particle velocity as the overall velocity. In the absence of grazing flow, neither frequency domain model is entirely accurate in predicting the nonlinear effect that is measured for typical perforated sheets. The time domain model is developed in an attempt to understand and improve the model for the effect of spectral shape and amplitude of multi-frequency incident sound pressure on the liner impedance. A computer code for the time-domain finite difference model is developed and predictions using the models are compared to current frequency-domain models.

  15. A Comparison of Surface Acoustic Wave Modeling Methods

    NASA Technical Reports Server (NTRS)

    Wilson, W. c.; Atkinson, G. M.

    2009-01-01

    Surface Acoustic Wave (SAW) technology is low cost, rugged, lightweight, extremely low power and can be used to develop passive wireless sensors. For these reasons, NASA is investigating the use of SAW technology for Integrated Vehicle Health Monitoring (IVHM) of aerospace structures. To facilitate rapid prototyping of passive SAW sensors for aerospace applications, SAW models have been developed. This paper reports on the comparison of three methods of modeling SAWs. The three models are the Impulse Response Method a first order model, and two second order matrix methods; the conventional matrix approach, and a modified matrix approach that is extended to include internal finger reflections. The second order models are based upon matrices that were originally developed for analyzing microwave circuits using transmission line theory. Results from the models are presented with measured data from devices.

  16. Multilayer-graphene-based amplifier of surface acoustic waves

    SciTech Connect

    Yurchenko, Stanislav O. Komarov, Kirill A.; Pustovoit, Vladislav I.

    2015-05-15

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C{sub 6v}, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  17. Application of acoustic surface wave technology to shuttle radar

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The application of surface acoustic wave (SAW) signal processing devices in the space shuttle was explored. In order to demonstrate the functions which a SAW device might perform, a breadboard pulse compression filter (PCF) module was assembled. The PCF permits a pulse radar to operate with a large duty cycle and low peak power, a regime favorable to the use of solid state RF sources. The transducer design, strong coupling compensation, circuit model analysis, fabrication limitations, and performance evaluation of a PCF are described. The nominal value of the compression ratio is 100:1 with 10-MHz bandwidth centered at 60 MHz and 10-microsecond dispersive delay. The PCF incorporates dispersive interdigital transducers and a piezoelectric lithium niobate substrate.

  18. Surface Acoustic Wave Tag-Based Coherence Multiplexing

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C. (Inventor); Malocha, Donald (Inventor); Saldanha, Nancy (Inventor)

    2016-01-01

    A surface acoustic wave (SAW)-based coherence multiplexing system includes SAW tags each including a SAW transducer, a first SAW reflector positioned a first distance from the SAW transducer and a second SAW reflector positioned a second distance from the SAW transducer. A transceiver including a wireless transmitter has a signal source providing a source signal and circuitry for transmitting interrogation pulses including a first and a second interrogation pulse toward the SAW tags, and a wireless receiver for receiving and processing response signals from the SAW tags. The receiver receives scrambled signals including a convolution of the wideband interrogation pulses with response signals from the SAW tags and includes a computing device which implements an algorithm that correlates the interrogation pulses or the source signal before transmitting against the scrambled signals to generate tag responses for each of the SAW tags.

  19. Surface acoustic wave sensing of VOCs in harsh chemical environments

    SciTech Connect

    Pfeifer, K.B.; Martin, S.J.; Ricco, A.J.

    1993-06-01

    The measurement of VOC concentrations in harsh chemical and physical environments is a formidable task. A surface acoustic wave (SAW) sensor has been designed for this purpose and its construction and testing are described in this paper. Included is a detailed description of the design elements specific to operation in 300{degree}C steam and HCl environments including temperature control, gas handling, and signal processing component descriptions. In addition, laboratory temperature stability was studied and a minimum detection limit was defined for operation in industrial environments. Finally, a description of field tests performed on steam reforming equipment at Synthetica Technologies Inc. of Richmond, CA is given including a report on destruction efficiency of CCl{sub 4} in the Synthetica moving bed evaporator. Design improvements based on the field tests are proposed.

  20. Surface acoustic wave coding for orthogonal frequency coded devices

    NASA Technical Reports Server (NTRS)

    Malocha, Donald (Inventor); Kozlovski, Nikolai (Inventor)

    2011-01-01

    Methods and systems for coding SAW OFC devices to mitigate code collisions in a wireless multi-tag system. Each device producing plural stepped frequencies as an OFC signal with a chip offset delay to increase code diversity. A method for assigning a different OCF to each device includes using a matrix based on the number of OFCs needed and the number chips per code, populating each matrix cell with OFC chip, and assigning the codes from the matrix to the devices. The asynchronous passive multi-tag system includes plural surface acoustic wave devices each producing a different OFC signal having the same number of chips and including a chip offset time delay, an algorithm for assigning OFCs to each device, and a transceiver to transmit an interrogation signal and receive OFC signals in response with minimal code collisions during transmission.

  1. Subharmonic phased array for crack evaluation using surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Ouchi, Akihiro; Sugawara, Azusa; Ohara, Yoshikazu; Yamanaka, Kazushi

    2015-07-01

    To accurately measure closed crack length, we proposed an imaging method using a subharmonic phased array for crack evaluation using surface acoustic waves (SAW SPACE) with water immersion. We applied SAW SPACE to the hole specimen in a fundamental array (FA) image. The hole was imaged with high resolution. Subsequently, SAW SPACE was applied to fatigue crack and stress corrosion crack (SCC) specimens. A fatigue crack was imaged in FA and subharmonic array (SA) images, and the length of this particular fatigue crack measured in the images was almost the same as that measured by optical observation. The SCC was imaged and its length was accurately measured in the SA image, whereas it was underestimated in the FA image and by optical observation. Thus, we demonstrated that SAW SPACE with water immersion is useful for the accurate measurement of closed crack length and for imaging the distribution of open and closed parts of cracks with high resolution.

  2. Multilayer-graphene-based amplifier of surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Yurchenko, Stanislav O.; Komarov, Kirill A.; Pustovoit, Vladislav I.

    2015-05-01

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann's equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein's and Rayleigh's SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C6v, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  3. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    NASA Technical Reports Server (NTRS)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  4. Surface acoustic-wave piezoelectric crystal aerosol mass microbalance

    NASA Astrophysics Data System (ADS)

    Bowers, W. D.; Chuan, R. L.

    1989-07-01

    The development of a particulate mass-sensing instrument based on a quartz-crystal microbalance and enhanced with the new surface acoustic-wave (SAW) technology is reported. Mass sensitivity comparisons of a 158-MHz SAW piezoelectric microbalance and a conventional 10-MHz quartz-crystal microbalance show that the SAW crystal is 266 times more sensitive, in good agreement with the theoretical value of 250. The frequency stability of a single SAW resonator is 6 parts in 10 to the 8th over 1 min. The response to temperature changes is found to be very linear over the range +30 to -30 C. A strong response to 15 ppm SO2 has been demonstrated on a chemically coated SAW crystal.

  5. Electric field imaging of a high impedance surface for GNSS array decoupling application

    NASA Astrophysics Data System (ADS)

    Prost, Daniel; Issac, François; Martel, Cédric; Capet, Nicolas; Sokoloff, Jérôme; Pascal, Olivier

    2015-10-01

    An original method of characterization of high impedance surfaces (HIS) is presented to exhibit electric field patterns. The electric field frames are obtained through a resistive film located in the near field domain of the HIS. The film heating is recorded using an infrared camera and gives after post-processing electric field magnitude profiles. We applied this technique to a HIS specially tuned for reducing mutual coupling in a global navigation satellite systems (GNSS) array designed for the E5 Galileo band. The mushroom-like HIS, designed and realized with the help of simulation, is located near the ground plane of a micro-strip line which allows S parameter characterization. Present measurement enables near field characterization and field structure analysis, and is therefore a complement to usual analysis. Moreover, the technique shows the very special field structure, including sub-lambda details, created by the HIS and more generally by metamaterial structures.

  6. Voltammetric and impedance behaviours of surface-treated nano-crystalline diamond film electrodes

    SciTech Connect

    Liu, F. B.; Jing, B.; Cui, Y.; Di, J. J.; Qu, M.

    2015-04-15

    The electrochemical performances of hydrogen- and oxygen-terminated nano-crystalline diamond film electrodes were investigated by cyclic voltammetry and AC impedance spectroscopy. In addition, the surface morphologies, phase structures, and chemical states of the two diamond films were analysed by scanning probe microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results indicated that the potential window is narrower for the hydrogen-terminated nano-crystalline diamond film than for the oxygen-terminated one. The diamond film resistance and capacitance of oxygen-terminated diamond film are much larger than those of the hydrogen-terminated diamond film, and the polarization resistances and double-layer capacitance corresponding to oxygen-terminated diamond film are both one order of magnitude larger than those corresponding to the hydrogen-terminated diamond film. The electrochemical behaviours of the two diamond film electrodes are discussed.

  7. Surface Impedance Formalism for a Metallic Beam Pipe with Small Corrugations

    SciTech Connect

    Stupakov, G.; Bane, K.L.F.; /SLAC

    2012-08-30

    A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant {epsilon} and magnetic permeability {mu}. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well.

  8. RF Surface Impedance Characterization of Potential New Materials for SRF-based Accelerators

    SciTech Connect

    Xiao, Binping; Eremeev, Grigory V.; Reece, Charles E.; Phillips, H. Lawrence; Kelley, Michael J.

    2012-09-01

    In the development of new superconducting materials for possible use in SRF-based accelerators, it is useful to work with small candidate samples rather than complete resonant cavities. The recently commissioned Jefferson Lab RF Surface Impedance Characterization (SIC) system can presently characterize the central region of 50 mm diameter disk samples of various materials from 2 to 40 K exposed to RF magnetic fields up to 14 mT at 7.4 GHz. We report the recent measurement results of bulk Nb, thin film Nb on Cu and sapphire substrates, Nb{sub 3}Sn sample, and thin film MgB{sub 2} on sapphire substrate provided by colleagues at JLab and Temple University.

  9. Electromagnetic and scalar diffraction by a right-angled wedge with a uniform surface impedance

    NASA Technical Reports Server (NTRS)

    Hwang, Y. M.

    1974-01-01

    The diffraction of an electromagnetic wave by a perfectly-conducting right-angled wedge with one surface covered by a dielectric slab or absorber is considered. The effect of the coated surface is approximated by a uniform surface impedance. The solution of the normally incident electromagnetic problem is facilitated by introducing two scalar fields which satisfy a mixed boundary condition on one surface of the wedge and a Neumann of Dirichlet boundary condition on the other. A functional transformation is employed to simplify the boundary conditions so that eigenfunction expansions can be obtained for the resulting Green's functions. The eigenfunction expansions are transformed into the integral representations which then are evaluated asymptotically by the modified Pauli-Clemmow method of steepest descent. A far zone approximation is made to obtain the scattered field from which the diffraction coefficient is found for scalar plane, cylindrical or sperical wave incident on the edge. With the introduction of a ray-fixed coordinate system, the dyadic diffraction coefficient for plane or cylindrical EM waves normally indicent on the edge is reduced to the sum of two dyads which can be written alternatively as a 2 X 2 diagonal matrix.

  10. Asymptotic expressions for the surface currents induced on a cylindrically curved impedance strip

    NASA Astrophysics Data System (ADS)

    Akduman, Ibrahim; Buyukaksoy, Alinur

    1995-05-01

    The present paper is concerned with the derivation of the electric and magnetic surface currents induced on a cylindrically curved impedance strip. By considering the locality of the high-frequency diffraction phenomena the physical (- pi, pi) interval for the usual cylindrical polar angle is replaced by an abstract infinite interval (- infinity, infinity) whereby the related mixed boundary value problem is formulated as a 'modified matrix Hilbert' problem. By using the Debye approximations for the Hankel and Bessel functions involved, the modified matrix Hilbert problem is first decoupled and then reduced to two pairs of simultaneous Fredholm integral equations of the second kind which are solved by iterations. The explicit expressions for the electric and magnetic surface current components attributable to the reflection, edge or surface diffractions of the incident field as well as to the edge reflections of these components themselves are obtained by evaluating the current integrals asymptotically. The results derived in this paper constitute also a rigorous proof for a conjecture made by Idemen on the reflections of the surface currents at the edges.

  11. Bubble-based acoustic micropropulsors: active surfaces and mixers.

    PubMed

    Bertin, Nicolas; Spelman, Tamsin A; Combriat, Thomas; Hue, Hervé; Stéphan, Olivier; Lauga, Eric; Marmottant, Philippe

    2017-04-11

    Acoustic micropropulsors present great potential for microfluidic applications. The propulsion is based on encapsulated 20 μm bubbles excited by a contacless ultrasonic transducer. The vibrating bubbles then generate a powerful streaming flow, with speeds 1-100 mm s(-1) in water, through the action of viscous stresses. In this paper we introduce a full toolbox of micropropulsors using a versatile three-dimensional (3D) microfabrication setup. Doublets and triplets of propulsors are introduced, and the flows they generate are predicted by a theoretical hydrodynamic model. We then introduce whole surfaces covered with propulsors, which we term active surfaces. These surfaces are excited by a single ultrasonic wave, can generate collective flows and may be harnessed for mixing purposes. Several patterns of propulsors are tested, and the flows produced by the two most efficient mixers are predicted by a simple theoretical model based on flow singularities. In particular, the vortices generated by the most efficient pattern, an L-shaped mixer, are analysed in detail.

  12. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation.

    PubMed

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-05-21

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  13. Surface Acoustic Wave (SAW) Resonators for Monitoring Conditioning Film Formation

    PubMed Central

    Hohmann, Siegfried; Kögel, Svea; Brunner, Yvonne; Schmieg, Barbara; Ewald, Christina; Kirschhöfer, Frank; Brenner-Weiß, Gerald; Länge, Kerstin

    2015-01-01

    We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application. PMID:26007735

  14. Dynamic Characterization of Dendrite Deposition and Growth in Li-Surface by Electrochemical Impedance Spectroscopy

    SciTech Connect

    Hernandez-Maya, R; Rosas, O; Saunders, J; Castaneda, H

    2015-01-13

    The evolution of dendrite formation is characterized by DC and AC electrochemical techniques. Interfacial mechanisms for lithium deposition are described and quantified by electrochemical impedance spectroscopy (EIS) between a lithium electrode and a graphite electrode. The initiation and growth of dendrites in the lithium surface due to the cathodic polarization conditions following anodic dissolution emulate long term cycling process occurring in the lithium electrodes. The dendrite initiation at the lithium/organic electrolyte interface is proposed to be performed through a combination of layering and interfacial reactions during different cathodic conditions. The growth is proposed to be performed by surface geometrical deposition. In this work, we use EIS in galvanostatic mode to assess the initiation and growth stages of dendrites by the accumulation of precipitates formed under different current conditions. The lithium/organic solvent experimental system using frequency domain techniques is validated by the theoretical approach using a deterministic model that accounts for the faradaic processes at the interface assuming a coverage fraction of the electrodic surface affected by the dendritic growth. (C) 2015 The Electrochemical Society. All rights reserved.

  15. Point source moving above a finite impedance reflecting plane - Experiment and theory

    NASA Technical Reports Server (NTRS)

    Norum, T. D.; Liu, C. H.

    1978-01-01

    A widely used experimental version of the acoustic monopole consists of an acoustic driver of restricted opening forced by a discrete frequency oscillator. To investigate the effects of forward motion on this source, it was mounted above an automobile and driven over an asphalt surface at constant speed past a microphone array. The shapes of the received signal were compared to results computed from an analysis of a fluctuating-mass-type point source moving above a finite impedance reflecting plane. Good agreement was found between experiment and theory when a complex normal impedance representative of a fairly hard acoustic surface was used in the analysis.

  16. Droplet Jumping Induced by Focused Surface Acoustic Wave on Superhydrophobic Surface

    NASA Astrophysics Data System (ADS)

    Darmawan, Marten; Jeon, Kwangsun; Byun, Doyoung

    2012-11-01

    We investigate the droplet jumping phenomena that are induced by focused surface acoustic wave on superhydrophobic surface. The utilization of an identical pair of single phase unidirectional transducers (SPUDTs) leads to the focusing of acoustic wave energy on a small region between them. This focused energy gives a very high acceleration as well as rapid interface destabilization to the liquid droplet and thus derives the jumping phenomenon once surpasses some Weber number's threshold value. We intriguingly investigate the effect of the small contact area of droplet on superhydrophobic surface, which is generated by using plasma treatment, to the droplet jetting phenomena and how it deforms under this circumstance. Furthermore, a parametric study, i.e. varying acoustic energy power, volume of droplet and degree of arc SPUDT, is also performed to investigate their effect on the elongated jumping droplet. Partially funded by Basic Science Research Program through the National Research Foundation of Korea (NRF, 2011-0016461) and the Industrial Core Technology Development Project through the Ministry of Knowledge and Commerce.

  17. Simulation of surface acoustic wave motor with spherical slider.

    PubMed

    Morita, T; Kurosawa, M K; Higuchi, T

    1999-01-01

    The operation of a surface acoustic wave (SAW) motor using spherical-shaped sliders was demonstrated by Kurosawa et al. (1994). It was necessary to modify the previous simulation models for usual ultrasonic motors because of this slider shape and the high frequency vibration. A conventional ultrasonic motor has a flat contact surface slider and a hundredth driving frequency; so, the tangential motion caused by the elasticity of the slider and stator with regard to the spherical slider of the SAW motor requires further investigation. In this paper, a dynamic simulation model for the SAW motor is proposed. From the simulation result, the mechanism of the SAW motor was clarified (i.e., levitation and contact conditions were repeated during the operation). The transient response of the motor speed was simulated. The relationships between frictional factor and time constant and vibration velocity of the stator and the slider speed were understood. The detailed research regarding the elastic deformation caused by preload would be helpful to construct an exact simulation model for the next work.

  18. Measuring The Electric Properties of Planetary Surface Materials With Mutual Impedance (mi) Probes

    NASA Astrophysics Data System (ADS)

    Trautner, R.; Grard, R.

    Mutual Impedance Probes have been developed for a number of ongoing space mis- sions. The HASI/PWA MI probe will determine the electric properties of the atmo- sphere and surface of Saturn's largest moon, Titan, in 2004. The Permittivity Probe of the SESAME instrument package on the Rosetta Lander will attempt to measure the conductivity and permittivity of the cometary surface material. While both instruments have similar objectives, their architecture (design and integration into the spacecraft, electrode geometry) and properties (measurement range and precision) differ signif- icantly. The main features of the Huygens PWA and Rosetta Lander SESAME MI probes are first recapitulated and their expected performances are assessed. A new MI probe prototype employing a linear electrode array for application on mobile platforms or penetrator devices is then described. Results from a recent field test campaign in the Australian desert are presented and the prototype performance is evaluated. New application areas for future MI probes and relevant technology requirements are dis- cussed.

  19. Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

    PubMed

    Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

    2012-08-07

    Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.

  20. Surface acoustic wave enabled pipette on a chip.

    PubMed

    Sesen, Muhsincan; Devendran, Citsabehsan; Malikides, Sean; Alan, Tuncay; Neild, Adrian

    2017-01-31

    Mono-disperse droplet formation in microfluidic devices allows the rapid production of thousands of identical droplets and has enabled a wide range of chemical and biological studies through repeat tests performed at pico-to-nanoliter volume samples. However, it is exactly this efficiency of production which has hindered the ability to carefully control the location and quantity of the distribution of various samples on a chip - the key requirement for replicating micro well plate based high throughput screening in vastly reduced volumetric scales. To address this need, here, we present a programmable microfluidic chip capable of pipetting samples from mobile droplets with high accuracy using a non-contact approach. Pipette on a chip (PoaCH) system selectively ejects (pipettes) part of a droplet into a customizable reaction chamber using surface acoustic waves (SAWs). Droplet pipetting is shown to range from as low as 150 pL up to 850 pL with precision down to tens of picoliters. PoaCH offers ease of integration with existing lab on a chip systems as well as a robust and contamination-free droplet manipulation technique in closed microchannels enabling potential implementation in screening and other studies.

  1. Controlling cell-cell interactions using surface acoustic waves.

    PubMed

    Guo, Feng; Li, Peng; French, Jarrod B; Mao, Zhangming; Zhao, Hong; Li, Sixing; Nama, Nitesh; Fick, James R; Benkovic, Stephen J; Huang, Tony Jun

    2015-01-06

    The interactions between pairs of cells and within multicellular assemblies are critical to many biological processes such as intercellular communication, tissue and organ formation, immunological reactions, and cancer metastasis. The ability to precisely control the position of cells relative to one another and within larger cellular assemblies will enable the investigation and characterization of phenomena not currently accessible by conventional in vitro methods. We present a versatile surface acoustic wave technique that is capable of controlling the intercellular distance and spatial arrangement of cells with micrometer level resolution. This technique is, to our knowledge, among the first of its kind to marry high precision and high throughput into a single extremely versatile and wholly biocompatible technology. We demonstrated the capabilities of the system to precisely control intercellular distance, assemble cells with defined geometries, maintain cellular assemblies in suspension, and translate these suspended assemblies to adherent states, all in a contactless, biocompatible manner. As an example of the power of this system, this technology was used to quantitatively investigate the gap junctional intercellular communication in several homotypic and heterotypic populations by visualizing the transfer of fluorescent dye between cells.

  2. Environmental Acoustics and Intensity Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface

    DTIC Science & Technology

    2013-09-30

    scientists), and Kevin Williams, all of APL-UW, and William Hodgkiss of SIO-MPL. The PI is also advising PhD student Mr. Jeffrey Daniels, from the...the University of Washington. PUBLICATIONS [1] D.R. Dall’Osto and P. H. Dahl, Elliptical acoustic particle motion in underwater waveguides , J...published, refereed] [3] D. R. Dall’Osto, Properties of the Acoustic Vector Field in Underwater Waveguides , Ph.D. thesis, Dept. Mechanical Engineering

  3. Slippery Liquid-Infused Porous Surfaces and Droplet Transportation by Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Luo, J. T.; Geraldi, N. R.; Guan, J. H.; McHale, G.; Wells, G. G.; Fu, Y. Q.

    2017-01-01

    On a solid surface, a droplet of liquid will stick due to the capillary adhesion, and this causes low droplet mobility. To reduce contact line pinning, surface chemistry can be coupled to micro- and/or nanostructures to create superhydrophobic surfaces on which a droplet balls up into an almost spherical shape, thus, minimizing the contact area. Recent progress in soft matter has now led to alternative lubricant-impregnated surfaces capable of almost zero contact line pinning and high droplet mobility without causing droplets to ball up and minimize the contact area. Here we report an approach to surface-acoustic-wave- (SAW) actuated droplet transportation enabled using such a surface. These surfaces maintain the contact area required for efficient energy and momentum transfer of the wave energy into the droplet while achieving high droplet mobility and a large footprint, therefore, reducing the threshold power required to induce droplet motion. In our approach, we use a slippery layer of lubricating oil infused into a self-assembled porous hydrophobic layer, which is significantly thinner than the SAW wavelength, and avoid damping of the wave. We find a significant reduction (up to 85%) in the threshold power for droplet transportation compared to that using a conventional surface-treatment method. Moreover, unlike droplets on superhydrophobic surfaces, where interaction with the SAW induces a transition from a Cassie-Baxter state to a Wenzel state, the droplets on our liquid-impregnated surfaces remain in a mobile state after interaction with the SAW.

  4. A re-expansion method for determining the acoustical impedance and the scattering matrix for the waveguide discontinuity problem

    PubMed Central

    Homentcovschi, Dorel; Miles, Ronald N.

    2010-01-01

    The paper gives a new method for analyzing planar discontinuities in rectangular waveguides. The method consists of a re-expansion of the normal modes in the two ducts at the junction plane into a system of functions accounting for the velocity singularities at the corner points. As the new expansion has an exponential convergence, only a few terms have to be considered for obtaining the solution of most practical problems. To see how the method works some closed form solutions, obtained by the conformal mapping method, are used to discuss the convergence of the re-expanded series when the number of retained terms increases. The equivalent impedance accounting for nonplanar waves into a plane-wave analysis is determined. Finally, the paper yields the scattering matrix which describes the coupling of arbitrary modes at each side of the discontinuity valid in the case of many propagating modes in both parts of the duct. PMID:20707432

  5. Physical optics theory for the diffraction of waves by impedance surfaces.

    PubMed

    Umul, Yusuf Ziya

    2011-02-01

    The solution of the scattering problem of waves by a half-screen with equal face impedances, which was introduced by Malyughinetz, is transformed into a physical optics integral by using the inverse edge point method. The obtained integral is applied to the diffraction problem of plane waves by an impedance truncated circular cylinder and the scattered waves are derived asymptotically. The results are examined numerically.

  6. Interface nano-confined acoustic waves in polymeric surface phononic crystals

    SciTech Connect

    Travagliati, Marco; Nardi, Damiano; Giannetti, Claudio; Ferrini, Gabriele; Banfi, Francesco; Gusev, Vitalyi; Pingue, Pasqualantonio; Piazza, Vincenzo

    2015-01-12

    The impulsive acoustic dynamics of soft polymeric surface phononic crystals is investigated here in the hypersonic frequency range by near-IR time-resolved optical diffraction. The acoustic response is analysed by means of wavelet spectral methods and finite element modeling. An unprecedented class of acoustic modes propagating within the polymer surface phononic crystal and confined within 100 nm of the nano-patterned interface is revealed. The present finding opens the path to an alternative paradigm for characterizing the mechanical properties of soft polymers at interfaces and for sensing schemes exploiting polymers as embedding materials.

  7. Interface nano-confined acoustic waves in polymeric surface phononic crystals

    NASA Astrophysics Data System (ADS)

    Travagliati, Marco; Nardi, Damiano; Giannetti, Claudio; Gusev, Vitalyi; Pingue, Pasqualantonio; Piazza, Vincenzo; Ferrini, Gabriele; Banfi, Francesco

    2015-01-01

    The impulsive acoustic dynamics of soft polymeric surface phononic crystals is investigated here in the hypersonic frequency range by near-IR time-resolved optical diffraction. The acoustic response is analysed by means of wavelet spectral methods and finite element modeling. An unprecedented class of acoustic modes propagating within the polymer surface phononic crystal and confined within 100 nm of the nano-patterned interface is revealed. The present finding opens the path to an alternative paradigm for characterizing the mechanical properties of soft polymers at interfaces and for sensing schemes exploiting polymers as embedding materials.

  8. Experimental observation of surface acoustic wave Brillouin scattering in a small-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Tchahame, Joël. Cabrel; Sylvestre, Thibaut; Phan Huy, Kien; Kudlinski, Alexandre; Laude, Vincent; Beugnot, Jean-Charles

    2016-04-01

    Light propagation in small-core photonic crystal fibers enables tight optical confinement over long propagation lengths to enhance light-matter interactions. Not only can photonic crystal fibers compress light spatially, they also provide a tunable means to control light-hypersound interactions. By exploring Brillouin light scattering in a small-core and high air-filling fraction microstructured fiber, we report the observation of Brillouin scattering from surface acoustic waves at lower frequencies than standard Brillouin scattering from bulk acoustic waves. This effect could find potential applications for optical sensing technologies that exploit surface acoustic waves.

  9. Surface acoustic wave devices as passive buried sensors

    NASA Astrophysics Data System (ADS)

    Friedt, J.-M.; Rétornaz, T.; Alzuaga, S.; Baron, T.; Martin, G.; Laroche, T.; Ballandras, S.; Griselin, M.; Simonnet, J.-P.

    2011-02-01

    Surface acoustic wave (SAW) devices are currently used as passive remote-controlled sensors for measuring various physical quantities through a wireless link. Among the two main classes of designs—resonator and delay line—the former has the advantage of providing narrow-band spectrum informations and hence appears compatible with an interrogation strategy complying with Industry-Scientific-Medical regulations in radio-frequency (rf) bands centered around 434, 866, or 915 MHz. Delay-line based sensors require larger bandwidths as they consists of a few interdigitated electrodes excited by short rf pulses with large instantaneous energy and short response delays but is compatible with existing equipment such as ground penetrating radar (GPR). We here demonstrate the measurement of temperature using the two configurations, particularly for long term monitoring using sensors buried in soil. Although we have demonstrated long term stability and robustness of packaged resonators and signal to noise ratio compatible with the expected application, the interrogation range (maximum 80 cm) is insufficient for most geology or geophysical purposes. We then focus on the use of delay lines, as the corresponding interrogation method is similar to the one used by GPR which allows for rf penetration distances ranging from a few meters to tens of meters and which operates in the lower rf range, depending on soil water content, permittivity, and conductivity. Assuming propagation losses in a pure dielectric medium with negligible conductivity (snow or ice), an interrogation distance of about 40 m is predicted, which overcomes the observed limits met when using interrogation methods specifically developed for wireless SAW sensors, and could partly comply with the above-mentioned applications. Although quite optimistic, this estimate is consistent with the signal to noise ratio observed during an experimental demonstration of the interrogation of a delay line buried at a depth of 5

  10. Monitoring polymer properties using shear horizontal surface acoustic waves.

    PubMed

    Gallimore, Dana Y; Millard, Paul J; Pereira da Cunha, Mauricio

    2009-10-01

    Real-time, nondestructive methods for monitoring polymer film properties are increasingly important in the development and fabrication of modern polymer-containing products. Online testing of industrial polymer films during preparation and conditioning is required to minimize material and energy consumption, improve the product quality, increase the production rate, and reduce the number of product rejects. It is well-known that shear horizontal surface acoustic wave (SH-SAW) propagation is sensitive to mass changes as well as to the mechanical properties of attached materials. In this work, the SH-SAW was used to monitor polymer property changes primarily dictated by variations in the viscoelasticity. The viscoelastic properties of a negative photoresist film were monitored throughout the ultraviolet (UV) light-induced polymer cross-linking process using SH-SAW delay line devices. Changes in the polymer film mass and viscoelasticity caused by UV exposure produced variations in the phase velocity and attenuation of the SH-SAW propagating in the structure. Based on measured polymer-coated delay line scattering transmission responses (S(21)) and the measured polymer layer thickness and density, the viscoelastic constants c(44) and eta(44) were extracted. The polymer thickness was found to decrease 0.6% during UV curing, while variations in the polymer density were determined to be insignificant. Changes of 6% in c(44) and 22% in eta(44) during the cross-linking process were observed, showing the sensitivity of the SH-SAW phase velocity and attenuation to changes in the polymer film viscoelasticity. These results indicate the potential for SH-SAW devices as online monitoring sensors for polymer film processing.

  11. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  12. Alternating current impedance spectroscopic analysis of biofunctionalized vertically-aligned silica nanospring surface for biosensor applications

    NASA Astrophysics Data System (ADS)

    Timalsina, Yukta P.

    In this dissertation, a process of vertically-aligned (silica) nanosprings (VANS) based biosensor development is presented. Alternating current (AC) impedance spectroscopy has been used to analyze sensor response as a function of saline phosphate (SP) buffer and biological solutions. The sensor is a parallel plate capacitor consisting of two glass substrates coated with indium tin oxide (ITO), where the VANS [or randomly-aligned nanosprings (RANS)] grown on one substrate serve as the dielectric spacer layer. The response of a VANS device as a function of ionic concentration in SP buffer was examined and an equivalent circuit model was developed. The results demonstrated that VANS sensors exhibited greater sensitivity to the changes in SP concentration relative to the ITO sensors, which serve as controls. The biofunctionalized VANS surface via physisorption and the cross-linker method demonstrates the repeatability, specificity, and selectivity of the binding. The physisorption of biotinylated immunoglobulin G (B-IgG) onto the VANS surface simplifies the whole sensing procedure for the detection of glucose oxidase, since the avidin-conjugated glucose oxidase (Av-GOx) can directly be immobilized on the B-IgG. The cross linker method involves the covalent attachment of antibodies onto the functionalized VANS surface via imine bond. The experiments revealed that the VANS sensor response is solely the result of the interaction of target molecule i.e. mouse IgG with the probe layer, i.e. goat antimouse IgG (GalphaM IgG). It was determined that VANS-based sensors exhibit a greater magnitude of change between successive bio-layers relative to the controls above 100 Hz, which indicates that the addition of biomolecules inhibits the diffusion of ions and changes the effective dielectric response of the VANS via biomolecular polarization. The study of ionic transport in nanosprings suggested that conductance follows a scaling law. It was demonstrated that a VANS-based device

  13. Strong Optomechanical Interaction in Hybrid Plasmonic-Photonic Crystal Nanocavities with Surface Acoustic Waves.

    PubMed

    Lin, Tzy-Rong; Lin, Chiang-Hsin; Hsu, Jin-Chen

    2015-09-08

    We propose dynamic modulation of a hybrid plasmonic-photonic crystal nanocavity using monochromatic coherent acoustic phonons formed by ultrahigh-frequency surface acoustic waves (SAWs) to achieve strong optomechanical interaction. The crystal nanocavity used in this study consisted of a defective photonic crystal beam coupled to a metal surface with a nanoscale air gap in between and provided hybridization of a highly confined plasmonic-photonic mode with a high quality factor and deep subwavelength mode volume. Efficient photon-phonon interaction occurs in the air gap through the SAW perturbation of the metal surface, strongly coupling the optical and acoustic frequencies. As a result, a large modulation bandwidth and optical resonance wavelength shift for the crystal nanocavity are demonstrated at telecommunication wavelengths. The proposed SAW-based modulation within the hybrid plasmonic-photonic crystal nanocavities beyond the diffraction limit provides opportunities for various applications in enhanced sound-light interaction and fast coherent acoustic control of optomechanical devices.

  14. Strong Optomechanical Interaction in Hybrid Plasmonic-Photonic Crystal Nanocavities with Surface Acoustic Waves

    PubMed Central

    Lin, Tzy-Rong; Lin, Chiang-Hsin; Hsu, Jin-Chen

    2015-01-01

    We propose dynamic modulation of a hybrid plasmonic-photonic crystal nanocavity using monochromatic coherent acoustic phonons formed by ultrahigh-frequency surface acoustic waves (SAWs) to achieve strong optomechanical interaction. The crystal nanocavity used in this study consisted of a defective photonic crystal beam coupled to a metal surface with a nanoscale air gap in between and provided hybridization of a highly confined plasmonic-photonic mode with a high quality factor and deep subwavelength mode volume. Efficient photon-phonon interaction occurs in the air gap through the SAW perturbation of the metal surface, strongly coupling the optical and acoustic frequencies. As a result, a large modulation bandwidth and optical resonance wavelength shift for the crystal nanocavity are demonstrated at telecommunication wavelengths. The proposed SAW-based modulation within the hybrid plasmonic-photonic crystal nanocavities beyond the diffraction limit provides opportunities for various applications in enhanced sound-light interaction and fast coherent acoustic control of optomechanical devices. PMID:26346448

  15. Nonlinear hydrodynamic effects induced by Rayleigh surface acoustic wave in sessile droplets.

    PubMed

    Alghane, M; Chen, B X; Fu, Y Q; Li, Y; Desmulliez, M P Y; Mohammed, M I; Walton, A J

    2012-11-01

    We report an experimental and numerical characterization of three-dimensional acoustic streaming behavior in small droplets of volumes (1-30 μl) induced by surface acoustic wave (SAW). We provide a quantitative evidence of the existence of strong nonlinear nature of the flow inertia in this SAW-driven flow over a range of the newly defined acoustic parameter F{NA}=Fλ/(σ/R_{d})≥0.01, which is a measure of the strength of the acoustic force to surface tension, where F is the acoustic body force, λ is the SAW wavelength, σ is the surface tension, and R{d} is the droplet radius. In contrast to the widely used Stokes model of acoustic streaming, which generally ignores such a nonlinearity, we identify that the full Navier-Stokes equation must be applied to avoid errors up to 93% between the computed streaming velocities and those from experiments as in the nonlinear case. We suggest that the Stokes model is valid only for very small acoustic power of ≤1 μW (F{NA}<0.002). Furthermore, we demonstrate that the increase of F{NA} above 0.45 induces not only internal streaming, but also the deformation of droplets.

  16. Two true surface acoustic waves and other acoustic modes in (110) plane of Li2B4O7 substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Victor Y.; Lefebvre, J. E.; Gryba, T.

    1999-09-01

    The surface acoustic waves (SAWs) and other acoustic modes propagating in the (110) plane of Li2B4O7 are investigated by means of the effective surface permittivity (ESP). It is demonstrated that the velocity of all piezoactive SAWs, both true and pseudo, as well as surface skimming bulk waves (SSBWs) can be numerically determined by computing the ESP as a function of acoustic trace slowness. A physical phenomenon not reported has been found for certain propagation directions, namely, simultaneous existence of two true SAWs, both being of the generalized Rayleigh type, together with a pseudo SAW of similar polarization. Propagation velocity, electromechanical coupling coefficient, and decay factor have been verified and confirmed by using two different sets of material constants and two numerical methods. The obtained values and accuracy of SAWs parameters are compared, and the validity conditions discussed. The generalized slowness diagram, plotted for the sagittal plane, enables to determine the total number of SSBW and to interpret the depth penetration properties of SAW. The Nyquist diagram of the ESP is shown to be a more helpful form for identifying a pseudo SAW and for distinguishing it from a SSBW.

  17. A theoretical study of the acoustic impedance of orifices in the presence of a steady grazing flow

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1976-01-01

    An analysis of the oscillatory fluid flow in the vicinity of a circular orifice with a steady grazing flow is presented. The study is similar to that of Hersh and Rogers but with the addition of the grazing flow. Starting from the momentum and continuity equations, a considerably simplified system of partial differential equations is developed with the assumption that the flow can be described by an oscillatory motion superimposed upon the known steady flow. The equations are seen to be linear in the region where the grazing flow effects are dominant, and a solution and the resulting orifice impedance are presented for this region. The nonlinearity appears to be unimportant for the usual conditions found in aircraft noise suppressors. Some preliminary conclusions of the study are that orifice resistance is directly proportional to grazing flow velocity (known previously from experimental data) and that the orifice inductive (mass reactance) end correction is not a function of grazing flow. This latter conclusion is contrary to the widely held notion that grazing flow removes the effect of the orifice inductive end correction. This conclusion also implies that the experimentally observed total inductance reduction with grazing flow might be in the flow within the orifice rather than in the end correction.

  18. Continuous micro-vortex-based nanoparticle manipulation via focused surface acoustic waves.

    PubMed

    Collins, David J; Ma, Zhichao; Han, Jongyoon; Ai, Ye

    2016-12-20

    Despite increasing demand in the manipulation of nanoscale objects for next generation biological and industrial processes, there is a lack of methods for reliable separation, concentration and purification of nanoscale objects. Acoustic methods have proven their utility in contactless manipulation of microscale objects mainly relying on the acoustic radiation effect, though the influence of acoustic streaming has typically prevented manipulation at smaller length scales. In this work, however, we explicitly take advantage of the strong acoustic streaming in the vicinity of a highly focused, high frequency surface acoustic wave (SAW) beam emanating from a series of focused 6 μm substrate wavelength interdigital transducers patterned on a piezoelectric lithium niobate substrate and actuated with a 633 MHz sinusoidal signal. This streaming field serves to focus fluid streamlines such that incoming particles interact with the acoustic field similarly regardless of their initial starting positions, and results in particle displacements that would not be possible with a travelling acoustic wave force alone. This streaming-induced manipulation of nanoscale particles is maximized with the formation of micro-vortices that extend the width of the microfluidic channel even with the imposition of a lateral flow, occurring when the streaming-induced flow velocities are an order of magnitude larger than the lateral one. We make use of this acoustic streaming to demonstrate the continuous and differential focusing of 100 nm, 300 nm and 500 nm particles.

  19. Determination of ammonium in Kjeldahl digests by gas-diffusion flow-injection analysis with a bulk acoustic wave-impedance sensor.

    PubMed

    Su, X L; Nie, L H; Yao, S Z

    1997-11-01

    A novel flow-injection analysis (FIA) system has been developed for the rapid and direct determination of ammonium in Kjeldahl digests. The method is based on diffusion of ammonia across a PTFE gas-permeable membrane from an alkaline (NaOH/EDTA) stream into a stream of diluted boric acid. The trapped ammonium in the acceptor is determined on line by a bulk acoustic wave (BAW)-impedance sensor and the signal is proportional to the ammonium concentration present in the digests. The proposed system exhibits a favorable frequency response to 5.0 x 10(-6)-4.0 x 10(-3) mol l(-1) ammonium with a detection limit of 1.0 x 10(-6) mol l(-1), and the precision was better than 1% (RSD) for 0.025-1.0 mM ammonium at a through-put of 45-50 samples h(-1). Results obtained for nitrogen determination in amino acids and for proteins determination in blood products are in good agreement with those obtained by the conventional distillation/titration method, respectively. The effects of composition of acceptor stream, cell constant of conductivity electrode, sample volume, flow rates and potential interferents on the FIA signals were discussed in detail.

  20. Bleustein-Gulyaev-Shimizu surface acoustic waves in two-dimensional piezoelectric phononic crystals.

    PubMed

    Hsu, Jin-Chen; Wu, Tsung-Tsong

    2006-06-01

    In this paper, we present a study on the existence of Bleustein-Gulyaev-Shimizu piezoelectric surface acoustic waves in a two-dimensional piezoelectric phononic crystal (zinc oxide, ZnO, and cadmium-sulfide, CdS) using the plane wave expansion method. In the configuration of ZnO (100)/CdS(100) phononic crystal, the calculated results show that this type of surface waves has higher acoustic wave velocities, high electromechanical coupling coefficients, and larger band gap width than those of the Rayleigh surface waves and pseudosurface waves. In addition, we find that the folded modes of the Bleustein-Gulyaev-Shimizu surface waves have higher coupling coefficients.

  1. Detection of rolling contact sub-surface fatigue cracks using acoustic emission technique

    SciTech Connect

    Yoshioka, T. )

    1993-04-01

    A method of locating the position of acoustic emission sources has been developed to analyze the mechanism of rolling contact fatigue. Using this method, sub-surface fatigue cracks were found at positions corresponding to the actual source positions of acoustic emissions. When fatigue tests were run under maximum stresses of 5.75 GPa and lubricant film parameters of 0.19, the cracks propagated parallel to the surface, had a maximum length of approximately 200 microns in the rolling direction of balls, and were distributed between 50 microns and 200 microns below the surface. Although the lubricant film parameter was small, no cracks from the surface were found. 12 refs.

  2. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    SciTech Connect

    Bertram, F. Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  3. Three-dimensional manipulation of single cells using surface acoustic waves.

    PubMed

    Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2016-02-09

    The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving "acoustic tweezers" in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner.

  4. Three-dimensional manipulation of single cells using surface acoustic waves

    PubMed Central

    Guo, Feng; Mao, Zhangming; Chen, Yuchao; Xie, Zhiwei; Lata, James P.; Li, Peng; Ren, Liqiang; Liu, Jiayang; Yang, Jian; Dao, Ming; Suresh, Subra; Huang, Tony Jun

    2016-01-01

    The ability of surface acoustic waves to trap and manipulate micrometer-scale particles and biological cells has led to many applications involving “acoustic tweezers” in biology, chemistry, engineering, and medicine. Here, we present 3D acoustic tweezers, which use surface acoustic waves to create 3D trapping nodes for the capture and manipulation of microparticles and cells along three mutually orthogonal axes. In this method, we use standing-wave phase shifts to move particles or cells in-plane, whereas the amplitude of acoustic vibrations is used to control particle motion along an orthogonal plane. We demonstrate, through controlled experiments guided by simulations, how acoustic vibrations result in micromanipulations in a microfluidic chamber by invoking physical principles that underlie the formation and regulation of complex, volumetric trapping nodes of particles and biological cells. We further show how 3D acoustic tweezers can be used to pick up, translate, and print single cells and cell assemblies to create 2D and 3D structures in a precise, noninvasive, label-free, and contact-free manner. PMID:26811444

  5. Broadband metamaterial for nonresonant matching of acoustic waves.

    PubMed

    D'Aguanno, G; Le, K Q; Trimm, R; Alù, A; Mattiucci, N; Mathias, A D; Aközbek, N; Bloemer, M J

    2012-01-01

    Unity transmittance at an interface between bulk media is quite common for polarized electromagnetic waves incident at the Brewster angle, but it is rarely observed for sound waves at any angle of incidence. In the following, we theoretically and experimentally demonstrate an acoustic metamaterial possessing a Brewster-like angle that is completely transparent to sound waves over an ultra-broadband frequency range with >100% bandwidth. The metamaterial, consisting of a hard metal with subwavelength apertures, provides a surface impedance matching mechanism that can be arbitrarily tailored to specific media. The nonresonant nature of the impedance matching effectively decouples the front and back surfaces of the metamaterial allowing one to independently tailor the acoustic impedance at each interface. On the contrary, traditional methods for acoustic impedance matching, for example in medical imaging, rely on resonant tunneling through a thin antireflection layer, which is inherently narrowband and angle specific.

  6. Environmental Acoustics and Intensity Vector Acoustics with Emphasis on Shallow Water Effects and the Sea Surface

    DTIC Science & Technology

    2012-09-30

    interference; for example how it relates directly the angles of interfering wavefronts and therefore reflection and refraction processes in a waveguide . We...intensity fields in an underwater waveguide through modification of the RAM parabolic wave equation (PE) code [3]. The vector products of the PE are used...advising PhD student Mr. Jeffrey Daniels, from the Acoustics Research Detachment (Bayview ID) Carderock Division, who has received an ILIR grant from

  7. Remote opto-acoustic probing of single-cell adhesion on metallic surfaces.

    PubMed

    Abi Ghanem, Maroun; Dehoux, Thomas; Zouani, Omar F; Gadalla, Atef; Durrieu, Marie-Christine; Audoin, Bertrand

    2014-06-01

    The reflection of picosecond ultrasonic pulses from a cell-substrate interface is used to probe cell-biomaterial adhesion with a subcell resolution. We culture monocytes on top of a thin biocompatible Ti metal film, supported by a transparent sapphire substrate. Low-energy femtosecond pump laser pulses are focused at the bottom of the Ti film to a micron spot. The subsequent ultrafast thermal expansion launches a longitudinal acoustic pulse in Ti, with a broad spectrum extending up to 100 GHz. We measure the acoustic echoes reflected from the Ti-cell interface through the transient optical reflectance changes. The time-frequency analysis of the reflected acoustic pulses gives access to a map of the cell acoustic impedance Zc and to a map of the film-cell interfacial stiffness K simultaneously. Variations in Zc across the cell are attributed to rigidity and density fluctuations within the cell, whereas variations in K are related to interfacial intermolecular forces and to the nano-architecture of the transmembrane bonds.

  8. Dynamic Response of X-37 Hot Structure Control Surfaces Exposed to Controlled Reverberant Acoustic Excitation

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Rizzi, Stephen A.; Rice, Chad E.

    2004-01-01

    This document represents a compilation of three informal reports from reverberant acoustic tests performed on X-37 hot structure control surfaces in the NASA Langley Research Center Structural Acoustics Loads and Transmission (SALT) facility. The first test was performed on a carbon-silicone carbide flaperon subcomponent on February 24, 2004. The second test was performed on a carbon-carbon ruddervator subcomponent on May 27, 2004. The third test was performed on a carbon-carbon flaperon subcomponent on June 30, 2004.

  9. On-Demand Droplet Capture and Release Using Microwell-Assisted Surface Acoustic Waves.

    PubMed

    Jung, Jin Ho; Destgeer, Ghulam; Park, Jinsoo; Ahmed, Husnain; Park, Kwangseok; Sung, Hyung Jin

    2017-02-21

    We demonstrate an acoustofluidic platform that uses surface acoustic waves (SAWs) for the facile capture of droplets inside microwells and their on-demand release. When the ac signal applied to the device is tuned to modulate the location of the SAW, the SAW-based acoustic radiation force retracts or pushes the droplets into or out of one of three microwells fabricated inside a microchannel to selectively capture or release the droplet.

  10. Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.

    PubMed

    Vadilonga, Simone; Zizak, Ivo; Roshchupkin, Dmitry; Evgenii, Emelin; Petsiuk, Andrei; Leitenberger, Wolfram; Erko, Alexei

    2017-04-01

    X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La3Ga5SiO14) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space-time modulation of an X-ray beam.

  11. Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry1

    PubMed Central

    Vadilonga, Simone; Zizak, Ivo; Roshchupkin, Dmitry; Evgenii, Emelin; Petsiuk, Andrei; Leitenberger, Wolfram; Erko, Alexei

    2017-01-01

    X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (La3Ga5SiO14) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice. Experimental results are compared with the corresponding theoretical model that exploits the kinematical diffraction theory. This experiment shows that the propagation of the surface acoustic waves creates a dynamical diffraction grating on the crystal surface, and this can be used for space–time modulation of an X-ray beam. PMID:28381976

  12. Improved Calibration Of Acoustic Plethysmographic Sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J.; Davis, David C.

    1993-01-01

    Improved method of calibration of acoustic plethysmographic sensors involves acoustic-impedance test conditions like those encountered in use. Clamped aluminum tube holds source of sound (hydrophone) inside balloon. Test and reference sensors attached to outside of balloon. Sensors used to measure blood flow, blood pressure, heart rate, breathing sounds, and other vital signs from surfaces of human bodies. Attached to torsos or limbs by straps or adhesives.

  13. Acoustic receptivity of compressible boundary layers: Receptivity by way of surface-temperature variations

    NASA Technical Reports Server (NTRS)

    Choudhari, Meelan

    1994-01-01

    The Goldstein-Ruban theory has been extended within the framework of Zavol'skii et al. to study the acoustic receptivity of compressible boundary layers. We consider the receptivity produced in a region of localized, small-amplitude variation in the surface temperature and compare it with the receptivity that is induced through a similar mechanism by a variation in the suction velocity at the surface. It is found that the orientation of the acoustic wave can have a significant impact on the receptivity process, with the maximum receptivity at a given sound-pressure level being produced by upstream oriented acoustic waves. At sufficiently low Mach numbers, the variation of receptivity with the acoustic-wave orientation can be predicted analytically and is the same for both surface suction and surface heating. However, as a result of the acoustic refraction across the mean boundary layer, the above dependence can become rather complex and, also, dependent on the type of surface nonuniformity. The results also suggest that the receptivity caused by temperature nonuniformities may turn out to be more significant than that produced by the mean-flow perturbations associated with strip suction.

  14. Construction and Testing of Broadband High Impedance Ground Planes (HIGPS) for Surface Mount Antennas

    DTIC Science & Technology

    2008-03-01

    mushrooms (with side lengths of 7.6mm). Larger mushrooms (with side lengths of 16mm) were located to the edges of the substrate . The resulting...thickness and substrate permittivity are two of the main design parameters. But these parameters have production constraints, since they are ordered off...plane designs as a meta- substrate for a broadband bow-tie antenna were presented. Consequently, the high impedance ground plane provided a suitable

  15. Acoustic-to-Seismic Coupling Over Porous Ground Surfaces.

    DTIC Science & Technology

    1984-01-01

    predictions based on these values and assumed values of grain shape factor ratio. Figure 4.2 comparison of measurements and predictions for characteristic ...and prediction for characteristic impedance in sands. Key as in 4.3 L Figure 4.5 Microphone Probe system for soils and sands Figure 4.6 Measured and...porosity "" Figure 5.2 Predicted sensitivity of fast-wpe characteristics in water-filled sana to grain shape factor Figure 5.3 Predicted sensitivity of

  16. Development and Validation of an Interactive Liner Design and Impedance Modeling Tool

    NASA Technical Reports Server (NTRS)

    Howerton, Brian M.; Jones, Michael G.; Buckley, James L.

    2012-01-01

    The Interactive Liner Impedance Analysis and Design (ILIAD) tool is a LabVIEW-based software package used to design the composite surface impedance of a series of small-diameter quarter-wavelength resonators incorporating variable depth and sharp bends. Such structures are useful for packaging broadband acoustic liners into constrained spaces for turbofan engine noise control applications. ILIAD s graphical user interface allows the acoustic channel geometry to be drawn in the liner volume while the surface impedance and absorption coefficient calculations are updated in real-time. A one-dimensional transmission line model serves as the basis for the impedance calculation and can be applied to many liner configurations. Experimentally, tonal and broadband acoustic data were acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3000 Hz at 120 and 140 dB SPL. Normalized impedance spectra were measured using the Two-Microphone Method for the various combinations of channel configurations. Comparisons between the computed and measured impedances show excellent agreement for broadband liners comprised of multiple, variable-depth channels. The software can be used to design arrays of resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.

  17. Acoustic imaging in application to reconstruction of rough rigid surface with airborne ultrasound waves

    NASA Astrophysics Data System (ADS)

    Krynkin, A.; Dolcetti, G.; Hunting, S.

    2017-02-01

    Accurate reconstruction of the surface roughness is of high importance to various areas of science and engineering. One important application of this technology is for remote monitoring of open channel flows through observing its dynamic surface roughness. In this paper a novel airborne acoustic method of roughness reconstruction is proposed and tested with a static rigid rough surface. This method is based on the acoustic holography principle and Kirchhoff approximation which make use of acoustic pressure data collected at multiple receiver points spread along an arch. The Tikhonov regularisation and generalised cross validation technique are used to solve the underdetermined system of equations for the acoustic pressures. The experimental data are collected above a roughness created with a 3D printer. For the given surface, it is shown that the proposed method works well with the various number of receiver positions. In this paper, the tested ratios between the number of surface points at which the surface elevation can be reconstructed and number of receiver positions are 2.5, 5, and 7.5. It is shown that, in a region comparable with the projected size of the main directivity lobe, the method is able to reconstruct the spatial spectrum density of the actual surface elevation with the accuracy of 20%.

  18. Surface Roughness Evaluation Based on Acoustic Emission Signals in Robot Assisted Polishing

    PubMed Central

    de Agustina, Beatriz; Marín, Marta María; Teti, Roberto; Rubio, Eva María

    2014-01-01

    The polishing process is the most common technology used in applications where a high level of surface quality is demanded. The automation of polishing processes is especially difficult due to the high level of skill and dexterity that is required. Much of this difficulty arises because of the lack of reliable data on the effect of the polishing parameters on the resulting surface roughness. An experimental study was developed to evaluate the surface roughness obtained during Robot Assisted Polishing processes by the analysis of acoustic emission signals in the frequency domain. The aim is to find out a trend of a feature or features calculated from the acoustic emission signals detected along the process. Such an evaluation was made with the objective of collecting valuable information for the establishment of the end point detection of polishing process. As a main conclusion, it can be affirmed that acoustic emission (AE) signals can be considered useful to monitor the polishing process state. PMID:25405509

  19. Acoustic wave device using plate modes with surface-parallel displacement

    DOEpatents

    Martin, S.J.; Ricco, A.J.

    1988-04-29

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

  20. Acoustic wave device using plate modes with surface-parallel displacement

    DOEpatents

    Martin, Stephen J.; Ricco, Antonio J.

    1992-01-01

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them.

  1. Acoustic wave device using plate modes with surface-parallel displacement

    DOEpatents

    Martin, S.J.; Ricco, A.J.

    1992-05-26

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes there between. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

  2. Acousto-Optic Interaction in Surface Acoustic Waves and Its Application to Real Time Signal Processing.

    DTIC Science & Technology

    1977-12-30

    ACOUSTO - OPTIC INTERACTION IN SURFACE ACOUSTIC WAVES AND ITS APP--ETC(U) DEC 77 0 SCHUMER, P DAS NOOOIJ -75-C-0772 NCLASSIFIED MA-ONR-30 Nt.EE E’h...CHART NAT*NAL BUREAU OF STANDARDS 1-63- ACOUSTO - OPTIC INTERACTION IN SURFACE ACOUSTIC WAVES AND ITS APPLICATION TO REAL TIME SIGNAL PROCESSING By 00 D... Acousto - optics , Integrated optics, Optical Signal Processing. 20. AbSKTRACT (Continue an reverse side it neceary and idewnt& by block mum ber) The

  3. Adjustable, rapidly switching microfluidic gradient generation using focused travelling surface acoustic waves

    SciTech Connect

    Destgeer, Ghulam; Im, Sunghyuk; Hang Ha, Byung; Ho Jung, Jin; Ahmad Ansari, Mubashshir; Jin Sung, Hyung

    2014-01-13

    We demonstrate a simple device to generate chemical concentration gradients in a microfluidic channel using focused travelling surface acoustic waves (F-TSAW). A pair of curved interdigitated metal electrodes deposited on the surface of a piezoelectric (LiNbO{sub 3}) substrate disseminate high frequency sound waves when actuated by an alternating current source. The F-TSAW produces chaotic acoustic streaming flow upon its interaction with the fluid inside a microfluidic channel, which mixes confluent streams of chemicals in a controlled fashion for an adjustable and rapidly switching gradient generation.

  4. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves.

    PubMed

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J R; Krenner, Hubert J; Wixforth, Achim; Salditt, Tim

    2014-10-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length).

  5. Adjustable, rapidly switching microfluidic gradient generation using focused travelling surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Destgeer, Ghulam; Im, Sunghyuk; Hang Ha, Byung; Ho Jung, Jin; Ahmad Ansari, Mubashshir; Jin Sung, Hyung

    2014-01-01

    We demonstrate a simple device to generate chemical concentration gradients in a microfluidic channel using focused travelling surface acoustic waves (F-TSAW). A pair of curved interdigitated metal electrodes deposited on the surface of a piezoelectric (LiNbO3) substrate disseminate high frequency sound waves when actuated by an alternating current source. The F-TSAW produces chaotic acoustic streaming flow upon its interaction with the fluid inside a microfluidic channel, which mixes confluent streams of chemicals in a controlled fashion for an adjustable and rapidly switching gradient generation.

  6. Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

    NASA Technical Reports Server (NTRS)

    Hines, Jacqueline H. (Inventor)

    2015-01-01

    A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

  7. Nonreciprocal propagation of surface acoustic wave in Ni/LiNbO 3

    NASA Astrophysics Data System (ADS)

    Sasaki, R.; Nii, Y.; Iguchi, Y.; Onose, Y.

    2017-01-01

    We investigated surface acoustic wave propagation in a Ni/LiNbO3 hybrid device. We found that the absorption and phase velocity are dependent on the sign of the wave vector, which indicates that the surface acoustic wave propagation has nonreciprocal characteristics induced by simultaneous breaking of time-reversal and spatial inversion symmetries. The nonreciprocity was reversed by 180∘ rotation of the magnetic field. The origin of the nonreciprocity is ascribed to interference of shear-type and longitudinal-type magnetoelastic couplings.

  8. Differentiation of red wines using an electronic nose based on surface acoustic wave devices.

    PubMed

    García, M; Fernández, M J; Fontecha, J L; Lozano, J; Santos, J P; Aleixandre, M; Sayago, I; Gutiérrez, J; Horrillo, M C

    2006-02-15

    An electronic nose, utilizing the principle of surface acoustic waves (SAW), was used to differentiate among different wines of the same variety of grapes which come from the same cellar. The electronic nose is based on eight surface acoustic wave sensors, one is a reference sensor and the others are coated by different polymers by spray coating technique. Data analysis was performed by two pattern recognition methods; principal component analysis (PCA) and probabilistic neuronal network (PNN). The results showed that electronic nose was able to identify the tested wines.

  9. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves

    PubMed Central

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schülein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

    2014-01-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length). PMID:25294979

  10. An instrument for low- and variable-temperature millimeter-wave surface impedance measurements under magnetic fields

    NASA Astrophysics Data System (ADS)

    Hanaguri, Tetsuo; Takaki, Keishi; Tsuchiya, Yoshishige; Maeda, Atsutaka

    2003-10-01

    We describe a low-temperature millimeter-wave (44 GHz) surface impedance measurement instrument based on the cavity perturbation method. In this instrument, all millimeter-wave paths at low temperatures (including the cavity resonator), are located inside a high vacuum tube, which can be inserted into a 7 T superconducting magnet. This design, which is free of exchange gas, enables measurements over a wide temperature range as well as providing stable and reproducible operation. By pumping a 3He pot attached to a cavity, a sample can be cooled well below 1 K. We present experimental results which demonstrate the performance of the instrument.

  11. Acoustics and hydrodynamics of a drop impact on a water surface

    NASA Astrophysics Data System (ADS)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2017-01-01

    Hydrodynamic and acoustic processes associated with a drop impact on a water surface were studied experimentally. Acoustic signals were detected underwater (with a hydrophone) and in air (with a microphone), the flow pattern was recorded with a high-speed camera, and the surface perturbation was monitored with a laser detector. The dimensionless parameters of flows (Reynolds, Froude, and Weber numbers) induced by the impact varied with fall height within the ranges of 5000 < Re < 20000, 20 < Fr < 350, and 70 < We < 1000. The sequence of acoustic signals incorporated an impact pulse at the moment of contact between a drop and the surface and a series of acoustic packets attributable to the resonance emission of gas cavities. The top of the impact pulse, which was detected clearly in the entire fall height range, had a complex structure with short high-frequency and longer low-frequency oscillations. The total number and the parameters of emitted acoustic packets depended to a considerable extent on the fall height. The cases of lacking, one-time, and repeated emission of packets were noted in a series of experiments performed at a constant fall height. The analysis of video data showed that the signal variability was induced by considerable differences in the scenarios of water entry of a drop, which assumed an ovoid shape at the end trajectory segment, in the mentioned experiments.

  12. A wideband characterization of the acoustic spreading function in the surface layer of the atmosphere

    NASA Astrophysics Data System (ADS)

    Mahon, Mark P.

    2001-07-01

    Acoustic signals propagating in the surface layer (within 100 meters of the earth's surface) of the atmosphere are subjected to refraction and scattering off of turbulent pockets of air, known as eddies. These eddies are postulated to be of varying size with a length-scale directly proportional to the height above the surface and are inherently stochastic. The net effect is a fundamentally dispersive process imparting frequency dependent amplitude and phase variations on the propagating signals. Mathematically, this can be characterized by a spreading function. In addition to the atmospheric effects the acoustic channel will typically possess multiple deterministic propagation paths. In this thesis original experimental work designed to characterize, in a wideband sense, the surface layer spreading function is presented. This is accomplished by analyzing the acoustic channel using communications theory typically employed in the electromagnetic environment. Small- and large-scale acoustic channel fluctuations are characterized simultaneously through signal set design and advanced space-time signal processing techniques. Carefully designed wideband (spread spectrum) signals were used to probe and interact with the channel to provide a mechanism to bound the relevant parameters and classify the type of time and frequency dispersive fading effects. The experimental results demonstrate that the signal design methodology employed facilitates simultaneous parameterization of the time-varying surface layer structures (turbulence) over a spread of time-scales. The signals were collected by an acoustic planar array located approximately 750 meters from the source location. Direction-of-arrival techniques were applied to track the multiple arrival angles over time. This provided a means of tracking the refraction effects imparted onto the acoustic signal by the turbulent atmosphere and discriminating other arrival angles due to ground waves and deterministic paths. The signal

  13. Surface-acoustic-wave device incorporating conducting Langmuir-Blodgett films

    NASA Astrophysics Data System (ADS)

    Holcroft, B.; Roberts, G. G.; Barraud, A.; Richard, J.

    1987-04-01

    Surface-acoustic-wave devices incorporating conducting Langmuir-Blodgett films are reported for the first time. Excellent characteristics have been obtained using a mixed valence charge transfer salt of a substituted pyridinium tetracyanoquinodimethane. The control afforded by the deposition technique has enabled the fractional change in surface wave velocity due to the electrical effects to be distinguished from those due to mass loading. The resistivity of the organic surface layer is measured to be 2 ohm-cm.

  14. Impedance analysis of acupuncture points and pathways

    NASA Astrophysics Data System (ADS)

    Teplan, Michal; Kukučka, Marek; Ondrejkovičová, Alena

    2011-12-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  15. Separation of biological cells in a microfluidic device using surface acoustic waves (SAWs)

    NASA Astrophysics Data System (ADS)

    Ai, Ye; Marrone, Babetta L.

    2014-03-01

    In this study, a surface acoustic wave (SAW)-based microfluidic device has been developed to separate heterogeneous particle or cell mixtures in a continuous flow using acoustophoresis. The microfluidic device is comprised of two components, a SAW transducer and a microfluidic channel made of polydimethylsiloxane (PDMS). The SAW transducer was fabricated by patterning two pairs of interdigital electrodes on a lithium niobate (LiNbO3) piezoelectric substrate. When exciting the SAW transducer by AC signals, a standing SAW is generated along the cross-section of the channel. Solid particles immersed in the standing SAW field are accordingly pushed to the pressure node arising from the acoustic radiation force acting on the particles, referring to the acoustic particle-focusing phenomenon. Acoustic radiation force highly depends on the particle properties, resulting in different acoustic responses for different types of cells. A numerical model, coupling the piezoelectric effect in the solid substrate and acoustic pressure in the fluid, was developed to provide a better understanding of SAW-based particle manipulation. Separation of two types of fluorescent particles has been demonstrated using the developed SAW-based microfluidic device. An efficient separation of E. coli bacteria from peripheral blood mononuclear cell (PBMC) samples has also been successfully achieved. The purity of separated E. coli bacteria and separated PBMCs were over 95% and 91%, respectively, obtained by a flow cytometric analysis. The developed microfluidic device can efficiently separate E. coli bacteria from biological samples, which has potential applications in biomedical analysis and clinical diagnosis.

  16. Resonant attenuation of surface acoustic waves by a disordered monolayer of microspheres

    NASA Astrophysics Data System (ADS)

    Eliason, J. K.; Vega-Flick, A.; Hiraiwa, M.; Khanolkar, A.; Gan, T.; Boechler, N.; Fang, N.; Nelson, K. A.; Maznev, A. A.

    2016-02-01

    Attenuation of surface acoustic waves (SAWs) by a disordered monolayer of polystyrene microspheres is investigated. Surface acoustic wave packets are generated by a pair of crossed laser pulses in a glass substrate coated with a thin aluminum film and detected via the diffraction of a probe laser beam. When a 170 μm-wide strip of micron-sized spheres is placed on the substrate between the excitation and detection spots, strong resonant attenuation of SAWs near 240 MHz is observed. The attenuation is caused by the interaction of SAWs with a contact resonance of the microspheres, as confirmed by acoustic dispersion measurements on the microsphere-coated area. Frequency-selective attenuation of SAWs by such a locally resonant metamaterial may lead to reconfigurable SAW devices and sensors, which can be easily manufactured via self-assembly techniques.

  17. Evaluation of near-surface stress distributions in dissimilar welded joint by scanning acoustic microscopy.

    PubMed

    Kwak, Dong Ryul; Yoshida, Sanichiro; Sasaki, Tomohiro; Todd, Judith A; Park, Ik Keun

    2016-04-01

    This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints.

  18. Piezoelectric surface acoustical phonon amplification in graphene on a GaAs substrate

    SciTech Connect

    Nunes, O. A. C.

    2014-06-21

    We study the interaction of Dirac Fermions in monolayer graphene on a GaAs substrate in an applied electric field by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (piezoelectric acoustical (PA)) and of the intrinsic deformation potential of acoustical phonons in graphene (deformation acoustical (DA)). We find that provided the dc field exceeds a threshold value, emission of piezoelectric (PA) and deformation (DA) acoustical phonons can be obtained in a wide frequency range up to terahertz at low and high temperatures. We found that the phonon amplification rate R{sup PA,DA} scales with T{sub BG}{sup S−1} (S=PA,DA), T{sub BG}{sup S} being the Block−Gru{sup ¨}neisen temperature. In the high-T Block−Gru{sup ¨}neisen regime, extrinsic PA phonon scattering is suppressed by intrinsic DA phonon scattering, where the ratio R{sup PA}/R{sup DA} scales with ≈1/√(n), n being the carrier concentration. We found that only for carrier concentration n≤10{sup 10}cm{sup −2}, R{sup PA}/R{sup DA}>1. In the low-T Block−Gru{sup ¨}neisen regime, and for n=10{sup 10}cm{sup −2}, the ratio R{sup PA}/R{sup DA} scales with T{sub BG}{sup DA}/T{sub BG}{sup PA}≈7.5 and R{sup PA}/R{sup DA}>1. In this regime, PA phonon dominates the electron scattering and R{sup PA}/R{sup DA}<1 otherwise. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as an acoustical phonon amplifier and a frequency-tunable acoustical phonon device.

  19. Acoustofluidics and whole-blood manipulation in surface acoustic wave counterflow devices.

    PubMed

    Travagliati, Marco; Shilton, Richie J; Pagliazzi, Marco; Tonazzini, Ilaria; Beltram, Fabio; Cecchini, Marco

    2014-11-04

    On-chip functional blocks for sample preprocessing are necessary elements for the implementation of fully portable micrototal analysis systems (μTAS). We demonstrate and characterize the microparticle and whole-blood manipulation capabilities of surface acoustic wave (SAW) driven counterflow micropumps. The motion of suspended cells in this system is governed by the two dominant acoustic forces associated with the scattered SAW (of wavelength λf): acoustic-radiation force and acoustic-streaming Stokesian drag force. We show that by reducing the microchannel height (h) beyond a threshold value the balance of these forces is shifted toward the acoustic-radiation force and that this yields control of two different regimes of microparticle dynamics. In the regime dominated by the acoustic radiation force (h ≲ λf), microparticles are collected in the seminodes of the partial standing sound-wave arising from reflections off microchannel walls. This enables the complete separation of plasma and corpuscular components of whole blood in periodical predetermined positions without any prior sample dilution. Conversely, in the regime dominated by acoustic streaming (h ≫ λf), the microbeads follow vortical streamlines in a pattern characterized by three different phases during microchannel filling. This makes it possible to generate a cell-concentration gradient within whole-blood samples, a behavior not previously reported in any acoustic-streaming device. By careful device design, a new class of SAW pumping devices is presented that allows the manipulation and pretreatment of whole-blood samples for portable and integrable biological chips and is compatible with hand-held battery-operated devices.

  20. Frequency effect on streaming phenomenon induced by Rayleigh surface acoustic wave in microdroplets

    NASA Astrophysics Data System (ADS)

    Alghane, M.; Fu, Y. Q.; Chen, B. X.; Li, Y.; Desmulliez, M. P. Y.; Walton, A. J.

    2012-10-01

    Acoustic streaming of ink particles inside a water microdroplet generated by a surface acoustic wave (SAW) has been studied numerically using a finite volume numerical method and these results have been verified using experimental measurements. Effects of SAW excitation frequency, droplet volume, and radio-frequency (RF) power are investigated, and it has been shown that SAW excitation frequency influences the SAW attenuation length, lSAW, and hence the acoustic energy absorbed by liquid. It has also been observed that an increase of excitation frequency generally enhances the SAW streaming behavior. However, when the frequency exceeds a critical value that depends on the RF power applied to the SAW device, weaker acoustic streaming is observed resulting in less effective acoustic mixing inside the droplet. This critical value is characterised by a dimensionless ratio of droplet radius to SAW attenuation length, i.e., Rd/lSAW. With a mean value of Rd/lSAW ≈ 1, a fast and efficient mixing can be induced, even at the lowest RF power of 0.05 mW studied in this paper. On the other hand, for the Rd/lSAW ratios much larger than ˜1, significant decreases in streaming velocities were observed, resulting in a transition from regular (strong) to irregular (weak) mixing/flow. This is attributed to an increased absorption rate of acoustic wave energy that leaks into the liquid, resulting in a reduction of the acoustic energy radiated away from the SAW interaction region towards the droplet free surface. It has been demonstrated in this study that a fast and efficient mixing process with a smaller RF power could be achieved if the ratio of Rd/lSAW ≤ 1 in the SAW-droplet based microfluidics.

  1. Acoustic techniques for studying soil-surface seals and crusts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of raindrops on a soil surface during a rainstorm may cause soil-surface sealing and upon drying, soil crusting. Soil-surface sealing is a result of the clogging of interaggregate pores by smaller suspended particles in the water and by structural deformation of the soil fabric, which red...

  2. Finite element analysis of true and pseudo surface acoustic waves in one-dimensional phononic crystals

    SciTech Connect

    Graczykowski, B. Alzina, F.; Gomis-Bresco, J.; Sotomayor Torres, C. M.

    2016-01-14

    In this paper, we report a theoretical investigation of surface acoustic waves propagating in one-dimensional phononic crystal. Using finite element method eigenfrequency and frequency response studies, we develop two model geometries suitable to distinguish true and pseudo (or leaky) surface acoustic waves and determine their propagation through finite size phononic crystals, respectively. The novelty of the first model comes from the application of a surface-like criterion and, additionally, functional damping domain. Exemplary calculated band diagrams show sorted branches of true and pseudo surface acoustic waves and their quantified surface confinement. The second model gives a complementary study of transmission, reflection, and surface-to-bulk losses of Rayleigh surface waves in the case of a phononic crystal with a finite number of periods. Here, we demonstrate that a non-zero transmission within non-radiative band gaps can be carried via leaky modes originating from the coupling of local resonances with propagating waves in the substrate. Finally, we show that the transmission, reflection, and surface-to-bulk losses can be effectively optimised by tuning the geometrical properties of a stripe.

  3. The spatially dispersive eigenvalues of permittivity operator and frequency-dependent surface impedance for conductors without the dc dissipation

    NASA Astrophysics Data System (ADS)

    Dresvyannikov, M. A.; Chernyaev, A. P.; Karuzskii, A. L.; Mityagin, Yu. A.; Perestoronin, A. V.; Volchkov, N. A.

    2016-12-01

    An operator of the permittivity can completely describe alone a microwave response of conductors with the spatial dispersion. An eigenvalue problem for the nonself-adjoint permittivity operator Ễa was considered generally to search the wave solutions for conductors and superconductors. An appearance of additional solutions (additional waves) due to the spatial dispersion can strongly influence the properties of nanoelectronic devices or novel superconducting materials in the form of anomalous losses for example, and should be accounted in simulation and modeling of micro- and nanoelectronic devices. It was concluded that the modulus |Ž| of the surface impedance is proportional to the degree of frequency ω2/3 for all normal conductor solutions except that for the superconductor. There was some criticism related to the idea that the electrodynamics of superconductors should be in principle reduced to those for conductors as the temperature approaches and beyond the critical temperature. We demonstrate that appropriately taken into account effects of the spatial dispersion can give the general frequency dependence of the surface impedance for the obtained solutions including that for the superconductor. It is shown that an incorporation of the spatial dispersion leads to an appearance of the Meissner effect in perfect conductors in the same manner as in superconductors.

  4. Transporting and manipulating single electrons in surface-acoustic-wave minima

    NASA Astrophysics Data System (ADS)

    Ford, Christopher J. B.

    2017-03-01

    A surface acoustic wave (SAW) can produce a moving potential wave that can trap and drag electrons along with it. We review work on using a SAW to create moving quantum dots containing single electrons, with the aims of developing a current standard, emitting single photons, transferring single electrons between static quantum dots, and investigating non-adiabatic effects.

  5. Characterization Test Report for the Mnemonics-UCS Wireless Surface Acoustic Wave Sensor System

    NASA Technical Reports Server (NTRS)

    Duncan, Joshua J.; Youngquist, Robert C.

    2013-01-01

    The scope of this testing includes the Surface Acoustic Wave Sensor System delivered to KSC: two interrogator (transceiver) systems, four temperature sensors, with wooden mounting blocks, two antennas, two power supplies, network cables, and analysis software. Also included are a number of additional temperature sensors and newly-developed hydrogen sensors

  6. Surface acoustic wave generation and detection using graphene interdigitated transducers on lithium niobate

    SciTech Connect

    Mayorov, A. S.; Hunter, N.; Muchenje, W.; Wood, C. D.; Rosamond, M.; Linfield, E. H.; Davies, A. G.; Cunningham, J. E.

    2014-02-24

    We demonstrate the feasibility of using graphene as a conductive electrode for the generation and detection of surface acoustic waves at 100 s of MHz on a lithium niobate substrate. The graphene interdigitated transducers (IDTs) show sensitivity to doping and temperature, and the characteristics of the IDTs are discussed in the context of a lossy transmission line model.

  7. Acoustic Receptivity of a Blasius Boundary Layer with 2-D and Oblique Surface Waviness

    NASA Technical Reports Server (NTRS)

    King, Rudolph A.; Breuer, Kenneth S.

    2000-01-01

    An experimental investigation was conducted to examine acoustic receptivity and subsequent boundary-layer instability evolution for a Blasius boundary layer formed on a flat plate in the presence of two-dimensional (2-D) and oblique (3-D) surface waviness. The effect of the non-localized surface roughness geometry and acoustic wave amplitude on the receptivity process was explored. The surface roughness had a well defined wavenumber spectrum with fundamental wavenumber k (sub w). A planar downstream traveling acoustic wave was created to temporally excite the flow near the resonance frequency of an unstable eigenmode corresponding to k (sub ts) = k (sub w). The range of acoustic forcing levels, epsilon, and roughness heights, DELTA h, examined resulted in a linear dependence of receptivity coefficients; however, the larger values of the forcing combination epsilon dot DELTA h resulted in subsequent nonlinear development of the Tollmien-Schlichting (T-S) wave. This study provided the first experimental evidence of a marked increase in the receptivity coefficient with increasing obliqueness of the surface waviness in excellent agreement with theory. Detuning of the 2-D and oblique disturbances was investigated by varying the streamwise wall-roughness wavenumber a,, and measuring the T-S response. For the configuration where laminar-to-turbulent breakdown occurred, the breakdown process was found to be dominated by energy at the fundamental and harmonic frequencies, indicative of K-type breakdown.

  8. An all fiber-optic sensor for surface acoustic wave measurements

    NASA Technical Reports Server (NTRS)

    Bowers, J. E.; Jungerman, R. L.; Khuri-Yakub, B. T.; Kino, G. S.

    1983-01-01

    A surface acoustic wave (SAW) sensor constructed from single-mode fiber-optic components is described. An analysis of reciprocal and nonreciprocal modes of operation of the sensor is presented. Results from measurements on a variety of SAW devices illustrate the use of the sensor. The amplitude sensitivity is 0.0003 A for an integration time of 0.1 s.

  9. Effect of surface acoustic waves on the catalytic decomposition of ethanol employing a comb transducer for ultrasonic generation

    SciTech Connect

    S. J. Reese; D. H. Hurley; H.W. Rollins

    2006-04-01

    The effect of surface acoustic waves, generated on a silver catalyst using a comb transducer, on the catalytic decomposition of ethanol is examined. The comb transducer employs purely mechanical means for surface acoustic wave (SAW) transduction. Unlike interdigital SAW transducers on piezoelectric substrates, the complicating effects of heat generation due to electromechanical coupling, high electric fields between adjacent electrodes, and acoustoelectric currents are avoided. The ethanol decomposition reactions are carried out at 473 K. The rates of acetaldehyde and ethylene production are retarded when acoustic waves are applied. The rates recover to varying degrees when acoustic excitation ceases.

  10. Piezoelectric crystal impedance analysis for investigating the modification processes of protein, cross-linker, and DNA on gold surface

    NASA Astrophysics Data System (ADS)

    Zhou, Anhong; Xie, Qingji; Li, Ping; Nie, Lihua; Yao, Shouzhuo

    2000-05-01

    The processes of surface modification on gold-coated piezoelectric quartz crystal sensor have been in situ investigated by using the impedance analysis technique. The changes of equivalent circuit parameters were used to interpret the different behaviors of successively modifying protein, cross-linker, and DNA onto a gold electrode surface. It was found that the frequency changes due to protein adsorption might be described as a sum of two exponential functions, compared with a first-order kinetic function exhibited in subsequent binding of cross-linker to protein. The kinetic parameters were fitted to these two cases. It was also shown that the DNA molecules binding to cross-linker gave rise to the changes of the density-viscosity and the dielectric constant, both being linearly related to DNA concentration in the liquid when below 6.0 μg m -1.

  11. The neonatal acoustic reflex.

    PubMed

    Weatherby, L A; Bennett, M J

    1980-01-01

    Probe tones from 220 Hz to 2 000 Hz were used to measure the static and dynamic acoustic impedance of 44 neonates. Acoustic reflex thresholds to broad band noise were obtained from every neonate tested when employing the higher frequency probe tones. The reflex threshold levels measured are similar to those of adults. The static impedance values are discussed to give a possible explanation of why reflex thresholds cannot be detected using conventional 220 Hz impedance bridges.

  12. Acoustical properties of highly porous fibrous materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1979-01-01

    Highly porous, fibrous bulk sound absorbing materials are studied with a view toward understanding their acoustical properties and performance in a wide variety of applications including liners of flow ducts. The basis and criteria for decoupling of acoustic waves in the pores of the frame and compressional waves in the frame structure are established. The equations of motion are recast in a form that elucidates the coupling mechanisms. The normal incidence surface impedance and absorption coefficient of two types of Kevlar 29 and an open celled foam material are studied. Experimental values and theoretical results are brought into agreement when the structure factor is selected to provide a fit to the experimental data. A parametric procedure for achieving that fit is established. Both a bulk material quality factor and a high frequency impedance level are required to characterize the real and imaginary part of the surface impedance and absorption coefficient. A derivation of the concepts of equivalent density and dynamic resistance is presented.

  13. Integrated microfluidics system using surface acoustic wave and electrowetting on dielectrics technology.

    PubMed

    Li, Y; Fu, Y Q; Brodie, S D; Alghane, M; Walton, A J

    2012-03-01

    This paper presents integrated microfluidic lab-on-a-chip technology combining surface acoustic wave (SAW) and electro-wetting on dielectric (EWOD). This combination has been designed to provide enhanced microfluidic functionality and the integrated devices have been fabricated using a single mask lithographic process. The integrated technology uses EWOD to guide and precisely position microdroplets which can then be actuated by SAW devices for particle concentration, acoustic streaming, mixing and ejection, as well as for sensing using a shear-horizontal wave SAW device. A SAW induced force has also been employed to enhance the EWOD droplet splitting function.

  14. Broadband convergence of acoustic energy with binary reflected phases on planar surface

    NASA Astrophysics Data System (ADS)

    Fan, Xu-Dong; Zhu, Yi-Fan; Liang, Bin; Yang, Jing; Cheng, Jian-Chun

    2016-12-01

    We propose to produce efficient three-dimensional sound converging in broadband with binary reflected phases on a planar surface with unit cells consisting of only two kinds of elements. The mechanism is experimentally demonstrated by focusing airborne sound and by forming an "acoustic needle," with handmade arrays of commercial test tubes with/without lids. Both the simulated and measured results show the precise control of converging acoustic energy despite misalignment errors obvious even to naked eyes. Our approach with extreme simplicity yet good robustness may apply in various scenarios that conventionally need complicated elements and continuous variation of parameters for focusing sound.

  15. Optical Generation And Spatially Distinct Interferometric Detection Of Ultrahigh Frequency Surface Acoustic Waves

    SciTech Connect

    David H. Hurley

    2006-05-01

    Generation and interferometric detection of 22 GHz surface acoustic waves (SAWs) using two laterally separated absorption gratings on a Si substrate are presented. Optical phase sensitive detection of SAWs is demonstrated using a modified Sagnac interferometer. The reflection characteristics of the suboptical wavelength grating necessitate the use of only linear polarization. This is accomplished by employing a Faraday rotator to ensure path reversal of the reference and signal pulses. The enhanced sensitivity of the interferometer is exploited to measure the acoustic disturbance on an identical absorption grating at a distance of ~4.5 µm from the generation site.

  16. Wireless surface acoustic wave sensors for displacement and crack monitoring in concrete structures

    NASA Astrophysics Data System (ADS)

    Perry, M.; McKeeman, I.; Saafi, M.; Niewczas, P.

    2016-03-01

    In this work, we demonstrate that wireless surface acoustic wave devices can be used to monitor millimetre displacements in crack opening during the cyclic and static loading of reinforced concrete structures. Sensors were packaged to extend their gauge length and to protect them against brittle fracture, before being surface-mounted onto the tensioned surface of a concrete beam. The accuracy of measurements was verified using computational methods and optical-fibre strain sensors. After packaging, the displacement and temperature resolutions of the surface acoustic wave sensors were 10 μ {{m}} and 2 °C respectively. With some further work, these devices could be retrofitted to existing concrete structures to facilitate wireless structural health monitoring.

  17. Effects of Liner Length and Attenuation on NASA Langley Impedance Eduction

    NASA Technical Reports Server (NTRS)

    Jones, M. G.; Watson, W. R.

    2016-01-01

    This study explores the effects of liner length and attenuation on the CHE (convected Helmholtz equation) impedance eduction method, in which the surface impedance of an acoustic liner is inferred through an iterative process based on repeated solutions to the convected Helmholtz equation. Wire mesh-over-honeycomb and perforate-over-honeycomb acoustic liners are tested in the NASA Langley Grazing Flow Impedance Tube, and the resultant data are processed using two impedance eduction methods. The first is the CHE method, and the second is a direct method (labeled the KT method) that uses the Kumaresan and Tufts algorithm to compute the impedance directly. The CHE method has been extensively used for acoustic liner evaluation, but experiences anomalous behavior under some test conditions. It is postulated that the anomalies are related to the liner length and/or attenuation. Since the KT method only employs data measured over the length of the liner, it is expected to be unaffected by liner length. A comparison of results achieved with the two impedance eduction methods is used to explore the interactive effects of liner length and attenuation on the CHE impedance eduction method.

  18. The Impact of Very High Frequency Surface Reverberation on Coherent Acoustic Propagation and Modeling

    DTIC Science & Technology

    2015-09-30

    range of wind -driven conditions. The model will focus on signal coherence, and second-order amplitude and Doppler statistics. A second long-term goal...surface scattering in the literature are rare. The physics of very high frequency (VHF) scattering is expected to be strongly dependent on wind speed...Doppler and coherence of VHF acoustic signals scattered from a rough ocean surface driven by a range of wind speeds. The second is to investigate the

  19. Surface acoustic admittance and absorption of highly porous, layered, fibrous materials

    NASA Astrophysics Data System (ADS)

    Tesar, J. S.; Lambert, R. F.

    1984-06-01

    Some acoustic properties of Kevlar-29 - a fine fibered, layered material is investigated. Kevlar is characterized by very high strength, uniform filaments arranged in a parallel batt where most filaments are random in the x-y plane but ordered as planes in the z direction. For experimental purposes, volume porosity, static flow resistance and mean filament diameter are used to identify the material. To determine the acoustic surface admittance of Kevlar, batts of the material are cut into small pads and placed into a standing wave tube terminated by a rigid brass plug. The attenuation and relative phase shift are recorded at each frequency in the range of 50 to 6000 Hz. Normalized conductance and susceptance are combined to form the acoustic absorption coefficient. The data are compared with theory by plotting the normalized admittance and normal incident absorption coefficient versus cyclic frequency.

  20. Interaction of surface and bulk acoustic waves with a two-dimensional semimetal

    SciTech Connect

    Kovalev, V. M. Chaplik, A. V.

    2015-02-15

    The interaction of a surface elastic Rayleigh wave with an electron-hole plasma in a two-dimensional semimetal has been theoretically studied as determined by the deformation potential and piezoelectric mechanisms. Dispersion equations describing the coupled plasmon-acoustic modes for both types of interaction are derived, and damping of the Rayleigh wave is calculated. The damping of the acoustic and optical plasmon modes, which is related to the sound emission by plasma oscillations into the substrate volume, is calculated and it is shown that this sound emission is predominantly determined by the acoustic plasmon mode in the case of a deformation potential mechanism and by the optical mode in the case of a piezoelectric mechanism.

  1. Surface acoustic admittance and absorption of highly porous, layered, fibrous materials

    NASA Technical Reports Server (NTRS)

    Tesar, J. S.; Lambert, R. F.

    1984-01-01

    Some acoustic properties of Kevlar-29 - a fine fibered, layered material is investigated. Kevlar is characterized by very high strength, uniform filaments arranged in a parallel batt where most filaments are random in the x-y plane but ordered as planes in the z direction. For experimental purposes, volume porosity, static flow resistance and mean filament diameter are used to identify the material. To determine the acoustic surface admittance of Kevlar, batts of the material are cut into small pads and placed into a standing wave tube terminated by a rigid brass plug. The attenuation and relative phase shift are recorded at each frequency in the range of 50 to 6000 Hz. Normalized conductance and susceptance are combined to form the acoustic absorption coefficient. The data are compared with theory by plotting the normalized admittance and normal incident absorption coefficient versus cyclic frequency.

  2. Computation of acoustic absorption in media composed of packed microtubes exhibiting surface irregularity.

    PubMed

    Kulpe, Jason A; Lee, Chang-Yong; Leamy, Michael J

    2011-08-01

    A multi-scale homogenization technique and a finite element-based solution procedure are employed to compute acoustic absorption in smooth and rough packed microtubes. The absorption considered arises from thermo-viscous interactions between the fluid media and the microtube walls. The homogenization technique requires geometric periodicity, which for smooth tubes is invoked using the periodicity of the finite element mesh; for rough microtubes, the periodicity invoked is that associated with the roughness. Analysis of the packed configurations, for the specific microtube radii considered, demonstrates that surface roughness does not appreciably increase the overall absorption, but instead shifts the peaks and values of the absorption curve. Additionally, the effect of the fluid media temperature on acoustic absorption is also explored. The results of the investigation are used to make conclusions about tailored design of acoustically absorbing microtube-based materials.

  3. Direct visualization of surface acoustic waves along substrates using smoke particles

    NASA Astrophysics Data System (ADS)

    Tan, Ming K.; Friend, James R.; Yeo, Leslie Y.

    2007-11-01

    Smoke particles (SPs) are used to directly visualize surface acoustic waves (SAWs) propagating on a 128°-rotated Y-cut X-propagating lithium niobate (LiNbO3) substrate. By electrically exciting a SAW device in a compartment filled with SP, the SP were found to collect along the regions where the SAW propagates on the substrate. The results of the experiments show that SPs are deposited adjacent to regions of large vibration amplitude and form a clear pattern corresponding to the surface wave profile on the substrate. Through an analysis of the SAW-induced acoustic streaming in the air adjacent to the substrate and the surface acceleration measured with a laser Doppler vibrometer, we postulate that the large transverse surface accelerations due to the SAW ejects SP from the surface and carries them aloft to relatively quiescent regions nearby via acoustic streaming. Offering finer detail than fine powders common in Chladni figures [E. Chladni, Entdeckungen über die Theorie des Klanges (Weidmanns, Erben und Reich, Leipzig, Germany, 1787)] the approach is an inexpensive and a quick counterpart to laser interferometric techniques, presenting a means to explore the controversial phenomena of particle agglomeration on surfaces.

  4. Virtual membrane for filtration of particles using surface acoustic waves (SAW).

    PubMed

    Fakhfouri, Armaghan; Devendran, Citsabehsan; Collins, David J; Ai, Ye; Neild, Adrian

    2016-09-21

    Surface acoustic wave (SAW) based particle manipulation is contactless, versatile, non-invasive and biocompatible making it useful for biological studies and diagnostic technologies. In this work, we present a sensitive particle sorting system, termed the virtual membrane, in which a periodic acoustic field with a wavelength on the order of particle dimensions permits size-selective filtration. Polystyrene particles that are larger than approximately 0.3 times the acoustic half-wavelength experience a force repelling them from the acoustic field. If the particle size is such that, at a given acoustic power and flow velocity, this repulsive force is dominant over the drag force, these particles will be prohibited from progressing further downstream (i.e. filtered), while smaller particles will be able to pass through the force field along the pressure nodes (akin to a filter's pores). Using this mechanism, we demonstrate high size selectivity using a standing SAW generated by opposing sets of focused interdigital transducers (FIDTs). The use of FIDTs permits the generation of a highly localized standing wave field, here used for filtration in μl min(-1) order flow rates at 10s of mW of applied power. Specifically, we demonstrate the filtration of 8 μm particles from 5 μm particles and 10.36 μm particles from 7.0 μm and 5.0 μm particles, using high frequency SAW at 258 MHz, 192.5 MHz, and 129.5 MHz, respectively.

  5. A high-throughput standing surface acoustic wave (SSAW)-based cell sorter

    PubMed Central

    Li, Peng; Mao, Zhangming; Huang, Po-Hsun; Rufo, Joseph; Guo, Feng; Wang, Lin; McCoy, J. Philip; Levine, Stewart J.; Huang, Tony Jun

    2015-01-01

    Acoustic-based fluorescence activated cell sorters (FACS) have drawn increased attention in recent years due to their versatility, high biocompatibility, high controllability, and simple design. However, the sorting throughput for existing acoustic cell sorters is far from optimum for practical applications. Here we report a high-throughput cell sorting method based on standing surface acoustic waves (SSAWs). We utilized a pair of focused interdigital transducers (FIDTs) to generate SSAW with high resolution and high energy efficiency. As a result, the sorting throughput is improved significantly from conventional acoustic-based cell sorting methods. We demonstrated the successful sorting of 10 μm polystyrene particles with a minimum actuation time of 72 μs, which translates to a potential sorting rate of more than 13,800 events/s. Without using a cell-detection unit, we were able to demonstrate an actual sorting throughput of 3,300 events/s. Our sorting method can be conveniently integrated with upstream detection units, and it represents an important development towards a functional acoustic-based FACS system. PMID:26289231

  6. Investigation of acoustic emission and surface treatment to improve tool materials and metal forming process

    NASA Astrophysics Data System (ADS)

    Cao, Deming

    Silicon nitride and WC-Co cermet tools are used for metal forming processes including extrusion and drawing. These materials are used to make tool dies which are exposed to deformation caused by friction and wear. Surface treatments such as ion implantation, laser blazing and coating have been found to improve surface properties, to optimize tribological behavior between the metal and die, as well as to extend service life of the tool dies. Early detection and continuous monitoring processes by non destructive testing (NDT) methods are needed in order to ensure the functionality of the wear process and extend the tool service life. Acoustic emission is one of the promising NDT methods for this application. The surface treatment chosen for this investigation was ion implantation. Three types of wear resistant materials with and without surface treatment were selected for this project; silicon nitride and two tungsten carbides (6% Cobalt and 10% Cobalt). This investigation was conducted using a pin-on-disk device for wear/friction tests of the selected materials with lubrication and/or without lubrication against both a stainless steel disk and an aluminum disk. The acoustic emissions generated during the experiments were recorded and analyzed. The results of this investigation showed that the ion implantation improved the tribological properties of the materials and reduced acoustic emission and coefficient of friction. A linear relationship between the average amplitude of the acoustic emission and the coefficient of friction of the tested materials was found. The investigation demonstrated that the acoustic emission method could be used to monitor the wear/friction processes.

  7. Relating surface roughness and magnetic domain structure to giant magneto-impedance of Co-rich melt-extracted microwires

    PubMed Central

    Jiang, S. D.; Eggers, T.; Thiabgoh, O.; Xing, D. W.; Fei, W. D.; Shen, H. X.; Liu, J. S.; Zhang, J. R.; Fang, W. B.; Sun, J. F.; Srikanth, H.; Phan, M. H.

    2017-01-01

    Understanding the relationship between the surface conditions and giant magneto-impedance (GMI) in Co-rich melt-extracted microwires is key to optimizing their magnetic responses for magnetic sensor applications. The surface magnetic domain structure (SMDS) parameters of ~45 μm diameter Co69.25Fe4.25Si13B13.5-xZrx (x = 0, 1, 2, 3) microwires, including the magnetic domain period (d) and surface roughness (Rq) as extracted from the magnetic force microscopy (MFM) images, have been correlated with GMI in the range 1–1000 MHz. It was found that substitution of B with 1 at. % Zr increased d of the base alloy from 729 to 740 nm while retaining Rq from ~1 nm to ~3 nm. A tremendous impact on the GMI ratio was found, increasing the ratio from ~360% to ~490% at an operating frequency of 40 MHz. Further substitution with Zr decreased the high frequency GMI ratio, which can be understood by the significant increase in surface roughness evident by force microscopy. This study demonstrates the application of the domain period and surface roughness found by force microscopy to the interpretation of the GMI in Co-rich microwires.

  8. Transonic flight flutter tests of a control surface utilizing an impedance response technique

    NASA Technical Reports Server (NTRS)

    Mirowitz, L. I.

    1975-01-01

    Transonic flight flutter tests of the XF3H-1 Demon Airplane were conducted utilizing a frequency response technique in which the oscillating rudder provides the means of system excitation. These tests were conducted as a result of a rudder flutter incident in the transonic speed range. The technique employed is presented including a brief theoretical development of basic concepts. Test data obtained during the flight are included and the method of interpretation of these data is indicated. This method is based on an impedance matching technique. It is shown that an artificial stabilizing device, such as a damper, may be incorporated in the system for test purposes without complicating the interpretation of the test results of the normal configuration. Data are presented which define the margin of stability introduced to the originally unstable rudder by design changes which involve higher control system stiffness and external damper. It is concluded that this technique of flight flutter testing is a feasible means of obtaining flutter stability information in flight.

  9. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    SciTech Connect

    Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping

    2015-05-15

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  10. Laser photoacoustic technique for ultrasonic surface acoustic wave velocity evaluation on porcelain

    NASA Astrophysics Data System (ADS)

    Qian, K.; Tu, S. J.; Gao, L.; Xu, J.; Li, S. D.; Yu, W. C.; Liao, H. H.

    2016-10-01

    A laser photoacoustic technique has been developed to evaluate the surface acoustic wave (SAW) velocity of porcelain. A Q-switched Nd:YAG laser at 1064 nm was focused by a cylindrical lens to initiate broadband SAW impulses, which were detected by an optical fiber interferometer with high spatial resolution. Multiple near-field surface acoustic waves were observed on the sample surface at various locations along the axis perpendicular to the laser line source as the detector moved away from the source in the same increments. The frequency spectrum and dispersion curves were obtained by operating on the recorded waveforms with cross-correlation and FFT. The SAW phase velocities of the porcelain of the same source are similar while they are different from those of different sources. The marked differences of Rayleigh phase velocities in our experiment suggest that this technique has the potential for porcelain identification.

  11. Excitation and propagation of shear-horizontal-type surface and bulk acoustic waves.

    PubMed

    Hashimoto, K Y; Yamaguchi, M

    2001-09-01

    This paper reviews the basic properties of shear-horizontal (SH)-type surface acoustic waves (SAWs) and bulk acoustic waves (BAWs). As one of the simplest cases, the structure supporting Bleustein-Gulyaev-Shimizu waves is considered, and their excitation and propagation are discussed from various view points. First, the formalism based on the complex integral theory is presented, where the surface is assumed to be covered with an infinitesimally thin metallic film, and it is shown how the excitation and propagation of SH-type waves are affected by the surface perturbation. Then, the analysis is extended to a periodic grating structure, and the behavior of SH-type SAWs under the grating structure is discussed. Finally, the origin of the leaky nature is explained.

  12. Monitoring of Surface Grinding process using Acoustic Emission (AE) with emphasis on Cutting Fluid selection

    NASA Astrophysics Data System (ADS)

    Nisal, Tejas V.

    Correct selection of cutting fluid is an important step in all machining operations. In this study, experiments were designed and conducted on AISI 52100 steel to determine the effects of using different cutting fluids in Surface Grinding. The grinding parameters varied were wheel speed, feed, depth of cut and type of cutting fluid. The grinding responses studied here were Acoustic Emission (AE) Signals, Normal and Tangential Forces on the workpiece surface, Grinding Temperature and Surface Roughness. Potential of Acoustic Emission technique as a tool to provide efficient real-time knowledge and monitoring of the grinding process, is tested in this research. AERMS values were used to analyses the process characteristics. This paper proposes four different statistical models for predicting Grinding Temperature, Force, Acoustic Emission (AERMS) and Roughness, based on grinding parameters. This research concludes that the selection of Cutting Fluids influence the Surface finish, AE signals, Temperature and grinding Forces measured. Further, prediction of surface roughness during the grinding process using AE signal monitoring is demonstrated in this work.

  13. Surface acoustical intensity measurements on a diesel engine

    NASA Technical Reports Server (NTRS)

    Mcgary, M. C.; Crocker, M. J.

    1980-01-01

    The use of surface intensity measurements as an alternative to the conventional selective wrapping technique of noise source identification and ranking on diesel engines was investigated. A six cylinder, in line turbocharged, 350 horsepower diesel engine was used. Sound power was measured under anechoic conditions for eight separate parts of the engine at steady state operating conditions using the conventional technique. Sound power measurements were repeated on five separate parts of the engine using the surface intensity at the same steady state operating conditions. The results were compared by plotting sound power level against frequency and noise source rankings for the two methods.

  14. The Effects of Surfaces on the Aerodynamics and Acoustics of Jet Flows

    NASA Technical Reports Server (NTRS)

    Smith, Matthew J.; Miller, Steven A. E.

    2013-01-01

    Aircraft noise mitigation is an ongoing challenge for the aeronautics research community. In response to this challenge, low-noise aircraft concepts have been developed that exhibit situations where the jet exhaust interacts with an airframe surface. Jet flows interacting with nearby surfaces manifest a complex behavior in which acoustic and aerodynamic characteristics are altered. In this paper, the variation of the aerodynamics, acoustic source, and far-field acoustic intensity are examined as a large at plate is positioned relative to the nozzle exit. Steady Reynolds-Averaged Navier-Stokes solutions are examined to study the aerodynamic changes in the field-variables and turbulence statistics. The mixing noise model of Tam and Auriault is used to predict the noise produced by the jet. To validate both the aerodynamic and the noise prediction models, results are compared with Particle Image Velocimetry (PIV) and free-field acoustic data respectively. The variation of the aerodynamic quantities and noise source are examined by comparing predictions from various jet and at plate configurations with an isolated jet. To quantify the propulsion airframe aeroacoustic installation effects on the aerodynamic noise source, a non-dimensional number is formed that contains the flow-conditions and airframe installation parameters.

  15. Separation of Escherichia coli bacteria from peripheral blood mononuclear cells using standing surface acoustic waves.

    PubMed

    Ai, Ye; Sanders, Claire K; Marrone, Babetta L

    2013-10-01

    A microfluidic device was developed to separate heterogeneous particle or cell mixtures in a continuous flow using acoustophoresis. In this device, two identical surface acoustic waves (SAWs) generated by interdigital transducers (IDTs) propagated toward a microchannel, which accordingly built up a standing surface acoustic wave (SSAW) field across the channel. A numerical model, coupling a piezoelectric effect in the solid substrate and acoustic pressure in the fluid, was developed to provide a better understanding of SSAW-based particle manipulation. It was found that the pressure nodes across the channel were individual planes perpendicular to the solid substrate. In the separation experiments, two side sheath flows hydrodynamically focused the injected particle or cell mixtures into a very narrow stream along the centerline. Particles flowing through the SSAW field experienced an acoustic radiation force that highly depends on the particle properties. As a result, dissimilar particles or cells were laterally attracted toward the pressure nodes at different magnitudes, and were eventually switched to different outlets. Two types of fluorescent microspheres with different sizes were successfully separated using the developed device. In addition, Escherichia coli bacteria premixed in peripheral blood mononuclear cells (PBMCs) were also efficiently isolated using the SSAW-base separation technique. Flow cytometric analysis on the collected samples found that the purity of separated E. coli bacteria was 95.65%.

  16. Combining Electrochemical Impedance Spectroscopy and Surface Plasmon Resonance into one Simultaneous Read-Out System for the Detection of Surface Interactions

    PubMed Central

    Vandenryt, Thijs; Pohl, Andrea; van Grinsven, Bart; Thoelen, Ronald; De Ceuninck, Ward; Wagner, Patrick; Opitz, Jörg

    2013-01-01

    In this article we describe the integration of impedance spectroscopy (EIS) and surface plasmon resonance (SPR) into one surface analytic device. A polydimethylsiloxane (PDMS) flow cell is created, matching the dimensions of a commercially available sensor chip used for SPR measurements. This flow cell allowed simultaneous measurements between an EIS and a SPR setup. After a successful integration, a proof of principle study was conducted to investigate any signs of interference between the two systems during a measurement. The flow cell was rinsed with 10 mM Tris-HCl and 1× PBS buffer in an alternating manner, while impedance and shifts of the resonance angle were monitored. After achieving a successful proof of principle, a usability test was conducted. It was assessed whether simultaneous detection occurred when: (i) Protein A is adsorbed to the gold surface of the chip; (ii) The non-occupied zone is blocked with BSA molecules and (iii) IgG1 is bound to the Protein A. The results indicate a successful merge between SPR and EIS. PMID:24172282

  17. RF Surface Impedance Measurement of Polycrystalline and Large Grain Nb Disk Sample at 7.5 GHz

    SciTech Connect

    Xiao, Binping; Geng, Rongli; Kelley, Michael J.; Marhauser, Frank; Phillips, H. Larry; Reece, Charles E.; Wang, Haipeng

    2009-11-01

    A Surface Impedance Characterization (SIC) system has been proposed at the 2005 SRF workshop and recently updated as detailed at the 2009 PAC conference. Currently the SIC system can measure samples in a temperature range from 2K to 20K exposed to an RF magnetic flux density of less than 3mT. We report on new results of a BCP etched large grain Nb sample measured with this system as compared with previous results of a BCP etched polycrystalline Nb sample. The design of an upgraded SIC system for use at higher magnetic flux densities is on the way to more efficiently investigate correlations between local material characteristics and associated SRF properties, both for preparation studies of bulk niobium and also new thin film SRF developments.

  18. Electrochemical impedance spectroscopy and surface plasmon resonance studies of DNA hybridization on gold/SiOx interfaces.

    PubMed

    Manesse, Maël; Stambouli, Valerie; Boukherroub, Rabah; Szunerits, Sabine

    2008-08-01

    The use of Au/SiO(x) interfaces for the investigation of DNA hybridization using electrochemical impedance spectroscopy (EIS) and surface plasmon resonance (SPR) simultaneously is demonstrated. Standard glass chemistry was used to link single-stranded DNA (ss-DNA) on aldehyde-terminated Au/SiO(x) interfaces. The layer thickness and amount of grafted oligonucleotides (ODNs) were calculated from SPR on the basis of a multilayer system of glass/Ti/Au/SiO(x)/grafted molecule. Capacitance and resistance values of the modified interface before and after hybridization were calculated from EIS data using an equivalent circuit and allowed the affinity rate constant, K(A) = 4.07 x 10(5) M(-1), to be determined. The EIS results were comparable to those obtained by SPR hybridization kinetics recorded in parallel.

  19. On the formation of nanostructures on a CdTe surface, stimulated by surface acoustic waves under nanosecond laser irradiation

    SciTech Connect

    Vlasenko, A. I.; Baidullaeva, A.; Veleschuk, V. P. Mozol, P. E.; Boiko, N. I.; Litvin, O. S.

    2015-02-15

    The formation of nanoscale structures in the unirradiated part of a p-CdTe crystal surface irradiated by a nanosecond ruby laser is revealed and investigated. It is shown that their formation is caused by the effect of the long-range action of a laser pulse with an intensity of I = 20 MW/cm{sup 2}. Nanoscale-structure formation is explained by the influence of the pressure gradient of the surface acoustic wave, in particular, within the “vacancy-pump” mechanism on the surface.

  20. Evaluation of peak-free electromechanical piezo-impedance and electromagnetic contact sensing using metamaterial surface plasmons for load monitoring

    NASA Astrophysics Data System (ADS)

    Gopal Madhav Annamdas, Venu; Kiong Soh, Chee

    2017-01-01

    Continuous structural health monitoring (SHM) and delayed SHM techniques can be contact/ contactless, surface bonded/embedded, wired/wireless and active/passive actuator-sensor systems which transfer the recorded condition of the structure to the base station almost instantaneously or with time delay respectively. The time between fatal crack initiation and its propagation leading to the collapse of key infrastructures such as aerospace, nuclear facilities, oil and gas is mostly short. Timely discovery of structural problem depends heavily on the scanning period in well-established techniques like piezoelectric (PZT) based electromechanical impedance (EMI) technique. This often takes much scanning time due to the acquisition of resonant structural peaks at all frequencies in the considered bandwidth; thus poses a challenge for its implementation in practice. On the other hand, recently developed strain sensors based on metamaterials and their breeds such as nested split-ring resonators, localized surface plasmons (LSP), etc, employ measurement of reflected or transmitted signal, with super-fast scanning in the order of at most 1/100th of the time taken by the EMI technique. This paper articulates faster measurements by reducing unnecessary resonant structural peaks and focusing on rapid monitoring using PZT and metamaterial plasmons. Our research adopted wired PZT and wireless LSP communications with impedance analyser and vector network analyser respectively. We present integrated and complementary nature of these techniques, which can be processed rapidly for key infrastructures with great effectiveness. This integration can result in both continuous and delayed SHM techniques based on time or frequency or both domains.

  1. Valveless impedance micropump with integrated magnetic diaphragm.

    PubMed

    Lee, Chia-Yen; Chen, Zgen-Hui

    2010-04-01

    This study presents a planar valveless impedance-based micropump for biomedical applications comprising a lower glass substrate patterned with a copper micro-coil, a microchannel, an upper glass cover plate, and a PDMS diaphragm with an electroplated magnet on its upper surface. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnet. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which in turn produces a net flow. The performance of the micropump is characterized experimentally. The experimental results show that a maximum diaphragm deflection of 30 microm is obtained when the micro-coil is supplied with an input current of 0.5 A. The corresponding flow rate is found to be 1.5 microl/sec when the PDMS membrane is driven by an actuating frequency of 240 Hz.

  2. Monolithic Thin Film SAW (Surface Acoustic Wave) Structures.

    DTIC Science & Technology

    1984-09-01

    storage " regions. The device is simple to fabricate, requiring neither pn or Schottky diode * arrays for -ignal storage. The memory function is...and is close to the value for LiNbOj Several convolvers and diode storage correlators which exploit the banidwidth advantage of the Sezawa mode have...fLUILcti of the properties~ of the interface. Surface state storage was subscquenitly replaced by more easily controlled and repeatable diode storage

  3. Vapor sensing by means of a ZnO-on-Si surface acoustic wave resonator

    NASA Astrophysics Data System (ADS)

    Martin, S. J.; Schweizer, K. S.; Schwartz, S. S.; Gunshor, R. L.

    Surface Acoustic Wave (SAW) devices can function as sensitive detectors of vapors. The high surface acoustic energy density of the device makes it extremely sensitive to the presence of molecules adsorbed from the gas phase. Mass loading by the adsorbate is the primary mechanism for the surface wave velocity perturbation. If the device is used as the frequency control element of an oscillator, perturbations in wave velocity on the order of 10 parts per billion may be resolved by means of a frequency counter. Zno-on-Si SAW resonators have been examined as vapor sensors. The piezoelectric ZnO layer permits transduction between electrical and acoustic energies, as well as endowing the surface with particular adsorptive properties. These devices exhibit C-values up to 12,000 at a resonant frequency of 109 MHZ. The resonant frequency of the device shifts upon exposure to a vapor-air mixture, with a transient response which is distinct for each of the organic vapors tested. Due to the permeability of the polycrystalline ZnO layer, the instantaneous reversibility of the resonant frequency shift is found to depend on the type of adsorbed molecule.

  4. Tunable far-field acoustic imaging by two-dimensional sonic crystal with concave incident surface

    NASA Astrophysics Data System (ADS)

    Shen, Feng-Fu; Lu, Dan-Feng; Zhu, Hong-Wei; Ji, Chang-Ying; Shi, Qing-Fan

    2017-01-01

    An additional concave incident surface comprised of two-dimensional (2D) sonic crystals (SCs) is employed to tune the acoustic image in the far-field region. The tunability is realized through changing the curvature of the concave surface. To explain the tuning mechanism, a simple ray-trace analysis is demonstrated based on the wave-beam negative refractive law. Then, a numerical confirmation is carried out. Results show that both the position and the intensity of the image can be tuned by the introduced concave surface.

  5. Enhanced sensitive love wave surface acoustic wave sensor designed for immunoassay formats.

    PubMed

    Puiu, Mihaela; Gurban, Ana-Maria; Rotariu, Lucian; Brajnicov, Simona; Viespe, Cristian; Bala, Camelia

    2015-05-05

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT) applications.

  6. An airborne acoustic method to reconstruct a dynamically rough flow surface.

    PubMed

    Krynkin, Anton; Horoshenkov, Kirill V; Van Renterghem, Timothy

    2016-09-01

    Currently, there is no airborne in situ method to reconstruct with high fidelity the instantaneous elevation of a dynamically rough surface of a turbulent flow. This work proposes a holographic method that reconstructs the elevation of a one-dimensional rough water surface from airborne acoustic pressure data. This method can be implemented practically using an array of microphones deployed over a dynamically rough surface or using a single microphone which is traversed above the surface at a speed that is much higher than the phase velocity of the roughness pattern. In this work, the theory is validated using synthetic data calculated with the Kirchhoff approximation and a finite difference time domain method over a number of measured surface roughness patterns. The proposed method is able to reconstruct the surface elevation with a sub-millimeter accuracy and over a representatively large area of the surface. Since it has been previously shown that the surface roughness pattern reflects accurately the underlying hydraulic processes in open channel flow [e.g., Horoshenkov, Nichols, Tait, and Maximov, J. Geophys. Res. 118(3), 1864-1876 (2013)], the proposed method paves the way for the development of non-invasive instrumentation for flow mapping and characterization that are based on the acoustic holography principle.

  7. Surface Acoustic Wave Devices as Chemical Vapor Sensors

    DTIC Science & Technology

    2009-03-26

    Plasma-Enhanced Chemical Vapor Deposited Surfaces,” Advanced Materials, 2006. 45. S . C. Huang, K. D. Caldwell , J. N. Lin, H . K. Wang, and J. N. Herron...exposure, 45 s develop, titanium. 59 Figure 4.4: SEM image of one of the devices from Series 3. 4.2 Testing AFRL- Designed SAW Devices Through...Approach for the Detection of Explosives,” Jour- nal of Hazardous Materials,, vol. 144, pp. 15–28, June 2007. 4. M. H . Ervin, S . J. Kilpatrick, C

  8. Broadband cylindrical acoustic cloak for linear surface waves in a fluid.

    PubMed

    Farhat, M; Enoch, S; Guenneau, S; Movchan, A B

    2008-09-26

    We describe the first practical realization of a cylindrical cloak for linear surface liquid waves. This structured metamaterial bends surface waves radiated by a closely located acoustic source over a finite interval of Hertz frequencies. We demonstrate theoretically its unique mechanism using homogenization theory: the cloak behaves as an effective anisotropic fluid characterized by a diagonal stress tensor in a cylindrical basis. A low azimuthal viscosity is achieved, where the fluid flows most rapidly. Numerical simulations demonstrate that the homogenized cloak behaves like the actual structured cloak. We experimentally analyze the decreased backscattering of a fluid with low viscosity and finite density (methoxynonafluorobutane) from a cylindrical rigid obstacle surrounded by the cloak when it is located a couple of wavelengths away from the acoustic source.

  9. Low-loss unidirectional transducer for high frequency surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Biryukov, S. V.; Martin, G.; Schmidt, H.; Wall, B.

    2011-10-01

    A multi-track unidirectional transducer for surface acoustic wave devices is presented. This transducer consists of periodic cells containing in each of the multiple tracks, only two electrodes and two gaps with quarter period width. So the structure has maximal possible dimensions of its elements for a cell period equal to one wavelength. In spite of current technological limitations this permits to implement unidirectional transducers in GHz range. In contrast to known structures with active tracks only, the structure contains alternating both active transducer tracks and passive reflector tracks with different apertures comparable to surface acoustic wave (SAW) wavelength. The tracks strongly interact due to diffraction of waves excited by such electrode structure on a piezoelectric substrate. A structure analysis by means of finite element method shows that complete unidirectionality can be reached. First experimental results are given.

  10. Solitary surface acoustic waves and bulk solitons in nanosecond and picosecond laser ultrasonics.

    PubMed

    Hess, Peter; Lomonosov, Alexey M

    2010-02-01

    Recent achievements of nonlinear acoustics concerning the realization of solitons and solitary waves in crystals and their surfaces attained by nanosecond and picosecond laser ultrasonics are discussed and compared. The corresponding pump-probe setups are described, which allow an all-optical contact-free excitation and detection of short strain pulses in the broad frequency range between 10 MHz and about 300 GHz. The formation of solitons in the propagating longitudinal strain pulses is investigated for nonlinear media with intrinsic lattice-based dispersion. The excitation of solitary surface acoustic waves is realized by a geometric film-based dispersion effect. Future developments and potential applications of nonlinear nanosecond and picosecond ultrasonics are discussed.

  11. Electron Impedances

    SciTech Connect

    P Cameron

    2011-12-31

    It is only recently, and particularly with the quantum Hall effect and the development of nanoelectronics, that impedances on the scale of molecules, atoms and single electrons have gained attention. In what follows the possibility that characteristic impedances might be defined for the photon and the single free electron is explored is some detail, the premise being that the concepts of electrical and mechanical impedances are relevant to the elementary particle. The scale invariant quantum Hall impedance is pivotal in this exploration, as is the two body problem and Mach's principle.

  12. Development of a GaAs Monolithic Surface Acoustic Wave Integrated Circuit

    SciTech Connect

    Baca, A.G.; Casalnuovo, S.C.; Drummond, T.J.; Frye, G.C.; Heller, E.J.; Hietala, V.M.; Klem, J.F.

    1999-03-08

    An oscillator technology using surface acoustic wave delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. The oscillator consists of a two-port SAW delay line in a feedback loop with a four-stage GaAs MESFET amplifier. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. These oscillators are also promising for other RF applications.

  13. The Impact of Very High Frequency Surface Reverberation on Coherent Acoustic Propagation and Modeling

    DTIC Science & Technology

    2014-09-30

    months into this 36 month project, and work in this initial phase has focused on laboratory measurements of high frequency surface scattering and...continuously measured with a wire wave gauge placed slightly downstream of the acoustic transducers. The transducers themselves were placed in the...16 bit data acquisition system sampling at 4 MHz. Figure 1. Geometry for the high frequency scattering experiment in the wind-wave simulator

  14. Surface Acoustic-Wave-Induced Magnetoresistance Oscillations in a Two-Dimensional Electron Gas

    NASA Astrophysics Data System (ADS)

    Robinson, John P.; Kennett, Malcolm P.; Cooper, Nigel R.; Fal'Ko, Vladimir I.

    2004-07-01

    We study the geometrical commensurability oscillations imposed on the resistivity of 2D electrons in a perpendicular magnetic field by a propagating surface acoustic wave (SAW). We show that, for ω<ωc, this effect contains an anisotropic dynamical classical contribution increasing the resistivity and a nonequilibrium quantum contribution isotropically decreasing the resistivity, and we predict zero-resistance states associated with geometrical commensurability at large SAW amplitude.

  15. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    NASA Astrophysics Data System (ADS)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1-x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (<0.5%). The performance of the two types of devices was also investigated and compared, using acoustofluidics as an example. The AlScN/Si SAW devices achieved much lower threshold powers for the acoustic streaming and pumping of liquid droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  16. Imaging textural variation in the acoustoelastic coefficient of aluminum using surface acoustic waves.

    PubMed

    Ellwood, R; Stratoudaki, T; Sharples, S D; Clark, M; Somekh, M G

    2015-11-01

    Much interest has arisen in nonlinear acoustic techniques because of their reported sensitivity to variations in residual stress, fatigue life, and creep damage when compared to traditional linear ultrasonic techniques. However, there is also evidence that the nonlinear acoustic properties are also sensitive to material microstructure. As many industrially relevant materials have a polycrystalline structure, this could potentially complicate the monitoring of material processes when using nonlinear acoustics. Variations in the nonlinear acoustoelastic coefficient on the same length scale as the microstructure of a polycrystalline sample of aluminum are investigated in this paper. This is achieved by the development of a measurement protocol that allows imaging of the acoustoelastic response of a material across a samples surface at the same time as imaging the microstructure. The development, validation, and limitations of this technique are discussed. The nonlinear acoustic response is found to vary spatially by a large factor (>20) between different grains. A relationship is observed when the spatial variation of the acoustoelastic coefficient is compared to the variation in material microstructure.

  17. Detection of Volatile Organics Using a Surface Acoustic Wave Array System

    SciTech Connect

    ANDERSON, LAWRENCE F.; BARTHOLOMEW, JOHN W.; CERNOSEK, RICHARD W.; COLBURN, CHRISTOPHER W.; CROOKS, R.M.; MARTINEZ, R.F.; OSBOURN, GORDON C.; RICCO, A.J.; STATON, ALAN W.; YELTON, WILLIAM G.

    1999-10-14

    A chemical sensing system based on arrays of surface acoustic wave (SAW) delay lines has been developed for identification and quantification of volatile organic compounds (VOCs). The individual SAW chemical sensors consist of interdigital transducers patterned on the surface of an ST-cut quartz substrate to launch and detect the acoustic waves and a thin film coating in the SAW propagation path to perturb the acoustic wave velocity and attenuation during analyte sorption. A diverse set of material coatings gives the sensor arrays a degree of chemical sensitivity and selectivity. Materials examined for sensor application include the alkanethiol-based self-assembled monolayer, plasma-processed films, custom-synthesized conventional polymers, dendrimeric polymers, molecular recognition materials, electroplated metal thin films, and porous metal oxides. All of these materials target a specific chemical fi.mctionality and the enhancement of accessible film surface area. Since no one coating provides absolute analyte specificity, the array responses are further analyzed using a visual-empirical region-of-influence (VERI) pattern recognition algorithm. The chemical sensing system consists of a seven-element SAW array with accompanying drive and control electronics, sensor signal acquisition electronics, environmental vapor sampling hardware, and a notebook computer. Based on data gathered for individual sensor responses, greater than 93%-accurate identification can be achieved for any single analyte from a group of 17 VOCs and water.

  18. Materials analyses and electrochemical impedance of implantable metal electrodes.

    PubMed

    Howlader, Matiar M R; Ul Alam, Arif; Sharma, Rahul P; Deen, M Jamal

    2015-04-21

    Implantable electrodes with high flexibility, high mechanical fixation and low electrochemical impedance are desirable for neuromuscular activation because they provide safe, effective and stable stimulation. In this paper, we report on detailed materials and electrical analyses of three metal implantable electrodes - gold (Au), platinum (Pt) and titanium (Ti) - using X-ray photoelectron spectroscopy (XPS), scanning acoustic microscopy, drop shape analysis and electrochemical impedance spectroscopy. We investigated the cause of changes in electrochemical impedance of long-term immersed Au, Pt and Ti electrodes on liquid crystal polymers (LCPs) in phosphate buffered saline (PBS). We analyzed the surface wettability, surface and interface defects and the elemental depth profile of the electrode-adhesion layers on the LCP. The impedance of the electrodes decreased at lower frequencies, but increased at higher frequencies compared with that of the short-term immersion. The increase of impedances was influenced by the oxidation of the electrode/adhesion-layers that affected the double layer capacitance behavior of the electrode/PBS. The oxidation of the adhesion layer for all the electrodes was confirmed by XPS. Alkali ions (sodium) were adsorbed on the Au and Pt surfaces, but diffused into the Ti electrode and LCPs. The Pt electrode showed a higher sensitivity to surface and interface defects than that of Ti and Au electrodes. These findings may be useful when designing electrodes for long-term implantable devices.

  19. Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves

    SciTech Connect

    Martin, R. W.; Sathish, S.; Blodgett, M. P.

    2013-01-25

    The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

  20. Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors

    DOEpatents

    Hietala, Susan Leslie; Hietala, Vincent Mark; Tigges, Chris Phillip

    2001-01-01

    A method and apparatus for measuring surface changes, such as mass uptake at various pressures, in a thin-film material, in particular porous membranes, using multiple differently-configured acoustic sensors.

  1. Rayleigh surface acoustic wave as an efficient heating system for biological reactions: investigation of microdroplet temperature uniformity.

    PubMed

    Roux-Marchand, Thibaut; Beyssen, Denis; Sarry, Frederic; Elmazria, Omar

    2015-04-01

    When a microdroplet is put on the Rayleigh surface acoustic wave path, longitudinal waves are radiated into the liquid and induce several phenomena such as the wellknown surface acoustic wave streaming. At the same time, the temperature of the microdroplet increases as it has been shown. In this paper, we study the temperature uniformity of a microdroplet heated by Rayleigh surface acoustic wave for discrete microfluidic applications such as biological reactions. To precisely ascertain the temperature uniformity and not interfere with the biological reaction, we used an infrared camera. We then tested the temperature uniformity as a function of three parameters: the microdroplet volume, the Rayleigh surface acoustic wave frequency, and the continuous applied radio frequency power. Based on these results, we propose a new device structure to develop a future lab on a chip based on reaction temperatures.

  2. Single-component single-partial acoustic surface waves in cubic crystals with surface distortion taken into account

    NASA Astrophysics Data System (ADS)

    Klochko, M. S.

    2014-06-01

    The surface waves and bulk acoustic bands were studied taking into account the interaction between the nearest and next-nearest neighbors in a cubic crystal. Expressions for the dispersion relations, the frequencies at which the surface waves split off the bulk spectrum, and the parameters of the amplitude attenuation have been obtained for the crystalline systems in which the surface waves are single-component and single-partial. The calculations were conducted taking into account the discrete nature of crystal lattice for arbitrary values of the two-dimensional wave vector. The analysis has demonstrated that the results obtained in the long-wavelength limit are in full agreement with those calculated in the framework of linear nonlocal elasticity theory. The influence of an adsorbed surface monolayer on the characteristics of the surface waves was studied.

  3. Mathematical simulation of sound propagation in a flow channel with impedance walls

    NASA Astrophysics Data System (ADS)

    Osipov, A. A.; Reent, K. S.

    2012-07-01

    The paper considers the specifics of calculating tonal sound propagating in a flow channel with an installed sound-absorbing device. The calculation is performed on the basis of numerical integrating on linearized nonstationary Euler equations using a code developed by the authors based on the so-called discontinuous Galerkin method. Using the linear theory of small perturbations, the effect of the sound-absorbing lining of the channel walls is described with the modified value of acoustic impedance proposed by the authors, for which, under flow channel conditions, the traditional classification of the active and reactive types of lining in terms of the real and imaginary impedance values, respectively, remains valid. To stabilize the computation process, a generalized impedance boundary condition is proposed in which, in addition to the impedance value itself, some additional parameters are introduced characterizing certain fictitious properties of inertia and elasticity of the impedance surface.

  4. Superlensing effect for surface acoustic waves in a pillar-based phononic crystal with negative refractive index

    SciTech Connect

    Addouche, Mahmoud Al-Lethawe, Mohammed A. Choujaa, Abdelkrim Khelif, Abdelkrim

    2014-07-14

    We demonstrate super resolution imaging for surface acoustic waves using a phononic structure displaying negative refractive index. This phononic structure is made of a monolithic square lattice of cylindrical pillars standing on a semi-infinite medium. The pillars act as acoustic resonator and induce a surface propagating wave with unusual dispersion. We found, under specific geometrical parameters, one propagating mode that exhibits negative refraction effect with negative effective index close to −1. Furthermore, a flat lens with finite number of pillars is designed to allow the focusing of an acoustic point source into an image with a resolution of (λ)/3 , overcoming the Rayleigh diffraction limit.

  5. Surface acoustic waves induced micropatterning of cells in gelatin methacryloyl (GelMA) hydrogels.

    PubMed

    Naseer, Shahid M; Manbachi, Amir; Samandari, Mohamadmahdi; Walch, Philipp; Gao, Yuan; Zhang, Yu Shrike; Davoudi, Farideh; Wang, Wesley; Abrinia, Karen; Cooper, Jonathan M; Khademhosseini, Ali; Shin, Su Ryon

    2017-02-14

    Acoustic force patterning is an emerging technology that provides a platform to control the spatial location of cells in a rapid, accurate, yet contactless manner. However, very few studies have been reported on the usage of acoustic force patterning for the rapid arrangement of biological objects, such as cells, in a three-dimensional (3D) environment. In this study, we report on a bio-acoustic force patterning technique, which uses surface acoustic waves (SAWs) for the rapid arrangement of cells within an extracellular matrix-based hydrogel such as gelatin methacryloyl (GelMA). A proof-of-principle was achieved through both simulations and experiments based on the in-house fabricated piezoelectric SAW transducers, which enabled us to explore the effects of various parameters on the performance of the built construct. The SAWs were applied in a fashion that generated standing SAWs (SSAWs) on the substrate, the energy of which subsequently was transferred into the gel, creating a rapid, and contactless alignment of the cells (<10 s, based on the experimental conditions). Following ultraviolet radiation induced photo-crosslinking of the cell encapsulated GelMA pre-polymer solution, the patterned cardiac cells readily spread after alignment in the GelMA hydrogel and demonstrated beating activity in 5-7 days. The described acoustic force assembly method can be utilized not only to control the spatial distribution of the cells inside a 3D construct, but can also preserve the viability and functionality of the patterned cells (e.g. beating rates of cardiac cells). This platform can be potentially employed in a diverse range of applications, whether it is for tissue engineering, in vitro cell studies, or creating 3D biomimetic tissue structures.

  6. Efficient Solution of Three-Dimensional Problems of Acoustic and Electromagnetic Scattering by Open Surfaces

    NASA Technical Reports Server (NTRS)

    Turc, Catalin; Anand, Akash; Bruno, Oscar; Chaubell, Julian

    2011-01-01

    We present a computational methodology (a novel Nystrom approach based on use of a non-overlapping patch technique and Chebyshev discretizations) for efficient solution of problems of acoustic and electromagnetic scattering by open surfaces. Our integral equation formulations (1) Incorporate, as ansatz, the singular nature of open-surface integral-equation solutions, and (2) For the Electric Field Integral Equation (EFIE), use analytical regularizes that effectively reduce the number of iterations required by iterative linear-algebra solution based on Krylov-subspace iterative solvers.

  7. Surface acoustic wave response to optical absorption by graphene composite film.

    PubMed

    Chivukula, Venkata S; Ciplys, Daumantas; Kim, Jin Ho; Rimeika, Romualdas; Xu, Jimmy M; Shur, Michael S

    2012-02-01

    Propagation of surface acoustic waves in YZ LiNbO3 overlaid with graphene flakes has been investigated and its optical response to illumination by 633-nm light from a He-Ne laser was studied. The heating of the sample surface caused by optical absorption by the graphene led to a downshift in the transmitted SAW phase caused by the wave velocity's dependence on temperature. The proposed simple model based on optothermal SAW phase modulation was found to be in good agreement with the experimental results.

  8. The role of a coarse surface layer in impeding evaporation from gravel bars

    NASA Astrophysics Data System (ADS)

    Edmaier, Katharina; Peter, Molnar; Clémentine, Cyprien; Paolo, Burlando

    2010-05-01

    The presence of a coarse surface layer (CSL) on bars in gravel bed rivers is expected to have an influence on evaporation rates from these surfaces and thereby on the water content in the underlying gravel-sand matrix. A statistically significant increase in soil water content in the presence of a CSL has recently been demonstrated in outdoor experiments by Meier and Hauer (2010). The authors argued that the CSL leads to a reduction in available energy for evaporation, decreases the advection of water vapour from the evaporating surface and reduces the supply of water from the underlying matrix to the evaporating surface. These findings are important because the germination of seeds and vegetative reproduction of riparian species on gravel bars are presumed to be driven by local soil moisture availability. Therefore local conditions of erosion-deposition which lead to the presence or absence of a CSL could be a crucial parameter for successful vegetation establishment on gravel bars. We conducted a simple laboratory experiment to verify the findings of Meier and Hauer (2010) under more controlled conditions. In the experiment 6 cylindrical buckets with a surface area of 720 cm2 and total volume of 19500 cm3 were filled with a sand-gravel mixture to replicate the sediment composition in the Thur River, Switzerland (d50 = 8 mm). This site is part of the research project RECORD (www.record.ethz.ch), which focuses on river restoration issues. Three treatments were investigated, each with a CSL of different thickness (H = 0, 40 and 80 mm) with one replicate each, roughly corresponding to 2 and 4 layers of typical CSL gravel diameters in the Thur River. We also measured the temperature in the sediment matrix underneath the CSL. The samples were saturated over several days and subsequently gravitationally drained in order to retain water held only by capillary forces as the initial condition. The samples were then weighed daily for 47 days and the evaporation rates and

  9. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    SciTech Connect

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-07

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11–54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  10. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    NASA Astrophysics Data System (ADS)

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-01

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11-54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  11. Generalized Discrete Model of Systems with Distributed Feedback Based on Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Sveshnikov, B. V.; Bagdasaryan, A. S.

    2016-11-01

    We have developed a self-consistent physical model that improves the accuracy of calculating the characteristics of the devices based on both surface and pseudosurface acoustic waves. The model is free from restrictions inherent in the well-known method of coupled modes and other phenomenological methods for studying distributed systems. The compact relationships describing all the characteristics of the acoustoelectric transducers of all types with allowance for the possible directionality of their radiation and its propagation loss are obtained using analytical solution of the difference equations. The method for determining the spatial orientation of the elastic-polarization ellipse in an anisotropic crystal, which allows one to unambiguously calculate the phase shift between the oscillations of two coupled dynamical subsystems, i.e., elastic displacements and the corresponding electric field, is proposed. The obtained results, which considerably facilitate the task of fast and accurate design of various devices on the basis of surface and pseudosurface acoustic waves, are valid in the general case for any frequency, including the harmonics of the frequency of the fundamental acoustic synchronism.

  12. Particle Separation inside a Sessile Droplet with Variable Contact Angle Using Surface Acoustic Waves.

    PubMed

    Destgeer, Ghulam; Jung, Jin Ho; Park, Jinsoo; Ahmed, Husnain; Sung, Hyung Jin

    2017-01-03

    A sessile droplet of water carrying polystyrene microparticles of different diameters was uniformly exposed to high frequency surface acoustic waves (SAWs) produced by an interdigitated transducer (IDT). We investigated the concentration behavior of the microparticles as the SAWs generated a strong acoustic streaming flow (ASF) inside the water droplet and exerted a direct acoustic radiation force (ARF) on the suspended particles, the magnitude of which depended upon the particle diameter. As a result of the ARF, the microparticles were concentrated according to their diameters at different positions inside the sessile droplet placed in the path of the SAW, right in front of the IDT. The microparticle concentration behavior changed as the sessile droplet contact angle with the substrate was varied by adding surfactant to the water or by gradually evaporating the water. The positions at which the smaller and larger microparticles were concentrated remained distinguishable, even at very different experimental conditions. The long-term exposure of the droplets to the SAWs was accompanied by the gradual evaporation of the carrier fluid, which dynamically changed the droplet contact angle as well as the concentration of particles. Complete evaporation of the fluid left behind several concentrated yet separated clusters of particles on the substrate surface. The effect of the droplet contact angle on particles' concentration behavior and consequent separation of particles has been uniquely studied in this SAW-based report.

  13. Radiation by Sources on Perfectly Conducting Convex Cylinders with an Impedance Surface Patch.

    DTIC Science & Technology

    1980-01-01

    far zone) by~a unit strenth magiletic line source at Q’ on the surface s* W (Q’ or &| P1 and T’ (Q’ or Or) are the magnetic fields indu2ed at Q’ r on th...U -- = - (a to0 . 0 0 m 4- 0 4- 04 0-0 1 - .0 4’ U-- ~4- 4 0 n4- -- C_ to S~0- 4J C >1 cu S)-0’ (0 C 0)~ 00 =3 .r aCCA 50 It is observed from these...follows: Gh - - . d_ jF4I 1 2 2 P1 -~ _~_~E (k 2 _ 2 ) 2 ah (k 2 _ 2 ) 1 lahd) 1- ] (B-20) The first two terms in (B-20) can be evaluated using

  14. Surface Impedance Measurements of Single Crystal MgB2 Films for Radiofrequency Superconductivity Applications

    SciTech Connect

    Binping Xiao, Xin Zhao, Joshua Spradlin, Charles Reece, Michael Kelley, Teng Tan, Xi Xiaoxing

    2012-07-01

    We report microstructure analyses and superconducting radiofrequency (SRF) measurements of large scale epitaxial MgB{sub 2} films. MgB{sub 2} films on 5 cm dia. sapphire disks were fabricated by a Hybrid Physical Chemical Vapor Deposition (HPCVD) technique. The electron-beam backscattering diffraction (EBSD) results suggest that the film is a single crystal complying with a MgB{sub 2}(0001) {parallel} Al{sub 2}O{sub 3}(0001) epitaxial relationship. The SRF properties of different film thicknesses (200 nm and 350 nm) were evaluated under different temperatures and applied fields at 7.4 GHz. A surface resistance of 9 {+-} 2 {mu}{Omega} has been observed at 2.2 K.

  15. Investigation of 3D surface acoustic waves in granular media with 3-color digital holography

    NASA Astrophysics Data System (ADS)

    Leclercq, Mathieu; Picart, Pascal; Penelet, Guillaume; Tournat, Vincent

    2017-01-01

    This paper reports the implementation of digital color holography to investigate elastic waves propagating along a layer of a granular medium. The holographic set-up provides simultaneous recording and measurement of the 3D dynamic displacement at the surface. Full-field measurements of the acoustic amplitude and phase at different excitation frequencies are obtained. It is shown that the experimental data can be used to obtain the dispersion curve of the modes propagating in this granular medium layer. The experimental dispersion curve and that obtained from a finite element modeling of the problem are found to be in good agreement. In addition, full-field images of the interaction of an acoustic wave guided in the granular layer with a buried object are also shown.

  16. Estimating sub-surface dispersed oil concentration using acoustic backscatter response.

    PubMed

    Fuller, Christopher B; Bonner, James S; Islam, Mohammad S; Page, Cheryl; Ojo, Temitope; Kirkey, William

    2013-05-15

    The recent Deepwater Horizon disaster resulted in a dispersed oil plume at an approximate depth of 1000 m. Several methods were used to characterize this plume with respect to concentration and spatial extent including surface supported sampling and autonomous underwater vehicles with in situ instrument payloads. Additionally, echo sounders were used to track the plume location, demonstrating the potential for remote detection using acoustic backscatter (ABS). This study evaluated use of an Acoustic Doppler Current Profiler (ADCP) to quantitatively detect oil-droplet suspensions from the ABS response in a controlled laboratory setting. Results from this study showed log-linear ABS responses to oil-droplet volume concentration. However, the inability to reproduce ABS response factors suggests the difficultly in developing meaningful calibration factors for quantitative field analysis. Evaluation of theoretical ABS intensity derived from the particle size distribution provided insight regarding method sensitivity in the presence of interfering ambient particles.

  17. Single-drop liquid phase microextraction accelerated by surface acoustic wave.

    PubMed

    Zhang, Anliang; Zha, Yan

    2013-03-01

    A single-drop liquid phase microextraction method is presented, in which surface acoustic wave (SAW) is used for accelerating extraction speed. A pair of interdigital transducers with 27.5 MHz center frequency is fabricated on a 128° yx-LiNbO3 substrate. A radio frequency signal is applied to one of interdigital transducers to excite SAW. Plastic straw is filled with PDMS, leaving 1 mL for holding sample solution. Plastic straw with sample solution droplet is then dipping into extractant, into which SAW is radiated. Mass transportation from sample solution to extractant drop is accelerated due to acoustic streaming, and extraction time is decreased. An ionic liquid and an acid green-25 solution are used for extraction experiments. Results show that the extraction process is almost finished within 2 min, and extraction speed is increased with radio frequency signal power.

  18. Effects of dissipation on propagation of surface electromagnetic and acoustic waves

    NASA Astrophysics Data System (ADS)

    Nagaraj, Nagaraj

    With the recent emergence of the field of metamaterials, the study of subwavelength propagation of plane waves and the dissipation of their energy either in the form of Joule losses in the case of electomagnetic waves or in the form of viscous dissipation in the case of acoustic waves in different interfaced media assumes great importance. With this motivation, I have worked on problems in two different areas, viz., plasmonics and surface acoustics. The first part (chapters 2 & 3) of the dissertation deals with the emerging field of plasmonics. Researchers have come up with various designs in an effort to fabricate efficient plasmonic waveguides capable of guiding plasmonic signals. However, the inherent dissipation in the form of Joule losses limits efficient usage of surface plasmon signal. A dielectric-metal-dielectric planar structure is one of the most practical plasmonic structures that can serve as an efficient waveguide to guide electromagnetic waves along the metal-dielectric boundary. I present here a theoretical study of propagation of surface plasmons along a symmetric dielectric-metal-dielectric structure and show how proper orientation of the optical axis of the anisotropic substrate enhances the propagation length. An equation for propagation length is derived in a wide range of frequencies. I also show how the frequency of coupled surface plasmons can be modulated by changing the thickness of the metal film. I propose a Kronig-Penny model for the plasmonic crystal, which in the long wavelength limit, may serve as a homogeneous dielectric substrate with high anisotropy which do not exist for natural optical crystals. In the second part (chapters 4 & 5) of the dissertation, I discuss an interesting effect of extraordinary absorption of acoustic energy due to resonant excitation of Rayleigh waves in a narrow water channel clad between two metal plates. Starting from the elastic properties of the metal plates, I derive a dispersion equation that gives

  19. Investigation of phononic crystals for dispersive surface acoustic wave ozone sensors

    NASA Astrophysics Data System (ADS)

    Westafer, Ryan S.

    The object of this research was to investigate dispersion in surface phononic crystals (PnCs) for application to a newly developed passive surface acoustic wave (SAW) ozone sensor. Frequency band gaps and slow sound already have been reported for PnC lattice structures. Such engineered structures are often advertised to reduce loss, increase sensitivity, and reduce device size. However, these advances have not yet been realized in the context of surface acoustic wave sensors. In early work, we computed SAW dispersion in patterned surface structures and we confirmed that our finite element computations of SAW dispersion in thin films and in one dimensional surface PnC structures agree with experimental results obtained by laser probe techniques. We analyzed the computations to guide device design in terms of sensitivity and joint spectral operating point. Next we conducted simulations and experiments to determine sensitivity and limit of detection for more conventional dispersive SAW devices and PnC sensors. Finally, we conducted extensive ozone detection trials on passive reflection mode SAW devices, using distinct components of the time dispersed response to compensate for the effect of temperature. The experimental work revealed that the devices may be used for dosimetry applications over periods of several days.

  20. Microwave Surface Impedance Investigation of the Superconducting Proximity Effect in Superconductor/normal - Bilayer Structures

    NASA Astrophysics Data System (ADS)

    Pambianchi, Michael Scott

    1995-01-01

    This thesis seeks to develop a clearer understanding of the microwave-frequency electrodynamics of thin normal metal films which are superconducting by virtue of intimate contact with a superconducting film. It is found in superconductar/normal -metal (S/N) bilayer thin films of Nb/Cu and Nb/Al that the effective penetration depth and the surface resistance decrease precipitously as the temperature is lowered toward zero, unlike the exponentially slow variation of these quantities with temperature in a bare superconducting film. This behavior is associated with the temperature dependence of the characteristic penetration length scale of the superconducting order parameter in the normal metal film, which diverges as T to 0. However, theory predicts that the normal metal films under study in this thesis, having thicknesses in the range 100-800A, are much thinner than this decay length and hence should not show strong temperature dependence as this length scale diverges. We conclude that this theory is not adequate for describing the spatial dependence of the induced order parameter very near the S/N interface, and develop an improved model of the electrodynamics of proximity-coupled systems with very thin normal metal layers which reproduces the observed data. We demonstrate that a much shorter effective decay length for the order parameter in the normal layer can correctly describe the extent of proximity coupling in these structures. The advantages of the parallel-plate resonator technique in exploring these effects are presented. The distinctive ability of the technique to simultaneously gather data on the properties of the induced superconducting condensate (penetration depth data) and the properties of the spectrum of excitations above it (surface resistance data) in the proximity-coupled normal metal set the technique apart from previous methods, and allow it to study the very thin normal metal layers on which data are presented here. In addition to the much

  1. Surface acoustic wave induced particle manipulation in a PDMS channel--principle concepts for continuous flow applications.

    PubMed

    Johansson, Linda; Enlund, Johannes; Johansson, Stefan; Katardjiev, Ilia; Yantchev, Ventsislav

    2012-04-01

    A device for acoustic particle manipulation in the 40 MHz range for continuous-flow operation in a 50 μm wide PDMS channel has been evaluated. Unidirectional interdigital transducers on a Y-cut Z-propagation lithium nixobate wafer were used to excite a surface acoustic wave that generated an acoustic standing wave inside the microfluidic channel. It was shown that particle alignment nodes with different inter-node spacing could be obtained, depending on device design and driving frequency. The observed inter-node spacing differed from the standard half-wavelength inter-node spacing generally employed in bulk acoustic transducer excited resonant systems. This effect and the related issue of acoustic node positions relative the channel walls, which is fundamental for most continuous flow particle manipulation operations in channels, was evaluated in measurements and simulations. Specific applications of particle separation and alignment where these systems can offer benefits relative state-of the art designs were identified.

  2. Modulated exponential films generated by surface acoustic waves and their role in liquid wicking and aerosolization at a pinned drop

    NASA Astrophysics Data System (ADS)

    Taller, Daniel; Go, David B.; Chang, Hsueh-Chia

    2013-05-01

    The exponentially decaying acoustic pressure of scattered surface acoustic waves (SAWs) at the contact line of a liquid film pinned to filter paper is shown to sustain a high curvature conic tip with micron-sized modulations whose dimension grows exponentially from the tip. The large negative capillary pressure in the film, necessary for offsetting the large positive acoustic pressure at the contact line, also creates significant negative hydrodynamic pressure and robust wicking action through the paper. An asymptotic analysis of this intricate pressure matching between the quasistatic conic film and bulk drop shows that the necessary SAW power to pump liquid from the filter paper and aerosolize, expressed in terms of the acoustic pressure scaled by the drop capillary pressure, grows exponentially with respect to twice the acoustic decay constant multiplied by the drop length, with a universal preexponential coefficient. Global rapid aerosolization occurs at a SAW power twice as high, beyond which the wicking rate saturates.

  3. Modulated exponential films generated by surface acoustic waves and their role in liquid wicking and aerosolization at a pinned drop.

    PubMed

    Taller, Daniel; Go, David B; Chang, Hsueh-Chia

    2013-05-01

    The exponentially decaying acoustic pressure of scattered surface acoustic waves (SAWs) at the contact line of a liquid film pinned to filter paper is shown to sustain a high curvature conic tip with micron-sized modulations whose dimension grows exponentially from the tip. The large negative capillary pressure in the film, necessary for offsetting the large positive acoustic pressure at the contact line, also creates significant negative hydrodynamic pressure and robust wicking action through the paper. An asymptotic analysis of this intricate pressure matching between the quasistatic conic film and bulk drop shows that the necessary SAW power to pump liquid from the filter paper and aerosolize, expressed in terms of the acoustic pressure scaled by the drop capillary pressure, grows exponentially with respect to twice the acoustic decay constant multiplied by the drop length, with a universal preexponential coefficient. Global rapid aerosolization occurs at a SAW power twice as high, beyond which the wicking rate saturates.

  4. Cross-calibrating interferon-γ detection by using eletrochemical impedance spectroscopy and paraboloidal mirror enabled surface plasmon resonance interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Meng-Wei; Chang, Hao-Jung; Lee, Shu-sheng; Lee, Chih-Kung

    2016-03-01

    Tuberculosis is a highly contagious disease such that global latent patient can be as high as one third of the world population. Currently, latent tuberculosis was diagnosed by stimulating the T cells to produce the biomarker of tuberculosis, i.e., interferon-γ. In this paper, we developed a paraboloidal mirror enabled surface plasmon resonance (SPR) interferometer that has the potential to also integrate ellipsometry to analyze the antibody and antigen reactions. To examine the feasibility of developing a platform for cross calibrating the performance and detection limit of various bio-detection techniques, electrochemical impedance spectroscopy (EIS) method was also implemented onto a biochip that can be incorporated into this newly developed platform. The microfluidic channel of the biochip was functionalized by coating the interferon-γ antibody so as to enhance the detection specificity. To facilitate the processing steps needed for using the biochip to detect various antigen of vastly different concentrations, a kinetic mount was also developed to guarantee the biochip re-positioning accuracy whenever the biochip was removed and placed back for another round of detection. With EIS being utilized, SPR was also adopted to observe the real-time signals on the computer in order to analyze the success of each biochip processing steps such as functionalization, wash, etc. Finally, the EIS results and the optical signals obtained from the newly developed optical detection platform was cross-calibrated. Preliminary experimental results demonstrate the accuracy and performance of SPR and EIS measurement done at the newly integrated platform.

  5. Cell-surface galectin-3 confers resistance to TRAIL by impeding trafficking of death receptors in metastatic colon adenocarcinoma cells.

    PubMed

    Mazurek, N; Byrd, J C; Sun, Y; Hafley, M; Ramirez, K; Burks, J; Bresalier, R S

    2012-03-01

    Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis and preferentially kills tumor cells by engaging specific glycosylated death receptors, resulting in the internalization of ligand/receptor complexes and recruitment of the initiator caspase-8 to an activation platform known as the death-inducing signaling complex (DISC). However, emergence of TRAIL-resistant sub-populations may contribute to therapeutic failure. To investigate resistance mechanisms, we isolated a stable TRAIL-resistant sub-population of the metastatic colon cancer cell line LS-LIM6, designated LIM6-TR. LIM6-TR cells are impaired in endocytosis of TRAIL/death receptors complexes and failed to recruit/activate caspase-8 to the DISC upon TRAIL stimulation. Differential activation of Wnt and JNK pathways is not responsible for acquisition of TRAIL resistance. LIM6-TR cells display a marked increase in cell-surface expression of galectin-3, an endogenous lectin, which co-localizes with and binds death receptors. Silencing of galectin-3 restores TRAIL sensitivity and promotes TRAIL-mediated endocytosis of TRAIL/death receptors complexes. Inhibitors of galectin-3 and glycosylation also re-sensitize LIM6-TR to TRAIL and restore internalization of ligand/receptors complexes. These studies identify a novel TRAIL-resistance mechanism in which galectin-3 impedes trafficking of death receptor by anchoring them in glycan nano-clusters, blocking the execution of the apoptosis signal.

  6. Kinetics of electrochemically controlled surface reactions on bulk and thin film metals studied with Fourier transform impedance spectroscopy and surface plasmon resonance techniques

    NASA Astrophysics Data System (ADS)

    Assiongbon, Kankoe A.

    2005-07-01

    In the work presented in this thesis, the surface sensitive electrochemical techniques of cyclic voltametry (CV), potential step (PS) and Fourier transform impedance spectroscopy (FT-EIS), as well as the optical technique of surface plasmon resonance (SPR), were used to probe a wide variety of surface processes at various metal/liquid interface. Three polycrystalline metals (Au, Ta and Cu) and a Cr-coated gold film were used for these studies in different aqueous environments. A combination of CV with FT-EIS and PS was used to investigate electronic and structural proprieties of a modified bulk electrode of Au. This experimental system involved under potential deposition (UPD) of Bi3+ on Au in a supporting aqueous electrolyte containing ClO-4 . UPD range of Bi3+ was determined, and adsorption kinetics of Bi3+ in the presence of coadsorbing anion, ClO-4 were quantified. Potentiodynamic growth of oxide films of Ta in the following electrolytes NaNO3, NaNO3 + 5wt% H2O2, NaOH and NaOH + 5wt% H2O2 had been investigated. The oxide films were grown in the range -0.1 → +0.4V (high electric field) at a scan rate of 10 mV/s. Time resolved A.C. impedance spectroscopy measurements in the frequency range (0.1--20 KHz) were performed to characterize the surface reactions of oxide formation. The results are interpreted in terms of charge conductivity O2- through the oxide film, and disintegration of H2O2 into OH-. In a high pH medium (pH 12), dissociation of H2O2 was catalytically enhanced. This led to destabilization of the electrogenerated tantalum oxide surface film in the form of a soluble hexatantalate species. In contrast with the electrolytes, NaNO3, NaNO3 + 5wt% H2O2, NaOH, where only the oxide growth was observed, the A.C. impedance spectroscopy measurements in NaOH + 5wt% H 2O2 showed competition between oxide formation and its removal. These results are relevant for chemical slurry design in chemical mechanical polishing (CMP) of Ta. Further investigations were

  7. Wave guide impedance matching method and apparatus

    DOEpatents

    Kronberg, James W.

    1990-01-01

    A technique for modifying the end portion of a wave guide, whether hollow or solid, carrying electromagnetic, acoustic or optical energy, to produce a gradual impedance change over the length of the end portion, comprising the cutting of longitudinal, V-shaped grooves that increase in width and depth from beginning of the end portion of the wave guide to the end of the guide so that, at the end of the guide, no guide material remains and no surfaces of the guide as modified are perpendicular to the direction of energy flow. For hollow guides, the grooves are cut beginning on the interior surface; for solid guides, the grooves are cut beginning on the exterior surface. One or more resistive, partially conductive or nonconductive sleeves can be placed over the exterior of the guide and through which the grooves are cut to smooth the transition to free space.

  8. Polydimethylsiloxane-LiNbO3 surface acoustic wave micropump devices for fluid control into microchannels.

    PubMed

    Girardo, Salvatore; Cecchini, Marco; Beltram, Fabio; Cingolani, Roberto; Pisignano, Dario

    2008-09-01

    This paper presents prototypical microfluidic devices made by hybrid microchannels based on piezoelectric LiNbO(3) and polydimethylsiloxane. This system enables withdrawing micropumping by acoustic radiation in microchannels. The withdrawing configuration, integrated on chip, is here quantitatively investigated for the first time, and found to be related to the formation and coalescence dynamics of droplets within the microchannel, primed by surface acoustic waves. The growth dynamics of droplets is governed by the water diffusion on LiNbO(3), determining the advancement of the fluid front. Observed velocities are up to 2.6 mm s(-1) for 30 dBm signals applied to the interdigital transducer, corresponding to tens of nl s(-1), and the micropumping dynamics is described by a model taking into account an acoustic power exponentially decaying upon travelling along the microchannel. This straighforward and flexible micropumping approach is particularly promising for the withdrawing of liquids in lab-on-chip devices performing cycling transport of fluids and biochemical reactions.

  9. Manipulating particle trajectories with phase-control in surface acoustic wave microfluidics.

    PubMed

    Orloff, Nathan D; Dennis, Jaclyn R; Cecchini, Marco; Schonbrun, Ethan; Rocas, Eduard; Wang, Yu; Novotny, David; Simmonds, Raymond W; Moreland, John; Takeuchi, Ichiro; Booth, James C

    2011-12-01

    We present a 91 MHz surface acoustic wave resonator with integrated microfluidics that includes a flow focus, an expansion region, and a binning region in order to manipulate particle trajectories. We demonstrate the ability to change the position of the acoustic nodes by varying the electronic phase of one of the transducers relative to the other in a pseudo-static manner. The measurements were performed at room temperature with 3 μm diameter latex beads dispersed in a water-based solution. We demonstrate the dependence of nodal position on pseudo-static phase and show simultaneous control of 9 bead streams with spatial control of -0.058 μm/deg ± 0.001 μm/deg. As a consequence of changing the position of bead streams perpendicular to their flow direction, we also show that the integrated acoustic-microfluidic device can be used to change the trajectory of a bead stream towards a selected bin with an angular control of 0.008 deg/deg ± 0.000(2) deg/deg.

  10. Microfluidic pumping through miniaturized channels driven by ultra-high frequency surface acoustic waves

    SciTech Connect

    Shilton, Richie J.; Travagliati, Marco; Beltram, Fabio; Cecchini, Marco

    2014-08-18

    Surface acoustic waves (SAWs) are an effective means to pump fluids through microchannel arrays within fully portable systems. The SAW-driven acoustic counterflow pumping process relies on a cascade phenomenon consisting of SAW transmission through the microchannel, SAW-driven fluid atomization, and subsequent coalescence. Here, we investigate miniaturization of device design, and study both SAW transmission through microchannels and the onset of SAW-driven atomization up to the ultra-high-frequency regime. Within the frequency range from 47.8 MHz to 754 MHz, we show that the acoustic power required to initiate SAW atomization remains constant, while transmission through microchannels is most effective when the channel widths w ≳ 10 λ, where λ is the SAW wavelength. By exploiting the enhanced SAW transmission through narrower channels at ultra-high frequencies, we discuss the relevant frequency-dependent length scales and demonstrate the scaling down of internal flow patterns and discuss their impact on device miniaturization strategies.

  11. Particle Accumulation in a Microchannel and Its Reduction by a Standing Surface Acoustic Wave (SSAW).

    PubMed

    Sriphutkiat, Yannapol; Zhou, Yufeng

    2017-01-07

    Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 μm microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO₃ wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging.

  12. Quantitative determination of size and shape of surface-bound DNA using an acoustic wave sensor.

    PubMed

    Tsortos, Achilleas; Papadakis, George; Mitsakakis, Konstantinos; Melzak, Kathryn A; Gizeli, Electra

    2008-04-01

    DNA bending plays a significant role in many biological processes, such as gene regulation, DNA replication, and chromosomal packing. Understanding how such processes take place and how they can, in turn, be regulated by artificial agents for individual oriented therapies is of importance to both biology and medicine. In this work, we describe the application of an acoustic wave device for characterizing the conformation of DNA molecules tethered to the device surface via a biotin-neutravidin interaction. The acoustic energy dissipation per unit mass observed upon DNA binding is directly related to DNA intrinsic viscosity, providing quantitative information on the size and shape of the tethered molecules. The validity of the above approach was verified by showing that the predesigned geometries of model double-stranded and triple-helix DNA molecules could be quantitatively distinguished: the resolution of the acoustic measurements is sufficient to allow discrimination between same size DNA carrying a bent at different positions along the chain. Furthermore, the significance of this analysis to the study of biologically relevant systems is shown during the evaluation of DNA conformational change upon protein (histone) binding.

  13. Recent advances in microfluidic actuation and micro-object manipulation via surface acoustic waves.

    PubMed

    Destgeer, Ghulam; Sung, Hyung Jin

    2015-07-07

    The realization of microscale total analysis systems and lab-on-a-chip technologies requires efficient actuation (mixing, pumping, atomizing, nebulizing, driving, etc.) of fluids on the microscopic scale and dexterous manipulation (separation, sorting, trapping, concentration, merging, patterning, aligning, focusing, etc.) of micro-objects (cells, droplets, particles, nanotubes, etc.) in open (sessile droplets) as well as confined spaces (microchannels/chambers). These capabilities have been recently achieved using powerful acoustofluidic techniques based on high-frequency (10-1000 MHz) surface acoustic waves (SAWs). SAW-based miniaturized microfluidic devices are best known for their non-invasive properties, low costs, and ability to manipulate micro-objects in a label-free manner. The energy-efficient SAWs are also compatible with conventional microfabrication technologies. The present work critically analyses recent reports describing the use of SAWs in microfluidic actuation and micro-object manipulation. Acoustofluidic techniques may be categorized according to the use of travelling SAWs (TSAWs) or standing SAWs (SSAWs). TSAWs are used to actuate fluids and manipulate micro-objects via acoustic streaming flow (ASF) as well as acoustic radiation force (ARF). SSAWs are mainly used for micro-object manipulation and are rarely employed for microfluidic actuation. We have reviewed reports of new technological developments that have not been covered in other recent reviews. In the end, we describe the future prospects of SAW-based acoustofluidic technologies.

  14. Particle Accumulation in a Microchannel and Its Reduction by a Standing Surface Acoustic Wave (SSAW)

    PubMed Central

    Sriphutkiat, Yannapol; Zhou, Yufeng

    2017-01-01

    Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 μm microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO3 wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging. PMID:28067852

  15. Modeling of the acoustic field of thermally induced ultrasonic emission from a spherical cavity surface.

    PubMed

    Wang, Dongdong; Hu, Hanping; Wang, Zedong

    2015-02-01

    Thermo-acoustic (TA) ultrasound has attracted considerable interest during the last decade for its many advantages over the conventional electro-acoustic ultrasound. In this paper, a general expression of the acoustic pressure field of thermally induced ultrasonic emission from a spherical cavity surface is derived by using a fully thermally-mechanically coupled TA model. The characteristics and regularities of ultrasound from spherical focusing TA emitter can therefore be studied in detail. It is found that, for the TA emission in sphere shell, wideband flat amplitude-frequency response pattern, the most important feature of TA ultrasound in an open space from a technical standpoint, is seriously disrupted by wave interference occurring in spherical cavity. The dependences of sound pressure of TA ultrasound in spherical cavity on the heating frequency, the inner radius of spherical cavity, the location in spherical cavity, and the thickness of TA sample layer, as well as the type and filling pressure of gas in cavity are given and discussed. The currently used planar TA solution is only the special case for spherical cavity with infinite radius of the analytical solution developed in this work, which would be of significance for more comprehensive guide to understanding and using TA ultrasound.

  16. Quantitative measurements of acoustic emissions from cavitation at the surface of a stone in response to a lithotripter shock wave.

    PubMed

    Chitnis, Parag V; Cleveland, Robin O

    2006-04-01

    Measurements are presented of acoustic emissions from cavitation collapses on the surface of a synthetic kidney stone in response to shock waves (SWs) from an electrohydraulic lithotripter. A fiber optic probe hydrophone was used for pressure measurements, and passive cavitation detection was used to identify acoustic emissions from bubble collapse. At a lithotripter charging voltage of 20 kV, the focused SW incident on the stone surface resulted in a peak pressure of 43 +/- 6 MPa compared to 23 +/- 4 MPa in the free field. The focused SW incident upon the stone appeared to be enhanced due to the acoustic emissions from the forced cavitation collapse of the preexisting bubbles. The peak pressure of the acoustic emission from a bubble collapse was 34 +/- 15 MPa, that is, the same magnitude as the SWs incident on the stone. These data indicate that stresses induced by focused SWs and cavitation collapses are similar in magnitude thus likely play a similar role in stone fragmentation.

  17. Guided shear horizontal surface acoustic wave sensors for chemical and biochemical detection in liquids.

    PubMed

    Josse, F; Bender, F; Cernose, R W

    2001-12-15

    The design and performance of guided shear horizontal surface acoustic wave (guided SH-SAW) devices on LiTaO3 substrates are investigated for high-sensitivity chemical and biochemical sensors in liquids. Despite their structural similarity to Rayleigh SAW, SH-SAWs often propagate slightly deeper within the substrate, hence preventing the implementation of high-sensitivity detectors. The device sensitivity to mass and viscoelastic loading is increased using a thin guiding layer on the device surface. Because of their relatively low shear wave velocity, various polymers including poly(methyl methacrylate) (PMMA) and cyanoethyl cellulose (cured or cross-linked) are investigated as the guiding layers to trap the acoustic energy near the sensing surface. The devices have been tested in biosensing and chemical sensing experiments. Suitable design principles for these applications are discussed with regard to wave guidance, electrical passivation of the interdigital transducers from the liquid environments, acoustic loss, and sensor signal distortion. In biosensing experiments, using near-optimal PMMA thickness of approximately 2 microm, mass sensitivity greater than 1500 Hz/(ng/mm2) is demonstrated, resulting in a minimum detection limit less than 20 pg/mm2. For chemical sensor experiments, it is found that optimal waveguide thickness must be modified to account for the chemically sensitive layer which also acts to guide the SH-SAW. A detection limit of 780 (3 x peak-to-peak noise) or 180 ppb (3 x rms noise) is estimated from the present measurements for some organic compounds in water.

  18. Development of a surface acoustic wave sensor for in-situ monitoring of volatile organic compounds.

    SciTech Connect

    McGrath, Lucas K.; Wright, Jerome L.; Ho, Clifford Kuofei; Rawlinson, Kim Scott; Lindgren, Eric Richard

    2003-08-01

    This paper describes the development of a surface-acoustic-wave (SAW) sensor that is designed to be operated continuously and in situ to detect volatile organic compounds. A ruggedized stainless-steel package that encases the SAW device and integrated circuit board allows the sensor to be deployed in a variety of media including air, soil, and even water. Polymers were optimized and chosen based on their response to chlorinated aliphatic hydrocarbons (e.g., trichloroethylene), which are common groundwater contaminants. Initial testing indicates that a running-average data-logging algorithm can reduce the noise and increase the sensitivity of the in-situ sensor.

  19. Surface acoustic admittance of highly porous open-cell, elastic foams

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1983-01-01

    This work presents a comprehensive study of the surface acoustic admittance properties of graded sizes of open-cell foams that are highly porous and elastic. The intrinsic admittance as well as properties of samples of finite depth were predicted and then measured for sound at normal incidence over a frequency range extending from about 35-3500 Hz. The agreement between theory and experiment for a range of mean pore size and volume porosity is excellent. The implications of fibrous structure on the admittance of open-cell foams is quite evident from the results.

  20. Amplification and directional emission of surface acoustic waves by a two-dimensional electron gas

    SciTech Connect

    Shao, Lei; Pipe, Kevin P.

    2015-01-12

    Amplification of surface acoustic waves (SAWs) by electron drift in a two-dimensional electron gas (2DEG) is analyzed analytically and confirmed experimentally. Calculations suggest that peak power gain per SAW radian occurs at a more practical carrier density for a 2DEG than for a bulk material. It is also shown that SAW emission with tunable directionality can be achieved by modulating a 2DEG's carrier density (to effect SAW generation) in the presence of an applied DC field that amplifies SAWs propagating in a particular direction while attenuating those propagating in the opposite direction.