Effects of Acoustic Waves on Buried Tunnel Structures Under an Impact Load

In this paper, the transmission and reflection of acoustic waves into and from an underground tunnel are investigated by producing an impact load on the ground and measuring the acoustic pressure levels at different time intervals. For this purpose, a sound detector is placed on the ground and then from an arbitrary location on the surface, acoustic waves are transmitted into the ground from an acoustic source. The pressure levels of acoustic waves transmitted into the tunnel space and reflected back to the ground surface are measured, and the effects of several parameters on the attenuation of acoustic pressure levels of transmitted and reflected sound waves are evaluated. Moreover, the effects of parameters such as soil type, concrete type and thickness, buried depth of the underground structure and also the effect of acoustic absorbers on the transmission, propagation and reflection of acoustic waves into and from the tunnel are investigated. The results obtained indicate that the two parameters of soil type and buried depth have the greatest effect on the transmission of acoustic waves, whereas all the parameters considered are important with regard to the reflection of acoustic waves. In addition, it was observed that the use of acoustic absorbers in tunnel structures has a significant effect on the attenuation of transmitted and reflected acoustic waves.

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Acoustophoretic Control of Microparticle Transport Using Dual-Wavelength Surface Acoustic Wave Devices

Micromachines ◽

10.3390/mi10010052 ◽

2019 ◽

Vol 10 (1) ◽

pp. 52 ◽

Cited By ~ 4

Author(s):

Jin-Chen Hsu ◽

Chih-Hsun Hsu ◽

Yeo-Wei Huang

Keyword(s):

Particle Motion ◽

Acoustic Waves ◽

Acoustic Pressure ◽

Acoustic Radiation ◽

Surface Acoustic Waves ◽

Microfluidic Channel ◽

Radiation Force ◽

Dual Wavelength ◽

Single Frequency ◽

Motion Trajectories

We present a numerical and experimental study of acoustophoretic manipulation in a microfluidic channel using dual-wavelength standing surface acoustic waves (SSAWs) to transport microparticles into different outlets. The SSAW fields were excited by interdigital transducers (IDTs) composed of two different pitches connected in parallel and series on a lithium niobate substrate such that it yielded spatially superimposed and separated dual-wavelength SSAWs, respectively. SSAWs of a singltablee target wavelength can be efficiently excited by giving an RF voltage of frequency determined by the ratio of the velocity of the SAW to the target IDT pitch (i.e., f = cSAW/p). However, the two-pitch IDTs with similar pitches excite, less efficiently, non-target SSAWs with the wavelength associated with the non-target pitch in addition to target SSAWs by giving the target single-frequency RF voltage. As a result, dual-wavelength SSAWs can be formed. Simulated results revealed variations of acoustic pressure fields induced by the dual-wavelength SSAWs and corresponding influences on the particle motion. The acoustic radiation force in the acoustic pressure field was calculated to pinpoint zero-force positions and simulate particle motion trajectories. Then, dual-wavelength SSAW acoustofluidic devices were fabricated in accordance with the simulation results to experimentally demonstrate switching of SSAW fields as a means of transporting particles. The effects of non-target SSAWs on pre-actuating particles were predicted and observed. The study provides the design considerations needed for the fabrication of acoustofluidic devices with IDT-excited multi-wavelength SSAWs for acoustophoresis of microparticles.

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Ultra-High Frequency Sound Waves for Microparticle Separation

Volume 2A: Fora, Part 2 ◽

10.1115/ajkfluids2015-18682 ◽

2015 ◽

Author(s):

Ghulam Destgeer ◽

Anas Alazzam ◽

Hyung Jin Sung

Keyword(s):

Acoustic Waves ◽

High Frequency ◽

Surface Acoustic Waves ◽

Microfluidic Channel ◽

Sound Waves ◽

Ultra High Frequency ◽

High Frequency Sound ◽

Frequency Sound ◽

Sheath Fluid ◽

Order Of Magnitude

In this study, we have demonstrated a particle separation device taking advantage of the ultra-high frequency sound waves. The sound waves, in the form of surface acoustic waves, are produced by an acoustofluidic platform build on top of a piezoelectric substrate bonded to a microfluidic channel. The particles’ mixture, pumped through the microchannel, is focused using a sheath fluid. A travelling surface acoustic wave (TSAW), propagating normal to the flow, interacts with the particles and deflect them from their original path to induce size-based separation in a continuous flow. We initially started the experiment with 40 MHz TSAWs for deflecting 10 μm diameter polystyrene particles but failed. However, larger diameter particles (∼ 30 μm) were successfully deflected from their streamlines and separated from the smaller particles (∼ 10 μm) using TSAWs with 40 MHz frequency. The separation of smaller diameter particles (3, 5 and 7 μm) was also achieved using an order of magnitude higher-frequency (∼ 133 MHz) TSAWs.

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Sculpting and Aerosolizing Pinned Liquid Films With Localized Acoustic Pressures of Surface Acoustic Waves

Volume 9: Micro- and Nano-Systems Engineering and Packaging, Parts A and B ◽

10.1115/imece2012-87249 ◽

2012 ◽

Author(s):

Daniel Taller ◽

Hsueh-Chia Chang ◽

David B. Go

Keyword(s):

Contact Angle ◽

Numerical Modeling ◽

Contact Line ◽

Acoustic Waves ◽

Acoustic Pressure ◽

Surface Acoustic Waves ◽

Liquid Films ◽

Solid Substrate ◽

Planar Surface ◽

Bulk Film

Due to viscous decay, a planar surface acoustic wave (SAW) diffracting from a solid substrate into a liquid film produces a time-averaged, exponentially decaying acoustic pressure in the film. We show that if the film is pinned against a bounding wall, the localized acoustic pressure generates a sequence of surface drops at the contact line, whose dimensions decay in the same exponential manner as the localized acoustic pressure. The undulating interfacial profile near the contact line also inherits this exponential decay, such that the averaged contact angle is exponentially small. The bulk film topology and the aerosolization mechanism are hence insensitive to the wettability of the surface but are controlled only by the localized acoustic pressure and the decaying undulations it produces at the contact line. The size distribution of surface drops is collapsed under the exponential scaling that depends only on the SAW decay rate and amplitude. Numerical modeling based on the Young-Laplace equation is used to model the liquid profile and to predict two aerosolization regimes.

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Quantitative assessment of acoustic pressure in one-dimensional acoustofluidic devices driven by standing surface acoustic waves

Applied Physics Letters ◽

10.1063/1.4996543 ◽

2017 ◽

Vol 111 (4) ◽

pp. 043508 ◽

Cited By ~ 3

Author(s):

Shilei Liu ◽

Guangyao Xu ◽

Zhengyang Ni ◽

Xiasheng Guo ◽

Linjiao Luo ◽

...

Keyword(s):

Acoustic Waves ◽

Quantitative Assessment ◽

Acoustic Pressure ◽

Surface Acoustic Waves ◽

One Dimensional

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Non-contact three-dimensional cell cluster formation on demand in open dishware using focused surface acoustic waves through a couplant layer

10.22541/au.163822587.77984326/v1 ◽

2021 ◽

Author(s):

Jiyang Mei ◽

Aditya Vasan ◽

Uri Magaram ◽

Kenjiro Takemura ◽

Sreekanth Chalasani ◽

...

Keyword(s):

Acoustic Waves ◽

Drug Testing ◽

Cluster Formation ◽

Surface Acoustic Waves ◽

Three Dimensional ◽

Petri Dish ◽

Hek293 Cells ◽

Sound Waves ◽

The Media ◽

Dimensional Cell

Three-dimensional cell agglomerates are broadly useful in tissue engineering and drug testing. We report a well-free method to form large (1-mm) multicellular clusters using 100-MHz surface acoustic waves (SAW) without direct contact with the media or cells. A fluid couplant is used to transformthe SAW into acoustic streaming in the cell-laden media held in a petri dish. The couplant transmits longitudinal sound waves, forming a Lamb wave in the petri dish that, in turn, produces longitudinal sound in the media. Due to recirculation, human embryonic kidney (HEK293) cells in the dish are carried to the center of the coupling location, forming a cluster in less than 10 min. A few minutes later, these clusters may then be translated and merged to form large agglomerations, and even repeatedly folded to produce a roughly spherical shape of over 1 mm in diameter for incubation—without damaging the existing intercellular bonds. Calcium ion signaling through these clusters and confocal images of multiprotein junctional complexes suggest a continuous tissue construct: intercellular communication. They may be formed at will, and the method is feasibly useful for formation of numerous agglomerates in a single petri dish.

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Towards a Multi-Interdigital Transducer Configuration to Combine Focusing and Trapping of Microparticles within a Microfluidic Platform: A 3D Numerical Analysis

Engineering Proceedings ◽

10.3390/ecsa-8-11256 ◽

2021 ◽

Vol 10 (1) ◽

pp. 31

Author(s):

Gianluca Mezzanzanica ◽

Olivier Français

Keyword(s):

Numerical Analysis ◽

Acoustic Waves ◽

Wave Amplitude ◽

Acoustic Pressure ◽

Surface Acoustic Waves ◽

Microfluidic Channels ◽

Pressure Pattern ◽

Focusing Effect ◽

Particle Focusing ◽

Micro Particles

In Lab-On-a-chip devices, the separation and manipulation of micro-particles within microfluidic channels are important operations in the process of biological analyses. In this study, the microfluidic flow is coupled with acoustic waves through a 3D multi-physics numerical solution in order to generate optimized acoustic pressure pattern. Exploiting interdigital transducers (IDTs), surface acoustic waves (SAWs) are generated on the surface of a piezoelectric substrate (lithium niobate). These waves interfere constructively to generate a standing pressure field within a fluid contained in a microchannel placed between them. Several studies and applications have been reported exploiting two facing IDTs, effective in particle focusing due to the acoustic radiation force developed by the acoustic pressure. In this work, a configuration made by four IDTs is investigated to enhance the focusing effect and provide trapping capabilities. A complex matrix of pressure wave nodes (zero wave amplitude) and antinodes (maximum wave amplitude) is generated and optimized to acquire the right acoustic pressure pattern. Results obtained show particle focusing effects but also trapping on specific sites depending on the distribution of waves. These innovative results, based on multiphysics 3D numerical analysis, highlight the versatility and the efficiency of this configuration depending on the design of the microfluidic structure implemented in the SAW-based platform. Applications towards biological cell sorting and assembling can be considered based on this principle.

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Characterization of RF Sputtered ZnO Piezoelectric Films Using Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114050 ◽

1975 ◽

Vol 33 ◽

pp. 86-87

Author(s):

Kemining W. Yeh ◽

Richard S. Muller ◽

Wei-Kuo Wu ◽

Jack Washburn

Keyword(s):

Integrated Circuit ◽

Acoustic Waves ◽

New Technology ◽

Surface Acoustic Waves ◽

Electromechanical Properties ◽

Leading Role ◽

Saw Devices ◽

Transmission Electron ◽

High Degree

Considerable and continuing interest has been shown in the thin film transducer fabrication for surface acoustic waves (SAW) in the past few years. Due to the high degree of miniaturization, compatibility with silicon integrated circuit technology, simplicity and ease of design, this new technology has played an important role in the design of new devices for communications and signal processing. Among the commonly used piezoelectric thin films, ZnO generally yields superior electromechanical properties and is expected to play a leading role in the development of SAW devices.

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