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

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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Enhanced particle focusing in microfluidic channels with standing surface acoustic waves

Microelectronic Engineering ◽

10.1016/j.mee.2009.12.010 ◽

2010 ◽

Vol 87 (5-8) ◽

pp. 1204-1206 ◽

Cited By ~ 13

Author(s):

Q. Zeng ◽

H.W.L. Chan ◽

X.Z. Zhao ◽

Y. Chen

Keyword(s):

Acoustic Waves ◽

Surface Acoustic Waves ◽

Microfluidic Channels ◽

Particle Focusing

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Visualization of Surface Acoustic Waves in Thin Liquid Films

Scientific Reports ◽

10.1038/srep21980 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 20

Author(s):

R. W. Rambach ◽

J. Taiber ◽

C. M. L. Scheck ◽

C. Meyer ◽

J. Reboud ◽

...

Keyword(s):

Liquid Film ◽

Acoustic Waves ◽

Low Cost ◽

Thin Liquid Film ◽

Surface Acoustic Waves ◽

Liquid Films ◽

Theoretical Description ◽

Propagation Path ◽

Microfluidic Channels ◽

Potential Applications

Abstract 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.

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Numerical Analysis of Droplet Motion over a Flat Plate Due to Surface Acoustic Waves

Microgravity Science and Technology ◽

10.1007/s12217-020-09784-1 ◽

2020 ◽

Vol 32 (4) ◽

pp. 647-660 ◽

Cited By ~ 2

Author(s):

S. M. Sheikholeslam Noori ◽

M. Taeibi Rahni ◽

S. A. Shams Taleghani

Keyword(s):

Numerical Analysis ◽

Flat Plate ◽

Acoustic Waves ◽

Surface Acoustic Waves ◽

Droplet Motion

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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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Rapid additive-free bacteria lysis using traveling surface acoustic waves in microfluidic channels

Lab on a Chip ◽

10.1039/c9lc00656g ◽

2019 ◽

Vol 19 (24) ◽

pp. 4064-4070 ◽

Cited By ~ 4

Author(s):

Haiwei Lu ◽

Kirk Mutafopulos ◽

John A. Heyman ◽

Pascal Spink ◽

Liang Shen ◽

...

Keyword(s):

Microfluidic Device ◽

Acoustic Waves ◽

High Efficiency ◽

Surface Acoustic Waves ◽

Microfluidic Channels ◽

Wide Range

We introduce a microfluidic device that uses traveling surface acoustic waves to lyse bacteria with high efficiency. This lysis method should be applicable to a wide range of bacteria species and can be modified to analyze individual bacteria cells.

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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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Numerical analysis of two-dimensional piezoelectric waveguides for surface acoustic waves by finite-element method

Electronics Letters ◽

10.1049/el:19810428 ◽

1981 ◽

Vol 17 (17) ◽

pp. 609 ◽

Cited By ~ 2

Author(s):

M. Koshiba ◽

M. Okada ◽

M. Suzuki

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Numerical Analysis ◽

Acoustic Waves ◽

Surface Acoustic Waves ◽

Two Dimensional ◽

Element Method

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

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455417500031 ◽

2017 ◽

Vol 17 (01) ◽

pp. 1750003 ◽

Cited By ~ 1

Author(s):

S. R. Massah ◽

M. M. Torabipour

Keyword(s):

Soil Type ◽

Acoustic Waves ◽

Acoustic Pressure ◽

Impact Load ◽

Underground Structure ◽

Surface Acoustic Waves ◽

Ground Surface ◽

Sound Waves ◽

Arbitrary Location ◽

Two Parameters

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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