The Peculiarities of the Acoustic Waves of Zero-Order Focusing in Lithium Niobate Plate

Kuznetsova, I. E.; Nedospasov, Ilya; Smirnov, Andrey; Анисимкин, В. И.; Рощупкин, Д. В.; Signore, M.A.; Francioso, Luca; Kondoh, Jun; Serebrov, M.M.; Кашин, В. В.; Kolesov, Vladimir

doi:10.3390/s21124000

Cited by 4 publications

(1 citation statement)

References 39 publications

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“…Other, less common IDT designs, including tapered IDT (TIDT) structures [16] (see figure 1(d)), chirp IDTs [17] (see figure 1(e)), and spiral IDTs [18] (see figure 1(f)), for example, are also of great interest for specific acoustofluidic applications. The slowness curve, an inverse of the speed of the SAW propagating across the substrate, may also be used to devise [19] a desired amplitude distribution in a laterally focused, relatively small region. All of these designs, with the exception of the spiral, have parallels in SAW-based telecommunication devices.…”

Section: Introductionmentioning

confidence: 99%

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

Zhang

Horesh

Floer

et al. 2021

J. Micromech. Microeng.

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Surface acoustic waves (SAW) have underpinned many acoustofluidic applications. But the typical straight, full-width interdigital transducers used to generate these waves are problematic. Fresnel diffraction of the propagating SAW causes strong nonuniformity in the wave's amplitude as it propagates across the substrate, leading to flow variations, recirculation, and peculiar wetting phenomena in fluids driven by such waves. These have led to many research projects and publications, but, ultimately, uniform fluid flow from SAW-driven streaming remains elusive. By adopting a form of apodization, the shaping of the IDT, we demonstrate the ability to produce laterally uniform SAW for acoustofluidics. Unlike traditional apodization, which shapes the IDT to produce a desired electrical signal, this new approach-unapodization-instead inverts the governing equations to produce a desired spatial distribution of SAW at a defined position along the propagation direction of the SAW. Theoretical analysis and experiment demonstrate a 50% improvement in the SAW uniformity over a straight IDT for three example unapodized designs, all while maintaining the same frequency, input power, quality factor, and electromechanical coupling. The sole downside is a 50% increase in IDT area to accommodate the unapodization. A design tool is provided with tabulated unapodized IDT configurations. To illustrate the potential of unapodization in acoustofluidics, the irregular dewetting and anomalous flows of a thin fluid film induced by traditional straight IDT SAW devices is shown to become regular and uniform with the adoption of unapodized SAW devices.

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Section: Introductionmentioning

confidence: 99%

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

Zhang

Horesh

Floer

et al. 2021

J. Micromech. Microeng.

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Design of interdigitated transducers for acoustofluidic applications

Song

Wang

Zhou

et al. 2022

Nanotechnology and Precision Engineering

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Interdigitated transducers (IDTs) were originally designed as delay lines for radars. Half a century later, they have found new life as actuators for microfluidic systems. By generating strong acoustic fields, they trigger nonlinear effects that enable pumping and mixing of fluids, and moving particles without contact. However, the transition from signal processing to actuators comes with a range of challenges concerning power density and spatial resolution that have spurred exciting developments in solid-state acoustics and especially in IDT design. Assuming some familiarity with acoustofluidics, this paper aims to provide a tutorial for IDT design and characterization for the purpose of acoustofluidic actuation. It is targeted at a diverse audience of researchers in various fields, including fluid mechanics, acoustics, and microelectronics.

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Sensitivity of acoustofluidic particle manipulation to microchannel height in standing surface acoustic wave-based microfluidic devices

Li,

Liang,

Kabla

et al. 2023

Physics of Fluids

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In this paper, the flow and particle trajectories, induced by standing surface acoustic waves (SSAWs) in a poly-dimethylsiloxane microchannel, are investigated by establishing a two-dimensional cross-sectional model with the finite element method and improved boundary conditions. Extensive parametric studies are conducted regarding the channel height, ranging from 0.2 to 4.0 times the spacing of the repetitive vertical interference pattern, to investigate its influences on the flow field and microparticle aggregation. The first-order flow field is found to be related to the channel height, exhibiting a periodic spatial distribution and oscillatory variation in its amplitude as the height changes. We theoretically analyze the propagation mechanism of the acoustic waves in the vertical direction and thus determine the periodicity of the wave interference pattern. Furthermore, we find that the speed of the particle aggregation is a function of the channel height, so the channel height can be optimized to maximize the strength of the first-order flow field and thus minimize the time of particle aggregation. The optimum heights can reduce the aggregation time by up to 76%. In addition, the acoustophoretic motions of microparticles exhibit a spatially dependent pattern when the channel height becomes larger than a quarter of the wavelength of the SAW, which can be explained by the change in the ratio between the radiation force and the streaming drag force from position to position. Our findings provide guidelines to the design and optimization of SSAW-based acoustofluidic devices.

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The Peculiarities of the Acoustic Waves of Zero-Order Focusing in Lithium Niobate Plate

Cited by 4 publications

References 39 publications

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

Unapodization: a method to produce laterally uniform surface acoustic waves for acoustofluidics

Design of interdigitated transducers for acoustofluidic applications

Sensitivity of acoustofluidic particle manipulation to microchannel height in standing surface acoustic wave-based microfluidic devices

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