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Kolesnik K, Rajagopal V, Collins DJ. Optimizing coupling layer and superstrate thickness in attachable acoustofluidic devices. ULTRASONICS 2024; 137:107202. [PMID: 37979521 DOI: 10.1016/j.ultras.2023.107202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/20/2023] [Accepted: 11/11/2023] [Indexed: 11/20/2023]
Abstract
Superstrate-based acoustofluidic devices, where the fluidic elements are reversibly coupled to a transducer rather than bonded to it, offer advantages for cost, interchangeability and preventing contamination between samples. A variety of coupling materials can be used to transmit acoustic energies into attachable superstrates, though the dimensions and material composition of the system elements are not typically optimized. This work analyzes these coupling layers for bulk wavefront transmission, including water, ultrasound gel and polydimethylsiloxane (PDMS), as well as the material makeup and thickness of the superstrate component, which is commonly comprised of glass, quartz or silicon. Our results highlight the importance of coupling layer and superstrate dimensions, identifying frequencies and component thicknesses that maximize transmission efficiency. Our results indicate that superstrate thicknesses 0.55 times the acoustic wavelength result in maximal acoustic coupling. While various coupling layers and superstrate materials are capable of similar acoustic energy transmission, the inherent dimensional stability of the PDMS coupling layers, somewhat less common in superstrate work compared to liquid-based agents, presents advantages for practically maximizing acoustic efficiency.
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Affiliation(s)
- Kirill Kolesnik
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Vijay Rajagopal
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC 3010, Australia
| | - David J Collins
- Department of Biomedical Engineering, University of Melbourne, Melbourne, VIC 3010, Australia; The Graeme Clark Institute, The University of Melbourne, Parkville, VIC 3010, Australia.
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Kolesnik K, Segeritz P, Scott DJ, Rajagopal V, Collins DJ. Sub-wavelength acoustic stencil for tailored micropatterning. LAB ON A CHIP 2023; 23:2447-2457. [PMID: 37042175 DOI: 10.1039/d3lc00043e] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Acoustofluidic devices are ideal for biomedical micromanipulation applications, with high biocompatibility and the ability to generate force gradients down to the scale of cells. However, complex and designed patterning at the microscale remains challenging. In this work we report an acoustofluidic approach to direct particles and cells within a structured surface in arbitrary configurations. Wells, trenches and cavities are embedded in this surface. Combined with a half-wavelength acoustic field, together these form an 'acoustic stencil' where arbitrary cell and particle arrangements can be reversibly generated. Here a bulk-wavemode lithium niobate resonator generates multiplexed parallel patterning via a multilayer resonant geometry, where cell-scale resolution is accomplished via structured sub-wavelength microfeatures. Uniquely, this permits simultaneous manipulation in a unidirectional, device-spanning single-node field across scalable ∼cm2 areas in a microfluidic device. This approach is demonstrated via patterning of 5, 10 and 15 μm particles and 293-F cells in a variety of arrangements, where these activities are enabling for a range of cell studies and tissue engineering applications via the generation of highly complex and designed acoustic patterns at the microscale.
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Affiliation(s)
- Kirill Kolesnik
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC 3010, Victoria, Australia.
| | - Philipp Segeritz
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC 3010, Victoria, Australia.
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC 3052, Australia
| | - Daniel J Scott
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC 3052, Australia
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Vijay Rajagopal
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC 3010, Victoria, Australia.
| | - David J Collins
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC 3010, Victoria, Australia.
- The Graeme Clark Institute, The University of Melbourne, Parkville, VIC, 3010, Australia
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Joergensen JH, Bruus H. Theory and modeling of nonperturbative effects in thermoviscous acoustofluidics. Phys Rev E 2023; 107:015106. [PMID: 36797916 DOI: 10.1103/physreve.107.015106] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 12/02/2022] [Indexed: 01/26/2023]
Abstract
A theoretical model of thermal boundary layers and acoustic heating in microscale acoustofluidic devices is presented. Based on it, an iterative numerical model is developed that enables numerical simulation of nonlinear thermoviscous effects due to acoustic heating and thermal advection. Effective boundary conditions are derived and used to enable simulations in three dimensions. The theory shows how friction in the viscous boundary layers causes local heating of the acoustofluidic device. The resulting temperature field spawns thermoacoustic bulk streaming that dominates the traditional boundary-driven Rayleigh streaming at relatively high acoustic energy densities. The model enables simulations of microscale acoustofluidics with high acoustic energy densities and streaming velocities in a range beyond the reach of perturbation theory, and is relevant for design and fabrication of high-throughput acoustofluidic devices.
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Affiliation(s)
- Jonas Helboe Joergensen
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
| | - Henrik Bruus
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
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Lickert F, Bruus H, Rossi M. Constant-Power versus Constant-Voltage Actuation in Frequency Sweeps for Acoustofluidic Applications. MICROMACHINES 2022; 13:1886. [PMID: 36363908 PMCID: PMC9695504 DOI: 10.3390/mi13111886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
Supplying a piezoelectric transducer with constant voltage or constant power during a frequency sweep can lead to different results in the determination of the acoustofluidic resonance frequencies, which are observed when studying the acoustophoretic displacements and velocities of particles suspended in a liquid-filled microchannel. In this work, three cases are considered: (1) Constant input voltage into the power amplifier, (2) constant voltage across the piezoelectric transducer, and (3) constant average power dissipation in the transducer. For each case, the measured and the simulated responses are compared, and good agreement is obtained. It is shown that Case 1, the simplest and most frequently used approach, is largely affected by the impedance of the used amplifier and wiring, so it is therefore not suitable for a reproducible characterization of the intrinsic properties of the acoustofluidic device. Case 2 strongly favors resonances at frequencies yielding the lowest impedance of the piezoelectric transducer, so small details in the acoustic response at frequencies far from the transducer resonance can easily be missed. Case 3 provides the most reliable approach, revealing both the resonant frequency, where the power-efficiency is the highest, as well as other secondary resonances across the spectrum.
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Affiliation(s)
- Fabian Lickert
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
| | - Henrik Bruus
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
| | - Massimiliano Rossi
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
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Friend J, Thompson C, Chitale K, Denis M. Introduction to the special issue on the theory and applications of acoustofluidics. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:4558. [PMID: 34972297 DOI: 10.1121/10.0009056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 11/26/2021] [Indexed: 06/14/2023]
Abstract
Acoustofluidics is a burgeoning field that applies ultrasound to micro-scale to nano-scale fluidic systems. The discovery of the ability to effectively manipulate fluids and particles at small scales has yielded results that are superior to other approaches and has been built into a diverse range of research. Recasting the fundamentals of acoustics from the past to include new phenomena observed in recent years has allowed acoustical systems to impact new areas, such as drug delivery, diagnostics, and enhanced chemical processes. The contributions in this special issue address a diverse range of research topics in acoustofluidics. Topics include acoustic streaming, flows induced by bubbles, manipulation of particles using acoustic radiation forces, fluid and structural interactions, and contributions suggesting a natural limit to the particle velocity, the ability to deliver molecules to human immune T cells, and microdroplet generation via nozzle-based acoustic atomization.
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Affiliation(s)
- James Friend
- Medically Advanced Devices Lab, Center for Medical Devices, Department of Mechanical and Aerospace Engineering, Jacobs School of Engineering and Department of Surgery, School of Medicine, 9500 Gilman Drive MC0411, University of California San Diego, La Jolla, California 92093, USA
| | - Charles Thompson
- Center for Advanced Computation and Telecommunications, Department of Electrical and Computer Engineering, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA
| | - Kedar Chitale
- Vertex Cell and Gene Therapies, Vertex Pharmaceuticals, 225A Carolina Avenue, Providence, Rhode Island 02905, USA
| | - Max Denis
- Department of Mechanical Engineering, School of Engineering & Applied Sciences, University of the District of Columbia, Washington, D.C. 20008, USA
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Steckel AG, Bruus H. Numerical study of bulk acoustofluidic devices driven by thin-film transducers and whole-system resonance modes. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:634. [PMID: 34340467 DOI: 10.1121/10.0005624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
In bulk acoustofluidic devices, acoustic resonance modes for fluid and microparticle handling are traditionally excited by bulk piezoelectric (PZE) transducers. In this work, it is demonstrated by numerical simulations in three dimensions that integrated PZE thin-film transducers, constituting less than 0.1% of the bulk device, work equally well. The simulations are performed using a well-tested and experimentally validated numerical model. A water-filled straight channel embedded in a mm-sized bulk glass chip with a 1- μm-thick thin-film transducer made of Al0.6Sc0.4N is presented as a proof-of-concept example. The acoustic energy, radiation force, and microparticle focusing times are computed and shown to be comparable to those of a conventional bulk silicon-glass device actuated by a bulk lead-zirconate-titanate transducer. The ability of thin-film transducers to create the desired acoustofluidic effects in bulk acoustofluidic devices relies on three physical aspects: the in-plane-expansion of the thin-film transducer under the applied orthogonal electric field, the acoustic whole-system resonance of the device, and the high Q-factor of the elastic solid, constituting the bulk part of the device. Consequently, the thin-film device is remarkably insensitive to the Q-factor and resonance properties of the thin-film transducer.
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Affiliation(s)
- André G Steckel
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
| | - Henrik Bruus
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
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Lickert F, Ohlin M, Bruus H, Ohlsson P. Acoustophoresis in polymer-based microfluidic devices: Modeling and experimental validation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:4281. [PMID: 34241446 DOI: 10.1121/10.0005113] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/10/2021] [Indexed: 06/13/2023]
Abstract
A finite-element model is presented for numerical simulation in three dimensions of acoustophoresis of suspended microparticles in a microchannel embedded in a polymer chip and driven by an attached piezoelectric transducer at MHz frequencies. In accordance with the recently introduced principle of whole-system ultrasound resonances, an optimal resonance mode is identified that is related to an acoustic resonance of the combined transducer-chip-channel system and not to the conventional pressure half-wave resonance of the microchannel. The acoustophoretic action in the microchannel is of comparable quality and strength to conventional silicon-glass or pure glass devices. The numerical predictions are validated by acoustic focusing experiments on 5-μm-diameter polystyrene particles suspended inside a microchannel, which was milled into a polymethylmethacrylate chip. The system was driven anti-symmetrically by a piezoelectric transducer, driven by a 30-V peak-to-peak alternating voltage in the range from 0.5 to 2.5 MHz, leading to acoustic energy densities of 13 J/m3 and particle focusing times of 6.6 s.
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Affiliation(s)
- Fabian Lickert
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
| | | | - Henrik Bruus
- Department of Physics, Technical University of Denmark, DTU Physics Building 309, DK-2800 Kongens Lyngby, Denmark
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