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Ma M, Gao H, Guo X, Su Z. Reconfigurable ultrasound focusing effect through acoustic barriers. ULTRASONICS 2024; 145:107470. [PMID: 39316886 DOI: 10.1016/j.ultras.2024.107470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 08/20/2024] [Accepted: 09/10/2024] [Indexed: 09/26/2024]
Abstract
The low transmission efficiency of ultrasonic waves in waveguides of a high acoustic impedance (referred to as dense materials), due to the impedance mismatch between the background media and the dense materials, poses a significant obstacle to practical applications of high-intensity focused ultrasound (HIFU) such as ultrasound therapy or medical imaging. To address this challenge, we present an inverse optimization scheme for fabrication of novel acoustic meta-lenses, enabling strengthened penetration and enhanced focusing of ultrasonic waves when the waves traverse barriers. Both simulation and experiment validate the effectiveness of the developed meta-lenses which are annexed to hemispherical plates, and demonstrate an enhanced transmission of the sound power by an order of magnitude compared to a scenario without the use of the meta-lens. The focal distance is reconfigurable by adjusting the geometric parameters of the meta-lenses. The proposed design philosophy is not restricted by the complexity of the target structures, and it allows the ultrasonic waves to pass through acoustic barriers with a non-uniform thickness yet maintaining efficient wave focusing. This study holds appealing applications in HIFU-enabled ultrasound imaging and therapy.
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Affiliation(s)
- Ming Ma
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region
| | - He Gao
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region.
| | - Xinze Guo
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region
| | - Zhongqing Su
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region.
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Jin J, Pei G, Ji Z, Liu X, Yan T, Li W, Suo D. Transcranial focused ultrasound precise neuromodulation: a review of focal size regulation, treatment efficiency and mechanisms. Front Neurosci 2024; 18:1463038. [PMID: 39301015 PMCID: PMC11410768 DOI: 10.3389/fnins.2024.1463038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Accepted: 08/23/2024] [Indexed: 09/22/2024] Open
Abstract
Ultrasound is a mechanical wave that can non-invasively penetrate the skull to deep brain regions to activate neurons. Transcranial focused ultrasound neuromodulation is a promising approach, with the advantages of noninvasiveness, high-resolution, and deep penetration, which developed rapidly over the past years. However, conventional transcranial ultrasound's spatial resolution is low-precision which hinders its use in precision neuromodulation. Here we focus on methods that could increase the spatial resolution, gain modulation efficiency at the focal spot, and potential mechanisms of ultrasound neuromodulation. In this paper, we summarize strategies to enhance the precision of ultrasound stimulation, which could potentially improve the ultrasound neuromodulation technic.
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Affiliation(s)
- Jie Jin
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Guangying Pei
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Zhenxiang Ji
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing, China
| | - Xinze Liu
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Tianyi Yan
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Wei Li
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Dingjie Suo
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
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Hu Y, Lin ZB, Li ZL, Peng YG, Zhu XF. Experimental investigation of acoustic moiré effect controlled by twisted bilayer gratings. ULTRASONICS 2024; 141:107338. [PMID: 38723293 DOI: 10.1016/j.ultras.2024.107338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/28/2024] [Accepted: 05/02/2024] [Indexed: 06/11/2024]
Abstract
Recently, the moiré pattern has attracted lots of attention by superimposing two planar structures of regular geometries, such as two sets of metasurfaces or gratings. Here, we show the experimental investigation of acoustic moiré effect by using twisted bilayer gratings (i.e., one grating twisted with respect to the other). We observed the guided resonance that occurred when the incident ultrasound beam was coupled with the guiding modes in a meta-grating, significantly influencing the reflection and transmission. Tunable guided resonances from the moiré effect with complete ultrasound reflection at different frequencies were further demonstrated in experiments. Combining the measurements of transmission spectra and the Fast Fourier Transform analyses, we reveal the guided resonance frequencies of moiré ultrasonic metasurface can be effectively controlled by adjusting the twisting angle of the bilayer gratings. Our results can be explained in a simplified model based on the band folding theory, providing a reliable prediction on the precise control of ultrasound reflection via the twisting angle adjustment. Our work extends the moiré metasurface from optics into acoustics, which shows more possibilities for the ultrasound beam engineering from the moiré effect and enables the exploration of functional acoustic devices for ultrasound imaging, treatment and diagnosis.
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Affiliation(s)
- Yu Hu
- School of Physics and Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zi-Bin Lin
- School of Physics and Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zong-Lin Li
- School of Physics and Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yu-Gui Peng
- School of Physics and Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Xue-Feng Zhu
- School of Physics and Innovation Institute, Huazhong University of Science and Technology, Wuhan 430074, China; Key Laboratory of Biomedical Imaging Science and System, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
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Wu Q, You B, Zhang X, Tu J. Investigation of an Active Focusing Planar Piezoelectric Ultrasonic Transducer. SENSORS (BASEL, SWITZERLAND) 2024; 24:4082. [PMID: 39000861 PMCID: PMC11244312 DOI: 10.3390/s24134082] [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: 05/17/2024] [Revised: 06/19/2024] [Accepted: 06/21/2024] [Indexed: 07/16/2024]
Abstract
Ultrasonic focusing transducers have broad prospects in advanced ultrasonic non-destructive testing fields. However, conventional focusing methods that use acoustic concave lenses can disrupt the acoustic impedance matching condition, thereby adversely affecting the sensitivity of the transducers. In this paper, an active focusing planar ultrasonic transducer is designed and presented to achieve a focusing effect with a higher sensitivity. An electrode pattern consisting of multiple concentric rings is designed, which is inspired by the structure of Fresnel Zone Plates (FZP). The structural parameters are optimized using finite element simulation methods. A prototype of the transducer is manufactured with electrode patterns made of conductive silver paste using silk screen-printing technology. Conventional focusing transducers using an acoustic lens and an FZP baffle are also manufactured, and their focusing performances are comparatively tested. The experimental results show that our novel transducer has a focal length of 16 mm and a center frequency of 1.16 MHz, and that the sensitivity is improved by 23.3% compared with the conventional focusing transducers. This research provides a new approach for the design of focusing transducers.
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Affiliation(s)
- Qiao Wu
- School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China
- Key Lab of Modern Manufacture Quality Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Bin You
- School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Xu Zhang
- School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China
- Key Lab of Modern Manufacture Quality Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Jun Tu
- School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China
- Key Lab of Modern Manufacture Quality Engineering, Hubei University of Technology, Wuhan 430068, China
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Guo L, Zhao S, Yang J, Kitipornchai S. Graphene-based phononic crystal lenses: Machine learning-assisted analysis and design. ULTRASONICS 2023; 138:107220. [PMID: 38118238 DOI: 10.1016/j.ultras.2023.107220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/12/2023] [Accepted: 12/09/2023] [Indexed: 12/22/2023]
Abstract
The advance of artificial intelligence and graphene-based composites brings new vitality into the conventional design of acoustic lenses which suffers from high computation cost and difficulties in achieving precise desired refractive indices. This paper presents an efficient and accurate design methodology for graphene-based gradient-index phononic crystal (GGPC) lenses by combing theoretical formulations and machine learning methods. The GGPC lenses consist of two-dimensional phononic crystals possessing square unit cells with graphene-based composite inclusions. The plane wave expansion method is exploited to obtain the dispersion relations of elastic waves in the structures and then establish the data sets of the effective refractive indices in structures with different volume fractions of graphene fillers in composite materials and filling fractions of inclusions. Based on the database established by the theoretical formulation, genetic programming, a superior machine learning algorithm, is introduced to generate explicit mathematical expressions to predict the effective refractive indices under different structural information. The design of GGPC lenses is conducted with the assistance of the machine learning prediction model, and it will be illustrated by several typical design examples. The proposed design method offers high efficiency, accuracy as well as the ability to achieve inverse design of GGPC lenses, thus significantly facilitating the development of novel phononic crystal lenses and acoustic energy focusing.
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Affiliation(s)
- Liangteng Guo
- School of Civil Engineering, The University of Queensland, St. Lucia, QLD 4072 Australia
| | - Shaoyu Zhao
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083 Australia
| | - Jie Yang
- School of Engineering, RMIT University, PO Box 71, Bundoora, VIC 3083 Australia.
| | - Sritawat Kitipornchai
- School of Civil Engineering, The University of Queensland, St. Lucia, QLD 4072 Australia
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Danawe H, Tol S. Broadband subwavelength imaging of flexural elastic waves in flat phononic crystal lenses. Sci Rep 2023; 13:7310. [PMID: 37147434 PMCID: PMC10163228 DOI: 10.1038/s41598-023-34314-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023] Open
Abstract
Subwavelength imaging of elastic/acoustic waves using phononic crystals (PCs) is limited to a narrow frequency range via the two existing mechanisms that utilize either the intense Bragg scattering in the first phonon band or negative effective properties (left-handed material) in the second (or higher) phonon band. In the first phonon band, the imaging phenomenon can only exist at frequencies closer to the first Bragg band gap where the equal frequency contours (EFCs) are convex. Whereas, for the left-handed materials, the subwavelength imaging is restricted to a narrow frequency region where wave vectors in PC and background material are close to each other, which is essential for single-point image formation. In this work, we propose a PC lens for broadband subwavelength imaging of flexural waves in plates exploiting the second phonon band and the anisotropy of a PC lattice for the first time. Using a square lattice design with square-shaped EFCs, we enable the group velocity vector to always be perpendicular to the lens interface irrespective of the frequency and incidence angle; thus, resulting in a broadband imaging capability. We numerically and experimentally demonstrate subwavelength imaging using this concept over a significantly broadband frequency range.
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Affiliation(s)
- Hrishikesh Danawe
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Serife Tol
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
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