Acoustic Resonators and Filters

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D:Materials and Processing".

Deadline for manuscript submissions: closed (28 February 2022) | Viewed by 11315

Special Issue Editor

Electronic and Computer Engineering, The Hong Kong University of Science and Technology (HKUST), Hong Kong 999077, China
Interests: acoustic resonators and filters; VHF to THz chip-scale hybrid microsystem; photonic integrated circuits

Special Issue Information

Dear Colleagues,

Acoustic devices at radio and microwave frequencies have always received broad attention from research and commercial organizations for their profound applications in signal processing and sensing. Several fundamental advantages of RF acoustic systems, including miniaturization and low loss, make them irreplaceable in the front-end of handheld equipment. Additionally, the development of micro-electro-mechanical-system (MEMS) technology offers significant advantages over macroscopic electromechanical systems regarding monolithic integration and low manufacturing costs. Piezoelectric materials are historically used for launching acoustic devices and the well-known materials are quartz, ceramic, PZT, lithium niobate, lithium tantalate, and aluminum nitride (or scandium doped). With the deploying of the fifth-generation wireless communication systems, significantly expanded capacity via accessing larger physical bandwidth and higher operating spectrum.

In addition to signal processing, acoustic resonators and filters are also essential in physical sensors, microphones, and bio-detecting just to mention a few examples. Various outstanding challenges have to be addressed before the future development of acoustic resonators and filters. Temperature compensation, larger power handling capability, tighter integration, lower power consumption, better performance, and minimum manufacturing cost are in demand to support wider application scenarios.

Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on: (1) novel designs, modeling, and fabrication of acoustic resonators and filters; (2) new development of materials or material processing techniques; (3) novel applications of acoustic devices in cross-disciplinary fields, including signal processing, sensing, imaging, and computing.

We look forward to receiving your submissions!

Dr. Yansong Yang
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • electromechanical
  • filters
  • microwave acoustics
  • microsystems
  • micromachining
  • piezoelectricity
  • resonators

Published Papers (3 papers)

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Research

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11 pages, 2495 KiB  
Article
Fractional Bandwidth up to 24% and Spurious Free SAW Filters on Bulk 15°YX-LiNbO3 Substrates Using Thickness-Modulated IDT Structures
by Zengtian Lu, Sulei Fu, Zhibin Xu, Weibiao Wang, Qiaozhen Zhang, Jianrun Zhang and Hui Zhang
Micromachines 2022, 13(3), 439; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13030439 - 14 Mar 2022
Cited by 3 | Viewed by 2402
Abstract
To cope with ubiquitous wireless connectivity and the increased and faster data delivery in 5G communication, surface acoustic wave (SAW) filters are progressively requiring wider bandwidths. Conventional bulk 15°YX-LiNbO3 substrates with a large coupling coefficient (K2) are attractive for [...] Read more.
To cope with ubiquitous wireless connectivity and the increased and faster data delivery in 5G communication, surface acoustic wave (SAW) filters are progressively requiring wider bandwidths. Conventional bulk 15°YX-LiNbO3 substrates with a large coupling coefficient (K2) are attractive for the low-cost mass production of wideband SAW filters, but these generally suffer from spurious responses, limiting their practical application. In this work, a novel and simple SAW configuration is proposed that uses thickness-modulated interdigital transducer (IDT) structures to overcome the limitations set by spurious responses. Different from the conventional design where the thicknesses of the IDT electrodes in the series and parallel resonators generally kept the same, the proposed configuration adopts IDT electrodes of different thicknesses in the series and shunt resonators to suppress or remove unwanted spurious Rayleigh modes from the filter passband. Two different ultra-wideband SAW filter designs employing thickness-modulated IDTs were designed and fabricated to validate the effective suppression of spurious modes. The SAW filters experimentally featured spurious-free responses in the passband as well as a large 3 dB fractional bandwidth (FBW) in the 18.0% and 24.1% ranges and low insertion losses below 1 dB. This work can significantly broaden the range of applications for SAW devices and can open a pathway to commercialize ultra-wideband SAW filters in 5G communication systems. Full article
(This article belongs to the Special Issue Acoustic Resonators and Filters)
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13 pages, 3690 KiB  
Article
Simulation of Onset of the Capillary Surface Wave in the Ultrasonic Atomizer
by Yu-Lin Song, Chih-Hsiao Cheng, Manoj Kumar Reddy and Md Saikhul Islam
Micromachines 2021, 12(10), 1146; https://0-doi-org.brum.beds.ac.uk/10.3390/mi12101146 - 23 Sep 2021
Cited by 2 | Viewed by 1655
Abstract
The novel drug delivery system refers to the formulations and technologies for transporting a pharmaceutical compound in the body as it is needed to safely achieve its desired therapeutic effects. In this study, the onset vibrational amplitude of capillary surface waves for ultrasonic [...] Read more.
The novel drug delivery system refers to the formulations and technologies for transporting a pharmaceutical compound in the body as it is needed to safely achieve its desired therapeutic effects. In this study, the onset vibrational amplitude of capillary surface waves for ultrasonic atomization spray is explained based on Faraday instability. Using ultrasonic frequency, the vibrational amplitude approached a critical point, and the liquid surface broke up into tiny drops. The micro-droplets were are steadily and continuously formed after the liquid feeding rate was optimized. The simulation study reported a minimum vibrational amplitude or onset value of 0.38 μm at 500 kHz frequency. The required minimum energy to atomize the drops was simulated by COMSOL Multiphysics simulation software. The simulation result agreed well with the numerical results of a subharmonic vibrational model that ocurred at 250 kHz frequency on the liquid surface. This newly designed single frequency ultrasonic atomizer showed its true physical characteristic of resonance on the fluid surface plane. Hence, this research will contribute to the future development of a single-frequency ultrasonic nebulizer and mechatronics for the generation of uniform atomized droplets. Full article
(This article belongs to the Special Issue Acoustic Resonators and Filters)
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Review

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32 pages, 8787 KiB  
Review
Current Development in Interdigital Transducer (IDT) Surface Acoustic Wave Devices for Live Cell In Vitro Studies: A Review
by Mazlee Bin Mazalan, Anas Mohd Noor, Yufridin Wahab, Shuhaida Yahud and Wan Safwani Wan Kamarul Zaman
Micromachines 2022, 13(1), 30; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13010030 - 27 Dec 2021
Cited by 24 | Viewed by 6636
Abstract
Acoustics have a wide range of uses, from noise-cancelling to ultrasonic imaging. There has been a surge in interest in developing acoustic-based approaches for biological and biomedical applications in the last decade. This review focused on the application of surface acoustic waves (SAW) [...] Read more.
Acoustics have a wide range of uses, from noise-cancelling to ultrasonic imaging. There has been a surge in interest in developing acoustic-based approaches for biological and biomedical applications in the last decade. This review focused on the application of surface acoustic waves (SAW) based on interdigital transducers (IDT) for live-cell investigations, such as cell manipulation, cell separation, cell seeding, cell migration, cell characteristics, and cell behaviours. The approach is also known as acoustofluidic, because the SAW device is coupled with a microfluidic system that contains live cells. This article provides an overview of several forms of IDT of SAW devices on recently used cells. Conclusively, a brief viewpoint and overview of the future application of SAW techniques in live-cell investigations were presented. Full article
(This article belongs to the Special Issue Acoustic Resonators and Filters)
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