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15 pages, 5380 KiB

Open AccessArticle

Miniature Ultrasonic Spatial Localization Module in the Lightweight Interactive

by Lieguang Li, Xueying Xiu, Haochen Lyu, Haolin Yang, Ahmad Safari and Songsong Zhang

Micromachines 2024, 15(1), 71; https://doi.org/10.3390/mi15010071 - 29 Dec 2023

Cited by 3 | Viewed by 1598

The advancement of spatial interaction technology has greatly enriched the domain of consumer electronics. Traditional solutions based on optical technologies suffers high power consumption and significant costs, making them less ideal in lightweight implementations. In contrast, ultrasonic solutions stand out due to their lower power consumption and cost-effectiveness, capturing widespread attention and interest. This paper addresses the challenges associated with the application of ultrasound sensors in spatial localization. Traditional ultrasound systems are hindered by blind spots, large physical dimensions, and constrained measurement ranges, limiting their practical applicability. To overcome these limitations, this paper proposes a miniature ultrasonic spatial localization module employing piezoelectric micromechanical ultrasonic transducers (PMUTs). The module is comprised of three devices each with dimension of 1.2 mm × 1.2 mm × 0.5 mm, operating at a frequency of around 180 kHz. This configuration facilitates a comprehensive distance detection range of 0–800 mm within 80° directivity, devoid of blind spot. The error rate and failure range of measurement as well as their relationship with the SNR (signal-to-noise ratio) are also thoroughly investigated. This work heralds a significant enhancement in hand spatial localization capabilities, propelling advancements in acoustic sensor applications of the meta-universe. Full article

(This article belongs to the Special Issue Design, Fabrication and Testing of MEMS/NEMS, 2nd Edition)

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12 pages, 4964 KiB

Open AccessArticle

Multiphysics Modeling and Analysis of Sc-Doped AlN Thin Film Based Piezoelectric Micromachined Ultrasonic Transducer by Finite Element Method

by Xiaonan Liu, Qiaozhen Zhang, Mingzhu Chen, Yaqi Liu, Jianqiu Zhu, Jiye Yang, Feifei Wang, Yanxue Tang and Xiangyong Zhao

Micromachines 2023, 14(10), 1942; https://doi.org/10.3390/mi14101942 - 18 Oct 2023

Cited by 10 | Viewed by 2311

Abstract

This paper presents a Piezoelectric micromechanical ultrasonic transducer (PMUT) based on a Pt/ScAlN/Mo/SiO₂/Si/SiO₂/Si multilayer structure with a circular suspension film of scandium doped aluminum nitride (ScAlN). Multiphysics modeling using the finite element method and analysis of the effect of [...] Read more.

k_{e f f}^{2}

) and the station sensitivity of the PMUT cell are performed. The calculation results show that the resonant frequency of the ScAlN-based PMUT can be above 20 MHz and its

k_{e f f}^{2}

monotonically rise with the increasing doping concentrations in ScAlN. In comparison to the pure AlN thin film-based PMUT, the static receiving sensitivity of the PMUT based on ScAlN thin film with 35% Sc doping concentration is up to 1.61 mV/kPa. Meanwhile, the static transmitting sensitivity of the PMUT is improved by 152.95 pm/V. Furthermore, the relative pulse-echo sensitivity level of the 2 × 2 PMUT array based on the Sc doping concentration of 35% AlN film is improved by 16 dB compared with that of the cell with the same Sc concentration. The investigation results demonstrate that the performance of PMUT on the proposed structure can be tunable and enhanced by a reasonable choice of the Sc doping concentration in ScAlN films and structure optimization, which provides important guidelines for the design of PMUT for practical applications. Full article

(This article belongs to the Special Issue Acoustic Transducers and Their Applications)

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11 pages, 2748 KiB

Open AccessArticle

ScAlN Film-Based Piezoelectric Micromechanical Ultrasonic Transducers with Dual-Ring Structure for Distance Sensing

by Yuchao Zhang, Bin Miao, Guanghua Wang, Hongyu Zhou, Shiqin Zhang, Yimin Hu, Junfeng Wu, Xuechao Yu and Jiadong Li

Micromachines 2023, 14(3), 516; https://doi.org/10.3390/mi14030516 - 23 Feb 2023

Cited by 7 | Viewed by 3317

Abstract

Piezoelectric micromechanical ultrasonic transducers (pMUTs) are new types of distance sensors with great potential for applications in automotive, unmanned aerial vehicle, robotics, and smart homes. However, previously reported pMUTs are limited by a short sensing distance due to lower output sound pressure. In this work, a pMUT with a special dual-ring structure based on scandium-doped aluminum nitride (ScAlN) is proposed. The combination of a dual-ring structure with pinned boundary conditions and a high piezoelectric performance ScAlN film allows the pMUT to achieve a large dynamic displacement of 2.87 μm/V and a high electromechanical coupling coefficient (

k_{t}^{2}

) of 8.92%. The results of ranging experiments show that a single pMUT achieves a distance sensing of 6 m at a resonant frequency of 91 kHz, the farthest distance sensing registered to date. This pMUT provides surprisingly fertile ground for various distance sensing applications. Full article

(This article belongs to the Topic Advances in Piezoelectric/Ultrasonic Sensors and Actuators)

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8 pages, 2297 KiB

Open AccessArticle

Fabrication and DC-Bias Manipulation Frequency Characteristics of AlN-Based Piezoelectric Micromachined Ultrasonic Transducer

by Tao Li, Le Zhang, Wenping Geng, Jian He, Yongkang Rao, Jiabing Huo, Kunxian Yan and Xiujian Chou

Micromachines 2023, 14(1), 210; https://doi.org/10.3390/mi14010210 - 14 Jan 2023

Cited by 2 | Viewed by 2469

Abstract

Due to their excellent capabilities to generate and sense ultrasound signals in an efficient and well-controlled way at the microscale, piezoelectric micromechanical ultrasonic transducers (PMUTs) are being widely used in specific systems, such as medical imaging, biometric identification, and acoustic wireless communication systems. The ongoing demand for high-performance and adjustable PMUTs has inspired the idea of manipulating PMUTs by voltage. Here, PMUTs based on AlN thin films protected by a SiO₂ layer of 200 nm were fabricated using a standard MEMS process with a resonant frequency of 505.94 kHz, a −6 dB bandwidth (BW) of 6.59 kHz, and an electromechanical coupling coefficient of 0.97%. A modification of 4.08 kHz for the resonant frequency and a bandwidth enlargement of 60.2% could be obtained when a DC bias voltage of −30 to 30 V was applied, corresponding to a maximum resonant frequency sensitivity of 83 Hz/V, which was attributed to the stress on the surface of the piezoelectric film induced by the external DC bias. These findings provide the possibility of receiving ultrasonic signals within a wider frequency range, which will play an important role in underwater three-dimensional imaging and nondestructive testing. Full article

(This article belongs to the Section E：Engineering and Technology)

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