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2 pages, 157 KiB

Open AccessEditorial

Special Issue on Wireless and Passive Surface Acoustic Wave Sensor

by Wen Wang

Appl. Sci. 2023, 13(1), 589; https://doi.org/10.3390/app13010589 - 31 Dec 2022

Viewed by 1086

Abstract

The surface acoustic wave (SAW) generated by the so-called piezoelectric effect was confined to the piezoelectric substrate surface at a depth of one or two wavelengths; hence, it was very sensitive towards the external perturbations [...] Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

Research

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10 pages, 3549 KiB

Open AccessArticle

Finite Element Analysis of the Distribution Parameters of a Metal Dot Array in a SAW Gyroscope

by Hengbiao Chen, Mengjiao Lu, Lili Meng, Wen Wang and Xiuting Shao

Appl. Sci. 2022, 12(16), 8062; https://doi.org/10.3390/app12168062 - 11 Aug 2022

Cited by 3 | Viewed by 1438

Abstract

A surface acoustic wave (SAW) gyroscope has many unique advantages, but a low detection sensitivity limits its development. Previous studies have shown that adding a metal dot array to the acoustic wave propagation path of the SAW delay line can enhance the Coriolis [...] Read more.

A surface acoustic wave (SAW) gyroscope has many unique advantages, but a low detection sensitivity limits its development. Previous studies have shown that adding a metal dot array to the acoustic wave propagation path of the SAW delay line can enhance the Coriolis force and further improve sensitivity. Therefore, in order to optimize the detection sensitivity performance of the sensor, 128°YX-LiNbO₃, ST-X Quartz and X112°Y-LiTaO₃ piezoelectric substrates were selected by finite element method to analyze the influence of the metal dot array size on the SAW gyroscopic effect in this paper. The most suitable metal dot size for 128°YX-LiNbO₃ and X112°Y-LiTaO₃ obtained by simulation are

5 / 16 λ

and

1 / 16 λ

, respectively; for example, when the normalized angular velocity is 1 × 10⁻³, the SAW gyroscopic effect factor

g

of the two piezoelectric substrates distributing the optimum size metal dots can reach 22.4 kHz and 5.2 kHz. For ST-X quartz, there is a threshold between the rotation speed of the substrate and the optimum size of the metal dot. When the rotating speed is lower than the threshold, the SAW gyroscopic effect is strongest when the metal dot size is

3 / 16 λ

; otherwise, the SAW gyroscopic effect is strongest when the size is

11 / 16 λ

. These research results provide new ideas for improvement of the SAW gyroscope. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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12 pages, 4241 KiB

Open AccessArticle

Enhanced Sensitivity of FeGa Thin-Film Coated SAW Current Sensor

by Yuan Sun, Yana Jia, Yufeng Zhang, Lina Cheng, Yong Liang and Wen Wang

Appl. Sci. 2021, 11(24), 11726; https://doi.org/10.3390/app112411726 - 10 Dec 2021

Cited by 5 | Viewed by 2525

Abstract

A surface acoustic wave (SAW) device is proposed for sensing current by employing the patterned FeGa thin film as the sensitive interface. The layered media structure of FeGa/SiO₂/LiNbO₃ was established to reveal the working principle of the sensors, and an [...] Read more.

A surface acoustic wave (SAW) device is proposed for sensing current by employing the patterned FeGa thin film as the sensitive interface. The layered media structure of FeGa/SiO₂/LiNbO₃ was established to reveal the working principle of the sensors, and an SAW chip patterned by delay-line and operating at 150 MHz was fabricated photolithographically on 128° YX LiNbO₃ substrate. The FeGa thin film with a larger magnetostrictive coefficient was sputtered onto the acoustic propagation path of the SAW chip to build the sensing device. The prepared device was connected into the differential oscillation loop to construct the current sensor. The FeGa thin film produces magnetostrictive strain and so-called ΔE effect at the magnetic field generated by the applied current, which modulates the SAW propagation velocity accordingly. The differential frequency signal was collected to characterize the measurand. Larger sensitivity of 37.9 kHz/A, low hysteresis error of 0.81%, excellent repeatability and stability were achieved in the experiments from the developed sensing device. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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9 pages, 2001 KiB

Open AccessArticle

Detecting Small Size Mass Loading Using Transversely Coupled SAW Resonator

by Ran You, Jiuling Liu, Minghua Liu, Yuxiang Zhang, Zhiyuan Chen and Shitang He

Appl. Sci. 2021, 11(21), 10228; https://doi.org/10.3390/app112110228 - 1 Nov 2021

Cited by 3 | Viewed by 1741

Abstract

In the detection of small size mass loading, such as a single cell, a micro droplet or an aerosol particle, the sensors with longitudinally coupled surface acoustic wave resonator (LC-SAWR) structure can hardly avoid waveform distortions. The relative size of mass loading to [...] Read more.

In the detection of small size mass loading, such as a single cell, a micro droplet or an aerosol particle, the sensors with longitudinally coupled surface acoustic wave resonator (LC-SAWR) structure can hardly avoid waveform distortions. The relative size of mass loading to the sensitive surface of the detector is the main factor affecting the response of LC-SAWR. The smaller the relative size, the worse the waveform distortion. In order to avoid influences from the mass loading’s size, in this paper, a transversely coupled SAW resonator (TC-SAWR) was proposed in order to achieve high performance in sensing small size mass loadings. For the design and simulation of TC-SAWR, the two-dimensional coupling of model (2D-COM) theory and finite element method (FEM) were used in this work. In the experiment, SiO₂ was deposited on the sensor’s surface as a small size mass loading. The results from simulation and experiment mutually demonstrated the advantage of TC-SAWR to conquer waveform distortion in the detection of small size mass loading. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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15 pages, 7945 KiB

Open AccessArticle

An Aerosol Sensor for Multi-Sized Particles Detection Based on Surface Acoustic Wave Resonator and Cascade Impactor

by Zhiyuan Chen, Jiuling Liu, Minghua Liu, Ran You and Shitang He

Appl. Sci. 2021, 11(21), 9833; https://doi.org/10.3390/app11219833 - 21 Oct 2021

Cited by 2 | Viewed by 2458

Abstract

This research proposed the design, fabrication, and experiments of a surface acoustic wave resonator (SAWR)-based multi-sized particles monitor. A wide range selection and monitoring of large coarse particles (LCP), inhalable particles (PM₁₀), and fine inhalable particles (PM_2.5) were achieved [...] Read more.

This research proposed the design, fabrication, and experiments of a surface acoustic wave resonator (SAWR)-based multi-sized particles monitor. A wide range selection and monitoring of large coarse particles (LCP), inhalable particles (PM₁₀), and fine inhalable particles (PM_2.5) were achieved by combining high-performance 311 MHz SAWRs and a specially designed cascade impactor. This paper calculated the normalized sensitivity distribution of the chip to the mass loading effect, extracted the optimal response area for particle attachment, analyzed the influence of the distance between nozzle and chip surface on the particle distribution, and evaluated the collection efficiency of the specially designed 2 LPM (L/min) impactor through computational fluid dynamics simulation software. An experimental platform was built to conduct the response experiment of the sensor to particle-containing gas generated by the combustion of leaf fragments and repeatability test. We verified the results of the particle diameter captured at each stage. This research suggests that the sensor’s response had good linearity and repeatability, while the particles collected on the surface of the SAWR in each impactor stage met the desired diameter, observed through a microscope. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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13 pages, 3579 KiB

Open AccessArticle

A Novel Love Wave Mode Sensor Waveguide Layer with Microphononic Crystals

by Yahui Tian, Honglang Li, Wencan Chen, Zixiao Lu, Wei Luo, Xihui Mu and Litian Wang

Appl. Sci. 2021, 11(17), 8123; https://doi.org/10.3390/app11178123 - 1 Sep 2021

Cited by 7 | Viewed by 2351

Abstract

Surface acoustic wave (SAW) sensors have been applied in various areas with many advantages, such as their small size, high sensitivity and wireless and passive form. Love wave mode sensors, an important kind of SAW sensor, are mostly used in biology and chemistry [...] Read more.

Surface acoustic wave (SAW) sensors have been applied in various areas with many advantages, such as their small size, high sensitivity and wireless and passive form. Love wave mode sensors, an important kind of SAW sensor, are mostly used in biology and chemistry monitoring, as they can be used in a liquid environment. Common Love wave mode sensors consist of a delay line with waveguide and sensitive layers. To extend the application of Love wave mode sensors, this article reports a novel Love wave mode sensor consisting of a waveguide layer with microphononic crystals (PnCs). To analyze the properties of the new structure, the band structure was calculated, and transmission was obtained by introducing delay line structures and quasi-three-dimensional models. Furthermore, devices with a traditional structure and novel structure were fabricated. The results show that, by introducing the designed microstructure of phononic crystals in the waveguide layer, the attenuation was barely increased, and the frequency was shifted by a small amount. In the liquid environmental experiments, the novel structure with micro PnCs shows even better character than the traditional one. Moreover, the introduced microstructure can be extended to microreaction tanks for microcontrol. Therefore, this novel Love wave mode sensor is a promising application for combining acoustic sensors and microfluidics. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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13 pages, 5660 KiB

Open AccessArticle

Analysis and Design of Single-Phase Unidirectional Transducers with High Directivity

by Xueping Sun, Shaobo Ge, Xiuting Shao, Shun Zhou, Wen Wang, Dabin Lin and Weiguo Liu

Appl. Sci. 2021, 11(16), 7500; https://doi.org/10.3390/app11167500 - 16 Aug 2021

Cited by 3 | Viewed by 2747

Abstract

Electrode-width-controlled (EWC) single-phase unidirectional transducers (SPUDT) contribute to reduction of insertion loss of surface acoustic wave (SAW) devices due to their strong unidirectional properties. In this work, we propose a method to optimize the unidirectionality of EWC-SPUDT based on our research results that [...] Read more.

Electrode-width-controlled (EWC) single-phase unidirectional transducers (SPUDT) contribute to reduction of insertion loss of surface acoustic wave (SAW) devices due to their strong unidirectional properties. In this work, we propose a method to optimize the unidirectionality of EWC-SPUDT based on our research results that the unidirectionality of the EWC-SPUDT cell is strongly related to its reflectivity and its unidirectional angle. Furthermore, in order to ensure strong unidirectionality to achieve low insertion loss, a simulator based on the finite element method (FEM) is used to study the relationship between geometrical configuration of the EWC-SPUDT cell and its reflection coefficient, as well as its transduction coefficient. Simulation results indicate that the reflection coefficient of the optimized EWC-SPUDT cell composed of 128° YX lithium niobite (LiNbO₃) substrate and Al electrodes with thickness of 0.3μm reaches the optimal value of 5.17% when the unidirectional angle is designed to be −90°. A SAW delay line is developed with the optimized EWC-SPUDT cell without weighing, and the simulation results are verified by experiments. The experimental results show that the directivity exceeds 30 dB at the center frequency and the insertion loss is just 6.7 dB. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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10 pages, 1356 KiB

Open AccessArticle

Development of Wireless and Passive SAW Temperature Sensor with Very High Accuracy

by Xu Gao, Lina Cheng, Xufeng Xue, Shoupei Zhai, Yong Liang, Wen Wang, Mengwei Liu, Jialiang Zhu and Zhuoyue Li

Appl. Sci. 2021, 11(16), 7422; https://doi.org/10.3390/app11167422 - 12 Aug 2021

Cited by 14 | Viewed by 3538

Abstract

A surface acoustic wave (SAW) temperature sensor with high accuracy was developed and wirelessly characterized in this work. The sensing chip with reflective delay line pattern was simulated using typical coupling of modes (COM) model and prepared by the standard photolithographic technique. Sharp [...] Read more.

A surface acoustic wave (SAW) temperature sensor with high accuracy was developed and wirelessly characterized in this work. The sensing chip with reflective delay line pattern was simulated using typical coupling of modes (COM) model and prepared by the standard photolithographic technique. Sharp reflection peaks with high signal-to-noise (SNR) were observed from the developed sensing chip operating at 433 MHz. Referring to the frequency-stepped continuous wave (FSCW)-based transceiver, planar antennas, and the developed SAW chip, the wireless and passive temperature sensor system was built. Adaptive Least Mean Square (LMS) algorithm was used for the first time in the SAW sensor signal processing to significantly improve the system SNR, and the corresponding phase fluctuation is down to only 3

^{°}

. High temperature sensitivity of 36.5

^{°}

C and very high accuracy of ±0.2

^{°}

C in the range of −30

^{°}

C∼100

^{°}

C were achieved successfully by wireless measurement. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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7 pages, 2851 KiB

Open AccessArticle

Investigation of Electro-Elastic Properties for LN Single Crystals at Low Temperature

by Feifei Chen, Chao Jiang, Fapeng Yu, Xiufeng Cheng and Xian Zhao

Appl. Sci. 2021, 11(16), 7374; https://doi.org/10.3390/app11167374 - 11 Aug 2021

Cited by 2 | Viewed by 2128

Abstract

Lithium niobate crystals (LiNbO₃, LN) are multifunctional crystal materials with many outstanding properties. In this work, the electro-elastic properties of LN single crystals were explored at temperatures from −150 °C to 150 °C. The temperature dependences of dielectric permittivities, elastic compliances, [...] Read more.

Lithium niobate crystals (LiNbO₃, LN) are multifunctional crystal materials with many outstanding properties. In this work, the electro-elastic properties of LN single crystals were explored at temperatures from −150 °C to 150 °C. The temperature dependences of dielectric permittivities, elastic compliances, electromechanical coupling factors and piezoelectric coefficients were determined using the impedance method. The LN crystals possessed large dielectric permittivities, the

ε_{11}^{T} / ε_{0}

and

ε_{33}^{T} / ε_{0}

were 83.2 and 29.4 at room temperature, respectively. The elastic compliances s₁₁, s₁₃, s₃₃ and s₄₄ presented a positive increase as the temperature increased, and the variations were 5.0%, 8.2%, 4.6% and 5.4%, respectively, showing a good temperature stability. Moreover, the temperature dependence of the electromechanical coupling factors and piezoelectric coefficients for different vibration modes were studied with a temperature range from −150 °C to 150 °C, where the thickness shear vibration mode d₁₅ presented a large piezoelectric response and minimal temperature variation. Full article

(This article belongs to the Special Issue Wireless and Passive Surface Acoustic Wave Sensor)

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