Research

19 pages, 6235 KiB

Open AccessArticle

Antisymmetric Lamb Wave Simulation Study Based on Electromagnetic Acoustic Transducer with Periodic Permanent Magnets

by Lianren Du, Ruizhen Gao and Xiaojuan Jia

Sensors 2023, 23(16), 7117; https://doi.org/10.3390/s23167117 - 11 Aug 2023

Viewed by 675

Due to its multi-mode and dispersion characteristics, Lamb waves cause interference to signal processing, which profoundly limits their application in nondestructive testing. To resolve this issue, firstly, based on the traditional EMAT, a horizontal polarization periodic permanent magnet electromagnetic acoustic transducer (HP-PPM-EMAT) was [...] Read more.

Due to its multi-mode and dispersion characteristics, Lamb waves cause interference to signal processing, which profoundly limits their application in nondestructive testing. To resolve this issue, firstly, based on the traditional EMAT, a horizontal polarization periodic permanent magnet electromagnetic acoustic transducer (HP-PPM-EMAT) was proposed. A 2-D finite element model was then developed to compare magnetic flux density, Lorentz force, and signal strength between the traditional EMAT and the HP-PPM-EMAT. The simulation results show that the HP-PPM-EMAT enhances the A0 mode Lamb wave (A0 wave) and suppresses the S0 mode Lamb wave (S0 wave). Finally, the influence of structural parameters of the HP-PPM-EMAT on the total displacement amplitude ratio of A0 and S0 was investigated using orthogonal test theory, and the width of magnet units was improved based on the orthogonal test. The results show that the total displacement amplitude ratio of A0 to S0 of the improved HP-PPM-EMAT can be improved by a factor of 7.74 compared with that of the traditional Lamb wave EMAT, which can produce higher-purity A0 mode Lamb waves. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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19 pages, 3362 KiB

Open AccessArticle

Frustrated Total Internal Reflection Measurement System for Pilot Inceptor Grip Pressure

by Andrea Zanoni, Pierre Garbo, Pierangelo Masarati and Giuseppe Quaranta

Sensors 2023, 23(14), 6308; https://doi.org/10.3390/s23146308 - 11 Jul 2023

Viewed by 972

Abstract

Sensing the interaction between the pilot and the control inceptors can provide important information about the pilot’s activity during flight, potentially enabling the objective measurement of the pilot workload, the application of preventive actions against loss of situational awareness, and the identification of [...] Read more.

Sensing the interaction between the pilot and the control inceptors can provide important information about the pilot’s activity during flight, potentially enabling the objective measurement of the pilot workload, the application of preventive actions against loss of situational awareness, and the identification of the insurgence of adverse couplings with the vehicle dynamics. This work presents an innovative pressure-sensing device developed to be seamlessly integrated into the grips of conventional aircraft control inceptors. The sensor, based on frustrated total internal reflection of light, is composed of low-cost elements and can be easily manufactured to be applicable to different hand pressure ranges. The characteristics of the sensor are first demonstrated in laboratory calibration tests. Subsequently, applications in flight simulator testing are presented, focusing on the objective representation of the pilot’s instantaneous workload. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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14 pages, 4798 KiB

Open AccessArticle

Vocal Tract Resonance Detection at Low Frequencies: Improving Physical and Transducer Configurations

by Jithin Thilakan, Balamurali B.T., Sarun P.M. and Jer-Ming Chen

Sensors 2023, 23(2), 939; https://doi.org/10.3390/s23020939 - 13 Jan 2023

Viewed by 1078

Abstract

Broadband excitation introduced at the speaker’s lips and the evaluation of its corresponding relative acoustic impedance spectrum allow for fast, accurate and non-invasive estimations of vocal tract resonances during speech and singing. However, due to radiation impedance interactions at the lips at low [...] Read more.

Broadband excitation introduced at the speaker’s lips and the evaluation of its corresponding relative acoustic impedance spectrum allow for fast, accurate and non-invasive estimations of vocal tract resonances during speech and singing. However, due to radiation impedance interactions at the lips at low frequencies, it is challenging to make reliable measurements of resonances lower than 500 Hz due to poor signal to noise ratios, limiting investigations of the first vocal tract resonance using such a method. In this paper, various physical configurations which may optimize the acoustic coupling between transducers and the vocal tract are investigated and the practical arrangement which yields the optimal vocal tract resonance detection sensitivity at low frequencies is identified. To support the investigation, two quantitative analysis methods are proposed to facilitate comparison of the sensitivity and quality of resonances identified. Accordingly, the optimal configuration identified has better acoustic coupling and low-frequency response compared with existing arrangements and is shown to reliably detect resonances down to 350 Hz (and possibly lower), thereby allowing the first resonance of a wide range of vowel articulations to be estimated with confidence. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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25 pages, 1747 KiB

Open AccessArticle

Comparison of Different Cure Monitoring Techniques

by Alexander Kyriazis, Christian Pommer, David Lohuis, Korbinian Rager, Andreas Dietzel and Michael Sinapius

Sensors 2022, 22(19), 7301; https://doi.org/10.3390/s22197301 - 26 Sep 2022

Cited by 4 | Viewed by 1608

Abstract

The ability to measure the degree of cure of epoxy resins is an important prerequisite for making manufacturing processes for fibre-reinforced plastics controllable. Since a number of physical properties change during the curing reaction of epoxy resins, a wide variety of measurement methods [...] Read more.

The ability to measure the degree of cure of epoxy resins is an important prerequisite for making manufacturing processes for fibre-reinforced plastics controllable. Since a number of physical properties change during the curing reaction of epoxy resins, a wide variety of measurement methods exist. In this article, different methods for cure monitoring of epoxy resins are applied to a room-temperature curing epoxy resin and then directly compared. The methods investigated include a structure-borne sound acoustic, a dielectric, an optical and a strain-based observation method, which for the first time are measured simultaneously on one and the same resin sample. In addition, the degree of cure is determined using a kinetic resin model based on temperature measurement data. The comparison shows that the methods have considerable but well-explainable differences in their sensitivity, interference immunity and repeatability. Some measurement methods are only sensitive before and around the gel point, while the strain-based measurement method only reacts to the curing from the gel point onwards. These differences have to be taken into account when implementing a cure monitoring system. For this reason, a multi-sensor node is suitable for component-integrated curing monitoring, measuring several physical properties of the epoxy resin simultaneously. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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20 pages, 11633 KiB

Open AccessArticle

Single LED, Single PD-Based Adaptive Bayesian Tracking Method

by Duckyong Kim, Jong Kang Park and Jong Tae Kim

Sensors 2022, 22(17), 6488; https://doi.org/10.3390/s22176488 - 29 Aug 2022

Cited by 1 | Viewed by 1111

Abstract

Recently, with the growing interest in indoor location-based services, visible light positioning (VLP) systems have been extensively studied owing to their advantages of low cost, high energy efficiency, and no electromagnetic interference. However, due to structural limitations which lead to the requirement of [...] Read more.

Recently, with the growing interest in indoor location-based services, visible light positioning (VLP) systems have been extensively studied owing to their advantages of low cost, high energy efficiency, and no electromagnetic interference. However, due to structural limitations which lead to the requirement of multiple signal sources, it has been challenging to apply VLP in real-world scenarios. In this study, we propose a single LED, single PD-based tracking system that solves these problems by applying a new Bayesian method that can effectively reduce the computational burden of particle filters. The method of evaluating particle reliability developed in this work adjusts the number of particles on the fly. Using the absolute position of the single LED source, the long-term cumulative error of the inertial measurement unit can be continuously corrected. In this regard, the applicability of the VLP system can be enhanced in places where the multiple luminescent signals are hard to consistently detect. The proposed system was verified through experiments in a classroom and a corridor, and the results show an average error of less than 11 cm at travel distances of 80 to 100 m. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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9 pages, 3535 KiB

Open AccessArticle

Microsphere Coupled Off-Core Fiber Sensor for Ultrasound Sensing

by Gerard Tatel and Xiaoyi Bao

Sensors 2022, 22(14), 5328; https://doi.org/10.3390/s22145328 - 16 Jul 2022

Cited by 2 | Viewed by 1260

Abstract

A compact fiber ultrasound-sensing device comprising a commercially available Barium Titanate (BaTiO₃) glass microsphere coupled to an open cavity off-core Fabry–Perot interferometer (FPI) fiber sensor is proposed and demonstrated. The open cavity is fabricated through splicing two segments of a single [...] Read more.

A compact fiber ultrasound-sensing device comprising a commercially available Barium Titanate (BaTiO₃) glass microsphere coupled to an open cavity off-core Fabry–Perot interferometer (FPI) fiber sensor is proposed and demonstrated. The open cavity is fabricated through splicing two segments of a single mode fiber (SMF-28) at lateral offsets. The lateral offset is matched to the radius of the microsphere to maximize their coupling and allow for an increased sensing response. Furthermore, the microsphere can be moved along the open-air cavity to allow for tuning of the reflection spectrum. The multiple passes of the FPI enabled by the high refractive index microsphere results in a 40 dB enhancement of finesse and achieves broadband ultrasound sensing from 0.1–45.6 MHz driven via a piezoelectric transducer (PZT) centered at 3.7 MHz. The goal is to achieve frequency detection in the MHz range using a repeatable, cost effective, and easy to fabricate FPI sensor design. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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10 pages, 6119 KiB

Open AccessArticle

Impact of Chamber/Annealing Temperature on the Endurance Characteristic of Zr:HfO₂ Ferroelectric Capacitor

by Yejoo Choi, Changwoo Han, Jaemin Shin, Seungjun Moon, Jinhong Min, Hyeonjung Park, Deokjoon Eom, Jehoon Lee and Changhwan Shin

Sensors 2022, 22(11), 4087; https://doi.org/10.3390/s22114087 - 27 May 2022

Cited by 10 | Viewed by 3020

Abstract

The endurance characteristic of Zr-doped HfO₂ (HZO)-based metal–ferroelectric–metal (MFM) capacitors fabricated under various deposition/annealing temperatures in the atomic layer deposition (ALD) process was investigated. The chamber temperature in the ALD process was set to 120 °C, 200 °C, or 250 °C, and [...] Read more.

The endurance characteristic of Zr-doped HfO₂ (HZO)-based metal–ferroelectric–metal (MFM) capacitors fabricated under various deposition/annealing temperatures in the atomic layer deposition (ALD) process was investigated. The chamber temperature in the ALD process was set to 120 °C, 200 °C, or 250 °C, and the annealing temperature was set to 400 °C, 500 °C, 600 °C, or 700 °C. For the given annealing temperature of 700 °C, the remnant polarization (2P_r) was 17.21 µC/cm², 26.37 µC/cm², and 31.8 µC/cm² at the chamber temperatures of 120 °C, 200 °C, and 250 °C, respectively. For the given/identical annealing temperature, the largest remnant polarization (P_r) was achieved when using the chamber temperature of 250 °C. At a higher annealing temperature, the grain size in the HZO layer becomes smaller, and thereby, it enables to boost up P_r. It was observed that the endurance characteristics for the capacitors fabricated under various annealing/chamber temperatures were quite different. The different endurance characteristics are due to the oxygen and oxygen vacancies in ferroelectric films, which affects the wakeup/fatigue behaviors. However, in common, all the capacitors showed no breakdown for an externally applied pulse (up to 10⁸ cycles of the pulse). Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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13 pages, 4468 KiB

Open AccessArticle

Strain-Dependent Photoacoustic Characteristics of Free-Standing Carbon-Nanocomposite Transmitters

by Muhammad Faraz, Muhammad Awais Abbasi, Donghee Son, Changhwan Shin, Kyu-Tae Lee, Sang Min Won and Hyoung Won Baac

Sensors 2022, 22(9), 3432; https://doi.org/10.3390/s22093432 - 30 Apr 2022

Cited by 1 | Viewed by 1451

Abstract

In this paper we demonstrate strain-dependent photoacoustic (PA) characteristics of free-standing nanocomposite transmitters that are made of carbon nanotubes (CNT) and candle soot nanoparticles (CSNP) with an elastomeric polymer matrix. We analyzed and compared PA output performances of these transmitters which are prepared [...] Read more.

In this paper we demonstrate strain-dependent photoacoustic (PA) characteristics of free-standing nanocomposite transmitters that are made of carbon nanotubes (CNT) and candle soot nanoparticles (CSNP) with an elastomeric polymer matrix. We analyzed and compared PA output performances of these transmitters which are prepared first on glass substrates and then in a delaminated free-standing form for strain-dependent characterization. This confirms that the nanocomposite transmitters with lower concentration of nanoparticles exhibit more flexible and stretchable property in terms of Young’s modulus in a range of 4.08–10.57 kPa. Then, a dynamic endurance test was performed revealing that both types of transmitters are reliable with pressure amplitude variation as low as 8–15% over 100–800 stretching cycles for a strain level of 5–28% with dynamic endurance in range of 0.28–2.8%. Then, after 2000 cycles, the transmitters showed pressure amplitude variation of 6–29% (dynamic endurance range of 0.21–1.03%) at a fixed strain level of 28%. This suggests that the free-standing nanocomposite transmitters can be used as a strain sensor under a variety of environments providing robustness under repeated stretching cycles. Full article

(This article belongs to the Special Issue Novel Design and Configuration of Optical/Acoustic/Ultrasonic/Pressure Sensor and Transducer)

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