Sensing and Nondestructive Testing Applications of Terahertz Spectroscopy and Imaging Systems: State-of-the-Art and State-of-the-Practice

Nsengiyumva, Walter; Zhong, Shuncong; Zheng, Longhui; Liang, Wei; Wang, Bing; Huang, Yi; Chen, Xuefeng; Shen, Yaochun

doi:10.1109/tim.2023.3318676

Cited by 17 publications

(2 citation statements)

References 637 publications

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“…Based on the good penetration ability of THz in most non-polar materials, the use of THz for the non-destructive testing of multi-layer lightweight composites is an effective technical method for ensuring product quality and safety [3][4][5]. THz non-destructive testing has emerged as a cutting-edge technique capable of identifying specific defects by examining diverse spectral features within the THz wavelength range [6][7][8]. Previous studies, such as those by H. Jiang et al, utilized three feature parameters, namely, the maximum absolute value, the signal power, and the envelope area, to image mid-gap defects of various shapes [9].…”

Section: Introductionmentioning

confidence: 99%

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Zhang,

Li,

Zhang

et al. 2024

Materials

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Multi-layer lightweight composite structures are widely used in the field of aviation and aerospace during the processes of manufacturing and use, and, as such, they inevitably produce defects, damage, and other quality problems, creating the need for timely non-destructive testing procedures and the convenient repair or replacement of quality problems related to the material. When using terahertz non-destructive testing technology to detect defects in multi-layer lightweight composite materials, due to the complexity of their structure and defect types, there are many signal characteristics of terahertz waves propagating in the structures, and there is no obvious rule behind them, resulting in a large gap between the recognition results and the actual ones. In this study, we introduced a U-Net-BiLSTM network that combines the strengths of the U-Net and BiLSTM networks. The U-Net network extracts the spatial features of THz signals, while the BiLSTM network captures their temporal features. By optimizing the network structure and various parameters, we obtained a model tailored to THz spectroscopy data. This model was subsequently employed for the identification and quantitative analysis of defects in multi-layer lightweight composite structures using THz non-destructive testing. The proposed U-Net-BiLSTM network achieved an accuracy of 99.45% in typical defect identification, with a comprehensive F1 score of 99.43%, outperforming the CNN, ResNet, U-Net, and BiLSTM networks. By leveraging defect classification and thickness recognition, this study successfully reconstructed three-dimensional THz defect images, thereby realizing quantitative defect detection.

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Section: Introductionmentioning

confidence: 99%

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Zhang,

Li,

Zhang

et al. 2024

Materials

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“…THz waves, which lie between millimeter waves and infrared light, possess distinctive characteristics that render them widely used in diverse applications such as security checks, imaging, and wireless communication [1][2][3]. The THz source is a crucial component of THz technology.…”

Section: Introductionmentioning

confidence: 99%

Circularly Polarized Ultra-Wideband Antenna for Uni-Traveling-Carrier Photodiode Terahertz Source

Li,

Nie,

Liu

et al. 2023

Sensors

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This paper proposes a circularly polarized ultra-wideband (UWB) antenna for a Uni-Traveling-Carrier Photodiode (UTC-PD) to meet the growing demand for bandwidth and polarization diversity in terahertz (THz) communication. In the design of the UTC-PD integrated antenna, the planar electrodes of the chip are directly integrated with the antenna to simplify the integration process. However, this integration introduces new problems, such as asymmetry inside the spiral antenna, which leads to a deterioration in the corresponding high-frequency performance. To address this issue, the antenna’s structure is optimized, and a lens is integrated to enhance directivity and eliminate surface waves. As a result, the proposed antenna achieves a 100–1500 GHz (175%) impedance bandwidth and a 150–720 GHz (131%) axial ratio bandwidth for the UTC-PD. The maximum gain of the antenna is 21.05 dBi at 1 THz.

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Terahertz Metamaterial Sensors: Design Theory, Optimization Approach, and Advancements in Biosensing Applications

Cao,

Jia,

Meng

et al. 2024

Adv Materials Technologies

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Metamaterials (MMs), distinguished by their unique electromagnetic properties, offer significant advantages in the realm of terahertz (THz) biosensing and early disease diagnosis. The intense electric field confined within subwavelength volumes in metallic MMs enhances the interaction between light and analytes. The Q‐factor, sensitivity and figure of merit (FOM) are three critical direct parameters for quantitative evaluation of sensor performance. Researchers are pursuing enhancement of these parameters by optimal design of MMs structures and dimensions as well as proper choice of materials. Recently, dielectric perturbation theory is quantitatively calculated and successfully utilized in the design and optimization of THz MMs sensors. Guided by this theory, this review focuses on the design principle of THz MMs sensors, the various study on how to improve the fundamental parameters of THz MMs sensors, the specific application in biosensing including the functionalization process, and the fabrication of THz MMs sensors. Based on these methods and results, the future development of THz sensors is finally presented in a perspective view.

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Sensing and Nondestructive Testing Applications of Terahertz Spectroscopy and Imaging Systems: State-of-the-Art and State-of-the-Practice

Cited by 17 publications

References 637 publications

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Quantitative Detection of Defects in Multi-Layer Lightweight Composite Structures Using THz-TDS Based on a U-Net-BiLSTM Network

Circularly Polarized Ultra-Wideband Antenna for Uni-Traveling-Carrier Photodiode Terahertz Source

Terahertz Metamaterial Sensors: Design Theory, Optimization Approach, and Advancements in Biosensing Applications

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