Yue Wang
Huabin Wang
Inhee Maeng- 1Key Laboratory of Ultrafast Photoelectric and Terahertz Science in Shaanxi, Xi’an University of Technology, Xi’an, China
- 2Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, China
- 3Medical Convergence Research Institute, College of Medicine, Yonsei University, Seoul, South Korea
Editorial on the Research Topic
Advanced Terahertz spectrum and metamaterials for biochemical sensing and setection
Terahertz (THz) electromagnetic spectroscopy, located between microwaves and infrared radiation, is a promising analytical method for sensitive probing in a label-free and nondestructive manner [1]. THz spectrum can provide unique fingerprint information regarding various biochemical or organic molecules [2, 3], and can be used for qualitative or quantitative sensing and detection of biochemical substrates. Although the development of THz sensing and detection has been overshadowed by the great progress achieved in microwave and infrared spectroscopies, its uniquely attractive features have encouraged researchers to explore the potential of this band. However, traditional THz systems rely on bulk amounts of the analyte tablet in order to increase the interaction between THz waves and the sample, which is not in accordance with the real-world requirements for the detection of trace substrates, because the biochemical analyte is usually present in extremely low quantities.
It is notable that the collective resonances of subwavelength, periodic artificial structures have endowed THz metamaterials with local field enhancement, enhancing interactions between THz waves and the target biochemical or organic molecules [4–7]. This strategy not only provides an important method for the sensitive detection of substrates, but also facilitates the advance of THz sensing from laboratory demonstrations to practical applications [8, 9]. This Research Topic presents novel research that contributes to the design of functional THz metamaterials for sensing and detection applications, as well as spectral diagnostic techniques in the THz band. Four articles were collected and are explained below.
Shang et al. applied THz time-domain spectroscopy to study laser-induced damage of an ITO thin film. The peak-to-peak value in the time domain and the amplitude in the frequency domain for the damaged area evidently increased compared with those of the undamaged area. The increased laser-induced energy resulted in a larger damaged area and increased surface roughness, as shown in Figure 1. The variation, both in time- and frequency-domain spectra, can distinguish the type of damage on the optical thin film irradiated by a laser. This research provides a new approach for laser-induced damage identification of thin films using THz spectra.
FIGURE 1. Damage profile of an ITO thin film sample irradiated by a laser at different energy densities: (A) 1.03 J/cm2, (B) 1.28 J/cm2, (C) 1.55 J/cm2, and (D) 2.23 J/cm2.
This Research Topic also contains three articles focused on THz metamaterials. Abdulkarim et al. proposed a broadband metamaterial based on vanadium dioxide (VO2) resonators. Its absorption characteristics could be adjusted by the temperature, because of the phase change of VO2 from insulating to metallic.
In the article by Lu et al., equivalent circuit models were utilized to analyze the resonance of THz metamaterials comprised of cross rectangular, split-ring resonators. The sensing performances of the metamaterials were discussed, and the results show that they exhibited high refractive index sensitivities of 309 GHz/RIU and 730 GHz/RIU at two resonant frequencies.
Hu et al. designed a graphene-based THz metasurface sensor using an air spacer. Structural design and material selection enabled tuning of the sensor’s resonance characteristics through the dynamic electrical properties of graphene and the thickness of the air spacer. The sensitivities of the two resonance peaks reached 450 GHz/RIU and 717 GHz/RIU.
In conclusion, this Research Topic aims to contribute to the design of different types of functional THz metamaterials to achieve high sensitivity sensing and detection. Obtaining THz spectra of the sensing target by using THz time-domain spectroscopy can provide a clear understanding of the resonant mechanisms of THz metamaterials, providing a pathway for their application in the field of biochemical sensing and detection. We are grateful to the Frontiers in Physics team for technical assistance during publishing.
Author contributions
YW drafted the Editorial and led the Research Topic. All authors have made a substantial, direct, and intellectual contribution to this Research Topic.
Funding
This work has received funding in part from the Natural Science Foundation of Shaanxi Province (no. 2020JZ48), National Natural Science Foundation of China (nos 61975163, 62275215), the Youth Innovation Team of Shaanxi Universities (no. 21JP084), and Beibei District Science and Technology Agency Supported Program for Science and Technology Talents & Independent Innovation (2021-6).
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
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References
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Keywords: Terahertz, metamaterials, spectrum, biochemical, sensing
Citation: Wang Y, Wang H and Maeng I (2022) Editorial: Advanced Terahertz spectrum and metamaterials for biochemical sensing and detection. Front. Phys. 10:1088729. doi: 10.3389/fphy.2022.1088729
Received: 03 November 2022; Accepted: 15 November 2022;
Published: 30 November 2022.
Edited and reviewed by:
Dibakar Roy Chowdhury, Mahindra École Centrale College of Engineering, IndiaCopyright © 2022 Wang, Wang and Maeng. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Yue Wang, wangyue2017@xaut.edu.cn