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Wang D, Luo S, Xu KD. A Flexible Terahertz Metamaterial Sensor for Pesticide Sensing and Detection. ACS APPLIED MATERIALS & INTERFACES 2024; 16:27969-27978. [PMID: 38752539 DOI: 10.1021/acsami.4c04503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Terahertz (THz) waves have garnered significant interest across various fields, particularly in high-sensitivity sensing applications. Metamaterials can be employed in THz sensors, specifically for refractive index sensing and pesticide detection due to their high-sensitivity characteristics. In this Article, a dual-band flexible THz metamaterial sensor based on polyimide is proposed for refractive index and pesticide sensing, which is fabricated using ultraviolet (UV) lithography technology and measured by a THz time-domain spectroscope (TDS) system. The resonant frequencies of the sensor are at 0.37 and 1.13 THz, with transmission rates of 2.9% and 0.3%, respectively. With an analyte layer attached to the sensor's surface, the sensitivity of refractive index sensing can be calculated as 0.09 and 0.28 THz/RIU (refractive index unit) at the two resonant frequencies. In order to validate the exceptional pesticide sensing performance of the sensor, chlorpyrifos-methyl acetone solutions with various concentrations are added on it. Furthermore, a monolayer of graphene is coated on the sensor's surface, which is proved capable of improving pesticide sensing sensitivity at low concentrations due to strong π-π stacking interactions with π-electrons in chlorpyrifos-methyl solutions. Therefore, the graphene-coated sensor can be utilized in detecting pesticide solutions with low concentrations, and the sensor without graphene is preferred for high concentration detection. This work provides a novel option for the THz metamaterial sensor with high sensitivity covering a wide pesticide concentration range.
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Affiliation(s)
- Dongxu Wang
- School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Siyuan Luo
- Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Chengdu 610200, China
| | - Kai-Da Xu
- School of Information and Communications Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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Bao X, Yu S, Lu W, Hao Z, Yi Z, Cheng S, Tang B, Zhang J, Tang C, Yi Y. Tunable High-Sensitivity Four-Frequency Refractive Index Sensor Based on Graphene Metamaterial. SENSORS (BASEL, SWITZERLAND) 2024; 24:2658. [PMID: 38676275 PMCID: PMC11054719 DOI: 10.3390/s24082658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/18/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024]
Abstract
As graphene-related technology advances, the benefits of graphene metamaterials become more apparent. In this study, a surface-isolated exciton-based absorber is built by running relevant simulations on graphene, which can achieve more than 98% perfect absorption at multiple frequencies in the MWIR (MediumWavelength Infra-Red (MWIR) band as compared to the typical absorber. The absorber consists of three layers: the bottom layer is gold, the middle layer is dielectric, and the top layer is patterned with graphene. Tunability was achieved by electrically altering graphene's Fermi energy, hence the position of the absorption peak. The influence of graphene's relaxation time on the sensor is discussed. Due to the symmetry of its structure, different angles of light source incidence have little effect on the absorption rate, leading to polarization insensitivity, especially for TE waves, and this absorber has polarization insensitivity at ultra-wide-angle degrees. The sensor is characterized by its tunability, polarisation insensitivity, and high sensitivity, with a sensitivity of up to 21.60 THz/refractive index unit (RIU). This paper demonstrates the feasibility of the multi-frequency sensor and provides a theoretical basis for the realization of the multi-frequency sensor. This makes it possible to apply it to high-sensitivity sensors.
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Affiliation(s)
- Xu Bao
- Joint Laboratory for Extreme Conditions Matter Properties, Key Laboratory of Manufacturing Process Testing Technology of Ministry of Education, State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China; (X.B.); (W.L.)
| | - Shujun Yu
- Key Laboratory of Metallurgical Equipment and Control Technology of the Ministry of Education, Wuhan University of Science and Technology, Wuhan 430074, China; (S.Y.); (Z.H.)
| | - Wenqiang Lu
- Joint Laboratory for Extreme Conditions Matter Properties, Key Laboratory of Manufacturing Process Testing Technology of Ministry of Education, State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China; (X.B.); (W.L.)
| | - Zhiqiang Hao
- Key Laboratory of Metallurgical Equipment and Control Technology of the Ministry of Education, Wuhan University of Science and Technology, Wuhan 430074, China; (S.Y.); (Z.H.)
| | - Zao Yi
- Joint Laboratory for Extreme Conditions Matter Properties, Key Laboratory of Manufacturing Process Testing Technology of Ministry of Education, State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China; (X.B.); (W.L.)
- School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, China;
- School of Chemistry and Chemical Engineering, Jishou University, Jishou 416000, China
| | - Shubo Cheng
- School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou 434023, China;
| | - Bin Tang
- School of Microelectronics and Control Engineering, Changzhou University, Changzhou 213164, China;
| | - Jianguo Zhang
- Department of Physics, Jinzhong University, Jinzhong 030619, China;
| | - Chaojun Tang
- College of Science, Zhejiang University of Technology, Hangzhou 310023, China;
| | - Yougen Yi
- College of Physics and Electronics, Central South University, Changsha 410083, China;
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Ali W, Liu W, Liu Y, Li Z. Near-Infrared Perfect Absorption and Refractive Index Sensing Enabled by Split Ring Nanostructures. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2668. [PMID: 37836309 PMCID: PMC10574369 DOI: 10.3390/nano13192668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023]
Abstract
Plasmonic nanostructures as narrowband perfect absorbers have garnered significant attention due to their potential applications in biosensing and environment detection. This study emphasizes the investigation of arrayed split ring nanostructures within the configuration of metal-insulator-metal (MIM) multilayers, resulting in a maximum light absorption of 99.94% in the near-infrared (NIR) spectral range. The exceptional absorption efficiency of the device is attributed to the strong resonance of electric and magnetic fields arising from the Fabry-Pérot cavity resonance. The resonant peak can be flexibly tuned by engineering the dielectric layer thickness, the period, and the geometric parameter of split rings. Remarkably, the device exhibits promising capabilities in sensing, demonstrating a sensitivity of 326 nm/RIU in visible wavelengths and 504 nm/RIU in NIR wavelengths when exposed to bio-analytes with varying refractive indices. This designed nanostructure can serve as a promising candidate for biosensors or environmental detection.
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Affiliation(s)
- Wajid Ali
- Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, Hunan University, Changsha 410082, China; (W.A.)
| | - Weitao Liu
- Department of Civil, Environmental & Geomatic Engineering, University College London, London WC1E 6BT, UK
| | - Ye Liu
- Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, Hunan University, Changsha 410082, China; (W.A.)
| | - Ziwei Li
- Hunan Institute of Optoelectronic Integration, College of Materials Science and Engineering, Hunan University, Changsha 410082, China; (W.A.)
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Dai H, Li S, Dong P, Ma Y. Design of an Ultra-Wideband Transparent Wave Absorber. MATERIALS (BASEL, SWITZERLAND) 2023; 16:5962. [PMID: 37687654 PMCID: PMC10489010 DOI: 10.3390/ma16175962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/26/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023]
Abstract
In this paper, a multilayer ultra-wideband transparent metamaterial wave absorber is proposed, which has the characteristics of ultra-wideband wave absorption, light transmission and flexible bending; in addition, due to the complete symmetry of the structure, the absorber has polarization insensitivity to incident electromagnetic waves. Both simulation and experimental results show that the frequency range of the microwave absorption rate is higher than 90% between 8.7 GHz and 38.9 GHz (between which most of the absorption rate can reach more than 95%), the total bandwidth is 30.2 GHz, and the relative bandwidth is 126.9%, realizing microwave broadband absorption and covering commonly used communication frequency bands such as X-band, Ku-band, and K-band. A sample was processed and tested. The test results are in good agreement with the results of the theoretical analysis, which proves the correctness of the theoretical analysis. In addition, through the selection and oxidation of indium tin (ITO) materials, the metamaterial also has the characteristics of optical transparency and flexibility, so it has potential application value in the window radar stealth and conformal radar stealth of weapons and equipment.
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Affiliation(s)
- Huijuan Dai
- College of Electrical Engineering, Nanjing Vocational University of Industry Technology, Nanjing 210023, China
| | - Shuying Li
- College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210023, China
| | - Peng Dong
- College of Electrical Engineering, Nanjing Vocational University of Industry Technology, Nanjing 210023, China
| | - Yanqin Ma
- College of Electrical Engineering, Nanjing Vocational University of Industry Technology, Nanjing 210023, China
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Machine learning assisted hepta band THz metamaterial absorber for biomedical applications. Sci Rep 2023; 13:1792. [PMID: 36720922 PMCID: PMC9889771 DOI: 10.1038/s41598-023-29024-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 01/30/2023] [Indexed: 02/02/2023] Open
Abstract
A hepta-band terahertz metamaterial absorber (MMA) with modified dual T-shaped resonators deposited on polyimide is presented for sensing applications. The proposed polarization sensitive MMA is ultra-thin (0.061 λ) and compact (0.21 λ) at its lowest operational frequency, with multiple absorption peaks at 1.89, 4.15, 5.32, 5.84, 7.04, 8.02, and 8.13 THz. The impedance matching theory and electric field distribution are investigated to understand the physical mechanism of hepta-band absorption. The sensing functionality is evaluated using a surrounding medium with a refractive index between 1 and 1.1, resulting in good Quality factor (Q) value of 117. The proposed sensor has the highest sensitivity of 4.72 THz/RIU for glucose detection. Extreme randomized tree (ERT) model is utilized to predict absorptivities for intermediate frequencies with unit cell dimensions, substrate thickness, angle variation, and refractive index values to reduce simulation time. The effectiveness of the ERT model in predicting absorption values is evaluated using the Adjusted R2 score, which is close to 1.0 for nmin = 2, demonstrating the prediction efficiency in various test cases. The experimental results show that 60% of simulation time and resources can be saved by simulating absorber design using the ERT model. The proposed MMA sensor with an ERT model has potential applications in biomedical fields such as bacterial infections, malaria, and other diseases.
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