Biosensors

Research

21 pages, 3112 KiB

Open AccessArticle

Terahertz Plasmonic Sensor Based on Metal–Insulator Composite Woven-Wire Mesh

by Ja-Yu Lu, Po-Lun Chen and Borwen You

Biosensors 2022, 12(9), 669; https://doi.org/10.3390/bios12090669 - 23 Aug 2022

Cited by 3 | Viewed by 2235

Terahertz (THz) spectroscopy has been proven as an effective detection means for the label-free and nondestructive sensing of biochemical molecules based on their unique roto-vibrational transitions. However, the conventional THz spectroscopic system is unsuitable for minute material sensing due to its far-field detection [...] Read more.

Terahertz (THz) spectroscopy has been proven as an effective detection means for the label-free and nondestructive sensing of biochemical molecules based on their unique roto-vibrational transitions. However, the conventional THz spectroscopic system is unsuitable for minute material sensing due to its far-field detection scheme, low sample amount, and lack of spectral characteristics, leading to low absorption cross-sections and sensitivity. In this study, a 3D plasmonic structure based on a metal-coated woven-wire mesh (MCWM) was experimentally and numerically demonstrated for sensing trace amounts of analytes combined with THz spectroscopy. Dual sharp spectral features were exhibited in the transmission spectrum, originating from the resonant excitation of THz surface electromagnetic modes via the aperture and periodicity of the MCWM unit cell. According to the finite element simulation, an enhanced and localized surface field was formed at THz resonant frequencies and was concentrated at the metal gaps near the periodic corrugations of the MCWM, resulting in enormous resonant dip shifts caused by the tiny variations in membrane thicknesses and refractive indices. Different types and quantities of analytes, including hydrophilic biopolymer (PAA) membrane, nonuniformly distributed microparticles to mimic macro-biomolecules or cells, and electrolyte salts of PBS, were successfully identified by the MCWM sensor with the best thickness and refractive index sensitivities approaching 8.26 GHz/μm and 547 GHz/RIU, respectively. The demonstrated detection limit of thickness and molecular concentration could respectively achieve nanometer and femtomolar scales in PAA macromolecular detection, surpassing the available metallic mesh devices. The MCWM-based sensing platform presents a rapid, inexpensive, and simple analysis method, potentially paving the way for a new generation of label-free microanalysis sensors. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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13 pages, 2772 KiB

Open AccessArticle

Data Processing of SPR Curve Data to Maximize the Extraction of Changes in Electrochemical SPR Measurements

by Suzuyo Inoue, Kenta Fukada, Katsuyoshi Hayashi and Michiko Seyama

Biosensors 2022, 12(8), 615; https://doi.org/10.3390/bios12080615 - 8 Aug 2022

Cited by 5 | Viewed by 2343

Abstract

We developed a novel measuring and data-processing method for performing electrochemical surface plasmon resonance (EC-SPR) on sensor surfaces for which detecting a specific SPR angle is difficult, such as a polymer having a non-uniform thickness with coloration. SPR measurements are used in medicine [...] Read more.

We developed a novel measuring and data-processing method for performing electrochemical surface plasmon resonance (EC-SPR) on sensor surfaces for which detecting a specific SPR angle is difficult, such as a polymer having a non-uniform thickness with coloration. SPR measurements are used in medicine and basic research as an analytical method capable of molecular detection without labeling. However, SPR is not good for detecting small molecules with small refractive index changes. The proposed EC-SPR, which combines SPR measurements with an electrochemical reaction, makes it possible to measure small molecules without increasing the number of measurement steps. A drawback of EC-SPR is that it is difficult to detect a specific SPR angle on electron mediators, and it was found that it may not be possible to capture all the features produced. The novel method we describe here is different from the conventional one in which a specific SPR angle is obtained from an SPR curve; rather, it processes the SPR curve itself and can efficiently aggregate the feature displacements in the SPR curves that are dispersed through multiple angles. As an application, we used our method to detect small concentrations of H₂O₂ (LOD 0.7 μM) and glutamate (LOD 5 μM). Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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11 pages, 2306 KiB

Open AccessCommunication

High-Sensitivity PtSe₂ Surface Plasmon Resonance Biosensor Based on Metal-Si-Metal Waveguide Structure

by Zhitao Lin, Yiqing Shu, Weicheng Chen, Yang Zhao and Jianqing Li

Biosensors 2022, 12(1), 27; https://doi.org/10.3390/bios12010027 - 6 Jan 2022

Cited by 8 | Viewed by 2566

Abstract

PtSe₂ as a novel TMDCs material is used to modify the traditional SPR biosensors to improve the performance. On this basis, this research proposes a metal-Si-metal waveguide structure to further improve the performance of the biosensor. In this study, we not only [...] Read more.

PtSe₂ as a novel TMDCs material is used to modify the traditional SPR biosensors to improve the performance. On this basis, this research proposes a metal-Si-metal waveguide structure to further improve the performance of the biosensor. In this study, we not only studied the effects of waveguide structures containing different metals on the performance of biosensor, but also discussed the performance change of the biosensor with the change of PtSe₂ thickness. After the final optimization, a BK7-Au-Si-Au-PtSe₂ (2 nm) biosensor structure achieved the highest sensitivity of 193.8°/RIU. This work provides a new development idea for the study of SPR biosensors with waveguide structures in the future. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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10 pages, 2173 KiB

Open AccessArticle

Highly Sensitive Surface Plasmon Resonance Humidity Sensor Based on a Polyvinyl-Alcohol-Coated Polymer Optical Fiber

by Ying Wang, Jingru Wang, Yu Shao, Changrui Liao and Yiping Wang

Biosensors 2021, 11(11), 461; https://doi.org/10.3390/bios11110461 - 17 Nov 2021

Cited by 18 | Viewed by 2894

Abstract

A surface-plasmon-resonance-based fiber device is proposed for highly sensitive relative humidity (RH) sensing and human breath monitoring. The device is fabricated by using a polyvinyl alcohol (PVA) film and gold coating on the flat surface of a side-polished polymer optical fiber. The thickness [...] Read more.

A surface-plasmon-resonance-based fiber device is proposed for highly sensitive relative humidity (RH) sensing and human breath monitoring. The device is fabricated by using a polyvinyl alcohol (PVA) film and gold coating on the flat surface of a side-polished polymer optical fiber. The thickness and refractive index of the PVA coating are sensitive to environmental humidity, and thus the resonant wavelength of the proposed device exhibits a redshift as the RH increases. Experimental results demonstrate an average sensitivity of 4.98 nm/RH% across an ambient RH ranging from 40% to 90%. In particular, the sensor exhibits a linear response between 75% and 90% RH, with a sensitivity of 10.15 nm/RH%. The device is suitable for human breath tests and shows an average wavelength shift of up to 228.20 nm, which is 10 times larger than that of a silica-fiber-based humidity sensor. The corresponding response and recovery times are determined to be 0.44 s and 0.86 s, respectively. The proposed sensor has significant potential for a variety of practical applications, such as intensive care and human health analysis. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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12 pages, 22549 KiB

Open AccessArticle

CH₃NH₃PbBr₃ Thin Film Served as Guided-Wave Layer for Enhancing the Angular Sensitivity of Plasmon Biosensor

by Leiming Wu, Yuanjiang Xiang and Yuwen Qin

Biosensors 2021, 11(11), 415; https://doi.org/10.3390/bios11110415 - 23 Oct 2021

Cited by 5 | Viewed by 2050

Abstract

CH₃NH₃PbBr₃ perovskite thin film is used as a guided-wave layer and coated on the surface of an Au film to form the Au-perovskite hybrid structure. Using the hybrid structure, a perovskite-based guided-wave surface plasmon resonance (GWSPR) biosensor is [...] Read more.

CH₃NH₃PbBr₃ perovskite thin film is used as a guided-wave layer and coated on the surface of an Au film to form the Au-perovskite hybrid structure. Using the hybrid structure, a perovskite-based guided-wave surface plasmon resonance (GWSPR) biosensor is proposed with high angular sensitivity. First, it is found that the electric field at the sensing interface is improved by the CH₃NH₃PbBr₃ perovskite thin film, thereby enhancing the sensitivity. The result demonstrates that the angular sensitivity of the Au-perovskite-based GWSPR biosensor is as high as 278.5°/RIU, which is 110.2% higher than that of a conventional Au-based surface plasmon resonance (SPR) biosensor. Second, the selection of the coupling prism in the configuration of the GWSPR biosensor is also analyzed, and it indicates that a low refractive index (RI) prism can generate greater sensitivity. Therefore, the low-RI BK7 prism is served as the coupling prism for the proposed GWSPR biosensor. Finally, the proposed GWSPR sensing structure can not only be used for liquid sensing, but also for gas sensing, and it has also been demonstrated that the GWSPR gas sensor is 2.8 times more sensitive than the Au-based SPR gas sensor. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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8 pages, 2259 KiB

Open AccessCommunication

Self-Referenced Refractive Index Biosensing with Graphene Fano Resonance Modes

by Xiaoyu Dai, Banxian Ruan and Yuanjiang Xiang

Biosensors 2021, 11(10), 400; https://doi.org/10.3390/bios11100400 - 17 Oct 2021

Cited by 8 | Viewed by 5133

Abstract

A hybrid structure composed of periodic monolayer graphene nanoribbons and a dielectric multilayer structure was designed to generate a Fano resonance (FR). The strong interaction between the surface plasmon resonance of graphene and the dielectric waveguide mode results in the FR. The finite [...] Read more.

A hybrid structure composed of periodic monolayer graphene nanoribbons and a dielectric multilayer structure was designed to generate a Fano resonance (FR). The strong interaction between the surface plasmon resonance of graphene and the dielectric waveguide mode results in the FR. The finite element method is utilized to investigate the behaviors of the FR, and it matches well with the theoretical calculations using rigorous coupled wave theory. The results demonstrate that the profile of the FR can be passively tuned by the period of the graphene nanoribbons and actively tuned by the Fermi level of the graphene. The decoupled nature of the FR gives it potential applications as a self-calibrated refractive index biosensor, and the sensitivity can reach as high as 4.615 μm/RIU. Thus, this work provides a new idea for an excellent self-referencing refractive index biosensor. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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11 pages, 1815 KiB

Open AccessArticle

Theoretical Model for a Highly Sensitive Near Infrared Biosensor Based on Bloch Surface Wave with Dirac Semimetal

by Qiwen Zheng, Yamei Liu, Wenguang Lu, Xiaoyu Dai, Haishan Tian and Leyong Jiang

Biosensors 2021, 11(10), 390; https://doi.org/10.3390/bios11100390 - 14 Oct 2021

Cited by 5 | Viewed by 2507

Abstract

In this work, we present a theoretical model of a near-infrared sensitive refractive index biosensor based on the truncate 1D photonic crystal (1D PC) structure with Dirac semimetal. This highly sensitive near-infrared biosensor originates from the sharp reflectance peak caused by the excitation [...] Read more.

In this work, we present a theoretical model of a near-infrared sensitive refractive index biosensor based on the truncate 1D photonic crystal (1D PC) structure with Dirac semimetal. This highly sensitive near-infrared biosensor originates from the sharp reflectance peak caused by the excitation of Bloch surface wave (BSW) at the interface between the Dirac semimetal and 1D PC. The sensitivity of the biosensor model is sensitive to the Fermi energy of Dirac semimetal, the thickness of the truncate layer and the refractive index of the sensing medium. By optimizing the structural parameters, the maximum refractive index sensitivity of the biosensor model can surpass 17.4 × 10³/RIU, which achieves a certain competitiveness compared to conventional surface plasmon resonance (SPR) or BSW sensors. Considering that bulk materials are easier to handle than two-dimensional materials in manufacturing facilities, we judge that 3D Dirac semimetal and its related devices will provide a strong competitor and alternative to graphene-based devices. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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11 pages, 1748 KiB

Open AccessArticle

High Sensitivity Terahertz Biosensor Based on Mode Coupling of a Graphene/Bragg Reflector Hybrid Structure

by Yamei Liu, Qiwen Zheng, Hongxia Yuan, Shenping Wang, Keqiang Yin, Xiaoyu Dai, Xiao Zou and Leyong Jiang

Biosensors 2021, 11(10), 377; https://doi.org/10.3390/bios11100377 - 8 Oct 2021

Cited by 7 | Viewed by 2861

Abstract

In this work, a high-sensitivity terahertz (THz) biosensor is achieved by using a graphene/Bragg reflector hybrid structure. This high-sensitivity THz biosensor is developed from the sharp Fano resonance transmission peak created by coupling the graphene Tamm plasmons (GTPs) mode to a defect mode. [...] Read more.

In this work, a high-sensitivity terahertz (THz) biosensor is achieved by using a graphene/Bragg reflector hybrid structure. This high-sensitivity THz biosensor is developed from the sharp Fano resonance transmission peak created by coupling the graphene Tamm plasmons (GTPs) mode to a defect mode. It is found that the proposed THz biosensor is highly sensitive to the Fermi energy of graphene, as well as the thickness and refractive index of the sensing medium. Through specific parameter settings, the composite structure can achieve both a liquid biosensor and a gas biosensor. For the liquid biosensor, the maximum sensitivity of

> 1000 ° / RIU

is obtained by selecting appropriate parameters. We believe the proposed layered hybrid structure has the potential to fabricate graphene-based high-sensitivity biosensors. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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10 pages, 2445 KiB

Open AccessArticle

Tunable Goos-Hänchen Shift Surface Plasmon Resonance Sensor Based on Graphene-hBN Heterostructure

by Zihao Liu, Fangyuan Lu, Leyong Jiang, Wei Lin and Zhiwei Zheng

Biosensors 2021, 11(6), 201; https://doi.org/10.3390/bios11060201 - 21 Jun 2021

Cited by 21 | Viewed by 3015

Abstract

In this paper, a bimetallic sensor based on graphene-hexagonal boron nitride (hBN) heterostructure is theoretically studied. The sensitivity of the sensor can be improved by enhancing the Goos–Hänchen (GH) shift in the infrared band. The theoretical results show that adjusting the Fermi level, [...] Read more.

In this paper, a bimetallic sensor based on graphene-hexagonal boron nitride (hBN) heterostructure is theoretically studied. The sensitivity of the sensor can be improved by enhancing the Goos–Hänchen (GH) shift in the infrared band. The theoretical results show that adjusting the Fermi level, the number of graphene layers and the thickness of hBN, a GH shift of 182.09 λ can be obtained. Moreover, sensitivity of 2.02 × 10⁵ λ/RIU can be achieved with monolayer graphene, the thickness of gold layer is 20 nm, silver layer is 15 nm, and the hBN thickness of 492 nm. This heterogeneous infrared sensor has the advantages of high sensitivity and strong stability. The research results will provide a theoretical basis for the design of a new high-sensitivity infrared band sensor. Full article

(This article belongs to the Special Issue Optical Biosensor with 2D Materials and Metamaterials)

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