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Chen T, Jiang H, Xie K, Xia H. A Small Highly Sensitive Glucose Sensor Based on a Glucose Oxidase-Modified U-Shaped Microfiber. SENSORS (BASEL, SWITZERLAND) 2024; 24:684. [PMID: 38276375 PMCID: PMC10820248 DOI: 10.3390/s24020684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/10/2024] [Accepted: 01/14/2024] [Indexed: 01/27/2024]
Abstract
Diabetes patients need to monitor blood glucose all year round. In this article, a novel scheme is proposed for blood glucose detection. The proposed sensor is based on a U-shaped microfiber prepared using hydrogen-oxygen flame-heating technology, and then 3-aminopropyltriethoxysilane (APTES) and glucose oxidase (GOD) are successively coated on the surface of the U-shaped microfiber via a coating technique. The glucose reacts with the GOD of the sensor surface to produce gluconic acid, which changes the effective refractive index and then shifts the interference wavelength. The structure and morphology of the sensor were characterized via scanning electron microscope (SEM) and confocal laser microscopy (CLM). The experimental results show that the sensitivity of the sensor is as high as 5.73 nm/(mg/mL). Compared with the glucose sensor composed of the same material, the sensitivity of the sensor increased by 329%. The proposed sensor has a broad application prospect in blood glucose detection of diabetic patients due to the advantages of miniaturization, high sensitivity, and good stability.
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Affiliation(s)
- Tingkuo Chen
- State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;
| | - Haiming Jiang
- State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;
| | - Kang Xie
- State Key Laboratory of Precision Electronic Manufacturing Technology and Equipment, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China;
| | - Hongyan Xia
- Department of Applied Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK
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2
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Yu H, Tong Z, Zhang W, Wu M, Tao Y, Mu J. Temperature-insensitive refractive index sensor based on a spindle-shaped few-mode fiber modal interferometer. APPLIED OPTICS 2023; 62:2727-2733. [PMID: 37133112 DOI: 10.1364/ao.484634] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A designed temperature-insensitive modal interferometer for refractive index measurement based on spindle-shaped few-mode fiber (FMF) is proposed and demonstrated. The interferometer consisting of a specific length of FMF fused between two specific lengths of single-mode fibers is bent into a balloon shape and then burned by a flame into a spindle shape to sensitize. Due to the bending of the fiber, part of the light leaks from the core to the cladding and excites the higher-order modes, and the four modes in the core of FMF interfere with the higher-order modes in the cladding. Therefore, the sensor is more sensitive to the surrounding refractive index. The experimental results show that the highest sensitivity is 237.3 nm/RIU from 1.333 to 1.365. The sensor is insensitive to temperature, which solves the problem of temperature cross talk. In addition, with its advantages of a small mechanism, simple fabrication, low loss, and good mechanical strength, the proposed sensor has broad application prospects in chemical production, fuel storage, environmental monitoring, and other fields.
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3
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Ujah E, Lai M, Slaughter G. Ultrasensitive tapered optical fiber refractive index glucose sensor. Sci Rep 2023; 13:4495. [PMID: 36934144 PMCID: PMC10024692 DOI: 10.1038/s41598-023-31127-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 03/07/2023] [Indexed: 03/20/2023] Open
Abstract
Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate highly sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5-45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due to the interaction of the propagating light in the evanescent field with glucose molecules. The coating of the TOF with gold nanoparticles (AuNPs) as an active layer for glucose sensing generated LSPR through the interaction of the evanescent wave with AuNPs deposited at the tapered waist. The results indicated that the TOF (Ø = 5 µm) exhibited improved sensing performance with a sensitivity of 1265%/RIU compared to the TOF (Ø = 12 µm) at 560%/RIU towards glucose. The AuNPs were characterized using scanning electron microscopy and ultraviolent-visible spectroscopy. The AuNPs-decorated TOF (Ø = 12 µm) demonstrated a high sensitivity of 2032%/RIU toward glucose. The AuNPs-decorated TOF sensor showed a sensitivity enhancement of nearly 4 times over TOF (Ø = 12 µm) with RI ranging from 1.328 to 1.393. The fabricated TOF enabled ultrasensitive glucose detection with good stability and fast response that may lead to next-generation ultrasensitive biosensors for real-world applications, such as disease diagnosis.
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Affiliation(s)
- Erem Ujah
- Center for Bioelectronics, Old Dominion University, Norfolk, VA, 23508, USA
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, 23508, USA
| | - Meimei Lai
- Center for Bioelectronics, Old Dominion University, Norfolk, VA, 23508, USA
| | - Gymama Slaughter
- Center for Bioelectronics, Old Dominion University, Norfolk, VA, 23508, USA.
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA, 23508, USA.
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Ryu JH, Yang H, Park S, Kim S, Han K, Kim H, Cho K, Lee KB. PLC-Based Integrated Refractive Index Sensor Probe with Partially Exposed Waveguide. SENSORS 2022; 22:s22155672. [PMID: 35957229 PMCID: PMC9370853 DOI: 10.3390/s22155672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/18/2022] [Accepted: 07/26/2022] [Indexed: 11/16/2022]
Abstract
This paper proposes a simple, high-efficiency refractive index (RI) sensor, with a structure based on the planar lightwave circuit (PLC) probe type. The optical sensor has a 1 × 2 splitter structure with reference and sensing channels, each consisting of a U-shaped waveguide structure that is configured by connecting C bends. This design allows for the sensor device to have a probe structure wherein the surface interconnected with activity devices (i.e., an optical source and optical detector) is placed on one side. The reference channel is bent with a minimum optical loss, and the sensing channel has a bent structure, involving a C-bend waveguide with a maximum loss. The C-bend waveguide with a maximum loss is conformally aligned to have a trench structure with the same bending radius, designed to selectively expose the sidewall of the core layer. The local index contrast varies depending on the material in contact with the trench, resulting in a change in the optical output power of the waveguide. The sensitivity of the proposed sensor was 0 and 2070 μW/refractive index unit (RIU) for the reference and sensing channels, respectively, as the RI changed from 1.385 to 1.445 at a 1550 nm wavelength. These results suggest that the proposed structure enables efficient RI measurement through the use of a simple dip-type method.
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Wang X, Wang C, Sun X, Li X, Liu H, Sun X, Wang F, Lu X, Huang C. Locally excited surface plasmon resonance for refractive index sensing with high sensitivity and high resolution. OPTICS LETTERS 2021; 46:3625-3628. [PMID: 34329241 DOI: 10.1364/ol.432385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
An angle-interrogated surface plasmon resonance (SPR) sensor based on a prism-coupled configuration has been extensively applied in biomedicine, environment monitoring, and food safety. Yet, the low sensitivity and low spatial resolution impede its further development. In this Letter, we investigated objective-coupled locally excited SPR for refractive index (RI) sensing with high sensitivity and high resolution. Through theoretical analysis, the SPR angle was retrieved from back focal plane imaging, which was highly correlated to the RI of the surrounding medium. Experimentally, a RI sensitivity of 77.41° refractive index unit (RIU)-1 was achieved with a detection range of 0.068 RIU when using glucose solutions for the demonstration. Furthermore, we acquired the spatial resolution of the configuration being 290 nm, and the RI measurement to a polydimethylsiloxane droplet with high spatial resolution was implemented. As a result, compared with the classical prism-coupled configuration, the locally excited SPR provides a method to achieve RI sensing with high sensitivity and high resolution.
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Cano Perez JL, Gutiérrez-Gutiérrez J, Perezcampos Mayoral C, Pérez-Campos EL, Pina Canseco MDS, Tepech Carrillo L, Mayoral LPC, Vargas Treviño M, Apreza EL, Rojas Laguna R. Fiber Optic Sensors: A Review for Glucose Measurement. BIOSENSORS 2021; 11:61. [PMID: 33669087 PMCID: PMC7996499 DOI: 10.3390/bios11030061] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/20/2021] [Accepted: 02/22/2021] [Indexed: 12/27/2022]
Abstract
Diabetes mellitus is a chronic metabolic disorder, being globally one of the most deadly diseases. This disease requires continually monitoring of the body's glucose levels. There are different types of sensors for measuring glucose, most of them invasive to the patient. Fiber optic sensors have been proven to have advantages compared to conventional sensors and they have great potential for various applications, especially in the biomedical area. Compared to other sensors, they are smaller, easy to handle, mostly non-invasive, thus leading to a lower risk of infection, high precision, well correlated and inexpensive. The objective of this review article is to compare different types of fiber optic sensors made with different experimental techniques applied to biomedicine, especially for glucose sensing. Observations are made on the way of elaboration, as well as the advantages and disadvantages that each one could have in real applications.
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Affiliation(s)
- José Luis Cano Perez
- Doctorado in Biociencias, Facultad de Medicina y Cirugia, Universidad Autónoma “Benito Juárez” de Oaxaca. Ex Hacienda de Aguilera S/N, Calz. San Felipe del Agua, Oaxaca de Juárez 68120, Mexico;
| | - Jaime Gutiérrez-Gutiérrez
- Escuela de Sistemas Biologicos e Innovacion Tecnologica, Universidad Autónoma “Benito Juárez” de Oaxaca (ESBIT-UABJO), Av. Universidad S/N, Ex-Hacienda 5 Señores, Oaxaca de Juárez 68120, Mexico; (L.T.C.); (M.V.T.); (E.L.A.)
| | - Christian Perezcampos Mayoral
- Doctorado in Biociencias, Facultad de Medicina y Cirugia, Universidad Autónoma “Benito Juárez” de Oaxaca. Ex Hacienda de Aguilera S/N, Calz. San Felipe del Agua, Oaxaca de Juárez 68120, Mexico;
| | - Eduardo L. Pérez-Campos
- Facultad de Medicina y Cirugia, Universidad Autónoma “Benito Juárez” de Oaxaca. Ex Hacienda de Aguilera S/N, Calz. San Felipe del Agua, Oaxaca de Juárez 68120, Mexico; (E.L.P.-C.); (M.d.S.P.C.); (L.P.-C.M.)
| | - Maria del Socorro Pina Canseco
- Facultad de Medicina y Cirugia, Universidad Autónoma “Benito Juárez” de Oaxaca. Ex Hacienda de Aguilera S/N, Calz. San Felipe del Agua, Oaxaca de Juárez 68120, Mexico; (E.L.P.-C.); (M.d.S.P.C.); (L.P.-C.M.)
| | - Lorenzo Tepech Carrillo
- Escuela de Sistemas Biologicos e Innovacion Tecnologica, Universidad Autónoma “Benito Juárez” de Oaxaca (ESBIT-UABJO), Av. Universidad S/N, Ex-Hacienda 5 Señores, Oaxaca de Juárez 68120, Mexico; (L.T.C.); (M.V.T.); (E.L.A.)
| | - Laura Pérez-Campos Mayoral
- Facultad de Medicina y Cirugia, Universidad Autónoma “Benito Juárez” de Oaxaca. Ex Hacienda de Aguilera S/N, Calz. San Felipe del Agua, Oaxaca de Juárez 68120, Mexico; (E.L.P.-C.); (M.d.S.P.C.); (L.P.-C.M.)
| | - Marciano Vargas Treviño
- Escuela de Sistemas Biologicos e Innovacion Tecnologica, Universidad Autónoma “Benito Juárez” de Oaxaca (ESBIT-UABJO), Av. Universidad S/N, Ex-Hacienda 5 Señores, Oaxaca de Juárez 68120, Mexico; (L.T.C.); (M.V.T.); (E.L.A.)
| | - Edmundo López Apreza
- Escuela de Sistemas Biologicos e Innovacion Tecnologica, Universidad Autónoma “Benito Juárez” de Oaxaca (ESBIT-UABJO), Av. Universidad S/N, Ex-Hacienda 5 Señores, Oaxaca de Juárez 68120, Mexico; (L.T.C.); (M.V.T.); (E.L.A.)
| | - Roberto Rojas Laguna
- Division de Ingenierias, Campus Irapuato-Salamanca, Universidad de Guanajuato, Carretera Salamanca-Valle de Santiago km 3.5 + 1.8, Comunidad de Palo Blanco, Salamanca 36885, Mexico;
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Wen HY, Huang CW, Li YL, Chen JL, Yeh YT, Chiang CC. A Lamping U-Shaped Fiber Biosensor Detector for MicroRNA. SENSORS 2020; 20:s20051509. [PMID: 32182926 PMCID: PMC7085725 DOI: 10.3390/s20051509] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 12/19/2022]
Abstract
This study presents a U-shaped optical fiber developed for a facile application of microRNA detection. It is fabricated by the lamping process and packaged in a quartz tube to eliminate human negligence. In addition, silanization and electrostatic self-assembly are employed to bind gold nanoparticles and miRNA-133a probe onto the silicon dioxide of the fiber surface. For Mahlavu of hepatocellular carcinoma (HCC), detection is determined by the wavelength shift and transmission loss of a U-shaped optical fiber biosensor. The spectral sensitivity of wavelength and their coefficient of determination are found at −218.319 nm/ ng/mL and 0.839, respectively. Concurrently, the sensitivity of transmission loss and their coefficient of determination are found at 162.394 dB/ ng/mL and 0.984, respectively. A method for estimating the limit of detection of Mahlavu is at 0.0133 ng/mL. The results show that the proposed U-shaped biosensor is highly specific to miRNA-133a and possesses good sensitivity to variations in specimen concentration. As such, it could be of substantial value in microRNA detection.
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Affiliation(s)
- Hsin-Yi Wen
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, 415 Chien Kung Road, Kaohsiung 80778, Taiwan; (H.-Y.W.); (C.-W.H.); (Y.-L.L.); (J.-L.C.)
| | - Chun-Wei Huang
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, 415 Chien Kung Road, Kaohsiung 80778, Taiwan; (H.-Y.W.); (C.-W.H.); (Y.-L.L.); (J.-L.C.)
| | - Yu-Le Li
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, 415 Chien Kung Road, Kaohsiung 80778, Taiwan; (H.-Y.W.); (C.-W.H.); (Y.-L.L.); (J.-L.C.)
| | - Jing-Luen Chen
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, 415 Chien Kung Road, Kaohsiung 80778, Taiwan; (H.-Y.W.); (C.-W.H.); (Y.-L.L.); (J.-L.C.)
| | - Yao-Tsung Yeh
- Department of Medical Laboratory Science and Biotechnology, Fooyin University, Kaohsiung 83102, Taiwan;
| | - Chia-Chin Chiang
- Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, 415 Chien Kung Road, Kaohsiung 80778, Taiwan; (H.-Y.W.); (C.-W.H.); (Y.-L.L.); (J.-L.C.)
- Correspondence:
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8
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Mariani S, Paghi A, La Mattina AA, Debrassi A, Dähne L, Barillaro G. Decoration of Porous Silicon with Gold Nanoparticles via Layer-by-Layer Nanoassembly for Interferometric and Hybrid Photonic/Plasmonic (Bio)sensing. ACS APPLIED MATERIALS & INTERFACES 2019; 11:43731-43740. [PMID: 31644268 DOI: 10.1021/acsami.9b15737] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bioapplications (e.g., biosensing, drug delivery, and photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nanoassembling of a positively charged polyelectrolyte, namely, poly(allylamine hydrochloride) (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Pérot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, namely, about 4.5-fold using NaCl aqueous solutions to infiltrate the pores and 2.6-fold for unspecific bovine serum albumin (BSA) adsorption on the pore surface, respectively. Sensitivity enhancing, about 2.5-fold, is also confirmed for affinity and selective biosensing of streptavidin using a biotinylated polymer, namely, negatively charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk (using glucose aqueous solutions) and surface (due to BSA unspecific adsorption) refractive index. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nanoassembly on PSi for (i) the enhancing of the interferometric performance in (bio)sensing applications and (ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications.
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Affiliation(s)
- Stefano Mariani
- Dipartimento di Ingegneria dell'Informazione , Università di Pisa , Via G. Caruso 16 , 56122 Pisa , Italy
| | - Alessandro Paghi
- Dipartimento di Ingegneria dell'Informazione , Università di Pisa , Via G. Caruso 16 , 56122 Pisa , Italy
| | - Antonino A La Mattina
- Dipartimento di Ingegneria dell'Informazione , Università di Pisa , Via G. Caruso 16 , 56122 Pisa , Italy
| | - Aline Debrassi
- Surflay Nanotec GmbH , Max-Planck-Straße 3 , 12489 Berlin , Germany
| | - Lars Dähne
- Surflay Nanotec GmbH , Max-Planck-Straße 3 , 12489 Berlin , Germany
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell'Informazione , Università di Pisa , Via G. Caruso 16 , 56122 Pisa , Italy
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9
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Affiliation(s)
- Xu-dong Wang
- Department of Chemistry, Fudan University, 200433 Shanghai, P. R. China
| | - Otto S. Wolfbeis
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040 Regensburg, Germany
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10
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Teng C, Yu F, Deng S, Liu H, Yuan L, Zheng J, Deng H. Displacement Sensor Based on a Small U-Shaped Single-Mode Fiber. SENSORS 2019; 19:s19112531. [PMID: 31163590 PMCID: PMC6603722 DOI: 10.3390/s19112531] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 05/26/2019] [Accepted: 05/30/2019] [Indexed: 12/19/2022]
Abstract
A simple structure and easily fabricated displacement sensor was proposed and demonstrated based on a bending-induced fiber interferometer. In the design, the fiber interferometer was formed only by bending the single-mode fiber into a small U-shape without splicing, tapering, or heating pre-processing, which effectively reduces the complexity of the fabrication process, greatly enhances the mechanical strength of the sensor, and lowers the cost in the displacement sensing applications. The displacement sensing performances for the sensor with different bending radii of 3.3 mm, 4.4 mm, 5.0 mm, and 6.3 mm were investigated. Experimental results showed that the sensor had a good linear response, and for the bending radii of 3.3, 4.4, 5.0, and 6.3 mm, the proposed sensors showed high sensitivities of 134.3, 105.1, 120.9, and 144.1 pm/μm, respectively.
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Affiliation(s)
- Chuanxin Teng
- Photonics Research Centre, Guilin University of Electronic Technology, Guilin 541004, China.
- Guangxi Key Laboratory of Automatic Detection Technology and Instrument Foundation (No.), Guilin 541004, China.
| | - Fangda Yu
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Shijie Deng
- Photonics Research Centre, Guilin University of Electronic Technology, Guilin 541004, China.
| | - Houquan Liu
- Photonics Research Centre, Guilin University of Electronic Technology, Guilin 541004, China.
| | - Libo Yuan
- Photonics Research Centre, Guilin University of Electronic Technology, Guilin 541004, China.
| | - Jie Zheng
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China.
| | - Hongchang Deng
- Photonics Research Centre, Guilin University of Electronic Technology, Guilin 541004, China.
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Chiu YD, Wu CW, Chiang CC. Tilted Fiber Bragg Grating Sensor with Graphene Oxide Coating for Humidity Sensing. SENSORS 2017; 17:s17092129. [PMID: 28914768 PMCID: PMC5620546 DOI: 10.3390/s17092129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 09/08/2017] [Accepted: 09/14/2017] [Indexed: 11/16/2022]
Abstract
In this study, we propose a tilted fiber Bragg grating (TFBG) humidity sensor fabricated using the phase mask method to produce a TFBG that was then etched with five different diameters of 20, 35, 50, 55 and 60 μm, after which piezoelectric inkjet technology was used to coat the grating with graphene oxide. According to the experimental results, the diameter of 20 μm yielded the best sensitivity. In addition, the experimental results showed that the wavelength sensitivity was −0.01 nm/%RH and the linearity was 0.996. Furthermore, the measurement results showed that when the relative humidity was increased, the refractive index of the sensor was decreased, meaning that the TFBG cladding mode spectrum wavelength was shifted. Therefore, the proposed graphene oxide film TFBG humidity sensor has good potential to be an effective relative humidity monitor.
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Affiliation(s)
- Yung-Da Chiu
- Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Jiangong Rd., Sanmin Dist., Kaohsiung 807, Taiwan.
| | - Chao-Wei Wu
- Department of Aeronautical and Mechanical Engineering, Air Force Academy, Kaohsiung 807, Taiwan.
| | - Chia-Chin Chiang
- Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Jiangong Rd., Sanmin Dist., Kaohsiung 807, Taiwan.
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12
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Bent Fiber Sensor for Preservative Detection in Milk. SENSORS 2016; 16:s16122094. [PMID: 27941703 PMCID: PMC5191074 DOI: 10.3390/s16122094] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/29/2016] [Accepted: 12/06/2016] [Indexed: 11/16/2022]
Abstract
A fiber optic sensor sensitive to refractive index changes of the outer region of the fiber cladding is presented. The sensor uses bent plastic optical fibers in different bending lengths to increase sensitivity. Measurements were made for low-fat milk, the refractive index of which is altered by some preservatives such as formaldehyde, hydrogen peroxide, and sodium carbonate. Concentrations of the preservatives in the milk were changed between 0% and 14.3% while the refractive indices occurred between 1.34550 and 1.35093 for the minimum (0%) and maximum (14.286%) concentrations of sodium carbonate, respectively. Due to bending-induced sensitivity, the sensor is able to detect refractive index changes less of than 0.4%. The results show that there is excellent linearity between the concentration and normalized response of the sensor.
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