Submit to Sensors Review for Sensors Propose a Special Issue

Journal Browser

► Journal Browser

Fiber Optic Sensors and Applications

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (29 February 2020) | Viewed by 47504

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special issue Fiber Optic Sensors and Applications book cover image

Share This Special Issue

Special Issue Editors

Prof. Dr. Swee Chuan Tjin

E-Mail Website
Guest Editor

School of Electrical and Electronics Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
Interests: fibre optic sensors; biomedical engineering and biophotonics
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Lei Wei

E-Mail Website
Guest Editor

School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore
Interests: fiber sensors; multifunctional fibers; fiber-based wearable electronics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue focusses on all aspects of the recent research and development related to fibre optic sensors. The recent advances in fiber-based sensing technologies have enabled both fundamental studies and a wide spectrum of applications. The goal of this special issue is to bring attention to the most recent results in the field of fiber optic sensors, including new mechanisms, materials, processes and applications. Contributions on applications of novel or existing fibre optic sensors are also welcome, especially highlighting the opportunities offered by the unique features in optical fibres, or the advantages of fibre sensor configuration with respect to current technologies.

Relevant topics include, but are not limited to:

Advanced fibre design and fabrication for sensing applications.
Fibre sensors for mechanical, chemical, environmental, biological and medical applications.
Applications in industrial, life sciences, oil and gas, civil engineering, materials and defence.
Micro- and nano-structured fibre sensors.
Fibre lasers for sensing applications.
Distributed sensing.
Sensor integration and data fusion, network architectures, packaging, and long-term reliability.
Lab-on-fibres.
AI-enabled fibre optic sensing and data processing.

Prof. Dr. Swee Chuan Tjin
Prof. Dr. Lei Wei
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

fiber optic sensors
fabrication of fiber sensors
fiber lasers
multifunctional sensors
biophotonics
sensing systems
sensing signal and data processing

Published Papers (14 papers)

Download All Papers

Editorial

Jump to: Research, Review

4 pages, 172 KiB

Open AccessEditorial

Special Issue “Fiber Optic Sensors and Applications”: An Overview

by Lei Wei and Swee Chuan Tjin

Sensors 2020, 20(12), 3400; https://0-doi-org.brum.beds.ac.uk/10.3390/s20123400 - 16 Jun 2020

Cited by 5 | Viewed by 2059

Abstract

We present here the recent advance in exploring new detection mechanisms, materials, processes, and applications of fiber optic sensors. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

Research

Jump to: Editorial, Review

8 pages, 3241 KiB

Open AccessArticle

High-Sensitivity, Large Dynamic Range Refractive Index Measurement Using an Optical Microfiber Coupler

by Jiajia Wang, Xiong Li, Jun Fu and Kaiwei Li

Sensors 2019, 19(23), 5078; https://0-doi-org.brum.beds.ac.uk/10.3390/s19235078 - 21 Nov 2019

Cited by 10 | Viewed by 2559

Abstract

Wavelength tracking methods are widely employed in fiber-optic interferometers, but they suffer from the problem of fringe order ambiguity, which limits the dynamic range within half of the free spectral range. Here, we propose a new sensing strategy utilizing the unique property of the dispersion turning point in an optical microfiber coupler mode interferometer. Numerical calculations show that the position of the dispersion turning point is sensitive to the ambient refractive index, and its position can be approximated by the dual peaks/dips that lay symmetrically on both sides. In this study, we demonstrate the potential of this sensing strategy, achieving high sensitivities of larger than 5327.3 nm/RIU (refractive index unit) in the whole refractive index (RI) range of 1.333–1.4186. This sensor also shows good performance in narrow RI ranges with high resolution and high linearity. The resolution can be improved by increasing the length of the coupler. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

26 pages, 8045 KiB

Open AccessArticle

An Intra-Oral Optical Sensor for the Real-Time Identification and Assessment of Wine Intake

by Paul Faragó, Ramona Gălătuș, Sorin Hintea, Adina Bianca Boșca, Claudia Nicoleta Feurdean and Aranka Ilea

Sensors 2019, 19(21), 4719; https://0-doi-org.brum.beds.ac.uk/10.3390/s19214719 - 30 Oct 2019

Cited by 8 | Viewed by 3859

Abstract

Saliva has gained considerable attention as a diagnostics alternative to blood analyses. A wide spectrum of salivary compounds is correlated to blood concentrations of biomarkers, providing informative and discriminative data regarding the state of health. Intra-oral detection and assessment of food and beverage intake can be correlated and provides valuable information to forecast the formation and modification of salivary biomarkers. In this context, the present work proposes a novel intra-oral optical fiber sensor, developed around an optical coupler topology, and exemplified on the detection and assessment of wine intake, which is accounted for example for the formation of N^ε-carboxymethyllysine Advanced Glycation End-products. A laboratory proof of concept validates the proposed solution on four white and four red wine samples. The novel optical sensor geometry shows good spectral properties, accounting for selectivity with respect to grape-based soft drinks. This enables intra-oral detection and objective quality assessment of wine. Moreover, its implementation exploits the advantages of fiber-optics sensing and facilitates integration into a mouthguard, holding considerable potential for real-time biomedical applications to investigate Advanced Glycation End-products in the saliva and their connection with consumption of wine, for the evaluation of risk factors in diet-related diseases. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

15 pages, 2134 KiB

Open AccessArticle

Laser-Induced Deposition of Carbon Nanotubes in Fiber Optic Tips of MMI Devices

by Natanael Cuando-Espitia, Juan Bernal-Martínez, Miguel Torres-Cisneros and Daniel May-Arrioja

Sensors 2019, 19(20), 4512; https://0-doi-org.brum.beds.ac.uk/10.3390/s19204512 - 17 Oct 2019

Cited by 3 | Viewed by 2406

Abstract

The integration of carbon nanotubes (CNTs) into optical fibers allows the application of their unique properties in robust and versatile devices. Here, we present a laser-induced technique to obtain the deposition of CNTs onto the fiber optics tips of multimode interference (MMI) devices. An MMI device is constructed by splicing a section of no-core fiber (NCF) to a single-mode fiber (SMF). The tip of the MMI device is immersed into a liquid solution of CNTs and laser light is launched into the MMI device. CNTs solutions using water and methanol as solvents were tested. In addition, the use of a polymer dispersant polyvinylpyrrolidone (PVP) in the CNTs solutions was also studied. We found that the laser-induced deposition of CNTs performed in water-based solutions generates non-uniform deposits. On the other hand, the laser-induced deposition performed with methanol solutions generates uniform deposits over the fiber tip when no PVP is used and deposition at the center of the fiber when PVP is present in the CNTs solution. The results show the crucial role of the solvent on the spatial features of the laser-induced deposition process. Finally, we register and study the reflection spectra of the as-fabricated CNTs deposited MMI devices. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

12 pages, 5334 KiB

Open AccessArticle

Fiber Link Health Detection and Self-Healing Algorithm for Two-Ring-Based RoF Transport Systems

by Wen-Shing Tsai, Ching-Hung Chang, Zhin-Guei Lin, Dong-Yi Lu and Tsung-Ying Yang

Sensors 2019, 19(19), 4201; https://0-doi-org.brum.beds.ac.uk/10.3390/s19194201 - 27 Sep 2019

Cited by 5 | Viewed by 2154

Abstract

A two-ring-based radio over fiber (RoF) transport system with a two-step fiber link failure detection and self-healing algorithm is proposed to ensure quality of service (QoS) by automatically monitoring the health of each fiber link in the transport system and by resourcefully detecting, locating, and bypassing the blocked fiber links. With the assistance of the fiber Bragg grating remote sensing technique, preinstalled optical switches, and novel single-line bidirectional optical add/drop multiplexers, the optical routing pathways in the RoF transport system can be dynamically adjusted by the proposed algorithm when some fiber links are broken. Simulation results show that except in some extreme situations, the proposed algorithm can find the blocked fiber links in the RoF transport system and animatedly adjust the status of preinstalled optical switches to restore all blocked network connections, thereby ensuring QoS in the proposed RoF transport system. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

14 pages, 4446 KiB

Open AccessArticle

Design and Implementation of a Novel Measuring Scheme for Fiber Interferometer Based Sensors

by Chao-Tsung Ma, Cheng-Ling Lee and Yan-Wun You

Sensors 2019, 19(19), 4080; https://0-doi-org.brum.beds.ac.uk/10.3390/s19194080 - 21 Sep 2019

Cited by 3 | Viewed by 2534

Abstract

This paper presents a novel measuring scheme for fiber interferometer (FI) based sensors. With the advantages of being small sizes, having high sensitivity, a simple structure, good durability, being easy to integrate fiber optic communication and having immunity to electromagnetic interference (EMI), FI based sensing devices are suitable for monitoring remote system states or variations in physical parameters. However, the sensing mechanism for the interference spectrum shift of FI based sensors requires expensive equipment, such as a broadband light source (BLS) and an optical spectrum analyzer (OSA). This has strongly handicapped their wide application in practice. To solve this problem, we have, for the first time, proposed a smart measuring scheme, in which a commercial laser diode (LD) and a photodetector (PD) are used to detect the equivalent changes of optical power corresponding to the variation in measuring parameters, and a signal processing system is used to analyze the optical power changes and to determine the spectrum shifts. To demonstrate the proposed scheme, a sensing device on polymer microcavity fiber Fizeau interferometer (PMCFFI) is taken as an example for constructing a measuring system capable of long-distance monitoring of the temperature and relative humidity. In this paper, theoretical analysis and fundamental tests have been carried out. Typical results are presented to verify the feasibility and effectiveness of the proposed measuring scheme, smartly converting the interference spectrum shifts of an FI sensing device into the corresponding variations of voltage signals. With many attractive features, e.g., simplicity, low cost, and reliable remote-monitoring, the proposed scheme is very suitable for practical applications. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

10 pages, 1483 KiB

Open AccessArticle

Nonlinearity Correction in OFDR System Using a Zero-Crossing Detection-Based Clock and Self-Reference

by Shiyuan Zhao, Jiwen Cui and Jiubin Tan

Sensors 2019, 19(17), 3660; https://0-doi-org.brum.beds.ac.uk/10.3390/s19173660 - 22 Aug 2019

Cited by 24 | Viewed by 3447

Abstract

Tuning nonlinearity of the laser is the main source of deterioration of the spatial resolution in optical frequency-domain reflectometry (OFDR) system. In this paper, we develop methods for tuning nonlinearity correction in an OFDR system from the aspect of data acquisition and post-processing. An external clock based on a zero-crossing detection is researched and implemented using a customized circuit. Equal-spacing frequency sampling is, therefore, achieved in real-time. The zero-crossing detection for the beating frequency of 20 MHz is achieved. The maximum sensing distance can reach the same length of the auxiliary interferometer. Moreover, a nonlinearity correction method based on the self-reference method is proposed. The auxiliary interferometer is no longer necessary in this scheme. The tuning information of the laser is extracted by a strong reflectivity point at the end of the measured fiber. The tuning information is then used to resample the raw signal, and the nonlinearity correction can be achieved. The spatial resolution test and the distributed strain measurement test were both performed based on this nonlinearity correction method. The results validated the feasibility of the proposed method. This method reduces the hardware and data burden for the system and has potential value for system integration and miniaturization. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

20 pages, 9764 KiB

Open AccessArticle

Dynamic Deformation Reconstruction of Variable Section WING with Fiber Bragg Grating Sensors

by Zhen Fu, Yong Zhao, Hong Bao and Feifei Zhao

Sensors 2019, 19(15), 3350; https://0-doi-org.brum.beds.ac.uk/10.3390/s19153350 - 30 Jul 2019

Cited by 13 | Viewed by 2613

Abstract

In order to monitor the variable-section wing deformation in real-time, this paper proposes a dynamic reconstruction algorithm based on the inverse finite element method and fuzzy network to sense the deformation of the variable-section beam structure. Firstly, based on Timoshenko beam theory and inverse finite element framework, a deformation reconstruction model of variable-section beam element was established. Then, considering the installation error of the fiber Bragg grating (FBG) sensor and the dynamic un-modeled error caused by the difference between the static model and dynamic model, the real-time measured strain was corrected using a solidified fuzzy network. The parameters of the fuzzy network were learned using support vector machines to enhance the generalization ability of the fuzzy network. The loading deformation experiment shows that the deformation of the variable section wing can be reconstructed with the proposed algorithm in high precision. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

19 pages, 45843 KiB

Open AccessArticle

Metal Forming Tool Monitoring Based on a 3D Measuring Endoscope Using CAD Assisted Registration

by Lennart Hinz, Markus Kästner and Eduard Reithmeier

Sensors 2019, 19(9), 2084; https://0-doi-org.brum.beds.ac.uk/10.3390/s19092084 - 05 May 2019

Cited by 11 | Viewed by 3341

Abstract

In order to provide timely, reliable, and comprehensive data for the maintenance of highly stressed geometries in sheet-bulk metal forming tools, this article features a possible setup by combining a 3D measuring endoscope with a two-stage kinematic. The measurement principle is based on the projection of structured light, allowing time-effective measurements of larger areas. To obtain data of proper quality, several hundred measurements are performed which then have to be registered and finally merged into one single point cloud. Factors such as heavy, unwieldy specimens affecting precise alignment. The rotational axes are therefore possibly misaligned and the kinematics and the hand-eye transformation remain uncalibrated. By the use of computer-aided design (CAD) data, registration can be improved, allowing a detailed examination of local features like gear geometries while reducing the sensitivity to detect shape deviations. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

11 pages, 5784 KiB

Open AccessArticle

A High Sensitivity Temperature Sensing Probe Based on Microfiber Fabry-Perot Interference

by Zhoubing Li, Yue Zhang, Chunqiao Ren, Zhengqi Sui and Jin Li

Sensors 2019, 19(8), 1819; https://0-doi-org.brum.beds.ac.uk/10.3390/s19081819 - 16 Apr 2019

Cited by 36 | Viewed by 4226

Abstract

In this paper, a miniature Fabry-Perot temperature probe was designed by using polydimethylsiloxane (PDMS) to encapsulate a microfiber in one cut of hollow core fiber (HCF). The microfiber tip and a common single mode fiber (SMF) end were used as the two reflectors of the Fabry-Perot interferometer. The temperature sensing performance was experimentally demonstrated with a sensitivity of 11.86 nm/°C and an excellent linear fitting in the range of 43–50 °C. This high sensitivity depends on the large thermal-expansion coefficient of PDMS. This temperature sensor can operate no higher than 200 °C limiting by the physicochemical properties of PDMS. The low cost, fast fabrication process, compact structure and outstanding resolution of less than 10⁻⁴ °C enable it being as a promising candidate for exploring the temperature monitor or controller with ultra-high sensitivity and precision. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

27 pages, 10269 KiB

Open AccessReview

Hybrid Plasmonic Fiber-Optic Sensors

by Miao Qi, Nancy Meng Ying Zhang, Kaiwei Li, Swee Chuan Tjin and Lei Wei

Sensors 2020, 20(11), 3266; https://0-doi-org.brum.beds.ac.uk/10.3390/s20113266 - 08 Jun 2020

Cited by 27 | Viewed by 5159

Abstract

With the increasing demand of achieving comprehensive perception in every aspect of life, optical fibers have shown great potential in various applications due to their highly-sensitive, highly-integrated, flexible and real-time sensing capabilities. Among various sensing mechanisms, plasmonics based fiber-optic sensors provide remarkable sensitivity benefiting from their outstanding plasmon–matter interaction. Therefore, surface plasmon resonance (SPR) and localized SPR (LSPR)-based hybrid fiber-optic sensors have captured intensive research attention. Conventionally, SPR- or LSPR-based hybrid fiber-optic sensors rely on the resonant electron oscillations of thin metallic films or metallic nanoparticles functionalized on fiber surfaces. Coupled with the new advances in functional nanomaterials as well as fiber structure design and fabrication in recent years, new solutions continue to emerge to further improve the fiber-optic plasmonic sensors’ performances in terms of sensitivity, specificity and biocompatibility. For instance, 2D materials like graphene can enhance the surface plasmon intensity at the metallic film surface due to the plasmon–matter interaction. Two-dimensional (2D) morphology of transition metal oxides can be doped with abundant free electrons to facilitate intrinsic plasmonics in visible or near-infrared frequencies, realizing exceptional field confinement and high sensitivity detection of analyte molecules. Gold nanoparticles capped with macrocyclic supramolecules show excellent selectivity to target biomolecules and ultralow limits of detection. Moreover, specially designed microstructured optical fibers are able to achieve high birefringence that can suppress the output inaccuracy induced by polarization crosstalk and meanwhile deliver promising sensitivity. This review aims to reveal and explore the frontiers of such hybrid plasmonic fiber-optic platforms in various sensing applications. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

43 pages, 4159 KiB

Open AccessReview

Carbon Allotrope-Based Optical Fibers for Environmental and Biological Sensing: A Review

by Stephanie Hui Kit Yap, Kok Ken Chan, Swee Chuan Tjin and Ken-Tye Yong

Sensors 2020, 20(7), 2046; https://0-doi-org.brum.beds.ac.uk/10.3390/s20072046 - 05 Apr 2020

Cited by 26 | Viewed by 4273

Abstract

Recently, carbon allotropes have received tremendous research interest and paved a new avenue for optical fiber sensing technology. Carbon allotropes exhibit unique sensing properties such as large surface to volume ratios, biocompatibility, and they can serve as molecule enrichers. Meanwhile, optical fibers possess a high degree of surface modification versatility that enables the incorporation of carbon allotropes as the functional coating for a wide range of detection tasks. Moreover, the combination of carbon allotropes and optical fibers also yields high sensitivity and specificity to monitor target molecules in the vicinity of the nanocoating surface. In this review, the development of carbon allotropes-based optical fiber sensors is studied. The first section provides an overview of four different types of carbon allotropes, including carbon nanotubes, carbon dots, graphene, and nanodiamonds. The second section discusses the synthesis approaches used to prepare these carbon allotropes, followed by some deposition techniques to functionalize the surface of the optical fiber, and the associated sensing mechanisms. Numerous applications that have benefitted from carbon allotrope-based optical fiber sensors such as temperature, strain, volatile organic compounds and biosensing applications are reviewed and summarized. Finally, a concluding section highlighting the technological deficiencies, challenges, and suggestions to overcome them is presented. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Graphical abstract

15 pages, 4872 KiB

Open AccessReview

Relative Humidity Sensors Based on Microfiber Knot Resonators—A Review

by Young-Geun Han

Sensors 2019, 19(23), 5196; https://0-doi-org.brum.beds.ac.uk/10.3390/s19235196 - 27 Nov 2019

Cited by 16 | Viewed by 3350

Abstract

Recent research and development progress of relative humidity sensors using microfiber knot resonators (MKRs) are reviewed by considering the physical parameters of the MKR and coating materials sensitive to improve the relative humidity sensitivity. The fabrication method of the MKR based on silica or polymer is briefly described. The many advantages of the MKR such as strong evanescent field, a high Q-factor, compact size, and high sensitivity can provide a great diversity of sensing applications. The relative humidity sensitivity of the MKR is enhanced by concerning the physical parameters of the MKR, including the waist or knot diameter, sensitive materials, and Vernier effect. Many techniques for depositing the sensitive materials on the MKR surface are discussed. The adsorption effects of water vapor molecules on variations in the resonant wavelength and the transmission output of the MKR are described regarding the materials sensitive to relative humidity. The sensing performance of the MKR-based relative humidity sensors is discussed, including sensitivity, resolution, and response time. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

15 pages, 3403 KiB

Open AccessReview

Dual-Polarized Fiber Laser Sensor for Photoacoustic Microscopy

by Xiangwei Lin, Yizhi Liang, Long Jin and Lidai Wang

Sensors 2019, 19(21), 4632; https://0-doi-org.brum.beds.ac.uk/10.3390/s19214632 - 24 Oct 2019

Cited by 8 | Viewed by 4070

Abstract

Optical resolution photoacoustic microscopy (OR-PAM) provides high-resolution, label-free and non-invasive functional imaging for broad biomedical applications. Dual-polarized fiber laser sensors have high sensitivity, low noise, a miniature size, and excellent stability; thus, they have been used in acoustic detection in OR-PAM. Here, we review recent progress in fiber-laser-based ultrasound sensors for photoacoustic microscopy, especially the dual-polarized fiber laser sensor with high sensitivity. The principle, characterization and sensitivity optimization of this type of sensor are presented. In vivo experiments demonstrate its excellent performance in the detection of photoacoustic (PA) signals in OR-PAM. This review summarizes representative applications of fiber laser sensors in OR-PAM and discusses their further improvements. Full article

(This article belongs to the Special Issue Fiber Optic Sensors and Applications)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Fiber Optic Sensors and Applications

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (14 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI