Nowadays, smart composite materials embed miniaturized sensors for structural health monitoring (SHM) in order to mitigate the risk of failure due to an overload or to unwanted inhomogeneity resulting from the fabrication process. Optical fiber sensors, and more particularly fiber Bragg grating (FBG) sensors, outperform traditional sensor technologies, as they are lightweight, small in size and offer convenient multiplexing capabilities with remote operation. They have thus been extensively associated to composite materials to study their behavior for further SHM purposes. This paper reviews the main challenges arising from the use of FBGs in composite materials. The focus will be made on issues related to temperature-strain discrimination, demodulation of the amplitude spectrum during and after the curing process as well as connection between the embedded optical fibers and the surroundings. The main strategies developed in each of these three topics will be summarized and compared, demonstrating the large progress that has been made in this field in the past few years.

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Fiber Bragg grating sensors toward structural health monitoring in composite materials: challenges and solutions.

Internet of Things (IoT) has recently received a great attention due to its potential and capacity to be integrated into any complex system. As a result of rapid development of sensing technologies such as radio-frequency identification, sensors and the convergence of information technologies such as wireless communication and Internet, IoT is emerging as an important technology for monitoring systems. This paper reviews and introduces a framework for structural health monitoring (SHM) using IoT technologies on intelligent and reliable monitoring. Specifically, technologies involved in IoT and SHM system implementation as well as data routing strategy in IoT environment are presented. As the amount of data generated by sensing devices are voluminous and faster than ever, big data solutions are introduced to deal with the complex and large amount of data collected from sensors installed on structures.

Structural Health Monitoring Framework Based on Internet of Things: A Survey

Fibre Bragg grating (FBG) strain sensors are not only a very well-established research field, but they are also acquiring a bigger market share due to their sensitivity and low costs In this paper we review FBG strain sensors with high focus on the underlying physical principles, the interrogation, and the read-out techniques Particular emphasis is given to recent advances in highly-performing, single head FBG, a category FBG strain sensors belong to Different sensing schemes are described, including FBG strain sensors based on mode splitting Their operation principle and performance are reported and compared with the conventional architectures In conclusion, some advanced applications and key sectors the global fibre-optic strain sensors market are envisaged, as well as the main market players acting in this field

Fibre Bragg Grating Based Strain Sensors: Review of Technology and Applications.

DOI: 10.1002/adom.201801433 Scientific American selects plasmonic sensing as the top 10 emerging technologies of 2018.[15] Almost every single new plasmonic or photonic structure would be explored to test its sensing ability.[16–29] These works tend to report the sensing performance of their own structure. Some declare that their sensitivity breaks the world record. However, there is still a missing literature on what the world record really is, the gap between the experiments and the theoretical limit, as well as the differences between metal-based plasmonic sensors and dielectric-based photonic sensors. To push plasmonic and photonic sensors into industrial applications, an optical sensing technology map is absolutely necessary. This review aims to cover a wide range of most representative plasmonic and photonic sensors, and place them into a single map. The sensor performances of different structures will be distinctly illustrated. Future researchers could plot the sensing ability of their new sensors into this technology map and gauge their performances in this field. In this review, we focus on optical refractive index (RI) sensors with no fluorescent labeling required. We will utilize two parameters to characterize and compare the performance of optical RI sensors: sensitivity to RI change (denoted by symbol SRI) and figure of merit (in short, FoM). For simplicity, we restrict our discussions to bulk RI change, where the change in RI occurs within the whole sample. There is another case where the RI variation occurs only within a very small volume close to the sensor surface. This surface RI sensitivity is proportional to the bulk RI sensitivity, the ratio of the thickness of the layer within which the surface RI variation occurs, and the penetration depth of the optical mode.[6] The bulk RI sensitivity defines the ratio of the change in sensor output (e.g., resonance angle, intensity, or resonant wavelength) to the bulk RI variations. Here, we limit our discussions to the spectral interrogations and the bulk RI sensitivity SRI is given by[3,5–7,30]

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements.

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Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

Automated fibre placement based composite structures: Review on the defects, impacts and inspections techniques

Preface Editors Contributors Introduction to Optical Fiber Sensors Ginu Rajan Optical Fiber Sensing Solutions: From Macro- to Micro-/Nanoscale Yuliya Semenova and Gerald Farrell Interferometric Fiber-Optic Sensors Sara Tofighi, Abolfazl Bahrampour, Nafiseh Pishbin, and Ali Reza Bahrampour Polymer Optical Fiber Sensors Kara Peters Surface Plasmon Resonance Fiber-Optic Sensors Kent B. Pfeifer and Steven M. Thornberg Photonic-Crystal Fibers for Sensing Applications Ana M.R. Pinto Liquid Crystal Optical Fibers for Sensing Applications Sunish Mathews and Yuliya Semenova Optical Microfiber Physical Sensors George Y. Chen and Gilberto Brambilla Fiber Bragg Grating Sensors and Interrogation Systems Dipankar Sengupta Polymer Fiber Bragg Grating Sensors and Their Applications David J. Webb Acousto-Optic Effect and Its Application in Optical Fibers Alexandre de Almeida Prado Pohl Distributed Fiber-Optic Sensors and Their Applications Balaji Srinivasan and Deepa Venkitesh Fiber Laser-Based Sensing Technologies Asrul Izam Azmi, Muhammad Yusof Mohd Noor, Haifeng Qi, Kun Liu, and Gang-Ding Peng Active Core Optical Fiber Chemical Sensors and Applications Shiquan Tao Optical Fiber Humidity Sensors Muhammad Yusof Mohd Noor, Gang-Ding Peng, and Ginu Rajan Medical Applications of Fiber-Optic Sensors Vandana Mishra Optical Fiber Sensors for Smart Composite Materials and Structures Manjusha Ramakrishnan, Yuliya Semenova, Gerald Farrell, and Ginu Rajan Future Perspectives for Fiber-Optic Sensing Brian Culshaw Index

Optical fiber sensors : advanced techniques and applications

Interfacial bonding between fibre and matrix is most critical to obtain enhanced mechanical properties of the resulting composites. Here we present a new surface tailoring method of selective wet etching and organosilicon monomers (3-(Trimethoxysilyl) propyl methacrylate, TMSPMA) deposition process on the short S-Glass fibre as a reinforcing material, resulting in increased mechanical retention and strong chemical bonding between glass fibres and polymer resin (a mixture of triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) monomers). The effect of surface modification on fibre matrix interfacial strength was investigated through microdroplet tests. An S-Glass fibre treated with piranha solution (a mixture of H2O2 and H2SO4) for 24 hours followed by TMSPMA surface silanization shows highest increase up to 39.6% in interfacial shear strength (IFSS), and critical fibre length could be reduced from 916.0 µm to 432.5 µm. We find the optimal surface treatment condition in that the flexural strength of dental composites reinforced by the S-Glass fibres enhanced up to 22.3% compared to the composites without fibre surface treatments. The significant elevation in strength is attributed to changes in the surface roughness of glass fibres at atomic scale, specifically by providing the multiplied spots of the chemical bridge and nano-mechanical interlocking. The findings offer a new strategy for advanced tailoring of short S-Glass fibres to maximise the mechanical properties of biomedical and dental composites.

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Selective Atomic-Level Etching on Short S-Glass Fibres to Control Interfacial Properties for Restorative Dental Composites

The measurement of an unknown wavelength is a common operation for many optical systems. Examples include wavelength monitoring in multichannel dense wavelength division multiplexing (DWDM) optical communication systems and optical sensing systems based on fiber Bragg gratings (FBGs) or Fabry‐Perot (FP) filters. DWDM requires the accurate setting and maintaining of the transmitter’s wavelength or monitoring of the tunable laser’s wavelength. 1,2 An FBG- or FP-filter-based optical

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Ginu Rajan

Papers

Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

Automated fibre placement based composite structures: Review on the defects, impacts and inspections techniques

Optical fiber sensors : advanced techniques and applications

Selective Atomic-Level Etching on Short S-Glass Fibres to Control Interfacial Properties for Restorative Dental Composites

Low-cost wavelength measurement based on a macrobending single-mode fiber