A Review of Coating Materials Used to Improve the Performance of Optical Fiber Sensors

Li, Changxu; Yang, Wenlong; Wang, Min; Yu, Xiaoyang; Fan, Jianying; Xiong, Ya; Yang, Yuqiang; Li, Linjun

doi:10.3390/s20154215

Cited by 67 publications

(30 citation statements)

References 120 publications

(259 reference statements)

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“…The difference between the substrate and coating materials is crucial due to the individual phases (coating and substrate), which leads to differential thermal contraction and expansion stresses during cooling and heating [61]. The expansion coefficient is significant in silica-based coatings [62], adhesives [63], and coatings for optical fiber sensors [64]. Here, the highest thermal expansion coefficient was observed for the substrate itself and the lowest for the (CF)1 sample.…”

Section: Discussionmentioning

confidence: 99%

Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil

et al. 2021

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The reported work was focused on sol–gel-derived organically modified and fluorinated silica coatings deposited on elastic polymeric foil. The structure and topography of the coatings were tested by infrared spectroscopy and microscopic studies. The functional properties were determined using thermal analysis, surface analysis, and oxygen permeability tests. The barrier feature of the investigated materials against oxygen was correlated with the properties of the coatings. The hybrid (organic–inorganic) structure of the coatings was proven, demonstrating the presence of a silica network modified with alkyl and fluoroalkyl groups since precursors with the isooctyl group or different lengths of the fluoroalkyl chains were used for the syntheses. The coatings were free of defects and had a smooth surface except for the sample containing the longest fluoroalkyl chain (perfluorododecyl group), which showed a wrinkle-like surface. The hydrophobic character of the coatings increased, whereas the oxygen permeation coefficient values decreased (reaching a fourfold lower coefficient in comparison to the bare substrate) with a higher content of the fluorinated carbon atoms in the structure. The results were enriched by the information from the thermomechanical analysis as well as nanoindentation and scratch tests giving values of the glass transition temperature, thermal expansion coefficient, coatings adhesion, and hardness of the investigated systems.

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Section: Discussionmentioning

confidence: 99%

Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil

et al. 2021

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“…The schematic diagram of In order to generate the Vernier effect, we need to design the reference cavity. Therefore, the parameters (W span = 80 nm, N = 5 (1 • C), S sensing = 2.056 nm/ • C) can be substituted into Equation (11) to calculate the ratio D as 1.103 and 0.897, respectively. The comparison shows that the D is close to the inequality (D ≥ 1.1 and D ≤ 0.9), which can be solved by Equation (9).…”

Section: Experiments and Discussionmentioning

confidence: 99%

“…The structure of the fiber optic FPI sensor can be grouped into two categories: (i) an intrinsic Fabry-Perot interferometer (IFPI), where the light is reflected by the reflector inside the fiber, a typical example is how the IFPI can be formed by a pair of Bragg gratings separated by a small gap [9], and (ii) an extrinsic Fabry-Perot interferometer (EFPI), where the light exits the fiber and propagates inside the external cavity. Such an external cavity can be made of polymer or an air cavity encapsulated by a diaphragm [10,11]. The development of science and technology puts forward higher requirements for the performance of sensors, such as the need for a high resolution for biomedical applications [12].…”

Section: Introductionmentioning

confidence: 99%

Study of the Vernier Effect Based on the Fabry–Perot Interferometer: Methodology and Application

et al. 2021

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The optical Vernier effect is a powerful tool for improving the sensitivity of an optical sensor, which relies on the use of two sensor units with slightly detuned frequencies. However, an improper amount of detuning can easily cause the Vernier effect to be unusable. In this work, the effective generation range of the Vernier effect and the corresponding interferometer configuration are suggested and experimentally demonstrated through a tunable cascaded Fabry–Perot interferometer structure. We further demonstrate a practical method to increase the magnification factor of the Vernier effect based on the device bandwidth. Only the optical path length of an interferometer probe and the sensitivity of the measurement parameters are needed to design this practical interferometer based on the Vernier effect. Our results provide potential insights for the sensing applications of the Vernier effect.

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“…This coating facilitates the bending of the optical fiber and protects it against corrosion. It is generally made of a polymer such as polydimethylsiloxane, polyimide, or acrylate [ 97 ], or a polymer-based composite [ 94 ]. It was proven by modelling that the longer the bonded length is and the stiffer the coatings are, the more strain is transferred to the optical fiber [ 96 ].…”

Section: Structure Health Monitoringmentioning

confidence: 99%

Fused Filament Fabrication of Polymers and Continuous Fiber-Reinforced Polymer Composites: Advances in Structure Optimization and Health Monitoring

et al. 2021

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3D printed neat thermoplastic polymers (TPs) and continuous fiber-reinforced thermoplastic composites (CFRTPCs) by fused filament fabrication (FFF) are becoming attractive materials for numerous applications. However, the structure of these materials exhibits interfaces at different scales, engendering non-optimal mechanical properties. The first part of the review presents a description of these interfaces and highlights the different strategies to improve interfacial bonding. The actual knowledge on the structural aspects of the thermoplastic matrix is also summarized in this contribution with a focus on crystallization and orientation. The research to be tackled to further improve the structural properties of the 3D printed materials is identified. The second part of the review provides an overview of structural health monitoring technologies relying on the use of fiber Bragg grating sensors, strain gauge sensors and self-sensing. After a brief discussion on these three technologies, the needed research to further stimulate the development of FFF is identified. Finally, in the third part of this contribution the technology landscape of FFF processes for CFRTPCs is provided, including the future trends.

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A Review of Coating Materials Used to Improve the Performance of Optical Fiber Sensors

Cited by 67 publications

References 120 publications

Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil

Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil

Study of the Vernier Effect Based on the Fabry–Perot Interferometer: Methodology and Application

Fused Filament Fabrication of Polymers and Continuous Fiber-Reinforced Polymer Composites: Advances in Structure Optimization and Health Monitoring

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