Fluorescent Fibers Research Articles

A ratiometric fluorescent fiber sensor based on integrated silica and tellurite glass for real-time human thermal monitoring

In this paper, we propose and demonstrate a portable fiber sensor with integrated tellurite and silica for dynamic human thermal monitoring, where Er3+/Yb3+ co-doped tellurite glass is employed to generate upconversion fluorescence emission related to thermally coupled energy levels via near-infrared excitation for ratiometric thermometry. The molten tellurite glass is extracted into a silica tube using the negative pressure approach, allowing for intimate adhesion between different glass materials with considerable softening temperature differences. With a fast instantaneous response of 0.4–0.6 s and an absolute error of −0.45–0.36 K, the sensor can accurately and timely capture small temperature fluctuations. The sensor is placed in the mouth or attached to the hand skin to measure the body temperature continually. It is also positioned in the mouth exhalation and nose breathing environments to monitor thermal activities in real-time, offering a new, highly reliable method for human health monitoring.

Water-stable, biocompatible, and highly luminescent perovskite nanocrystals-embedded fiber-based paper for anti-counterfeiting applications

In this study, we present a promising and facile approach toward the fabrication of non-toxic, water-stable, and eco-friendly luminescent fiber paper composed of polycaprolactone (PCL) polymer and CsPbBr3@SiO2 core–shell perovskite nanocrystals. PCL-perovskite fiber paper was fabricated using a conventional electrospinning process. Transmission electron microscopy (TEM) clearly revealed incorporation of CsPbBr3@SiO2 nanocrystals in the fibers, while scanning electron microscopy (SEM) demonstrated that incorporation of CsPbBr3@SiO2 nanocrystals did not affect the surface and diameter of the PCL-perovskite fibers. In addition, thermogravimetric analysis (TGA) and contact angle measurements have demonstrated that the PCL-perovskite fibers exhibit excellent thermal and water stability. The fabricated PCL-perovskite fiber paper exhibited a bright green emission centered at 520 nm upon excitation by ultra-violet (UV) light (374 nm). We have demonstrated that fluorescent PCL-perovskite fiber paper is a promising candidate for anti-counterfeiting applications because various patterns can be printed on the paper, which only become visible after exposure to UV light at 365 nm. Cell proliferation tests revealed that the PCL-perovskite fibers are cytocompatibility. Consequently, they may be suitable for biocompatible anti-counterfeiting. The present study reveals that PCL-perovskite fibers may pave way toward next generation biomedical probe and anti-counterfeiting applications.Graphical

Preparation and characterization of electrospun fluorescent fiber mats as temperature sensors using various polymers

In this study six electrospun fluorescent fiber mats were fabricated using a temperature-sensitive fluorescent dye, a ruthenium complex (tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride, (Ru(dpp)3)), each with one of six different polymers of polyvinyl alcohol (PVA), polyurethane-based hydrogel HydroMed D4 (D4), polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA), poly(styrene-co-acrylonitrile) (PSAN), and poly(acrylonitrile-co-methyl methacrylate) (PANMM). The electrospun fluorescent fiber mats were characterized as fluorescence temperature sensors in aqueous solution and gaseous environment. The electrospun fluorescent fiber mat fabricated from PAN showed good stability over 100 days, short response time (i.e. 4-5 min), and good reversibility in aqueous solution from 5 to 60 °C, whereas the electrospun fiber mat from PMMA showed relatively high sensitivity and good selectivity in air. These two electrospun fluorescent fiber mats were tested as non-invasive sensors for measuring temperature in biological and environmental processes.

An Innovative Fluorescent Fiber Sensor Based on Ce/Tb Co-Doped Silica Fiber for Partial Discharge Detection

A novel fluorescent fiber sensor based on cerium (Ce) and terbium (Tb) co-doped silica fiber (CTDSF) for partial discharge (PD) detection is proposed. The luminescence mechanism and PD detection principle of CTDSF are theoretically investigated. The CTDSF is fabricated using the rod-in-tube technique combined with the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> laser-heated drawing method. The intense emission peak of Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions located at 542 nm ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> - <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> transition) is excited at 302 nm, which indicates the energy transfer between Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions. Moreover, the excitation peak region near 302 nm is well aligned with the PD light emission spectrum. Subsequently, the PD time domain signals of the needle-plate defect are experimentally measured by utilizing the CTDSF sensor, high-frequency current transformer, and plastic scintillation fiber (PSF). And the experimental results demonstrate that the CTDSF sensor can detect PD signals and has an excellent PD detection linear response with a sensitivity of 0.22 ns∙V/pC. Furthermore, the sensitivity of the CTDSF sensor is approximately 2.4 times dramatically higher than that of the PSF sensor. The CTDSF sensor integrated with the all-fiber system is predicted to have a wide range of potential applications for online PD detection.

Fiber enhancement and 3D orientation analysis in label-free two-photon fluorescence microscopy

Fluorescence microscopy can be exploited for evaluating the brain’s fiber architecture with unsurpassed spatial resolution in combination with different tissue preparation and staining protocols. Differently from state-of-the-art polarimetry-based neuroimaging modalities, the quantification of fiber tract orientations from fluorescence microscopy volume images entails the application of specific image processing techniques, such as Fourier or structure tensor analysis. These, however, may lead to unreliable outcomes as they do not isolate myelinated fibers from the surrounding tissue. In this work, we describe a novel image processing pipeline that enables the computation of accurate 3D fiber orientation maps from both grey and white matter regions, exploiting the selective multiscale enhancement of tubular structures of varying diameters provided by a 3D implementation of the Frangi filter. The developed software tool can efficiently generate orientation distribution function maps at arbitrary spatial scales which may support the histological validation of modern diffusion-weighted magnetic resonance imaging tractography. Despite being tested here on two-photon scanning fluorescence microscopy images, acquired from tissue samples treated with a label-free technique enhancing the autofluorescence of myelinated fibers, the presented pipeline was developed to be employed on all types of 3D fluorescence images and fiber staining.

Evaluation of the sailent features in Indian currency notes

Security features are topographies invisible to the naked eye, such as micro-printing or features visible in ultraviolet, transmitted, and oblique light. The present paper focuses on the examination of Indian currency notes such as 2000, 500, 200, 100, 50, 20, and10 in different light sources and with the help of a compound microscope. This kind of examination is very useful when it comes to distinguishing counterfeit currency from genuine one. Crime is increasing day by day, and so is the making of false currency – this study discusses the numerous security or hidden features which are invisible to the naked eye, and therefore may very well be missed by the potential perpetrator. It is the responsibility of the government along with the issuing authority to incorporate these structures into all travel and security documents, including passports, voter-id cards, and many others. These features are implemented either during the manufacturing of the paper itself (e.g., fluorescent fibres) or at the time of printing (e.g., microprinting, watermarks, and other fluorescent features).

Molybdenum Disulphide Coated Fluorescent Fiber for Detection of Corona Discharges in Transformer Oil

Early detection of corona discharge plays a critical role in avoiding catastrophic failure of transformer insulation. In this study, we explore the use of two-dimensional material coated fluorescent fiber for early detection of corona discharge. Specifically, Molybdenum disulphide (MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) material is dip coated over a commercial grade fluorescent since the bandgap of the coated MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> material corresponds to the visible and ultraviolet (UV) spectral regions. Corona inception voltage detection adopting MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> coated fluorescent fiber exhibits detection efficiency with the percentage difference of 32% in comparison to the UHF technique. Also, fiber coating enhances the energy content of the discharge signal by the difference of 150% with respect to uncoated fluorescent fiber. The phase resolved partial discharge studies reveal that the discharge is observed at the peak of the applied AC voltage.

Development of an Active Optical Lens for Arc Flashing Detection.

This paper contains the design of active optical lenses used for the detection of arc flashing emissions. The phenomenon of an arc flashing emission and its characteristics were contemplated. Methods of preventing these emissions in electric power systems were discussed as well. The article also includes a comparison of commercially available detectors. An analysis of the material properties of fluorescent optical fiber UV-VIS-detecting sensors constitutes a major part of the paper. The main purpose of the work was to make an active lens using photoluminescent materials, which can convert ultraviolet radiation into visible light. As part of the work, active lenses with materials such as Poly(methyl 2-methylpropenoate) (PMMA) and phosphate glass doped with lanthanides, such as terbium (Tb3+) and europium (Eu3+) ions, were analyzed. These lenses were used to make optical sensors, which were supported by commercially available sensors in their construction.

Exemplarily view on selected fluorescence textile products

Fluorescent materials emit light of higher wavelength, in case of illumination with light exhibiting lower wavelength. In many commercial applications, fluorescent materials transfer non-visible ultraviolet (UV) light into visible light. By this an additional color effect and higher visibility is reached. One typical field for application of fluorescence dyes is the textile area. Here, fluorescent textile products are manifold used and offered, e.g. for brightening effects, light effects and UV protection. With this background, the aim of the current study is the investigation of typical commercially available textile products with fluorescent properties. For this, four different polyester fiber-based materials of different coloration and purpose are selected for investigation. Investigations are performed by illumination under different illumination arrangements with UV light and visible light. CIE-Lab measurements are done. Further, scanning electronic microscopy (SEM) and Fourier Transform infrared (FT-IR) spectroscopy are used. Light emission and excitation of the samples is recorded by fluorescence spectroscopy. 2D fluorescence spectroscopy is performed. The chemical composition of the investigated textile samples is determined by using electron dispersive spectroscopy (EDS). For all investigated commercial textile products, the light emission during illumination with UV light is extraordinary strong. The color appearance can be enhanced strongly by this fluorescence effect. Beside the absorption of UV light by the present fluorescence dyes, also the presence of titanium dioxide supports an UV protective property of the textile samples. Finally, it can be concluded that fluorescent fiber materials are well established products for advanced and functional textiles. These materials can be even found in cost effective and everyday consumer products.

Study of using different colors of fluorescent fibers as optical antennas in white LED based-visible light communications.

A fluorescent fiber can be used as an optical antenna in visible light communication (VLC) for simultaneous optical filtering and light concentration and therefore to build a compact receiver. Since its light concentration principle is based on fluorescence, it can exceed the étendue limit and achieve both a high concentration gain and a wide field-of-view (FOV). In addition, because the photoluminescence (PL) lifetime of the fluorophore is typically only several nanoseconds, it can support high-speed data transmissions. When a fluorescent fiber antenna is used in a white light-emitting diode (LED)-based VLC system, the transmission performance highly depends on how the absorption and emission spectra of the fluorophore are associated with both the spectrum of the LED and the responsivity of the silicon photodetector. In this paper, we analyze the performance of several different commercially available fluorescent fibers. We show that, when the data rate is low or the transmission distance is long, since the light emitted from a red fluorescent fiber is associated with high silicon responsivities, it can result in high signal-to-noise ratios (SNRs) at the receiver output and therefore lead to low transmission error rates. In contrast, when the data rate is high or the transmission distance is relatively short, the bandwidth dominates the overall performance and consequently the green fluorescent fiber has better performance since it only absorbs the light emitted from the blue LED rather than the light emitted from the yellow phosphor.

Understanding the Electro-Rheological Aspects of Nano Silica Based Ester Fluid With Surfactants and Deep Learning-Based Prediction of ECT

The present study deals with understanding the impact of different surfactants with nano-silica based ester fluid on its electrical and rheological properties. The stability of nanofluid is of prime concerns, which is achieved by the inclusion of ionic and non-ionic surfactants viz. cetyl trimethyl ammonium bromide (CTAB), oleic acid and Span-80. It is observed that CTAB as surfactant has shown discharge resistance property along with high breakdown strength enhancement of up to 39.5% with ester nanofluid. It is observed that fluorescent fiber technique is more sensitive to identify the inception of corona discharge as compared to Ultra high frequency sensor. The permittivity and tan <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\delta $ </tex-math></inline-formula> of the fluid have shown marginal increase with the addition of surfactants, irrespective of temperature of the fluid. Rheological properties of the liquid showed only Newtonian flow behaviour even upon inclusion of the surfactant. The viscosity of the base fluid and the nanofluids exhibits similar decay rate at higher temperatures. Electrostatic charging tendency (ECT) derives the correlation between rotation speed and the static current measured adopting spinning disc technique. In addition, the performance of Long Short-Term Memory (LSTM) model is efficient compared to Artificial Neural Network (ANN) model adopted in predicting the charging tendency incorporating electro-rheological parameters at distinct temperatures. The electrical and rheological characteristics suggests the implication of nanofluids with surfactant to enhance the insulation performance for transformer applications.

Ratiometric Fluorescence Optical Fiber Sensing for On-Site Ferric Ions Detection Using Single-Emission Carbon Quantum Dots

A carbon quantum dots (CQDs)-based ratiometric fluorescence fiber sensing method for Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> on-site detection is developed. In the proposed ratiometric sensing system, only one kind of single-emission fluorescent material is used. The method of ratiometric sensing provides correction for environmental interferences and eliminates the fluctuations caused by the light source. In this sensing system, the LED light source is not only used to supply the light for excitation, but also provide the internal standard for ratiometric sensing. The CQDs are synthesized by a simple hydrothermal method and can be immobilized on the fiber easily in seconds without molds. The designed annular fiber tip has the advantages of high-efficiency collection of fluorescence and long service life. It is found that concentration of ferric ions can be detected in the range of 0-40 μM by the sensing system. The limit of detection (LOD) is as low as 0.3 μM, which is close to the LOD obtained by dispersing the carbon quantum dots in the solution. The response time is only 6 seconds. The sensing probe with the rapid response is only 4 mm in length with the maximum diameter of 350 μm, showing great potential on real-time detection in narrow area. The practicability and reliability of the present system is verified by actual samples.

Wet-spinning fluorescent alginate fibres achieved by doping PEI modified CPDs for multiple anti-counterfeiting

Carbonized polymer dots (CPDs) with satisfactory excitation-dependent-emission and biocompatibility had great potential in anti-counterfeiting fibres field. However, it was difficult for CPDs to combined into the fibres due to the unstable interaction between CPDs and spinnable polymer matrix. Polyethyleneimine (PEI) was used to modify CPDs (namely PEI-CPDs) for achieving stable interactions with sodium alginate (SA) by a simple method, which including the physical interaction between the amino groups of PEI-CPDs and carboxyl groups of SA and the chain entanglement between two types of polymer chains. Then alginate fibres based on PEI-CPDs (PEI-CPDs/CaALG fibres) were successfully prepared by wet-spinning for the first time with less loss of PEI-CPDs. The high mechanical strength, excellent thermal stability and good biocompatibility achieved by PEI-CPDs/CaALG fibres. Furthermore, the fibres exhibited the excitation-dependent-emission property. Anti-counterfeiting of the fibres was conducted on both textile and papers, which showed higher security than the existing anti-counterfeiting fibres.

Chitosan grafting coumarin-3-carboxylic acid fluorescent fiber with enhanced strength prepared by in-situ wet-spinning

Chitosan grafting coumarin-3-carboxylic acid (CS-g-CCA) fiber with fluorescent function and enhanced tensile strength was successfully prepared by in-situ wet-spinning. FTIR and NMR results demonstrate that CCA is successfully grafted onto the CS molecule chains. As the grafting rate increases from 4.2 to 15.8 %, the spinning solution viscosity increases from 22 to 54 Pa·s. SEM observations show that the CS and CS-g-CCA fiber surfaces and cross-sections exhibit homogeneity and smoothness. Likewise, as the drawing ratio increases from 1.0 to 1.4, 2D WAXS patterns illustrate the molecular chain oriented significantly along the drawing direction. The CS-g-CCA fiber (the grafting rate of 15.8 %) exhibits a maximum breaking strength of 1.06 cn/dtex, increasing by 20 % more than the CS fiber. Meanwhile, it has a peak fluorescence intensity of around 480 nm. In addition, the continuous preparation process simplifies the technological route and improves the preparation efficiency of CS-g-CCA fiber. As-prepared CS-g-CCA fiber with enhanced tensile strength and elevated fluorescence efficiency lays the foundation for potential application in fluorescent probes, anti-counterfeiting, and biomedicine fields.

Microstructure-based engineering of soft biological materials

Aortic disease (AoD) is a leading cause of mortality in developed countries. Two of the most common forms of AoD are aneurysm (widening) and dissection (tear in inner wall). Aneurysm and dissection often associate with bicuspid aortic valve (BAV) instead of the normal tricuspid aortic valve, and BAV aneurysms of ascending thoracic aorta have the tendency to bulge asymmetrically towards the greater curvature of aorta. Multiphoton microscopy can help us image collagen and elastin fibres, which are considered as main load-bearing constituents of the aortic wall, in order to investigate potential role of fibre microstructure in ascending thoracic aortic aneurysm or dissection. Regional differences in fibre microstructure may be driven by distinct mechanisms of vascular remodelling, and, combined with mechanical tests, could improve our understanding of the biomechanical mechanisms of aortic aneurysm and dissection potential. Should we wish to investigate the effect of microstructure in soft tissue formation and organ development, we would have to consider a rapidly growing process. In that process, the cells are the main load-bearing components, which cooperate to produce tissue-level forces that shape tissue formation. Our understanding of this phenomenon, called mechanotransduction, has advanced significantly over the past years, to the point where it is now clear that nearly every biological process is modulated by how these forces are decoded intracellularly. It is therefore important to create our own fluorescently-labeled matrix that could integrate into the tissue and enable tracking of these forces in-vivo. A new 3D optical nanomechanical biosensor (NMBS) based on fluorescent fibronectin fibres was developed based on integrated photolithography and micro-contact printing technology. NMBS was successfully validated under uniaxial tensile test of biologically relevant materials for microscopic vs. macroscopic mechanical strains. In the future, biomimetic 3D scaffolds could be fabricated by assembly of 2D fibre constructs based on the NMBS technology, in order to analyse the effect of selected set of load-bearing microstructural components on both mechanical and functional response of soft biological materials.

Mechanical artifacts in optical projection tomography: classification and automatic calibration

Optical projection tomography (OPT) is a powerful tool for biomedical studies. It achieves 3D visualization of mesoscopic biological samples with high spatial resolution using conventional tomographic-reconstruction algorithms. However, various artifacts degrade the quality of the reconstructed images due to experimental imperfections in the OPT instruments. While many efforts have been made to characterize and correct for these artifacts, they focus on one specific type of artifacts, whereas a comprehensive catalog of all sorts of mechanical artifacts does not currently exist. In this work, we systematically document many mechanical artifacts. We rely on a 3D description of the imaging system that uses a set of angular and translational parameters. We provide a catalog of artifacts. It lists their cause, resulting effects, and existing correction methods. Then, we introduce an automatic calibration algorithm that is able to recover the unknown system parameters fed into the final 3D iterative reconstruction algorithm for a distortion-free volumetric image. Simulations with beads data and experimental results on a fluorescent textile fiber confirm that our algorithm successfully removes miscalibration artifacts in the reconstruction.

Optical Detection Method for Partial Discharge of Printed Circuit Boards in Electrified Aircraft Under Various Pressures and Voltages

Realization of an electrical aircraft demands a low-weight electric distribution and propulsion system. The use of high voltage and power electronics operated at high switching frequencies is essential to achieve this objective. However, printed circuit boards (PCBs) in electrified aircraft are in a harsh working environment, which can make PCBs more susceptible to generate partial discharges (PDs). The current PD detection technology has poor immunity to the electromagnetic interference and acoustic interference in the operating environment of aircraft. Therefore, this article proposes an optical-based PD detection method for PCBs, which is effectively immune to electromagnetic and acoustic interference. This method uses fluorescent fiber as a PD optical signal sensor and then collects the optical signal by the avalanche photodiode (APD). Experiments have verified that the detection sensitivity, sensing range, and anti-interference performance of this method are well satisfied with the PD detection. In addition, single PD pulse, optical phase resolved PD (PRPD) patterns, and PD inception voltage (PDIV) under different air pressure and voltage conditions are investigated. Finally, the relationship between the optical signal and PD amplitude is found to be proportional, which proves that the severity of the PD on PCBs can be effectively detected and evaluated by this method.

Subiculum fiber degeneration within the fornix white matter tract in 5xFAD mice

AbstractBackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disease that affects all components of the neurovascular unit. The hallmark pathology of AD, amyloid plaques and tau neurofibrillary tangles, aggregate within gray matter areas and spread across neural networks. Although AD pathology is scarce within white matter brain regions, white matter abnormalities have been observed in AD patients using diffusion tensor imaging (DTI; Sachdev et al 2013) and white matter tracts are putative therapeutic targets for deep brain stimulation (Lam et al 2020). Particularly, the fornix is a white matter tract which connects the hippocampus to brain regions of the classic Papez circuit and Default Mode Network (DMN). A recent whole brain analysis using transgenic 5xFAD/Thy1‐GFP mouse (Zhang et al 2020) found evidence of fornix degeneration and dystrophic axon terminals within the mammillary body (a major SUB target) occurring as early as 2 months of age. However, due to the broad expression of GFP under the Thy1 promotor, it is difficult to determine the origin of axon fibers and further characterize if other SUB pathways are also affected.MethodTo investigate white matter changes in AD and further characterize SUB axon degeneration, we performed triple anterograde tract‐tracing of SUB axon fibers and post‐mortem DTI tractography imaging within the same 8‐9 mo. old 5xFAD mice.ResultDTI imaging revealed a significant decrease in fiber density of the fornix white matter tract in 5xFAD mice. Quantification of tracer‐labeled fluorescent fiber density in the 5xFAD mice vs control mice also revealed significant degeneration of SUB fibers within the fornix white matter as well as downstream SUB targets including mammillary body, retrosplenial cortex, and anterior thalamus. Furthermore, SUB axon terminals in 5xFAD mice appeared dystrophic and terminal field topography was disrupted.ConclusionDTI imaging and anatomical tract tracing approaches reveal white matter degeneration in 5xFAD mice and the fornix/SUB fibers are particularly vulnerable in AD. Diminished SUB input to brain regions of the Papez circuit/DMN likely leads to neural network dysfunction. Whether amyloid pathology, neurovascular dysfunction, or inflammatory response in the 5xFAD mouse contributes to white matter degeneration remains to be determined by future studies.

Luminous Self-Assembled Fibers of Azopyridines and Quantum Dots Enabled by Synergy of Halogen Bond and Alkyl Chain Interactions

Herein, a simple approach for the fabrication of luminous self-assembled fibers based on halogen-bonded azopyridine complexes and oleic acid-modified quantum dots (QDs) is reported. The QDs uniformly align on the edge of the self-assembled fibers through the formation of van der Waals force between the alkyl chain of oleic acid on the QD surface and the alkyl chain of the halogen-bonded complexes, 15Br or 15I. Furthermore, the intermolecular interaction mechanism was elucidated by using Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and density functional theory (DFT) calculations. This approach results in retention of the fluorescence properties of the QDs in the fibers. In addition, the bromine-bonded fibers can be assembled into tailored directional fibers upon evaporation of the solvent (tetrahydrofuran) when using capillaries via the capillary force. Interestingly, the mesogenic properties of the halogen-bonded complexes are preserved in the easily prepared halogen-bonded fluorescent fibers; this provides new insight into the design of functional self-assembly materials.

Localization of Partial Discharge Using All-Fiber System Based on Crystal Fluorescent Fiber

Partial discharge (PD) is a common defect to determine the quality of high-voltage power equipment insulation systems. Localization of PD is very important for equipment maintenance and risk assessment. A localization algorithm of received signal strength (RSS) using demodulating PD optical signal is proposed. This is based on the optical effects caused by PD, which influence the optical signal that is transmitted through an optical fiber sensor placed inside the equipment. Compared with plastic fluorescent fiber, SiO2 cladding YAP:Ce crystal core fluorescent fiber (SYCF) with high luminous efficiency, low loss, and strong anti-electromagnetic interference capability is selected as the sensing unit to detect the received optical signal strength of PD, through the all-fiber optic sensing system to achieve the PD location in 3-D space. Based on the optical RSS localization method, the range of localization deviation of PD under 37-kV applied voltage is measured and studied. The average localization deviation and the error are 6.9 cm and 7.4%, respectively. Comparing the optical signal location method based on RSS with other methods of PD localization, the advantages and accuracy of the optical location method proposed in this article are outstanding. Therefore, the all-fiber system with SYCF via optical signal has a wide application prospect in the spatial localization of PD.