Plastic Optical Fiber Research Articles

Superhydrophobic Tipped Antimicrobial Photodynamic Therapy Device for the In Vivo Treatment of Periodontitis Using a Wistar Rat Model.

Limited options exist for treatment of periodontitis; scaling and root planing (SRP) are not sufficient to eradicate P. gingivalis and the resulting inflammatory disease. Chlorhexidine (CHX), used as an adjuvant to SRP, may reduce bacterial loads but leads to pain and staining, while evidence for its efficacy is lacking. Antibiotics are effective but can lead to drug-resistance. The rising concern of antibiotic resistance limits the future use of this treatment approach. This study evaluates the efficacy of a novel superhydrophobic (SH) antimicrobial photodynamic therapy (aPDT) device as an adjuvant to SRP for the treatment of periodontitis induced in a Wistar rat in vivo model relative to CHX. The SH-aPDT device comprises an SH silicone rubber strip coated with verteporfin photosensitizer (PS), sterilized, and secured onto a tapered plastic optical fiber tip connected to a red diode laser. The superhydrophobic polydimethylsiloxane (PDMS) strips were fabricated by using a novel soluble template method that creates a medical-grade elastomer with hierarchical surface roughness without the use of nanoparticles. Superhydrophobicity minimizes direct contact of the PS-coated surface with bacterial biofilms. Upon insertion of the device tip into the pocket and energizing the laser, the device generates singlet oxygen that effectively targets and eliminates bacteria within the periodontal pocket. SH-aPDT treatment using 125 J/cm2 of red light on three consecutive days reduced P. gingivalis significantly more than SRP-CHX controls (p < 0.05). Clinical parameters significantly improved (p < 0.05), and histology and stereometry results demonstrated SH-aPDT to be the most effective treatment for improving healing and reducing inflammation, with an increase in fibroblast cells and extracellular matrix and a reduction in vascularization, inflammatory cells, and COX-2 expression. The SH-aPDT approach resulted in complete disease clearance assessed 30 days after treatment initiation with significant reduction of the periodontal pocket and re-formation of the junctional epithelium at the enamel-cementum junction. PS isolation on a SH strip minimizes the potential for bacteria to develop resistance, where the treatment may be aided by the oxygen supply retained within the SH surface.

U-shaped plastic optical fiber sensor for phosphate detection in water

U-shaped plastic optical fiber sensor for phosphate detection in water

Optimizing Gas Sensing Performance of CuO Nanoparticles via Sol-Gel Synthesis Approach for Efficient Detection of Ammonia Gas

In this study, we present a plastic optical fiber for volatile organic compound (VOC) gas sensing, where a small portion of the cladding was replaced by CuO sensing material. The structural characterization of the CuO was assessed via powder diffraction X-ray analysis (XRD) and morphological analysis done by SEM imaging. For a variety of VOC gas concentrations, such as ammonia, ethanol, and methanol (0-500 parts per million), as well as for various lengths (1.5 cm and 3 cm) of sensing materials coated on the optical fiber, the spectrum properties of the CuO-coated fiber optic gas sensor were investigated. The 3cm coated CuO over the clad modified region of the plastic optical fiber showed highest intensity of fluctuation towards ammonia gas at wavelengths of 682, 753, and 926 nm, indicating that it is more sensitive to the gas and has a faster response and recovery rate at room temperature than the other two gases.

Fiber-Optic Nanosensors for Chemical Detection

Recently, rapid progress has been achieved in the field of nanomaterial preparation and investigation. Many nanomaterials have been employed in optical chemical sensors and biosensors. This review is focused on fiber-optic nanosensors for chemical sensing based on silica and plastic optical fibers. Four types of fiber-optic chemical nanosensors, namely fiber nanotip sensors, fiber nanoarray sensors, fiber-optic surface plasmon resonance sensors, and fiber-optic nanomaterial-based sensors, are discussed in the paper. The preparation, materials, and sensing characteristics of the selected fiber-optic nanosensors are employed to show the performance of such nanosensors for chemical sensing. Examples of fiber-optic nanobiosensors are also included in the paper to document the broad sensing performance of fiber-optic nanosensors. The employment of fiber-nanotips and nanoarrays for surface-enhanced Raman scattering and nanosensors employing both electrical and optical principles and “Lab-on-fiber” sensors are also included in the paper. The paper deals with fiber-optic nanosensors based on quantum dots, nanotubes, nanorods, and nanosheets of graphene materials, MoS2, and MXenes.

A facile optical sensor: Plastic optical fiber voids as a liquid level presence sensor

Optical sensors use light to detect or monitor different phenomena. Plastic optical fibers (POFs) have larger core diameters and are more flexible and easier to handle than glass optical fibers, making them perfect for many sensing applications. This paper introduces a facile POF sensor to monitor the liquid level and the liquid/gas presence in a specific container by introducing a void in the POF's path. Multiple readings were gathered over two days to verify the sensor's consistent performance. The findings demonstrated that, when exposed to air, the sensor exhibited an average reading of 2.15 V, while its average reading increased to 2.56 V when submerged in water. Such a sensing system can be beneficial in dangerous and explosive environments where electrical sensors or signals are risk factors.

Hybrid Organic–Inorganic PMMA Optical Fibers Functionalized with Photochromic Active WO3 Nanoparticles: From Materials Design to Photochromic Fabrics

AbstractHere, the direct incorporation of photochromic WO3 nanoparticles is investigated in a matrix of polymethyl methacrylate (PMMA) by bulk radical polymerization for the fabrication of plastic optical fibers (POFs). All the prepared composites, from preforms to 1D single fibers and 2D fabrics, are thoroughly investigated, leading to insight into their thermal, morphological, and photochromic properties (coloring/bleaching amplitudes and kinetics). It is found that the preforms exhibit partially irreversible photochromic behavior, whereas the single fibers proved to be effectively reversibly photochromic through a degradation of transmission signal upon UV irradiation and a full recovery under dark conditions. The as‐prepared PMMA plastic fibers, both undoped and doped, show good homogeneity without any imperfections or contamination. The WO3 nanoparticles play a dual role as intrinsic and extrinsic absorption centres leading to higher transmission losses. Finally, a hand‐made textile woven with a bundle of doped fibers is presented. The proposed 1D single fibers and 2D fabrics demonstrate their great potential as novel hybrid inorganic–organic materials in the domain of flexible UV‐sensors and photochromic smart textile with improved color stability and lifetime.

Intelligent fiber optic integrated sensing system for human motion monitoring

In recent years, the development of flexible bend sensors and their detection devices has attracted great interest. In this paper, an intelligent wearable plastic optical fiber (POF) integrated sensing system for human motion detection is presented. The system consists of POF bend sensors and a wearable fiber bend detection meter (WFBDM). By capturing the POF array image from the video stream, it realizes a sampling frequency of 91.7 times/s. It also greatly increases the integration of multiple sensors, with an integrated sensing area of only 0.35*0.35 mm2 for a single sensor. POF bending sensors with a diameter of 0.25 mm were tested using this system with a linear range of −40° to 90°, an accuracy of up to 0.4°, and a response time of 26.2 ms. The system has been successfully applied to human joint and muscle motion monitoring, and combined with machine learning to realize the intelligent recognition of human motion state. The sensing system is small in size, large in sensing range, high in sensitivity and good in stability, and has the ability of intelligent recognition and highly integrated multi-channel bend signals sensing.

Modelling and numerical simulation optimization of output spectra of PbSe doped quantum dot fiber light source based on genetic algorithm

Optical fiber amplifiers mainly use rare earth elements as dopants. In the past 20 years, with the research on plastic optical fiber amplifiers doped with different natural elements (such as erbium and thulium), the performance of optical fiber amplifiers has been significantly improved. However, the application potential of natural elements has reached its limit. To improve optical communication, researchers are working on a fiber amplifier with a better flat gain and more intense light. In this paper, the quantum dot fiber amplifier is treated as a three-level structure, and a genetic algorithm is used to optimize the quantum dot fiber amplifier to maximize the total output power. In this study, by solving and analyzing the rate and power propagation equations of the numerical model, the gain spectrum of the amplifier at a wavelength of 1200~1700nm is obtained as a function of fiber length and doping concentration. Draw three-dimensional images based on fiber length, doping concentration, and ASE power axis to find the maximum power at the highest point of the image. Then, combined with the optimization results of the genetic algorithm, the maximum value of the total power is obtained.

Theoretical and experimental investigation of the steady-state power distribution in multimode step-index plastic optical fibers

In this work we have examined theoretically and experimentally the influence of mode coupling on steady-state distribution (SSD) in step-index plastic optical fiber (SI POF). Numerical and analytical solution of the PFE under steady-state conditions are compared to our experimental results. A numerical solution of the power flow equation (PFE) has been obtained by the explicit finite difference method (EFDM). We demonstrated that SSD in the SI POF is achieved at length of 140 m, which is much shorter length compared to the case with silica fibers. The reported results appear to be particularly important since none of the main optical properties of an optical fiber (attenuation, bandwidth) can be accurately determined until the transmitted optical power reaches its SSD, due to strong influence of mode coupling phenomena that occur during the transmission process. These results are important for employment of the SI POFs as a part of communication or sensory systems.

Evaluation of a Scintillating Plastic Optical Fiber Device for Measuring kV-Cone Beam Computed Tomography Dose.

Justification of imaging procedures such as cone beam computed tomography (CBCT) in radiotherapy makes no doubt. However, the CBCT composite dose is rarely reported or optimized, even though the repeated CBCT cumulative dose can be up to 3% of the prescription dose. This study aimed to evaluate the performance and utility of a new plastic scintillating optical fiber dosimeter for CBCT dosimetric quality assurance (QA) applications before a potential application in patient composite CBCT dosimetry. The dosimeter, made of 1 mm diameter plastic fiber, was installed under a linear accelerator treatment table and linked to photodetectors. The fiber impact on the fluence and dose delivered was respectively assessed with an electronic portal imaging device (EPID) and EBT3 Gafchromic® film. The presence of artifacts was visually evaluated on kV images. The dosimeter performances were determined for various acquisition parameters by comparison with ionization chamber values. The maximum impact of the fiber on the fluence measured by the EPID was -1.2% for the 6 MV flattening filter-free beam. However, the fiber did not alter the film dose profile when measured for all the beams tested. The fiber was not visible at energies ≥ 80 kV and was merely visible on the CBCT images. When the rate of images per second or mA was changed, the maximum relative difference between the device and the ionization chamber CTDIs was <5%. Changing collimation led to a -7.2% maximum relative difference with an absolute dose difference that was insignificant (-0.3 mGy). Changing kV was associated with a -8.7% maximum relative difference, as published in the literature. The dosimeter may be a promising device for CBCT recurrent dosimetry quality control or dose optimization. According to these results, further developments are in progress in order to adapt the solution to the measurement of patient composite CBCT doses.

Video Motion Magnification and Subpixel Edge Detection-Based Full-Field Dynamic Displacement Measurement

Noncontact measurement techniques in structural dynamics field have progressed significantly in the past few decades. Vision-based measurement techniques are unique in that they have the ability to achieve full-field measurement and possess the typical advantages associated with noncontact measurement techniques. Recently, vision-based techniques have also been applied to streaming of videos for structural dynamic displacement measurement. The most recent trends in vision-based measurements include target tracing, digital image correlation, and target-less approaches. There are, however, some shortcomings of the vision-based techniques such as susceptibilities to image noise, prevailing light conditions, and limit in measurement resolution. To reduce these shortcomings, a method known as video motion magnification (MM) can be used to amplify small structural motions. Using the phase-based motion magnification (PBMM) and subpixel edge detection methods, the full-field dynamic displacements of the structure can be obtained. The deep convolutional long short-term memory (ConvLSTM) network is applied to aid in the selection of the frequency band for magnification in the PBMM algorithm. To achieve higher measurement accuracy, the displacement results with and without MM are combined with the finite impulse response (FIR) filter which can reduce the error caused by the PBMM procedure. In the tests, plastic optical fiber (POF) displacement sensors are introduced and used as reference measurements to compare the dynamic displacement results from the proposed vision-based method. Compared with the measured displacements with POF sensors, the proposed method offers high level of accuracy for full-field displacement measurement.

Exposing a fibre-based dual-readout calorimeter to a positron beam

A prototype of a dual-readout calorimeter using brass capillary tubes surrounding scintillating and clear plastic optical fibres was tested using beams of particles with energies between 10 and 100 GeV produced by the CERN SPS. The scope of the test was to characterise the performance of the tube-based detector response to positrons in terms of response linearity, energy resolution, and lateral granularity. After calibrating the detector and processing the output signal to correct for the energy dependency on the particle impact point, the linearity of the measurement was found to be better than 1%. The response to positron was compared to that predicted by a Geant4-based simulation, finding good agreement both in terms of energy resolution and shower profile. These results confirm the validity of the tube-based mechanical option and SiPM readout as a promising one for future developments.

Sensing Approaches Exploiting Molecularly Imprinted Nanoparticles and Lossy Mode Resonance in Polymer Optical Fibers.

In this work, two different lossy mode resonance (LMR) platforms based on plastic optical fibers (POFs) are developed and tested in a biochemical sensing scenario. The LMR platforms are based on the combination of two metal oxides (MOs), i.e., zirconium oxide (ZrO2) and titanium oxide (TiO2), and deposited on the exposed core of D-shaped POF chips. More specifically, two experimental sensor configurations were obtained by swapping the mutual position of the Mos films over to the core of the D-shaped POF probe. The POF-LMR sensors were first characterized as refractometers, proving the bulk sensitivities. Then, both the POF-LMR platforms were functionalized using molecularly imprinted nanoparticles (nanoMIPs) specific for human transferrin (HTR) in order to carry out binding tests. The achieved results report a bulk sensitivity equal to about 148 nm/RIU in the best sensor configuration, namely the POF-TiO2-ZrO2. In contrast, both optical configurations combined with nanoMIPs showed an ultra-low detection limit (fM), demonstrating excellent efficiency of the used receptor (nanoMIPs) and paving the way to disposable POF-LMR biochemical sensors that are easy-to-use, low-cost, and highly sensitive.

Plastic Optical Fiber Integrated With Smartphone for Gait Monitoring

Plastic Optical Fiber Integrated With Smartphone for Gait Monitoring

Optical Communication and Positioning Convergence for Flexible Underwater Wireless Sensor Network

This paper presents a novel scheme based on underwater optical wireless communication and positioning (UOWC-UOWP) for an underwater wireless sensor network (UWSN). A dual-hop system is adopted to extend the limited coverage area of the UWSN with mobile nodes, consisting of a grade-index plastic optical fiber (GI-POF) link and a wireless link. Specifically, the mini-LED offers high-speed and flexible uplink transmission and the high-power LED enables both downlink transmission and positioning. The time frame design and code division multiplexing access (CDMA) support multi-user signal transmission. Proof-of-concept experiments with GI-POF and wireless link demonstrate the feasibility of the proposed scheme, which offers full-duplex communication, high-precise positioning and extended distance. To the best of our knowledge, the UOWC-UOWP convergent system is proposed for the first time. It has great potential to support high-capacity transmission between mobile nodes for future underwater transmission scenarios.

Miniature GaN optoelectronic temperature sensor.

The combination of plastic optical fiber (POF) with monolithically integrated transmitter and receiver is becoming increasingly attractive for the development of miniature optoelectronic sensing systems. Here, we propose a temperature sensing system by integrating a GaN optoelectronic chip with a POF and aluminum (Al) reflector. Owing to the overlap between electroluminescence and responsivity spectra of multiple quantum well (MQW) diodes, both the transmitter and the receiver having identical MQW structures are monolithically integrated on a tiny GaN chip by using the same fabrication process flow. Environmental temperature change leads to thermal deformation in the Al reflector, which reflects the transmitted light back with a light pulse. The reflected light is coupled into the guided POF again and sensed by the on-chip receiver. Finally, the temperature information is read out as electrical signals. When the ambient temperature changes from 20.1°C to 100°C, the optically induced electrical signal decreases from -3.04 µA to -3.13 µA. The results suggest that the monolithically integrated GaN device offers a promising option for optoelectronic temperature sensing systems.

Synthesis of graphene oxide-coated silver nanoparticles modified plastic of fibre optic sensor configuration

This paper presents the synthesis and fabrication of a sensor configuration using graphene oxide (GO) loaded with silver nanoparticles (AgNPs) on a conventional plastic optical fibre (POF) probe. A successful synthesis of GO and AgNPs was achieved using modified Hummers and seed-mediated methods, respectively. The POF was unclad using mechanical slicing and chemical etching, followed by the coating of GO-AgNPs via the dipping method. Scanning electron microscopy (SEM) analysis confirmed the successful coating, with 60% v/v acetone identified as the optimal etching solution. The clear evidence of embedded GO-AgNPs on the POF surface demonstrates the successful fabrication of a coating layer, establishing it as a promising sensing platform for optical fibre sensors.

Machine Learning-based reconstruction of single and double radiation source distribution using plastic scintillation optical fiber

In this study, we propose a novel method for reconstructing the radiation distribution of a one-dimensional radioactive source using Machine Learning (ML) algorithms and plastic scintillation optical fiber. The wavelength spectrum unfolding technique is used to estimate the source position accurately. We compare the accuracy and time efficiency of three different algorithms, namely, Generalized reduced gradient (GRG), Maximum likelihood expectation maximization (MLEM), and ML, in the single-source and dual-source cases. Our results demonstrate that MLEM algorithm has a shorter reconstruction time with comparable accuracy of position and intensity compared to GRG algorithm for single-source case. For dual-source case, ML algorithm provides real-time estimation of position and intensity with acceptable errors, while GRG algorithm has a larger error in intensity estimation and longer computation time. Our proposed ML algorithms offer useful guidance for practical applications in radiation source location.

Long Period Grating Imprinted on a Flat-Shaped Plastic Optical Fiber for Refractive Index Sensing

A corrugated surface long period grating (LPG) was fabricated on a flat-shaped plastic optical fiber (POF) as a refractive index (RI) sensor by a simple pressing with the heat pressure and mechanical die press print method. The light propagation characteristics of an LPG imprinted on a multi-mode POF were analyzed by the method of geometrical optics. Theoretical and experimental results showed that the structural parameters of the sensor affected the RI sensing performance, and the sensor with a thinner flat thickness, a deeper groove depth of the corrugated surface LPG, and a longer LPG exhibited better RI sensing performance. When the POF with a diameter of 1 mm was pressed with the heat pressure to a flat shape with a thickness of 600 µm, an LPG with a period of 300 µm, a groove depth of 200 µm, and a length of 6 cm was fabricated on it, and the RI sensitivity of 1447%/RIU was obtained with a resolution of 5.494×10−6 RIU. In addition, the influences of the POF cladding, tilting of LPG, and bending of the sensing structure were investigated. The results demonstrated that after removing the cladding and tilting or bending the LPG, the RI sensing performance was improved. When the LPG imprinted on the flat-shaped POF was bent with a curvature radius of 6/π cm, the highest sensitivity of 6 563%/RIU was achieved with a resolution of 2.487×10−9 RIU in the RI range of 1.3330–1.4230. The proposed sensor is a low-cost solution for RI measurement with the features of easy fabrication, high sensitivity, and intensity modulation at the visible wavelengths.

MIP-Assisted 3-Hole POF Chip Faced with SPR-POF Sensor for Glyphosate Detection

The present study proposes the application of a recently developed optical–chemical sensor system to glyphosate detection. The device probes the refractive index variation in a chip based on a plastic optical fiber (POF) in which three orthogonal micro-holes were created and filled with an acrylic-based molecularly imprinted polymer (MIP). This sensitive chip, connected in series to a gold-coated SPR-POF platform, can modify the surface plasmon resonance (SPR) phenomena by exploiting the multimode characteristic of the POFs. Therefore, the gold film of the SPR-POF platform is not covered by the MIP layer, improving the sensor’s performance because the interaction between the analyte (glyphosate) and the polymer recognition cavities occurs in the core and not in the cladding of the waveguide. Indeed, the sample solution is dropped on the MIP-based chip while a water drop is constantly maintained above the gold surface of the reference SPR-POF platform to excite the surface plasmons, modulated by the MIP interaction with the target analyte. The device is here for the first time applied for glyphosate sensing in water samples. The high sensitivity and selectivity are proven, and tests on real samples highlight the good performances of the developed sensors.