Surface Of Optical Fiber Research Articles

S-shaped tellurite optical fiber surface plasmon resonance sensor for temperature and refractive index measurement

In this paper, an all-fiber S-shaped structure optical fiber surface plasmon resonance (SPR) sensor is proposed for temperature and refractive index measurement. The sensor is made of a single-mode tellurite optical fiber (TOF), and the middle part of the single-mode TOF is heated by a ceramic heating rod to form an S-shaped sensing region, and a 50 nm gold film is deposited in the S-shape sensing area to excite SPR. Based on the excellent properties of tellurite optical fiber, the prepared optical fiber sensor can be used for high sensitivity temperature and refractive index detection. The highest refractive index sensitivity is up to 1068.59 nm/RIU in the range of 1.333–1.380, and the temperature sensitivity is up to −0.713 nm/°C in the range of 30–150 °C. The proposed sensor is simple to fabricate, low-cost, and compact, and can be widely used in biochemical analysis, complex environmental temperature monitoring and other fields.

Corrosive Pseudomonas aeruginosa detection by measuring pyocyanin with a lab-on-fiber optical surface plasmon resonance biosensor in aquatic environments

Oceanic facilities and equipment corrosion present considerable economic and safety concerns, predominantly due to microbial corrosion. Early detection of corrosive microbes is pivotal for effective monitoring and prevention. Yet, traditional detection methods often lack specificity, require extensive processing time, and yield inaccurate results. Hence, the need for an efficient real-time corrosive microbe monitoring technology is evident. Pseudomonas aeruginosa, a widely distributed microorganism in aquatic environments, utilizes its production of quinone-like compounds, specifically pyocyanin (PYO), to corrode metals. Here, we report a novel fiber optic surface plasmon resonance (SPR) sensor modified by the C-terminal of BrlR protein (BrlR-C), which is a specific receptor of PYO molecule, to detect P. aeruginosa in aquatic environments. The results showed that the sensor had a good ability to recognize PYO in the concentration range of 0–1 μg/mL, and showed excellent sensing performance in real-time monitoring the growth status of P. aeruginosa. With a strong selectivity of PYO, the sensor could clearly detect P. aeruginosa against other bacteria in seawater environment, and exhibited excellent anti-interference ability against variations in pH, temperature and pressure and other interfering substances. This study provides a useful tool for monitoring corrosive P. aeruginosa biofilm in aquatic environments, which is a first of its kind example that serves as a laboratory model for the application of fiber optic technology in real-world scenarios to monitoring biofilms in microbial corrosion and biofouling.

Fiber Optic LSPR Sensing AFM1 in Milk with Enhanced Sensitivity by the Hot Spot Effect Based on Nanogap Construction.

The detection of the amount of aflatoxin M1 (AFM1) in milk is crucial for food safety. Here, we utilize a fiber optic (FO) localized surface plasmon resonance (LSPR) biosensor by constructing gold nanoparticle (AuNP) multimers, in which the nanogaps amplified the LSPR signal by the hot spot effect, and achieved a highly sensitive detection of f AFM1. Through the optimization of parameter conditions for the fabrication of the sensor and detection system, a high performance result from the FO LSPR biosensor was obtained, and the method for AFM1 detection was established, with a wide detection range of 0.05-100 ng/mL and a low limit of detection (LOD) of 0.04 ng/mL, and it has been successfully validated with the actual sample milk. Therefore, it is a good strategy to fabricate highly sensitive FO LSPR sensors for detecting AFM1 by constructing AuNP multimers, and this approach is suitable for developing other biosensors.

Hydrogel binding sodium alginate based optical fiber surface plasmon resonance for calcium ion trace detection

A plasmonic tilted fiber Bragg grating (TFBG)-based sensor for the detection of calcium ion (Ca2+) was proposed and demonstrated experimentally. Hydrogel material was synthesized by utilizing hydrogen bond recombination between cellulose nanocrystals (CNC) and polyvinyl alcohol (PVA). Sodium alginate (SA) was incorporated into this hydrogel material, resulting in a composite membrane with specific binding properties for Ca2+. The membrane was applied as a coating on the surface of a gold-coated TFBG. The CNC/PVA-SA modified gold on the TFBG surface enhanced the localized refractive index changes caused by variations of Ca2+ concentrations. The experimental results demonstrated an impressive limit of detection (LOD) of approximately 0.025 fM, which is five orders of magnitude better than the current LODs of similar Ca2+ sensors. And the proposed Ca2+ sensor exhibited a wide dynamic range of 10−16 M to 10−6 M.

Temperature self-compensated fiber-optic Pb(II) sensor with improved selectivity by Resorcylaldehyde post-modified organic metal framework

Post-modification of metal-organic framework (MOF) materials is an effective means to enhance their efficient and selective adsorption for heavy metal ions. In this article, we presented a reflection-type optical fiber surface plasmon resonance (SPR) sensor based on dual core fiber (DCF) coated with UiO-66-RSA (UiO-66-NH2 post-modified with resorcinol aldehyde) film for the specific detection of Pb(II) in aqueous media. The composite material UiO-66-RSA exhibits stronger affinity and specificity for Pb(II) than UiO-66-NH2. The adsorption of Pb(II) can change the equivalent refractive index (RI) of UiO-66-RSA film, causing a regular shift in SPR spectra. Experiments have shown that the limit of detection (LOD) of the SPR Pb(II) sensor can reach 0.1 nM. Meanwhile, research has found that the SPR sensor is accompanied by temperature crosstalk of 0.356 nm/°C. Therefore, we constructed a Michelson temperature interferometer using polymer micro tips on the end face of the fiber core to achieve temperature compensation. Based on the above two sensing channels, dual parameter demodulation of Pb(II) concentration and temperature can be achieved with an error rate of less than 0.5 %. This article has potential research value in exploring the application of post modification techniques of MOF in fiber optic lead ion detection.

All fiber Mach-Zehnder interferometer immunosensor based on rabbit anti-human IgG and protein a for human IgG detection

Antibodies produced by the immune system, including immunoglobin G (IgG), are among the important biological biomarkers. Optical fibers are ideal for fabricating biosensors because of their flexibility, weight, biocompatibility, electromagnetic interference immunity, etc. This study proposes a multimode-single mode-multimode (MSM) Mach-Zehnder interferometer immunosensor based on rabbit anti-human IgG and protein A (PA) for human IgG detection. When IgG is trapped by antibodies located on the surface of the fiber, the refractive index (RI) changes, and the wavelength redshift occurs in the transmission spectrum of the interference pattern. Here, for binding the antibody to the pre coated PA surface, a rabbit anti-human IgG has been used, which has stronger binding to PA and as a result higher stability than the goat anti-human IgG on the optical fiber surface. By optimizing the optical configuration and biolayer material, a limit of detection of 0.067 μg/ml and sensitivity of 0.14 nm.ml/μg could be achieved.

Light transmission in knitted fabrics through polymeric optical fiber insertion for advanced textile applications

Smart textiles are prominent in the textile industry, with applications in various technical areas such as medicine, architecture, sports, and esthetic purposes, among others. Within this concept, optical fibers are classified as passive smart textiles and are highly attractive for clothing lighting and monitoring physiological parameters. This study aimed to present methods for inserting polymeric optical fibers into weft single knitted fabrics and verifying the loss of luminosity in them, analyzing the technical feasibility of developing e-textiles to be applied in monitoring. For such, weft knitted fabrics were produced by altering the optical fiber insertion methodology, defined as inlay insertion and insertion in the course direction, each subdivided into different methods. Light transmission was verified using a laser pen connected to the optical fiber. Images were captured and analyzed using LILP software to verify and quantify the loss of luminosity in each insertion method. Light transmission microscopy was performed to evaluate the surface of the polymeric optical fiber used. For the insertion techniques performed, inlay and by course direction, the result obtained for signal transmission was satisfactory; however, the inlay insertion methods presented lower light emission but lower luminosity loss than the insertion by course direction. This result is very interesting because it enables the development of weft knitted fabrics from the use of optical fibers for application in various types of monitoring.

Improving radio frequency heating uniformity in peanuts: Effects of packaging geometry, electrode gap, particle size and interlayer displacement process

This study aimed to assess the impact of various processing parameters including electrode gap, packaging geometry, and particle size on the heating efficiency of radio frequency (RF) processing for peanut thermal decontamination. In addition, interlayer displacements were presented to evaluate the effect of the mixing on heating uniformity.Experimental studies were carried out using 3D-printed polylactic acid (PLA) containers (square, rectangular, and cylindrical) to place the peanut samples with particle sizes ranging from 0.71 to 2.00 mm at 100–140 mm electrode gaps. Temperature changes within the samples were monitored using fiber optic sensors and surface temperature distributions were determined with an infrared camera. Heating uniformity index (λ) was then calculated to assess the effects of RF processing conditions on RF heating uniformity.Results showed that the cylindrical container exhibited a more consistent and uniform heating profile (λ = 0.12) with 1.58 °C min−1 heating rate compared to other containers, and a single interlayer displacement between top and bottom layers further improved temperature distribution uniformity. Smaller particle sizes also led to faster heating rates from 1.71 to 1.55 °C min−1 with more uniform heating due to the reduced porosity within the particles with increased thermal conduction and electromagnetic energy absorption. This study presented valuable insights for developing an effective RF process as an alternative to conventional thermal treatments for decontamination of low-moisture, high-fat particulate foods. Industrial significanceThis research presented an innovative approach applying RF heating for a possible decontamination process for peanut samples. The research tackled the growing worldwide consumer demand for food products to satisfy food safety regulations while peanuts were selected to demonstrate the process effect due to the recent food safety issues in peanut butter considering that a pre-process for decontamination would lead to a decrease in the resulting safety issues.

Hetero-core fiber-optic surface plasmon resonance sensor with ionic liquid gel coating for CO2 sensing

Fiber-optic CO2 sensors are free of electromagnetic interference and highly resistant to corrosion but often require expensive measurement systems or sophisticated preparation procedures. To address this challenge, we developed a CO2 sensor comprising a hetero-core fiber-optic surface plasmon resonance sensor coated with an ionic liquid (IL) gel as a cost-effective CO2 sensing system. Among the various sensors tested, the sensor using ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) as the IL, prepared at a pull-up speed of 4.5 mm s−1, showed the best CO2 sensing performance. A hybrid membrane of [EMIM][BF4] and a CO2-absorbing polymer (monoethanolamine) demonstrated higher sensitivity for CO2 concentrations ranging from 0 to 100%. The highlight of the proposed system is its low-cost configuration comprising an 850 nm-wavelength LED and a photodiode as the light source and signal detection device, respectively. Along with facile preparation and low-cost system configuration, the proposed system exhibited significant potential for CO2 sensing in various fields.

Reflective optical fiber SPR sensor with DNA modification for high-sensitive Hg2+ concentration measurement

A reflective optical fiber surface plasmon resonance (SPR) sensor was proposed to measure the concentration of mercury ions (Hg2+). The specific single-stranded DNA was modified on the optical fiber sensing surface coated with Au film by the combination of covalent bond and charge adsorption. The Hg2+ can mismatch with T-T (thymine-thymine) base pairs in single-stranded DNA to form T-Hg2+-T structure, which led to the change of refractive index in sensing area and the wavelength shift of SPR spectrum. The measurement results showed that when the concentration of Hg2+ increased from 0 μM to 13 μM, the resonance spectrum shifted by 14.26 nm. In the linear range between 1–8 μM, the measurement sensitivity of the sensor could reach 1.51 nm/μM. The limit of detection (LOD) was found to be 0.28 μM. Besides, the sensor showed good stability, selectivity and reusability.

Operando Decoding of Surface Chemical and Thermal Events in Photoelectrocatalysis via a Lab-Around-Microfiber Sensor.

Operando decoding of the key parameters of photo-electric catalysis provides reliable information for catalytic effect evaluation and catalytic mechanism exploration. However, to capture the details of surface-localized and rapid chemical and thermal events at the nanoscale in real-time is highly challenging. A promising approach based on a lab-around-microfiber sensor capable of simulating photo-electric catalytic reactions on the surface of optical fibers as well as monitoring reactant concentration changes and catalytic heat generation processes is demonstrated. Due to the penetration depth of submicron size and the fast response ability of the evanescent field, the lab-around-microfiber sensor overcame the difficulty of reading instantaneous surface parameters in the submicron range. This sensor operando dismantled the changes in reactant concentration and temperature on the catalyst surface induced by light and voltage, respectively. It also decoded the impact of catalyst composition on the adsorption efficiency and catalytic efficiency across various wavelengths and determined the synchronized occurrence of pollutant degradation and catalytic thermal effects. Stable correlations between the real-time parameters and catalytic activities are obtained, helping to provide a basic understanding of the catalytic process and mechanism. This approach fills an important gap in the current monitoring methods of catalytic processes and heat production.

Performance comparison of different filters based on fibre optic lighting systems and evaluation of architectural lighting effects

Plastic optical fiber lighting is a feasible green lighting method for buildings. This study first derives a mathematical model for the focused light energy absorbed by optical fibers. Based on the variable relationships in the mathematical model, the cooling mechanism of plastic optical fibers was obtained. Secondly, a dual-axis automatic sun-tracking concentrating lighting equipment capable of carrying nine Fresnel lenses was designed. The equipment was used to compare the filtering and cooling effects of two types of filter devices: infrared filters and heat-insulating film. The cooling and lighting effects of these two types of filter devices were also evaluated. Subsequently, the impact of fiber loops on lighting was discussed. Finally, the b2 and b3 modules of the dual-axis automatic sun-tracking concentrating lighting equipment were applied in dark stairwells. The results indicate that the temperature of optical fibers can be reduced by using filtering devices and enhancing heat radiation and convection on the surface of optical fibers. Infrared filters exhibit better cooling and lighting effects than heat-insulating film. Looping the fiber cable reduces the effect of fiber lighting, and the higher the number of loops, the higher the loss of fiber lighting. The dual-axis automatic sun-tracking concentrating lighting equipment increased the illuminance value in the stairwells to over 50 lux, showing great application potential in architectural lighting.

Design and optimization of a flexible fiber-conducted laser light guide plate system

As the demand for slim liquid crystal displays (LCDs) continues to rise in the lighting and visual display fields, the edge-lit backlight structure has received significant attention. However, the edge-lit backlight structure cannot function properly without a light guide plate (LGP) system. This study proposes a novel LGP system employing a laser as the light source and utilizing optical fiber as a waveguide. The design transmits a laser beam into the LGP through an optical fiber, adds microstructure and reflective surfaces, and optimizes the layout of the microstructure. Under the condition that a single point light source is used as the incident light source of the system, the illumination uniformity of the light output surface is finally realized to be as high as 95.8 %, and the light transmission efficiency is as high as 79.7 %. Next, the light output performance of the LGP was measured in the case of single-point light entry on the short side of the strip LGP, and the difference between the test results and the simulation data was within 5 %. The system adopts the fiber optic transmission method of electro-optical separation, which has certain application prospects in the fields of underwater detection, decorative lighting and urban landscape.

A film composed of PEDOT:PSS/PVA as a sensitive medium for pH sensor in optical fiber

In this work, a pH sensitive transducer element attached to a multimode optical fiber section is proposed. The sensitive element is a PEDOT:PSS/PVA composite film that exhibited sensitivity at low pH values in the range of 1–7 pH. The addition of PVA was important for the adhesion process to the optical fiber surface. The morphology of the PEDOT:PSS polymers allowed characterization at pH stimuli that were based on the optical power transmission generated from the interaction of the light propagating in the optical fiber core and the optical fiber section coated with the sensitive film. A sensitivity of −0.05 dB/pH and a linear fit R2 of 0.93 was obtained, the response time was 3 s, while the sensor recovery time was 50 s maintaining stability higher than 10 min.

FO-SPR Model for Full-Spectrum Signal Analysis of Back-reflecting FO-SPR Sensors to Monitor MOF Deposition.

In this study, we explore the full-spectrum capabilities of fiber-optic surface plasmon resonance (FO-SPR) for analyzing heterogeneous samples with increased comprehensiveness. Our approach involves refining a literature-derived FO-SPR model to more precisely reflect experimental data obtained using a back-reflecting sensor configuration. Key enhancements in our model include adjustments to the thickness and permittivity of the gold SPR-active layer on the FO-SPR sensor as well as improvements to the angular distribution of light within the system. We apply this optimized model to the investigation of the deposition process of a metal-organic framework (MOF), specifically ZIF-8, using FO-SPR. By closely examining the temporal variations in the FO-SPR signal during MOF layer formation, we simultaneously determine the evolving thickness and refractive index (RI) of the MOF layer, offering a dual-parameter analysis. Our results demonstrate that a full-spectrum analysis of the FO-SPR signal can extract critical information from samples exhibiting radial heterogeneity. This advancement significantly enhances the quantitative assessment of various phenomena that alter the refractive index in the sensor's domain, such as adsorption and binding processes. This work thus represents a significant step forward in the field of FO-SPR sensor technology, promising broad applications in areas requiring the precise detection and analysis of complex samples.

Sodium-based no-core fiber surface plasmon resonance sensor with high sensitivity and narrow FWHM

Since fiber-optic sensors using noble metal-excited surface plasmon resonance (SPR) effects have encountered bottlenecks in improving performance, we propose a fiber-optic sensor using sodium in combination with a no-core fiber (NCF) to measure both refractive index (RI) and temperature. We deposited sodium thin films on the surface of NCF optical fibers and protected them with polymethyl methacrylate (PMMA) or polydimethylsiloxane (PDMS) for RI sensing or temperature sensing. We performed computational simulations and performance analyses of the sensors using the finite element method, and the results show that the sodium-based SPR sensors have higher sensitivity, wider detection range, and narrower full width at half-maximum (FWHM) than the noble metal SPR sensors. SPR sensors with different sodium film thicknesses have different sensing characteristics, so we can get optical fiber sensors with more flexible transmission characteristics, which helps us arrange sensors more conveniently in practical applications. The simulation and numerical results show that when the sensor is used to measure RI, the average sensitivity of the sensor can reach 7977 nm RIU−1, the maximum sensitivity can reach 23100 nm RIU−1, the narrowest FWHM is 14.23 nm, and the maximum figure of merit (FOM) is 719.42 RIU−1 under different thicknesses of sodium film. The corresponding RI ranges from 1.32 to 1.41. When the temperature measurement range is 0 °C ∼ 100 °C, the average sensitivity can reach 7.86 nm °C−1, the maximum temperature sensitivity can reach 21.1 nm °C−1, and the narrowest FWHM is 17.84 nm. In summary, the proposed sodium-based SPR sensor has flexible and high-performance sensing characteristics, and our research work provides more powerful theoretical support for the application of sodium-based plasma devices.

Smartphone-based selective and sensitive detection of vitamin B1 in synthetic urine using U-bend SPR optical fiber probe

This paper introduces an innovative optical fiber surface plasmon resonance (SPR) biosensor designed for smartphone assistance, aiming at detecting vitamin B1 in synthetic urine. The key novelty lies in the amalgamation of silver nanocoated cysteine with a gold-plated optical fiber probe, fostering efficient detection through the robust electrostatic interaction between negatively charged Cys-capped AgNPs and positively charged vitamin B1 molecules. Notably, this biosensor leverages the smartphone's digital camera capabilities to discern varying color intensities. A self-developed application ensures real-time monitoring of green and red channel intensities in the SPR signal, thereby mitigating the risk of false detections. Moreover, the integration of the fabricated optical fiber probe with the smartphone is achieved through a 3D-printed casing, endowing the biosensor with the advantages of portability, handheld operation, and cost-effectiveness. The proposed U-shaped optical fiber SPR biosensor, coupled with smartphone technology, demonstrates the ability to detect vitamin B1 within the concentration range of 2–10 μM, yielding a commendable R2 value of 0.9973. Experimental findings affirm that this novel biosensor, built on the U-shaped SPR optical fiber architecture and empowered by smartphones, is an economical, uncomplicated, and portable device adept at accurately and efficiently detecting vitamin B1 across a broad concentration spectrum. Its potential applications extend to the area of low-cost biochemical component identification.

Analysis of Tapered Fiber-Optic Surface Plasmon Resonance (SPR) Bio-Sensing Probe With the Effect of Different Taper Profiles and Metal Choices

Analysis of Tapered Fiber-Optic Surface Plasmon Resonance (SPR) Bio-Sensing Probe With the Effect of Different Taper Profiles and Metal Choices

Efficient Sequential Detection of Two Antibiotics Using a Fiber-Optic Surface Plasmon Resonance Sensor.

Antibiotic residues have become a worldwide public safety issue. It is vital to detect multiple antibiotics simultaneously using sensors. A new and efficient method is proposed for the combined detection of two antibiotics (enrofloxacin (Enro) and ciprofloxacin (Cip)) in milk using surface plasmon resonance (SPR) sensors. Based on the principle of immunosuppression, two antibiotic antigens (for Enro and Cip) were immobilized on an optical fiber surface with conjugates of bovine serum albumin using dopamine (DA) polymerization. Each single antigen was bound to its corresponding antibody to derive standard curves for Enro and Cip. The fiber-optic sensor's sensitivity was 2900 nm/RIU. Detection limits were calculated to be 1.20 ng/mL for Enro and 0.81 ng/mL for Cip. The actual system's recovery rate was obtained by testing Enro and Cip in milk samples; enrofloxacin's and ciprofloxacin's mean recoveries from the milk samples were 96.46-120.46% and 96.74-126.9%, respectively. In addition, several different regeneration solutions were tested to analyze the two target analytes' regeneration ability; NaOH and Gly-HCl solutions were found to have the best regeneration ability.

Green synthesis of Ag/Yb2O3 nanostructures based-MIP for tamoxifen detection: Advancing from refractometers to sensor

This study presents a novel optical fiber refractometer based on a single smart functional layer of Ag/Yb2O3 nanostructure, synthesized by a green chemistry method using oak fruit extract. The optical phenomena of surface plasmon resonance (SPR) and lossy mode resonance (LMR) were investigated based on the performance of the real and imaginary parts of the dielectric constant function of nanoparticles and nanostructures coated on the optical fiber. The Ag/Yb2O3 nanostructure enhances the LMR phenomenon and acts as an electron mediator for the detection of tamoxifen (TAM) drug, a widely used anticancer agent. The Ag/Yb2O3 nanostructure was coated on a curved optical fiber surface along with a molecularly imprinted polymer (MIP) layer, which provided selective recognition of TAM molecules. The sensor probe showed rapid and reversible adsorption/desorption of TAM, with a high sensitivity of 5.3611 nm/µM and a limit of detection (LOD) and limit of quantification (LOQ) of 0.0987 μM and 0.32902 μM, respectively. The sensor also exhibited good recovery rate and effectiveness in real samples, demonstrating its potential for sensivity applications.