U-bent Plastic Optical Fiber Research Articles

U-Bent Plastic Optical Fiber Sensor for Iron in Iron Supplements

In this paper, we have designed a U-bent fiber optic sensor based on evanescent wave absorption for iron detection and quantification in the iron tablet. A detailed investigation of the impact of the bend-induced material deformation on the refractive index losses, numerical aperture, light propagation inside core and absorption coefficient has been presented. The experiment results of the developed sensor demonstrate the sensor sensitivity as 0.0316 O. D/ppm with a linear regression coefficient (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) of 98.1%.

U-bent Plastic Optical Fiber for Lard Adulteration Sensor in Edible Oil

A plastic optical fiber with the structure of U-bent was utilized as a sensor to detect lard adulterants in olive oil. The macro bending was formed on the plastic optical fiber with a bending radius of 10 mm, 12.5 mm, and 15 mm. The output spectra and intensity were measured to detect the existence of lard substance in olive oil. The U-bent plastic optical fiber sensor with a bending radius of 12.5 mm has the optimum performance to detect the lard adulterant substance in olive oil. It has a sensitivity of 4.6 a.u/% with 855 nm LED source and 10.07 a.u/% with 940 nm LED source in intensity-based measurement and 0.50 nm/% in spectrum-based measurement. The proposed sensor is the potential to give rapid detection on lard adulterant in edible oil.

Calibration and Uncertainty Evaluation of a Measurement System Using MLE: Application to a U-Bent RI POF-Sensor

In measurement systems, it is essential to have a procedure to obtain not only the calibration curve but also its associated uncertainty for the entire operating range. To achieve it, different alternatives should be taken into account according to the characteristics of the measurement, the way they are taken, the repeatability and reproducibility of the experiments or the nature of the measurement itself. This work presents a step-by-step procedure, to obtain simultaneously the calibration and uncertainty curves of a measurement system, which takes advantage of the maximum likelihood estimation (MLE), the weighted least squares (WLS) method, and the ISO-28037 recommendations. As an application, a U-Bent plastic optical fiber (POF) sensor measuring the sucrose solution density related to the refractive index (RI) is implemented and calibrated according to the proposed procedure.

Development of a U-bent plastic optical fiber biosensor with plasmonic labels for the detection of chikungunya non-structural protein 3.

This study presents a novel plasmonic fiber optic sandwich immunobiosensor for the detection of chikungunya, an infectious mosquito-borne disease with chronic musculoskeletal pain and acute febrile illness, by exploiting non-structural protein 3 (CHIKV-nsP3) as a biomarker. A plasmonic sandwich immunoassay for CHIKV-nsP3 was realized on the surface of a compact U-bent plastic optical fiber (POF, 0.5 mm core diameter) with gold nanoparticles (AuNPs) as labels. The high evanescent wave absorbance (EWA) sensitivity of the U-bent probes allows the absorption of the light passing through the fiber by the AuNP labels, upon the formation of a sandwich immunocomplex of CHIKV-nsP3 on the core surface of the U-bent probe region. A simple optical set-up with a low-cost green LED and a photodetector on either end of the U-bent probe gave rise to a detection limit of 0.52 ng mL-1 (8.6 pM), and a linear range of 1-104 ng mL-1 with a sensitivity of 0.1043A530 nm/log(CnsP3). In addition, the plasmonic POF biosensor shows strong specificity towards the CHIKV-nsP3 analyte in comparison with Pf-HRP2, HIgG, and dengue whole virus. The results illustrate the potential of plasmonic POF biosensors for direct and sensitive point-of-care detection of the chikungunya viral disease.

U-bent plastic optical fiber probes as refractive index based fat sensor for milk quality monitoring

Abstract Milk fat content is an important parameter for milk quality assessment in the dairy industry. This study reports the development of a hand-held, highly sensitive fiber optic milk fat sensor using U-bent plastic optical fiber (POF) probes based on the refractive index (RI) of milk, an inherent physicochemical property of milk, which is significantly influenced by the milk fat content. The U-bent POF sensor probes facilitate dip type sensing and offer non-destructive assessment of milk quality in real-time. The sensor works on the principle of intensity modulation technique by exploiting evanescent wave absorbance and refractive losses. The fiber optic probes sense a change in RI of the medium as a result of attenuated total reflection by virtue of the evanescent wave interactions of light at the fiber core/cladding interface with the surrounding medium. A relative change in the refractive index property of milk as a result of variation in fat content and addition of water is investigated using U-bent POF probes for milk quality assessment. The sensor shows an optical absorbance sensitivity of 0.15 ΔA/Δ% fat for the variation of fat content in the milk. Besides, the response of the sensor to water addition in wide concentration range was studied. Furthermore, a low cost portable optoelectronic device is reported for instantaneous milk quality monitoring in farm fields. This sensor could be of huge potential in dairy industries, milk collection centers as well as end-user applications for real-time milk quality monitoring.

Graphene oxide coated U-bent plastic optical fiber based chemical sensor for organic solvents

This study describes the development of a refractive index (RI) based fiber optic chemical sensor using a U-bent plastic optical fiber (BPOF) probe made of 0.5 mm polymethylmethacrylate (PMMA) core and optimum bend diameter of 1.4 mm coated with graphene oxide (GO) film. GO film on BPOF sensor surface significantly enhance the RI sensitivity of the sensor as well as its chemical resistance due to improved refractive index contrast and (PMMA) surface passivation by GO respectively. GO was chemisorbed to hexamethylenediamine (HMDA) functionalized BPOF probe surface by identifying the optimum GO concentration (100 μg/ml) and incubation time (24 h). An enhanced RI sensitivity of 9.42 ± 0.37 (ΔA845nm/ΔRIU) was achieved using GO coating of thickness 3.3 μm, which is 3.6 times higher than that of the bare BPOF probe. The RI sensitivities in presence of organic solvents including methanol, ethanol and isopropyl alcohol are found to be 12.75 ± 1.19, 9.97 ± 0.66 and 13.93 ± 0.92 (ΔA845nm/ΔRIU) respectively. GO film over BPOF was stable even after incubation of the probes in the alcohols over 12 h. In addition, GO-BPOF probes were able to tolerate acetone environment for a prolonged duration of 30 min as opposed to 10 min in case of the bare probes due to improved chemical resistance. Hence, the GO-BPOF could potentially be utilized as a sensitive RI sensor not only for aqueous solutions but also for reactive organic solvents such as alcohols and acetone which are known to damage the PMMA surface.

Gold Sputtered U-Bent Plastic Optical Fiber Probes as SPR- and LSPR-Based Compact Plasmonic Sensors

This study describes fabrication of highly sensitive surface plasmon resonance (SPR) as well as localized SPR (LSPR) dominant fiber optic plasmonic probes by controlled sputtering of gold thin films on the fiber core surface. Compact U-bent probes of 750 μm plastic optical fibers (made of poly(methylmethacrylate) (PMMA)) were used for efficient evanescent wave excitation of plasmonic substrates to achieve high sensitivity. U-bent probes with 2.25-mm bend diameter were sputter coated for deposition times of 30, 60, 90, and 120 s to obtain gold thin films with nanovoids on the U-bent region. As deposition time increased, a significant transition from LSPR to SPR characteristics was observed in the overall UV-visible spectral characteristics with a clear shift in the plasmon peak from 520 to 650 nm. Probes sputtered for 30 and 120 s show excellent LSPR- and SPR-based characteristics with a sensitivity of 15.5 ∆Abs/RIU and 1040 nm/RIU, respectively (for refractive index variation from 1.333 to 1.361 RIU). The high sensitivity of the probes in addition to other advantages, including ease of fabrication, cost-effectiveness, and suitability for in situ monitoring, demonstrates their potential for bio/chemical sensing applications.

Development of LSPR based U-bent plastic optical fiber sensors

This study presents design and development of evanescent wave absorbance based U-bent plastic optical fiber (POF) probe with high sensitivity and its applications to refractive index (RI) sensing. The probes were fabricated by a controlled decladding procedure to remove the fluorinated polymer without damaging the poly methyl methacrylate (PMMA) core and a simple and scalable fabrication technique to obtain POF U-bent probes of desired geometry. U-bent probes of fiber diameter from 250 to 1000μm were fabricated and optimum bend diameter for each fiber diameter was investigated. The sensitivity was found to be maximum when the bend diameter of the probe varies from 2 to 3 times the fiber diameter. Probes with 500μm core and 1.25mm bend diameter showed highest sensitivity (5.57ΔA560nm/ΔRIU) in the visible region to RI changes from 1.33 to 1.47 with a resolution better than 1 milli RI units. Furthermore, U-bent probes were amine functionalized and coated with gold nanoparticles to obtain a localized surface plasmon resonance (LSPR) based RI sensor that has an 8-fold improvement in RI sensitivity, hence extending their applicability to plasmonic biosensing.