Research

16 pages, 1099 KiB

Open AccessArticle

LSPR and Interferometric Sensor Modalities Combined Using a Double-Clad Optical Fiber

by Harald Ian Muri, Andon Bano and Dag Roar Hjelme

Sensors 2018, 18(1), 187; https://doi.org/10.3390/s18010187 - 11 Jan 2018

Cited by 12 | Viewed by 5069

We report on characterization of an optical fiber-based multi-parameter sensor concept combining localized surface plasmon resonance (LSPR) signal and interferometric sensing using a double-clad optical fiber. The sensor consists of a micro-Fabry-Perot in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold [...] Read more.

We report on characterization of an optical fiber-based multi-parameter sensor concept combining localized surface plasmon resonance (LSPR) signal and interferometric sensing using a double-clad optical fiber. The sensor consists of a micro-Fabry-Perot in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanorods on the facet of a cleaved double-clad optical fiber. The swelling degree of the hydrogel is measured interferometrically using the single-mode inner core, while the LSPR signal is measured using the multi-mode inner cladding. The quality of the interferometric signal is comparable to previous work on hydrogel micro-Fabry-Perot sensors despite having gold nanorods immobilized in the hydrogel. We characterize the effect of hydrogel swelling and variation of bulk solution refractive index on the LSPR peak wavelength. The results show that pH-induced hydrogel swelling causes only weak redshifts of the longitudinal LSPR mode, while increased bulk refractive index using glycerol and sucrose causes large blueshifts. The redshifts are likely due to reduced plasmon coupling of the side-by-side configuration as the interparticle distance increases with increasing swelling. The blueshifts with increasing bulk refractive index are likely due to alteration of the surface electronic structure of the gold nanorods donated by the anionic polymer network and glycerol or sucrose solutions. The recombination of biotin-streptavidin on gold nanorods in hydrogel showed a 7.6 nm redshift of the longitudinal LSPR. The LSPR response of biotin-streptavidin recombination is due to the change in local refractive index (RI), which is possible to discriminate from the LSPR response due to changes in bulk RI. In spite of the large LSPR shifts due to bulk refractive index, we show, using biotin-functionalized gold nanorods binding to streptavidin, that LSPR signal from gold nanorods embedded in the anionic hydrogel can be used for label-free biosensing. These results demonstrate the utility of immobilizing gold nanorods in a hydrogel on a double-clad optical fiber-end facet to obtain multi-parameter sensing. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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3984 KiB

Open AccessArticle

U-Shaped and Surface Functionalized Polymer Optical Fiber Probe for Glucose Detection

by Mikel Azkune, Leire Ruiz-Rubio, Gotzon Aldabaldetreku, Eneko Arrospide, Leyre Pérez-Álvarez, Iñaki Bikandi, Joseba Zubia and Jose Luis Vilas-Vilela

Sensors 2018, 18(1), 34; https://doi.org/10.3390/s18010034 - 25 Dec 2017

Cited by 28 | Viewed by 6982

Abstract

In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by [...] Read more.

In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by using a U-shaped geometry. Employing a supercontinuum light source and a high-resolution spectrometer, absorption measurements are performed in the broadband visible light spectrum. Experimental results suggest the feasibility of such a fiber probe as a low-cost and selective glucose detector. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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2830 KiB

Open AccessArticle

Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis

by Luis A. Herrera-Piad, Joseph W. Haus, Daniel Jauregui-Vazquez, Juan M. Sierra-Hernandez, Julian M. Estudillo-Ayala, Yanelis Lopez-Dieguez and Roberto Rojas-Laguna

Sensors 2017, 17(10), 2393; https://doi.org/10.3390/s17102393 - 20 Oct 2017

Cited by 10 | Viewed by 5665

Abstract

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data [...] Read more.

A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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1706 KiB

Open AccessArticle

High Sensitivity Refractometer Based on Reflective Smf-Small Diameter No Core Fiber Structure

by Guorui Zhou, Qiang Wu, Rahul Kumar, Wai Pang Ng, Hao Liu, Longfei Niu, Nageswara Lalam, Xiaodong Yuan, Yuliya Semenova, Gerald Farrell, Jinhui Yuan, Chongxiu Yu, Jie Zeng, Gui Yun Tian and Yong Qing Fu

Sensors 2017, 17(6), 1415; https://doi.org/10.3390/s17061415 - 16 Jun 2017

Cited by 17 | Viewed by 5947

Abstract

A high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional [...] Read more.

A high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional single mode fiber (SMF) and the end face of the SDNCF was coated with a thin film of gold to provide reflective light. The influence of SDNCF diameter and length on the refractive index sensitivity of the sensor has been investigated by both simulations and experiments, where results show that the diameter of SDNCF has significant influence. However, SDNCF length has limited influence on the sensitivity. Experimental results show that a sensitivity of 327 nm/RIU (refractive index unit) has been achieved for refractive indices ranging from 1.33 to 1.38, which agrees well with the simulated results with a sensitivity of 349.5 nm/RIU at refractive indices ranging from 1.33 to 1.38. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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2112 KiB

Open AccessArticle

A Point Temperature Sensor Based on Upconversion Emission in Er³⁺/Yb³⁺ Codoped Tellurite-Zinc-Niobium Glass

by Ting Wu, Rui Tong, Liwen Liao, Lihui Huang, Shilong Zhao and Shiqing Xu

Sensors 2017, 17(6), 1253; https://doi.org/10.3390/s17061253 - 31 May 2017

Cited by 19 | Viewed by 4785

Abstract

Er³⁺/Yb³⁺ codoped tellurite-zinc-niobium (TZNb) glass was prepared by the melt-quenching method and used for the construction of a point all-fiber temperature sensor. The glass thermal stability and network structural properties were studied by differential thermal analysis and Raman spectrum, respectively. [...] Read more.

Er³⁺/Yb³⁺ codoped tellurite-zinc-niobium (TZNb) glass was prepared by the melt-quenching method and used for the construction of a point all-fiber temperature sensor. The glass thermal stability and network structural properties were studied by differential thermal analysis and Raman spectrum, respectively. High glass transition temperature is beneficial to widen the working temperature range. The dependence of fluorescence intensity ratio (FIR) of green upconversion emissions on the surrounding temperature from 276 to 363 K was experimentally investigated and the maximum temperature sensitivity is 95 × 10⁻⁴ K⁻¹ at 363 K. Strong green upconversion emission, broad temperature measurement range and high sensitivity indicate this point temperature sensor is a promising optical device for application on optical temperature sensing. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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1634 KiB

Open AccessArticle

In-Fiber Optic Salinity Sensing: A Potential Application for Offshore Concrete Structure Protection

by Dong Luo, Peng Li, Yanchao Yue, Jianxun Ma and Hangzhou Yang

Sensors 2017, 17(5), 962; https://doi.org/10.3390/s17050962 - 04 May 2017

Cited by 10 | Viewed by 5111

Abstract

The protection of concrete structures against corrosion in marine environments has always been a challenge due to the presence of a saline solution—A natural corrosive agent to the concrete paste and steel reinforcements. The concentration of salt is a key parameter influencing the [...] Read more.

The protection of concrete structures against corrosion in marine environments has always been a challenge due to the presence of a saline solution—A natural corrosive agent to the concrete paste and steel reinforcements. The concentration of salt is a key parameter influencing the rate of corrosion. In this paper, we propose an optical fiber-based salinity sensor based on bundled multimode plastic optical fiber (POF) as a sensor probe and a concave mirror as a reflector in conjunction with an intensity modulation technique. A refractive index (RI) sensing approach is analytically investigated and the findings are in agreement with the experimental results. A maximum sensitivity of 14,847.486/RIU can be achieved at RI = 1.3525. The proposed technique is suitable for in situ measurement and monitoring of salinity in liquid. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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7690 KiB

Open AccessArticle

A Multi-Platform Optical Sensor for In Vivo and In Vitro Algae Classification

by Chee-Loon Ng, Qing-Qing Chen, Jia-Jing Chua and Harold F. Hemond

Sensors 2017, 17(4), 912; https://doi.org/10.3390/s17040912 - 20 Apr 2017

Cited by 7 | Viewed by 6653

Abstract

Differentiation among major algal groups is important for the ecological and biogeochemical characterization of water bodies, and for practical management of water resources. It helps to discern the taxonomic groups that are beneficial to aquatic life from the organisms causing harmful algal blooms. [...] Read more.

Differentiation among major algal groups is important for the ecological and biogeochemical characterization of water bodies, and for practical management of water resources. It helps to discern the taxonomic groups that are beneficial to aquatic life from the organisms causing harmful algal blooms. An LED-induced fluorescence (LEDIF) instrument capable of fluorescence, absorbance, and scattering measurements; is used for in vivo and in vitro identification and quantification of four algal groups found in freshwater and marine environments. Aqueous solutions of individual and mixed dissolved biological pigments relevant to different algal groups were measured to demonstrate the LEDIF’s capabilities in measuring extracted pigments. Different genera of algae were cultivated and the cell counts of the samples were quantified with a hemacytometer and/or cellometer. Dry weight of different algae cells was also measured to determine the cell counts-to-dry weight correlations. Finally, in vivo measurements of different genus of algae at different cell concentrations and mixed algal group in the presence of humic acid were performed with the LEDIF. A field sample from a local reservoir was measured with the LEDIF and the results were verified using hemacytometer, cellometer, and microscope. The results demonstrated the LEDIF’s capabilities in classifying and quantifying different groups of live algae. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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1198 KiB

Open AccessArticle

Fast Bragg Grating Inscription in PMMA Polymer Optical Fibres: Impact of Thermal Pre-Treatment of Preforms

by Carlos A. F. Marques, Andreas Pospori, Gökhan Demirci, Onur Çetinkaya, Barbara Gawdzik, Paulo Antunes, Ole Bang, Pawel Mergo, Paulo André and David J. Webb

Sensors 2017, 17(4), 891; https://doi.org/10.3390/s17040891 - 18 Apr 2017

Cited by 65 | Viewed by 5432

Abstract

In this work, fibre Bragg gratings (FBGs) were inscribed in two different undoped poly- (methyl methacrylate) (PMMA) polymer optical fibres (POFs) using different types of UV lasers and their inscription times, temperature and strain sensitivities are investigated. The POF Bragg gratings (POFBGs) were [...] Read more.

In this work, fibre Bragg gratings (FBGs) were inscribed in two different undoped poly- (methyl methacrylate) (PMMA) polymer optical fibres (POFs) using different types of UV lasers and their inscription times, temperature and strain sensitivities are investigated. The POF Bragg gratings (POFBGs) were inscribed using two UV lasers: a continuous UV HeCd @325 nm laser and a pulsed UV KrF @248 nm laser. Two PMMA POFs are used in which the primary and secondary preforms (during the two-step drawing process) have a different thermal treatment. The PMMA POFs drawn in which the primary or secondary preform is not specifically pre-treated need longer inscription time than the fibres drawn where both preforms have been pre-annealed at 80 °C for 2 weeks. Using both UV lasers, for the latter fibre much less inscription time is needed compared to another homemade POF. The properties of a POF fabricated with both preforms thermally well annealed are different from those in which just one preform step process is thermally treated, with the first POFs being much less sensitive to thermal treatment. The influence of annealing on the strain and temperature sensitivities of the fibres prior to FBG inscription is also discussed, where it is observed that the fibre produced from a two-step drawing process with well-defined pre-annealing of both preforms did not produce any significant difference in sensitivity. The results indicate the impact of preform thermal pre-treatment before the PMMA POFs drawing, which can be an essential characteristic in the view of developing POF sensors technology. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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2687 KiB

Open AccessArticle

Refractive Index Sensing with D-Shaped Plastic Optical Fibers for Chemical and Biochemical Applications

by Filipa Sequeira, Daniel Duarte, Lúcia Bilro, Alisa Rudnitskaya, Maria Pesavento, Luigi Zeni and Nunzio Cennamo

Sensors 2016, 16(12), 2119; https://doi.org/10.3390/s16122119 - 13 Dec 2016

Cited by 60 | Viewed by 8078

Abstract

We report the optimization of the length of a D-shaped plastic optical fiber (POF) sensor for refractive index (RI) sensing from a numerical and experimental point of view. The sensing principle is based on total internal reflection (TIR). POFs with 1 mm in [...] Read more.

We report the optimization of the length of a D-shaped plastic optical fiber (POF) sensor for refractive index (RI) sensing from a numerical and experimental point of view. The sensing principle is based on total internal reflection (TIR). POFs with 1 mm in diameter were embedded in grooves, realized in planar supports with different lengths, and polished to remove the cladding and part of the core. All D-shaped POF sensors were tested using aqueous medium with different refractive indices (from 1.332 to 1.471) through intensity-based configuration. Results showed two different responses. Considering the refractive index (RI) range (1.33–1.39), the sensitivity and the resolution of the sensor were strongly dependent on the sensing region length. The highest sensitivity (resolution of 6.48 × 10⁻³ refractive index units, RIU) was obtained with 6 cm sensing length. In the RI range (1.41–1.47), the length of the sensing region was not a critical aspect to obtain the best resolution. These results enable the application of this optical platform for chemical and biochemical evanescent field sensing. The sensor production procedure is very simple, fast, and low-cost. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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