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U-shaped plastic optical fiber functionalized with metal oxides thin film for H2S gas sensor applications
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... Because dissolved CO 2 can reduce the solution pH, CO 2 sensors also employ pH indicators (colorimetric or fluorescent dyes) within various sensing layers such as silica gel coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H 2 S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO 2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. More H 2 S sensitive materials can be found in References [189,190]. ...
... coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H2S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. More H2S sensitive materials can be found in References [189,190]. ...
... Al [191] 0.05 mol/L NaOH uW increase in light transmission in 5 min coating, polymer matrix with quantum dots, and sol-gel matrix with silica nanoparticles [172][173][174][175][176][177]. H2S monitoring often utilizes reactive sensing materials such as Ag [178,179], Cu [180,181], ZnO [182,183], CuO doped SnO2 [184], CdO [185], and fluorescent or luminescent indicators [186][187][188]. More H2S sensitive materials can be found in References [189,190]. ...
Corrosion has been a great concern in the oil and natural gas industry costing billions of dollars annually in the U.S. The ability to monitor corrosion online before structural integrity is compromised can have a significant impact on preventing catastrophic events resulting from corrosion. This article critically reviews conventional corrosion sensors and emerging sensor technologies in terms of sensing principles, sensor designs, advantages, and limitations. Conventional corrosion sensors encompass corrosion coupons, electrical resistance probes, electrochemical sensors, ultrasonic testing sensors, magnetic flux leakage sensors, electromagnetic sensors, and in-line inspection tools. Emerging sensor technologies highlight optical fiber sensors (point, quasi-distributed, distributed) and passive wireless sensors such as passive radio-frequency identification sensors and surface acoustic wave sensors. Emerging sensors show great potential in continuous real-time in-situ monitoring of oil and natural gas infrastructure. Distributed chemical sensing is emphasized based on recent studies as a promising method to detect early corrosion onset and monitor corrosive environments for corrosion mitigation management. Additionally, challenges are discussed including durability and stability in extreme and harsh conditions such as high temperature high pressure in subsurface wellbores.
... The sensing region of the fiber was then carefully dry heated to introduce a bend. The sensing region was gradually bent at temperatures ranging from 90 • to 100 • C [52], [54], [55]. The varied bending temperatures are due to the fact that different fiber optic materials have different melting points (M.P), and care must be taken to ensure that the temperature does not exceed M.P. therefore, a heat radiating rod was introduced towards the center of the 1 cm sensing zone to bend the fiber into a U-shape, as shown in Fig. 1. ...
This work presents an evanescent wave-based U-shaped plastic optical fiber sensor. The effect of bend-induced material deformation on numerical aperture (N.A) and V-number has been thoroughly investigated. With sufficiently smaller bend radius, the numerical aperture of a U-bent fiber decreases toward zero near the inner curvature of the bending. The present scenario causes entire optical power loss at interface between core-clad (sample region) interfaces, resulting in no detectable power. It has been observed that as the bending radius increases, the local N.A value decreases while the refractive index of the surrounding region remains fixed. As a result, the fractional power in the surrounding region rises, resulting in increased absorbance and sensitivity of the EW absorption-based optical fiber sensor.
... The sensing region of the fiber was then carefully dry heated to introduce a bend. The sensing region was gradually bent at temperatures ranging from 90 • to 100 • C [52], [54], [55]. The varied bending temperatures are due to the fact that different fiber optic materials have different melting points (M.P), and care must be taken to ensure that the temperature does not exceed M.P. therefore, a heat radiating rod was introduced towards the center of the 1 cm sensing zone to bend the fiber into a U-shape, as shown in Fig. 1. ...
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%.
... For PCS, the temperature in the range of 400 o C to 500 o C and 700 o C were used for fiber core diameter of 200 μm and 600 μm, respectively [35,46,47]. Meanwhile, for POF, the heating temperature applied on 1 mm plastic fiber was 70 o C [71], 80 o C [72] and 100 o C [53]. ...
A wide range of geometrical deformations of fiber optic sensors (FOSs) have been explored to improve their performance. In particular, fiber optics bent into a U-shape present various advantages over other approaches and considerably improved performance in terms of sensitivity. The improvement in sensitivity can be understood as a result of the enhanced penetration depth of the evanescent field and higher evanescent power in the cladding or surrounding medium. Consequently, a larger portion of the propagating light experiences changes due to variations in the local refractive index (RI). In view of their significant benefits, U-shaped FOSs deserve a thorough investigation. This review outlines the theoretical model and design considerations along with the fabrication process of U-shaped FOSs. In addition, this paper aims to provide researchers with guidelines on the factors to consider in designing and optimizing U-shaped FOSs.
Plasmonic fiber optic sensors have garnered immense interest in the past two decades owing to their inherent structural, functional, and operational benefits. In particular, U-bent fiber optic sensors with their high evanescent wave absorbance sensitivity offer a unique advantage of efficient monitoring of the optical extinction properties of the plasmonic nanoparticles for the development of a variety of sensing applications. This chapter describes the fundamentals of sensing in the LSPR-based U-bent fiber optic probes. Various factors affecting the performance of plasmonic U-bent probes such as nanoparticle size, shape, geometrical design, and other fiber parameters are discussed in detail. In addition, this chapter provides in-depth coverage of various sensing strategies developed for U-bent plasmonic fiber optic sensor and their applications towards a variety of chemicals and biosensors. Although these plasmonic sensors could achieve the detection limit down to the attomolar levels of the analyte, concerted efforts are needed towards the translation and commercialization of U-bent plasmonic fiber optic sensors to devise a low-cost, field-deployable, point-of-care diagnostic system.
A Plastic Optical Fiber (POF) in U-shape, functionalized with a thin film of copper oxide, was developed as a hydrogen sulfide gas sensor. Unlike resistive-type Semiconductor Metal Oxide (SMOX) gas sensors, the present optical sensing probe is neither electrically charged nor demands a heating system as it functions at room temperature (25 ◦C). Pulsed Laser Deposition (PLD) method was used to coat optical fibers with copper, nickel and tin oxides. However, only CuO-functionalized fibers demonstrated a detectable signal to the H2S exposure. The PLD copper oxide thin films were composed of a dominantly amorphous structure and embedded Cu2-xO crystallites. Fourier Transform Infrared Spectroscopy (FTIR) demonstrated that the PLD process created nega-tively charged oxygen species adsorbed on the surface of the Cu2-xO, which react with H2S are responsible for the sensing mechanism. A state-of-the-art modification in the fiber’s geometry, with more curves, was presented and improved the Signal to Noise Ratio (SNR). The sensor demonstrated a response time as low as 1 min during an exposure to 200 ppm H2S and a minimum detectable H2S concentration, CH2S, around 10 ppm. The experimental data led to an interpolation that estimates a logarithmic relationship between the saturated signal and CH2S. The sensor demonstrates a remarkable selectivity to H2S. Furthermore, the saturated signal represents an inverse relation with the Relative Humidity (RH).
Due to its multifunctional character, nanocellulose (NC) is one of the most interesting nature-based nanomaterials and is attracting attention in a myriad of fields such as biomaterials, engineering, biomedicine, opto/electronic devices, nanocomposites, textiles, cosmetics and food products. Moreover, NC offers a plethora of outstanding properties, including inherent renewability, biodegradability, commercial availability, flexibility, printability, low density, high porosity, optical transparency as well as extraordinary mechanical, thermal and physicochemical properties. Consequently, NC holds unprecedented capabilities which are appealing to the scientific, technologic and industrial community. In this review, we highlight how NC is being tailored and applied in (bio)sensing technology, whose results aim at displaying analytical information related to various fields such as clinical/medical diagnostics, environmental monitoring, food safety, physical/mechanical sensing, labeling and bioimaging applications. In fact, NC-based platforms could be considered an emerging technology to fabricate efficient, simple, cost-effective and disposable optical/electrical analytical devices for several (bio)sensing applications including health care, diagnostics, environmental monitoring, food quality control, forensic analysis and physical sensing. We foresee that many of the (bio)sensors which are currently based on plastic, glass or conventional paper platforms will be soon transferred to NC and this generation of (bio)sensing platforms could revolutionize the conventional sensing technology.
Natural fibres are a good reinforcing material. Among the various natural fibres, sisal fibre is of particular interest, since its composites have high impact strength besides having moderate tensile and flexural properties compared to other lignocellulosic fibres. Sisal fibre is a promising reinforcement for use in composites on account of its low cost, low density, high specific strength and modulus, no health hazards, easy availability in some countries and renewability. The present work focused on the recent developments in the field of sisal fibre reinforced phenol formaldehyde composites with reference to the properties of sisal fibre, processing techniques, and the physical and mechanical properties of the composites. The mechanical properties of the composites show much improvement by the addition of sisal fibre of optimum fibre length 40 mm and fibre loading 54 wt%. The better fibre matrix interaction is shown by sisal-PF containing 54 wt%. The comparison with other natural fibres shows that sisal fibre is a good reinforcing agent in PF matrix. Flexural strength and impact strength of the composites were examined and are increased with increasing the fibre content. Ageing studies of the composites showed a similar trend to that of un-aged samples. Interestingly, water absorption test results show that composite with 54 wt% fibre loading have good interaction with the matrix and contains less voids.
Smart and novel materials require the replacement of conventional composites with superior ones, which requires an advanced class of composites with multi-functionality. Multi-scale composites are advanced composites that are reinforced with nanoscale materials along with macroscale fibers, and these materials have attracted the attention of researchers as well as various industries. Multi-scale composites have potential applications in almost every field due to their remarkable features like extraordinary mechanical, electrical, and optical properties; extremely high aspect ratios of the nanomaterial constituents; and the uniformity, flexibility, and stability of the fibers. To optimize the performance of these kinds of composites, it is crucial to understand the selection of appropriate reinforcements, processing, and utilization of these advanced materials. Most reviews in this area concentrate only on CNTs, while this review considers other nanomaterials too. Additionally, various methods to improve the dispersion of nanomaterials into the matrix are also discussed. Overall, this article focuses on the components of multi-scale composites, key challenges related to their processing, and the multi-functionality of designed multi-scale composites.
Starch based films, reinforced by two types of polysaccharide-based crystals, were prepared and compared. The films were transparent and their surface was smooth in appearance. Addition of crystals increased the Young's modulus and tensile strength of starch-based materials and decreased elongation at break. Scanning electron microscopic observation indicated good compatibility between starch matrix and the reinforcing fillers due to same chemical unit (glucose). Cellulose crystals have higher thermal stability than that of starch crystals; this provides better processibility and superior mechanical properties to starch films filled with cellulose crystals. On the other hand, starch films filled with starch crystals demonstrated higher protection againstUV radiation. Since all the components used in this work belong to food sources, the prepared films are biodegradable, safe for food packaging and can also be used to developed ible films (such as wrappers for candies) and medicinal capsules (both soft and hard capsules).
Eco-friendly “green” nano composites were fabricated from potato starch and cellulose nanofibers from pineapple leaf. Nanocomposites of starch/cellulose nanofibers were prepared by solution mixing followed by casting. The investigation of the viscoelastic properties confirms starch macromolecular chain confinement around the nano scale cellulose surface, superior dispersion and very good interaction between thermoplastic starch and cellulose nanofibers. The degree of chain confinement was quantified. The chain confinement was associated with the immobilization of the starch macromolecular chains in the network formed by the nano-scale cellulose fibers as a result of hydrogen boding interactions. From the results, it was assumed that the starch glycerol system exhibits a heterogenous nature and cellulose nanofibers tend to move towards glycerol rich starch phase. Barrier properties also improved with the addition of nanofiller up to 3 wt.% but further addition depreciated properties due to possible fiber agglomeration. The kinetics of diffusion was investigated and typical kinetic parameters were determined and found that the nanocomposites follow pseudo fickian behaviour. The outcome of the work confirms that the prepared nanocomposites films can be used as a swap for packaging applications.
The increasing awareness of the environment has raised so much concerns in the way we live and the manner to which we dispose our waste. The rapid growth in polymer production has resulted in increasing concerns about the consumption of nonrenewable resources and the environmental impacts associated with its production and disposal. Polymer waste is one of the major components in municipal solid waste and is increasingly becoming a huge burden in industrialized nations. The rise in the use of plastic, coupled with increasing concerns about its disposal, has led to a renewed interest in its recycling and recovery. The technologies involved in the recovery and recycling of polymers are rapidly growing, however, there is no specific pattern of treating polymer waste. The technology depends on the type of material used in the production and consumption pattern. This chapter, therefore, discusses the patterns of polymer consumption, the environmental concerns, and different modes of recycling polymer waste.
A review for optical fiber hydrogen sensors based on palladium (Pd) and tungsten oxide (WO3) thin films is presented, with specific focus on the measurement methods, probe structures, and sensing properties of different sensors. Firstly, the theoretical models behind the optical fiber hydrogen sensors, as well as their practical limitations, are addressed. Secondly, four mainstream measurement methods, including intensity, fiber Bragg grating (FBG), interferometer, surface plasmon resonance (SPR), which have been proposed to sense the physicochemical properties variations of sensitive thin films when exposed to hydrogen, are reviewed. Then, the advantages and disadvantages of all the above measurement methods are also discussed and compared. Finally, the existing problems and future prospects of optical fiber hydrogen sensors are pointed out.
