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High-Order Fiber Bragg Grating Corrosion Sensor Based on the Detection of a Local Surface Expansion
Vedran Budinski, Matej Njegovec, Simon Pevec, Boris Macuh, Denis Đonlagić, 2023, izvirni znanstveni članek

Opis: This paper presents a fiber optic sensor for the detection of corrosion processes that occur on metal surfaces. In the proposed sensor design, a sensing fiber with an inscribed high-order Bragg grating is attached to the observed metal surface. A broadening of high-order Bragg grating spectral characteristics is observed and used to detect small and highly localized longitudinal strain variations that occur along the fiber as a result of corrosive rust flakes' formations beneath the sensing fiber. The proposed approach provides a straightforward fabrication method, the possibility for unobtrusive mounting, including mounting of the sensor beneath the corrosion-protective layers, and consistent corrosion detection yields.
Ključne besede: optical fiber sensors, corrosion, impact of corrosion, optic sensors
Objavljeno v DKUM: 09.02.2024; Ogledov: 74; Prenosov: 8
.pdf Celotno besedilo (1,58 MB)
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An All-Fiber Fabry–Pérot Sensor for Emulsion Concentration Measurements
Simon Pevec, Janez Kunaver, Vedran Budinski, Matej Njegovec, Denis Đonlagić, 2023, izvirni znanstveni članek

Opis: This paper describes a Fabry-Perot sensor-based measuring system for measuring fluid composition in demanding industrial applications. The design of the sensor is based on a two-parametric sensor, which enables the simultaneous measurement of temperature and refractive index (RI). The system was tested under real industrial conditions, and enables temperature-compensated online measurement of emulsion concentration with a high resolution of 0.03 Brix. The measuring system was equipped with filtering of the emulsion and automatic cleaning of the sensor, which proved to be essential for successful implementation of a fiber optic RI sensor in machining emulsion monitoring applications.
Ključne besede: optical fiber sensors, Fabry–Pérot interferometer, refractive index, temperature, emulsion concentration
Objavljeno v DKUM: 06.02.2024; Ogledov: 62; Prenosov: 3
.pdf Celotno besedilo (4,44 MB)
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Signal processor for optical fiber sensors based on MEMS Fabry-Perot interferometer : master's thesis
Nikola Uremović, 2020, magistrsko delo

Opis: In the master thesis, we have created an interrogation system for measuring the change of the optical path in the Fabry-Perot interferometer caused by the strain of the surface at which it was attached to. The change of strain can be calculated via a change in optical path length which is visible as a shift in phase angle. The system will be used as a system for measuring strain, although it can be used for measuring various physical parameters that can cause a change in optical path length, such as pressure, force, temperature, etc. Initially, the theoretical background of the system and project components are represented and explained, following the building process of the electronic and optical part of the project. Lastly, the working principle and programming algorithms of a system are presented and explained. Measurement results are shown at the end, as well as the conclusion that is drawn from the thesis.
Ključne besede: optical fibers, sensors, interferometer, signal processing
Objavljeno v DKUM: 04.11.2020; Ogledov: 935; Prenosov: 106
.pdf Celotno besedilo (5,11 MB)

Monitoring the evaporation of fluids from fiber-optic micro-cell cavities
Eyal Preter, Borut Preložnik, Vlada Artel, Chaim Sukenik, Denis Đonlagić, Avi Zadok, 2013, izvirni znanstveni članek

Opis: Fiber-optic sensors provide remote access, are readily embedded within structures, and can operate in harsh environments. Nevertheless, fiber-optic sensing of liquids has been largely restricted to measurements of refractive index and absorption spectroscopy. The temporal dynamics of fluid evaporation have potential applications in monitoring the quality of water, identificationof fuel dilutions, mobile point-of-care diagnostics, climatography and more. In this work, the fiber-optic monitoring of fluids evaporation is proposed and demonstrated. Sub-nano-liter volumes of a liquid are applied to inline fiber-optic micro-cavities. As the liquid evaporates, light is refracted out of the cavity at the receding index boundary between the fluid and the ambient surroundings. A sharp transient attenuation in the transmission of light through the cavity, by as much as 50 dB and on a sub-second time scale, is observed. Numerical models for the transmission dynamics in terms of ray-tracing and wavefront propagation are provided. Experiments show that the temporal transmission profile can distinguish between different liquids.
Ključne besede: fiber-optic sensors, opto-fluidics, evaporation monitoring, optical micro-cells, fiber cavities, droplet analysis
Objavljeno v DKUM: 22.06.2017; Ogledov: 1069; Prenosov: 324
.pdf Celotno besedilo (551,58 KB)
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Fiber-optic sensors for measurements of torsion, twist and rotation : a review
Vedran Budinski, Denis Đonlagić, 2017, pregledni znanstveni članek

Opis: Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.
Ključne besede: fiber optic sensors, twist sensors, rotation sensors, circular birefringence, linear birefringence, FBG, polarization, optical fibers, Fiber Bragg Gratings
Objavljeno v DKUM: 22.06.2017; Ogledov: 1416; Prenosov: 374
.pdf Celotno besedilo (8,96 MB)
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Spin-coating for optical-oxigen-sensor preparation
Polonca Brglez, Andrej Holobar, Aleksandra Pivec, Mitja Kolar, 2014, izvirni znanstveni članek

Opis: Thin-film oxygen sensors were prepared using the spin-coating technique, where a tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex (RuDPP) in various solvents and silicones deposited on different substrates was used for the sensor production. By changing the spin-coating set-up parameters, homogeneous sensor coatings and the optimum sensor response to oxygen were studied – the sensors were exposed to various concentrations of oxygen within the range from 0% to 100 %. During the presented study, the optimum results were obtained when a 150 µL of sensor solution was applied to a Dataline foil using silicone E4 and a chloroform solvent. A spin coater with the following three rotation stages was used: 750/700 r/min for 3 s, 300 r/min for 3 s and 150 r/min for 4 s. The spin-coating technique has several benefits: it is fast, easy to use and appropriate for low-volume operations. It allows modifications and preparations of several sensor series using the minimum reagent consumption. However, the disadvantage of this technique also has to be mentioned, namely, an uneven film thickness in the radial direction. The film thickness mainly depends on the experimental set-up (volume, rotation time and speed, solvent viscosity and evaporation). Spin coating as an alternative and very flexible technique for an oxygen-sensor preparation is suggested for the laboratory-scale work, where the majority of experimental data could be used when other new coating methods are also researched and implemented.
Ključne besede: optical sensors, spin coating, oxigen
Objavljeno v DKUM: 21.12.2015; Ogledov: 1632; Prenosov: 99
.pdf Celotno besedilo (254,63 KB)
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Characterisation of an optical sensor membrane based on the metal ion indication Pyrocatechol Violet
Ivana Murković Steinberg, Aleksandra Lobnik, Otto S. Wolfbeis, 2003, izvirni znanstveni članek

Opis: A non-specific photometric metal ion indicator Pyrocatechol Violet (PV) was tested for its potential use in a metal-sensitive optrode membrane. The water soluble indicator was lipophilised in the form of an ion pair with tetraoctylammonium cation (TOA), and subsequently immobilised in a plasticised PVC membrane. The spectral response of the membrane in the presence of various transition metal ions was studied. It was found that the ability of PV to form complexes with metal ions significantly reduced following immobilisation, with the exception of Cu(II). A number of factors responsible for the improved selectivity and high sensitivity of immobilised PV towards Cu(II) were identified. Amongst those, the most important is the presence of quaternary ammonium salt in the membrane which induced a significant bathochromic shift of the PV-Cu(II) chelate absorption maximum, as well as the intensification of the chelate absorption band. The membrane responds to Cu(II) irreversibly by changing colour from yellow to green (absorption maximum at 740 nm), and typically, an exposure time of 10 min enables the determination of Cu(II) in the 1-100 M range. A comparison of selectivity and sensitivity characteristics between the water soluble form of the indicator and the immobilised form was performed, and the effects of pH and lipophilic surfactant additives on the response mechanism are discussed.
Ključne besede: optical sensors, sensor membrane, PVC membrane, photometric metal ion indicators, metal-sensitive optrode membrane, lipophilic ion pairs
Objavljeno v DKUM: 01.06.2012; Ogledov: 1913; Prenosov: 31
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Sol-gel-based optical sensor for the detection of aqueous amines
Špela Korent Urek, Aleksandra Lobnik, Gerhard J. Mohr, 2007, izvirni znanstveni članek

Opis: We present an optical sensor for the detection of aqueous amines obtained by incorporating chromoionophore XV (ETHT 4001) into sol-gel thin films. Acid- and base-catalyzed sol-gel processes were studied to prepare stable ormosil layers using various amounts of organically modified sol-gel precursor such asmethyltriethoxysilane (MTriEOS). The sensor layers were coated with a protective layer of microporous white polytetrafluoroethylene (PTFE) in order to prevent interference from ions and ambient light. The measurements were carried out in a flow-through cell in the reflection mode. Acid-catalyzed ormosil layers (pH 1) based on the copolymerization of tetraethoxysilane (TEOS) and MTriEOS did not show any change in signal upon exposure to aqueous amine solutions, while base-catalyzed sensor layers (pH 3 and 13) showed significant changes in signal. The response time (t100) for the base-catalyzedsensor layer L3 (pH 13) upon exposure to different solutions containing 0-608 mmol L-1 aqueous propylamine was 20-30 s, the regeneration time was 70 s and the detection limit was 0.1 mmol L-1. The sensor response was reproducible and reversible. The porous ormosil layers permit dry sensor storage conditions.
Ključne besede: analytical chemistry, optical sensors, sol-gel technology, determination of amines, fluorimetry
Objavljeno v DKUM: 01.06.2012; Ogledov: 3068; Prenosov: 90
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Optical chemical sensors : design and applications
Aleksandra Lobnik, Matejka Turel, Špela Korent Urek, 2012, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Ključne besede: optical chemical sensors, opt(r)odes, chemical sensors
Objavljeno v DKUM: 01.06.2012; Ogledov: 2373; Prenosov: 101
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