1. A short-range quasi-distributed strain and temperature sensing system utilizing a standard telecom laser diodeJure Javornik, Denis Đonlagić, 2025, izvirni znanstveni članek Opis: This article presents a short-range fiber-optic quasi-distributed sensing device suitable for strain and temperature measurement. The sensing assembly consists of an fs laser inscribed reference mirror and a sensing array of equidistantly positioned mirrors. Utilization of the reference mirror and proper sensor geometry selection provides the possibility for a high-resolution spectral interrogation of the sensing array while relying on an ordinary, cost-effective distributed feedback (DFB) telecom laser diode. Beside the telecom DFB diode, the entire interrogation system includes only an additional detector, optical coupler, analog interface and a microcontroller. Measurement resolution better than 1 µε was demonstrated experimentally at a sampling rate exceeding 65 samples per second, while utilizing a sensing device with a typical length of 50 mm and spatial resolution of approximately 2 mm. To demonstrate the application potential of the proposed measuring device, a few different packages and sensor configurations were demonstrated and tested, including a system for tactile sensing applications and a short-range quasi-distributed temperature measurement probe. Ključne besede: optical fiber sensors, short-range quasi-distributed fiber-optic sensor, strain/temperature sensing device, cost-effective interrogation system, tactile sensing, phase subtraction Objavljeno v DKUM: 03.02.2025; Ogledov: 0; Prenosov: 2
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2. The Bray–Liebhafsky oscillatory reaction as a chemosensor for benzenediolsAleksandra Pavičević, Marija Veles, Jelena P. Maksimović, Jelena Tošović, Urban Bren, Uroš Čakar, Maja C. Pagnacco, 2024, izvirni znanstveni članek Ključne besede: oscillatory reactions, Bray–Liebhafsky reaction, benzenediols, chemical sensors, radical scavenging Objavljeno v DKUM: 31.01.2025; Ogledov: 0; Prenosov: 1
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3. Development of biomimetic sensors to determine the functionality of in vitro cell modelsMatjaž Frangež, Noah Emil Glisik, Maša Kaiser, Jaro Vezjak, Matic Žnidaršič, Tanja Zidarič, Tina Maver, 2024, izvirni znanstveni članek Opis: Advances in biomedical science have enabled the development of in vitro models that mimic human tissues. Non-invasive real-time monitoring of these models would provide valuable insights without disrupting the cellular environment. This study explores the use of molecularly imprinted polymers (MIPs) for this purpose, focusing on insulin and lactate as biomarkers of cellular metabolism. MIP sensors were created by electropolymerizing pyrrole around insulin or lactate templates on carbon electrodes. The sensors showed high sensitivity and selectivity, with detection ranges of 20.0–70.0 pM for insulin (LOD: 2.41 pM) and 0.5–3.0 mM for lactate. These findings highlight MIPs’ potential for personalized diagnostics and therapy monitoring. Ključne besede: biomimetic sensors, molecular imprinting, polypyrrole matrix, insulin, MIP sensor Objavljeno v DKUM: 24.01.2025; Ogledov: 0; Prenosov: 3
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4. Potentiometric surfactant sensor with a pt-doped acid-activated multi-walled carbon nanotube-based ionophore nanocompositeNada Glumac, Milan Momčilović, Iztok Kramberger, Darko Štraus, Nikola Sakač, Elvira Kovač-Andrić, Bojan Đurin, Marija Kraševac Sakač, Kristina Đambić, Marija Jozanović, 2024, izvirni znanstveni članek Opis: Two new surfactant sensors were developed by synthesizing Pt-doped acid-activated multiwalled carbon nanotubes (Pt@MWCNTs). Two different ionophores using Pt@MWCNTs, a new plasticizer, and (a) cationic surfactant 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-DHBI (Pt@MWCNT-DHBI ionophore) and (b) anionic surfactant dodecylbenzenesulfonate-DBS (Pt@MWCNT-DBS ionophore) composites were successfully synthesized and characterized. Both surfactant sensors showed a response to anionic surfactants (dodecylsulfate (SDS) and DBS) and cationic surfactants (cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium bromide (CTAB)). The Pt@MWCNT-DBS sensor showed lower sensitivity than expected with the sub-Nernstian response of ≈23 mV/decade of activity for CPC and CTAB and ≈33 mV/decade of activity for SDS and DBS. The Pt@MWCNTDHBI surfactant sensor had superior response properties, including a Nernstian response to SDS (59.1 mV/decade) and a near-Nernstian response to DBS (57.5 mV/decade), with linear response regions for both anionic surfactants down to ≈2 × 10−6 M. The Pt@MWCNT-DHBI was also useful in critical micellar concentration (CMC) detection. Common anions showed very low interferences with the sensor. The sensor was successfully employed for the potentiometric titration of a technical grade cationic surfactant with good recoveries. The content of cationic surfactants was measured in six samples of complex commercial detergents. The Pt@MWCNT-DHBI surfactant sensor showed good agreement with the ISE surfactant sensor and classical two-phase titration and could be used as an analytical tool in quality control Ključne besede: potentiometric surfactant sensor, metal-doped MWCNT, surfactants, carbon nanocomposite, sensors Objavljeno v DKUM: 23.08.2024; Ogledov: 110; Prenosov: 5
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5. Sensor fusion-based approach for the field robot localization on Rovitis 4.0 vineyard robotJurij Rakun, Matteo Pantano, Peter Lepej, Miran Lakota, 2022, izvirni znanstveni članek Opis: This study proposed an approach for robot localization using data from multiple low-cost sensors with two goals in mind, to produce accurate localization data and to keep the computation as simple as possible. The approach used data from wheel odometry, inertial-motion data from the Inertial Motion Unit (IMU), and a location fix from a Real-Time Kinematics Global Positioning System (RTK GPS). Each of the sensors is prone to errors in some situations, resulting in inaccurate localization. The odometry is affected by errors caused by slipping when turning the robot or putting it on slippery ground. The IMU produces drifts due to vibrations, and RTK GPS does not return to an accurate fix in (semi-) occluded areas. None of these sensors is accurate enough to produce a precise reading for a sound localization of the robot in an outdoor environment. To solve this challenge, sensor fusion was implemented on the robot to prevent possible localization errors. It worked by selecting the most accurate readings in a given moment to produce a precise pose estimation. To evaluate the approach, two different tests were performed, one with robot localization from the robot operating system (ROS) repository and the other with the presented Field Robot Localization. The first did not perform well, while the second did and was evaluated by comparing the location and orientation estimate with ground truth, captured by a hovering drone above the testing ground, which revealed an average error of 0.005 m±0.220 m in estimating the position, and 0.6°±3.5° when estimating orientation. The tests proved that the developed field robot localization is accurate and robust enough to be used on a ROVITIS 4.0 vineyard robot. Ključne besede: localization, odometry, IMU, RTK GPS, vineyard, robot, sensors fusion, ROS, precision farming Objavljeno v DKUM: 02.07.2024; Ogledov: 123; Prenosov: 13
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6. Measurements of Small Frequency Differences by Dual Mode 4 MHz Quartz SensorsVojko Matko, 2023, izvirni znanstveni članek Opis: We proposed a method for measuring frequency differences of the order of a few Hz with an experimental error lower than 0.0001% by using two 4 MHz quartz oscillators, the frequencies of which are very close (a few 10 Hz difference) due to the dual mode operation (differential mode with two temperature-compensated signal frequencies or a mode with one signal and one reference frequency). We compared the existing methods for measuring frequency differences with the new method which is based on counting the number of transitions through zero within one beat period of the signal. The measuring procedure requires equal experimental conditions (temperature, pressure, humidity, parasitic impedances etc.) for both quartz oscillators. To ensure equal resonant conditions for oscillation two quartz crystals are needed, which form a temperature pair. The frequencies and resonant conditions of both oscillators must be almost equal, which is achieved by an external inductance or capacitance. In such a way, we minimized all the external effects and ensured highly stable oscillations and high sensitivity of the differential sensors. The counter detects one beat period by an external gate signal former. By using the method of counting transitions through zero within one beat period, we reduced the measuring error by three orders of magnitude, compared to the existing methods. Ključne besede: small frequency difference measurement, temperature-compensated quartz sensors, differential sensors, quartz oscillators, transitions-through-zero method Objavljeno v DKUM: 26.03.2024; Ogledov: 357; Prenosov: 246
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7. The development of an electropolymerized, molecularly imprinted polymer (MIP) sensor for insulin determination using single-drop analysisTanja Zidarič, David Majer, Tina Maver, Matjaž Finšgar, Uroš Maver, 2023, izvirni znanstveni članek Opis: An electrochemical sensor for the detection of insulin in a single drop (50 μL) was developed based on the concept of molecularly imprinted polymers (MIP). The synthetic MIP receptors were assembled on a screen-printed carbon electrode (SPCE) by the electropolymerization of pyrrole (Py) in the presence of insulin (the protein template) using cyclic voltammetry. After electropolymerization, insulin was removed from the formed polypyrrole (Ppy) matrix to create imprinting cavities for the subsequent analysis of the insulin analyte in test samples. The surface characterization, before and after each electrosynthesis step of the MIP sensors, was performed using atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The performance of the developed MIP–SPCE sensor was evaluated using a single drop of solution containing K3Fe(CN)6 and the square-wave voltammetry technique. The MIP–SPCE showed a linear concentration range of 20.0–70.0 pM (R2 = 0.9991), a limit of detection of 1.9 pM, and a limit of quantification of 6.2 pM. The rapid response time to the protein target and the portability of the developed sensor, which is considered a disposable MIP-based system, make this MIP–SPCE sensor a promising candidate for point-of-care applications. In addition, the MIP–SPCE sensor was successfully used to detect insulin in a pharmaceutical sample. The sensor was deemed to be accurate (the average recovery was 108.46%) and precise (the relative standard deviation was 7.23%). Ključne besede: electrochemical sensors, electropolymerisation, electron microscopy Objavljeno v DKUM: 14.03.2024; Ogledov: 335; Prenosov: 42
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8. High-Order Fiber Bragg Grating Corrosion Sensor Based on the Detection of a Local Surface ExpansionVedran 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: 320; Prenosov: 23
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9. An All-Fiber Fabry–Pérot Sensor for Emulsion Concentration MeasurementsSimon 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: 336; Prenosov: 27
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10. Accuracy of Rotational Speed and Torque Sensors for Determining the Mechanical Power of Rotating Electrical MachinesGregor Srpčič, Iztok Brinovar, Bojan Štumberger, Sebastijan Seme, Miralem Hadžiselimović, 2019, objavljeni znanstveni prispevek na konferenci Opis: This paper deals with determining the accuracy of measuring systems for determining the characteristics of rotating electrical machines. Efficiency classes and experimental methods for determining efficiency, are given in a standard, which has to be strictly respected. For determining the efficiency of an electrical machine, it is necessary to have a modern and accurate measurement system with sensors of high accuracy classes, which enables the user to carry out precise measurements and consequently, to determine all the characteristics of the electrical machine. This paper will be focused on torque and speed measurements. Ključne besede: efficiency, measuring system, electric machines, torque and rotational sensors, accuracy Objavljeno v DKUM: 04.12.2023; Ogledov: 529; Prenosov: 30
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