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Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: 31 July 2025 | Viewed by 11579

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Special Issue Editors

Prof. Dr. Michele Norgia

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Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Via Ponzio 34/5, 20133 Milano, Italy
Interests: optical sensors; interferometry; optoelectronics; optical measurements
Special Issues, Collections and Topics in MDPI journals

Dr. Elfed Lewis

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Guest Editor

Optical Fibre Sensors Research Centre (OFSRC), University of Limerick, Limerick V94 T9PX, Ireland
Interests: optical fibre sensors; medical sensors; optical fibre instrumentation
Special Issues, Collections and Topics in MDPI journals

Dr. Alberto Vallan

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Guest Editor

Politecnico di Torino, Department of Electronics and Telecommunications, corso Duca degli Abruzzi, 24, I-10129 Torino, Italy
Interests: measurement instruments; sensors; optical fiber sensors; plastic optical fibers
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Optical sensors have evolved to be one of the most studied and widely applied sensing techniques in industrial, engineering, medical, and biological applications.

This Special Issue, entitled "Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology", focuses on collecting and discussing novel and advanced research works in various fields of optical measurements and sensors.

It pursues recent developments and new applications of optical sensing, including significant improvements in sensitivity, precision, accuracy, measurement speed, miniaturization of systems, and integration to optimize systems. Moreover, innovative designs of optical sensors for novel and specific applications are sought to increase the value of the discussion. Submissions including original research papers as well as review articles that summarize recent technical developments are welcome.

Topics of interest include, but are not limited to, the following:

General photonic sensors and measurement techniques;
Interferometric sensors;
Optical rangefinder;
Micro–opto–electro-mechanical systems (MOEMSs);
Novel optical sensing technologies;
Laser doppler velocimetry;
Optical fiber sensors;
Single-point, multi-point, and distributed measurements.

We expect many colleagues in the field of optical sensors and measurements to contribute to this Special Issue.

Prof. Dr. Michele Norgia
Prof. Dr. Elfed Lewis
Dr. Alberto Vallan
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

optical sensors
interferometry
fiber optical sensors
optical measurements
laser doppler velocimetry
optical rangefinder

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Published Papers (7 papers)

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Research

16 pages, 2617 KiB

Open AccessArticle

Integrated Spectral Sensitivity as Physics-Based Figure of Merit for Spectral Transducers in Optical Sensing

by Felix L. McCluskey, Anne van Klinken and Andrea Fiore

Sensors 2025, 25(2), 440; https://doi.org/10.3390/s25020440 - 13 Jan 2025

Viewed by 715

Abstract

The design of optical sensors aims at providing, among other things, the highest precision in the determination of the target measurand. Many sensor systems rely on a spectral transducer to map changes in the measurand into spectral shifts of a resonance peak in the reflection or transmission spectrum, which is measured by a readout device (e.g., a spectrometer). For these spectral transducers, figures of merit have been defined which are based on specific assumptions on the readout and the data analysis. In reality, however, different transducers achieve optimal performance with different types of readout. Additionally, some transducers present a more complex spectral response for which existing figures of merit do not apply. In this paper, we investigate an approach to quantifying the potential performance of a given transducer for a more general class of readout methods. Starting from the Cramér–Rao lower bound, we define a new figure of merit, the integrated spectral sensitivity, which is directly related to the physical limit of precision and applicable to a wide variety of sensing systems. We apply this analysis to two different examples of transducers. The results bring useful insights into the design of optical sensors. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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13 pages, 3496 KiB

Open AccessArticle

Label- and Reagent-Free Optical Sensor for Absorption-Based Detection of Urea Concentration in Water Solutions

by Carlo Anelli, Vanessa Pellicorio, Valentina Bello and Sabina Merlo

Sensors 2024, 24(9), 2754; https://doi.org/10.3390/s24092754 - 26 Apr 2024

Cited by 1 | Viewed by 1616

Abstract

Contactless and label-free detection of urea content in aqueous solutions is of great interest in chemical, biomedical, industrial, and automotive applications. In this work, we demonstrate a compact and low-cost instrumental configuration for label-free, reagent-free, and contactless detection of urea dissolved in water, which exploits the absorption properties of urea in the near-infrared wavelength region. The intensity of the radiation transmitted through the fluid under test, contained in a rectangle hollow glass tubing with an optical pathlength of 1 mm, is detected in two spectral bands. Two low-cost, low-power LEDs with emission spectra centered at λ = 1450 nm and λ = 2350 nm are used as readout sources. The photodetector is positioned on the other side of the tubing, in front of the LEDs. The detection performances of a photodiode and of a thermal optical power detector have been compared, exploiting different approaches for LED driving current modulation and photodetected signal processing. The implemented detection system has been tested on urea–water solutions with urea concentrations from 0 up to 525 mg/mL as well as on two samples of commercial diesel exhaust fluid (“AdBlue™”). Considering the transmitted intensity in presence of the urea–water solution, at λ = 1450 nm and λ = 2350 nm, normalized to the transmitted intensity in presence of water, we demonstrate that their ratio is linearly related to urea concentration on a wide range and with good sensitivity. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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27 pages, 9834 KiB

Open AccessArticle

Detection and Recognition of Voice Commands by a Distributed Acoustic Sensor Based on Phase-Sensitive OTDR in the Smart Home Concept

by Tatyana V. Gritsenko, Maria V. Orlova, Andrey A. Zhirnov, Yuri A. Konstantinov, Artem T. Turov, Fedor L. Barkov, Roman I. Khan, Kirill I. Koshelev, Cesare Svelto and Alexey B. Pnev

Sensors 2024, 24(7), 2281; https://doi.org/10.3390/s24072281 - 3 Apr 2024

Cited by 2 | Viewed by 1864

Abstract

In recent years, attention to the realization of a distributed fiber-optic microphone for the detection and recognition of the human voice has increased, whereby the most popular schemes are based on φ-OTDR. Many issues related to the selection of optimal system parameters and the recognition of registered signals, however, are still unresolved. In this research, we conducted theoretical studies of these issues based on the φ-OTDR mathematical model and verified them with experiments. We designed an algorithm for fiber sensor signal processing, applied a testing kit, and designed a method for the quantitative evaluation of our obtained results. We also proposed a new setup model for lab tests of φ-OTDR single coordinate sensors, which allows for the quick variation of their parameters. As a result, it was possible to define requirements for the best quality of speech recognition; estimation using the percentage of recognized words yielded a value of 96.3%, and estimation with Levenshtein distance provided a value of 15. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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16 pages, 2895 KiB

Open AccessArticle

Dynamic Measurement of a Cancer Biomarker: Towards In Situ Application of a Fiber-Optic Ball Resonator Biosensor in CD44 Protein Detection

by Zhuldyz Myrkhiyeva, Kanagat Kantoreyeva, Aliya Bekmurzayeva, Anthony W. Gomez, Zhannat Ashikbayeva, Meruyert Tilegen, Tri T. Pham and Daniele Tosi

Sensors 2024, 24(6), 1991; https://doi.org/10.3390/s24061991 - 21 Mar 2024

Cited by 4 | Viewed by 1973

Abstract

The accuracy and efficacy of medical treatment would be greatly improved by the continuous and real-time monitoring of protein biomarkers. Identification of cancer biomarkers in patients with solid malignant tumors is receiving increasing attention. Existing techniques for detecting cancer proteins, such as the enzyme-linked immunosorbent assay, require a lot of work, are not multiplexed, and only allow for single-time point observations. In order to get one step closer to clinical usage, a dynamic platform for biosensing the cancer biomarker CD44 using a single-mode optical fiber-based ball resonator biosensor was designed, constructed and evaluated in this work. The main novelty of the work is an in-depth study of the capability of an in-house fabricated optical fiber biosensor for in situ detection of a cancer biomarker (CD44 protein) by conducting several types of experiments. The main results of the work are as follows: (1) Calibration of the fabricated fiber-optic ball resonator sensors in both static and dynamic conditions showed similar sensitivity to the refractive index change demonstrating its usefulness as a biosensing platform for dynamic measurements; (2) The fabricated sensors were shown to be insensitive to pressure changes further confirming their utility as an in situ sensor; (3) The sensor’s packaging and placement were optimized to create a better environment for the fabricated ball resonator’s performance in blood-mimicking environment; (4) Incubating increasing protein concentrations with antibody-functionalized sensor resulted in nearly instantaneous signal change indicating a femtomolar detection limit in a dynamic range from 7.1 aM to 16.7 nM; (5) The consistency of the obtained signal change was confirmed by repeatability studies; (6) Specificity experiments conducted under dynamic conditions demonstrated that the biosensors are highly selective to the targeted protein; (7) Surface morphology studies by AFM measurements further confirm the biosensor’s exceptional sensitivity by revealing a considerable shift in height but no change in surface roughness after detection. The biosensor’s ability to analyze clinically relevant proteins in real time with high sensitivity offers an advancement in the detection and monitoring of malignant tumors, hence improving patient diagnosis and health status surveillance. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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15 pages, 4605 KiB

Open AccessArticle

Diagnostics of Internal Defects in Composite Overhead Insulators Using an Optic E-Field Sensor

by Damiano Fasani, Luca Barbieri, Andrea Villa, Daniele Palladini, Roberto Malgesini, Giovanni D’Avanzo, Giacomo Buccella and Paolo Gadia

Sensors 2024, 24(5), 1359; https://doi.org/10.3390/s24051359 - 20 Feb 2024

Viewed by 1523

Abstract

Composite insulators for high-voltage overhead lines have better performances and are lighter than traditional designs, especially in heavily polluted areas. However, since it is a relatively recent technology, reliable methods to perform live-line diagnostics are still under development, especially with regard to internal defects, which provide few external symptoms. Thermal cameras can be employed, but their use is not always straightforward as the sun radiation can hide the thermal footprint of internal degenerative effects. In this work, an optical E-field sensor has been used to diagnose the internal defects of a set of composite insulators (bandwidth 200 mHz–50 MHz, min. detectable E-field 100 V/m). Moreover, a modelling activity using finite elements has been carried out to identify the possible nature of the defects by comparing experimental E-field profiles with those simulated assuming a specific defect geometry. The results show that the sensor can detect the presence of an internal defect, since its presence distorts the E-field profile when compared to the profile of a sound insulator. Moreover, the measured E-field profiles are compatible with the corresponding simulated ones when a conductive defect is considered. However, it was observed that a defect whose conductivity is not at least two orders of magnitude greater than the conductivity of the surroundings remains undetected. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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12 pages, 2721 KiB

Open AccessArticle

Experimental Characterization of Polarized Light Backscattering in Fog Environments

by Maria Ballesta-Garcia, Sara Peña-Gutiérrez, Pablo García-Gómez and Santiago Royo

Sensors 2023, 23(21), 8896; https://doi.org/10.3390/s23218896 - 1 Nov 2023

Cited by 2 | Viewed by 1625

Abstract

This paper focuses on the experimental characterization of the polarization behavior of light backscattered through fog. A polarimetric orthogonal state contrast imager and an active, purely polarized white illuminator system are used to evaluate both linear and circular polarization signals. The experiments are carried out in a macro-scale fog chamber under controlled artificial fog conditions. We explore the effect of backscattering in each imaging channel, and the persistence of both polarization signals as a function of meteorological visibility. We confirm the presence of the polarization memory effect with circularly polarized light, and, as a consequence, the maintenance of helicity in backscattering. Moreover, the circular cross-polarized channel is found to be the imaging channel less affected by fog backscattering. These results are useful and should be taken into account when considering active polarimetric imaging techniques for outdoor applications under foggy conditions. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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14 pages, 4613 KiB

Open AccessArticle

Influence of Tilting Angle on Temperature Measurements of Different Object Sizes Using Fiber-Optic Pyrometers

by Salvador Vargas, Alberto Tapetado and Carmen Vázquez

Sensors 2023, 23(19), 8119; https://doi.org/10.3390/s23198119 - 27 Sep 2023

Cited by 1 | Viewed by 1330

Abstract

This article presents a new model of optical power gathered by a fiber-optic pyrometer when there is a tilting angle between the fiber longitudinal axis and the vector perpendicular to the tangent plane of the emitted surface. This optical power depends on the fiber specifications, such as the diameter and the numerical aperture (NA), as well as the object parameters, including its diameter, emissivity, and tilting angle. Some simulations are carried out using other pyrometers from the literature without tilting to validate the model. Additional simulations with different optical fibers, object sizes, and distances at different tilting angles allow us to describe the behavior of the pyrometer when the object is smaller than the optical fiber field of view (the light cone defined by its NA). The results show that for a finite surface object, the power collected by the optical fiber is affected by changes in the tilting angle, greater tilting lesser gathered power, and reaching the maximum power when the field of view of the fiber covers up the entire object, as expected. On the other hand, additional equations are presented to describe the maximum tilting angle, and distance that allow the maximum power gathered for a determined object diameter and fiber, avoiding temperature measurement errors. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Optical Measurements and Sensing Technology)

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