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Special Issue "Selected Papers from the 5th International Conference on Applications of Optics and Photonics (AOP2022)"

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

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 3325

Special Issue Editors

Prof. Dr. Orlando Frazão
E-Mail Website
Guest Editor
INESC-Tec, University of Porto, Porto, Portugal
Interests: optical sensors
Prof. Dr. Rogerio Nogueira
E-Mail Website
Guest Editor
Instituto de Telecomunicações, University of Aveiro, Aveiro, Portugal
Interests: optical communications and sensors

Special Issue Information

Dear Colleagues,

The 5th International Conference on Applications of Optics and Photonics (AOP2021) will be held in Guimarães (Portugal), 19–23 July 2021. Since its first edition back in 2011, the AOP conference has provided an excellent opportunity to foster, in an open and friendly environment, the establishment of the widest range of cooperation projects and relationships with colleagues and institutions involved in optics and photonics research from all around the world. With this conference, open to contributions in all domains of optics and photonics and application fields, we expect to review the state of the art in these subjects and to foresee and discuss the future of research in optics and photonics. A large number of plenary and keynote lectures by world-renowned researchers in all fields of optics and photonics will set the quality standards of a varied and exciting scientific program.

We are honored to serve as Guest Editors of this Special Issue to be published in Sensors that will contain a selection of papers submitted and accepted at the AOP2021 conference in subjects relevant to the Sensors journal. Its main scope is to provide a timely and broad collection of the most innovative topics discussed at the latest edition of the conference related to applications of optics and photonics. We warmly invite researchers to submit their contributions, both original research articles and review papers, to this Special Issue. Topics include but are not limited to the following:

  • Nanophotonics, plasmonics, theoretical optics, and quantum and nonlinear optics;
  • Optical communications and sensors;
  • Optical fibers and applications;
  • Biophotonics and biomedical and medical applications of optics and photonics;
  • Ultrafast lasers, ultrafast optics, and power lasers;
  • Optical metrology, image processing, and industrial applications;
  • Optometry, ophthalmic optics, and color and visual sciences;
  • Optoelectronics;
  • Microwave photonics;
  • Photonics and optical instrumentation for space and astronomy;
  • Optics and photonics for smart mobility and smart cities.

Prof. Dr. Manuel Filipe P. C. M. Costa
Prof. Dr. Orlando Frazão
Prof. Dr. Rogerio Nogueira
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 2400 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

  • Nanophotonics, plasmonics, theoretical optics, and quantum and nonlinear optics 
  • Optical communications and sensors 
  • Optical fibers and applications 
  • Biophotonics and biomedical and medical applications of optics and photonics 
  • Ultrafast lasers, ultrafast optics, and power lasers 
  • Optical metrology, image processing, and industrial applications 
  • Optometry, ophthalmic optics, and color and visual sciences 
  • Optoelectronics 
  • Microwave photonics 
  • Photonics and optical instrumentation for space and astronomy 
  • Optics and photonics for smart mobility and smart cities

Published Papers (4 papers)

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Research

Article
Detection of 2-Furaldehyde in Milk by MIP-Based POF Chips Combined with an SPR-POF Sensor
Sensors 2022, 22(21), 8289; https://doi.org/10.3390/s22218289 - 28 Oct 2022
Viewed by 427
Abstract
An innovative optical-chemical sensor has been used to detect the 2-furaldehyde (2-FAL) in milk. The proposed sensing approach exploits the refractive index changing in a microstructured chip based on a plastic optical fiber (POF) with orthogonal micro-holes containing a specific molecularly imprinted polymer [...] Read more.
An innovative optical-chemical sensor has been used to detect the 2-furaldehyde (2-FAL) in milk. The proposed sensing approach exploits the refractive index changing in a microstructured chip based on a plastic optical fiber (POF) with orthogonal micro-holes containing a specific molecularly imprinted polymer (MIP). This POF-MIP chemical chip modifies the surface plasmon resonance (SPR) phenomena excited in another sensor chip realized in POFs (SPR-POF) and connected in series. The proposed sensor configuration exploits MIP receptors avoiding any modification of the gold film of the SPR platform. This work reports the performance, particularly the high sensitivity and low detection limit, in complex matrices such as buffalo milk fortified with 2-FAL and in different commercial kinds of cow milk thermally treated for pasteurization. The measurements were carried out in about ten minutes by dropping the solution under-test on the planar D-shaped POF surface of the chemical chip. In contrast, on the gold surface of the SPR-POF platform, a water drop is always placed to excite the SPR phenomenon, which is modulated by the chemical chip via MIP-2-FAL binding. Furthermore, the experimental results demonstrated the pros and cons of the proposed sensor system. Thanks to the high sensitivity of the sensor system, the detection of 2-FAL in the diluted milk sample (1:50) was achieved. The dilution is required to reduce the interferent effect of the complex matrix. Full article
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Article
Optical Strain Gauge Prototype Based on a High Sensitivity Balloon-like Interferometer and Additive Manufacturing
Sensors 2022, 22(19), 7652; https://doi.org/10.3390/s22197652 - 09 Oct 2022
Viewed by 459
Abstract
An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, [...] Read more.
An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber’s curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/μϵ. Full article
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Article
Optimization of Au:CuO Thin Films by Plasma Surface Modification for High-Resolution LSPR Gas Sensing at Room Temperature
Sensors 2022, 22(18), 7043; https://doi.org/10.3390/s22187043 - 17 Sep 2022
Cited by 1 | Viewed by 545
Abstract
In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on the [...] Read more.
In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on the surface properties of the plasmonic thin films was studied, envisaging its optimization as gas sensors. Thus, this work pretends to attain the maximum sensing response of the thin film system and to demonstrate its potential as a gas sensor. The results show that as Ar plasma treatment time increases, the host CuO matrix is etched while Au nanoparticles are uncovered, which leads to an enhancement of the sensitivity until a certain limit. Above such a time limit for plasma treatment, the CuO bonds are broken, and oxygen is removed from the film’s surface, resulting in a decrease in the gas sensing capabilities. Hence, the importance of the host matrix for the design of the LSPR sensor is also demonstrated. CuO not only provides stability and protection to the Au NPs but also promotes interactions between the thin film’s surface and the tested gases, thereby improving the nanocomposite film’s sensitivity. The optimized sensor sensitivity was estimated at 849 nm/RIU, which demonstrates that the Au-CuO thin films have the potential to be used as an LSPR platform for gas sensors. Full article
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Article
Development of Capacitive-Type Sensors by Electrochemical Anodization: Humidity and Touch Sensing Applications
Sensors 2021, 21(21), 7317; https://doi.org/10.3390/s21217317 - 03 Nov 2021
Cited by 1 | Viewed by 1156
Abstract
This work describes the development of a capacitive-type sensor created from nanoporous anodic aluminium oxide (NP-AAO) prepared by the one-step anodization method conducted in potentiostatic mode and performed in a low-cost homemade system. A series of samples were prepared via an anodization campaign [...] Read more.
This work describes the development of a capacitive-type sensor created from nanoporous anodic aluminium oxide (NP-AAO) prepared by the one-step anodization method conducted in potentiostatic mode and performed in a low-cost homemade system. A series of samples were prepared via an anodization campaign carried out on different acid electrolytes, in which the anodization parameters were adjusted to investigate the effect of pore size and porosity on the capacitive sensing performance. Two sensor test cases are investigated. The first case explores the use of highly uniform NP-AAO structures for humidity sensing applications while the second analyses the use of NP-AAO as a capacitive touch sensor for biological applications, namely, to detect the presence of small “objects” such as bacterial colonies of Escherichia Coli. A mathematical model based on equivalent electrical circuits was developed to evaluate the effect of humidity condensation (inside the pores) on the sensor capacitance and also to estimate the capacitance change of the sensor due to pore blocking by the presence of a certain number of bacterial microorganisms. Regarding the humidity sensing test cases, it was found that the sensitivity of the sensor fabricated in a phosphoric acid solution reaches up to 39 (pF/RH%), which is almost three times higher than the sensor fabricated in oxalic acid and about eight times higher than the sensor fabricated in sulfuric acid. Its improved sensitivity is explained in terms of the pore size effect on the mean free path and the loss of Brownian energy of the water vapour molecules. Concerning the touch sensing test case, it is demonstrated that the NP-AAO structures can be used as capacitive touch sensors because the magnitude of the capacitance change directly depends on the number of bacteria that cover the nanopores; the fraction of the electrode area activated by bacterial pore blocking is about 4.4% and 30.2% for B1 (E. Coli OD600nm = 0.1) and B2 (E. Coli OD600nm = 1) sensors, respectively. Full article
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