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Optical Sensors, Biosensors and Sensing Methodologies: Novel Materials, Approaches, Configurations and Applications

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

Deadline for manuscript submissions: closed (30 October 2019) | Viewed by 49592

Special Issue Editors


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Guest Editor
Department of Engineering, University of Campania Luigi Vanvitelli, Via Roma 29, 81031 Aversa, Italy
Interests: optical sensors; biosensors and chemical sensors; optical fiber sensors and optoelectronic devices
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
1. Department of Engineering, University of Campania “Luigi Vanvitelli”, Via Roma 29, 81031 Aversa, Italy
2. IREA-CNR, Via Diocleziano 328, 80124 Napoli, Italy
Interests: optical fiber sensors; distributed optical fiber sensors; nano and micro sensors; biosensors and chemical sensors; integrated optics sensors and optoelectronic devices
Special Issues, Collections and Topics in MDPI journals
Department of Electric, Electronic and Information Engineering (DIEEI), University of Catania, Catania, Italy
Interests: smart sensing systems and readout electronics; assistive technologies; nano and micro sensors; µ-fluidics; bio-sensors; inkjet printed sensors and flexible sensors; sensors exploiting innovative materials (ferrofluids, ferroelectrics and multiferroics); sensor networks; smart signal processing and nonlinear techniques (including stochastic resonance and dithering) to improve performances of sensors and bio-receptors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Novel sensing methodologies based on optical sensors are used in numerous important fields, including pharmaceutical research, medical diagnostics, environmental monitoring, agriculture, industrial applications, food safety and security.

This Special Issue was created in an interdisciplinary approach, typical of sensor science. It includes several topics covering the main features in the sensor field. In fact, the aim of this Special Issue is to bring together researchers active in the development of innovative optical transducer schemes, materials, and applications.

Works dealing with all the features of this technology are sought, including but not limited to, recent developments in: New configurations based on optical sensors, hybrid devices, novel experimental setup to improve the sensitivity, miniaturization, multiplexing capabilities and microfluidic integration, optical integrated biosensor systems (lab-on-chip), new bio/chemical receptors for optical sensors and new optical devices for biochemical sensing.

Both review articles and original research papers are solicited. There is particular interest in papers concerning new applications and innovative approaches in sensor science based on optical platforms.

Dr. Nunzio Cennamo
Prof. Dr. Luigi Zeni
Prof. Dr. Bruno Andò
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

  • Chemical Sensors and Biosensors
  • Nano and Micro Sensors
  • Physical Sensors
  • Optical Sensors
  • Microfluidics
  • Sensing methodologies

Published Papers (11 papers)

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Research

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10 pages, 3417 KiB  
Article
Design of Microdisk-Shaped Ge on Si Photodetector with Recess Structure for Refractive-Index Sensing
by Dongjun Seo, Chang-Soo Park and Young Min Song
Sensors 2019, 19(23), 5253; https://doi.org/10.3390/s19235253 - 29 Nov 2019
Cited by 1 | Viewed by 2749
Abstract
In this paper, we introduce a disk-shaped Ge-on-Si photodetector for refractive-index difference sensing at an operating wavelength of 1550 nm. For the implementation of a small-scale sensor, a Ge layer was formed on top of a Si layer to increase the absorption coefficient [...] Read more.
In this paper, we introduce a disk-shaped Ge-on-Si photodetector for refractive-index difference sensing at an operating wavelength of 1550 nm. For the implementation of a small-scale sensor, a Ge layer was formed on top of a Si layer to increase the absorption coefficient at the expense of the light-detection area. Additionally, the sensor had a ring waveguide structure along the edge of the disk formed by a recess into the inner part of the disk. This increased the interaction between the dominant optical mode traveling along the edge waveguide and the refractive index of the cladding material to be sensed, and conclusively increased detection sensitivity. The simulation results show that the proposed sensor exhibited a detection sensitivity of >50 nm/RIU (Refractive Index Unit), a quality factor of approximately 3000, and a minimum detectable refractive index change of 0.95 × 10−2 RIU with a small disk radius of 3 μm. This corresponds to 1.67 times the sensitivity without a recess (>30 nm/RIU). Full article
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13 pages, 2891 KiB  
Article
Chromatic Sensor to Determine Oxygen Presence for Applications in Intelligent Packaging
by Gracia López-Carballo, Virginia Muriel-Galet, Pilar Hernández-Muñoz and Rafael Gavara
Sensors 2019, 19(21), 4684; https://doi.org/10.3390/s19214684 - 28 Oct 2019
Cited by 17 | Viewed by 4280
Abstract
A chromatic sensor has been designed for the detection of oxygen in package headspace. The sensor is based on the redox change of methylene blue (MB) to its leuco form. Its formulation includes the pigment, glycerol, as a sacrificial electron donor, TiO2 [...] Read more.
A chromatic sensor has been designed for the detection of oxygen in package headspace. The sensor is based on the redox change of methylene blue (MB) to its leuco form. Its formulation includes the pigment, glycerol, as a sacrificial electron donor, TiO2, as a photocatalyst and ethylene-vinyl alcohol copolymer (EVOH), as a structural polymer matrix. The final sensor design that allows its manufacture by conventional printing and laminating technologies consists of the sensing polymer matrix (MB-EVOH) sandwiched in a suitable transparent multilayer structure. The outer layers protect the sensor from the external atmosphere and allow visualization of the colour. The inner layer is sufficiently opaque to facilitate sensor reading from the outside, is thick enough to avoid direct contact with food (functional barrier), and is oxygen-permeable to expose the sensing material to the internal package atmosphere. In the absence of oxygen, the sensor becomes white by irradiation with halogen lamps in less than 60 s. All components are substances permitted for food contact except the pigment, but specific migration analysis showed no trace of migration thanks to the functional barrier included in the design. Full article
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15 pages, 3014 KiB  
Communication
Hydrogel Microdomain Encapsulation of Stable Functionalized Silver Nanoparticles for SERS pH and Urea Sensing
by Alexander Quinn, Yil-Hwan You and Michael J. McShane
Sensors 2019, 19(16), 3521; https://doi.org/10.3390/s19163521 - 12 Aug 2019
Cited by 13 | Viewed by 5585
Abstract
Conceptual and commercial examples of implantable sensors have been limited to a relatively small number of target analytes, with a strong focus on glucose monitoring. Recently, surface-enhanced Raman spectroscopy (SERS) pH sensors were demonstrated to track acid-producing enzymatic reactions targeting specific analytes. We [...] Read more.
Conceptual and commercial examples of implantable sensors have been limited to a relatively small number of target analytes, with a strong focus on glucose monitoring. Recently, surface-enhanced Raman spectroscopy (SERS) pH sensors were demonstrated to track acid-producing enzymatic reactions targeting specific analytes. We show here that SERS pH tracking in the basic regime is also possible, and can be used to monitor urea concentration. To accomplish this, we developed a hydrogel consisting of polyelectrolyte multilayer microcapsules containing a SERS-sensitive pH reporter (4-mercapopyridine capped silver nanoparticles modified with bovine serum albumin). This pH sensing material exhibited a sensitive Raman scattering response to a wide range of pH from 6.5–9.7. By incorporating urease into the hydrogel matrix, the new sensor was capable of distinguishing urea concentrations of 0, 0.1, 1, and 10 mM. We also found that bovine serum albumin (BSA) prevented severe aggregation of the nanoparticle-based pH sensor, which improved sensing range and sensitivity. Furthermore, BSA safeguarded the pH sensor during the encapsulation procedure. Together, the combination of materials represents a novel approach to enabling optical sensing of reactions that generate pH changes in the basic range. Full article
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11 pages, 3315 KiB  
Article
A Direct Current Measurement Method Based on Terbium Gallium Garnet Crystal and a Double Correlation Detection Algorithm
by Yan Shen, Tong Chen, Wen-bin Yu, Jin-ming Ge, Yue Han and Fang-wei Duan
Sensors 2019, 19(13), 2997; https://doi.org/10.3390/s19132997 - 7 Jul 2019
Viewed by 2527
Abstract
When applying an optical current transformer (OCT) to direct current measurement, output signals exhibit a low signal-to-noise ratio and signal-to-noise band overlap. Sinusoidal wave modulation is used to solve this problem. A double correlation detection algorithm is used to extract the direct current [...] Read more.
When applying an optical current transformer (OCT) to direct current measurement, output signals exhibit a low signal-to-noise ratio and signal-to-noise band overlap. Sinusoidal wave modulation is used to solve this problem. A double correlation detection algorithm is used to extract the direct current (DC) signal, remove white noise and improve the signal-to-noise ratio. Our sensing unit uses a terbium gallium garnet crystal in order to increase the output signal-to-noise ratio and measurement sensitivity. Measurement errors of single correlation and double correlation detection algorithms are compared, and experimental results showed that this measurement method can control measurement error to about 0.3%, thus verifying its feasibility. Full article
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10 pages, 2565 KiB  
Article
Design for Distributed Feedback Laser Biosensors Based on the Active Grating Model
by Bowen Wang, Yi Zhou, Zhihe Guo and Xiang Wu
Sensors 2019, 19(11), 2569; https://doi.org/10.3390/s19112569 - 5 Jun 2019
Cited by 5 | Viewed by 3542
Abstract
The distributed feedback (DFB) laser is widely used in sensing because of its portable size, simple fabrication and high sensitivity. Most theoretical design models are based on passive Bragg gratings. However, passive grating models cannot be used to predict sensor performance using the [...] Read more.
The distributed feedback (DFB) laser is widely used in sensing because of its portable size, simple fabrication and high sensitivity. Most theoretical design models are based on passive Bragg gratings. However, passive grating models cannot be used to predict sensor performance using the important indicator of figure of merit (FOM) through theoretical calculations. To solve this problem, we replaced the passive grating with an active grating by using the imaginary part of the coupling constant that represents the value of the gain. As a comparison, the influence of the full width at half maximum (FWHM) and sensitivity were analyzed for different grating duty cycles and depths in the passive grating sensors. To obtain a higher FOM in the active grating sensors, we systematically investigated the effects of duty cycle and gain value through numerical simulations. We found that the redshift caused by a duty cycle increase can improve the sensitivity of biomolecule detection by 1.7 times. Full article
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15 pages, 4084 KiB  
Article
Support-Material-Free Microfluidics on an Electrochemical Sensors Platform by Aerosol Jet Printing
by Nicolò Giuseppe Di Novo, Edoardo Cantù, Sarah Tonello, Emilio Sardini and Mauro Serpelloni
Sensors 2019, 19(8), 1842; https://doi.org/10.3390/s19081842 - 18 Apr 2019
Cited by 34 | Viewed by 5551
Abstract
Printed electronics have led to new possibilities in the detection and quantification of a wide range of molecules important for medical, biotechnological, and environmental fields. The integration with microfluidics is often adopted to avoid hand-deposition of little volumes of reagents and samples on [...] Read more.
Printed electronics have led to new possibilities in the detection and quantification of a wide range of molecules important for medical, biotechnological, and environmental fields. The integration with microfluidics is often adopted to avoid hand-deposition of little volumes of reagents and samples on miniaturized electrodes that strongly depend on operator’s skills. Here we report design, fabrication and test of an easy-to-use electrochemical sensor platform with microfluidics entirely realized with Aerosol Jet Printing (AJP). We printed a six-electrochemical-sensors platform with AJP and we explored the possibility to aerosol jet print directly on it a microfluidic structure without any support material. Thus, the sacrificial material removal and/or the assembly with sensors steps are avoided. The repeatability observed when printing both conductive and ultraviolet (UV)-curable polymer inks can be supported from the values of relative standard deviation of maximum 5% for thickness and 9% for line width. We designed the whole microfluidic platform to make the sample deposition (20 μL) independent from the operator. To validate the platform, we quantified glucose at different concentrations using a standard enzyme-mediated procedure. Both mediator and enzyme were directly aerosol jet printed on working electrodes (WEs), thus the proposed platform is entirely fabricated by AJP and ready to use. The chronoamperometric tests show limit of detection (LOD) = 2.4 mM and sensitivity = 2.2 ± 0.08 µA/mM confirming the effectiveness of mediator and enzyme directly aerosol jet printed to provide sensing in a clinically relevant range (3–10 mM). The average relative standard inter-platform deviation is about 8%. AJP technique can be used for fabricating a ready-to-use microfluidic device that does not need further processing after fabrication, but is promptly available for electrochemical sample analysis. Full article
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34 pages, 22213 KiB  
Article
A Knowledge-Driven Approach for 3D High Temporal-Spatial Measurement of an Arbitrary Contouring Error of CNC Machine Tools Using Monocular Vision
by Xiao Li, Wei Liu, Yi Pan, Jianwei Ma and Fuji Wang
Sensors 2019, 19(3), 744; https://doi.org/10.3390/s19030744 - 12 Feb 2019
Cited by 14 | Viewed by 4894
Abstract
Periodic health checks of contouring errors under unloaded conditions are critical for machine performance evaluation and value-added manufacturing. Aiming at breaking the dimension, range and speed measurement limitations of the existing devices, a cost-effective knowledge-driven approach for detecting error motions of arbitrary paths [...] Read more.
Periodic health checks of contouring errors under unloaded conditions are critical for machine performance evaluation and value-added manufacturing. Aiming at breaking the dimension, range and speed measurement limitations of the existing devices, a cost-effective knowledge-driven approach for detecting error motions of arbitrary paths using a single camera is proposed. In combination with the PNP algorithm, the three-dimensional (3D) evaluation of large-scale contouring error in relatively high feed rate conditions can be deduced from a priori geometrical knowledge. The innovations of this paper focus on improving the accuracy, efficiency and ability of the vision measurement. Firstly, a camera calibration method considering distortion partition of the depth-of-field (DOF) is presented to give an accurate description of the distortion behavior in the entire photography domain. Then, to maximize the utilization of the decimal involved in the feature encoding, new high-efficient encoding markers are designed on a cooperative target to characterize motion information of the machine. Accordingly, in the image processing, markers are automatically identified and located by the proposed decoding method based on finding the optimal start bit. Finally, with the selected imaging parameters and the precalibrated position of each marker, the 3D measurement of large-scale contouring error under relatively high dynamic conditions can be realized by comparing the curve that is measured by PNP algorithm with the nominal one. Both detection and verification experiments are conducted for two types of paths (i.e., planar and spatial trajectory), and experimental results validate the measurement accuracy and advantages of the proposed method. Full article
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10 pages, 2468 KiB  
Article
Colorimetric and Ratiometric Fluorescence Dual-Mode Sensing of Glucose Based on Carbon Quantum Dots and Potential UV/Fluorescence of o-Diaminobenzene
by Hong Zhai, Yunfeng Bai, Jun Qin and Feng Feng
Sensors 2019, 19(3), 674; https://doi.org/10.3390/s19030674 - 7 Feb 2019
Cited by 19 | Viewed by 6915
Abstract
A novel colorimetric and ratiometric fluorescence sensor was constructed by using carbon quantum dots (CQDs) and o-diaminobenzene (ODB). Unlike ODB by itself, ODB oxide (oxODB) not only emits fluorescence, but also produces ultraviolet (UV) absorption. Therefore, on the basis of the potential optical [...] Read more.
A novel colorimetric and ratiometric fluorescence sensor was constructed by using carbon quantum dots (CQDs) and o-diaminobenzene (ODB). Unlike ODB by itself, ODB oxide (oxODB) not only emits fluorescence, but also produces ultraviolet (UV) absorption. Therefore, on the basis of the potential optical properties of ODB, glucose oxidase (Gox) and horseradish peroxidase (HRP) were introduced into a CQDs–ODB system for the quantitative oxidation of ODB. When glucose is present, it is oxidized by oxygen under the catalytic action of its oxidase to form hydrogen peroxide. Hydrogen peroxide is a strong oxidant that can rapidly oxidize ODB through the catalysis of horseradish peroxidase. oxODB can cause changes in the fluorescence ratio (I550/I446) and absorbance ratio (A/A0). At the same time, the color of the detection solution can also change under sunlight and ultraviolet lamps. Therefore, glucose can be quantitatively detected by ratiometric fluorescence and colorimetry simultaneously, and semi-quantitatively detected by observing the colors with sunlight and ultraviolet lamps of 365 nm. This increases not only the convenience but also the accuracy of detection. In addition, this sensor has good selectivity and can be used for the determination of glucose in serum, providing a new idea for the development of blood glucose sensors. Full article
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12 pages, 4374 KiB  
Article
Optical Sensor for Real-Time Detection of Trichlorofluoromethane
by Maiko Girschikofsky, Dimitrij Ryvlin, Siegfried R. Waldvogel and Ralf Hellmann
Sensors 2019, 19(3), 632; https://doi.org/10.3390/s19030632 - 2 Feb 2019
Cited by 10 | Viewed by 4785
Abstract
Trichlorofluoromethane was once a promising and versatile applicable chlorofluorocarbon. Unaware of its ozone-depleting character, for a long time it was globally applied as propellant and refrigerant and thus led to significant thinning of the ozone layer and contributed to the formation of the [...] Read more.
Trichlorofluoromethane was once a promising and versatile applicable chlorofluorocarbon. Unaware of its ozone-depleting character, for a long time it was globally applied as propellant and refrigerant and thus led to significant thinning of the ozone layer and contributed to the formation of the so-called ozone hole. Although production and application of this substance were gradually reduced at an early stage, we still face the consequences of its former careless use. Today, trichlorofluoromethane is released during recycling processes of waste cooling devices, traded on the black market, and according to recent findings still illegally manufactured. Here, we present an optical sensor device for real-time in-situ detection and measurement of this environmentally harmful chlorofluorocarbon. The described sensor is based on a planar Bragg grating that is functionalized with cyclodextrin derivatives and operates on the principle of a chemical sensor. In our study, the sensor is sensitized using per-methyl-, per-ethyl-, and per-allyl-substituted α -, β -, and γ -cyclodextrins as affinity materials for airborne trichlorofluoromethane. These functional coatings have been proven to be highly efficient, as an up to 400-times stronger signal deflection could be achieved compared to an identical but uncoated sensor. The presented sensor device shows instantaneous response to trichlorofluoromethane exposure, and features a limit-of-detection of less than 25 ppm, depending on the applied affinity material. Full article
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15 pages, 9250 KiB  
Article
A Novel Vision-Based Pose Measurement Method Considering the Refraction of Light
by Wei Liu, Xin Ma, Xiao Li, Yi Pan, Fuji Wang and Zhenyuan Jia
Sensors 2018, 18(12), 4348; https://doi.org/10.3390/s18124348 - 10 Dec 2018
Cited by 4 | Viewed by 3048
Abstract
Nowadays, due to the advantages of non-contact and high-speed, vision-based pose measurements have been widely used for aircraft performance testing in a wind tunnel. However, usually glass ports are used to protect cameras against the high-speed airflow influence, which will lead to a [...] Read more.
Nowadays, due to the advantages of non-contact and high-speed, vision-based pose measurements have been widely used for aircraft performance testing in a wind tunnel. However, usually glass ports are used to protect cameras against the high-speed airflow influence, which will lead to a big measurement error. In this paper, to further improve the vision-based pose measurement accuracy, an imaging model which considers the refraction light of the observation window was proposed. In this method, a nonlinear camera calibration model considering the refraction brought by the wind tunnel observation window, was established first. What’s more, a new method for the linear calibration of the normal vector of the glass observation window was presented. Then, combining with the proposed matching method based on coplanarity constraint, the six pose parameters of the falling target could be calculated. Finally, the experimental setup was established to conduct the pose measurement study in the laboratory, and the results satisfied the application requirements. Besides, experiments for verifying the vision measurement accuracy were also performed, and the results indicated that the displacement and angle measurement accuracy approximately increased by 57% and 33.6%, respectively, which showed the high accuracy of the proposed method. Full article
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Review

Jump to: Research

23 pages, 9702 KiB  
Review
Chiroptical Sensing: A Conceptual Introduction
by Ani Ozcelik, Raquel Pereira-Cameselle, Natasa Poklar Ulrih, Ana G. Petrovic and José Lorenzo Alonso-Gómez
Sensors 2020, 20(4), 974; https://doi.org/10.3390/s20040974 - 12 Feb 2020
Cited by 20 | Viewed by 4606
Abstract
Chiroptical responses have been an essential tool over the last decades for chemical structural elucidation due to their exceptional sensitivity to geometry and intermolecular interactions. In recent times, there has been an increasing interest in the search for more efficient sensing by the [...] Read more.
Chiroptical responses have been an essential tool over the last decades for chemical structural elucidation due to their exceptional sensitivity to geometry and intermolecular interactions. In recent times, there has been an increasing interest in the search for more efficient sensing by the rational design of tailored chiroptical systems. In this review article, advances made in chiroptical systems towards their implementation in sensing applications are summarized. Strategies to generate chiroptical responses are illustrated. Theoretical approaches to assist in the design of these systems are discussed. The development of efficient chiroptical reporters in different states of matter, essential for the implementation in sensing devises, is reviewed. In the last part, remarkable examples of chiroptical sensing applications are highlighted. Full article
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