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Special Issue "Calibration of Chemical Sensors Based on Photoluminescence"

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

Deadline for manuscript submissions: closed (30 June 2020).

Special Issue Editors

Dr. Ángel De La Torre
Website
Guest Editor
Department of Signal Theory, University of Granada, Granada, Spain
Interests: signal processing and its application for chemical sensors; luminescence; instrumentation; audiology; seismicity; speech recognition; and location systems
Dr. Jorge F. Fernandez-Sanchez
Website
Guest Editor
Facultad de Ciencias, University of Granada, Granada, Spain
Interests: : luminescence; smart materials; nanotechnology; optical sensor; biochemical sensors; oxygen transduction; portable devices

Special Issue Information

Dear Colleagues,

Nowadays, photoluminescence sensors offer a wide range of possibilities for chemical sensing. The optimal design of a chemical sensor based on photoluminescence involves the selection of a luminescent dye and immobilizing matrix (appropriate for the target analyte and the measuring conditions), optoelectronics transducers, measuring magnitudes (intensity or lifetime), and procedures (either in the time or frequency domain), taking into consideration the measuring range, required accuracy, and cost of the instrument. As in any measuring system, the analyte determination requires, in addition to the measurement of the luminescent response, a calibration of the sensor.

Calibration is one of the current challenges in photoluminescence sensors, because of the degradation of many dyes, the costs associated to calibration, or the deviation of the calibration curves from theoretical models for particular immobilizing matrices, for extreme ranges of the analyte concentration, or because of interfering processes.

The aim of this Special Issue is to reflect on the latest improvements in the calibration of photoluminescence sensors, encompassing the application of novel strategies in order to simplify the calibration, as well as to allow for the miniaturization and simplification of chemical devices.

The Special Issue is dedicated to presenting robust strategies and statistically sound analysis procedures so as to calibrate photoluminescence sensors, including the estimation of intensity, lifetime, ratio measurements, self-referenced strategies, estimation of sensitivity, error evaluation, and any other related aspect, which should rely on the integration between statistical strategies and real measurements. Studies based on the application of novel strategies of the calibration and measurements of real samples, including comparisons of standard methodologies, are welcome.

In this framework, we are glad to edit this Special Issue on “Calibration of Chemical Sensors Based on Photoluminescence". We invite manuscripts on all aspects pertinent to the calibration of photoluminescence optical sensors. Both reviews and original research articles are welcome.

If you have any suggestions that you would like to discuss beforehand, please feel free to contact us. We look forward to and welcome your participation in this Special Issue.

Dr. Ángel De La Torre
Dr. Jorge F. Fernandez-Sanchez
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 papers will be 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 2000 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

  • Models describing photoluminescence and quenching
  • Calibration methods for photoluminescence sensors
  • Self-referenced calibration methods
  • Calibration of ratiometric photoluminescence methods
  • Effect of immobilizing matrices on luminescence, quenching, and calibration
  • Degradation of the sensing phase and re-calibration
  • Characterization of sensing phases and photoluminescence chemical sensors
  • Calibration using a small dataset
  • Calibration for microfluidic, optical-fiber, and miniaturized sensors
  • Interference in photoluminescence and multi-parametric chemical sensors
  • Calibration for very low-concentration and high-accuracy sensors
  • Managing the uncertainty in photoluminescence sensors measurements

Published Papers (4 papers)

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Research

Open AccessArticle
Self-Referenced Multifrequency Phase-Resolved Luminescence Spectroscopy
Sensors 2020, 20(19), 5482; https://doi.org/10.3390/s20195482 - 24 Sep 2020
Abstract
Phase-resolved luminescence chemical sensors provide the analyte determination based on the estimation of the luminescence lifetime. The lifetime is estimated from an analysis of the amplitudes and/or phases of the excitation and emission signals at one or several modulation frequencies. This requires recording [...] Read more.
Phase-resolved luminescence chemical sensors provide the analyte determination based on the estimation of the luminescence lifetime. The lifetime is estimated from an analysis of the amplitudes and/or phases of the excitation and emission signals at one or several modulation frequencies. This requires recording both the excitation signal (used to modulate the light source) and the emission signal (obtained from an optical transducer illuminated by the luminescent sensing phase). The excitation signal is conventionally used as reference, in order to obtain the modulation factor (the ratio between the emission and the excitation amplitudes) and/or the phase shift (the difference between the emission and the excitation phases) at each modulation frequency, which are used to estimate the luminescence lifetime. In this manuscript, we propose a new method providing the luminescence lifetimes (based either on amplitudes or phases) using only the emission signal (i.e., omitting the excitation signal in the procedure). We demonstrate that the luminescence lifetime can be derived from the emission signal when it contains at least two harmonics, because in this case the amplitude and phase of one of the harmonics can be used as reference. We present the theoretical formulation as well as an example of application to an oxygen measuring system. The proposed self-referenced lifetime estimation provides two practical advantages for luminescence chemical sensors. On one hand, it simplifies the instrument architecture, since only one analog-to-digital converter (for the emission signal) is necessary. On the other hand, the self-referenced estimation of the lifetime improves the robustness against degradation of the sensing phase or variations in the optical coupling, which reduces the recalibration requirements when the lifetimes are based on amplitudes. Full article
(This article belongs to the Special Issue Calibration of Chemical Sensors Based on Photoluminescence)
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Open AccessArticle
A Polynomial-Exponent Model for Calibrating the Frequency Response of Photoluminescence-Based Sensors
Sensors 2020, 20(16), 4635; https://doi.org/10.3390/s20164635 - 18 Aug 2020
Cited by 1
Abstract
In this work, we propose a new model describing the relationship between the analyte concentration and the instrument response in photoluminescence sensors excited with modulated light sources. The concentration is modeled as a polynomial function of the analytical signal corrected with an exponent, [...] Read more.
In this work, we propose a new model describing the relationship between the analyte concentration and the instrument response in photoluminescence sensors excited with modulated light sources. The concentration is modeled as a polynomial function of the analytical signal corrected with an exponent, and therefore the model is referred to as a polynomial-exponent (PE) model. The proposed approach is motivated by the limitations of the classical models for describing the frequency response of the luminescence sensors excited with a modulated light source, and can be considered as an extension of the Stern–Volmer model. We compare the calibration provided by the proposed PE-model with that provided by the classical Stern–Volmer, Lehrer, and Demas models. Compared with the classical models, for a similar complexity (i.e., with the same number of parameters to be fitted), the PE-model improves the trade-off between the accuracy and the complexity. The utility of the proposed model is supported with experiments involving two oxygen-sensitive photoluminescence sensors in instruments based on sinusoidally modulated light sources, using four different analytical signals (phase-shift, amplitude, and the corresponding lifetimes estimated from them). Full article
(This article belongs to the Special Issue Calibration of Chemical Sensors Based on Photoluminescence)
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Open AccessArticle
Development of an Aptamer Based Luminescent Optical Fiber Sensor for the Continuous Monitoring of Hg2+ in Aqueous Media
Sensors 2020, 20(8), 2372; https://doi.org/10.3390/s20082372 - 22 Apr 2020
Cited by 3
Abstract
A fluorescent optical fiber sensor for the detection of mercury (Hg2+) ions in aqueous solutions is presented in this work. The sensor was based on a fluorophore-labeled thymine (T)-rich oligodeoxyribonucleotide (ON) sequence that was directly immobilized onto the tip of a [...] Read more.
A fluorescent optical fiber sensor for the detection of mercury (Hg2+) ions in aqueous solutions is presented in this work. The sensor was based on a fluorophore-labeled thymine (T)-rich oligodeoxyribonucleotide (ON) sequence that was directly immobilized onto the tip of a tapered optical fiber. In the presence of mercury ions, the formation of T–Hg2+-T mismatches quenches the fluorescence emission by the labeled fluorophore, which enables the measurement of Hg2+ ions in aqueous solutions. Thus, in contrast to commonly designed sensors, neither a fluorescence quencher nor a complementary ON sequence is required. The sensor presented a response time of 24.8 seconds toward 5 × 10−12 M Hg2+. It also showed both good reversibility (higher than the 95.8%) and selectivity: the I0/I variation was 10 times higher for Hg2+ ions than for Mn2+ ions. Other contaminants examined (Co2+, Ag+, Cd2+, Ni2+, Ca2+, Pb2+, Mn2+, Zn2+, Fe3+, and Cu2+) presented an even lower interference. The limit of detection of the sensor was 4.73 × 10−13 M Hg2+ in buffer solution and 9.03 × 10−13 M Hg2+ in ultrapure water, and was also able to detect 5 × 10−12 M Hg2+ in tap water. Full article
(This article belongs to the Special Issue Calibration of Chemical Sensors Based on Photoluminescence)
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Open AccessArticle
An Effective Optical Dual Gas Sensor for Simultaneous Detection of Oxygen and Ammonia
Sensors 2019, 19(23), 5124; https://doi.org/10.3390/s19235124 - 22 Nov 2019
Cited by 3
Abstract
The development of a simple, low-cost sensor for the effective sensing of multiple gases in industrial or residential zones has been in high demand in recent days. In this article, we have proposed an optical sensor for the dual sensing of oxygen (O [...] Read more.
The development of a simple, low-cost sensor for the effective sensing of multiple gases in industrial or residential zones has been in high demand in recent days. In this article, we have proposed an optical sensor for the dual sensing of oxygen (O2) and ammonia (NH3) gases, which consists of oxygen and ammonia-sensitive fluorescent dyes coated individually on both sides of a glass substrate. An ethyl cellulose (EC) matrix doped with platinum (II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) serves as the oxygen-sensing material, whereas the NH3-sensing material includes an eosin Y fluorescent indicator immobilized within a cellulose acetate (CA) matrix. Both the oxygen and ammonia-sensitive materials were excited by the same LED light source with a 405 nm peak wavelength, while the corresponding emissions were detected separately for the selective sensing of the gases under study. The dual gas sensor exhibits maximum sensitivities of around 60 and 20 for oxygen and ammonia gases, respectively. The high sensitivity and selectivity of the proposed optical dual sensor suggests the feasibility of the simultaneous sensing of oxygen and ammonia for practical applications. Full article
(This article belongs to the Special Issue Calibration of Chemical Sensors Based on Photoluminescence)
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