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Special Issue "Chemical Sensors based on In Situ Spectroscopy"

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

Deadline for manuscript submissions: closed (31 July 2015).

Special Issue Editors

Prof. Dr. Mark A. Arnold
Website
Guest Editor
Department of Chemistry and Optical Science and Technology Center University of Iowa Iowa City, Iowa 52242 USA
Interests: Noninvasive glucose measurements in human subjects; real-time bioreactor monitoring and control; near infrared spectroscopy; terahertz spectroscopy; dielectric spectroscopy
Prof. Dr. Hoeil Chung
Website
Guest Editor
Department of Chemistry Hanyang University 17 Haengdang-dong, Seongdong-gu Seoul, 133-791 Korea
Interests: IR and Raman spectroscopy for biomedical diagnosis; sensors based on surface enhanced Raman spectroscopy; chemometrics

Special Issue Information

Dear Colleagues,

Analytical measurements via in situ spectroscopy represent a challenging area of chemical sensor development. Such measurements involve passing a selected band of radiation through a sample and extracting the desired chemical information from the resulting spectrum. Approaches include, but are not limited to, near infrared, mid-infrared, Raman scattering, magnetic resonance, impedance, terahertz, and dielectric spectroscopies. Typically, multivariate analysis methods are required to properly extract the desired analytical information from the in situ spectra, owing to the complexity of the sample matrix. This approach offers several attractive features, including the ability to quantify multiple analytes simultaneously within the sample matrix. In addition, this spectroscopic approach is both reagentless and nondestructive, thereby enabling real-time measurements without perturbing the system under investigation. These features promise rapid, real-time analytical measurements that are well suited for in situ control of critical processes, as well as monitoring quality of supply-chain materials. For these reasons, spectroscopic sensors have been developed for a variety of applications, including those in food sciences, petroleum refining, bioprocessing, biomedical sciences, environmental monitoring, and others. Still, longstanding analytical issues remain that limit the implementation of this approach, including selectivity in complex sample matrixes, poor calibration robustness over time, sensitivity, and limits of detection.

This Special Issue of Sensors will be dedicated to advances in the contemporary development of spectroscopic chemical sensors with an emphasis on overcoming these longstanding issues as well as their applications to novel processes. Both original research reports and reviews are welcome. Research reports must advance analytical science by expanding our overall understanding of in situ measurements. Reviews must provide a critical assessment of a selected element of the field.

Prof. Dr. Mark A. Arnold
Prof. Dr. Hoeil Chung
Guest Editor
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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

  • spectroscopic sensors
  • noninvasive sensing
  • real-time monitoring
  • near-infrared spectroscopy
  • mid-infrared spectroscopy
  • Raman scattering spectroscopy
  • chemometrics

Published Papers (10 papers)

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Research

Open AccessArticle
Determination of the Mineral Composition and Toxic Element Contents of Propolis by Near Infrared Spectroscopy
Sensors 2015, 15(11), 27854-27868; https://doi.org/10.3390/s151127854 - 03 Nov 2015
Cited by 20
Abstract
The potential of near infrared spectroscopy (NIR) with remote reflectance fiber-optic probes for determining the mineral composition of propolis was evaluated. This technology allows direct measurements without prior sample treatment. Ninety one samples of propolis were collected in Chile (Bio-Bio region) and Spain [...] Read more.
The potential of near infrared spectroscopy (NIR) with remote reflectance fiber-optic probes for determining the mineral composition of propolis was evaluated. This technology allows direct measurements without prior sample treatment. Ninety one samples of propolis were collected in Chile (Bio-Bio region) and Spain (Castilla-León and Galicia regions). The minerals measured were aluminum, calcium, iron, potassium, magnesium, phosphorus, and some potentially toxic trace elements such as zinc, chromium, nickel, copper and lead. The modified partial least squares (MPLS) regression method was used to develop the NIR calibration model. The determination coefficient (R2) and root mean square error of prediction (RMSEP) obtained for aluminum (0.79, 53), calcium (0.83, 94), iron (0.69, 134) potassium (0.95, 117), magnesium (0.70, 99), phosphorus (0.94, 24) zinc (0.87, 10) chromium (0.48, 0.6) nickel (0.52, 0.7) copper (0.64, 0.9) and lead (0.70, 2) in ppm. The results demonstrated that the capacity for prediction can be considered good for wide ranges of potassium, phosphorus and zinc concentrations, and acceptable for aluminum, calcium, magnesium, iron and lead. This indicated that the NIR method is comparable to chemical methods. The method is of interest in the rapid prediction of potentially toxic elements in propolis before consumption. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Nitric Oxide Isotopic Analyzer Based on a Compact Dual-Modulation Faraday Rotation Spectrometer
Sensors 2015, 15(10), 25992-26008; https://doi.org/10.3390/s151025992 - 14 Oct 2015
Cited by 7
Abstract
We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv·Hz [...] Read more.
We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv·Hz−1/2, corresponding to noise-equivalent Faraday rotation angle (NEA) of 1.31 × 10−8 rad·Hz−1/2 and noise-equivalent absorbance (αL)min of 6.27 × 10−8 Hz−1/2. White-noise limited performance at 2.8× the shot-noise limit is observed up to ~1000 s, allowing reliable calibration and sample measurement within the drift-free interval of the spectrometer. Integration with wet-chemistry based on acidic vanadium(III) enables conversion of aqueous nitrate/nitrite samples to gaseous NO for total nitrogen isotope analysis. Isotopic ratiometry is accomplished via time-multiplexed measurements of two NO isotope transitions. For 5 μmol potassium nitrate samples, the instrument consistently yields ratiometric precision below 0.3‰, thus demonstrating potential as an in situ diagnostic tool for environmental nitrogen cycle studies. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
A Wireless Multi-Sensor Dielectric Impedance Spectroscopy Platform
Sensors 2015, 15(9), 23572-23588; https://doi.org/10.3390/s150923572 - 17 Sep 2015
Cited by 7
Abstract
This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee [...] Read more.
This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Improving the Detection Limit in a Capillary Raman System for In Situ Gas Analysis by Means of Fluorescence Reduction
Sensors 2015, 15(9), 23110-23125; https://doi.org/10.3390/s150923110 - 11 Sep 2015
Cited by 10
Abstract
Raman spectroscopy for low-pressure or trace gas analysis is rather challenging, in particular in process control applications requiring trace detection and real-time response; in general, enhancement techniques are required. One possible enhancement approach which enjoys increasing popularity makes use of an internally-reflective capillary [...] Read more.
Raman spectroscopy for low-pressure or trace gas analysis is rather challenging, in particular in process control applications requiring trace detection and real-time response; in general, enhancement techniques are required. One possible enhancement approach which enjoys increasing popularity makes use of an internally-reflective capillary as the gas cell. However, in the majority of cases, such capillary systems were often limited in their achievable sensitivity by a significant fluorescence background, which is generated as a consequence of interactions between the laser light and optical glass components in the setup. In order to understand and counteract these problems we have investigated a range of fluorescence-reducing measures, including the rearrangement of optical elements, and the replacement of glass components—including the capillary itself—by metal alternatives. These studies now have led to a capillary setup in which fluorescence is practically eliminated and substantial signal enhancement over standard Raman setups is achieved. With this improved (prototype) setup, detection limits of well below 1 mbar could be obtained in sub-second acquisition times, demonstrating the potential of capillary Raman spectroscopy for real-time, in situ gas sensing and process control applications, down to trace level concentrations. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
New Opportunities in Mid-Infrared Emission Control
Sensors 2015, 15(9), 22724-22736; https://doi.org/10.3390/s150922724 - 09 Sep 2015
Cited by 18
Abstract
Tunable laser absorption spectroscopy (TLAS) has been well accepted as a preferred measurement technique for many industrial applications in recent years, especially for in situ applications. Previously, mainly near-infrared lasers have been used in TLAS sensors. The advent of compact mid-infrared light sources, [...] Read more.
Tunable laser absorption spectroscopy (TLAS) has been well accepted as a preferred measurement technique for many industrial applications in recent years, especially for in situ applications. Previously, mainly near-infrared lasers have been used in TLAS sensors. The advent of compact mid-infrared light sources, like quantum cascade lasers and interband cascade lasers, has made it possible to detect gases with better sensitivity by utilizing fundamental absorption bands and to measure species that do not have any absorption lines in the near-infrared spectral region. This technological advancement has allowed developing new sensors for gases, such as nitric oxide and sulfur dioxide, for industrial applications. Detection limits of better than 1 ppm·m for nitric oxide and better than 10 ppm·m for sulfur dioxide are demonstrated in field experiments. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Field Test of a Remote Multi-Path CLaDS Methane Sensor
Sensors 2015, 15(9), 21315-21326; https://doi.org/10.3390/s150921315 - 28 Aug 2015
Cited by 14
Abstract
Existing technologies for quantifying methane emissions are often limited to single point sensors, making large area environmental observations challenging. We demonstrate the operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy (CLaDS) for quantification of atmospheric methane concentrations over extended areas, [...] Read more.
Existing technologies for quantifying methane emissions are often limited to single point sensors, making large area environmental observations challenging. We demonstrate the operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy (CLaDS) for quantification of atmospheric methane concentrations over extended areas, a technology that shows potential for monitoring emissions from wetlands. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Application of Visible and Near-Infrared Hyperspectral Imaging to Determine Soluble Protein Content in Oilseed Rape Leaves
Sensors 2015, 15(7), 16576-16588; https://doi.org/10.3390/s150716576 - 09 Jul 2015
Cited by 41
Abstract
Visible and near-infrared hyperspectral imaging covering spectral range of 380–1030 nm as a rapid and non-destructive method was applied to estimate the soluble protein content of oilseed rape leaves. Average spectrum (500–900 nm) of the region of interest (ROI) of each sample was [...] Read more.
Visible and near-infrared hyperspectral imaging covering spectral range of 380–1030 nm as a rapid and non-destructive method was applied to estimate the soluble protein content of oilseed rape leaves. Average spectrum (500–900 nm) of the region of interest (ROI) of each sample was extracted, and four samples out of 128 samples were defined as outliers by Monte Carlo-partial least squares (MCPLS). Partial least squares (PLS) model using full spectra obtained dependable performance with the correlation coefficient (rp) of 0.9441, root mean square error of prediction (RMSEP) of 0.1658 mg/g and residual prediction deviation (RPD) of 2.98. The weighted regression coefficient (Bw), successive projections algorithm (SPA) and genetic algorithm-partial least squares (GAPLS) selected 18, 15, and 16 sensitive wavelengths, respectively. SPA-PLS model obtained the best performance with rp of 0.9554, RMSEP of 0.1538 mg/g and RPD of 3.25. Distribution of protein content within the rape leaves were visualized and mapped on the basis of the SPA-PLS model. The overall results indicated that hyperspectral imaging could be used to determine and visualize the soluble protein content of rape leaves. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Application of Cavity Enhanced Absorption Spectroscopy to the Detection of Nitric Oxide, Carbonyl Sulphide, and Ethane—Breath Biomarkers of Serious Diseases
Sensors 2015, 15(6), 14356-14369; https://doi.org/10.3390/s150614356 - 17 Jun 2015
Cited by 22
Abstract
The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with [...] Read more.
The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with some biomarkers showed that detection of pathogenic changes at the molecular level is possible using this technique. Thanks to cavity enhanced spectroscopy application, detection limits at the ppb-level and short measurements time (<3 s) were achieved. Absorption lines of reference samples of the selected volatile biomarkers were probed using a distributed feedback quantum cascade laser and a tunable laser system consisting of an optical parametric oscillator and difference frequency generator. Setup using the first source provided a detection limit of 30 ppb for nitric oxide and 250 ppb for carbonyl sulphide. During experiments employing a second laser, detection limits of 0.9 ppb and 0.3 ppb were obtained for carbonyl sulphide and ethane, respectively. The conducted experiments show that this type of diagnosis would significantly increase chances for effective therapy of some diseases. Additionally, it offers non-invasive and real time measurements, high sensitivity and selectivity as well as minimizing discomfort for patients. For that reason, such sensors can be used in screening for early detection of serious diseases. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
Investigation of Two Novel Approaches for Detection of Sulfate Ion and Methane Dissolved in Sediment Pore Water Using Raman Spectroscopy
Sensors 2015, 15(6), 12377-12388; https://doi.org/10.3390/s150612377 - 26 May 2015
Cited by 5
Abstract
The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42− in [...] Read more.
The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42− in pore water samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible reason for this is that the methane escaped after sampling and the remaining concentration of methane is too low to be detected. To find more effective ways to analyze the composition of pore water, two novel approaches are proposed. One is based on Liquid Core Optical Fiber (LCOF) for detection of SO42−. The other one is an enrichment process for the detection of CH4. With the aid of LCOF, the Raman signal of SO42− is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup. The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water. By CCl4 extraction, methane at a concentration below 1.14 mmol/L has been detected by conventional Raman spectroscopy. All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42− and CH4 detection in pore water. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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Open AccessArticle
A Online NIR Sensor for the Pilot-Scale Extraction Process in Fructus Aurantii Coupled with Single and Ensemble Methods
Sensors 2015, 15(4), 8749-8763; https://doi.org/10.3390/s150408749 - 14 Apr 2015
Cited by 8
Abstract
Model performance of the partial least squares method (PLS) alone and bagging-PLS was investigated in online near-infrared (NIR) sensor monitoring of pilot-scale extraction process in Fructus aurantii. High-performance liquid chromatography (HPLC) was used as a reference method to identify the active pharmaceutical [...] Read more.
Model performance of the partial least squares method (PLS) alone and bagging-PLS was investigated in online near-infrared (NIR) sensor monitoring of pilot-scale extraction process in Fructus aurantii. High-performance liquid chromatography (HPLC) was used as a reference method to identify the active pharmaceutical ingredients: naringin, hesperidin and neohesperidin. Several preprocessing methods and synergy interval partial least squares (SiPLS) and moving window partial least squares (MWPLS) variable selection methods were compared. Single quantification models (PLS) and ensemble methods combined with partial least squares (bagging-PLS) were developed for quantitative analysis of naringin, hesperidin and neohesperidin. SiPLS was compared to SiPLS combined with bagging-PLS. Final results showed the root mean square error of prediction (RMSEP) of bagging-PLS to be lower than that of PLS regression alone. For this reason, an ensemble method of online NIR sensor is here proposed as a means of monitoring the pilot-scale extraction process in Fructus aurantii, which may also constitute a suitable strategy for online NIR monitoring of CHM. Full article
(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)
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