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Olfactory and Gustatory Sensors

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

Deadline for manuscript submissions: closed (30 August 2016) | Viewed by 70948

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Special Issue Editors

Dr. Takeshi Onodera

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Guest Editor

Research and Development Center for Taste and Odor Sensing Kyushu University Fukuoka, Japan
Interests: electronic nose; SPR; environmental monitoring

Prof. Dr. Kiyoshi Toko

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Guest Editor

Division of Taste Sensor, Research and Development Center for Five-Sense Devices, Kyushu University, Fukuoka, Japan
Interests: taste sensors; electronic tongues; electronic noses; biosensors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Physical sensors to measure light, sound wave and pressure have been developed well. Various kinds of materials and measurement methods have been proposed, utilized, and then commercialized in the world. Chemical biosensors to selectively measure a chemical substance in liquid phase have also been developed, as represented by a glucose sensor using enzymes. Metal oxide semiconductor gas sensors are most popular in gas sensing.
Olfactory and gustatory senses detect chemical substances in gas and liquid phases. About 30 years ago, a new stream appeared in gas and liquid sensing in relation to these biological senses. This biomimetic technique utilizes plural semi-selective sensor electrodes, different from conventional high-selective biosensors. Using multiple sensors and statistical processing, this method makes it possible to discriminate and identify the gas or liquid samples, and furthermore quantify them. Progress of nanomaterials and computer has accelerated this method. This Special issue of Sensors will be dedicated to highlight these emerging technologies of olfactory and gustatory sensors, represented by electronic noses and electronic tongues.

Dr. Takeshi Onodera
Prof. Dr. Kiyoshi Toko
Guest Editors

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Keywords

Electronic nose

Electronic tongue

Multi-variate analysis

Taste sensor

Chemical sensors

Biosensors

Sensor network

Machine learning

Published Papers (12 papers)

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Research

4375 KiB

Open AccessArticle

Odor-Sensing System to Support Social Participation of People Suffering from Incontinence

by Alvaro Ortiz Pérez, Vera Kallfaß-de Frenes, Alexander Filbert, Janosch Kneer, Benedikt Bierer, Pirmin Held, Philipp Klein, Jürgen Wöllenstein, Dirk Benyoucef, Sigrid Kallfaß, Ulrich Mescheder and Stefan Palzer

Sensors 2017, 17(1), 58; https://doi.org/10.3390/s17010058 - 29 Dec 2016

Cited by 11 | Viewed by 7835

Abstract

This manuscript describes the design considerations, implementation, and laboratory validation of an odor sensing module whose purpose is to support people that suffer from incontinence. Because of the requirements expressed by the affected end-users the odor sensing unit is realized as a portable accessory that may be connected to any pre-existing smart device. We have opted for a low-cost, low-power consuming metal oxide based gas detection approach to highlight the viability of developing an inexpensive yet helpful odor recognition technology. The system consists of a hotplate employing, inkjet-printed p-type semiconducting layers of copper(II) oxide, and chromium titanium oxide. Both functional layers are characterized with respect to their gas-sensitive behavior towards humidity, ammonia, methylmercaptan, and dimethylsulfide and we demonstrate detection limits in the parts-per-billion range for the two latter gases. Employing a temperature variation scheme that reads out the layer’s resistivity in a steady-state, we use each sensor chip as a virtual array. With this setup, we demonstrate the feasibility of detecting odors associated with incontinence. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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2723 KiB

Open AccessArticle

Molecularly Imprinted Filtering Adsorbents for Odor Sensing

by Sho Shinohara, You Chiyomaru, Fumihiro Sassa, Chuanjun Liu and Kenshi Hayashi

Sensors 2016, 16(11), 1974; https://doi.org/10.3390/s16111974 - 23 Nov 2016

Cited by 7 | Viewed by 6274

Abstract

Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor clusters with specific molecular properties and uses this combinatorial information in odor discrimination. This suggests that measurement and clustering of odor molecular properties (e.g., polarity, size) using an artificial sensor is a promising approach to odor sensing. Here, adsorbents composed of composite materials with molecular recognition properties were developed for odor sensing. The selectivity of the sensor depends on the adsorbent materials, so specific polymeric materials with particular solubility parameters were chosen to adsorb odorants with various properties. The adsorption properties of the adsorbents could be modified by mixing adsorbent materials. Moreover, a novel molecularly imprinted filtering adsorbent (MIFA), composed of an adsorbent substrate covered with a molecularly imprinted polymer (MIP) layer, was developed to improve the odor molecular recognition ability. The combination of the adsorbent and MIP layer provided a higher specificity toward target molecules. The MIFA thus provides a useful technique for the design and control of adsorbents with adsorption properties specific to particular odor molecules. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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2716 KiB

Open AccessArticle

Colorimetric Analysis of Ochratoxin A in Beverage Samples

by Diana Bueno, Luis F. Valdez, Juan Manuel Gutiérrez Salgado, Jean Louis Marty and Roberto Muñoz

Sensors 2016, 16(11), 1888; https://doi.org/10.3390/s16111888 - 10 Nov 2016

Cited by 14 | Viewed by 6133

Abstract

This manuscript describes the use of a portable and low cost fluorescence setup to quantify the concentration of ochratoxin A (OTA) in beverage samples using an in-house developed system and different color models. It is reported that OTA is naturally fluorescent, for that reason an ultraviolet light at 365 nm was used to excite the samples and a Complementary Metal Oxide Semiconductor (CMOS) sensor was used to get a photograph of the OTA under excitation conditions, which is controlled by an executable interface designed in MATLAB. For each concentration of OTA, the coordinates with respect to each model color were obtained and plotted to quantify the mycotoxin present in the sample. It was possible to observe that despite the fact no extraction column was employed, the Red, Green, Blue (RGB) model shows a proportional relation to the evaluated concentrations. Despite the fact more analysis and other methods are required to quantify the OTA concentration, the brightness and a,b for the color-opponent dimensions (L*a*b) and Hue, Saturation, Value (HSV) tests provide results whereby it is possible to identify the concentration of OTA in beverage samples such as beer and wine. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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2731 KiB

Open AccessArticle

Portable Electronic Tongue Based on Microsensors for the Analysis of Cava Wines

by Pablo Giménez-Gómez, Roger Escudé-Pujol, Fina Capdevila, Anna Puig-Pujol, Cecilia Jiménez-Jorquera and Manuel Gutiérrez-Capitán

Sensors 2016, 16(11), 1796; https://doi.org/10.3390/s16111796 - 27 Oct 2016

Cited by 21 | Viewed by 6305

Abstract

Cava is a quality sparkling wine produced in Spain. As a product with a designation of origin, Cava wine has to meet certain quality requirements throughout its production process; therefore, the analysis of several parameters is of great interest. In this work, a portable electronic tongue for the analysis of Cava wine is described. The system is comprised of compact and low-power-consumption electronic equipment and an array of microsensors formed by six ion-selective field effect transistors sensitive to pH, Na⁺, K⁺, Ca²⁺, Cl⁻, and CO₃²⁻, one conductivity sensor, one redox potential sensor, and two amperometric gold microelectrodes. This system, combined with chemometric tools, has been applied to the analysis of 78 Cava wine samples. Results demonstrate that the electronic tongue is able to classify the samples according to the aging time, with a percentage of correct prediction between 80% and 96%, by using linear discriminant analysis, as well as to quantify the total acidity, pH, volumetric alcoholic degree, potassium, conductivity, glycerol, and methanol parameters, with mean relative errors between 2.3% and 6.0%, by using partial least squares regressions. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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1945 KiB

Open AccessArticle

Chocolate Classification by an Electronic Nose with Pressure Controlled Generated Stimulation

by Luis F. Valdez and Juan Manuel Gutiérrez

Sensors 2016, 16(10), 1745; https://doi.org/10.3390/s16101745 - 20 Oct 2016

Cited by 19 | Viewed by 5285

Abstract

In this work, we will analyze the response of a Metal Oxide Gas Sensor (MOGS) array to a flow controlled stimulus generated in a pressure controlled canister produced by a homemade olfactometer to build an E-nose. The built E-nose is capable of chocolate identification between the 26 analyzed chocolate bar samples and four features recognition (chocolate type, extra ingredient, sweetener and expiration date status). The data analysis tools used were Principal Components Analysis (PCA) and Artificial Neural Networks (ANNs). The chocolate identification E-nose average classification rate was of 81.3% with 0.99 accuracy (Acc), 0.86 precision (Prc), 0.84 sensitivity (Sen) and 0.99 specificity (Spe) for test. The chocolate feature recognition E-nose gives a classification rate of 85.36% with 0.96 Acc, 0.86 Prc, 0.85 Sen and 0.96 Spe. In addition, a preliminary sample aging analysis was made. The results prove the pressure controlled generated stimulus is reliable for this type of studies. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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3248 KiB

Open AccessFeature PaperArticle

Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy

by Magdalena Śliwińska, Celia Garcia-Hernandez, Mikołaj Kościński, Tomasz Dymerski, Waldemar Wardencki, Jacek Namieśnik, Małgorzata Śliwińska-Bartkowiak, Stefan Jurga, Cristina Garcia-Cabezon and Maria Luz Rodriguez-Mendez

Sensors 2016, 16(10), 1654; https://doi.org/10.3390/s16101654 - 09 Oct 2016

Cited by 13 | Viewed by 5818

Abstract

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin–Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content—the most important parameters to be measured in this type of liqueurs. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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1467 KiB

Open AccessArticle

An Exploration of the Metal Dependent Selectivity of a Metalloporphyrins Coated Quartz Microbalances Array

by Alexandro Catini, Raj Kumar, Rosamaria Capuano, Eugenio Martinelli, Roberto Paolesse and Corrado Di Natale

Sensors 2016, 16(10), 1640; https://doi.org/10.3390/s16101640 - 04 Oct 2016

Cited by 16 | Viewed by 4035

Abstract

Several studies in the last two decades have demonstrated that metalloporphyrins coated quartz microbalances can be fruitfully used in many diverse applications, spanning from medical diagnosis to environmental control. This large versatility is due to the combination of the ﬂexibility of metalloporphyrins molecular design with the independence of the quartz microbalance signal from the interaction mechanisms. The nature of the metal atom in the metalloporphyrins is often indicated as one of the most effective tools to design differently selective sensors. However, the properties of sensors are also strongly affected by the characteristics of the transducer. In this paper, the role of the metal atom is investigated studying the response, to various volatile compounds, of six quartz microbalance sensors that are based on the same porphyrin but with different metals. Results show that, since quartz microbalances (QMB) transducers can sense all the interactions between porphyrin and volatile compounds, the metal ion does not completely determine the sensor behaviour. Rather, the sensors based on the same molecular ring but with different metal ions show a non-negligible common behaviour. However, even if limited, the different metals still confer peculiar properties to the sensors and might drive the sensor array identiﬁcation of the pool of tested volatile compounds. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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1273 KiB

Open AccessArticle

Influence of Experimental Conditions on Electronic Tongue Results—Case of Valsartan Minitablets Dissolution

by Małgorzata Wesoły, Anna Kluk, Małgorzata Sznitowska, Patrycja Ciosek and Wojciech Wróblewski

Sensors 2016, 16(9), 1353; https://doi.org/10.3390/s16091353 - 23 Aug 2016

Cited by 14 | Viewed by 5392

Abstract

A potentiometric electronic tongue was applied to study the release of valsartan from pharmaceutical formulations, i.e., minitablets uncoated and coated with Eudragit E. Special attention was paid to evaluate the influence of medium temperature and composition, as well as to compare the performances of the sensor arrays working in various hydrodynamic conditions. The drug dissolution profiles registered with the ion-sensitive electrodes were compared with standard dissolution tests performed with USP Apparatus 2 (paddle). Moreover, the signal changes of all sensors were processed by principal component analysis to visualize the release modifications, related to the presence of the coating agent. Finally, the importance and influence of the experimental conditions on the results obtained using potentiometric sensor arrays were discussed. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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3416 KiB

Open AccessArticle

Factors Influencing Continuous Breath Signal in Intubated and Mechanically-Ventilated Intensive Care Unit Patients Measured by an Electronic Nose

by Jan Hendrik Leopold, Ameen Abu-Hanna, Camilla Colombo, Peter J. Sterk, Marcus J. Schultz and Lieuwe D. J. Bos

Sensors 2016, 16(8), 1337; https://doi.org/10.3390/s16081337 - 22 Aug 2016

Cited by 5 | Viewed by 4796

Abstract

Introduction: Continuous breath analysis by electronic nose (eNose) technology in the intensive care unit (ICU) may be useful in monitoring (patho) physiological changes. However, the application of breath monitoring in a non-controlled clinical setting introduces noise into the data. We hypothesized that the sensor signal is influenced by: (1) humidity in the side-stream; (2) patient-ventilator disconnections and the nebulization of medication; and (3) changes in ventilator settings and the amount of exhaled CO₂. We aimed to explore whether the aforementioned factors introduce noise into the signal, and discuss several approaches to reduce this noise. Methods: Study in mechanically-ventilated ICU patients. Exhaled breath was monitored using a continuous eNose with metal oxide sensors. Linear (mixed) models were used to study hypothesized associations. Results: In total, 1251 h of eNose data were collected. First, the initial 15 min of the signal was discarded. There was a negative association between humidity and Sensor 1 (Fixed-effect β: −0.05 ± 0.002) and a positive association with Sensors 2–4 (Fixed-effect β: 0.12 ± 0.001); the signal was corrected for this noise. Outliers were most likely due to noise and therefore removed. Sensor values were positively associated with end-tidal CO₂, tidal volume and the pressure variables. The signal was corrected for changes in these ventilator variables after which the associations disappeared. Conclusion: Variations in humidity, ventilator disconnections, nebulization of medication and changes of ventilator settings indeed influenced exhaled breath signals measured in ventilated patients by continuous eNose analysis. We discussed several approaches to reduce the effects of these noise inducing variables. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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2601 KiB

Open AccessArticle

Determination of Ignitable Liquids in Fire Debris: Direct Analysis by Electronic Nose

by Marta Ferreiro-González, Gerardo F. Barbero, Miguel Palma, Jesús Ayuso, José A. Álvarez and Carmelo G. Barroso

Sensors 2016, 16(5), 695; https://doi.org/10.3390/s16050695 - 13 May 2016

Cited by 34 | Viewed by 6916

Abstract

Arsonists usually use an accelerant in order to start or accelerate a fire. The most widely used analytical method to determine the presence of such accelerants consists of a pre-concentration step of the ignitable liquid residues followed by chromatographic analysis. A rapid analytical method based on headspace-mass spectrometry electronic nose (E-Nose) has been developed for the analysis of Ignitable Liquid Residues (ILRs). The working conditions for the E-Nose analytical procedure were optimized by studying different fire debris samples. The optimized experimental variables were related to headspace generation, specifically, incubation temperature and incubation time. The optimal conditions were 115 °C and 10 min for these two parameters. Chemometric tools such as hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA) were applied to the MS data (45–200 m/z) to establish the most suitable spectroscopic signals for the discrimination of several ignitable liquids. The optimized method was applied to a set of fire debris samples. In order to simulate post-burn samples several ignitable liquids (gasoline, diesel, citronella, kerosene, paraffin) were used to ignite different substrates (wood, cotton, cork, paper and paperboard). A full discrimination was obtained on using discriminant analysis. This method reported here can be considered as a green technique for fire debris analyses. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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1280 KiB

Open AccessArticle

Enhancing Electronic Nose Performance Based on a Novel QPSO-KELM Model

by Chao Peng, Jia Yan, Shukai Duan, Lidan Wang, Pengfei Jia and Songlin Zhang

Sensors 2016, 16(4), 520; https://doi.org/10.3390/s16040520 - 11 Apr 2016

Cited by 27 | Viewed by 7069

Abstract

A novel multi-class classification method for bacteria detection termed quantum-behaved particle swarm optimization-based kernel extreme learning machine (QPSO-KELM) based on an electronic nose (E-nose) technology is proposed in this paper. Time and frequency domain features are extracted from E-nose signals used for detecting four different classes of wounds (uninfected and infected with Staphylococcu aureus, Escherichia coli and Pseudomonas aeruginosa) in this experiment. In addition, KELM is compared with five existing classification methods: Linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), extreme learning machine (ELM), k-nearest neighbor (KNN) and support vector machine (SVM). Meanwhile, three traditional optimization methods including particle swarm optimization algorithm (PSO), genetic algorithm (GA) and grid search algorithm (GS) and four kernel functions (Gaussian kernel, linear kernel, polynomial kernel and wavelet kernel) for KELM are discussed in this experiment. Finally, the QPSO-KELM model is also used to deal with another two experimental E-nose datasets in the previous experiments. The experimental results demonstrate the superiority of QPSO-KELM in various E-nose applications. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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1586 KiB

Open AccessArticle

Research on the Changes to the Lipid/Polymer Membrane Used in the Acidic Bitterness Sensor Caused by Preconditioning

by Yuhei Harada, Junpei Noda, Rui Yatabe, Hidekazu Ikezaki and Kiyoshi Toko

Sensors 2016, 16(2), 230; https://doi.org/10.3390/s16020230 - 15 Feb 2016

Cited by 13 | Viewed by 4096

Abstract

A taste sensor that uses lipid/polymer membranes can evaluate aftertastes felt by humans using Change in membrane Potential caused by Adsorption (CPA) measurements. The sensor membrane for evaluating bitterness, which is caused by acidic bitter substances such as iso-alpha acid contained in beer, needs an immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning”. However, what happens to the lipid/polymer membrane during MSG preconditioning is not clear. Therefore, we carried out three experiments to investigate the changes in the lipid/polymer membrane caused by the MSG preconditioning, i.e., measurements of the taste sensor, measurements of the amount of the bitterness substance adsorbed onto the membrane and measurements of the contact angle of the membrane surface. The CPA values increased as the preconditioning process progressed, and became stable after 3 d of preconditioning. The response potentials to the reference solution showed the same tendency of the CPA value change during the preconditioning period. The contact angle of the lipid/polymer membrane surface decreased after 7 d of MSG preconditioning; in short, the surface of the lipid/polymer membrane became hydrophilic during MSG preconditioning. The amount of adsorbed iso-alpha acid was increased until 5 d preconditioning, and then it decreased. In this study, we revealed that the CPA values increased with the progress of MSG preconditioning in spite of the decrease of the amount of iso-alpha acid adsorbed onto the lipid/polymer membrane, and it was indicated that the CPA values increase because the sensor sensitivity was improved by the MSG preconditioning. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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