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Sensors, Volume 15, Issue 11 (November 2015) , Pages 27393-29764

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Open AccessArticle
UAVs Task and Motion Planning in the Presence of Obstacles and Prioritized Targets
Sensors 2015, 15(11), 29734-29764; https://doi.org/10.3390/s151129734
Received: 25 June 2015 / Revised: 5 November 2015 / Accepted: 12 November 2015 / Published: 24 November 2015
Cited by 17 | Viewed by 2201 | PDF Full-text (902 KB) | HTML Full-text | XML Full-text
Abstract
The intertwined task assignment and motion planning problem of assigning a team of fixed-winged unmanned aerial vehicles to a set of prioritized targets in an environment with obstacles is addressed. It is assumed that the targets’ locations and initial priorities are determined using [...] Read more.
The intertwined task assignment and motion planning problem of assigning a team of fixed-winged unmanned aerial vehicles to a set of prioritized targets in an environment with obstacles is addressed. It is assumed that the targets’ locations and initial priorities are determined using a network of unattended ground sensors used to detect potential threats at restricted zones. The targets are characterized by a time-varying level of importance, and timing constraints must be fulfilled before a vehicle is allowed to visit a specific target. It is assumed that the vehicles are carrying body-fixed sensors and, thus, are required to approach a designated target while flying straight and level. The fixed-winged aerial vehicles are modeled as Dubins vehicles, i.e., having a constant speed and a minimum turning radius constraint. The investigated integrated problem of task assignment and motion planning is posed in the form of a decision tree, and two search algorithms are proposed: an exhaustive algorithm that improves over run time and provides the minimum cost solution, encoded in the tree, and a greedy algorithm that provides a quick feasible solution. To satisfy the target’s visitation timing constraint, a path elongation motion planning algorithm amidst obstacles is provided. Using simulations, the performance of the algorithms is compared, evaluated and exemplified. Full article
(This article belongs to the Special Issue UAV Sensors for Environmental Monitoring) Printed Edition available
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Open AccessArticle
A Modified Rife Algorithm for Off-Grid DOA Estimation Based on Sparse Representations
Sensors 2015, 15(11), 29721-29733; https://doi.org/10.3390/s151129721
Received: 17 July 2015 / Revised: 12 November 2015 / Accepted: 17 November 2015 / Published: 24 November 2015
Cited by 5 | Viewed by 1676 | PDF Full-text (712 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we address the problem of off-grid direction of arrival (DOA) estimation based on sparse representations in the situation of multiple measurement vectors (MMV). A novel sparse DOA estimation method which changes MMV problem to SMV is proposed. This method uses [...] Read more.
In this paper we address the problem of off-grid direction of arrival (DOA) estimation based on sparse representations in the situation of multiple measurement vectors (MMV). A novel sparse DOA estimation method which changes MMV problem to SMV is proposed. This method uses sparse representations based on weighted eigenvectors (SRBWEV) to deal with the MMV problem. MMV problem can be changed to single measurement vector (SMV) problem by using the linear combination of eigenvectors of array covariance matrix in signal subspace as a new SMV for sparse solution calculation. So the complexity of this proposed algorithm is smaller than other DOA estimation algorithms of MMV. Meanwhile, it can overcome the limitation of the conventional sparsity-based DOA estimation approaches that the unknown directions belong to a predefined discrete angular grid, so it can further improve the DOA estimation accuracy. The modified Rife algorithm for DOA estimation (MRife-DOA) is simulated based on SRBWEV algorithm. In this proposed algorithm, the largest and sub-largest inner products between the measurement vector or its residual and the atoms in the dictionary are utilized to further modify DOA estimation according to the principle of Rife algorithm and the basic idea of coarse-to-fine estimation. Finally, simulation experiments show that the proposed algorithm is effective and can reduce the DOA estimation error caused by grid effect with lower complexity. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
SSL: Signal Similarity-Based Localization for Ocean Sensor Networks
Sensors 2015, 15(11), 29702-29720; https://doi.org/10.3390/s151129702
Received: 1 October 2015 / Revised: 8 November 2015 / Accepted: 19 November 2015 / Published: 24 November 2015
Cited by 8 | Viewed by 2031 | PDF Full-text (5855 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, wireless sensor networks are often deployed on the sea surface for ocean scientific monitoring. One of the important challenges is to localize the nodes’ positions. Existing localization schemes can be roughly divided into two types: range-based and range-free. The range-based localization approaches [...] Read more.
Nowadays, wireless sensor networks are often deployed on the sea surface for ocean scientific monitoring. One of the important challenges is to localize the nodes’ positions. Existing localization schemes can be roughly divided into two types: range-based and range-free. The range-based localization approaches heavily depend on extra hardware capabilities, while range-free ones often suffer from poor accuracy and low scalability, far from the practical ocean monitoring applications. In response to the above limitations, this paper proposes a novel signal similarity-based localization (SSL) technology, which localizes the nodes’ positions by fully utilizing the similarity of received signal strength and the open-air characteristics of the sea surface. In the localization process, we first estimate the relative distance between neighboring nodes through comparing the similarity of received signal strength and then calculate the relative distance for non-neighboring nodes with the shortest path algorithm. After that, the nodes’ relative relation map of the whole network can be obtained. Given at least three anchors, the physical locations of nodes can be finally determined based on the multi-dimensional scaling (MDS) technology. The design is evaluated by two types of ocean experiments: a zonal network and a non-regular network using 28 nodes. Results show that the proposed design improves the localization accuracy compared to typical connectivity-based approaches and also confirm its effectiveness for large-scale ocean sensor networks. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks 2016)
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Open AccessReview
Tunable Microfluidic Devices for Hydrodynamic Fractionation of Cells and Beads: A Review
Sensors 2015, 15(11), 29685-29701; https://doi.org/10.3390/s151129685
Received: 3 September 2015 / Revised: 26 October 2015 / Accepted: 5 November 2015 / Published: 24 November 2015
Cited by 1 | Viewed by 2352 | PDF Full-text (3034 KB) | HTML Full-text | XML Full-text
Abstract
The adjustable microfluidic devices that have been developed for hydrodynamic-based fractionation of beads and cells are important for fast performance tunability through interaction of mechanical properties of particles in fluid flow and mechanically flexible microstructures. In this review, the research works reported on [...] Read more.
The adjustable microfluidic devices that have been developed for hydrodynamic-based fractionation of beads and cells are important for fast performance tunability through interaction of mechanical properties of particles in fluid flow and mechanically flexible microstructures. In this review, the research works reported on fabrication and testing of the tunable elastomeric microfluidic devices for applications such as separation, filtration, isolation, and trapping of single or bulk of microbeads or cells are discussed. Such microfluidic systems for rapid performance alteration are classified in two groups of bulk deformation of microdevices using external mechanical forces, and local deformation of microstructures using flexible membrane by pneumatic pressure. The main advantage of membrane-based tunable systems has been addressed to be the high capability of integration with other microdevice components. The stretchable devices based on bulk deformation of microstructures have in common advantage of simplicity in design and fabrication process. Full article
(This article belongs to the Special Issue Micro/Nano Fluidic Devices and Bio-MEMS)
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Open AccessArticle
The Indoor Localization and Tracking Estimation Method of Mobile Targets in Three-Dimensional Wireless Sensor Networks
Sensors 2015, 15(11), 29661-29684; https://doi.org/10.3390/s151129661
Received: 1 September 2015 / Revised: 17 November 2015 / Accepted: 18 November 2015 / Published: 24 November 2015
Cited by 5 | Viewed by 2032 | PDF Full-text (515 KB) | HTML Full-text | XML Full-text
Abstract
Indoor localization is a significant research area in wireless sensor networks (WSNs). Generally, the nodes of WSNs are deployed in the same plane, i.e., the floor, as the target to be positioned, which causes the sensing signal to be influenced or even blocked [...] Read more.
Indoor localization is a significant research area in wireless sensor networks (WSNs). Generally, the nodes of WSNs are deployed in the same plane, i.e., the floor, as the target to be positioned, which causes the sensing signal to be influenced or even blocked by unpredictable obstacles, like furniture. However, a 3D system, like Cricket, can reduce the negative impact of obstacles to the maximum extent and guarantee the sensing signal transmission by using the line of sight (LOS). However, most of the traditional localization methods are not available for the new deployment mode. In this paper, we propose the self-localization of beacons method based on the Cayley–Menger determinant, which can determine the positions of beacons stuck in the ceiling; and differential sensitivity analysis (DSA) is also applied to eliminate measurement errors in measurement data fusion. Then, the calibration of beacons scheme is proposed to further refine the locations of beacons by the mobile robot. According to the robot’s motion model based on dead reckoning, which is the process of determining one’s current position, we employ the H ∞ filter and the strong tracking filter (STF) to calibrate the rough locations, respectively. Lastly, the optimal node selection scheme based on geometric dilution precision (GDOP) is presented here, which is able to pick the group of beacons with the minimum GDOP from all of the beacons. Then, we propose the GDOP-based weighting estimation method (GWEM) to associate redundant information with the position of the target. To verify the proposed methods in the paper, we design and conduct a simulation and an experiment in an indoor setting. Compared to EKF and the H ∞ filter, the adopted STF method can more effectively calibrate the locations of beacons; GWEM can provide centimeter-level precision in 3D environments by using the combination of beacons that minimizes GDOP. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle
Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG
Sensors 2015, 15(11), 29648-29660; https://doi.org/10.3390/s151129648
Received: 27 August 2015 / Revised: 5 November 2015 / Accepted: 9 November 2015 / Published: 24 November 2015
Cited by 7 | Viewed by 2229 | PDF Full-text (1515 KB) | HTML Full-text | XML Full-text
Abstract
To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 [...] Read more.
To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the “HYSY-981” ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results. Full article
(This article belongs to the Special Issue Sensors for Harsh Environments)
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Open AccessTechnical Note
Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy
Sensors 2015, 15(11), 29635-29647; https://doi.org/10.3390/s151129635
Received: 3 September 2015 / Revised: 9 November 2015 / Accepted: 19 November 2015 / Published: 24 November 2015
Cited by 10 | Viewed by 2103 | PDF Full-text (1681 KB) | HTML Full-text | XML Full-text
Abstract
Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans [...] Read more.
Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle
Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors
Sensors 2015, 15(11), 29618-29634; https://doi.org/10.3390/s151129618
Received: 4 September 2015 / Revised: 16 November 2015 / Accepted: 18 November 2015 / Published: 24 November 2015
Cited by 5 | Viewed by 2121 | PDF Full-text (2793 KB) | HTML Full-text | XML Full-text
Abstract
A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops of a concentrated aqueous ammonium nitrate solution from a drop-on-demand [...] Read more.
A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops of a concentrated aqueous ammonium nitrate solution from a drop-on-demand (DOD) inkjet printer at specific locations on a silicon substrate rendered hydrophobic by a perfluorodecytrichlorosilane monolayer coating. The deposited liquid droplets form into the shape of a spherical shaped cap; during the evaporation process, a deposited liquid droplet maintains this geometry until it forms a solid micrometer sized particle. Arrays of solid particles are obtained by sequential translation of the printer stage. The use of DOD inkjet printing for fabrication of discrete particle arrays allows for precise control of particle characteristics (mass, diameter and height), as well as the particle number and spatial distribution on the substrate. The final mass of an individual particle is precisely determined by using gravimetric measurement of the average mass of solution ejected per microdrop. The primary application of this method is fabrication of test materials for the evaluation of spatially-resolved optical and mass spectrometry based sensors used for detecting particle residues of contraband materials, such as explosives or narcotics. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Vision Sensor-Based Road Detection for Field Robot Navigation
Sensors 2015, 15(11), 29594-29617; https://doi.org/10.3390/s151129594
Received: 21 September 2015 / Revised: 13 November 2015 / Accepted: 17 November 2015 / Published: 24 November 2015
Cited by 11 | Viewed by 2578 | PDF Full-text (38257 KB) | HTML Full-text | XML Full-text
Abstract
Road detection is an essential component of field robot navigation systems. Vision sensors play an important role in road detection for their great potential in environmental perception. In this paper, we propose a hierarchical vision sensor-based method for robust road detection in challenging [...] Read more.
Road detection is an essential component of field robot navigation systems. Vision sensors play an important role in road detection for their great potential in environmental perception. In this paper, we propose a hierarchical vision sensor-based method for robust road detection in challenging road scenes. More specifically, for a given road image captured by an on-board vision sensor, we introduce a multiple population genetic algorithm (MPGA)-based approach for efficient road vanishing point detection. Superpixel-level seeds are then selected in an unsupervised way using a clustering strategy. Then, according to the GrowCut framework, the seeds proliferate and iteratively try to occupy their neighbors. After convergence, the initial road segment is obtained. Finally, in order to achieve a globally-consistent road segment, the initial road segment is refined using the conditional random field (CRF) framework, which integrates high-level information into road detection. We perform several experiments to evaluate the common performance, scale sensitivity and noise sensitivity of the proposed method. The experimental results demonstrate that the proposed method exhibits high robustness compared to the state of the art. Full article
(This article belongs to the Special Issue Sensors for Robots)
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Open AccessArticle
Automated Low-Cost Smartphone-Based Lateral Flow Saliva Test Reader for Drugs-of-Abuse Detection
Sensors 2015, 15(11), 29569-29593; https://doi.org/10.3390/s151129569
Received: 31 August 2015 / Revised: 10 November 2015 / Accepted: 16 November 2015 / Published: 24 November 2015
Cited by 31 | Viewed by 3277 | PDF Full-text (5228 KB) | HTML Full-text | XML Full-text
Abstract
Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. [...] Read more.
Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. While automated test readers providing a result-consistent solution are widely available, they usually lack portability. In this paper, we present a smartphone-based automated reader for drug-of-abuse lateral flow assay tests, consisting of an inexpensive light box and a smartphone device. Test images captured with the smartphone camera are processed in the device using computer vision and machine learning techniques to perform automatic extraction of the results. A deep validation of the system has been carried out showing the high accuracy of the system. The proposed approach, applicable to any line-based or color-based lateral flow test in the market, effectively reduces the manufacturing costs of the reader and makes it portable and massively available while providing accurate, reliable results. Full article
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Open AccessArticle
Automated Negotiation for Resource Assignment in Wireless Surveillance Sensor Networks
Sensors 2015, 15(11), 29547-29568; https://doi.org/10.3390/s151129547
Received: 23 September 2015 / Revised: 6 November 2015 / Accepted: 18 November 2015 / Published: 24 November 2015
Cited by 10 | Viewed by 2376 | PDF Full-text (412 KB) | HTML Full-text | XML Full-text
Abstract
Due to the low cost of CMOS IP-based cameras, wireless surveillance sensor networks have emerged as a new application of sensor networks able to monitor public or private areas or even country borders. Since these networks are bandwidth intensive and the radioelectric spectrum [...] Read more.
Due to the low cost of CMOS IP-based cameras, wireless surveillance sensor networks have emerged as a new application of sensor networks able to monitor public or private areas or even country borders. Since these networks are bandwidth intensive and the radioelectric spectrum is limited, especially in unlicensed bands, it is mandatory to assign frequency channels in a smart manner. In this work, we propose the application of automated negotiation techniques for frequency assignment. Results show that these techniques are very suitable for the problem, being able to obtain the best solutions among the techniques with which we have compared them. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle
A Real-Time Monitoring System of Industry Carbon Monoxide Based on Wireless Sensor Networks
Sensors 2015, 15(11), 29535-29546; https://doi.org/10.3390/s151129535
Received: 30 July 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 86 | Viewed by 3573 | PDF Full-text (3042 KB) | HTML Full-text | XML Full-text
Abstract
Carbon monoxide (CO) burns or explodes at over-standard concentration. Hence, in this paper, a Wifi-based, real-time monitoring of a CO system is proposed for application in the construction industry, in which a sensor measuring node is designed by low-frequency modulation method to acquire [...] Read more.
Carbon monoxide (CO) burns or explodes at over-standard concentration. Hence, in this paper, a Wifi-based, real-time monitoring of a CO system is proposed for application in the construction industry, in which a sensor measuring node is designed by low-frequency modulation method to acquire CO concentration reliably, and a digital filtering method is adopted for noise filtering. According to the triangulation, the Wifi network is constructed to transmit information and determine the position of nodes. The measured data are displayed on a computer or smart phone by a graphical interface. The experiment shows that the monitoring system obtains excellent accuracy and stability in long-term continuous monitoring. Full article
(This article belongs to the Special Issue Sensors for Fire Detection)
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Open AccessArticle
Detection of Lettuce Discoloration Using Hyperspectral Reflectance Imaging
Sensors 2015, 15(11), 29511-29534; https://doi.org/10.3390/s151129511
Received: 10 July 2015 / Revised: 11 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 5 | Viewed by 2417 | PDF Full-text (2931 KB) | HTML Full-text | XML Full-text
Abstract
Rapid visible/near-infrared (VNIR) hyperspectral imaging methods, employing both a single waveband algorithm and multi-spectral algorithms, were developed in order to discrimination between sound and discolored lettuce. Reflectance spectra for sound and discolored lettuce surfaces were extracted from hyperspectral reflectance images obtained in the [...] Read more.
Rapid visible/near-infrared (VNIR) hyperspectral imaging methods, employing both a single waveband algorithm and multi-spectral algorithms, were developed in order to discrimination between sound and discolored lettuce. Reflectance spectra for sound and discolored lettuce surfaces were extracted from hyperspectral reflectance images obtained in the 400–1000 nm wavelength range. The optimal wavebands for discriminating between discolored and sound lettuce surfaces were determined using one-way analysis of variance. Multi-spectral imaging algorithms developed using ratio and subtraction functions resulted in enhanced classification accuracy of above 99.9% for discolored and sound areas on both adaxial and abaxial lettuce surfaces. Ratio imaging (RI) and subtraction imaging (SI) algorithms at wavelengths of 552/701 nm and 557–701 nm, respectively, exhibited better classification performances compared to results obtained for all possible two-waveband combinations. These results suggest that hyperspectral reflectance imaging techniques can potentially be used to discriminate between discolored and sound fresh-cut lettuce. Full article
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Open AccessArticle
TF4SM: A Framework for Developing Traceability Solutions in Small Manufacturing Companies
Sensors 2015, 15(11), 29478-29510; https://doi.org/10.3390/s151129478
Received: 20 July 2015 / Revised: 26 October 2015 / Accepted: 18 November 2015 / Published: 20 November 2015
Cited by 20 | Viewed by 2220 | PDF Full-text (1324 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, manufacturing processes have become highly complex. Besides, more and more, governmental institutions require companies to implement systems to trace a product’s life (especially for foods, clinical materials or similar items). In this paper, we propose a new framework, based on cyber-physical systems, [...] Read more.
Nowadays, manufacturing processes have become highly complex. Besides, more and more, governmental institutions require companies to implement systems to trace a product’s life (especially for foods, clinical materials or similar items). In this paper, we propose a new framework, based on cyber-physical systems, for developing traceability systems in small manufacturing companies (which because of their size cannot implement other commercial products). We propose a general theoretical framework, study the requirements of these companies in relation to traceability systems, propose a reference architecture based on both previous elements and build the first minimum functional prototype, to compare our solution to a traditional tag-based traceability system. Results show that our system reduces the number of inefficiencies and reaction time. Full article
(This article belongs to the Special Issue Cyber-Physical Systems)
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Open AccessArticle
Wireless Low-Power Integrated Basal-Body-Temperature Detection Systems Using Teeth Antennas in the MedRadio Band
Sensors 2015, 15(11), 29467-29477; https://doi.org/10.3390/s151129467
Received: 15 July 2015 / Revised: 10 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 1 | Viewed by 1972 | PDF Full-text (1983 KB) | HTML Full-text | XML Full-text
Abstract
This study proposes using wireless low power thermal sensors for basal-body-temperature detection using frequency modulated telemetry devices. A long-term monitoring sensor requires low-power circuits including a sampling circuit and oscillator. Moreover, temperature compensated technologies are necessary because the modulated frequency might have additional [...] Read more.
This study proposes using wireless low power thermal sensors for basal-body-temperature detection using frequency modulated telemetry devices. A long-term monitoring sensor requires low-power circuits including a sampling circuit and oscillator. Moreover, temperature compensated technologies are necessary because the modulated frequency might have additional frequency deviations caused by the varying temperature. The temperature compensated oscillator is composed of a ring oscillator and a controlled-steering current source with temperature compensation, so the output frequency of the oscillator does not drift with temperature variations. The chip is fabricated in a standard Taiwan Semiconductor Manufacturing Company (TSMC) 0.18-μm complementary metal oxide semiconductor (CMOS) process, and the chip area is 0.9 mm2. The power consumption of the sampling amplifier is 128 µW. The power consumption of the voltage controlled oscillator (VCO) core is less than 40 µW, and the output is −3.04 dBm with a buffer stage. The output voltage of the bandgap reference circuit is 1 V. For temperature measurements, the maximum error is 0.18 °C with a standard deviation of ±0.061 °C, which is superior to the required specification of 0.1 °C. Full article
(This article belongs to the Special Issue Power Schemes for Biosensors and Biomedical Devices)
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Open AccessArticle
Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation
Sensors 2015, 15(11), 29452-29466; https://doi.org/10.3390/s151129452
Received: 19 October 2015 / Revised: 16 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 7 | Viewed by 2008 | PDF Full-text (863 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates [...] Read more.
This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq) of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Study on Miniaturized UHF Antennas for Partial Discharge Detection in High-Voltage Electrical Equipment
Sensors 2015, 15(11), 29434-29451; https://doi.org/10.3390/s151129434
Received: 18 August 2015 / Revised: 3 November 2015 / Accepted: 10 November 2015 / Published: 20 November 2015
Cited by 16 | Viewed by 2908 | PDF Full-text (2559 KB) | HTML Full-text | XML Full-text
Abstract
Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular [...] Read more.
Detecting partial discharge (PD) is an effective way to evaluate the condition of high-voltage electrical equipment insulation. The UHF detection method has attracted attention due to its high sensitivity, strong interference resistance, and ability to locate PDs. In this paper, a miniaturized equiangular spiral antenna (ESA) for UHF detection that uses a printed circuit board is proposed. I-shaped, L-shaped, and C-shaped microstrip baluns were designed to match the impedance between the ESA and coaxial cable and were verified by a vector network analyzer. For comparison, three other types of UHF antenna were also designed: A microstrip patch antenna, a microstrip slot antenna, and a printed dipole antenna. Their antenna factors were calibrated in a uniform electric field of different frequencies modulated in a gigahertz transverse electromagnetic cell. We performed comparison experiments on PD signal detection using an artificial defect model based on the international IEC 60270 standard. We also conducted time-delay test experiments on the ESA sensor to locate a PD source. It was found that the proposed ESA sensor meets PD signal detection requirements. The sensor’s compact size makes it suitable for internal installation in high-voltage electrical equipment. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications
Sensors 2015, 15(11), 29419-29433; https://doi.org/10.3390/s151129419
Received: 19 August 2015 / Revised: 21 October 2015 / Accepted: 13 November 2015 / Published: 20 November 2015
Cited by 10 | Viewed by 2220 | PDF Full-text (3140 KB) | HTML Full-text | XML Full-text
Abstract
NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to [...] Read more.
NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties of the biosensor. The finally prepared biosensor showed favorable electrocatalytic effects toward hydroquinone. The detection limit was 90 nM (S/N = 3), the sensitivity was 1.5 µA µM−1, the detection linear range was 4 × 10−7–2.37 × 10−6 M. In addition, this biosensor exhibited satisfactory repeatability, reproducibility, anti-interference properties and stability. Besides, the sensor achieved the detection of hydroquinone in lake water. Full article
(This article belongs to the Special Issue Microbial and Enzymatic Biosensors)
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Open AccessArticle
Liver Cancer Detection by a Simple, Inexpensive and Effective Immunosensor with Zinc Oxide Nanoparticles
Sensors 2015, 15(11), 29408-29418; https://doi.org/10.3390/s151129408
Received: 23 September 2015 / Revised: 9 November 2015 / Accepted: 13 November 2015 / Published: 20 November 2015
Cited by 2 | Viewed by 1968 | PDF Full-text (1020 KB) | HTML Full-text | XML Full-text
Abstract
Regular monitoring of blood α-fetoprotein (AFP) and/or carcino-embryonic antigen (CEA) levels is important for the routine screening of liver cancer. However, AFP and CEA have a much lower specificity than des-γ-carboxyprothrombin (DCP) to detect liver cancer. Therefore, the study reported here was designed, [...] Read more.
Regular monitoring of blood α-fetoprotein (AFP) and/or carcino-embryonic antigen (CEA) levels is important for the routine screening of liver cancer. However, AFP and CEA have a much lower specificity than des-γ-carboxyprothrombin (DCP) to detect liver cancer. Therefore, the study reported here was designed, to develop a screen-printed DCP immunosensor incorporating zinc oxide nanoparticles, for accurate determination of DCP. The designed immunosensor shows low detection limits for the detection of DCP: 0.440 ng/mL (based on impedance measurement), 0.081 ng/mL (based on real part of impedance measurement) and 0.078 ng/mL (based on imaginary part of impedance measurement), within the range of 3.125 ng/mL to 2000 ng/mL. In addition, there was little interference to DCP determination by molecules such as Na+, K+, Ca2+, Cl, glucose, urea, and uric acid. It is therefore concluded that the DCP immunosensor developed and reported here is simple, inexpensive and effective, and shows promise in the rapid screening of early-stage liver cancer at home with a point-of-care approach. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle
Feature Selection and Predictors of Falls with Foot Force Sensors Using KNN-Based Algorithms
Sensors 2015, 15(11), 29393-29407; https://doi.org/10.3390/s151129393
Received: 25 September 2015 / Revised: 4 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 10 | Viewed by 2509 | PDF Full-text (806 KB) | HTML Full-text | XML Full-text
Abstract
The aging process may lead to the degradation of lower extremity function in the elderly population, which can restrict their daily quality of life and gradually increase the fall risk. We aimed to determine whether objective measures of physical function could predict subsequent [...] Read more.
The aging process may lead to the degradation of lower extremity function in the elderly population, which can restrict their daily quality of life and gradually increase the fall risk. We aimed to determine whether objective measures of physical function could predict subsequent falls. Ground reaction force (GRF) data, which was quantified by sample entropy, was collected by foot force sensors. Thirty eight subjects (23 fallers and 15 non-fallers) participated in functional movement tests, including walking and sit-to-stand (STS). A feature selection algorithm was used to select relevant features to classify the elderly into two groups: at risk and not at risk of falling down, for three KNN-based classifiers: local mean-based k-nearest neighbor (LMKNN), pseudo nearest neighbor (PNN), local mean pseudo nearest neighbor (LMPNN) classification. We compared classification performances, and achieved the best results with LMPNN, with sensitivity, specificity and accuracy all 100%. Moreover, a subset of GRFs was significantly different between the two groups via Wilcoxon rank sum test, which is compatible with the classification results. This method could potentially be used by non-experts to monitor balance and the risk of falling down in the elderly population. Full article
(This article belongs to the collection Sensors for Globalized Healthy Living and Wellbeing)
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Open AccessArticle
Molecular Electronic Angular Motion Transducer Broad Band Self-Noise
Sensors 2015, 15(11), 29378-29392; https://doi.org/10.3390/s151129378
Received: 17 September 2015 / Revised: 10 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 17 | Viewed by 1903 | PDF Full-text (1626 KB) | HTML Full-text | XML Full-text
Abstract
Modern molecular electronic transfer (MET) angular motion sensors combine high technical characteristics with low cost. Self-noise is one of the key characteristics which determine applications for MET sensors. However, until the present there has not been a model describing the sensor noise in [...] Read more.
Modern molecular electronic transfer (MET) angular motion sensors combine high technical characteristics with low cost. Self-noise is one of the key characteristics which determine applications for MET sensors. However, until the present there has not been a model describing the sensor noise in the complete operating frequency range. The present work reports the results of an experimental study of the self-noise level of such sensors in the frequency range of 0.01–200 Hz. Based on the experimental data, a theoretical model is developed. According to the model, self-noise is conditioned by thermal hydrodynamic fluctuations of the operating fluid flow in the frequency range of 0.01–2 Hz. At the frequency range of 2–100 Hz, the noise power spectral density has a specific inversely proportional dependence of the power spectral density on the frequency that could be attributed to convective processes. In the high frequency range of 100–200 Hz, the noise is conditioned by the voltage noise of the electronics module input stage operational amplifiers and is heavily reliant to the sensor electrical impedance. The presented results allow a deeper understanding of the molecular electronic sensor noise nature to suggest the ways to reduce it. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Early Fault Diagnosis of Bearings Using an Improved Spectral Kurtosis by Maximum Correlated Kurtosis Deconvolution
Sensors 2015, 15(11), 29363-29377; https://doi.org/10.3390/s151129363
Received: 8 September 2015 / Revised: 10 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 41 | Viewed by 2240 | PDF Full-text (1349 KB) | HTML Full-text | XML Full-text
Abstract
The early fault characteristics of rolling element bearings carried by vibration signals are quite weak because the signals are generally masked by heavy background noise. To extract the weak fault characteristics of bearings from the signals, an improved spectral kurtosis (SK) method is [...] Read more.
The early fault characteristics of rolling element bearings carried by vibration signals are quite weak because the signals are generally masked by heavy background noise. To extract the weak fault characteristics of bearings from the signals, an improved spectral kurtosis (SK) method is proposed based on maximum correlated kurtosis deconvolution (MCKD). The proposed method combines the ability of MCKD in indicating the periodic fault transients and the ability of SK in locating these transients in the frequency domain. A simulation signal overwhelmed by heavy noise is used to demonstrate the effectiveness of the proposed method. The results show that MCKD is beneficial to clarify the periodic impulse components of the bearing signals, and the method is able to detect the resonant frequency band of the signal and extract its fault characteristic frequency. Through analyzing actual vibration signals collected from wind turbines and hot strip rolling mills, we confirm that by using the proposed method, it is possible to extract fault characteristics and diagnose early faults of rolling element bearings. Based on the comparisons with the SK method, it is verified that the proposed method is more suitable to diagnose early faults of rolling element bearings. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
An Analytic Model for the Success Rate of a Robotic Actuator System in Hitting Random Targets
Sensors 2015, 15(11), 29346-29362; https://doi.org/10.3390/s151129346
Received: 5 September 2015 / Revised: 10 November 2015 / Accepted: 17 November 2015 / Published: 20 November 2015
Cited by 1 | Viewed by 1311 | PDF Full-text (3131 KB) | HTML Full-text | XML Full-text
Abstract
Autonomous robotic systems are increasingly being used in a wide range of applications such as precision agriculture, medicine, and the military. These systems have common features which often includes an action by an “actuator” interacting with a target. While simulations and measurements exist [...] Read more.
Autonomous robotic systems are increasingly being used in a wide range of applications such as precision agriculture, medicine, and the military. These systems have common features which often includes an action by an “actuator” interacting with a target. While simulations and measurements exist for the success rate of hitting targets by some systems, there is a dearth of analytic models which can give insight into, and guidance on optimization, of new robotic systems. The present paper develops a simple model for estimation of the success rate for hitting random targets from a moving platform. The model has two main dimensionless parameters: the ratio of actuator spacing to target diameter; and the ratio of platform distance moved (between actuator “firings”) to the target diameter. It is found that regions of parameter space having specified high success are described by simple equations, providing guidance on design. The role of a “cost function” is introduced which, when minimized, provides optimization of design, operating, and risk mitigation costs. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle
Multi-Layer Approach for the Detection of Selective Forwarding Attacks
Sensors 2015, 15(11), 29332-29345; https://doi.org/10.3390/s151129332
Received: 22 September 2015 / Revised: 13 November 2015 / Accepted: 16 November 2015 / Published: 19 November 2015
Cited by 4 | Viewed by 1778 | PDF Full-text (1333 KB) | HTML Full-text | XML Full-text
Abstract
Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities [...] Read more.
Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD). The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable. Full article
(This article belongs to the Special Issue Security and Privacy in Sensor Networks)
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Open AccessArticle
Pothole Detection System Using a Black-box Camera
Sensors 2015, 15(11), 29316-29331; https://doi.org/10.3390/s151129316
Received: 30 September 2015 / Revised: 16 November 2015 / Accepted: 17 November 2015 / Published: 19 November 2015
Cited by 20 | Viewed by 4298 | PDF Full-text (2736 KB) | HTML Full-text | XML Full-text
Abstract
Aging roads and poor road-maintenance systems result a large number of potholes, whose numbers increase over time. Potholes jeopardize road safety and transportation efficiency. Moreover, they are often a contributing factor to car accidents. To address the problems associated with potholes, the locations [...] Read more.
Aging roads and poor road-maintenance systems result a large number of potholes, whose numbers increase over time. Potholes jeopardize road safety and transportation efficiency. Moreover, they are often a contributing factor to car accidents. To address the problems associated with potholes, the locations and size of potholes must be determined quickly. Sophisticated road-maintenance strategies can be developed using a pothole database, which requires a specific pothole-detection system that can collect pothole information at low cost and over a wide area. However, pothole repair has long relied on manual detection efforts. Recent automatic detection systems, such as those based on vibrations or laser scanning, are insufficient to detect potholes correctly and inexpensively owing to the unstable detection of vibration-based methods and high costs of laser scanning-based methods. Thus, in this paper, we introduce a new pothole-detection system using a commercial black-box camera. The proposed system detects potholes over a wide area and at low cost. We have developed a novel pothole-detection algorithm specifically designed to work with the embedded computing environments of black-box cameras. Experimental results are presented with our proposed system, showing that potholes can be detected accurately in real-time. Full article
(This article belongs to the Special Issue Sensors in New Road Vehicles)
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Open AccessArticle
Concept Design for a 1-Lead Wearable/Implantable ECG Front-End: Power Management
Sensors 2015, 15(11), 29297-29315; https://doi.org/10.3390/s151129297
Received: 15 July 2015 / Revised: 9 November 2015 / Accepted: 13 November 2015 / Published: 19 November 2015
Cited by 2 | Viewed by 1966 | PDF Full-text (2266 KB) | HTML Full-text | XML Full-text
Abstract
Power supply quality and stability are critical for wearable and implantable biomedical applications. For this reason we have designed a reconfigurable switched-capacitor DC-DC converter that, aside from having an extremely small footprint (with an active on-chip area of only 0.04 mm2), [...] Read more.
Power supply quality and stability are critical for wearable and implantable biomedical applications. For this reason we have designed a reconfigurable switched-capacitor DC-DC converter that, aside from having an extremely small footprint (with an active on-chip area of only 0.04 mm2), uses a novel output voltage control method based upon a combination of adaptive gain and discrete frequency scaling control schemes. This novel DC-DC converter achieves a measured output voltage range of 1.0 to 2.2 V with power delivery up to 7.5 mW with 75% efficiency. In this paper, we present the use of this converter as a power supply for a concept design of a wearable (15 mm × 15 mm) 1-lead ECG front-end sensor device that simultaneously harvests power and communicates with external receivers when exposed to a suitable RF field. Due to voltage range limitations of the fabrication process of the current prototype chip, we focus our analysis solely on the power supply of the ECG front-end whose design is also detailed in this paper. Measurement results show not just that the power supplied is regulated, clean and does not infringe upon the ECG bandwidth, but that there is negligible difference between signals acquired using standard linear power-supplies and when the power is regulated by our power management chip. Full article
(This article belongs to the Special Issue Power Schemes for Biosensors and Biomedical Devices)
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Open AccessArticle
A Wireless Sensor Network-Based Approach with Decision Support for Monitoring Lake Water Quality
Sensors 2015, 15(11), 29273-29296; https://doi.org/10.3390/s151129273
Received: 9 September 2015 / Revised: 8 November 2015 / Accepted: 11 November 2015 / Published: 19 November 2015
Cited by 12 | Viewed by 2514 | PDF Full-text (2252 KB) | HTML Full-text | XML Full-text
Abstract
Online monitoring and water quality analysis of lakes are urgently needed. A feasible and effective approach is to use a Wireless Sensor Network (WSN). Lake water environments, like other real world environments, present many changing and unpredictable situations. To ensure flexibility in such [...] Read more.
Online monitoring and water quality analysis of lakes are urgently needed. A feasible and effective approach is to use a Wireless Sensor Network (WSN). Lake water environments, like other real world environments, present many changing and unpredictable situations. To ensure flexibility in such an environment, the WSN node has to be prepared to deal with varying situations. This paper presents a WSN self-configuration approach for lake water quality monitoring. The approach is based on the integration of a semantic framework, where a reasoner can make decisions on the configuration of WSN services. We present a WSN ontology and the relevant water quality monitoring context information, which considers its suitability in a pervasive computing environment. We also propose a rule-based reasoning engine that is used to conduct decision support through reasoning techniques and context-awareness. To evaluate the approach, we conduct usability experiments and performance benchmarks. Full article
(This article belongs to the Section Sensor Networks)
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Open AccessArticle
A Passive Testing Approach for Protocols in Wireless Sensor Networks
Sensors 2015, 15(11), 29250-29272; https://doi.org/10.3390/s151129250
Received: 12 October 2015 / Revised: 8 November 2015 / Accepted: 13 November 2015 / Published: 19 November 2015
Cited by 1 | Viewed by 1857 | PDF Full-text (1458 KB) | HTML Full-text | XML Full-text
Abstract
Smart systems are today increasingly developed with the number of wireless sensor devices drastically increasing. They are implemented within several contexts throughout our environment. Thus, sensed data transported in ubiquitous systems are important, and the way to carry them must be efficient and [...] Read more.
Smart systems are today increasingly developed with the number of wireless sensor devices drastically increasing. They are implemented within several contexts throughout our environment. Thus, sensed data transported in ubiquitous systems are important, and the way to carry them must be efficient and reliable. For that purpose, several routing protocols have been proposed for wireless sensor networks (WSN). However, one stage that is often neglected before their deployment is the conformance testing process, a crucial and challenging step. Compared to active testing techniques commonly used in wired networks, passive approaches are more suitable to the WSN environment. While some works propose to specify the protocol with state models or to analyze them with simulators and emulators, we here propose a logic-based approach for formally specifying some functional requirements of a novel WSN routing protocol. We provide an algorithm to evaluate these properties on collected protocol execution traces. Further, we demonstrate the efficiency and suitability of our approach by its application into common WSN functional properties, as well as specific ones designed from our own routing protocol. We provide relevant testing verdicts through a real indoor testbed and the implementation of our protocol. Furthermore, the flexibility, genericity and practicability of our approach have been proven by the experimental results. Full article
(This article belongs to the Special Issue Identification, Information & Knowledge in the Internet of Things)
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Open AccessArticle
An Electrochemical Quartz Crystal Microbalance Multisensor System Based on Phthalocyanine Nanostructured Films: Discrimination of Musts
Sensors 2015, 15(11), 29233-29249; https://doi.org/10.3390/s151129233
Received: 10 September 2015 / Revised: 9 October 2015 / Accepted: 13 November 2015 / Published: 19 November 2015
Cited by 5 | Viewed by 1915 | PDF Full-text (1391 KB) | HTML Full-text | XML Full-text
Abstract
An array of electrochemical quartz crystal electrodes (EQCM) modified with nanostructured films based on phthalocyanines was developed and used to discriminate musts prepared from different varieties of grapes. Nanostructured films of iron, nickel and copper phthalocyanines were deposited on Pt/quartz crystals through the [...] Read more.
An array of electrochemical quartz crystal electrodes (EQCM) modified with nanostructured films based on phthalocyanines was developed and used to discriminate musts prepared from different varieties of grapes. Nanostructured films of iron, nickel and copper phthalocyanines were deposited on Pt/quartz crystals through the Layer by Layer technique by alternating layers of the corresponding phthalocyanine and poly-allylamine hydrochloride. Simultaneous electrochemical and mass measurements were used to study the mass changes accompanying the oxidation of electroactive species present in must samples obtained from six Spanish varieties of grapes (Juan García, Prieto Picudo, Mencía Regadío, Cabernet Sauvignon, Garnacha and Tempranillo). The mass and voltammetric outputs were processed using three-way models. Parallel Factor Analysis (PARAFAC) was successfully used to discriminate the must samples according to their variety. Multi-way partial least squares (N-PLS) evidenced the correlations existing between the voltammetric data and the polyphenolic content measured by chemical methods. Similarly, N-PLS showed a correlation between mass outputs and parameters related to the sugar content. These results demonstrated that electronic tongues based on arrays of EQCM sensors can offer advantages over arrays of mass or voltammetric sensors used separately. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle
Toward Higher-Order Mass Detection: Influence of an Adsorbate’s Rotational Inertia and Eccentricity on the Resonant Response of a Bernoulli-Euler Cantilever Beam
Sensors 2015, 15(11), 29209-29232; https://doi.org/10.3390/s151129209
Received: 30 September 2015 / Revised: 30 October 2015 / Accepted: 11 November 2015 / Published: 19 November 2015
Cited by 5 | Viewed by 2644 | PDF Full-text (3186 KB) | HTML Full-text | XML Full-text
Abstract
In this paper a new theoretical model is derived, the results of which permit a detailed examination of how the resonant characteristics of a cantilever are influenced by a particle (adsorbate) attached at an arbitrary position along the beam’s length. Unlike most previous [...] Read more.
In this paper a new theoretical model is derived, the results of which permit a detailed examination of how the resonant characteristics of a cantilever are influenced by a particle (adsorbate) attached at an arbitrary position along the beam’s length. Unlike most previous work, the particle need not be small in mass or dimension relative to the beam, and the adsorbate’s geometric characteristics are incorporated into the model via its rotational inertia and eccentricity relative to the beam axis. For the special case in which the adsorbate’s (translational) mass is indeed small, an analytical solution is obtained for the particle-induced resonant frequency shift of an arbitrary flexural mode, including the effects of rotational inertia and eccentricity. This solution is shown to possess the exact first-order behavior in the normalized particle mass and represents a generalization of analytical solutions derived by others in earlier studies. The results suggest the potential for “higher-order” nanobeam-based mass detection methods by which the multi-mode frequency response reflects not only the adsorbate’s mass but also important geometric data related to its size, shape, or orientation (i.e., the mass distribution), thus resulting in more highly discriminatory techniques for discrete-mass sensing. Full article
(This article belongs to the Special Issue Nanomechanics for Sensing and Spectrometry)
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