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Sensors, Volume 14, Issue 7 (July 2014), Pages 11278-13307

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Open AccessArticle Enhanced Response of a Proteinase K-Based Conductometric Biosensor Using Nanoparticles
Sensors 2014, 14(7), 13298-13307; https://doi.org/10.3390/s140713298
Received: 7 April 2014 / Revised: 17 June 2014 / Accepted: 17 July 2014 / Published: 23 July 2014
Cited by 4 | PDF Full-text (308 KB) | HTML Full-text | XML Full-text
Abstract
Proteinases are involved in a multitude of important physiological processes, such as protein metabolism. For this reason, a conductometric enzyme biosensor based on proteinase K was developed using two types of nanoparticles (gold and magnetic). The enzyme was directly adsorbed on negatively charged
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Proteinases are involved in a multitude of important physiological processes, such as protein metabolism. For this reason, a conductometric enzyme biosensor based on proteinase K was developed using two types of nanoparticles (gold and magnetic). The enzyme was directly adsorbed on negatively charged nanoparticles and then deposited and cross-linked on a planar interdigitated electrode (IDE). The biosensor was characterized with bovine serum albumin (BSA) as a standard protein. Higher sensitivity was obtained using gold nanoparticles. The linear range for BSA determination was then from 0.5 to 10 mg/L with a maximum response of 154 µs. These results are greater than that found without any nanoparticles (maximum response of 10 µs). The limit of detection (LOD) was 0.3 mg/L. An inter-sensor reproducibility of 3.5% was obtained. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Strategy for Making a Superior Quenchbody to Proteins: Effect of the Fluorophore Position
Sensors 2014, 14(7), 13285-13297; https://doi.org/10.3390/s140713285
Received: 27 May 2014 / Revised: 3 July 2014 / Accepted: 16 July 2014 / Published: 23 July 2014
Cited by 6 | PDF Full-text (3562 KB) | HTML Full-text | XML Full-text
Abstract
Antibody-based sensors have made outstanding contributions to the fields of molecular biology and biotechnology. Our group recently developed a novel powerful fluorescent immunosensor strategy named Quenchbody (Q-body), which has been applied to the detection of a range of antigens in a rapid, simple,
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Antibody-based sensors have made outstanding contributions to the fields of molecular biology and biotechnology. Our group recently developed a novel powerful fluorescent immunosensor strategy named Quenchbody (Q-body), which has been applied to the detection of a range of antigens in a rapid, simple, and sensitive manner. However, there were some Q-bodies whose fluorescence response was limited, especially for detecting protein antigens. With the aim of improving this issue, here we made twelve types of Q-bodies incorporated with different number and position of TAMRA fluorophore in the single chain Fv of HyHEL-10, an anti-hen egg lysozyme antibody, as a model. By measuring the fluorescence intensity and its antigen dependency, it was revealed that VL-VH type Q-bodies labeled at a non-CDR loop region of the VL shows the highest fluorescence response. This position locates close to the quenching Trp35 in VL, while it is far from Trp residues in the bound antigen. This result clearly suggests the importance of dye position to maximize the fluorescence quenching and antigen-dependent de-quenching. The discovery may open a way to make many other Q-bodies with superior response. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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Open AccessArticle The Optical Property of Core-Shell Nanosensors and Detection of Atrazine Based on Localized Surface Plasmon Resonance (LSPR) Sensing
Sensors 2014, 14(7), 13273-13284; https://doi.org/10.3390/s140713273
Received: 22 April 2014 / Revised: 17 June 2014 / Accepted: 17 July 2014 / Published: 23 July 2014
Cited by 5 | PDF Full-text (1428 KB) | HTML Full-text | XML Full-text
Abstract
Three different nanosensors with core-shell structures were fabricated by molecular self-assembly and evaporation techniques. Such closely packed nanoparticles exhibit fine optical properties which are useful for biochemical sensing. The refractive index sensitivity (RIS) of nanosensors was detected by varying the refractive index of
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Three different nanosensors with core-shell structures were fabricated by molecular self-assembly and evaporation techniques. Such closely packed nanoparticles exhibit fine optical properties which are useful for biochemical sensing. The refractive index sensitivity (RIS) of nanosensors was detected by varying the refractive index of the surrounding medium and the decay length of nanosensors was investigated using a layer-by-layer polyelectrolyte multilayer assembly. The results showed that the thickness of the Au shell plays an important role in determining the RIS and the decay length. A system based on localized surface plasmon resonances (LSPR) sensing was constructed in our study. The core-shell nanosensors can detect 10 ng/mL atrazine solutions and are suitable for pesticide residue detection. Full article
(This article belongs to the Special Issue Nanoparticle-Based Biosensors)
Open AccessArticle Detecting Cannabis Use on the Human Skin Surface via an Electronic Nose System
Sensors 2014, 14(7), 13256-13272; https://doi.org/10.3390/s140713256
Received: 9 April 2014 / Revised: 17 June 2014 / Accepted: 17 July 2014 / Published: 23 July 2014
Cited by 7 | PDF Full-text (3871 KB) | HTML Full-text | XML Full-text
Abstract
The most commonly used drug testing methods are based on the analysis of hair and urine using gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry or immunoassay screening. These methods are time-consuming and partly expensive. One alternative method could be the application of an “electronic
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The most commonly used drug testing methods are based on the analysis of hair and urine using gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry or immunoassay screening. These methods are time-consuming and partly expensive. One alternative method could be the application of an “electronic nose” (eNose). We have developed an eNose to detect directly on the human skin surface metabolic changes in the human body odor caused by cannabis consumption. Twenty cannabis-smoking and 20 tobacco-smoking volunteers were enrolled in this study. For the sensor signal data processing, two different methods were applied: Principle component analysis (PCA) with discriminant analysis, and the method of pattern recognition with subsequent support vector machines (SVM) processing. The PCA analysis achieved a correct classification of 70%, whereas the SVM obtained an accuracy of 92.5% (sensitivity 95%, specificity 90%) between cannabis-consuming volunteers and tobacco-smoking subjects. This study shows evidence that a low-cost, portable and fast-working eNose system could be useful for health protection, security agencies and for forensic investigations. The ability to analyze human body odor with an eNose opens up a wide field for diagnosing other drugs and also various diseases. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach
Sensors 2014, 14(7), 13243-13255; https://doi.org/10.3390/s140713243
Received: 22 July 2013 / Revised: 3 June 2014 / Accepted: 18 June 2014 / Published: 23 July 2014
Cited by 2 | PDF Full-text (3110 KB) | HTML Full-text | XML Full-text
Abstract
Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the
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Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep) soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Small Infrared Target Detection by Region-Adaptive Clutter Rejection for Sea-Based Infrared Search and Track
Sensors 2014, 14(7), 13210-13242; https://doi.org/10.3390/s140713210
Received: 8 May 2014 / Revised: 24 June 2014 / Accepted: 15 July 2014 / Published: 22 July 2014
Cited by 25 | PDF Full-text (6123 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a region-adaptive clutter rejection method for small target detection in sea-based infrared search and track. In the real world, clutter normally generates many false detections that impede the deployment of such detection systems. Incoming targets (missiles, boats, etc.) can be
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This paper presents a region-adaptive clutter rejection method for small target detection in sea-based infrared search and track. In the real world, clutter normally generates many false detections that impede the deployment of such detection systems. Incoming targets (missiles, boats, etc.) can be located in the sky, horizon and sea regions, which have different types of clutters, such as clouds, a horizontal line and sea-glint. The characteristics of regional clutter were analyzed after the geometrical analysis-based region segmentation. The false detections caused by cloud clutter were removed by the spatial attribute-based classification. Those by the horizontal line were removed using the heterogeneous background removal filter. False alarms by sun-glint were rejected using the temporal consistency filter, which is the most difficult part. The experimental results of the various cluttered background sequences show that the proposed region adaptive clutter rejection method produces fewer false alarms than that of the mean subtraction filter (MSF) with an acceptable degradation detection rate. Full article
Open AccessArticle A Large Response Range Reflectometric Urea Biosensor Made from Silica-Gel Nanoparticles
Sensors 2014, 14(7), 13186-13209; https://doi.org/10.3390/s140713186
Received: 21 December 2013 / Revised: 3 July 2014 / Accepted: 14 July 2014 / Published: 22 July 2014
Cited by 9 | PDF Full-text (961 KB) | HTML Full-text | XML Full-text
Abstract
A new silica-gel nanospheres (SiO2NPs) composition was formulated, followed by biochemical surface functionalization to examine its potential in urea biosensor development. The SiO2NPs were basically synthesized based on sol–gel chemistry using a modified Stober method. The SiO2NPs
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A new silica-gel nanospheres (SiO2NPs) composition was formulated, followed by biochemical surface functionalization to examine its potential in urea biosensor development. The SiO2NPs were basically synthesized based on sol–gel chemistry using a modified Stober method. The SiO2NPs surfaces were modified with amine (-NH2) functional groups for urease immobilization in the presence of glutaric acid (GA) cross-linker. The chromoionophore pH-sensitive dye ETH 5294 was physically adsorbed on the functionalized SiO2NPs as pH transducer. The immobilized urease determined urea concentration reflectometrically based on the colour change of the immobilized chromoionophore as a result of the enzymatic hydrolysis of urea. The pH changes on the biosensor due to the catalytic enzyme reaction of immobilized urease were found to correlate with the urea concentrations over a linear response range of 50–500 mM (R2 = 0.96) with a detection limit of 10 mM urea. The biosensor response time was 9 min with reproducibility of less than 10% relative standard deviation (RSD). This optical urea biosensor did not show interferences by Na+, K+, Mg2+ and NH4+ ions. The biosensor performance has been validated using urine samples in comparison with a non-enzymatic method based on the use of p-dimethylaminobenzaldehyde (DMAB) reagent and demonstrated a good correlation between the two different methods (R2 = 0.996 and regression slope of 1.0307). The SiO2NPs-based reflectometric urea biosensor showed improved dynamic linear response range when compared to other nanoparticle-based optical urea biosensors. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Bio-Inspired Micro-Fluidic Angular-Rate Sensor for Vestibular Prostheses
Sensors 2014, 14(7), 13173-13185; https://doi.org/10.3390/s140713173
Received: 16 June 2014 / Revised: 1 July 2014 / Accepted: 9 July 2014 / Published: 22 July 2014
Cited by 5 | PDF Full-text (2281 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an alternative approach for angular-rate sensing based on the way that the natural vestibular semicircular canals operate, whereby the inertial mass of a fluid is used to deform a sensing structure upon rotation. The presented gyro has been fabricated in
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This paper presents an alternative approach for angular-rate sensing based on the way that the natural vestibular semicircular canals operate, whereby the inertial mass of a fluid is used to deform a sensing structure upon rotation. The presented gyro has been fabricated in a commercially available MEMS process, which allows for microfluidic channels to be implemented in etched glass layers, which sandwich a bulk-micromachined silicon substrate, containing the sensing structures. Measured results obtained from a proof-of-concept device indicate an angular rate sensitivity of less than 1 °/s, which is similar to that of the natural vestibular system. By avoiding the use of a continually-excited vibrating mass, as is practiced in today’s state-of-the-art gyroscopes, an ultra-low power consumption of 300 μW is obtained, thus making it suitable for implantation. Full article
(This article belongs to the Special Issue Implantable Sensors)
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Open AccessCorrection Correction: Deng, F., et al. A CMOS Humidity Sensor for Passive RFID Sensing Applications. Sensors 2014, 14, 8728–8739
Sensors 2014, 14(7), 13171-13172; https://doi.org/10.3390/s140713171
Received: 27 June 2014 / Accepted: 30 June 2014 / Published: 22 July 2014
PDF Full-text (715 KB) | HTML Full-text | XML Full-text
Abstract
The authors wish to make the following corrections to this paper [1]. [...] Full article
(This article belongs to the Special Issue Polymeric Micro Sensors and Actuators)
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Open AccessArticle An Integrated Environment Monitoring System for Underground Coal Mines—Wireless Sensor Network Subsystem with Multi-Parameter Monitoring
Sensors 2014, 14(7), 13149-13170; https://doi.org/10.3390/s140713149
Received: 1 May 2014 / Revised: 9 July 2014 / Accepted: 14 July 2014 / Published: 21 July 2014
Cited by 27 | PDF Full-text (1122 KB) | HTML Full-text | XML Full-text
Abstract
Environment monitoring is important for the safety of underground coal mine production, and it is also an important application of Wireless Sensor Networks (WSNs). We put forward an integrated environment monitoring system for underground coal mine, which uses the existing Cable Monitoring System
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Environment monitoring is important for the safety of underground coal mine production, and it is also an important application of Wireless Sensor Networks (WSNs). We put forward an integrated environment monitoring system for underground coal mine, which uses the existing Cable Monitoring System (CMS) as the main body and the WSN with multi-parameter monitoring as the supplementary technique. As CMS techniques are mature, this paper mainly focuses on the WSN and the interconnection between the WSN and the CMS. In order to implement the WSN for underground coal mines, two work modes are designed: periodic inspection and interrupt service; the relevant supporting technologies, such as routing mechanism, collision avoidance, data aggregation, interconnection with the CMS, etc., are proposed and analyzed. As WSN nodes are limited in energy supply, calculation and processing power, an integrated network management scheme is designed in four aspects, i.e., topology management, location management, energy management and fault management. Experiments were carried out both in a laboratory and in a real underground coal mine. The test results indicate that the proposed integrated environment monitoring system for underground coal mines is feasible and all designs performed well as expected. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle An Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator for Dielectric Sensing Applications
Sensors 2014, 14(7), 13134-13148; https://doi.org/10.3390/s140713134
Received: 29 April 2014 / Revised: 18 June 2014 / Accepted: 3 July 2014 / Published: 21 July 2014
Cited by 22 | PDF Full-text (1219 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements
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This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 × 14 mm2. Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value. Full article
Open AccessArticle Distributed Power-Line Outage Detection Based on Wide Area Measurement System
Sensors 2014, 14(7), 13114-13133; https://doi.org/10.3390/s140713114
Received: 16 April 2014 / Revised: 12 July 2014 / Accepted: 14 July 2014 / Published: 21 July 2014
Cited by 11 | PDF Full-text (1265 KB) | HTML Full-text | XML Full-text
Abstract
In modern power grids, the fast and reliable detection of power-line outages is an important functionality, which prevents cascading failures and facilitates an accurate state estimation to monitor the real-time conditions of the grids. However, most of the existing approaches for outage detection
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In modern power grids, the fast and reliable detection of power-line outages is an important functionality, which prevents cascading failures and facilitates an accurate state estimation to monitor the real-time conditions of the grids. However, most of the existing approaches for outage detection suffer from two drawbacks, namely: (i) high computational complexity; and (ii) relying on a centralized means of implementation. The high computational complexity limits the practical usage of outage detection only for the case of single-line or double-line outages. Meanwhile, the centralized means of implementation raises security and privacy issues. Considering these drawbacks, the present paper proposes a distributed framework, which carries out in-network information processing and only shares estimates on boundaries with the neighboring control areas. This novel framework relies on a convex-relaxed formulation of the line outage detection problem and leverages the alternating direction method of multipliers (ADMM) for its distributed solution. The proposed framework invokes a low computational complexity, requiring only linear and simple matrix-vector operations. We also extend this framework to incorporate the sparse property of the measurement matrix and employ the LSQRalgorithm to enable a warm start, which further accelerates the algorithm. Analysis and simulation tests validate the correctness and effectiveness of the proposed approaches. Full article
(This article belongs to the Special Issue Sensor Computing for Mobile Security and Big Data Analytics)
Open AccessArticle A New Electrochemical Sensor Based on Task-Specific Ionic Liquids-Modified Palm Shell Activated Carbon for the Determination of Mercury in Water Samples
Sensors 2014, 14(7), 13102-13113; https://doi.org/10.3390/s140713102
Received: 19 May 2014 / Revised: 4 July 2014 / Accepted: 7 July 2014 / Published: 21 July 2014
Cited by 9 | PDF Full-text (736 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a potentiometric sensor composed of palm shell activated carbon modified with trioctylmethylammonium thiosalicylate (TOMATS) was used for the potentiometric determination of mercury ions in water samples. The proposed potentiometric sensor has good operating characteristics towards Hg (II), including a relatively
[...] Read more.
In this study, a potentiometric sensor composed of palm shell activated carbon modified with trioctylmethylammonium thiosalicylate (TOMATS) was used for the potentiometric determination of mercury ions in water samples. The proposed potentiometric sensor has good operating characteristics towards Hg (II), including a relatively high selectivity; a Nernstian response to Hg (II) ions in a concentration range of 1.0 × 10−9 to 1.0 × 10−2 M, with a detection limit of 1 × 10−10 M and a slope of 44.08 ± 1.0 mV/decade; and a fast response time (~5 s). No significant changes in electrode potential were observed when the pH was varied over the range of 3–9. Additionally, the proposed electrode was characterized by good selectivity towards Hg (II) and no significant interferences from other cationic or anionic species. Full article
(This article belongs to the Special Issue Ion Selective Electrodes for Bioavailable Ions)
Open AccessArticle An Optical Fibre-Based Sensor for Respiratory Monitoring
Sensors 2014, 14(7), 13088-13101; https://doi.org/10.3390/s140713088
Received: 29 April 2014 / Revised: 29 April 2014 / Accepted: 15 July 2014 / Published: 21 July 2014
Cited by 26 | PDF Full-text (1031 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a textile-based respiratory sensing system is presented. Highly flexible polymeric optical fibres (POFs) that react to applied pressure were integrated into a carrier fabric to form a wearable sensing system. After the evaluation of different optical fibres, different setups were
[...] Read more.
In this paper, a textile-based respiratory sensing system is presented. Highly flexible polymeric optical fibres (POFs) that react to applied pressure were integrated into a carrier fabric to form a wearable sensing system. After the evaluation of different optical fibres, different setups were compared. To demonstrate the feasibility of such a wearable sensor, the setup featuring the best performance was placed on the human torso, and thus it was possible to measure the respiratory rate. Furthermore, we show that such a wearable system enables to keep track of the way of breathing (diaphragmatic, upper costal and mixed) when the sensor is placed at different positions of the torso. A comparison of the results with the output of some commercial respiratory measurements devices confirmed the utility of such a monitoring device. Full article
(This article belongs to the Special Issue Biomedical Sensors and Systems)
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Open AccessArticle Influence of Segmentation of Ring-Shaped NdFeB Magnets with Parallel Magnetization on Cylindrical Actuators
Sensors 2014, 14(7), 13070-13087; https://doi.org/10.3390/s140713070
Received: 4 May 2014 / Revised: 11 July 2014 / Accepted: 11 July 2014 / Published: 21 July 2014
Cited by 1 | PDF Full-text (1100 KB) | HTML Full-text | XML Full-text
Abstract
This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and
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This work analyses the effects of segmentation followed by parallel magnetization of ring-shaped NdFeB permanent magnets used in slotless cylindrical linear actuators. The main purpose of the work is to evaluate the effects of that segmentation on the performance of the actuator and to present a general overview of the influence of parallel magnetization by varying the number of segments and comparing the results with ideal radially magnetized rings. The analysis is first performed by modelling mathematically the radial and circumferential components of magnetization for both radial and parallel magnetizations, followed by an analysis carried out by means of the 3D finite element method. Results obtained from the models are validated by measuring radial and tangential components of magnetic flux distribution in the air gap on a prototype which employs magnet rings with eight segments each with parallel magnetization. The axial force produced by the actuator was also measured and compared with the results obtained from numerical models. Although this analysis focused on a specific topology of cylindrical actuator, the observed effects on the topology could be extended to others in which surface-mounted permanent magnets are employed, including rotating electrical machines. Full article
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