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Sensors, Volume 10, Issue 5 (May 2010), Pages 4180-5293

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Editorial

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Open AccessEditorial Introduction to the Special Issue on “State-of-the-Art Sensor Technology in Japan”
Sensors 2010, 10(5), 4756-4760; doi:10.3390/s100504756
Received: 30 April 2010 / Accepted: 10 May 2010 / Published: 10 May 2010
Cited by 2 | PDF Full-text (109 KB) | HTML Full-text | XML Full-text
Abstract
The combination of sensing technology with information and communication technology (ICT) could serve both as global eyes that monitor the environment for environmental issues, and as local eyes that monitor humans for aging society issues. System technology is also required to form such
[...] Read more.
The combination of sensing technology with information and communication technology (ICT) could serve both as global eyes that monitor the environment for environmental issues, and as local eyes that monitor humans for aging society issues. System technology is also required to form such global and local eyes. This special issue, “State-of-the-Art Sensor Technology in Japan”, contains articles and reviews related to the monitoring of humans and the environment, and the integration of sensor systems. [...] Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
Open AccessEditorial Sensors: New Challenges in Spain
Sensors 2010, 10(5), 5028-5030; doi:10.3390/s100505028
Received: 6 April 2010 / Published: 19 May 2010
PDF Full-text (47 KB) | HTML Full-text | XML Full-text
Abstract
The main goal of this special issue was to explore sensor technology and its applications in Spain. It is well-known that a reciprocal interrelation exists between sensor technology and the demand for solutions to different problems. Indeed, when a new sensor is developed,
[...] Read more.
The main goal of this special issue was to explore sensor technology and its applications in Spain. It is well-known that a reciprocal interrelation exists between sensor technology and the demand for solutions to different problems. Indeed, when a new sensor is developed, it offers a solution to a problem, but also if a problem requires a solution perhaps new sensors or technologies based on existing sensors could be developed. [...] Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)

Research

Jump to: Editorial, Review, Other

Open AccessArticle CMOS-Integrated Film Bulk Acoustic Resonators for Label-Free Biosensing
Sensors 2010, 10(5), 4180-4193; doi:10.3390/s100504180
Received: 28 February 2010 / Revised: 18 March 2010 / Accepted: 4 April 2010 / Published: 27 April 2010
Cited by 29 | PDF Full-text (416 KB) | HTML Full-text | XML Full-text
Abstract
The throughput is an important parameter for label-free biosensors. Acoustic resonators like the quartz crystal microbalance have a low throughput because the number of sensors which can be used at the same time is limited. Here we present an array of 64 CMOS-integrated
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The throughput is an important parameter for label-free biosensors. Acoustic resonators like the quartz crystal microbalance have a low throughput because the number of sensors which can be used at the same time is limited. Here we present an array of 64 CMOS-integrated film bulk acoustic resonators. We compare the performance with surface plasmon resonance and the quartz crystal microbalance and demonstrate the performance of the sensor for multiplexed detection of DNA. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Reliable Fiber Sensor System with Star-Ring-Bus Architecture
Sensors 2010, 10(5), 4194-4205; doi:10.3390/s100504194
Received: 5 January 2010 / Revised: 8 April 2010 / Accepted: 20 April 2010 / Published: 27 April 2010
Cited by 16 | PDF Full-text (357 KB) | HTML Full-text | XML Full-text
Abstract
This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system
[...] Read more.
This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Generating One Biometric Feature from Another: Faces from Fingerprints
Sensors 2010, 10(5), 4206-4237; doi:10.3390/s100504206
Received: 20 January 2010 / Revised: 4 March 2010 / Accepted: 22 March 2010 / Published: 28 April 2010
Cited by 5 | PDF Full-text (1551 KB) | HTML Full-text | XML Full-text
Abstract
This study presents a new approach based on artificial neural networks for generating one biometric feature (faces) from another (only fingerprints). An automatic and intelligent system was designed and developed to analyze the relationships among fingerprints and faces and also to model and
[...] Read more.
This study presents a new approach based on artificial neural networks for generating one biometric feature (faces) from another (only fingerprints). An automatic and intelligent system was designed and developed to analyze the relationships among fingerprints and faces and also to model and to improve the existence of the relationships. The new proposed system is the first study that generates all parts of the face including eyebrows, eyes, nose, mouth, ears and face border from only fingerprints. It is also unique and different from similar studies recently presented in the literature with some superior features. The parameter settings of the system were achieved with the help of Taguchi experimental design technique. The performance and accuracy of the system have been evaluated with 10-fold cross validation technique using qualitative evaluation metrics in addition to the expanded quantitative evaluation metrics. Consequently, the results were presented on the basis of the combination of these objective and subjective metrics for illustrating the qualitative properties of the proposed methods as well as a quantitative evaluation of their performances. Experimental results have shown that one biometric feature can be determined from another. These results have once more indicated that there is a strong relationship between fingerprints and faces. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Development of a Three Dimensional Neural Sensing Device by a Stacking Method
Sensors 2010, 10(5), 4238-4252; doi:10.3390/s100504238
Received: 16 March 2010 / Revised: 16 April 2010 / Accepted: 19 April 2010 / Published: 28 April 2010
Cited by 17 | PDF Full-text (1117 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
This study reports a new stacking method for assembling a 3-D microprobe array. To date, 3-D array structures have usually been assembled with vertical spacers, snap fasteners and a supporting platform. Such methods have achieved 3-D structures but suffer from complex assembly steps,
[...] Read more.
This study reports a new stacking method for assembling a 3-D microprobe array. To date, 3-D array structures have usually been assembled with vertical spacers, snap fasteners and a supporting platform. Such methods have achieved 3-D structures but suffer from complex assembly steps, vertical interconnection for 3-D signal transmission, low structure strength and large implantable opening. By applying the proposed stacking method, the previous techniques could be replaced by 2-D wire bonding. In this way, supporting platforms with slots and vertical spacers were no longer needed. Furthermore, ASIC chips can be substituted for the spacers in the stacked arrays to achieve system integration, design flexibility and volume usage efficiency. To avoid overflow of the adhesive fluid during assembly, an anti-overflow design which made use of capillary action force was applied in the stacking method as well. Moreover, presented stacking procedure consumes only 35 minutes in average for a 4 × 4 3-D microprobe array without requiring other specially made assembly tools. To summarize, the advantages of the proposed stacking method for 3-D array assembly include simplified assembly process, high structure strength, smaller opening area and integration ability with active circuits. This stacking assembly technique allows an alternative method to create 3-D structures from planar components. Full article
(This article belongs to the Special Issue Bio-devices and Materials)
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Open AccessArticle Monitoring of Water Content in Building Materials Using a Wireless Passive Sensor
Sensors 2010, 10(5), 4270-4280; doi:10.3390/s100504270
Received: 27 February 2010 / Revised: 20 March 2010 / Accepted: 6 April 2010 / Published: 28 April 2010
Cited by 20 | PDF Full-text (530 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an innovative design of a wireless, passive LC sensor and its application for monitoring of water content in building materials. The sensor was embedded in test material samples so that the internal water content of the samples could be measured
[...] Read more.
This paper describes an innovative design of a wireless, passive LC sensor and its application for monitoring of water content in building materials. The sensor was embedded in test material samples so that the internal water content of the samples could be measured with an antenna by tracking the changes in the sensor’s resonant frequency. Since the dielectric constant of water was much higher compared with that of the test samples, the presence of water in the samples increased the capacitance of the LC circuit, thus decreasing the sensor’s resonant frequency. The sensor is made up of a printed circuit board in one metal layer and water content has been determined for clay brick and autoclaved aerated concrete block, both widely used construction materials. Measurements were conducted at room temperature using a HP-4194A Impedance/Gain-Phase Analyzer instrument. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Geographic Information System Framework for the Management of Sensor Deployments
Sensors 2010, 10(5), 4281-4295; doi:10.3390/s100504281
Received: 23 February 2010 / Revised: 20 April 2010 / Accepted: 21 April 2010 / Published: 29 April 2010
Cited by 2 | PDF Full-text (467 KB) | HTML Full-text | XML Full-text
Abstract
A prototype Geographic Information System (GIS) framework has been developed to map, manage, and monitor sensors with respect to other geographic features, including land base and in-plant features. The GIS framework supports geographic placement and subsequent discovery, query, and tasking of sensors in
[...] Read more.
A prototype Geographic Information System (GIS) framework has been developed to map, manage, and monitor sensors with respect to other geographic features, including land base and in-plant features. The GIS framework supports geographic placement and subsequent discovery, query, and tasking of sensors in a network-centric environment using Web services. The framework couples the GIS feature placement logic of sensors with an extensible ontology which captures the capabilities, properties, protocols, integrity constraints, and other parameters of interest for a large variety of sensor types. The approach is significant in that custom, GIS-based interfaces can be rapidly developed via the integration of sensors and sensor networks into applications without having detailed knowledge of the sensors’ underlying device drivers by leveraging service-oriented computing infrastructure within the GIS framework. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer
Sensors 2010, 10(5), 4373-4380; doi:10.3390/s100504373
Received: 23 March 2010 / Revised: 23 April 2010 / Accepted: 23 April 2010 / Published: 29 April 2010
Cited by 3 | PDF Full-text (101 KB) | HTML Full-text | XML Full-text
Abstract
In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port
[...] Read more.
In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Untraceable Mobile Node Authentication in WSN
Sensors 2010, 10(5), 4410-4429; doi:10.3390/s100504410
Received: 28 February 2010 / Revised: 20 March 2010 / Accepted: 5 April 2010 / Published: 30 April 2010
Cited by 15 | PDF Full-text (554 KB) | HTML Full-text | XML Full-text
Abstract
Mobility of sensor node in Wireless Sensor Networks (WSN) brings security issues such as re-authentication and tracing the node movement. However, current security researches on WSN are insufficient to support such environments since their designs only considered the static environments. In this paper,
[...] Read more.
Mobility of sensor node in Wireless Sensor Networks (WSN) brings security issues such as re-authentication and tracing the node movement. However, current security researches on WSN are insufficient to support such environments since their designs only considered the static environments. In this paper, we propose the efficient node authentication and key exchange protocol that reduces the overhead in node re-authentication and also provides untraceability of mobile nodes. Compared with previous protocols, our protocol has only a third of communication and computational overhead. We expect our protocol to be the efficient solution that increases the lifetime of sensor network. Full article
Open AccessArticle Common Criteria Related Security Design Patterns—Validation on the Intelligent Sensor Example Designed for Mine Environment
Sensors 2010, 10(5), 4456-4496; doi:10.3390/s100504456
Received: 5 March 2010 / Revised: 15 April 2010 / Accepted: 28 April 2010 / Published: 30 April 2010
Cited by 7 | PDF Full-text (382 KB) | HTML Full-text | XML Full-text
Abstract
The paper discusses the security issues of intelligent sensors that are able to measure and process data and communicate with other information technology (IT) devices or systems. Such sensors are often used in high risk applications. To improve their robustness, the sensor systems
[...] Read more.
The paper discusses the security issues of intelligent sensors that are able to measure and process data and communicate with other information technology (IT) devices or systems. Such sensors are often used in high risk applications. To improve their robustness, the sensor systems should be developed in a restricted way to provide them with assurance. One of assurance creation methodologies is Common Criteria (ISO/IEC 15408), used for IT products and systems. The contribution of the paper is a Common Criteria compliant and pattern-based method for the intelligent sensors security development. The paper concisely presents this method and its evaluation for the sensor detecting methane in a mine, focusing on the security problem of the intelligent sensor definition and solution. The aim of the validation is to evaluate and improve the introduced method. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Adaptive Square-Shaped Trajectory-Based Service Location Protocol in Wireless Sensor Networks
Sensors 2010, 10(5), 4497-4520; doi:10.3390/s100504497
Received: 22 March 2010 / Revised: 8 April 2010 / Accepted: 14 April 2010 / Published: 30 April 2010
PDF Full-text (1111 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we propose an adaptive square-shaped trajectory (ASST)-based service location method to ensure load scalability in wireless sensor networks. This first establishes a square-shaped trajectory over the nodes that surround a target point computed by the hash function and any user
[...] Read more.
In this paper we propose an adaptive square-shaped trajectory (ASST)-based service location method to ensure load scalability in wireless sensor networks. This first establishes a square-shaped trajectory over the nodes that surround a target point computed by the hash function and any user can access it, using the hash. Both the width and the size of the trajectory are dynamically adjustable, depending on the number of queries made to the service information on the trajectory. The number of sensor nodes on the trajectory varies in proportion to the changing trajectory shape, allowing high loads to be distributed around the hot spot area. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Multipath Routing Protocol Based on Clustering and Ant Colony Optimization for Wireless Sensor Networks
Sensors 2010, 10(5), 4521-4540; doi:10.3390/s100504521
Received: 4 March 2010 / Revised: 14 April 2010 / Accepted: 16 April 2010 / Published: 4 May 2010
Cited by 33 | PDF Full-text (321 KB) | HTML Full-text | XML Full-text
Abstract
For monitoring burst events in a kind of reactive wireless sensor networks (WSNs), a multipath routing protocol (MRP) based on dynamic clustering and ant colony optimization (ACO) is proposed.. Such an approach can maximize the network lifetime and reduce the energy consumption. An
[...] Read more.
For monitoring burst events in a kind of reactive wireless sensor networks (WSNs), a multipath routing protocol (MRP) based on dynamic clustering and ant colony optimization (ACO) is proposed.. Such an approach can maximize the network lifetime and reduce the energy consumption. An important attribute of WSNs is their limited power supply, and therefore some metrics (such as energy consumption of communication among nodes, residual energy, path length) were considered as very important criteria while designing routing in the MRP. Firstly, a cluster head (CH) is selected among nodes located in the event area according to some parameters, such as residual energy. Secondly, an improved ACO algorithm is applied in the search for multiple paths between the CH and sink node. Finally, the CH dynamically chooses a route to transmit data with a probability that depends on many path metrics, such as energy consumption. The simulation results show that MRP can prolong the network lifetime, as well as balance of energy consumption among nodes and reduce the average energy consumption effectively. Full article
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Open AccessCommunication Intelligent Gearbox Diagnosis Methods Based on SVM, Wavelet Lifting and RBR
Sensors 2010, 10(5), 4602-4621; doi:10.3390/s100504602
Received: 22 March 2010 / Revised: 19 April 2010 / Accepted: 27 April 2010 / Published: 4 May 2010
Cited by 12 | PDF Full-text (674 KB) | HTML Full-text | XML Full-text
Abstract
Given the problems in intelligent gearbox diagnosis methods, it is difficult to obtain the desired information and a large enough sample size to study; therefore, we propose the application of various methods for gearbox fault diagnosis, including wavelet lifting, a support vector machine
[...] Read more.
Given the problems in intelligent gearbox diagnosis methods, it is difficult to obtain the desired information and a large enough sample size to study; therefore, we propose the application of various methods for gearbox fault diagnosis, including wavelet lifting, a support vector machine (SVM) and rule-based reasoning (RBR). In a complex field environment, it is less likely for machines to have the same fault; moreover, the fault features can also vary. Therefore, a SVM could be used for the initial diagnosis. First, gearbox vibration signals were processed with wavelet packet decomposition, and the signal energy coefficients of each frequency band were extracted and used as input feature vectors in SVM for normal and faulty pattern recognition. Second, precision analysis using wavelet lifting could successfully filter out the noisy signals while maintaining the impulse characteristics of the fault; thus effectively extracting the fault frequency of the machine. Lastly, the knowledge base was built based on the field rules summarized by experts to identify the detailed fault type. Results have shown that SVM is a powerful tool to accomplish gearbox fault pattern recognition when the sample size is small, whereas the wavelet lifting scheme can effectively extract fault features, and rule-based reasoning can be used to identify the detailed fault type. Therefore, a method that combines SVM, wavelet lifting and rule-based reasoning ensures effective gearbox fault diagnosis. Full article
Open AccessArticle A Novel Radar Sensor for the Non-Contact Detection of Speech Signals
Sensors 2010, 10(5), 4622-4633; doi:10.3390/s100504622
Received: 26 March 2010 / Revised: 28 April 2010 / Accepted: 29 April 2010 / Published: 4 May 2010
Cited by 13 | PDF Full-text (301 KB) | HTML Full-text | XML Full-text
Abstract
Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to
[...] Read more.
Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to detect speech signals. The utilization of a high operating frequency and a superheterodyne receiver contributes to the high sensitivity of the radar sensor for small sound vibrations. In addition, the penetrability of microwaves allows the novel sensor to detect speech signals through nonmetal barriers. Results show that the novel sensor can detect high frequency speech energies and that the speech quality is comparable to traditional microphone speech. Moreover, the novel sensor can detect speech signals through a nonmetal material of a certain thickness between the sensor and the subject. Thus, the novel speech sensor expands traditional speech detection techniques and provides an exciting alternative for broader application prospects. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Time Delay for Aerial Ammonia Concentration Measurements in Livestock Buildings
Sensors 2010, 10(5), 4634-4642; doi:10.3390/s100504634
Received: 1 March 2010 / Revised: 29 March 2010 / Accepted: 15 April 2010 / Published: 4 May 2010
Cited by 14 | PDF Full-text (171 KB) | HTML Full-text | XML Full-text
Abstract
Correct measurements of ammonia concentration in air still present considerable challenges. The high water solubility and polarity can cause it to adsorb on surfaces in the entire sampling system, including sampling lines, filters, valves, pumps and instruments, causing substantial measuring errors and time
[...] Read more.
Correct measurements of ammonia concentration in air still present considerable challenges. The high water solubility and polarity can cause it to adsorb on surfaces in the entire sampling system, including sampling lines, filters, valves, pumps and instruments, causing substantial measuring errors and time delays. To estimate time delay characteristics of a Photo Acoustic Multi Gas Monitor 1312 and a Multi Point Sampler continuous measurement of aerial ammonia concentrations at different levels was performed. In order to obtain reproducible data, a wind tunnel was used to generate selected concentrations inside and a background concentration representing the air inlet of the tunnel. Four different concentration levels (0.8 ppm, 6.2 ppm, 9.7 ppm and 13.7 ppm) were used in the experiments, with an additional outdoor concentration level as background. The results indicated a substantial time delay when switching between the measuring positions with high and low concentration and vice versa. These properties may course serious errors for estimation of e.g. gas emissions whenever more than one measuring channel is applied. To reduce the measurement errors, some suggestions regarding design of the measurement setup and measuring strategies were presented. Full article
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Open AccessArticle A Novel pH-dependent Drift Improvement Method for Zirconium Dioxide Gated pH-Ion Sensitive Field Effect Transistors
Sensors 2010, 10(5), 4643-4654; doi:10.3390/s100504643
Received: 10 March 2010 / Revised: 15 April 2010 / Accepted: 28 April 2010 / Published: 5 May 2010
Cited by 17 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
A novel compensation method for Zirconium dioxide gated Ion Sensitive Field Effect Transistors (ISFETs) to improve pH-dependent drift was demonstrated. Through the sequential measurements for both the n-channel and p-channel ISFETs, 75–100% pH-dependent drift could be successfully suppressed for the first seven hours.
[...] Read more.
A novel compensation method for Zirconium dioxide gated Ion Sensitive Field Effect Transistors (ISFETs) to improve pH-dependent drift was demonstrated. Through the sequential measurements for both the n-channel and p-channel ISFETs, 75–100% pH-dependent drift could be successfully suppressed for the first seven hours. As a result, a nearly constant drift rate versus pH value was obtained, which increases the accuracy of pH measurements. Meanwhile, the drawback of the hyperbolic-like change with time of the common drift behavior for ISFETs was improved. A state-of-the-art integrated scheme adopting this method was also illustrated. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle State-of-the-Art Sensor Technology in Spain: Invasive and Non-Invasive Techniques for Monitoring Respiratory Variables
Sensors 2010, 10(5), 4655-4674; doi:10.3390/s100504655
Received: 4 March 2010 / Revised: 29 March 2010 / Accepted: 15 April 2010 / Published: 5 May 2010
Cited by 5 | PDF Full-text (212 KB) | HTML Full-text | XML Full-text
Abstract
The interest in measuring physiological parameters (especially arterial blood gases) has grown progressively in parallel to the development of new technologies. Physiological parameters were first measured invasively and at discrete time points; however, it was clearly desirable to measure them continuously and non-invasively.
[...] Read more.
The interest in measuring physiological parameters (especially arterial blood gases) has grown progressively in parallel to the development of new technologies. Physiological parameters were first measured invasively and at discrete time points; however, it was clearly desirable to measure them continuously and non-invasively. The development of intensive care units promoted the use of ventilators via oral intubation ventilators via oral intubation and mechanical respiratory variables were progressively studied. Later, the knowledge gained in the hospital was applied to out-of-hospital management. In the present paper we review the invasive and non-invasive techniques for monitoring respiratory variables. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle Classification of Agarwood Oil Using an Electronic Nose
Sensors 2010, 10(5), 4675-4685; doi:10.3390/s100504675
Received: 1 March 2010 / Revised: 14 April 2010 / Accepted: 19 April 2010 / Published: 6 May 2010
Cited by 22 | PDF Full-text (303 KB) | HTML Full-text | XML Full-text
Abstract
Presently, the quality assurance of agarwood oil is performed by sensory panels which has significant drawbacks in terms of objectivity and repeatability. In this paper, it is shown how an electronic nose (e-nose) may be successfully utilised for the classification of agarwood oil.
[...] Read more.
Presently, the quality assurance of agarwood oil is performed by sensory panels which has significant drawbacks in terms of objectivity and repeatability. In this paper, it is shown how an electronic nose (e-nose) may be successfully utilised for the classification of agarwood oil. Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA), were used to classify different types of oil. The HCA produced a dendrogram showing the separation of e-nose data into three different groups of oils. The PCA scatter plot revealed a distinct separation between the three groups. An Artificial Neural Network (ANN) was used for a better prediction of unknown samples. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Diode Laser Detection of Greenhouse Gases in the Near-Infrared Region by Wavelength Modulation Spectroscopy: Pressure Dependence of the Detection Sensitivity
Sensors 2010, 10(5), 4686-4699; doi:10.3390/s100504686
Received: 27 January 2010 / Revised: 13 April 2010 / Accepted: 16 April 2010 / Published: 6 May 2010
Cited by 14 | PDF Full-text (502 KB) | HTML Full-text | XML Full-text
Abstract
We have investigated the pressure dependence of the detection sensitivity of CO2, N2O and CH4 using wavelength modulation spectroscopy (WMS) with distributed feed-back diode lasers in the near infrared region. The spectral line shapes and the background noise
[...] Read more.
We have investigated the pressure dependence of the detection sensitivity of CO2, N2O and CH4 using wavelength modulation spectroscopy (WMS) with distributed feed-back diode lasers in the near infrared region. The spectral line shapes and the background noise of the second harmonics (2f) detection of the WMS were analyzed theoretically. We determined the optimum pressure conditions in the detection of CO2, N2O and CH4, by taking into consideration the background noise in the WMS. At the optimum total pressure for the detection of CO2, N2O and CH4, the limits of detection in the present system were determined. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle An Overview of Recent Application of Medical Infrared Thermography in Sports Medicine in Austria
Sensors 2010, 10(5), 4700-4715; doi:10.3390/s100504700
Received: 10 March 2010 / Revised: 2 April 2010 / Accepted: 20 April 2010 / Published: 7 May 2010
Cited by 50 | PDF Full-text (456 KB) | HTML Full-text | XML Full-text
Abstract
Medical infrared thermography (MIT) is used for analyzing physiological functions related to skin temperature. Technological advances have made MIT a reliable medical measurement tool. This paper provides an overview of MIT´s technical requirements and usefulness in sports medicine, with a special focus on
[...] Read more.
Medical infrared thermography (MIT) is used for analyzing physiological functions related to skin temperature. Technological advances have made MIT a reliable medical measurement tool. This paper provides an overview of MIT´s technical requirements and usefulness in sports medicine, with a special focus on overuse and traumatic knee injuries. Case studies are used to illustrate the clinical applicability and limitations of MIT. It is concluded that MIT is a non-invasive, non-radiating, low cost detection tool which should be applied for pre-scanning athletes in sports medicine. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Austria)
Open AccessArticle Signal Existence Verification (SEV) for GPS Low Received Power Signal Detection Using the Time-Frequency Approach
Sensors 2010, 10(5), 4717-4738; doi:10.3390/s100504717
Received: 29 March 2010 / Revised: 30 April 2010 / Accepted: 4 May 2010 / Published: 10 May 2010
Cited by 2 | PDF Full-text (1451 KB) | HTML Full-text | XML Full-text
Abstract
The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper
[...] Read more.
The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper proposes a signal existence verification (SEV) process to detect and subsequently verify low received power GPS signals. The SEV process is based on the time-frequency representation of GPS signal, and it can capture the characteristic of GPS signal in the time-frequency plane to enhance the GPS signal acquisition performance. Several simulations and experiments are conducted to show the effectiveness of the proposed method for low received power signal detection. The contribution of this work is that the SEV process is an additional scheme to assist the GPS signal acquisition process in low received power signal detection, without changing the original signal acquisition or tracking algorithms. Full article
Open AccessArticle Biosensing for the Environment and Defence: Aqueous Uranyl Detection Using Bacterial Surface Layer Proteins
Sensors 2010, 10(5), 4739-4755; doi:10.3390/s100504739
Received: 5 March 2010 / Revised: 22 April 2010 / Accepted: 27 April 2010 / Published: 10 May 2010
Cited by 7 | PDF Full-text (433 KB) | HTML Full-text | XML Full-text
Abstract
The fabrication of novel uranyl (UO22+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self
[...] Read more.
The fabrication of novel uranyl (UO22+) binding protein based sensors is reported. The new biosensor responds to picomolar levels of aqueous uranyl ions within minutes using Lysinibacillus sphaericus JG-A12 S-layer protein tethered to gold electrodes. In comparison to traditional self assembled monolayer based biosensors the porous bioconjugated layer gave greater stability, longer electrode life span and a denser protein layer. Biosensors responded specifically to UO22+ ions and showed minor interference from Ni2+, Cs+, Cd2+ and Co2+. Chemical modification of JG-A12 protein phosphate and carboxyl groups prevented UO22+ binding, showing that both moieties are involved in the recognition to UO22+. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
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Open AccessArticle Fiber Bragg Grating Sensor to Monitor Stress Kinetics in Drying Process of Commercial Latex Paints
Sensors 2010, 10(5), 4761-4776; doi:10.3390/s100504761
Received: 3 February 2010 / Revised: 25 April 2010 / Accepted: 28 April 2010 / Published: 11 May 2010
Cited by 6 | PDF Full-text (565 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we report a study about the application of packaged fiber Bragg gratings used as strain sensors to monitor the stress kinetics during the drying process of commercial latex paints. Three stages of drying with distinct mechanical deformation and temporal behaviors
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In this paper, we report a study about the application of packaged fiber Bragg gratings used as strain sensors to monitor the stress kinetics during the drying process of commercial latex paints. Three stages of drying with distinct mechanical deformation and temporal behaviors were identified for the samples, with mechanical deformation from 15 μm to 21 μm in the longitudinal film dimension on time intervals from 370 to 600 minutes. Drying time tests based on human sense technique described by the Brazilian Technical Standards NBR 9558 were also done. The results obtained shows that human sense technique has a limited perception of the drying process and that the optical measurement system proposed can be used to characterize correctly the dry-through stage of paint. The influence of solvent (water) addition in the drying process was also investigated. The paint was diluted with four parts paint and one part water (80% paint), and one part paint and one part water (50% paint). It was observed that the increase of the water ratio mixed into the paint decreases both the mechanical deformation magnitude and the paint dry-through time. Contraction of 5.2 μm and 10.4 μm were measured for concentrations of 50% and 80% of paint in the mixture, respectively. For both diluted paints the dry-through time was approximately 170 minutes less than undiluted paint. The optical technique proposed in this work can contribute to the development of new standards to specify the drying time of paint coatings. Full article
(This article belongs to the Special Issue Advances in Transducers)
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Open AccessArticle A Power-Efficient Bio-Potential Acquisition Device with DS-MDE Sensors for Long-Term Healthcare Monitoring Applications
Sensors 2010, 10(5), 4777-4793; doi:10.3390/s100504777
Received: 2 March 2010 / Revised: 21 April 2010 / Accepted: 27 April 2010 / Published: 11 May 2010
Cited by 13 | PDF Full-text (522 KB) | HTML Full-text | XML Full-text
Abstract
This work describes a power-efficient bio-potential acquisition device for long-term healthcare applications that is implemented using novel microelectromechanical dry electrodes (MDE) and a low power bio-potential processing chip. Using micromachining technology, an attempt is also made to enhance the sensing reliability and stability
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This work describes a power-efficient bio-potential acquisition device for long-term healthcare applications that is implemented using novel microelectromechanical dry electrodes (MDE) and a low power bio-potential processing chip. Using micromachining technology, an attempt is also made to enhance the sensing reliability and stability by fabricating a diamond-shaped MDE (DS-MDE) that has a satisfactory self-stability capability and superior electric conductivity when attached onto skin without any extra skin tissue injury technology. To acquire differential bio-potentials such as ECG signals, the proposed processing chip fabricated in a standard CMOS process has a high common mode rejection ratio (C.M.R.R.) differential amplifier and a 12-bit analog-to-digital converter (ADC). Use of the proposed system and integrate simple peripheral commercial devices can obtain the ECG signal efficiently without additional skin tissue injury and ensure continuous monitoring more than 70 hours with a 400 mAh battery. Full article
Open AccessArticle A Multi-D-Shaped Optical Fiber for Refractive Index Sensing
Sensors 2010, 10(5), 4794-4804; doi:10.3390/s100504794
Received: 10 March 2010 / Revised: 29 March 2010 / Accepted: 14 April 2010 / Published: 11 May 2010
Cited by 39 | PDF Full-text (630 KB) | HTML Full-text | XML Full-text
Abstract
A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated
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A novel class of multi-D-shaped optical fiber suited for refractive index measurements is presented. The multi-D-shaped optical fiber was constructed by forming several D-sections in a multimode optical fiber at localized regions with femtosecond laser pulses. The total number of D-shaped zones fabricated could range from three to seven. Each D-shaped zone covered a sensor volume of 100 μm depth, 250 μm width, and 1 mm length. The mean roughness of the core surface obtained by the AFM images was 231.7 nm, which is relatively smooth. Results of the tensile test indicated that the fibers have sufficient mechanical strength to resist damage from further processing. The multi-D-shaped optical fiber as a high sensitive refractive-index sensor to detect changes in the surrounding refractive index was studied. The results for different concentrations of sucrose solution show that a resolution of 1.27 × 103–3.13 × 10−4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the multi-D-shaped fibers are attractive for chemical, biological, and biochemical sensing with aqueous solutions. Full article
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Open AccessArticle Real Time Speed Estimation of Moving Vehicles from Side View Images from an Uncalibrated Video Camera
Sensors 2010, 10(5), 4805-4824; doi:10.3390/s100504805
Received: 28 December 2009 / Revised: 12 April 2010 / Accepted: 22 April 2010 / Published: 11 May 2010
Cited by 17 | PDF Full-text (575 KB) | HTML Full-text | XML Full-text
Abstract
In order to estimate the speed of a moving vehicle with side view camera images, velocity vectors of a sufficient number of reference points identified on the vehicle must be found using frame images. This procedure involves two main steps. In the first
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In order to estimate the speed of a moving vehicle with side view camera images, velocity vectors of a sufficient number of reference points identified on the vehicle must be found using frame images. This procedure involves two main steps. In the first step, a sufficient number of points from the vehicle is selected, and these points must be accurately tracked on at least two successive video frames. In the second step, by using the displacement vectors of the tracked points and passed time, the velocity vectors of those points are computed. Computed velocity vectors are defined in the video image coordinate system and displacement vectors are measured by the means of pixel units. Then the magnitudes of the computed vectors in image space should be transformed to the object space to find the absolute values of these magnitudes. This transformation requires an image to object space information in a mathematical sense that is achieved by means of the calibration and orientation parameters of the video frame images. This paper presents proposed solutions for the problems of using side view camera images mentioned here. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle GPCA vs. PCA in Recognition and 3-D Localization of Ultrasound Reflectors
Sensors 2010, 10(5), 4825-4837; doi:10.3390/s100504825
Received: 25 February 2010 / Revised: 20 April 2010 / Accepted: 7 May 2010 / Published: 11 May 2010
Cited by 2 | PDF Full-text (341 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a new method of classification and localization of reflectors, using the time-of-flight (TOF) data obtained from ultrasonic transducers, is presented. The method of classification and localization is based on Generalized Principal Component Analysis (GPCA) applied to the TOF values obtained
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In this paper, a new method of classification and localization of reflectors, using the time-of-flight (TOF) data obtained from ultrasonic transducers, is presented. The method of classification and localization is based on Generalized Principal Component Analysis (GPCA) applied to the TOF values obtained from a sensor that contains four ultrasound emitters and 16 receivers. Since PCA works with vectorized representations of TOF, it does not take into account the spatial locality of receivers. The GPCA works with two-dimensional representations of TOF, taking into account information on the spatial position of the receivers. This report includes a detailed description of the method of classification and localization and the results of achieved tests with three types of reflectors in 3-D environments: planes, edges, and corners. The results in terms of processing time, classification and localization were very satisfactory for the reflectors located in the range of 50–350 cm. Full article
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Open AccessArticle Novel Feature Modelling the Prediction and Detection of sEMG Muscle Fatigue towards an Automated Wearable System
Sensors 2010, 10(5), 4838-4854; doi:10.3390/s100504838
Received: 22 April 2010 / Revised: 28 April 2010 / Accepted: 7 May 2010 / Published: 12 May 2010
Cited by 10 | PDF Full-text (1389 KB) | HTML Full-text | XML Full-text
Abstract
Surface Electromyography (sEMG) activity of the biceps muscle was recorded from ten subjects performing isometric contraction until fatigue. A novel feature (1D spectro_std) was used to extract the feature that modeled three classes of fatigue, which enabled the prediction and detection of fatigue.
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Surface Electromyography (sEMG) activity of the biceps muscle was recorded from ten subjects performing isometric contraction until fatigue. A novel feature (1D spectro_std) was used to extract the feature that modeled three classes of fatigue, which enabled the prediction and detection of fatigue. Initial results of class separation were encouraging, discriminating between the three classes of fatigue, a longitudinal classification on Non-Fatigue and Transition-to-Fatigue shows 81.58% correct classification with accuracy 0.74 of correct predictions while the longitudinal classification on Transition-to-Fatigue and Fatigue showed lower average correct classification of 66.51% with a positive classification accuracy 0.73 of correct prediction. Comparison of the 1D spectro_std with other sEMG fatigue features on the same dataset show a significant improvement in classification, where results show a significant 20.58% (p < 0.01) improvement when using the 1D spectro_std to classify Non-Fatigue and Transition-to-Fatigue. In classifying Transition-to-Fatigue and Fatigue results also show a significant improvement over the other features giving 8.14% (p < 0.05) on average of all compared features. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Solvent Vapour Detection with Cholesteric Liquid Crystals—Optical and Mass-Sensitive Evaluation of the Sensor Mechanism
Sensors 2010, 10(5), 4887-4897; doi:10.3390/s100504887
Received: 18 March 2010 / Revised: 4 May 2010 / Accepted: 6 May 2010 / Published: 12 May 2010
Cited by 29 | PDF Full-text (203 KB) | HTML Full-text | XML Full-text
Abstract
Cholesteric liquid crystals (CLCs) are used as sensitive coatings for the detection of organic solvent vapours for both polar and non-polar substances. The incorporation of different analyte vapours in the CLC layers disturbs the pitch length which changes the optical properties, i.e.,
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Cholesteric liquid crystals (CLCs) are used as sensitive coatings for the detection of organic solvent vapours for both polar and non-polar substances. The incorporation of different analyte vapours in the CLC layers disturbs the pitch length which changes the optical properties, i.e., shifting the absorption band. The engulfing of CLCs around non-polar solvent vapours such as tetrahedrofuran (THF), chloroform and tetrachloroethylene is favoured in comparison to polar ones, i.e., methanol and ethanol. Increasing solvent vapour concentrations shift the absorbance maximumto smaller wavelengths, e.g., as observed for THF. Additionally, CLCs have been coated on acoustic devices such as the quartz crystal microbalance (QCM) to measure the frequency shift of analyte samples at similar concentration levels. The mass effect for tetrachloroethylene was about six times higher than chloroform. Thus, optical response can be correlated with intercalation in accordance to mass detection. The mechanical stability was gained by combining CLCs with imprinted polymers. Therefore, pre-concentration of solvent vapours was performed leading to an additional selectivity. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessCommunication High Sensitivity Carbon Nanotubes Flow-Rate Sensors and Their Performance Improvement by Coating
Sensors 2010, 10(5), 4898-4906; doi:10.3390/s100504898
Received: 26 March 2010 / Revised: 17 April 2010 / Accepted: 25 April 2010 / Published: 14 May 2010
Cited by 7 | PDF Full-text (473 KB) | HTML Full-text | XML Full-text
Abstract
A new type of hot-wire flow-rate sensor (HWFS) with a sensing element made of a macro-sized carbon nanotube (CNT) strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2
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A new type of hot-wire flow-rate sensor (HWFS) with a sensing element made of a macro-sized carbon nanotube (CNT) strand is presented in this study. An effective way to improve repeatability of the CNT flow-rate sensor by coating a layer of Al2O3 on the CNT surface is proposed. Experimental results show that due to the large surface-to-volume ratio and thin coated Al2O3 layer, the CNT flow-rate sensor has higher sensitivity and faster response than a conventional platinum (Pt) HWFS. It is also demonstrated that the covered CNT flow-rate sensor has better repeatability than its bare counterpart due to insulation from the surrounding environment. The proposed CNT flow-rate sensor shows application potential for high-sensitivity measurement of flow rate. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Comparative Laser Spectroscopy Diagnostics for Ancient Metallic Artefacts Exposed to Environmental Pollution
Sensors 2010, 10(5), 4926-4949; doi:10.3390/s100504926
Received: 3 February 2010 / Revised: 29 April 2010 / Accepted: 4 May 2010 / Published: 14 May 2010
Cited by 13 | PDF Full-text (2048 KB) | HTML Full-text | XML Full-text
Abstract
Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are
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Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This paper presents analyses of the chemical composition and stratigraphy of corrosion products with the use of laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy. The discussion of the results is supported by material studies (SEM-EDS, XRF, ion-analyses). The tests were performed on several samples taken from original objects, including copper roofing from Wilanów Palace in Warsaw and Karol Poznański Palace in Łódź, bronze decorative figures from the Wilanów Palace gardens, and four archaeological examples of old jewellery (different copper alloys). Work has been performed as a part of the MATLAS project in the frames of EEA and Norway Grants (www.matlas.eu) and the results enable the comparison of the methodology and to elaborate the joint diagnostic procedures of the three project partner independent laboratories. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle Level Set Approach to Anisotropic Wet Etching of Silicon
Sensors 2010, 10(5), 4950-4967; doi:10.3390/s100504950
Received: 31 December 2009 / Revised: 8 April 2010 / Accepted: 13 April 2010 / Published: 17 May 2010
Cited by 17 | PDF Full-text (743 KB) | HTML Full-text | XML Full-text
Abstract
In this paper a methodology for the three dimensional (3D) modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon
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In this paper a methodology for the three dimensional (3D) modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon symmetry properties, by means of the interpolation technique using experimentally obtained values for the etching rates along thirteen principal and high index directions in KOH solutions. The resulting level set equations are solved using an open source implementation of the sparse field method (ITK library, developed in medical image processing community), extended for the case of non-convex Hamiltonians. Simulation results for some interesting initial 3D shapes, as well as some more practical examples illustrating anisotropic etching simulation in the presence of masks (simple square aperture mask, convex corner undercutting and convex corner compensation, formation of suspended structures) are shown also. The obtained results show that level set method can be used as an effective tool for wet etching process modeling, and that is a viable alternative to the Cellular Automata method which now prevails in the simulations of the wet etching process. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Testing ZigBee Motes for Monitoring Refrigerated Vegetable Transportation under Real Conditions
Sensors 2010, 10(5), 4968-4982; doi:10.3390/s100504968
Received: 23 March 2010 / Revised: 7 April 2010 / Accepted: 30 April 2010 / Published: 18 May 2010
Cited by 16 | PDF Full-text (639 KB) | HTML Full-text | XML Full-text
Abstract
Quality control and monitoring of perishable goods during transportation and delivery services is an increasing concern for producers, suppliers, transport decision makers and consumers. The major challenge is to ensure a continuous ‘cold chain’ from producer to consumer in order to guaranty prime
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Quality control and monitoring of perishable goods during transportation and delivery services is an increasing concern for producers, suppliers, transport decision makers and consumers. The major challenge is to ensure a continuous ‘cold chain’ from producer to consumer in order to guaranty prime condition of goods. In this framework, the suitability of ZigBee protocol for monitoring refrigerated transportation has been proposed by several authors. However, up to date there was not any experimental work performed under real conditions. Thus, the main objective of our experiment was to test wireless sensor motes based in the ZigBee/IEEE 802.15.4 protocol during a real shipment. The experiment was conducted in a refrigerated truck traveling through two countries (Spain and France) which means a journey of 1,051 kilometers. The paper illustrates the great potential of this type of motes, providing information about several parameters such as temperature, relative humidity, door openings and truck stops. Psychrometric charts have also been developed for improving the knowledge about water loss and condensation on the product during shipments. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Detecting Nano-Scale Vibrations in Rotating Devices by Using Advanced Computational Methods
Sensors 2010, 10(5), 4983-4995; doi:10.3390/s100504983
Received: 3 March 2010 / Revised: 27 April 2010 / Accepted: 6 May 2010 / Published: 18 May 2010
Cited by 1 | PDF Full-text (730 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a computational method for detecting vibrations related to eccentricity in ultra precision rotation devices used for nano-scale manufacturing. The vibration is indirectly measured via a frequency domain analysis of the signal from a piezoelectric sensor attached to the stationary component
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This paper presents a computational method for detecting vibrations related to eccentricity in ultra precision rotation devices used for nano-scale manufacturing. The vibration is indirectly measured via a frequency domain analysis of the signal from a piezoelectric sensor attached to the stationary component of the rotating device. The algorithm searches for particular harmonic sequences associated with the eccentricity of the device rotation axis. The detected sequence is quantified and serves as input to a regression model that estimates the eccentricity. A case study presents the application of the computational algorithm during precision manufacturing processes. Full article
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Open AccessArticle Diffused Matrix Format: A New Storage and Processing Format for Airborne Hyperspectral Sensor Images
Sensors 2010, 10(5), 4996-5013; doi:10.3390/s100504996
Received: 12 March 2010 / Revised: 27 April 2010 / Accepted: 6 May 2010 / Published: 18 May 2010
Cited by 3 | PDF Full-text (1305 KB) | HTML Full-text | XML Full-text
Abstract
At present, hyperspectral images are mainly obtained with airborne sensors that are subject to turbulences while the spectrometer is acquiring the data. Therefore, geometric corrections are required to produce spatially correct images for visual interpretation and change detection analysis. This paper analyzes the
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At present, hyperspectral images are mainly obtained with airborne sensors that are subject to turbulences while the spectrometer is acquiring the data. Therefore, geometric corrections are required to produce spatially correct images for visual interpretation and change detection analysis. This paper analyzes the data acquisition process of airborne sensors. The main objective is to propose a new data format called Diffused Matrix Format (DMF) adapted to the sensor's characteristics including its spectral and spatial information. The second objective is to compare the accuracy of the quantitative maps derived by using the DMF data structure with those obtained from raster images based on traditional data structures. Results show that DMF processing is more accurate and straightforward than conventional image processing of remotely sensed data with the advantage that the DMF file structure requires less storage space than other data formats. In addition the data processing time does not increase when DMF is used. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle Low Light CMOS Contact Imager with an Integrated Poly-Acrylic Emission Filter for Fluorescence Detection
Sensors 2010, 10(5), 5014-5027; doi:10.3390/s100505014
Received: 18 March 2010 / Revised: 2 May 2010 / Accepted: 4 May 2010 / Published: 19 May 2010
Cited by 14 | PDF Full-text (281 KB) | HTML Full-text | XML Full-text
Abstract
This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution
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This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert’s law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Flexible Proximity Sensor Fully Fabricated by Inkjet Printing
Sensors 2010, 10(5), 5054-5062; doi:10.3390/s100505054
Received: 9 March 2010 / Revised: 11 May 2010 / Accepted: 14 May 2010 / Published: 19 May 2010
Cited by 34 | PDF Full-text (398 KB) | HTML Full-text | XML Full-text
Abstract
A flexible proximity sensor fully fabricated by inkjet printing is proposed in this paper. The flexible proximity sensor is composed of a ZnO layer sandwiched in between a flexible aluminum sheet and a web-shaped top electrode layer. The flexible aluminum sheet serves as
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A flexible proximity sensor fully fabricated by inkjet printing is proposed in this paper. The flexible proximity sensor is composed of a ZnO layer sandwiched in between a flexible aluminum sheet and a web-shaped top electrode layer. The flexible aluminum sheet serves as the bottom electrode. The material of the top electrode layer is nano silver. Both the ZnO and top electrode layers are deposited by inkjet printing. The fully inkjet printing process possesses the advantages of direct patterning and low-cost. It does not require photolithography and etching processes since the pattern is directly printed on the flexible aluminum sheet. The prototype demonstrates that the presented flexible sensor is sensitive to the human body. It may be applied to proximity sensing or thermal eradiation sensing. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Novel Microwave-Assisted Synthesis of Poly(D,L-lactide): The Influence of Monomer/Initiator Molar Ratio on the Product Properties
Sensors 2010, 10(5), 5063-5073; doi:10.3390/s100505063
Received: 29 March 2010 / Revised: 26 April 2010 / Accepted: 28 April 2010 / Published: 20 May 2010
Cited by 19 | PDF Full-text (894 KB) | HTML Full-text | XML Full-text
Abstract
Poly(D,L-lactide) synthesis using tin(II) 2-ethylhexanoate initiated ring-opening polymerization (ROP) takes over 30 hours in bulk at 120 °C. The use of microwave makes the same bulk polymerization process with the same initiator much faster and energy saving, with a reaction time of about
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Poly(D,L-lactide) synthesis using tin(II) 2-ethylhexanoate initiated ring-opening polymerization (ROP) takes over 30 hours in bulk at 120 °C. The use of microwave makes the same bulk polymerization process with the same initiator much faster and energy saving, with a reaction time of about 30 minutes at 100 °C. Here, the poly(lactide) synthesis was done in a microwave reactor, using frequency of 2.45 GHz and maximal power of 150 W. The reaction temperature was controlled via infra-red system for in-bulk-measuring, and was maintained at 100 °C. Different molar ratios of monomer and initiator, [M]/[I], of 1,000, 5,000 and 10,000 were used. The achieved average molar masses for the obtained polymers (determined by gel permeation chromatography) were in the interval from 26,700 to 112,500 g/mol. The polydispersion index was from 2.436 to 3.425. For applicative purposes, the obtained material was purified during the procedure of microsphere preparation. Microspheres were obtained by spraying a fine fog of polymer (D,L-lactide) solution in tetrahydrofuran into the water solution of poly(vinyl alcohol) with intensive stirring. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Characterization of Mixed xWO3(1-x)Y2O3 Nanoparticle Thick Film for Gas Sensing Application
Sensors 2010, 10(5), 5074-5089; doi:10.3390/s100505074
Received: 29 March 2010 / Revised: 27 April 2010 / Accepted: 28 April 2010 / Published: 25 May 2010
Cited by 11 | PDF Full-text (889 KB) | HTML Full-text | XML Full-text
Abstract
Microstructural, topology, inner morphology, and gas-sensitivity of mixed xWO3(1-x)Y2O3 nanoparticles (x = 1, 0.95, 0.9, 0.85, 0.8) thick-film semiconductor gas sensors were studied. The surface topography and inner morphological properties of the mixed powder
[...] Read more.
Microstructural, topology, inner morphology, and gas-sensitivity of mixed xWO3(1-x)Y2O3 nanoparticles (x = 1, 0.95, 0.9, 0.85, 0.8) thick-film semiconductor gas sensors were studied. The surface topography and inner morphological properties of the mixed powder and sensing film were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Also, gas sensitivity properties of the printed films were evaluated in the presence of methane (CH4) and butane (C4H10) at up to 500 °C operating temperature of the sensor. The results show that the doping agent can modify some structural properties and gas sensitivity of the mixed powder. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Highly Sensitive Enzyme-Amplified Immunosensor Based on a Nanoporous Niobium Oxide (Nb2O5) Electrode
Sensors 2010, 10(5), 5160-5170; doi:10.3390/s100505160
Received: 26 March 2010 / Revised: 13 April 2010 / Accepted: 10 May 2010 / Published: 25 May 2010
Cited by 8 | PDF Full-text (1033 KB) | HTML Full-text | XML Full-text
Abstract
We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb2O5) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of
[...] Read more.
We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb2O5) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb2O5 were used to obtain a powerful signal amplification of the electrochemical immunobiosensor. The method using this electrochemical biosensor based on an Au@Nb2O5 electrode provides a much better performance than those based on conventional bulk gold or niobium oxide electrodes. Our novel approach does not require any time-consuming cleaning steps to yield reproducible electrochemical signals. In addition, the strong adhesion of gold films on the niobium oxide electrodes offers a very stable substrate during electrochemical biosensing. Cyclic voltammetry measurements indicate that non-specific binding of proteins to the modified Au@Nb2O5 surface is sufficiently low to be ignored in the case of our novel system. Finally, we demonstrated the ability of the biosensor based on an Au@Nb2O5 offering the enhanced performance with a high resolution and sensitivity. Therefore, it is expected that the biosensor based on an Au@Nb2O5 has great potential for highly efficient biological devices. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle A Reusable PZT Transducer for Monitoring Initial Hydration and Structural Health of Concrete
Sensors 2010, 10(5), 5193-5208; doi:10.3390/s100505193
Received: 19 March 2010 / Revised: 18 May 2010 / Accepted: 18 May 2010 / Published: 25 May 2010
Cited by 26 | PDF Full-text (827 KB) | HTML Full-text | XML Full-text
Abstract
During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for
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During the construction of a concrete structure, strength monitoring is important to ensure the safety of both personnel and the structure. Furthermore, to increase the efficiency of in situ casting or precast of concrete, determining the optimal time of demolding is important for concrete suppliers. Surface bonded lead zirconate titanate (PZT) transducers have been used for damage detection and parameter identification for various engineering structures over the last two decades. In this work, a reusable PZT transducer setup for monitoring initial hydration of concrete and structural health is developed, where a piece of PZT is bonded to an enclosure with two bolts tightened inside the holes drilled in the enclosure. An impedance analyzer is used to acquire the admittance signatures of the PZT. Root mean square deviation (RMSD) is employed to associate the change in concrete strength with changes in the PZT admittance signatures. The results show that the reusable setup is able to effectively monitor the initial hydration of concrete and the structural health. It can also be detached from the concrete for future re-use. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Estimation of Visual Maps with a Robot Network Equipped with Vision Sensors
Sensors 2010, 10(5), 5209-5232; doi:10.3390/s100505209
Received: 11 February 2010 / Revised: 31 March 2010 / Accepted: 14 April 2010 / Published: 25 May 2010
Cited by 14 | PDF Full-text (2746 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present an approach to the Simultaneous Localization and Mapping (SLAM) problem using a team of autonomous vehicles equipped with vision sensors. The SLAM problem considers the case in which a mobile robot is equipped with a particular sensor, moves
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In this paper we present an approach to the Simultaneous Localization and Mapping (SLAM) problem using a team of autonomous vehicles equipped with vision sensors. The SLAM problem considers the case in which a mobile robot is equipped with a particular sensor, moves along the environment, obtains measurements with its sensors and uses them to construct a model of the space where it evolves. In this paper we focus on the case where several robots, each equipped with its own sensor, are distributed in a network and view the space from different vantage points. In particular, each robot is equipped with a stereo camera that allow the robots to extract visual landmarks and obtain relative measurements to them. We propose an algorithm that uses the measurements obtained by the robots to build a single accurate map of the environment. The map is represented by the three-dimensional position of the visual landmarks. In addition, we consider that each landmark is accompanied by a visual descriptor that encodes its visual appearance. The solution is based on a Rao-Blackwellized particle filter that estimates the paths of the robots and the position of the visual landmarks. The validity of our proposal is demonstrated by means of experiments with a team of real robots in a office-like indoor environment. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle NEURON: Enabling Autonomicity in Wireless Sensor Networks
Sensors 2010, 10(5), 5233-5262; doi:10.3390/s100505233
Received: 1 February 2010 / Revised: 1 April 2010 / Accepted: 14 May 2010 / Published: 25 May 2010
Cited by 7 | PDF Full-text (991 KB) | HTML Full-text | XML Full-text
Abstract
Future Wireless Sensor Networks (WSNs) will be ubiquitous, large-scale networks interconnected with the existing IP infrastructure. Autonomic functionalities have to be designed in order to reduce the complexity of their operation and management, and support the dissemination of knowledge within a WSN. In
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Future Wireless Sensor Networks (WSNs) will be ubiquitous, large-scale networks interconnected with the existing IP infrastructure. Autonomic functionalities have to be designed in order to reduce the complexity of their operation and management, and support the dissemination of knowledge within a WSN. In this paper a novel protocol for energy efficient deployment, clustering and routing in WSNs is proposed that focuses on the incorporation of autonomic functionalities in the existing approaches. The design of the protocol facilitates the design of innovative applications and services that are based on overlay topologies created through cooperation among the sensor nodes. Full article
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Open AccessArticle Basic Test Framework for the Evaluation of Text Line Segmentation and Text Parameter Extraction
Sensors 2010, 10(5), 5263-5279; doi:10.3390/s100505263
Received: 9 April 2010 / Revised: 13 May 2010 / Accepted: 14 May 2010 / Published: 25 May 2010
Cited by 20 | PDF Full-text (360 KB) | HTML Full-text | XML Full-text
Abstract
Text line segmentation is an essential stage in off-line optical character recognition (OCR) systems. It is a key because inaccurately segmented text lines will lead to OCR failure. Text line segmentation of handwritten documents is a complex and diverse problem, complicated by the
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Text line segmentation is an essential stage in off-line optical character recognition (OCR) systems. It is a key because inaccurately segmented text lines will lead to OCR failure. Text line segmentation of handwritten documents is a complex and diverse problem, complicated by the nature of handwriting. Hence, text line segmentation is a leading challenge in handwritten document image processing. Due to inconsistencies in measurement and evaluation of text segmentation algorithm quality, some basic set of measurement methods is required. Currently, there is no commonly accepted one and all algorithm evaluation is custom oriented. In this paper, a basic test framework for the evaluation of text feature extraction algorithms is proposed. This test framework consists of a few experiments primarily linked to text line segmentation, skew rate and reference text line evaluation. Although they are mutually independent, the results obtained are strongly cross linked. In the end, its suitability for different types of letters and languages as well as its adaptability are its main advantages. Thus, the paper presents an efficient evaluation method for text analysis algorithms. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Bayesian Framework for Human Body Pose Tracking from Depth Image Sequences
Sensors 2010, 10(5), 5280-5293; doi:10.3390/s100505280
Received: 7 April 2010 / Revised: 19 May 2010 / Accepted: 20 May 2010 / Published: 25 May 2010
Cited by 25 | PDF Full-text (1855 KB) | HTML Full-text | XML Full-text
Abstract
This paper addresses the problem of accurate and robust tracking of 3D human body pose from depth image sequences. Recovering the large number of degrees of freedom in human body movements from a depth image sequence is challenging due to the need to
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This paper addresses the problem of accurate and robust tracking of 3D human body pose from depth image sequences. Recovering the large number of degrees of freedom in human body movements from a depth image sequence is challenging due to the need to resolve the depth ambiguity caused by self-occlusions and the difficulty to recover from tracking failure. Human body poses could be estimated through model fitting using dense correspondences between depth data and an articulated human model (local optimization method). Although it usually achieves a high accuracy due to dense correspondences, it may fail to recover from tracking failure. Alternately, human pose may be reconstructed by detecting and tracking human body anatomical landmarks (key-points) based on low-level depth image analysis. While this method (key-point based method) is robust and recovers from tracking failure, its pose estimation accuracy depends solely on image-based localization accuracy of key-points. To address these limitations, we present a flexible Bayesian framework for integrating pose estimation results obtained by methods based on key-points and local optimization. Experimental results are shown and performance comparison is presented to demonstrate the effectiveness of the proposed approach. Full article
(This article belongs to the Special Issue Motion Detectors)

Review

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Open AccessReview Real-Time Time-Frequency Two-Dimensional Imaging of Ultrafast Transient Signals in Solid-State Organic Materials
Sensors 2010, 10(5), 4253-4269; doi:10.3390/s100504253
Received: 28 February 2010 / Revised: 18 March 2010 / Accepted: 5 April 2010 / Published: 28 April 2010
Cited by 5 | PDF Full-text (596 KB) | HTML Full-text | XML Full-text
Abstract
In this review, we demonstrate a real-time time-frequency two-dimensional (2D) pump-probe imaging spectroscopy implemented on a single shot basis applicable to excited-state dynamics in solid-state organic and biological materials. Using this technique, we could successfully map ultrafast time-frequency 2D transient absorption signals of
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In this review, we demonstrate a real-time time-frequency two-dimensional (2D) pump-probe imaging spectroscopy implemented on a single shot basis applicable to excited-state dynamics in solid-state organic and biological materials. Using this technique, we could successfully map ultrafast time-frequency 2D transient absorption signals of β-carotene in solid films with wide temporal and spectral ranges having very short accumulation time of 20 ms per unit frame. The results obtained indicate the high potential of this technique as a powerful and unique spectroscopic tool to observe ultrafast excited-state dynamics of organic and biological materials in solid-state, which undergo rapid photodegradation. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessReview Generation and Amplification of Tunable Multicolored Femtosecond Laser Pulses by Using Cascaded Four-Wave Mixing in Transparent Bulk Media
Sensors 2010, 10(5), 4296-4341; doi:10.3390/s100504296
Received: 22 January 2010 / Revised: 11 April 2010 / Accepted: 16 April 2010 / Published: 29 April 2010
Cited by 13 | PDF Full-text (2995 KB) | HTML Full-text | XML Full-text
Abstract
We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM) in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively.
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We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM) in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1) as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm) to near infrared (1.2 μm); (2) the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3) the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4) as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5) the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6) broadband two-dimensional (2-D) multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7) the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM) in conjunction with four-wave optical parametric amplification (FOPA). The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessReview Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy
Sensors 2010, 10(5), 4342-4372; doi:10.3390/s100504342
Received: 1 March 2010 / Revised: 30 March 2010 / Accepted: 9 April 2010 / Published: 29 April 2010
Cited by 30 | PDF Full-text (1089 KB) | HTML Full-text | XML Full-text
Abstract
Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the
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Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessReview Responsive Hydrogels for Label-Free Signal Transduction within Biosensors
Sensors 2010, 10(5), 4381-4409; doi:10.3390/s100504381
Received: 1 March 2010 / Revised: 12 April 2010 / Accepted: 23 April 2010 / Published: 30 April 2010
Cited by 38 | PDF Full-text (501 KB) | HTML Full-text | XML Full-text
Abstract
Hydrogels have found wide application in biosensors due to their versatile nature. This family of materials is applied in biosensing either to increase the loading capacity compared to two-dimensional surfaces, or to support biospecific hydrogel swelling occurring subsequent to specific recognition of an
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Hydrogels have found wide application in biosensors due to their versatile nature. This family of materials is applied in biosensing either to increase the loading capacity compared to two-dimensional surfaces, or to support biospecific hydrogel swelling occurring subsequent to specific recognition of an analyte. This review focuses on various principles underpinning the design of biospecific hydrogels acting through various molecular mechanisms in transducing the recognition event of label-free analytes. Towards this end, we describe several promising hydrogel systems that when combined with the appropriate readout platform and quantitative approach could lead to future real-life applications. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessReview Measurement Uncertainty Estimation in Amperometric Sensors: A Tutorial Review
Sensors 2010, 10(5), 4430-4455; doi:10.3390/s100504430
Received: 26 February 2010 / Revised: 29 March 2010 / Accepted: 10 April 2010 / Published: 30 April 2010
Cited by 13 | PDF Full-text (295 KB) | HTML Full-text | XML Full-text
Abstract
This tutorial focuses on measurement uncertainty estimation in amperometric sensors (both for liquid and gas-phase measurements). The main uncertainty sources are reviewed and their contributions are discussed with relation to the principles of operation of the sensors, measurement conditions and properties of the
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This tutorial focuses on measurement uncertainty estimation in amperometric sensors (both for liquid and gas-phase measurements). The main uncertainty sources are reviewed and their contributions are discussed with relation to the principles of operation of the sensors, measurement conditions and properties of the measured samples. The discussion is illustrated by case studies based on the two major approaches for uncertainty evaluation–the ISO GUM modeling approach and the Nordtest approach. This tutorial is expected to be of interest to workers in different fields of science who use measurements with amperometric sensors and need to evaluate the uncertainty of the obtained results but are new to the concept of measurement uncertainty. The tutorial is also expected to be educative in order to make measurement results more accurate. Full article
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Open AccessReview Design Strategies for Aptamer-Based Biosensors
Sensors 2010, 10(5), 4541-4557; doi:10.3390/s100504541
Received: 11 February 2010 / Revised: 1 April 2010 / Accepted: 4 April 2010 / Published: 4 May 2010
Cited by 57 | PDF Full-text (708 KB) | HTML Full-text | XML Full-text
Abstract
Aptamers have been widely used as recognition elements for biosensor construction, especially in the detection of proteins or small molecule targets, and regarded as promising alternatives for antibodies in bioassay areas. In this review, we present an overview of reported design strategies for
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Aptamers have been widely used as recognition elements for biosensor construction, especially in the detection of proteins or small molecule targets, and regarded as promising alternatives for antibodies in bioassay areas. In this review, we present an overview of reported design strategies for the fabrication of biosensors and classify them into four basic modes: target-induced structure switching mode, sandwich or sandwich-like mode, target-induced dissociation/displacement mode and competitive replacement mode. In view of the unprecedented advantages brought about by aptamers and smart design strategies, aptamer-based biosensors are expected to be one of the most promising devices in bioassay related applications. Full article
(This article belongs to the Section Biosensors)
Open AccessReview Glucose Biosensors: An Overview of Use in Clinical Practice
Sensors 2010, 10(5), 4558-4576; doi:10.3390/s100504558
Received: 11 February 2010 / Revised: 18 March 2010 / Accepted: 22 April 2010 / Published: 4 May 2010
Cited by 196 | PDF Full-text (266 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Blood glucose monitoring has been established as a valuable tool in the management of diabetes. Since maintaining normal blood glucose levels is recommended, a series of suitable glucose biosensors have been developed. During the last 50 years, glucose biosensor technology including point-of-care devices,
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Blood glucose monitoring has been established as a valuable tool in the management of diabetes. Since maintaining normal blood glucose levels is recommended, a series of suitable glucose biosensors have been developed. During the last 50 years, glucose biosensor technology including point-of-care devices, continuous glucose monitoring systems and noninvasive glucose monitoring systems has been significantly improved. However, there continues to be several challenges related to the achievement of accurate and reliable glucose monitoring. Further technical improvements in glucose biosensors, standardization of the analytical goals for their performance, and continuously assessing and training lay users are required. This article reviews the brief history, basic principles, analytical performance, and the present status of glucose biosensors in the clinical practice. Full article
(This article belongs to the Special Issue Glucose Sensors)
Open AccessReview Privacy-Preserving Data Aggregation Protocols for Wireless Sensor Networks: A Survey
Sensors 2010, 10(5), 4577-4601; doi:10.3390/s100504577
Received: 10 March 2010 / Revised: 6 April 2010 / Accepted: 28 April 2010 / Published: 4 May 2010
Cited by 18 | PDF Full-text (829 KB) | HTML Full-text | XML Full-text
Abstract
Many wireless sensor network (WSN) applications require privacy-preserving aggregation of sensor data during transmission from the source nodes to the sink node. In this paper, we explore several existing privacy-preserving data aggregation (PPDA) protocols for WSNs in order to provide some insights on
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Many wireless sensor network (WSN) applications require privacy-preserving aggregation of sensor data during transmission from the source nodes to the sink node. In this paper, we explore several existing privacy-preserving data aggregation (PPDA) protocols for WSNs in order to provide some insights on their current status. For this, we evaluate the PPDA protocols on the basis of such metrics as communication and computation costs in order to demonstrate their potential for supporting privacy-preserving data aggregation in WSNs. In addition, based on the existing research, we enumerate some important future research directions in the field of privacy-preserving data aggregation for WSNs. Full article
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Open AccessReview A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides
Sensors 2010, 10(5), 4855-4886; doi:10.3390/s100504855
Received: 11 March 2010 / Revised: 7 April 2010 / Accepted: 15 April 2010 / Published: 12 May 2010
Cited by 232 | PDF Full-text (656 KB) | HTML Full-text | XML Full-text
Abstract
Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation.
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Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessReview Effect of Atmospheric Conditions on LIBS Spectra
Sensors 2010, 10(5), 4907-4925; doi:10.3390/s100504907
Received: 30 March 2010 / Revised: 4 May 2010 / Accepted: 10 May 2010 / Published: 14 May 2010
Cited by 63 | PDF Full-text (1294 KB) | HTML Full-text | XML Full-text
Abstract
Laser-induced breakdown spectroscopy (LIBS) is typically performed at ambient Earth atmospheric conditions. However, interest in LIBS in other atmospheric conditions has increased in recent years, especially for use in space exploration (e.g., Mars and Lunar) or to improve resolution for isotopic signatures. This
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Laser-induced breakdown spectroscopy (LIBS) is typically performed at ambient Earth atmospheric conditions. However, interest in LIBS in other atmospheric conditions has increased in recent years, especially for use in space exploration (e.g., Mars and Lunar) or to improve resolution for isotopic signatures. This review focuses on what has been reported about the performance of LIBS in reduced pressure environments as well as in various gases other than air. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessReview Transcriptional Regulation of Glucose Sensors in Pancreatic β-Cells and Liver: An Update
Sensors 2010, 10(5), 5031-5053; doi:10.3390/s100505031
Received: 1 February 2010 / Revised: 7 May 2010 / Accepted: 13 May 2010 / Published: 19 May 2010
Cited by 7 | PDF Full-text (709 KB) | HTML Full-text | XML Full-text
Abstract
Pancreatic β-cells and the liver play a key role in glucose homeostasis. After a meal or in a state of hyperglycemia, glucose is transported into the β-cells or hepatocytes where it is metabolized. In the β-cells, glucose is metabolized to increase the ATP:ADP
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Pancreatic β-cells and the liver play a key role in glucose homeostasis. After a meal or in a state of hyperglycemia, glucose is transported into the β-cells or hepatocytes where it is metabolized. In the β-cells, glucose is metabolized to increase the ATP:ADP ratio, resulting in the secretion of insulin stored in the vesicle. In the hepatocytes, glucose is metabolized to CO2, fatty acids or stored as glycogen. In these cells, solute carrier family 2 (SLC2A2) and glucokinase play a key role in sensing and uptaking glucose. Dysfunction of these proteins results in the hyperglycemia which is one of the characteristics of type 2 diabetes mellitus (T2DM). Thus, studies on the molecular mechanisms of their transcriptional regulations are important in understanding pathogenesis and combating T2DM. In this paper, we will review a recent update on the progress of gene regulation of glucose sensors in the liver and β-cells. Full article
(This article belongs to the Section Biosensors)
Open AccessReview Sonochemically Fabricated Microelectrode Arrays for Use as Sensing Platforms
Sensors 2010, 10(5), 5090-5132; doi:10.3390/s100505090
Received: 26 January 2010 / Revised: 15 April 2010 / Accepted: 27 April 2010 / Published: 25 May 2010
Cited by 4 | PDF Full-text (1301 KB) | HTML Full-text | XML Full-text
Abstract
The development, manufacture, modification and subsequent utilisation of sonochemically-formed microelectrode arrays is described for a range of applications. Initial fabrication of the sensing platform utilises ultrasonic ablation of electrochemically insulating polymers deposited upon conductive carbon substrates, forming an array of up to 70,000
[...] Read more.
The development, manufacture, modification and subsequent utilisation of sonochemically-formed microelectrode arrays is described for a range of applications. Initial fabrication of the sensing platform utilises ultrasonic ablation of electrochemically insulating polymers deposited upon conductive carbon substrates, forming an array of up to 70,000 microelectrode pores cm–2. Electrochemical and optical analyses using these arrays, their enhanced signal response and stir-independence area are all discussed. The growth of conducting polymeric “mushroom” protrusion arrays with entrapped biological entities, thereby forming biosensors is detailed. The simplicity and inexpensiveness of this approach, lending itself ideally to mass fabrication coupled with unrivalled sensitivity and stir independence makes commercial viability of this process a reality. Application of microelectrode arrays as functional components within sensors include devices for detection of chlorine, glucose, ethanol and pesticides. Immunosensors based on microelectrode arrays are described within this monograph for antigens associated with prostate cancer and transient ischemic attacks (strokes). Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
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Open AccessReview Carbon Nanostructure-Based Field-Effect Transistors for Label-Free Chemical/Biological Sensors
Sensors 2010, 10(5), 5133-5159; doi:10.3390/s100505133
Received: 23 March 2010 / Revised: 15 April 2010 / Accepted: 5 May 2010 / Published: 25 May 2010
Cited by 65 | PDF Full-text (887 KB) | HTML Full-text | XML Full-text
Abstract
Over the past decade, electrical detection of chemical and biological species using novel nanostructure-based devices has attracted significant attention for chemical, genomics, biomedical diagnostics, and drug discovery applications. The use of nanostructured devices in chemical/biological sensors in place of conventional sensing technologies has
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Over the past decade, electrical detection of chemical and biological species using novel nanostructure-based devices has attracted significant attention for chemical, genomics, biomedical diagnostics, and drug discovery applications. The use of nanostructured devices in chemical/biological sensors in place of conventional sensing technologies has advantages of high sensitivity, low decreased energy consumption and potentially highly miniaturized integration. Owing to their particular structure, excellent electrical properties and high chemical stability, carbon nanotube and graphene based electrical devices have been widely developed for high performance label-free chemical/biological sensors. Here, we review the latest developments of carbon nanostructure-based transistor sensors in ultrasensitive detection of chemical/biological entities, such as poisonous gases, nucleic acids, proteins and cells. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
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Open AccessReview Location Estimation in Wireless Sensor Networks Using Spring-Relaxation Technique
Sensors 2010, 10(5), 5171-5192; doi:10.3390/s100505171
Received: 25 March 2010 / Revised: 15 April 2010 / Accepted: 10 May 2010 / Published: 25 May 2010
Cited by 12 | PDF Full-text (327 KB) | HTML Full-text | XML Full-text
Abstract
Accurate and low-cost autonomous self-localization is a critical requirement of various applications of a large-scale distributed wireless sensor network (WSN). Due to its massive deployment of sensors, explicit measurements based on specialized localization hardware such as the Global Positioning System (GPS) is not
[...] Read more.
Accurate and low-cost autonomous self-localization is a critical requirement of various applications of a large-scale distributed wireless sensor network (WSN). Due to its massive deployment of sensors, explicit measurements based on specialized localization hardware such as the Global Positioning System (GPS) is not practical. In this paper, we propose a low-cost WSN localization solution. Our design uses received signal strength indicators for ranging, light weight distributed algorithms based on the spring-relaxation technique for location computation, and the cooperative approach to achieve certain location estimation accuracy with a low number of nodes with known locations. We provide analysis to show the suitability of the spring-relaxation technique for WSN localization with cooperative approach, and perform simulation experiments to illustrate its accuracy in localization. Full article
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Open AccessCorrection Correction: Chang, C.W., et al. Development of a Three Dimensional Neural Sensing Device by a Stacking Method. Sensors 2010, 10, 4238-4252
Sensors 2010, 10(5), 4716; doi:10.3390/s100504716
Received: 6 March 2010 / Published: 7 May 2010
PDF Full-text (30 KB) | HTML Full-text | XML Full-text
Abstract The authors would like to correct the affiliations and acknowledgement of this paper [1] as follows: [...] Full article
(This article belongs to the Special Issue Bio-devices and Materials)

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