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Sensors, Volume 10, Issue 3 (March 2010) , Pages 1423-2459

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Open AccessArticle Cryptanalysis and Security Improvements of ‘Two-Factor User Authentication in Wireless Sensor Networks’
Sensors 2010, 10(3), 2450-2459; https://doi.org/10.3390/s100302450
Received: 5 January 2010 / Revised: 4 March 2010 / Accepted: 12 March 2010 / Published: 23 March 2010
Cited by 201 | Viewed by 8684 | PDF Full-text (76 KB) | HTML Full-text | XML Full-text
Abstract
User authentication in wireless sensor networks (WSN) is a critical security issue due to their unattended and hostile deployment in the field. Since sensor nodes are equipped with limited computing power, storage, and communication modules; authenticating remote users in such resource-constrained environments is
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User authentication in wireless sensor networks (WSN) is a critical security issue due to their unattended and hostile deployment in the field. Since sensor nodes are equipped with limited computing power, storage, and communication modules; authenticating remote users in such resource-constrained environments is a paramount security concern. Recently, M.L. Das proposed a two-factor user authentication scheme in WSNs and claimed that his scheme is secure against different kinds of attack. However, in this paper, we show that the M.L. Das-scheme has some critical security pitfalls and cannot be recommended for real applications. We point out that in his scheme: users cannot change/update their passwords, it does not provide mutual authentication between gateway node and sensor node, and is vulnerable to gateway node bypassing attack and privileged-insider attack. To overcome the inherent security weaknesses of the M.L. Das-scheme, we propose improvements and security patches that attempt to fix the susceptibilities of his scheme. The proposed security improvements can be incorporated in the M.L. Das-scheme for achieving a more secure and robust two-factor user authentication in WSNs. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Near-Infrared Fluorescence Detection of Acetylcholine in Aqueous Solution Using a Complex of Rhodamine 800 and p-Sulfonato-calix[8]arene
Sensors 2010, 10(3), 2438-2449; https://doi.org/10.3390/s100302438
Received: 18 February 2010 / Revised: 4 March 2010 / Accepted: 9 March 2010 / Published: 23 March 2010
Cited by 26 | Viewed by 6623 | PDF Full-text (641 KB) | HTML Full-text | XML Full-text
Abstract
The complexing properties of p-sulfonatocalix[n]arenes (n = 4: S[4], n = 6: S[6], and n = 8: S[8]) for rhodamine 800 (Rh800) and indocyanine green (ICG) were examined to develop a near-infrared (NIR) fluorescence detection method for acetylcholine (ACh). We found that
[...] Read more.
The complexing properties of p-sulfonatocalix[n]arenes (n = 4: S[4], n = 6: S[6], and n = 8: S[8]) for rhodamine 800 (Rh800) and indocyanine green (ICG) were examined to develop a near-infrared (NIR) fluorescence detection method for acetylcholine (ACh). We found that Rh800 (as a cation) forms an inclusion complex with S[n], while ICG (as a twitter ion) have no binding ability for S[n]. The binding ability of Rh800 to S[n] decreased in the order of S[8] > S[6] >> S[4]. By the formation of the complex between Rh800 and S[8], fluorescence intensity of the Rh800 was significantly decreased. From the fluorescence titration of Rh800 by S[8], stoichiometry of the Rh800-S[8] complex was determined to be 1:1 with a dissociation constant of 2.2 mM in PBS. The addition of ACh to the aqueous solution of the Rh800-S[8] complex caused a fluorescence increase of Rh800, resulting from a competitive replacement of Rh800 by ACh in the complex. From the fluorescence change by the competitive fluorophore replacement, stoichiometry of the Rh800-ACh complex was found to be 1:1 with a dissociation constant of 1.7 mM. The effects of other neurotransmitters on the fluorescence spectra of the Rh800-S[8] complex were examined for dopamine, GABA, glycine, and L-asparatic acid. Among the neurotransmitters examined, fluorescence response of the Rh800-S[8] complex was highly specific to ACh. Rh800-S[8] complexes can be used as a NIR fluorescent probe for the detection of ACh (5 × 10-4−10-3 M) in PBS buffer (pH = 7.2). Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
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Open AccessArticle Dynamical Jumping Real-Time Fault-Tolerant Routing Protocol for Wireless Sensor Networks
Sensors 2010, 10(3), 2416-2437; https://doi.org/10.3390/s100302416
Received: 26 January 2010 / Revised: 3 March 2010 / Accepted: 10 March 2010 / Published: 23 March 2010
Cited by 19 | Viewed by 8257 | PDF Full-text (317 KB) | HTML Full-text | XML Full-text
Abstract
In time-critical wireless sensor network (WSN) applications, a high degree of reliability is commonly required. A dynamical jumping real-time fault-tolerant routing protocol (DMRF) is proposed in this paper. Each node utilizes the remaining transmission time of the data packets and the state of
[...] Read more.
In time-critical wireless sensor network (WSN) applications, a high degree of reliability is commonly required. A dynamical jumping real-time fault-tolerant routing protocol (DMRF) is proposed in this paper. Each node utilizes the remaining transmission time of the data packets and the state of the forwarding candidate node set to dynamically choose the next hop. Once node failure, network congestion or void region occurs, the transmission mode will switch to jumping transmission mode, which can reduce the transmission time delay, guaranteeing the data packets to be sent to the destination node within the specified time limit. By using feedback mechanism, each node dynamically adjusts the jumping probabilities to increase the ratio of successful transmission. Simulation results show that DMRF can not only efficiently reduce the effects of failure nodes, congestion and void region, but also yield higher ratio of successful transmission, smaller transmission delay and reduced number of control packets. Full article
Open AccessReview Stress Sensors and Signal Transducers in Cyanobacteria
Sensors 2010, 10(3), 2386-2415; https://doi.org/10.3390/s100302386
Received: 20 January 2010 / Revised: 15 February 2010 / Accepted: 3 March 2010 / Published: 23 March 2010
Cited by 75 | Viewed by 11354 | PDF Full-text (403 KB) | HTML Full-text | XML Full-text
Abstract
In living cells, the perception of environmental stress and the subsequent transduction of stress signals are primary events in the acclimation to changes in the environment. Some molecular sensors and transducers of environmental stress cannot be identified by traditional and conventional methods. Based
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In living cells, the perception of environmental stress and the subsequent transduction of stress signals are primary events in the acclimation to changes in the environment. Some molecular sensors and transducers of environmental stress cannot be identified by traditional and conventional methods. Based on genomic information, a systematic approach has been applied to the solution of this problem in cyanobacteria, involving mutagenesis of potential sensors and signal transducers in combination with DNA microarray analyses for the genome-wide expression of genes. Forty-five genes for the histidine kinases (Hiks), 12 genes for serine-threonine protein kinases (Spks), 42 genes for response regulators (Rres), seven genes for RNA polymerase sigma factors, and nearly 70 genes for transcription factors have been successfully inactivated by targeted mutagenesis in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Screening of mutant libraries by genome-wide DNA microarray analysis under various stress and non-stress conditions has allowed identification of proteins that perceive and transduce signals of environmental stress. Here we summarize recent progress in the identification of sensory and regulatory systems, including Hiks, Rres, Spks, sigma factors, transcription factors, and the role of genomic DNA supercoiling in the regulation of the responses of cyanobacterial cells to various types of stress. Full article
(This article belongs to the Special Issue Advances in Transducers)
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Open AccessArticle Ambient Intelligence Systems for Personalized Sport Training
Sensors 2010, 10(3), 2359-2385; https://doi.org/10.3390/s100302359
Received: 22 January 2010 / Revised: 3 March 2010 / Accepted: 10 March 2010 / Published: 22 March 2010
Cited by 33 | Viewed by 12480 | PDF Full-text (6011 KB) | HTML Full-text | XML Full-text
Abstract
Several research programs are tackling the use of Wireless Sensor Networks (WSN) at specific fields, such as e-Health, e-Inclusion or e-Sport. This is the case of the project “Ambient Intelligence Systems Support for Athletes with Specific Profiles”, which intends to assist athletes in
[...] Read more.
Several research programs are tackling the use of Wireless Sensor Networks (WSN) at specific fields, such as e-Health, e-Inclusion or e-Sport. This is the case of the project “Ambient Intelligence Systems Support for Athletes with Specific Profiles”, which intends to assist athletes in their training. In this paper, the main developments and outcomes from this project are described. The architecture of the system comprises a WSN deployed in the training area which provides communication with athletes’ mobile equipments, performs location tasks, and harvests environmental data (wind speed, temperature, etc.). Athletes are equipped with a monitoring unit which obtains data from their training (pulse, speed, etc.). Besides, a decision engine combines these real-time data together with static information about the training field, and from the athlete, to direct athletes’ training to fulfill some specific goal. A prototype is presented in this work for a cross country running scenario, where the objective is to maintain the heart rate (HR) of the runner in a target range. For each track, the environmental conditions (temperature of the next track), the current athlete condition (HR), and the intrinsic difficulty of the track (slopes) influence the performance of the athlete. The decision engine, implemented by means of (m; s)-splines interpolation, estimates the future HR and selects the best track in each fork of the circuit. This method achieves a success ratio in the order of 80%. Indeed, results demonstrate that if environmental information is not take into account to derive training orders, the success ratio is reduced notably. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Refractive Index Sensor Based on a 1D Photonic Crystal in a Microfluidic Channel
Sensors 2010, 10(3), 2348-2358; https://doi.org/10.3390/s100302348
Received: 27 January 2010 / Revised: 10 February 2010 / Accepted: 5 March 2010 / Published: 22 March 2010
Cited by 22 | Viewed by 6128 | PDF Full-text (1313 KB) | HTML Full-text | XML Full-text
Abstract
A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with
[...] Read more.
A refractive index sensor has been fabricated in silicon oxynitride by standard UV lithography and dry etching processes. The refractive index sensor consists of a 1D photonic crystal (PhC) embedded in a microfluidic channel addressed by fiber-terminated planar waveguides. Experimental demonstrations performed with several ethanol solutions ranging from a purity of 96.00% (n = 1.36356) to 95.04% (n = 1.36377) yielded a sensitivity (Δλ/Δn) of 836 nm/RIU and a limit of detection (LOD) of 6 x 10-5 RIU, which is, however, still one order of magnitude higher than the theoretical lower limit of the limit of detection 1.3 x 10–6 RIU. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
Open AccessArticle An Adaptive Fault-Tolerant Event Detection Scheme for Wireless Sensor Networks
Sensors 2010, 10(3), 2332-2347; https://doi.org/10.3390/s100302332
Received: 20 January 2010 / Revised: 25 February 2010 / Accepted: 10 March 2010 / Published: 19 March 2010
Cited by 33 | Viewed by 6169 | PDF Full-text (576 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we present an adaptive fault-tolerant event detection scheme for wireless sensor networks. Each sensor node detects an event locally in a distributed manner by using the sensor readings of its neighboring nodes. Confidence levels of sensor nodes are used to
[...] Read more.
In this paper, we present an adaptive fault-tolerant event detection scheme for wireless sensor networks. Each sensor node detects an event locally in a distributed manner by using the sensor readings of its neighboring nodes. Confidence levels of sensor nodes are used to dynamically adjust the threshold for decision making, resulting in consistent performance even with increasing number of faulty nodes. In addition, the scheme employs a moving average filter to tolerate most transient faults in sensor readings, reducing the effective fault probability. Only three bits of data are exchanged to reduce the communication overhead in detecting events. Simulation results show that event detection accuracy and false alarm rate are kept very high and low, respectively, even in the case where 50% of the sensor nodes are faulty. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Fluorescent Silicate Materials for the Detection of Paraoxon
Sensors 2010, 10(3), 2315-2331; https://doi.org/10.3390/s100302315
Received: 4 January 2010 / Revised: 2 March 2010 / Accepted: 8 March 2010 / Published: 19 March 2010
Cited by 25 | Viewed by 9973 | PDF Full-text (343 KB) | HTML Full-text | XML Full-text
Abstract
Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the
[...] Read more.
Porphyrins are a family of highly conjugated molecules that strongly absorb visible light and fluoresce intensely. These molecules are sensitive to changes in their immediate environment and have been widely described for optical detection applications. Surfactant-templated organosilicate materials have been described for the semi-selective adsorption of small molecule contaminants. These structures offer high surface areas and large pore volumes within an organized framework. The organic bridging groups in the materials can be altered to provide varied binding characteristics. This effort seeks to utilize the tunable binding selectivity, high surface area, and low materials density of these highly ordered pore networks and to combine them with the unique spectrophotometric properties of porphyrins. In the porphyrin-embedded materials (PEMs), the organosilicate scaffold stabilizes the porphyrin and facilitates optimal orientation of porphyrin and target. The materials can be stored under ambient conditions and offer exceptional shelf-life. Here, we report on the design of PEMs with specificity for organophosphates and compounds of similar structure. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
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Open AccessArticle Decentralized Sensor Fusion for Ubiquitous Networking Robotics in Urban Areas
Sensors 2010, 10(3), 2274-2314; https://doi.org/10.3390/s100302274
Received: 12 January 2010 / Revised: 2 February 2010 / Accepted: 28 February 2010 / Published: 19 March 2010
Cited by 34 | Viewed by 9736 | PDF Full-text (2328 KB) | HTML Full-text | XML Full-text
Abstract
In this article we explain the architecture for the environment and sensors that has been built for the European project URUS (Ubiquitous Networking Robotics in Urban Sites), a project whose objective is to develop an adaptable network robot architecture for cooperation between network
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In this article we explain the architecture for the environment and sensors that has been built for the European project URUS (Ubiquitous Networking Robotics in Urban Sites), a project whose objective is to develop an adaptable network robot architecture for cooperation between network robots and human beings and/or the environment in urban areas. The project goal is to deploy a team of robots in an urban area to give a set of services to a user community. This paper addresses the sensor architecture devised for URUS and the type of robots and sensors used, including environment sensors and sensors onboard the robots. Furthermore, we also explain how sensor fusion takes place to achieve urban outdoor execution of robotic services. Finally some results of the project related to the sensor network are highlighted. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
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Open AccessArticle Organic ISFET Based on Poly (3-hexylthiophene)
Sensors 2010, 10(3), 2262-2273; https://doi.org/10.3390/s100302262
Received: 24 January 2010 / Revised: 13 February 2010 / Accepted: 10 March 2010 / Published: 19 March 2010
Cited by 27 | Viewed by 5903 | PDF Full-text (1367 KB) | HTML Full-text | XML Full-text
Abstract
We have fabricated organic field-effect transistors (OFETs) with regioregular poly(3-hexylthiophene) (P3HT) operable at low-voltages in liquid solutions, suitable for in vitro biosensing applications. Measurements in electrolytes have shown that the performance of the transistors did not deteriorate and they can be directly used
[...] Read more.
We have fabricated organic field-effect transistors (OFETs) with regioregular poly(3-hexylthiophene) (P3HT) operable at low-voltages in liquid solutions, suitable for in vitro biosensing applications. Measurements in electrolytes have shown that the performance of the transistors did not deteriorate and they can be directly used as ionsensitive transducers. Furthermore, more complex media have been tested, with the perspective of cell analysis. Degradation effects acting on the device operating in liquid could be partly compensated by adopting an alternate current measuring mode. Full article
(This article belongs to the Special Issue ISFET Sensors)
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Open AccessArticle Efficiency of Event-Based Sampling According to Error Energy Criterion
Sensors 2010, 10(3), 2242-2261; https://doi.org/10.3390/s100302242
Received: 23 December 2009 / Revised: 5 February 2010 / Accepted: 24 February 2010 / Published: 18 March 2010
Cited by 26 | Viewed by 7949 | PDF Full-text (231 KB) | HTML Full-text | XML Full-text
Abstract
The paper belongs to the studies that deal with the effectiveness of the particular event-based sampling scheme compared to the conventional periodic sampling as a reference. In the present study, the event-based sampling according to a constant energy of sampling error is analyzed.
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The paper belongs to the studies that deal with the effectiveness of the particular event-based sampling scheme compared to the conventional periodic sampling as a reference. In the present study, the event-based sampling according to a constant energy of sampling error is analyzed. This criterion is suitable for applications where the energy of sampling error should be bounded (i.e., in building automation, or in greenhouse climate monitoring and control). Compared to the integral sampling criteria, the error energy criterion gives more weight to extreme sampling error values. The proposed sampling principle extends a range of event-based sampling schemes and makes the choice of particular sampling criterion more flexible to application requirements. In the paper, it is proved analytically that the proposed event-based sampling criterion is more effective than the periodic sampling by a factor defined by the ratio of the maximum to the mean of the cubic root of the signal time-derivative square in the analyzed time interval. Furthermore, it is shown that the sampling according to energy criterion is less effective than the send-on-delta scheme but more effective than the sampling according to integral criterion. On the other hand, it is indicated that higher effectiveness in sampling according to the selected event-based criterion is obtained at the cost of increasing the total sampling error defined as the sum of errors for all the samples taken. Full article
Open AccessArticle A Deployment of Fine-Grained Sensor Network and Empirical Analysis of Urban Temperature
Sensors 2010, 10(3), 2217-2241; https://doi.org/10.3390/s100302217
Received: 15 January 2010 / Revised: 20 February 2010 / Accepted: 15 March 2010 / Published: 18 March 2010
Cited by 14 | Viewed by 7554 | PDF Full-text (3008 KB) | HTML Full-text | XML Full-text
Abstract
Temperature in an urban area exhibits a complicated pattern due to complexity of infrastructure. Despite geographical proximity, structures of a group of buildings and streets affect changes in temperature. To investigate the pattern of fine-grained distribution of temperature, we installed a densely distributed
[...] Read more.
Temperature in an urban area exhibits a complicated pattern due to complexity of infrastructure. Despite geographical proximity, structures of a group of buildings and streets affect changes in temperature. To investigate the pattern of fine-grained distribution of temperature, we installed a densely distributed sensor network called UScan. In this paper, we describe the system architecture of UScan as well as experience learned from installing 200 sensors in downtown Tokyo. The field experiment of UScan system operated for two months to collect long-term urban temperature data. To analyze the collected data in an efficient manner, we propose a lightweight clustering methodology to study the correlation between the pattern of temperature and various environmental factors including the amount of sunshine, the width of streets, and the existence of trees. The analysis reveals meaningful results and asserts the necessity of fine-grained deployment of sensors in an urban area. Full article
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Open AccessArticle Effect of Silver Annealing Conditions on the Performance of Electrolytic Silver/Silver Chloride Electrodes used in Harned Cell Measurements of pH
Sensors 2010, 10(3), 2202-2216; https://doi.org/10.3390/s100302202
Received: 22 February 2010 / Revised: 5 March 2010 / Accepted: 16 March 2010 / Published: 17 March 2010
Cited by 9 | Viewed by 6161 | PDF Full-text (2646 KB) | HTML Full-text | XML Full-text
Abstract
We have studied the long and short term stability of electrolytic Ag/AgCl electrodes fabricated from Ag wire that has been subjected to a range of different annealing conditions. At elevated temperatures, the presence of oxygen during the annealing process has been shown to
[...] Read more.
We have studied the long and short term stability of electrolytic Ag/AgCl electrodes fabricated from Ag wire that has been subjected to a range of different annealing conditions. At elevated temperatures, the presence of oxygen during the annealing process has been shown to be detrimental to the performance of electrodes produced. This phenomenon has been attributed to the dissolution of oxygen in the Ag lattice leading to structural changes in the Ag/AgCl electrode material. Electrodes prepared from Ag wire annealed in the absence of oxygen have shown no appreciable change in performance throughout the temperature range employed. This work has resulted in an improved understanding of the optimum annealing conditions required for Ag used in the preparation of electrolytic Ag/AgCl reference electrodes. This work has positive implications for the accuracy of Harned cell measurements of pH. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Virtual Sensor for Failure Detection, Identification and Recovery in the Transition Phase of a Morphing Aircraft
Sensors 2010, 10(3), 2188-2201; https://doi.org/10.3390/s100302188
Received: 7 January 2010 / Revised: 19 February 2010 / Accepted: 21 February 2010 / Published: 17 March 2010
Cited by 22 | Viewed by 6809 | PDF Full-text (368 KB) | HTML Full-text | XML Full-text
Abstract
The Helicopter Adaptive Aircraft (HADA) is a morphing aircraft which is able to take-off as a helicopter and, when in forward flight, unfold the wings that are hidden under the fuselage, and transfer the power from the main rotor to a propeller, thus
[...] Read more.
The Helicopter Adaptive Aircraft (HADA) is a morphing aircraft which is able to take-off as a helicopter and, when in forward flight, unfold the wings that are hidden under the fuselage, and transfer the power from the main rotor to a propeller, thus morphing from a helicopter to an airplane. In this process, the reliable folding and unfolding of the wings is critical, since a failure may determine the ability to perform a mission, and may even be catastrophic. This paper proposes a virtual sensor based Fault Detection, Identification and Recovery (FDIR) system to increase the reliability of the HADA aircraft. The virtual sensor is able to capture the nonlinear interaction between the folding/unfolding wings aerodynamics and the HADA airframe using the navigation sensor measurements. The proposed FDIR system has been validated using a simulation model of the HADA aircraft, which includes real phenomena as sensor noise and sampling characteristics and turbulence and wind perturbations. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy
Sensors 2010, 10(3), 2169-2187; https://doi.org/10.3390/s100302169
Received: 18 January 2010 / Revised: 2 March 2010 / Accepted: 10 March 2010 / Published: 16 March 2010
Cited by 8 | Viewed by 6601 | PDF Full-text (338 KB) | HTML Full-text | XML Full-text
Abstract
The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable
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The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microwave spectroscopy and their role in the determination of magnetic moments and excited state lifetimes. Also, the trap-assisted measurement of radiative nuclear de-excitations in the X-ray domain is discussed. This way, the different applications range over more than 12 orders of magnitude in the detectable photon energies, from below μeV in the microwave domain to beyond MeV in the X-ray domain. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle Data Driven Performance Evaluation of Wireless Sensor Networks
Sensors 2010, 10(3), 2150-2168; https://doi.org/10.3390/s100302150
Received: 3 February 2010 / Revised: 22 February 2010 / Accepted: 12 March 2010 / Published: 16 March 2010
Cited by 10 | Viewed by 10456 | PDF Full-text (868 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks are presented as devices for signal sampling and reconstruction. Within this framework, the qualitative and quantitative influence of (i) signal granularity, (ii) spatial distribution of sensors, (iii) sensors clustering, and (iv) signal reconstruction procedure are assessed. This is done by
[...] Read more.
Wireless Sensor Networks are presented as devices for signal sampling and reconstruction. Within this framework, the qualitative and quantitative influence of (i) signal granularity, (ii) spatial distribution of sensors, (iii) sensors clustering, and (iv) signal reconstruction procedure are assessed. This is done by defining an error metric and performing a Monte Carlo experiment. It is shown that all these factors have significant impact on the quality of the reconstructed signal. The extent of such impact is quantitatively assessed. Full article
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Open AccessArticle Real-Time Estimation of Pathological Tremor Parameters from Gyroscope Data
Sensors 2010, 10(3), 2129-2149; https://doi.org/10.3390/s100302129
Received: 25 January 2010 / Revised: 26 February 2010 / Accepted: 1 March 2010 / Published: 16 March 2010
Cited by 51 | Viewed by 9607 | PDF Full-text (1176 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a two stage algorithm for real-time estimation of instantaneous tremor parameters from gyroscope recordings. Gyroscopes possess the advantage of providing directly joint rotational speed, overcoming the limitations of traditional tremor recording based on accelerometers. The proposed algorithm first extracts tremor
[...] Read more.
This paper presents a two stage algorithm for real-time estimation of instantaneous tremor parameters from gyroscope recordings. Gyroscopes possess the advantage of providing directly joint rotational speed, overcoming the limitations of traditional tremor recording based on accelerometers. The proposed algorithm first extracts tremor patterns from raw angular data, and afterwards estimates its instantaneous amplitude and frequency. Real-time separation of voluntary and tremorous motion relies on their different frequency contents, whereas tremor modelling is based on an adaptive LMS algorithm and a Kalman filter. Tremor parameters will be employed to drive a neuroprosthesis for tremor suppression based on biomechanical loading. Full article
(This article belongs to the Special Issue Motion Detectors)
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Open AccessArticle Immobilization of Acetylcholinesterase on Screen-Printed Electrodes. Application to the Determination of Arsenic(III)
Sensors 2010, 10(3), 2119-2128; https://doi.org/10.3390/s100302119
Received: 29 December 2009 / Revised: 8 February 2010 / Accepted: 24 February 2010 / Published: 16 March 2010
Cited by 37 | Viewed by 6958 | PDF Full-text (212 KB) | HTML Full-text | XML Full-text
Abstract
Enzymatic amperometric procedures for measuring arsenic, based on the inhibitive action of this metal on acetylcholinesterase enzyme activity, have been developed. Screen-printed carbon electrodes (SPCEs) were used with acetylcholinesterase covalently bonded directly to its surface. The amperometric response of acetylcholinesterase was affected by
[...] Read more.
Enzymatic amperometric procedures for measuring arsenic, based on the inhibitive action of this metal on acetylcholinesterase enzyme activity, have been developed. Screen-printed carbon electrodes (SPCEs) were used with acetylcholinesterase covalently bonded directly to its surface. The amperometric response of acetylcholinesterase was affected by the presence of arsenic ions, which caused a decrease in the current intensity. The experimental optimum working conditions of pH, substrate concentration and potential applied, were established. Under these conditions, repeatability and reproducibility of biosensors were determined, reaching values below 4% in terms of relative standard deviation. The detection limit obtained for arsenic was 1.1 × 10−8 M for Ach/SPCE biosensor. Analysis of the possible effect of the presence of foreign ions in the solution was performed. The method was applied to determine levels of arsenic in spiked tap water samples. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Quantitative Determination of Fibrinogen of Patients with Coronary Heart Diseases through Piezoelectric Agglutination Sensor
Sensors 2010, 10(3), 2107-2118; https://doi.org/10.3390/s100302107
Received: 8 January 2010 / Revised: 8 February 2010 / Accepted: 1 March 2010 / Published: 16 March 2010
Cited by 1 | Viewed by 7319 | PDF Full-text (392 KB) | HTML Full-text | XML Full-text
Abstract
Fibrinogen can transform fibrin through an agglutination reaction, finally forming fibrin polymer with grid structure. The density and viscosity of the reaction system changes drastically during the course of agglutination. In this research, we apply an independently-developed piezoelectric agglutination sensor to detect the
[...] Read more.
Fibrinogen can transform fibrin through an agglutination reaction, finally forming fibrin polymer with grid structure. The density and viscosity of the reaction system changes drastically during the course of agglutination. In this research, we apply an independently-developed piezoelectric agglutination sensor to detect the fibrinogen agglutination reaction in patients with coronary heart diseases. The terminal judgment method of determining plasma agglutination reaction through piezoelectric agglutination sensor was established. In addition, the standard curve between plasma agglutination time and fibrinogen concentration was established to determinate fibrinogen content quantitatively. The results indicate the close correlation between the STAGO paramagnetic particle method and the method of piezoelectric agglutination sensor for the detection of Fibrinogen. The correlation coefficient was 0.91 (γ = 0.91). The determination can be completed within 10 minutes. The fibrinogen concentration in the coronary heart disease group was significantly higher than that of the healthy control group (P < 0.05). The results reveal that high fibrinogen concentration is closely correlated to the incurrence, development and prognosis of coronary heart diseases. Compared with other traditional methods, the method of piezoelectric agglutination sensor has some merits such as operation convenience, small size, low cost, quick detecting, good precision and the common reacting agents with paramagnetic particle method. Full article
(This article belongs to the Section Biosensors)
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Open AccessReview Metal Oxide Gas Sensors: Sensitivity and Influencing Factors
Sensors 2010, 10(3), 2088-2106; https://doi.org/10.3390/s100302088
Received: 17 February 2010 / Revised: 10 March 2010 / Accepted: 14 March 2010 / Published: 15 March 2010
Cited by 872 | Viewed by 23876 | PDF Full-text (606 KB) | HTML Full-text | XML Full-text
Abstract
Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of
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Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessArticle Coverage-Guaranteed Sensor Node Deployment Strategies for Wireless Sensor Networks
Sensors 2010, 10(3), 2064-2087; https://doi.org/10.3390/s100302064
Received: 30 December 2009 / Revised: 30 January 2010 / Accepted: 3 February 2010 / Published: 15 March 2010
Cited by 45 | Viewed by 6397 | PDF Full-text (513 KB) | HTML Full-text | XML Full-text
Abstract
Deployment quality and cost are two conflicting aspects in wireless sensor networks. Random deployment, where the monitored field is covered by randomly and uniformly deployed sensor nodes, is an appropriate approach for large-scale network applications. However, their successful applications depend considerably on the
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Deployment quality and cost are two conflicting aspects in wireless sensor networks. Random deployment, where the monitored field is covered by randomly and uniformly deployed sensor nodes, is an appropriate approach for large-scale network applications. However, their successful applications depend considerably on the deployment quality that uses the minimum number of sensors to achieve a desired coverage. Currently, the number of sensors required to meet the desired coverage is based on asymptotic analysis, which cannot meet deployment quality due to coverage overestimation in real applications. In this paper, we first investigate the coverage overestimation and address the challenge of designing coverage-guaranteed deployment strategies. To overcome this problem, we propose two deployment strategies, namely, the Expected-area Coverage Deployment (ECD) and BOundary Assistant Deployment (BOAD). The deployment quality of the two strategies is analyzed mathematically. Under the analysis, a lower bound on the number of deployed sensor nodes is given to satisfy the desired deployment quality. We justify the correctness of our analysis through rigorous proof, and validate the effectiveness of the two strategies through extensive simulation experiments. The simulation results show that both strategies alleviate the coverage overestimation significantly. In addition, we also evaluate two proposed strategies in the context of target detection application. The comparison results demonstrate that if the target appears at the boundary of monitored region in a given random deployment, the average intrusion distance of BOAD is considerably shorter than that of ECD with the same desired deployment quality. In contrast, ECD has better performance in terms of the average intrusion distance when the invasion of intruder is from the inside of monitored region. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Response Ant Colony Optimization of End Milling Surface Roughness
Sensors 2010, 10(3), 2054-2063; https://doi.org/10.3390/s100302054
Received: 24 January 2009 / Revised: 8 March 2010 / Accepted: 14 March 2010 / Published: 15 March 2010
Cited by 14 | Viewed by 6196 | PDF Full-text (366 KB) | HTML Full-text | XML Full-text
Abstract
Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents
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Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6) with Response Ant Colony Optimization (RACO). The approach is based on Response Surface Method (RSM) and Ant Colony Optimization (ACO). The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth). The first order model indicates that the feedrate is the most significant factor affecting surface roughness. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Automatic Chessboard Detection for Intrinsic and Extrinsic Camera Parameter Calibration
Sensors 2010, 10(3), 2027-2044; https://doi.org/10.3390/s100302027
Received: 6 January 2010 / Revised: 29 January 2010 / Accepted: 2 February 2010 / Published: 15 March 2010
Cited by 77 | Viewed by 11416 | PDF Full-text (2539 KB) | HTML Full-text | XML Full-text
Abstract
There are increasing applications that require precise calibration of cameras to perform accurate measurements on objects located within images, and an automatic algorithm would reduce this time consuming calibration procedure. The method proposed in this article uses a pattern similar to that of
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There are increasing applications that require precise calibration of cameras to perform accurate measurements on objects located within images, and an automatic algorithm would reduce this time consuming calibration procedure. The method proposed in this article uses a pattern similar to that of a chess board, which is found automatically in each image, when no information regarding the number of rows or columns is supplied to aid its detection. This is carried out by means of a combined analysis of two Hough transforms, image corners and invariant properties of the perspective transformation. Comparative analysis with more commonly used algorithms demonstrate the viability of the algorithm proposed, as a valuable tool for camera calibration. Full article
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Open AccessArticle Signal Amplification by Enzymatic Reaction in an Immunosensor Based on Localized Surface Plasmon Resonance (LSPR)
Sensors 2010, 10(3), 2045-2053; https://doi.org/10.3390/s100302045
Received: 20 January 2010 / Revised: 15 February 2010 / Accepted: 4 March 2010 / Published: 12 March 2010
Cited by 22 | Viewed by 6665 | PDF Full-text (618 KB) | HTML Full-text | XML Full-text
Abstract
An enzymatic reaction was employed as a means to enhance the sensitivity of an immunosensor based on localized surface plasmon resonance (LSPR). The reaction occurs after intermolecular binding between an antigen and an antibody on gold nano-island (NI) surfaces. For LSPR sensing, the
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An enzymatic reaction was employed as a means to enhance the sensitivity of an immunosensor based on localized surface plasmon resonance (LSPR). The reaction occurs after intermolecular binding between an antigen and an antibody on gold nano-island (NI) surfaces. For LSPR sensing, the gold NI surface was fabricated on glass substrates using vacuum evaporation and heat treatment. The interferon-g (IFN-g) capture antibody was immobilized on the gold NIs, followed by binding of IFN-g to the antibody. Subsequently, a biotinylated antibody and a horseradish peroxidase (HRP) conjugated with avidin were simultaneously introduced. A solution of 4-chloro-1-naphthol (4-CN) was then used for precipitation; precipitation was the result of the enzymatic reaction catalyzed the HRP on gold NIs. The LSPR spectra were obtained after each binding process. Using this method, the enzyme-catalyzed precipitation reaction on the gold NI surface was found to effectively amplify the change in the signal of the LSPR immunosensor after intermolecular binding. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle Distributed Power Allocation for Sink-Centric Clusters in Multiple Sink Wireless Sensor Networks
Sensors 2010, 10(3), 2003-2026; https://doi.org/10.3390/s100302003
Received: 6 January 2010 / Revised: 21 January 2010 / Accepted: 7 February 2010 / Published: 11 March 2010
Cited by 6 | Viewed by 9380 | PDF Full-text (420 KB) | HTML Full-text | XML Full-text
Abstract
Due to the battery resource constraints, saving energy is a critical issue in wireless sensor networks, particularly in large sensor networks. One possible solution is to deploy multiple sink nodes simultaneously. Another possible solution is to employ an adaptive clustering hierarchy routing scheme.
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Due to the battery resource constraints, saving energy is a critical issue in wireless sensor networks, particularly in large sensor networks. One possible solution is to deploy multiple sink nodes simultaneously. Another possible solution is to employ an adaptive clustering hierarchy routing scheme. In this paper, we propose a multiple sink cluster wireless sensor networks scheme which combines the two solutions, and propose an efficient transmission power control scheme for a sink-centric cluster routing protocol in multiple sink wireless sensor networks, denoted as MSCWSNs-PC. It is a distributed, scalable, self-organizing, adaptive system, and the sensor nodes do not require knowledge of the global network and their location. All sinks effectively work out a representative view of a monitored region, after which power control is employed to optimize network topology. The simulations demonstrate the advantages of our new protocol. Full article
Open AccessArticle Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination
Sensors 2010, 10(3), 1986-2002; https://doi.org/10.3390/s100301986
Received: 1 February 2010 / Revised: 12 February 2010 / Accepted: 28 February 2010 / Published: 11 March 2010
Cited by 50 | Viewed by 8941 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
We report on the development of a microelectromechanical systems (MEMS)-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL) was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable
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We report on the development of a microelectromechanical systems (MEMS)-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL) was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS) regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle A Comparison of Spectral Angle Mapper and Artificial Neural Network Classifiers Combined with Landsat TM Imagery Analysis for Obtaining Burnt Area Mapping
Sensors 2010, 10(3), 1967-1985; https://doi.org/10.3390/s100301967
Received: 18 December 2009 / Revised: 20 January 2010 / Accepted: 4 February 2010 / Published: 11 March 2010
Cited by 56 | Viewed by 7797 | PDF Full-text (792 KB) | HTML Full-text | XML Full-text
Abstract
Satellite remote sensing, with its unique synoptic coverage capabilities, can provide accurate and immediately valuable information on fire analysis and post-fire assessment, including estimation of burnt areas. In this study the potential for burnt area mapping of the combined use of Artificial Neural
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Satellite remote sensing, with its unique synoptic coverage capabilities, can provide accurate and immediately valuable information on fire analysis and post-fire assessment, including estimation of burnt areas. In this study the potential for burnt area mapping of the combined use of Artificial Neural Network (ANN) and Spectral Angle Mapper (SAM) classifiers with Landsat TM satellite imagery was evaluated in a Mediterranean setting. As a case study one of the most catastrophic forest fires, which occurred near the capital of Greece during the summer of 2007, was used. The accuracy of the two algorithms in delineating the burnt area from the Landsat TM imagery, acquired shortly after the fire suppression, was determined by the classification accuracy results of the produced thematic maps. In addition, the derived burnt area estimates from the two classifiers were compared with independent estimates available for the study region, obtained from the analysis of higher spatial resolution satellite data. In terms of the overall classification accuracy, ANN outperformed (overall accuracy 90.29%, Kappa coefficient 0.878) the SAM classifier (overall accuracy 83.82%, Kappa coefficient 0.795). Total burnt area estimates from the two classifiers were found also to be in close agreement with the other available estimates for the study region, with a mean absolute percentage difference of ~1% for ANN and ~6.5% for SAM. The study demonstrates the potential of the examined here algorithms in detecting burnt areas in a typical Mediterranean setting. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle A Star Recognition Method Based on the Adaptive Ant Colony Algorithm for Star Sensors
Sensors 2010, 10(3), 1955-1966; https://doi.org/10.3390/s100301955
Received: 23 December 2009 / Revised: 13 January 2010 / Accepted: 23 February 2010 / Published: 10 March 2010
Cited by 13 | Viewed by 5568 | PDF Full-text (347 KB) | HTML Full-text | XML Full-text
Abstract
A new star recognition method based on the Adaptive Ant Colony (AAC) algorithm has been developed to increase the star recognition speed and success rate for star sensors. This method draws circles, with the center of each one being a bright star point
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A new star recognition method based on the Adaptive Ant Colony (AAC) algorithm has been developed to increase the star recognition speed and success rate for star sensors. This method draws circles, with the center of each one being a bright star point and the radius being a special angular distance, and uses the parallel processing ability of the AAC algorithm to calculate the angular distance of any pair of star points in the circle. The angular distance of two star points in the circle is solved as the path of the AAC algorithm, and the path optimization feature of the AAC is employed to search for the optimal (shortest) path in the circle. This optimal path is used to recognize the stellar map and enhance the recognition success rate and speed. The experimental results show that when the position error is about 50″, the identification success rate of this method is 98% while the Delaunay identification method is only 94%. The identification time of this method is up to 50 ms. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Advances in Lead-Free Piezoelectric Materials for Sensors and Actuators
Sensors 2010, 10(3), 1935-1954; https://doi.org/10.3390/s100301935
Received: 6 January 2010 / Revised: 3 February 2010 / Accepted: 12 February 2010 / Published: 10 March 2010
Cited by 176 | Viewed by 11827 | PDF Full-text (759 KB) | HTML Full-text | XML Full-text
Abstract
Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1-x] O3 (PZT),are comprised of more than 60 weight percent lead (Pb). Dueto its harmful effects, there is
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Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1-x] O3 (PZT),are comprised of more than 60 weight percent lead (Pb). Dueto its harmful effects, there is a strong impetus to identify new lead-free replacement materials with comparable properties to those of PZT. This review highlights recent developments in several lead-free piezoelectric materials including BaTiO3, Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Na0.5K0.5NbO3, and their solid solutions. The factors that contribute to strong piezoelectric behavior are described and a summary of the properties for the various systems is provided. Full article
(This article belongs to the Special Issue Advances in Actuators)
Open AccessArticle Position Error Compensation via a Variable Reluctance Sensor Applied to a Hybrid Vehicle Electric Machine
Sensors 2010, 10(3), 1918-1934; https://doi.org/10.3390/s100301918
Received: 10 December 2009 / Revised: 8 February 2010 / Accepted: 20 February 2010 / Published: 9 March 2010
Cited by 5 | Viewed by 6445 | PDF Full-text (207 KB) | HTML Full-text | XML Full-text
Abstract
In the automotive industry, electromagnetic variable reluctance (VR) sensors have been extensively used to measure engine position and speed through a toothed wheel mounted on the crankshaft. In this work, an application that already uses the VR sensing unit for engine and/or transmission
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In the automotive industry, electromagnetic variable reluctance (VR) sensors have been extensively used to measure engine position and speed through a toothed wheel mounted on the crankshaft. In this work, an application that already uses the VR sensing unit for engine and/or transmission has been chosen to infer, this time, the indirect position of the electric machine in a parallel Hybrid Electric Vehicle (HEV) system. A VR sensor has been chosen to correct the position of the electric machine, mainly because it may still become critical in the operation of HEVs to avoid possible vehicle failures during the start-up and on-the-road, especially when the machine is used with an internal combustion engine. The proposed method uses Chi-square test and is adaptive in a sense that it derives the compensation factors during the shaft operation and updates them in a timely fashion. Full article
(This article belongs to the Section Chemical Sensors)
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