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Sensors, Volume 7, Issue 5 (May 2007), Pages 628-796

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Editorial

Jump to: Research

Open AccessEditorial Sensors Makes Sense
Sensors 2007, 7(5), 649; doi:10.3390/s7050649
Received: 10 May 2007 / Published: 11 May 2007
PDF Full-text (72 KB) | HTML Full-text | XML Full-text

Research

Jump to: Editorial

Open AccessArticle Distributed Particle Swarm Optimization and Simulated Annealing for Energy-efficient Coverage in Wireless Sensor Networks
Sensors 2007, 7(5), 628-648; doi:10.3390/s7050628
Received: 25 April 2007 / Accepted: 8 May 2007 / Published: 10 May 2007
Cited by 32 | PDF Full-text (403 KB) | HTML Full-text | XML Full-text
Abstract
The limited energy supply of wireless sensor networks poses a great challenge for the deployment of wireless sensor nodes. In this paper, we focus on energy-efficient coverage with distributed particle swarm optimization and simulated annealing. First, the energy-efficient coverage problem is formulated with
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The limited energy supply of wireless sensor networks poses a great challenge for the deployment of wireless sensor nodes. In this paper, we focus on energy-efficient coverage with distributed particle swarm optimization and simulated annealing. First, the energy-efficient coverage problem is formulated with sensing coverage and energy consumption models. We consider the network composed of stationary and mobile nodes. Second, coverage and energy metrics are presented to evaluate the coverage rate and energy consumption of a wireless sensor network, where a grid exclusion algorithm extracts the coverage state and Dijkstra’s algorithm calculates the lowest cost path for communication. Then, a hybrid algorithm optimizes the energy consumption, in which particle swarm optimization and simulated annealing are combined to find the optimal deployment solution in a distributed manner. Simulated annealing is performed on multiple wireless sensor nodes, results of which are employed to correct the local and global best solution of particle swarm optimization. Simulations of wireless sensor node deployment verify that coverage performance can be guaranteed, energy consumption of communication is conserved after deployment optimization and the optimization performance is boosted by the distributed algorithm. Moreover, it is demonstrated that energy efficiency of wireless sensor networks is enhanced by the proposed optimization algorithm in target tracking applications. Full article
Open AccessArticle Improvement of Flame-made ZnO Nanoparticulate Thick Film Morphology for Ethanol Sensing
Sensors 2007, 7(5), 650-675; doi:10.3390/s7050650
Received: 19 April 2007 / Accepted: 11 May 2007 / Published: 15 May 2007
Cited by 24 | PDF Full-text (663 KB) | HTML Full-text | XML Full-text
Abstract
ZnO nanoparticles were produced by flame spray pyrolysis using zinc naphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%). The particles properties were analyzed by XRD, BET. The ZnO particle size and morphology was observed by SEM and HR-TEM revealing spheroidal, hexagonal, and
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ZnO nanoparticles were produced by flame spray pyrolysis using zinc naphthenate as a precursor dissolved in toluene/acetonitrile (80/20 vol%). The particles properties were analyzed by XRD, BET. The ZnO particle size and morphology was observed by SEM and HR-TEM revealing spheroidal, hexagonal, and rod-like morphologies. The crystallite sizes of ZnO spheroidal and hexagonal particles ranged from 10-20 nm. ZnO nanorods were ranged from 10-20 nm in width and 20-50 nm in length. Sensing films were produced by mixing the nanoparticles into an organic paste composed of terpineol and ethyl cellulose as a vehicle binder. The paste was doctor-bladed onto Al2O3 substrates interdigitated with Au electrodes. The morphology of the sensing films was analyzed by optical microscopy and SEM analysis. Cracking of the sensing films during annealing process was improved by varying the heating conditions. The gas sensing of ethanol (25-250 ppm) was studied at 400 °C in dry air containing SiC as the fluidized particles. The oxidation of ethanol on the surface of the semiconductor was confirmed by mass spectroscopy (MS). The effect of micro-cracks was quantitatively accounted for as a provider of extra exposed edges. The sensitivity decreased notably with increasing crack of sensing films. It can be observed that crack widths were reduced with decreasing heating rates. Crack-free of thick (5 μm) ZnO films evidently showed higher sensor signal and faster response times (within seconds) than cracked sensor. The sensor signal increased and the response time decreased with increasing ethanol concentration. Full article
Open AccessArticle Behavior of Random Hole Optical Fibers under Gamma Ray Irradiation and Its Potential Use in Radiation Sensing Applications
Sensors 2007, 7(5), 676-688; doi:10.3390/s7050676
Received: 29 March 2007 / Accepted: 22 May 2007 / Published: 24 May 2007
Cited by 8 | PDF Full-text (1688 KB) | HTML Full-text | XML Full-text
Abstract
Effects of radiation on sensing and data transmission components are of greatinterest in many applications including homeland security, nuclear power generation, andmilitary. A new type of microstructured optical fiber (MOF) called the random hole opticalfiber (RHOF) has been recently developed. The RHOFs can
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Effects of radiation on sensing and data transmission components are of greatinterest in many applications including homeland security, nuclear power generation, andmilitary. A new type of microstructured optical fiber (MOF) called the random hole opticalfiber (RHOF) has been recently developed. The RHOFs can be made in many differentforms by varying the core size and the size and extent of porosity in the cladding region.The fibers used in this study possessed an outer diameter of 110 μm and a core ofapproximately 20 μm. The fiber structure contains thousands of air holes surrounding thecore with sizes ranging from less than 100 nm to a few μm. We present the first study ofthe behavior of RHOF under gamma irradiation. We also propose, for the first time to ourknowledge, an ionizing radiation sensor system based on scintillation light from ascintillator phosphor embedded within a holey optical fiber structure. The RHOF radiationresponse was compared to normal single mode and multimode commercial fibers(germanium doped core, pure silica cladding) and to those of radiation resistant fibers (puresilica core with fluorine doped cladding fibers). The comparison was done by measuringradiation-induced absorption (RIA) in all fiber samples at the 1550 nm wavelength window(1545 ± 25 nm). The study was carried out under a high-intensity gamma ray field from a 60Co source (with an exposure rate of 4x104 rad/hr) at an Oak Ridge National Laboratory gamma ray irradiation facility. Linear behavior, at dose values less than 106 rad, was observed in all fiber samples except in the pure silica core fluorine doped cladding fiber which showed RIA saturation at 0.01 dB. RHOF samples demonstrated low RIA (0.02 and 0.005 dB) compared to standard germanium doped core pure silica cladding (SMF and MMF) fibers. Results also showed the possibility of post-fabrication treatment to improve the radiation resistance of the RHOF fibers. Full article
Open AccessArticle Simulation of Optical Microfiber Loop Resonators for Ambient Refractive Index Sensing
Sensors 2007, 7(5), 689-696; doi:10.3390/s7050689
Received: 4 April 2007 / Accepted: 3 May 2007 / Published: 24 May 2007
Cited by 28 | PDF Full-text (195 KB) | HTML Full-text | XML Full-text
Abstract
Based on theoretical modeling and optimization, we exploit the application ofoptical microfiber loop resonators in ambient refractive index sensing. We set up a reliabletheoretical model and optimize the structural parameters of microfiber loop resonatorsincluding the radius of the microrfiber, the radius of the
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Based on theoretical modeling and optimization, we exploit the application ofoptical microfiber loop resonators in ambient refractive index sensing. We set up a reliabletheoretical model and optimize the structural parameters of microfiber loop resonatorsincluding the radius of the microrfiber, the radius of the loop and the length of the couplingregion for higher sensitivity, wider dynamic measurement range, and lower detection limit.To show the convincible and realizable sensing ability we perform the simulation ofsensing an extreme small variation of ambient refractive index by employing a set ofexperimental data as the parameters in the expression of intensity transmission coefficient,and the detection limit reaches to a variation of ambient refractive index of 10-5 refractiveindex unit (RIU). This has superiority over the existing evanescent field-basedsubwavelength-diameter optical fiber refractive index sensor. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle An Experimental Study on the Fabrication of Glass-based Acceleration Sensor Body Using Micro Powder Blasting Method
Sensors 2007, 7(5), 697-707; doi:10.3390/s7050697
Received: 2 May 2007 / Accepted: 21 May 2007 / Published: 24 May 2007
Cited by 5 | PDF Full-text (774 KB) | HTML Full-text | XML Full-text
Abstract
This study investigated the feasibility of the micro powder blasting technique for the micro fabrication of sensor structures using the Pyrex glass to replace the existing silicon-based acceleration sensor fabrication processes. As the preliminary experiments, the effects of the blasting pressure, the mass
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This study investigated the feasibility of the micro powder blasting technique for the micro fabrication of sensor structures using the Pyrex glass to replace the existing silicon-based acceleration sensor fabrication processes. As the preliminary experiments, the effects of the blasting pressure, the mass flow rate of abrasive and the number of nozzle scanning times on erosion depth of the Pyrex and the soda lime glasses were examined. From the experimental results, optimal blasting conditions were selected for the Pyrex glass machining. The dimensions of the designed glass sensor was 1.7×1.7×0.6mm for the vibrating mass, and 2.9×0.7×0.2mm for the cantilever beam. The machining results showed that the dimensional errors of the machined glass sensor ranged from 3 μm in minimum to 20 μm in maximum. These results imply that the micro powder blasting method can be applied for the micromachining of glass-based acceleration sensors to replace the exiting method. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)
Open AccessArticle Preparation of Silver Nanoparticle and Its Application to the Determination of ct-DNA
Sensors 2007, 7(5), 708-718; doi:10.3390/s7050708
Received: 16 March 2007 / Accepted: 29 May 2007 / Published: 31 May 2007
Cited by 42 | PDF Full-text (881 KB) | HTML Full-text | XML Full-text
Abstract
A new method to prepare silver nanoparticles was reported in this paper, whichbased on aqueous-gaseous phase reaction of silver nitrate solution and ammonia gas. Theproposed method is effective, rapid, and convenient. Transmission electron microscope(TEM) and X-ray diffraction (XRD) were used to characterize the
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A new method to prepare silver nanoparticles was reported in this paper, whichbased on aqueous-gaseous phase reaction of silver nitrate solution and ammonia gas. Theproposed method is effective, rapid, and convenient. Transmission electron microscope(TEM) and X-ray diffraction (XRD) were used to characterize the structure of the particles,respectively. It was found that the average diameter of the particles was about 10 nm and theshape was spherical. And the strong fluorescence signal of the silver nanoparticles solutioncan be quenched after the adding of the calf thymus DNA (ct-DNA) solution. Thequenched fluorescence intensity was linear with the concentration of ct-DNA in the range of0.5 to 5.0 × 104 ng mL-1 with a detection limit of 0.3 ng mL-1. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Horseradish Peroxidase (HRP) Immobilized Poly(aniline-co-m-aminophenol) Film Electrodes–fabrication and Evaluation as Hydrogen Peroxide Sensor
Sensors 2007, 7(5), 719-729; doi:10.3390/s7050719
Received: 17 April 2007 / Accepted: 29 May 2007 / Published: 31 May 2007
Cited by 18 | PDF Full-text (3862 KB) | HTML Full-text | XML Full-text
Abstract
Enzyme modified electrodes were fabricated with poly(aniline-co-m-aminophenol). Electrochemical polymerization of aniline and m-aminophenol wasperformed to get the film of copolymer on the surface of gold electrode. Modifiedelectrodes were fabricated by two methods, physical entrapment and covalent cross-linking.In one of the method, gold nanoparticles
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Enzyme modified electrodes were fabricated with poly(aniline-co-m-aminophenol). Electrochemical polymerization of aniline and m-aminophenol wasperformed to get the film of copolymer on the surface of gold electrode. Modifiedelectrodes were fabricated by two methods, physical entrapment and covalent cross-linking.In one of the method, gold nanoparticles were loaded into the copolymer film andhorseradish peroxidase (HRP) was immobilized into the Au nanoparticle loaded copolymerfilm through physical entrapment. In the other method, the amino and -OH groups in thecopolymer are utilized to form covalent functionalization with HRP via glutaric dialdehydeas cross-linker/mediator. The conducting copolymer/enzyme modified electrodes preparedby physical entrapment/covalent functionalization of enzyme were tested forelectrocatalytic activities towards sensing of H2O2. Amperometric results indicate thatenzyme modified electrode via physical entrapment possesses better electrocatalyticperformance over covalent functionalized enzyme electrode. Full article
Open AccessArticle Optimized Self Organized Sensor Networks
Sensors 2007, 7(5), 730-742; doi:10.3390/s7050730
Received: 26 April 2007 / Accepted: 30 May 2007 / Published: 31 May 2007
Cited by 15 | PDF Full-text (308 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks are composed of a huge number of sensor nodes, which have limited resources - energy, memory and computation power. Energies are directly related to the lifetime of sensor network. If sensor nodes can be grouped to clusters, cluster member sensor
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Wireless sensor networks are composed of a huge number of sensor nodes, which have limited resources - energy, memory and computation power. Energies are directly related to the lifetime of sensor network. If sensor nodes can be grouped to clusters, cluster member sensor nodes only need to communicate with cluster center (head) and this leads to energy conservation of the member sensors. So, how to compose clusters with minimal number of cluster heads, while including each node in a cluster is an important research issue. We propose a new advanced optimization algorithm for sensor network clustering. Using the proposed optimization algorithm, redundant cluster heads are eliminated, and unnecessarily overlapped clusters are merged. Optimization algorithm can be used as a clustering algorithm by itself and also manage the dynamic changes like node addition or die-out, while the network is even on the working state. We tested the proposed method as a clustering algorithm and compared it with two other recent sensor network clustering algorithms, Algorithm for Cluster Establishment (ACE) and Self Organizing Sensor network algorithm (SOS). The experiments results not only illustrate that the proposed algorithm could result in clusters with smaller number of cluster heads than others with any density of sensor networks, but also that the performance is more stable, which is also verified through repeated experiments. Full article
Open AccessArticle Multi-instrumental Investigation of Affecting of Early Somatic Embryos of Spruce by Cadmium(II) and Lead(II) Ions
Sensors 2007, 7(5), 743-759; doi:10.3390/s7050743
Received: 5 May 2007 / Accepted: 23 May 2007 / Published: 31 May 2007
Cited by 50 | PDF Full-text (537 KB) | HTML Full-text | XML Full-text
Abstract
The main aim of this work was to use multi-instrumental analytical apparatus toinvestigate the effects of treatment with cadmium(II) and/or lead(II) ions (50, 250 and 500μM) for twelve days on early somatic spruce embryos (ESEs). Primarily we used imageanalysis for estimation of growth
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The main aim of this work was to use multi-instrumental analytical apparatus toinvestigate the effects of treatment with cadmium(II) and/or lead(II) ions (50, 250 and 500μM) for twelve days on early somatic spruce embryos (ESEs). Primarily we used imageanalysis for estimation of growth and a fluorimetric sensor for enzymatic detection ofviability of the treated ESEs. It follows from the obtained results that Cd caused highertoxicity to ESEs than Pb. Besides this fundamental finding, we observed that ESEs grewand developed better in the presence of 500 μM of the metal ions than in the presence of250 μM. Based on the results obtained using nuclear magnetic resonance this phenomenonwas related to an increase of the area of ESE clusters by intensive uptake of water from thecultivation medium, due to dilution of the heavy metal concentration inside the cluster. Inaddition we studied the glutathione content in treated ESEs by the adsorptive transferstripping technique coupled with the differential pulse voltammetry Brdicka reaction. GSHcontents increased up to 148 ng/mg (clone 2/32) and 158 ng/mg (clone PE 14) after twelve day long treatment with Cd-EDTA ions. The GSH content was about 150 and 160 % higher in comparison with the ESEs treated with Pb-EDTA ions, respectively. The difference between GSH contents determined in ESEs treated with Pb-EDTA and Cd-EDTA ions correlates with the higher toxicity of cadmium(II) ions. Full article
Open AccessArticle Stability, Nonlinearity and Reliability of Electrostatically Actuated MEMS Devices
Sensors 2007, 7(5), 760-796; doi:10.3390/s7050760
Received: 13 April 2007 / Accepted: 21 May 2007 / Published: 31 May 2007
Cited by 43 | PDF Full-text (605 KB) | HTML Full-text | XML Full-text
Abstract
Electrostatic micro-electro-mechanical system (MEMS) is a special branch with a wide range of applications in sensing and actuating devices in MEMS. This paper provides a survey and analysis of the electrostatic force of importance in MEMS, its physical model, scaling effect, stability, nonlinearity
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Electrostatic micro-electro-mechanical system (MEMS) is a special branch with a wide range of applications in sensing and actuating devices in MEMS. This paper provides a survey and analysis of the electrostatic force of importance in MEMS, its physical model, scaling effect, stability, nonlinearity and reliability in detail. It is necessary to understand the effects of electrostatic forces in MEMS and then many phenomena of practical importance, such as pull-in instability and the effects of effective stiffness, dielectric charging, stress gradient, temperature on the pull-in voltage, nonlinear dynamic effects and reliability due to electrostatic forces occurred in MEMS can be explained scientifically, and consequently the great potential of MEMS technology could be explored effectively and utilized optimally. A simplified parallel-plate capacitor model is proposed to investigate the resonance response, inherent nonlinearity, stiffness softened effect and coupled nonlinear effect of the typical electrostatically actuated MEMS devices. Many failure modes and mechanisms and various methods and techniques, including materials selection, reasonable design and extending the controllable travel range used to analyze and reduce the failures are discussed in the electrostatically actuated MEMS devices. Numerical simulations and discussions indicate that the effects of instability, nonlinear characteristics and reliability subjected to electrostatic forces cannot be ignored and are in need of further investigation. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

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