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Sensors, Volume 9, Issue 8 (August 2009), Pages 5878-6603

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Open AccessArticle Performance of a Protected Wireless Sensor Network in a Fire. Analysis of Fire Spread and Data Transmission
Sensors 2009, 9(8), 5878-5893; doi:10.3390/s90805878
Received: 3 July 2009 / Revised: 20 July 2009 / Accepted: 22 July 2009 / Published: 24 July 2009
Cited by 32 | PDF Full-text (435 KB) | HTML Full-text | XML Full-text
Abstract
The paper deals with a Wireless Sensor Network (WSN) as a reliable solution for capturing the kinematics of a fire front spreading over a fuel bed. To provide reliable information in fire studies and support fire fighting strategies, a Wireless Sensor Network [...] Read more.
The paper deals with a Wireless Sensor Network (WSN) as a reliable solution for capturing the kinematics of a fire front spreading over a fuel bed. To provide reliable information in fire studies and support fire fighting strategies, a Wireless Sensor Network must be able to perform three sequential actions: 1) sensing thermal data in the open as the gas temperature; 2) detecting a fire i.e., the spatial position of a flame; 3) tracking the fire spread during its spatial and temporal evolution. One of the great challenges in performing fire front tracking with a WSN is to avoid the destruction of motes by the fire. This paper therefore shows the performance of Wireless Sensor Network when the motes are protected with a thermal insulation dedicated to track a fire spreading across vegetative fuels on a field scale. The resulting experimental WSN is then used in series of wildfire experiments performed in the open in vegetation areas ranging in size from 50 to 1,000 m². Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Curvature-Based Environment Description for Robot Navigation Using Laser Range Sensors
Sensors 2009, 9(8), 5894-5918; doi:10.3390/s90805894
Received: 15 May 2009 / Revised: 22 June 2009 / Accepted: 24 June 2009 / Published: 24 July 2009
Cited by 22 | PDF Full-text (2646 KB) | HTML Full-text | XML Full-text
Abstract
This work proposes a new feature detection and description approach for mobile robot navigation using 2D laser range sensors. The whole process consists of two main modules: a sensor data segmentation module and a feature detection and characterization module. The segmentation module [...] Read more.
This work proposes a new feature detection and description approach for mobile robot navigation using 2D laser range sensors. The whole process consists of two main modules: a sensor data segmentation module and a feature detection and characterization module. The segmentation module is divided in two consecutive stages: First, the segmentation stage divides the laser scan into clusters of consecutive range readings using a distance-based criterion. Then, the second stage estimates the curvature function associated to each cluster and uses it to split it into a set of straight-line and curve segments. The curvature is calculated using a triangle-area representation where, contrary to previous approaches, the triangle side lengths at each range reading are adapted to the local variations of the laser scan, removing noise without missing relevant points. This representation remains unchanged in translation or rotation, and it is also robust against noise. Thus, it is able to provide the same segmentation results although the scene will be perceived from different viewpoints. Therefore, segmentation results are used to characterize the environment using line and curve segments, real and virtual corners and edges. Real scan data collected from different environments by using different platforms are used in the experiments in order to evaluate the proposed environment description algorithm. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle Inertial and Magnetic Sensor Data Compression Considering the Estimation Error
Sensors 2009, 9(8), 5919-5932; doi:10.3390/s90805919
Received: 22 June 2009 / Revised: 15 July 2009 / Accepted: 17 July 2009 / Published: 24 July 2009
Cited by 1 | PDF Full-text (245 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a compression method for inertial and magnetic sensor data, where the compressed data are used to estimate some states. When sensor data are bounded, the proposed compression method guarantees that the compression error is smaller than a prescribed bound. [...] Read more.
This paper presents a compression method for inertial and magnetic sensor data, where the compressed data are used to estimate some states. When sensor data are bounded, the proposed compression method guarantees that the compression error is smaller than a prescribed bound. The manner in which this error bound affects the bit rate and the estimation error is investigated. Through the simulation, it is shown that the estimation error is improved by 18.81% over a test set of 12 cases compared with a filter that does not use the compression error bound. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle A 1,000 Frames/s Programmable Vision Chip with Variable Resolution and Row-Pixel-Mixed Parallel Image Processors
Sensors 2009, 9(8), 5933-5951; doi:10.3390/s90805933
Received: 11 May 2009 / Revised: 24 July 2009 / Accepted: 24 July 2009 / Published: 27 July 2009
Cited by 11 | PDF Full-text (796 KB) | HTML Full-text | XML Full-text
Abstract
A programmable vision chip with variable resolution and row-pixel-mixed parallel image processors is presented. The chip consists of a CMOS sensor array, with row-parallel 6-bit Algorithmic ADCs, row-parallel gray-scale image processors, pixel-parallel SIMD Processing Element (PE) array, and instruction controller. The resolution [...] Read more.
A programmable vision chip with variable resolution and row-pixel-mixed parallel image processors is presented. The chip consists of a CMOS sensor array, with row-parallel 6-bit Algorithmic ADCs, row-parallel gray-scale image processors, pixel-parallel SIMD Processing Element (PE) array, and instruction controller. The resolution of the image in the chip is variable: high resolution for a focused area and low resolution for general view. It implements gray-scale and binary mathematical morphology algorithms in series to carry out low-level and mid-level image processing and sends out features of the image for various applications. It can perform image processing at over 1,000 frames/s (fps). A prototype chip with 64 × 64 pixels resolution and 6-bit gray-scale image is fabricated in 0.18 mm Standard CMOS process. The area size of chip is 1.5 mm × 3.5 mm. Each pixel size is 9.5 μm × 9.5 μm and each processing element size is 23 μm × 29 μm. The experiment results demonstrate that the chip can perform low-level and mid-level image processing and it can be applied in the real-time vision applications, such as high speed target tracking. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Oscillation Control Algorithms for Resonant Sensors with Applications to Vibratory Gyroscopes
Sensors 2009, 9(8), 5952-5967; doi:10.3390/s90805952
Received: 30 June 2009 / Revised: 22 July 2009 / Accepted: 27 July 2009 / Published: 27 July 2009
Cited by 14 | PDF Full-text (343 KB) | HTML Full-text | XML Full-text
Abstract
We present two oscillation control algorithms for resonant sensors such as vibratory gyroscopes. One control algorithm tracks the resonant frequency of the resonator and the other algorithm tunes it to the specified resonant frequency by altering the resonator dynamics. Both algorithms maintain [...] Read more.
We present two oscillation control algorithms for resonant sensors such as vibratory gyroscopes. One control algorithm tracks the resonant frequency of the resonator and the other algorithm tunes it to the specified resonant frequency by altering the resonator dynamics. Both algorithms maintain the specified amplitude of oscillations. The stability of each of the control systems is analyzed using the averaging method, and quantitative guidelines are given for selecting the control gains needed to achieve stability. The effects of displacement measurement noise on the accuracy of tracking and estimation of the resonant frequency are also analyzed. The proposed control algorithms are applied to two important problems in a vibratory gyroscope. The first is the leading-following resonator problem in the drive axis of MEMS dual-mass vibratory gyroscope where there is no mechanical linkage between the two proof-masses and the second is the on-line modal frequency matching problem in a general vibratory gyroscope. Simulation results demonstrate that the proposed control algorithms are effective. They ensure the proof-masses to oscillate in an anti-phase manner with the same resonant frequency and oscillation amplitude in a dual-mass gyroscope, and two modal frequencies to match in a general vibratory gyroscope. Full article
(This article belongs to the Special Issue Sensor Algorithms)
Open AccessArticle S3: School Zone Safety System Based on Wireless Sensor Network
Sensors 2009, 9(8), 5968-5988; doi:10.3390/s90805968
Received: 21 May 2009 / Revised: 13 July 2009 / Accepted: 28 July 2009 / Published: 28 July 2009
Cited by 10 | PDF Full-text (770 KB) | HTML Full-text | XML Full-text
Abstract
School zones are areas near schools that have lower speed limits and where illegally parked vehicles pose a threat to school children by obstructing them from the view of drivers. However, these laws are regularly flouted. Thus, we propose a novel wireless [...] Read more.
School zones are areas near schools that have lower speed limits and where illegally parked vehicles pose a threat to school children by obstructing them from the view of drivers. However, these laws are regularly flouted. Thus, we propose a novel wireless sensor network application called School zone Safety System (S3) to help regulate the speed limit and to prevent illegal parking in school zones. S3 detects illegally parked vehicles, and warns the driver and records the license plate number. To reduce the traveling speed of vehicles in a school zone, S3 measures the speed of vehicles and displays the speed to the driver via an LED display, and also captures the image of the speeding vehicle with a speed camera. We developed a state machine based vehicle detection algorithm for S3. From extensive experiments in our testbeds and data from a real school zone, it is shown that the system can detect all kinds of vehicles, and has an accuracy of over 95% for speed measurement. We modeled the battery life time of a sensor node and validated the model with a downscaled measurement; we estimate the battery life time to be over 2 years. We have deployed S3 in 15 school zones in 2007, and we have demonstrated the robustness of S3 by operating them for over 1 year. Full article
(This article belongs to the Special Issue Sensor Algorithms)
Open AccessArticle Intrusion-Aware Alert Validation Algorithm for Cooperative Distributed Intrusion Detection Schemes of Wireless Sensor Networks
Sensors 2009, 9(8), 5989-6007; doi:10.3390/s90805989
Received: 24 April 2009 / Revised: 25 June 2009 / Accepted: 17 July 2009 / Published: 28 July 2009
Cited by 6 | PDF Full-text (543 KB) | HTML Full-text | XML Full-text
Abstract
Existing anomaly and intrusion detection schemes of wireless sensor networks have mainly focused on the detection of intrusions. Once the intrusion is detected, an alerts or claims will be generated. However, any unidentified malicious nodes in the network could send faulty anomaly [...] Read more.
Existing anomaly and intrusion detection schemes of wireless sensor networks have mainly focused on the detection of intrusions. Once the intrusion is detected, an alerts or claims will be generated. However, any unidentified malicious nodes in the network could send faulty anomaly and intrusion claims about the legitimate nodes to the other nodes. Verifying the validity of such claims is a critical and challenging issue that is not considered in the existing cooperative-based distributed anomaly and intrusion detection schemes of wireless sensor networks. In this paper, we propose a validation algorithm that addresses this problem. This algorithm utilizes the concept of intrusion-aware reliability that helps to provide adequate reliability at a modest communication cost. In this paper, we also provide a security resiliency analysis of the proposed intrusion-aware alert validation algorithm. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle Orientation of Airborne Laser Scanning Point Clouds with Multi-View, Multi-Scale Image Blocks
Sensors 2009, 9(8), 6008-6027; doi:10.3390/s90806008
Received: 6 May 2009 / Revised: 19 June 2009 / Accepted: 15 July 2009 / Published: 29 July 2009
Cited by 8 | PDF Full-text (601 KB) | HTML Full-text | XML Full-text
Abstract
Comprehensive 3D modeling of our environment requires integration of terrestrial and airborne data, which is collected, preferably, using laser scanning and photogrammetric methods. However, integration of these multi-source data requires accurate relative orientations. In this article, two methods for solving relative orientation [...] Read more.
Comprehensive 3D modeling of our environment requires integration of terrestrial and airborne data, which is collected, preferably, using laser scanning and photogrammetric methods. However, integration of these multi-source data requires accurate relative orientations. In this article, two methods for solving relative orientation problems are presented. The first method includes registration by minimizing the distances between of an airborne laser point cloud and a 3D model. The 3D model was derived from photogrammetric measurements and terrestrial laser scanning points. The first method was used as a reference and for validation. Having completed registration in the object space, the relative orientation between images and laser point cloud is known. The second method utilizes an interactive orientation method between a multi-scale image block and a laser point cloud. The multi-scale image block includes both aerial and terrestrial images. Experiments with the multi-scale image block revealed that the accuracy of a relative orientation increased when more images were included in the block. The orientations of the first and second methods were compared. The comparison showed that correct rotations were the most difficult to detect accurately by using the interactive method. Because the interactive method forces laser scanning data to fit with the images, inaccurate rotations cause corresponding shifts to image positions. However, in a test case, in which the orientation differences included only shifts, the interactive method could solve the relative orientation of an aerial image and airborne laser scanning data repeatedly within a couple of centimeters. Full article
(This article belongs to the Special Issue LiDAR for 3D City Modeling)
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Open AccessArticle MCBT: Multi-Hop Cluster Based Stable Backbone Trees for Data Collection and Dissemination in WSNs
Sensors 2009, 9(8), 6028-6045; doi:10.3390/s90806028
Received: 26 June 2009 / Revised: 9 July 2009 / Accepted: 17 July 2009 / Published: 29 July 2009
Cited by 18 | PDF Full-text (935 KB) | HTML Full-text | XML Full-text
Abstract
We propose a stable backbone tree construction algorithm using multi-hop clusters for wireless sensor networks (WSNs). The hierarchical cluster structure has advantages in data fusion and aggregation. Energy consumption can be decreased by managing nodes with cluster heads. Backbone nodes, which are [...] Read more.
We propose a stable backbone tree construction algorithm using multi-hop clusters for wireless sensor networks (WSNs). The hierarchical cluster structure has advantages in data fusion and aggregation. Energy consumption can be decreased by managing nodes with cluster heads. Backbone nodes, which are responsible for performing and managing multi-hop communication, can reduce the communication overhead such as control traffic and minimize the number of active nodes. Previous backbone construction algorithms, such as Hierarchical Cluster-based Data Dissemination (HCDD) and Multicluster, Mobile, Multimedia radio network (MMM), consume energy quickly. They are designed without regard to appropriate factors such as residual energy and degree (the number of connections or edges to other nodes) of a node for WSNs. Thus, the network is quickly disconnected or has to reconstruct a backbone. We propose a distributed algorithm to create a stable backbone by selecting the nodes with higher energy or degree as the cluster heads. This increases the overall network lifetime. Moreover, the proposed method balances energy consumption by distributing the traffic load among nodes around the cluster head. In the simulation, the proposed scheme outperforms previous clustering schemes in terms of the average and the standard deviation of residual energy or degree of backbone nodes, the average residual energy of backbone nodes after disseminating the sensed data, and the network lifetime. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle Deflection, Frequency, and Stress Characteristics of Rectangular, Triangular, and Step Profile Microcantilevers for Biosensors
Sensors 2009, 9(8), 6046-6057; doi:10.3390/s90806046
Received: 16 July 2009 / Revised: 27 July 2009 / Accepted: 28 July 2009 / Published: 29 July 2009
Cited by 34 | PDF Full-text (375 KB) | HTML Full-text | XML Full-text
Abstract
This study presents the deflection, resonant frequency and stress results of rectangular, triangular, and step profile microcantilevers subject to surface stress. These cantilevers can be used as the sensing element in microcantilever biosensors. To increase the overall sensitivity of microcantilever biosensors, both [...] Read more.
This study presents the deflection, resonant frequency and stress results of rectangular, triangular, and step profile microcantilevers subject to surface stress. These cantilevers can be used as the sensing element in microcantilever biosensors. To increase the overall sensitivity of microcantilever biosensors, both the deflection and the resonant frequency of the cantilever should be increased. The effect of the cantilever profile change and the cantilever cross-section shape change is first investigated separately and then together. A finite element code ANSYS Multiphysics is used and solid finite elements cantilever models are solved. A surface stress of 0.05 N/m was applied to the top surface of the cantilevers. The cantilevers are made of silicon with elastic modulus 130 GPa and Poisson’s ratio 0.28. To show the conformity of this study, the numerical results are compared against their analytical ones. Results show that triangular and step cantilevers have better deflection and frequency characteristics than rectangular ones. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle From Lateral Flow Devices to a Novel Nano-Color Microfluidic Assay
Sensors 2009, 9(8), 6084-6100; doi:10.3390/s90806084
Received: 15 July 2009 / Revised: 24 July 2009 / Accepted: 29 July 2009 / Published: 31 July 2009
Cited by 14 | PDF Full-text (680 KB) | HTML Full-text | XML Full-text
Abstract
Improving the performance of traditional diagnostic lateral flow assays combined with new manufacturing technologies is a primary goal in the research and development plans of diagnostic companies. Taking into consideration the components of lateral flow diagnostic test kits; innovation can include modification [...] Read more.
Improving the performance of traditional diagnostic lateral flow assays combined with new manufacturing technologies is a primary goal in the research and development plans of diagnostic companies. Taking into consideration the components of lateral flow diagnostic test kits; innovation can include modification of labels, materials and device design. In recent years, Resonance-Enhanced Absorption (REA) of metal nano-particles has shown excellent applicability in bio-sensing for the detection of a variety of bio-molecular binding interactions. In a novel approach, we have now integrated REA-assays in a diagnostic microfluidic setup thus resolving the bottleneck of long incubation times inherent in previously existing REA-assays and simultaneously integrated automated fabrication techniques for diagnostics manufacture. Due to the roller-coating based technology and chemical resistance, we used PET-co-polyester as a substrate and a CO2 laser ablation system as a fast, highly precise and contactless alternative to classical micro-milling. It was possible to detect biological binding within three minutes – visible to the eye as colored text readout within the REA-fluidic device. A two-minute in-situ silver enhancement was able to enhance the resonant color additionally, if required. Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
Open AccessArticle Building Reconstruction by Target Based Graph Matching on Incomplete Laser Data: Analysis and Limitations
Sensors 2009, 9(8), 6101-6118; doi:10.3390/s90806101
Received: 7 May 2009 / Revised: 12 June 2009 / Accepted: 15 July 2009 / Published: 31 July 2009
Cited by 52 | PDF Full-text (2215 KB) | HTML Full-text | XML Full-text
Abstract
With the increasing point densities provided by airborne laser scanner (ALS) data the requirements on derived products also increase. One major application of ALS data is to provide input for 3D city models. Modeling of roof faces, (3D) road and terrain surfaces [...] Read more.
With the increasing point densities provided by airborne laser scanner (ALS) data the requirements on derived products also increase. One major application of ALS data is to provide input for 3D city models. Modeling of roof faces, (3D) road and terrain surfaces can partially be done in an automated manner, although many such approaches are still in a development stage. Problems in automatic building reconstruction lie in the dynamic area between assumptions and reality. Not every object in the data appears as the algorithm expects. Challenges are to detect areas that cannot be reconstructed automatically. This paper describes our contribution to the field of building reconstruction by proposing a target based graph matching approach that can handle both complete and incomplete laser data. Match results describe which target objects appear topologically in the data. Complete match results can be reconstructed in an automated manner. Quality parameters store information on how the model fits to the input data and which data has not been used. Areas where laser data only partly matches with target objects are detected automatically. Four datasets are analyzed in order to describe the quality of the automatically reconstructed roofs, and to point out the reasons why segments are left out from the automatic reconstruction. The reasons why these areas are left out include lack of data information and limitations of our initial target objects. Potential improvement to our approach is to include likelihood functions to the existence of topological relations. Full article
(This article belongs to the Special Issue LiDAR for 3D City Modeling)
Open AccessArticle Distortion of Near-Surface Seawater Temperature Structure by a Moored-Buoy Hull and Its Effect on Skin Temperature and Heat Flux Estimates
Sensors 2009, 9(8), 6119-6130; doi:10.3390/s90806119
Received: 26 June 2009 / Revised: 27 July 2009 / Accepted: 29 July 2009 / Published: 31 July 2009
Cited by 4 | PDF Full-text (607 KB) | HTML Full-text | XML Full-text
Abstract
Previous studies have suggested that the accuracy of temperature measurements by surface-moored buoys may be affected by distortions of the near-surface temperature structure by the buoy hull on calm, sunny days. We obtained the first definite observational evidence that the temperature near [...] Read more.
Previous studies have suggested that the accuracy of temperature measurements by surface-moored buoys may be affected by distortions of the near-surface temperature structure by the buoy hull on calm, sunny days. We obtained the first definite observational evidence that the temperature near the hull was not horizontally homogeneous at the same nominal depth. We observed large temperature differences of 1.0 K or more between thermometers at 0.2 m depth. The distortion of the surface temperature field yielded an error in estimates of daytime net surface heat flux up to more than 30 Wm2. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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Open AccessArticle Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals
Sensors 2009, 9(8), 6131-6149; doi:10.3390/s90806131
Received: 1 July 2009 / Revised: 29 July 2009 / Accepted: 31 July 2009 / Published: 3 August 2009
Cited by 11 | PDF Full-text (671 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring [...] Read more.
The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called “baseline errors” associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN) signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver’s output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network. Full article
Open AccessArticle An Efficient and Self-Adapting Localization in Static Wireless Sensor Networks
Sensors 2009, 9(8), 6150-6170; doi:10.3390/s90806150
Received: 28 May 2009 / Revised: 24 June 2009 / Accepted: 29 July 2009 / Published: 4 August 2009
Cited by 5 | PDF Full-text (991 KB) | HTML Full-text | XML Full-text
Abstract
Localization is one of the most important subjects in Wireless Sensor Networks (WSNs). To reduce the number of beacons and adopt probabilistic methods, some particle filter-based mobile beacon-assisted localization approaches have been proposed, such as Mobile Beacon-assisted Localization (MBL), Adapting MBL (A-MBL), [...] Read more.
Localization is one of the most important subjects in Wireless Sensor Networks (WSNs). To reduce the number of beacons and adopt probabilistic methods, some particle filter-based mobile beacon-assisted localization approaches have been proposed, such as Mobile Beacon-assisted Localization (MBL), Adapting MBL (A-MBL), and the method proposed by Hang et al. Some new significant problems arise in these approaches, however. The first question is which probability distribution should be selected as the dynamic model in the prediction stage. The second is whether the unknown node adopts neighbors’ observation in the update stage. The third is how to find a self-adapting mechanism to achieve more flexibility in the adapting stage. In this paper, we give the theoretical analysis and experimental evaluations to suggest which probability distribution in the dynamic model should be adopted to improve the efficiency in the prediction stage. We also give the condition for whether the unknown node should use the observations from its neighbors to improve the accuracy. Finally, we propose a Self-Adapting Mobile Beacon-assisted Localization (SA-MBL) approach to achieve more flexibility and achieve almost the same performance with A-MBL. Full article
(This article belongs to the Special Issue Sensor Algorithms)
Open AccessArticle Monitoring System for Farming Operations with Wearable Devices Utilized Sensor Networks
Sensors 2009, 9(8), 6171-6184; doi:10.3390/s90806171
Received: 18 June 2009 / Revised: 19 July 2009 / Accepted: 21 July 2009 / Published: 4 August 2009
Cited by 10 | PDF Full-text (1768 KB) | HTML Full-text | XML Full-text
Abstract
In order to automatically monitor farmers’ activities, we propose a farm operation monitoring system using “Field Servers” and a wearable device equipped with an RFID reader and motion sensors. Our proposed system helps in recognizing farming operations by analyzing the data from [...] Read more.
In order to automatically monitor farmers’ activities, we propose a farm operation monitoring system using “Field Servers” and a wearable device equipped with an RFID reader and motion sensors. Our proposed system helps in recognizing farming operations by analyzing the data from the sensors and detected RFID tags that are attached to various objects such as farming materials, facilities, and machinery. This method can be applied to various situations without changing the conventional system. Moreover, this system provides useful information in real-time and controls specific machines in a coordinated manner on the basis of recognized operation. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan)
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Open AccessArticle Amperometric Hydrogen Peroxide Biosensor Based on Immobilization of Hemoglobin on a Glassy Carbon Electrode Modified with Fe3O4/Chitosan Core-Shell Microspheres
Sensors 2009, 9(8), 6185-6199; doi:10.3390/s90806185
Received: 10 June 2009 / Revised: 23 July 2009 / Accepted: 3 August 2009 / Published: 5 August 2009
Cited by 22 | PDF Full-text (435 KB) | HTML Full-text | XML Full-text
Abstract
Novel magnetic Fe3O4/chitosan (CS) microspheres were prepared using magnetic Fe3O4 nanoparticles and the natural macromolecule chitosan. Then, using an easy and effective hemoglobin (Hb) immobilization method, an innovative biosensor with a Fe3O4 [...] Read more.
Novel magnetic Fe3O4/chitosan (CS) microspheres were prepared using magnetic Fe3O4 nanoparticles and the natural macromolecule chitosan. Then, using an easy and effective hemoglobin (Hb) immobilization method, an innovative biosensor with a Fe3O4/CS-Hb-Fe3O4/CS “sandwich” configuration was constructed. This biosensor had a fast (less than 10 s) response to H2O2 and excellent linear relationships were obtained in the concentration range of 5.0 × 10-5 to 1.8 × 10-3 M and 1.8 × 10-3 to 6.8 × 10-3 M with a detection limit of 4.0 × 10-6 M (s/n = 3) under the optimum conditions. The apparent Michaelis-Menten constant Km was 0.29 mM and it showed the excellent biological activity of the fixed Hb. Moreover, the biosensor had long-time stability and good reproducibility. The method was used to determine H2O2 concentration in real samples. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists
Sensors 2009, 9(8), 6200-6218; doi:10.3390/s90806200
Received: 30 June 2009 / Revised: 27 July 2009 / Accepted: 3 August 2009 / Published: 5 August 2009
Cited by 13 | PDF Full-text (1801 KB) | HTML Full-text | XML Full-text
Abstract
A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were [...] Read more.
A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of -0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of -0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification -0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm3 which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Manufacture of Micromirror Arrays Using a CMOS-MEMS Technique
Sensors 2009, 9(8), 6219-6231; doi:10.3390/s90806219
Received: 29 June 2009 / Revised: 25 July 2009 / Accepted: 3 August 2009 / Published: 6 August 2009
Cited by 2 | PDF Full-text (452 KB) | HTML Full-text | XML Full-text
Abstract
In this study we used the commercial 0.35 µm CMOS (complementary metal oxide semiconductor) process and simple maskless post-processing to fabricate an array of micromirrors exhibiting high natural frequency. The micromirrors were manufactured from aluminum; the sacrificial layer was silicon dioxide. Because [...] Read more.
In this study we used the commercial 0.35 µm CMOS (complementary metal oxide semiconductor) process and simple maskless post-processing to fabricate an array of micromirrors exhibiting high natural frequency. The micromirrors were manufactured from aluminum; the sacrificial layer was silicon dioxide. Because we fabricated the micromirror arrays using the standard CMOS process, they have the potential to be integrated with circuitry on a chip. For post-processing we used an etchant to remove the sacrificial layer and thereby suspend the micromirrors. The micromirror array contained a circular membrane and four fixed beams set symmetrically around and below the circular mirror; these four fan-shaped electrodes controlled the tilting of the micromirror. A MEMS (microelectromechanical system) motion analysis system and a confocal 3D-surface topography were used to characterize the properties and configuration of the micromirror array. Each micromirror could be rotated in four independent directions. Experimentally, we found that the micromirror had a tilting angle of about 2.55° when applying a driving voltage of 40 V. The natural frequency of the micromirrors was 59.1 kHz. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessCommunication Determination of Glucose Concentration in Aqueous Solution Using ATR-WT-IR Technique
Sensors 2009, 9(8), 6254-6260; doi:10.3390/s90806254
Received: 20 July 2009 / Revised: 30 July 2009 / Accepted: 3 August 2009 / Published: 6 August 2009
Cited by 3 | PDF Full-text (225 KB) | HTML Full-text | XML Full-text
Abstract
Fourier transformation infrared (FT-IR) spectroscopy has been used to measure glucose concentrations in different matrices. The accuracy of the FT-IR technique does not meet the requirements of medical applications, so we have developed a new, efficient and precise method based on attenuated [...] Read more.
Fourier transformation infrared (FT-IR) spectroscopy has been used to measure glucose concentrations in different matrices. The accuracy of the FT-IR technique does not meet the requirements of medical applications, so we have developed a new, efficient and precise method based on attenuated total reflectance coupled with wavelet transformation (ATR-WT-IR). One thousand interferograms, divided into training- and testing-sets, have been recorded from four glucose concentrations using an ATR-IR unit. Signals were subjected to (WT) and neural network (NN) study in order to design correlation algorithm. The Pearson’s Correlation Coefficient (PCC) obtained by judging the predicted- against the real-concentrations was 0.9954, with a mean square error of 8.4e-005. The proposed ATR-WT-IR method shows efficiency in glucose prediction and could possibly to be integrated into a non-invasive monitoring technique. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Gas Sensor Based on Photonic Crystal Fibres in the 2ν3 and ν2 + 2ν3 Vibrational Bands of Methane
Sensors 2009, 9(8), 6261-6272; doi:10.3390/s90806261
Received: 10 July 2009 / Revised: 3 August 2009 / Accepted: 7 August 2009 / Published: 10 August 2009
Cited by 20 | PDF Full-text (727 KB) | HTML Full-text | XML Full-text
Abstract
In this work, methane detection is performed on the 2ν3 and ν2 + 2ν3 absorption bands in the Near-Infrared (NIR) wavelength region using an all-fibre optical sensor. Hollowcore photonic bandgap fibres (HC-PBFs) are employed as gas cells [...] Read more.
In this work, methane detection is performed on the 2ν3 and ν2 + 2ν3 absorption bands in the Near-Infrared (NIR) wavelength region using an all-fibre optical sensor. Hollowcore photonic bandgap fibres (HC-PBFs) are employed as gas cells due to their compactness, good integrability in optical systems and feasibility of long interaction lengths with gases. Sensing in the 2ν3 band of methane is demonstrated to achieve a detection limit one order of magnitude better than that of the ν2 + 2ν3 band. Finally, the filling time of a HC-PBF is demonstrated to be dependent on the fibre length and geometry. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
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Open AccessArticle Design and Implementation of a SecureWireless Mote-Based Medical Sensor Network
Sensors 2009, 9(8), 6273-6297; doi:10.3390/s90806273
Received: 1 July 2009 / Revised: 7 August 2009 / Accepted: 7 August 2009 / Published: 11 August 2009
Cited by 24 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
A medical sensor network can wirelessly monitor vital signs of humans, making it useful for long-term health care without sacrificing patient comfort and mobility. For such a network to be viable, its design must protect data privacy and authenticity given that medical [...] Read more.
A medical sensor network can wirelessly monitor vital signs of humans, making it useful for long-term health care without sacrificing patient comfort and mobility. For such a network to be viable, its design must protect data privacy and authenticity given that medical data are highly sensitive. We identify the unique security challenges of such a sensor network and propose a set of resource-efficient mechanisms to address these challenges. Our solution includes (1) a novel two-tier scheme for verifying the authenticity of patient data, (2) a secure key agreement protocol to set up shared keys between sensor nodes and base stations, and (3) symmetric encryption/decryption for protecting data confidentiality and integrity. We have implemented the proposed mechanisms on a wireless mote platform, and our results confirm their feasibility. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle Bacteriophage T4 Nanoparticles as Materials in Sensor Applications: Variables That Influence Their Organization and Assembly on Surfaces
Sensors 2009, 9(8), 6298-6311; doi:10.3390/s90806298
Received: 1 July 2009 / Revised: 21 July 2009 / Accepted: 10 August 2009 / Published: 12 August 2009
Cited by 23 | PDF Full-text (533 KB) | HTML Full-text | XML Full-text
Abstract
Bacteriophage T4 nanoparticles possess characteristics that make them ideal candidates as materials for sensors, particularly as sensor probes. Their surface can be modified, either through genetic engineering or direct chemical conjugation to display functional moieties such as antibodies or other proteins to [...] Read more.
Bacteriophage T4 nanoparticles possess characteristics that make them ideal candidates as materials for sensors, particularly as sensor probes. Their surface can be modified, either through genetic engineering or direct chemical conjugation to display functional moieties such as antibodies or other proteins to recognize a specific target. However, in order for T4 nanoparticles to be utilized as a sensor probe, it is necessary to understand and control the variables that determine their assembly and organization on a surface. The aim of this work is to discuss some of variables that we have identified as influencing the behavior of T4 nanoparticles on surfaces. The effect of pH, ionic strength, substrate characteristics, nanoparticle concentration and charge was addressed qualitatively using atomic force microscopy (AFM). Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle A Comparison of RBF Neural Network Training Algorithms for Inertial Sensor Based Terrain Classification
Sensors 2009, 9(8), 6312-6329; doi:10.3390/s90806312
Received: 13 May 2009 / Revised: 25 June 2009 / Accepted: 30 July 2009 / Published: 12 August 2009
Cited by 49 | PDF Full-text (668 KB) | HTML Full-text | XML Full-text
Abstract
This paper introduces a comparison of training algorithms of radial basis function (RBF) neural networks for classification purposes. RBF networks provide effective solutions in many science and engineering fields. They are especially popular in the pattern classification and signal processing areas. Several [...] Read more.
This paper introduces a comparison of training algorithms of radial basis function (RBF) neural networks for classification purposes. RBF networks provide effective solutions in many science and engineering fields. They are especially popular in the pattern classification and signal processing areas. Several algorithms have been proposed for training RBF networks. The Artificial Bee Colony (ABC) algorithm is a new, very simple and robust population based optimization algorithm that is inspired by the intelligent behavior of honey bee swarms. The training performance of the ABC algorithm is compared with the Genetic algorithm, Kalman filtering algorithm and gradient descent algorithm. In the experiments, not only well known classification problems from the UCI repository such as the Iris, Wine and Glass datasets have been used, but also an experimental setup is designed and inertial sensor based terrain classification for autonomous ground vehicles was also achieved. Experimental results show that the use of the ABC algorithm results in better learning than those of others. Full article
(This article belongs to the Special Issue Neural Networks and Sensors)
Open AccessArticle Spatio-Temporal Human Grip Force Analysis via Sensor Arrays
Sensors 2009, 9(8), 6330-6345; doi:10.3390/s90806330
Received: 1 July 2009 / Revised: 6 August 2009 / Accepted: 7 August 2009 / Published: 12 August 2009
Cited by 4 | PDF Full-text (982 KB) | HTML Full-text | XML Full-text
Abstract
This study describes a technique for measuring human grip forces exerted on a cylindrical object via a sensor array. Standardised resistor-based pressure sensor arrays for industrial and medical applications have been available for some time. We used a special 20 mm diameter [...] Read more.
This study describes a technique for measuring human grip forces exerted on a cylindrical object via a sensor array. Standardised resistor-based pressure sensor arrays for industrial and medical applications have been available for some time. We used a special 20 mm diameter grip rod that subjects could either move actively with their fingers in the horizontal direction or exert reactive forces against opposing forces generated in the rod by a linear motor. The sensor array film was attached to the rod by adhesive tape and covered approximately 45 cm2 of the rod surface. The sensor density was 4/cm2 with each sensor having a force resolution of 0.1 N. A scan across all sensors resulted in a corresponding frame containing force values at a frame repetition rate of 150/s. The force value of a given sensor was interpreted as a pixel value resulting in a false-colour image. Based on remote sensed image analysis an algorithm was developed to distinguish significant force-representing pixels from those affected by noise. This allowed tracking of the position of identified fingers in subsequent frames such that spatio-temporal grip force profiles for individual fingers could be derived. Moreover, the algorithm allowed simultaneous measurement of forces exerted without any constraints on the number of fingers or on the position of the fingers. The system is thus well suited for basic and clinical research in human physiology as well as for studies in psychophysics. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle High-Resolution Images with Minimum Energy Dissipation and Maximum Field-of-View in Camera-Based Wireless Multimedia Sensor Networks
Sensors 2009, 9(8), 6385-6410; doi:10.3390/s90806385
Received: 15 June 2009 / Revised: 17 July 2009 / Accepted: 17 August 2009 / Published: 19 August 2009
Cited by 8 | PDF Full-text (1272 KB) | HTML Full-text | XML Full-text
Abstract
High-resolution images with wide field of view are important in realizing many applications of wireless multimedia sensor networks. Previous works that generally use multi-tier topology and provide such images by increasing the capabilities of camera sensor nodes lead to an increase in [...] Read more.
High-resolution images with wide field of view are important in realizing many applications of wireless multimedia sensor networks. Previous works that generally use multi-tier topology and provide such images by increasing the capabilities of camera sensor nodes lead to an increase in network cost. On the other hand, the resulting energy consumption is a considerable issue that has not been seriously considered in previous works. In this paper, high-resolution images with wide field of view are generated without increasing the total cost of network and with minimum energy dissipation. This is achieved by using image stitching in WMSNs, designing a two-tier network topology with new structure, and proposing a camera selection algorithm. In the proposed two-tier structure, low cost camera sensor nodes are used only in the lower-tier and sensor nodes without camera are considered in the upper-tier which decreases total network cost as much as possible. Also, since a simplified image stitching method is implemented and a new algorithm for selecting active nodes is utilized, energy dissipation in the network is decreased by applying the proposed methods. The results of simulations supported the preceding statements. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
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Open AccessArticle Design of a Water Environment Monitoring System Based on Wireless Sensor Networks
Sensors 2009, 9(8), 6411-6434; doi:10.3390/s90806411
Received: 5 May 2009 / Revised: 10 August 2009 / Accepted: 10 August 2009 / Published: 19 August 2009
Cited by 47 | PDF Full-text (653 KB) | HTML Full-text | XML Full-text
Abstract
A water environmental monitoring system based on a wireless sensor network is proposed. It consists of three parts: data monitoring nodes, data base station and remote monitoring center. This system is suitable for the complex and large-scale water environment monitoring, such as [...] Read more.
A water environmental monitoring system based on a wireless sensor network is proposed. It consists of three parts: data monitoring nodes, data base station and remote monitoring center. This system is suitable for the complex and large-scale water environment monitoring, such as for reservoirs, lakes, rivers, swamps, and shallow or deep groundwaters. This paper is devoted to the explanation and illustration for our new water environment monitoring system design. The system had successfully accomplished the online auto-monitoring of the water temperature and pH value environment of an artificial lake. The system's measurement capacity ranges from 0 to 80 °C for water temperature, with an accuracy of ±0.5 °C; from 0 to 14 on pH value, with an accuracy of ±0.05 pH units. Sensors applicable to different water quality scenarios should be installed at the nodes to meet the monitoring demands for a variety of water environments and to obtain different parameters. The monitoring system thus promises broad applicability prospects. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessArticle Preparation of a Polypyrrole-Polyvinylsulphonate Composite Film Biosensor for Determination of Cholesterol Based on Entrapment of Cholesterol Oxidase
Sensors 2009, 9(8), 6435-6445; doi:10.3390/s90806435
Received: 10 July 2009 / Revised: 3 August 2009 / Accepted: 10 August 2009 / Published: 20 August 2009
Cited by 9 | PDF Full-text (258 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a novel amperometric cholesterol biosensor with immobilization of cholesterol oxidase on electrochemically polymerized polypyrrole–polyvinylsulphonate (PPy–PVS) films has been accomplished via the entrapment technique on the surface of a platinum electrode. Electropolymerization of pyrrole and polyvinylsulphonate on the Pt surface [...] Read more.
In this paper, a novel amperometric cholesterol biosensor with immobilization of cholesterol oxidase on electrochemically polymerized polypyrrole–polyvinylsulphonate (PPy–PVS) films has been accomplished via the entrapment technique on the surface of a platinum electrode. Electropolymerization of pyrrole and polyvinylsulphonate on the Pt surface was carried out by cyclic voltammetry between -1.0 and +2.0 V (vs. Ag/AgCl) at a scan rate of 100 mV upon the Pt electrode with an electrochemical cell containing pyrrole and polyvinylsulphonate. The amperometric determination is based on the electrochemical detection of H2O2 generated in the enzymatic reaction of cholesterol. Determination of cholesterol was carried out by the oxidation of enzymatically produced H2O2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 7.25 and 35 °C, respectively. The storage stability and operational stability of the enzyme electrode were also studied. The results show that 32% of the response current was retained after 19 activity assays. The prepared cholesterol biosensor retained 43% of initial activity after 45 days when stored in 0.1 M phosphate buffer solution at 4 °C. Full article
Open AccessArticle A Self-Referencing Intensity Based Polymer Optical Fiber Sensor for Liquid Detection
Sensors 2009, 9(8), 6446-6455; doi:10.3390/s90806446
Received: 25 June 2009 / Revised: 13 August 2009 / Accepted: 13 August 2009 / Published: 20 August 2009
Cited by 19 | PDF Full-text (806 KB) | HTML Full-text | XML Full-text
Abstract
A novel self-referencing fiber optic intensity sensor based on bending losses of a partially polished polymer optical fiber (POF) coupler is presented. The coupling ratio (K) depends on the external liquid in which the sensor is immersed. It is possible to distinguish [...] Read more.
A novel self-referencing fiber optic intensity sensor based on bending losses of a partially polished polymer optical fiber (POF) coupler is presented. The coupling ratio (K) depends on the external liquid in which the sensor is immersed. It is possible to distinguish between different liquids and to detect their presence. Experimental results for the most usual liquids found in industry, like water and oil, are given. K value increases up to 10% from the nominal value depending on the liquid. Sensor temperature dependence has also been studied for a range from 25 ºC (environmental condition) to 50 ºC. Any sector requiring liquid level measurements in flammable atmospheres can benefit from this intrinsically safe technology. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessArticle A Novel Design of Grooved Fibers for Fiber-Optic Localized Plasmon Resonance Biosensors
Sensors 2009, 9(8), 6456-6470; doi:10.3390/s90806456
Received: 31 May 2009 / Revised: 22 July 2009 / Accepted: 19 August 2009 / Published: 20 August 2009
Cited by 15 | PDF Full-text (1513 KB) | HTML Full-text | XML Full-text
Abstract
Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces have been modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated [...] Read more.
Bio-molecular recognition is detected by the unique optical properties of self-assembled gold nanoparticles on the unclad portions of an optical fiber whose surfaces have been modified with a receptor. To enhance the performance of the sensing platform, the sensing element is integrated with a microfluidic chip to reduce sample and reagent volume, to shorten response time and analysis time, as well as to increase sensitivity. The main purpose of the present study is to design grooves on the optical fiber for the FO-LPR microfluidic chip and investigate the effect of the groove geometry on the biochemical binding kinetics through simulations. The optical fiber is designed and termed as U-type or D-type based on the shape of the grooves. The numerical results indicate that the design of the D-type fiber exhibits efficient performance on biochemical binding. The grooves designed on the optical fiber also induce chaotic advection to enhance the mixing in the microchannel. The mixing patterns indicate that D-type grooves enhance the mixing more effectively than U-type grooves. D-type fiber with six grooves is the optimum design according to the numerical results. The experimental results show that the D-type fiber could sustain larger elongation than the U-type fiber. Furthermore, this study successfully demonstrates the feasibility of fabricating the grooved optical fibers by the femtosecond laser, and making a transmission-based FO-LPR probe for chemical sensing. The sensor resolution of the sensor implementing the D-type fiber modified by gold nanoparticles was 4.1 × 10-7 RIU, which is much more sensitive than that of U-type optical fiber (1.8 × 10-3 RIU). Full article
(This article belongs to the Special Issue Nanotechnological Advances in Biosensors)
Open AccessArticle A Unified Multi-Functional Dynamic Spectrum Access Framework: Tutorial, Theory and Multi-GHz Wideband Testbed
Sensors 2009, 9(8), 6530-6603; doi:10.3390/s90806530
Received: 20 April 2009 / Revised: 14 July 2009 / Accepted: 4 August 2009 / Published: 21 August 2009
Cited by 13 | PDF Full-text (2584 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
Dynamic spectrum access is a must-have ingredient for future sensors that are ideally cognitive. The goal of this paper is a tutorial treatment of wideband cognitive radio and radar—a convergence of (1) algorithms survey, (2) hardware platforms survey, (3) challenges for multi-function [...] Read more.
Dynamic spectrum access is a must-have ingredient for future sensors that are ideally cognitive. The goal of this paper is a tutorial treatment of wideband cognitive radio and radar—a convergence of (1) algorithms survey, (2) hardware platforms survey, (3) challenges for multi-function (radar/communications) multi-GHz front end, (4) compressed sensing for multi-GHz waveforms—revolutionary A/D, (5) machine learning for cognitive radio/radar, (6) quickest detection, and (7) overlay/underlay cognitive radio waveforms. One focus of this paper is to address the multi-GHz front end, which is the challenge for the next-generation cognitive sensors. The unifying theme of this paper is to spell out the convergence for cognitive radio, radar, and anti-jamming. Moore’s law drives the system functions into digital parts.From a system viewpoint, this paper gives the first comprehensive treatment for the functions and the challenges of this multi-function (wideband) system. This paper brings together the inter-disciplinary knowledge. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)

Review

Jump to: Research

Open AccessReview Meat Quality Assessment by Electronic Nose (Machine Olfaction Technology)
Sensors 2009, 9(8), 6058-6083; doi:10.3390/s90806058
Received: 7 June 2009 / Revised: 22 June 2009 / Accepted: 14 July 2009 / Published: 30 July 2009
Cited by 28 | PDF Full-text (492 KB) | HTML Full-text | XML Full-text
Abstract
Over the last twenty years, newly developed chemical sensor systems (so called “electronic noses”) have made odor analyses possible. These systems involve various types of electronic chemical gas sensors with partial specificity, as well as suitable statistical methods enabling the recognition of [...] Read more.
Over the last twenty years, newly developed chemical sensor systems (so called “electronic noses”) have made odor analyses possible. These systems involve various types of electronic chemical gas sensors with partial specificity, as well as suitable statistical methods enabling the recognition of complex odors. As commercial instruments have become available, a substantial increase in research into the application of electronic noses in the evaluation of volatile compounds in food, cosmetic and other items of everyday life is observed. At present, the commercial gas sensor technologies comprise metal oxide semiconductors, metal oxide semiconductor field effect transistors, organic conducting polymers, and piezoelectric crystal sensors. Further sensors based on fibreoptic, electrochemical and bi-metal principles are still in the developmental stage. Statistical analysis techniques range from simple graphical evaluation to multivariate analysis such as artificial neural network and radial basis function. The introduction of electronic noses into the area of food is envisaged for quality control, process monitoring, freshness evaluation, shelf-life investigation and authenticity assessment. Considerable work has already been carried out on meat, grains, coffee, mushrooms, cheese, sugar, fish, beer and other beverages, as well as on the odor quality evaluation of food packaging material. This paper describes the applications of these systems for meat quality assessment, where fast detection methods are essential for appropriate product management. The results suggest the possibility of using this new technology in meat handling. Full article
(This article belongs to the Special Issue Gas Sensors 2009)
Open AccessReview Mid-Infrared Sensing of Organic Pollutants in Aqueous Environments
Sensors 2009, 9(8), 6232-6253; doi:10.3390/s90806232
Received: 11 June 2009 / Revised: 24 July 2009 / Accepted: 4 August 2009 / Published: 6 August 2009
Cited by 22 | PDF Full-text (302 KB) | HTML Full-text | XML Full-text
Abstract
The development of chemical sensors for monitoring the levels of organic pollutants in the aquatic environment has received a great deal of attention in recent decades. In particular, the mid-infrared (MIR) sensor based on attenuated total reflectance (ATR) is a promising analytical [...] Read more.
The development of chemical sensors for monitoring the levels of organic pollutants in the aquatic environment has received a great deal of attention in recent decades. In particular, the mid-infrared (MIR) sensor based on attenuated total reflectance (ATR) is a promising analytical tool that has been used to detect a variety of hydrocarbon compounds (i.e., aromatics, alkyl halides, phenols, etc.) dissolved in water. It has been shown that under certain conditions the MIR-ATR sensor is capable of achieving detection limits in the 10-100 ppb concentration range. Since the infrared spectral features of every single organic molecule are unique, the sensor is highly selective, making it possible to distinguish between many different analytes simultaneously. This review paper discusses some of the parameters (i.e., membrane type, film thickness, conditioning) that dictate MIR ATR sensor response. The performance of various chemoselective membranes which are used in the fabrication of the sensor will be evaluated. Some of the challenges associated with long-term environmental monitoring are also discussed. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Recent Findings Concerning PAMAM Dendrimer Conjugates with Cyclodextrins as Carriers of DNA and RNA
Sensors 2009, 9(8), 6346-6361; doi:10.3390/s90806346
Received: 2 July 2009 / Revised: 6 August 2009 / Accepted: 7 August 2009 / Published: 17 August 2009
Cited by 28 | PDF Full-text (636 KB) | HTML Full-text | XML Full-text
Abstract
We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree [...] Read more.
We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree of substitution (DS) of 2.4 [α-CDE (G3, DS2)] displayed remarkable properties as DNA, shRNA and siRNA delivery carriers through the sensor function of α-CDEs toward nucleic acid drugs, cell surface and endosomal membranes. In an attempt to develop cell-specific gene transfer carriers, we prepared sugar-appended α-CDEs. Of the various sugar-appended α-CDEs prepared, galactose- or mannose-appended α-CDEs provided superior gene transfer activity to α-CDE in various cells, but not cell-specific gene delivery ability. However, lactose-appended α-CDE [Lac-α-CDE (G2)] was found to possess asialoglycoprotein receptor (AgpR)-mediated hepatocyte-selective gene transfer activity, both in vitro and in vivo. Most recently, we prepared folate-poly(ethylene glycol)-appended α-CDE [Fol-PαC (G3)] and revealed that Fol-PαC (G3) imparted folate receptor (FR)-mediated cancer cell-selective gene transfer activity. Consequently, α-CDEs bearing integrated, multifunctional molecules may possess the potential to be novel carriers for DNA, shRNA and siRNA. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessReview Piezoelectric and Magnetoelectric Thick Films for Fabricating Power Sources in Wireless Sensor Nodes
Sensors 2009, 9(8), 6362-6384; doi:10.3390/s90806362
Received: 23 July 2009 / Revised: 10 August 2009 / Accepted: 11 August 2009 / Published: 17 August 2009
Cited by 43 | PDF Full-text (1578 KB) | HTML Full-text | XML Full-text
Abstract
In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3 (PZNT) have [...] Read more.
In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O3–Pb(Zn1/3Nb2/3)O3 (PZNT) have shown promise for providing enhanced efficiency due to higher energy density and thus form the base of transducers designed for capturing the mechanical energy. Laminate structures of PZNT with magnetostrictive ferrite materials provide large magnitudes of magnetoelectric coupling and are being targeted to capture the stray magnetic field energy. We analyze the models used to predict the performance of the energy harvesters and present a full system description. Full article
(This article belongs to the Special Issue Wireless Sensor Technologies and Applications)
Open AccessReview Exploiting Surface Plasmon Resonance (SPR) Technology for the Identification of Fibroblast Growth Factor-2 (FGF2) Antagonists Endowed with Antiangiogenic Activity
Sensors 2009, 9(8), 6471-6503; doi:10.3390/s90806471
Received: 24 July 2009 / Revised: 17 August 2009 / Accepted: 19 August 2009 / Published: 20 August 2009
Cited by 10 | PDF Full-text (780 KB) | HTML Full-text | XML Full-text
Abstract
Angiogenesis, the process of new blood vessel formation, is implicated in various physiological/pathological conditions, including embryonic development, inflammation and tumor growth. Fibroblast growth factor-2 (FGF2) is a heparin-binding angiogenic growth factor involved in various physiopathological processes, including tumor neovascularization. Accordingly, FGF2 is [...] Read more.
Angiogenesis, the process of new blood vessel formation, is implicated in various physiological/pathological conditions, including embryonic development, inflammation and tumor growth. Fibroblast growth factor-2 (FGF2) is a heparin-binding angiogenic growth factor involved in various physiopathological processes, including tumor neovascularization. Accordingly, FGF2 is considered a target for antiangiogenic therapies. Thus, numerous natural/synthetic compounds have been tested for their capacity to bind and sequester FGF2 in the extracellular environment preventing its interaction with cellular receptors. We have exploited surface plasmon resonance (SPR) technique in search for antiangiogenic FGF2 binders/antagonists. In this review we will summarize our experience in SPR-based angiogenesis research, with the aim to validate SPR as a first line screening for the identification of antiangiogenic compounds. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy)
Open AccessReview A Comprehensive Review of One-Dimensional Metal-Oxide Nanostructure Photodetectors
Sensors 2009, 9(8), 6504-6529; doi:10.3390/s90806504
Received: 14 July 2009 / Revised: 5 August 2009 / Accepted: 19 August 2009 / Published: 20 August 2009
Cited by 223 | PDF Full-text (5049 KB) | HTML Full-text | XML Full-text
Abstract
One-dimensional (1D) metal-oxide nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating size and dimensionality dependence of nanostructure properties for potential applications. The construction and integration of photodetectors or optical switches based on such [...] Read more.
One-dimensional (1D) metal-oxide nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating size and dimensionality dependence of nanostructure properties for potential applications. The construction and integration of photodetectors or optical switches based on such nanostructures with tailored geometries have rapidly advanced in recent years. Active 1D nanostructure photodetector elements can be configured either as resistors whose conductions are altered by a charge-transfer process or as field-effect transistors (FET) whose properties can be controlled by applying appropriate potentials onto the gates. Functionalizing the structure surfaces offers another avenue for expanding the sensor capabilities. This article provides a comprehensive review on the state-of-the-art research activities in the photodetector field. It mainly focuses on the metal oxide 1D nanostructures such as ZnO, SnO2, Cu2O, Ga2O3, Fe2O3, In2O3, CdO, CeO2, and their photoresponses. The review begins with a survey of quasi 1D metal-oxide semiconductor nanostructures and the photodetector principle, then shows the recent progresses on several kinds of important metal-oxide nanostructures and their photoresponses and briefly presents some additional prospective metal-oxide 1D nanomaterials. Finally, the review is concluded with some perspectives and outlook on the future developments in this area. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)

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