Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Sensors, Volume 10, Issue 9 (September 2010), Pages 7896-8781

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-54
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Effective Fingerprint Quality Estimation for Diverse Capture Sensors
Sensors 2010, 10(9), 7896-7912; doi:10.3390/s100907896
Received: 8 June 2010 / Revised: 2 July 2010 / Accepted: 11 August 2010 / Published: 26 August 2010
Cited by 7 | PDF Full-text (874 KB) | HTML Full-text | XML Full-text
Abstract
Recognizing the quality of fingerprints in advance can be beneficial for improving the performance of fingerprint recognition systems. The representative features to assess the quality of fingerprint images from different types of capture sensors are known to vary. In this paper, an effective
[...] Read more.
Recognizing the quality of fingerprints in advance can be beneficial for improving the performance of fingerprint recognition systems. The representative features to assess the quality of fingerprint images from different types of capture sensors are known to vary. In this paper, an effective quality estimation system that can be adapted for different types of capture sensors is designed by modifying and combining a set of features including orientation certainty, local orientation quality and consistency. The proposed system extracts basic features, and generates next level features which are applicable for various types of capture sensors. The system then uses the Support Vector Machine (SVM) classifier to determine whether or not an image should be accepted as input to the recognition system. The experimental results show that the proposed method can perform better than previous methods in terms of accuracy. In the meanwhile, the proposed method has an ability to eliminate residue images from the optical and capacitive sensors, and the coarse images from thermal sensors. Full article
(This article belongs to the Special Issue Bioinspired Sensor Systems)
Figures

Open AccessArticle Sensory Evaluation of Pralines Containing Different Honey Products
Sensors 2010, 10(9), 7913-7933; doi:10.3390/s100907913
Received: 28 June 2010 / Revised: 22 July 2010 / Accepted: 3 August 2010 / Published: 26 August 2010
Cited by 4 | PDF Full-text (373 KB) | HTML Full-text | XML Full-text
Abstract
In this study, pralines manufactured by hand were evaluated sensorially. These pralines were obtained from dark chocolate containing 60% cocoa components, filled with Apis mellifera carnica Poll drone larvae, blossom honey and a blossom honey/pollen mixture from the protected region of Stara Planina-Eastern
[...] Read more.
In this study, pralines manufactured by hand were evaluated sensorially. These pralines were obtained from dark chocolate containing 60% cocoa components, filled with Apis mellifera carnica Poll drone larvae, blossom honey and a blossom honey/pollen mixture from the protected region of Stara Planina-Eastern Serbia (a specific botanical region). The objectives of this study were investigations related to the use of sensory analysis for quality assessment of new functional products with potential benefits for human health, in particular of desserts based on dark chocolate pralines filled with different bee products characterized by a specific botanical and geographic origin, as well as of their storage properties and expected shelf life. Sensory quality (appearance, texture, odor and taste were evaluated by a group of experienced panelists immediately after the production (day 0), and then after 30, 90 and 180 days of storage under ambient conditions (temperature 18–20 ºC). The results were statistically analyzed by the two-factorial analysis of variance (MANOVA) and with the LSD-test. It is possible to conclude that the storage time and composition of dark chocolate pralines containing different honey-bee products have statistically highly significant (p < 0.01) influence on the sensorially evaluated properties of pralines. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Flexible Temperature Sensors on Fibers
Sensors 2010, 10(9), 7934-7946; doi:10.3390/s100907934
Received: 28 June 2010 / Revised: 26 July 2010 / Accepted: 2 August 2010 / Published: 26 August 2010
Cited by 42 | PDF Full-text (434 KB) | HTML Full-text | XML Full-text
Abstract
The aim of this paper is to present research dedicated to the elaboration of novel, miniaturized flexible temperature sensors for textronic applications. Examined sensors were manufactured on a single yarn, which ensures their high flexibility and good compatibility with textiles. Stable and linear
[...] Read more.
The aim of this paper is to present research dedicated to the elaboration of novel, miniaturized flexible temperature sensors for textronic applications. Examined sensors were manufactured on a single yarn, which ensures their high flexibility and good compatibility with textiles. Stable and linear characteristics were obtained by special technological process and applied temperature profiles. As a thermo-sensitive materials the innovative polymer compositions filled with multiwalled carbon nanotubes were used. Elaborated material was adapted to printing and dip-coating techniques to produce NTC composites. Nanotube sensors were free from tensometric effect typical for other carbon-polymer sensor, and demonstrated TCR of 0.13%/K. Obtained temperature sensors, compatible with textile structure, can be applied in rapidly developing smart textiles and be used for health and protections purposes. Full article
Figures

Open AccessArticle A Fluorescent Thermometer Based on a Pyrene-Labeled Thermoresponsive Polymer
Sensors 2010, 10(9), 7979-7990; doi:10.3390/s100907979
Received: 21 June 2010 / Revised: 23 July 2010 / Accepted: 20 August 2010 / Published: 27 August 2010
Cited by 33 | PDF Full-text (284 KB) | HTML Full-text | XML Full-text
Abstract
Thermoresponsive polymers that undergo a solubility transition by variation of the temperature are important materials for the development of ‘smart’ materials. In this contribution we exploit the solubility phase transition of poly(methoxy diethylene glycol methacrylate), which is accompanied by a transition from hydrophilic
[...] Read more.
Thermoresponsive polymers that undergo a solubility transition by variation of the temperature are important materials for the development of ‘smart’ materials. In this contribution we exploit the solubility phase transition of poly(methoxy diethylene glycol methacrylate), which is accompanied by a transition from hydrophilic to hydrophobic, for the development of a fluorescent thermometer. To translate the polymer phase transition into a fluorescent response, the polymer was functionalized with pyrene resulting in a change of the emission based on the microenvironment. This approach led to a soluble polymeric fluorescent thermometer with a temperature range from 11 °C to 21 °C. The polymer phase transition that occurs during sensing is studied in detail by dynamic light scattering. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in The Netherlands)
Figures

Open AccessArticle Using RFID to Enhance Security in Off-Site Data Storage
Sensors 2010, 10(9), 8010-8027; doi:10.3390/s100908010
Received: 30 June 2010 / Revised: 17 August 2010 / Accepted: 26 August 2010 / Published: 27 August 2010
Cited by 2 | PDF Full-text (524 KB) | HTML Full-text | XML Full-text
Abstract
Off-site data storage is one of the most widely used strategies in enterprises of all sizes to improve business continuity. In medium-to-large size enterprises, the off-site data storage processes are usually outsourced to specialized providers. However, outsourcing the storage of critical business information
[...] Read more.
Off-site data storage is one of the most widely used strategies in enterprises of all sizes to improve business continuity. In medium-to-large size enterprises, the off-site data storage processes are usually outsourced to specialized providers. However, outsourcing the storage of critical business information assets raises serious security considerations, some of which are usually either disregarded or incorrectly addressed by service providers. This article reviews these security considerations and presents a radio frequency identification (RFID)-based, off-site, data storage management system specifically designed to address security issues. The system relies on a set of security mechanisms or controls that are arranged in security layers or tiers to balance security requirements with usability and costs. The system has been successfully implemented, deployed and put into production. In addition, an experimental comparison with classical bar-code-based systems is provided, demonstrating the system’s benefits in terms of efficiency and failure prevention. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle Identifying and Tracking Pedestrians Based on Sensor Fusion and Motion Stability Predictions
Sensors 2010, 10(9), 8028-8053; doi:10.3390/s100908028
Received: 1 July 2010 / Revised: 9 August 2010 / Accepted: 26 August 2010 / Published: 27 August 2010
Cited by 20 | PDF Full-text (1800 KB) | HTML Full-text | XML Full-text
Abstract
The lack of trustworthy sensors makes development of Advanced Driver Assistance System (ADAS) applications a tough task. It is necessary to develop intelligent systems by combining reliable sensors and real-time algorithms to send the proper, accurate messages to the drivers. In this article,
[...] Read more.
The lack of trustworthy sensors makes development of Advanced Driver Assistance System (ADAS) applications a tough task. It is necessary to develop intelligent systems by combining reliable sensors and real-time algorithms to send the proper, accurate messages to the drivers. In this article, an application to detect and predict the movement of pedestrians in order to prevent an imminent collision has been developed and tested under real conditions. The proposed application, first, accurately measures the position of obstacles using a two-sensor hybrid fusion approach: a stereo camera vision system and a laser scanner. Second, it correctly identifies pedestrians using intelligent algorithms based on polylines and pattern recognition related to leg positions (laser subsystem) and dense disparity maps and u-v disparity (vision subsystem). Third, it uses statistical validation gates and confidence regions to track the pedestrian within the detection zones of the sensors and predict their position in the upcoming frames. The intelligent sensor application has been experimentally tested with success while tracking pedestrians that cross and move in zigzag fashion in front of a vehicle. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Figures

Open AccessArticle Energy-Efficient and Fast Data Gathering Protocols for Indoor Wireless Sensor Networks
Sensors 2010, 10(9), 8054-8069; doi:10.3390/s100908054
Received: 20 July 2010 / Revised: 5 August 2010 / Accepted: 10 August 2010 / Published: 27 August 2010
Cited by 16 | PDF Full-text (666 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks have become an important technology with numerous potential applications for the interaction of computers and the physical environment in civilian and military areas. In the routing protocols that are specifically designed for the applications used by sensor networks, the limited
[...] Read more.
Wireless Sensor Networks have become an important technology with numerous potential applications for the interaction of computers and the physical environment in civilian and military areas. In the routing protocols that are specifically designed for the applications used by sensor networks, the limited available power of the sensor nodes has been taken into consideration in order to extend the lifetime of the networks. In this paper, two protocols based on LEACH and called R-EERP and S-EERP with base and threshold values are presented. R-EERP and S-EERP are two efficient energy aware routing protocols that can be used for some critical applications such as detecting dangerous gases (methane, ammonium, carbon monoxide, etc.) in an indoor environment. In R-EERP, sensor nodes are deployed randomly in a field similar to LEACH. In S-EERP, nodes are deployed sequentially in the rooms of the flats of a multi-story building. In both protocols, nodes forming clusters do not change during a cluster change time, only the cluster heads change. Furthermore, an XOR operation is performed on the collected data in order to prevent the sending of the same data sensed by the nodes close to each other. Simulation results show that our proposed protocols are more energy-efficient than the conventional LEACH protocol. Full article
Figures

Open AccessArticle Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach
Sensors 2010, 10(9), 8070-8091; doi:10.3390/s100908070
Received: 2 July 2010 / Revised: 27 July 2010 / Accepted: 13 August 2010 / Published: 27 August 2010
Cited by 3 | PDF Full-text (445 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must
[...] Read more.
In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. Full article
(This article belongs to the Special Issue Intelligent Sensors)
Figures

Open AccessCommunication Real-Time Particle Mass Spectrometry Based on Resonant Micro Strings
Sensors 2010, 10(9), 8092-8100; doi:10.3390/s100908092
Received: 10 July 2010 / Revised: 30 July 2010 / Accepted: 15 August 2010 / Published: 27 August 2010
Cited by 34 | PDF Full-text (7620 KB) | HTML Full-text | XML Full-text
Abstract
Micro- and nanomechanical resonators are widely being used as mass sensors due to their unprecedented mass sensitivity. We present a simple closed-form expression which allows a fast and quantitative calculation of the position and mass of individual particles placed on a micro or
[...] Read more.
Micro- and nanomechanical resonators are widely being used as mass sensors due to their unprecedented mass sensitivity. We present a simple closed-form expression which allows a fast and quantitative calculation of the position and mass of individual particles placed on a micro or nano string by measuring the resonant frequency shifts ofthe first two bending modes. The method has been tested by detecting the mass spectrum of micro particles placed on a micro string. This method enables real-time mass spectrometry necessary for applications such as personal monitoring devices for the assessment of theexposure dose of airborne nanoparticles. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle An Efficient Lagrangean Relaxation-based Object Tracking Algorithm in Wireless Sensor Networks
Sensors 2010, 10(9), 8101-8118; doi:10.3390/s100908101
Received: 17 June 2010 / Revised: 12 August 2010 / Accepted: 18 August 2010 / Published: 27 August 2010
PDF Full-text (329 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we propose an energy-efficient object tracking algorithm in wireless sensor networks (WSNs). Such sensor networks have to be designed to achieve energy-efficient object tracking for any given arbitrary topology. We consider in particular the bi-directional moving objects with given frequencies
[...] Read more.
In this paper we propose an energy-efficient object tracking algorithm in wireless sensor networks (WSNs). Such sensor networks have to be designed to achieve energy-efficient object tracking for any given arbitrary topology. We consider in particular the bi-directional moving objects with given frequencies for each pair of sensor nodes and link transmission cost. This problem is formulated as a 0/1 integer-programming problem. A Lagrangean relaxation-based (LR-based) heuristic algorithm is proposed for solving the optimization problem. Experimental results showed that the proposed algorithm achieves near optimization in energy-efficient object tracking. Furthermore, the algorithm is very efficient and scalable in terms of the solution time. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle A Magnetostrictive Composite-Fiber Bragg Grating Sensor
Sensors 2010, 10(9), 8119-8128; doi:10.3390/s100908119
Received: 10 July 2010 / Revised: 30 July 2010 / Accepted: 15 August 2010 / Published: 30 August 2010
Cited by 25 | PDF Full-text (805 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the
[...] Read more.
This paper presents a light and compact optical fiber Bragg Grating sensor for DC and AC magnetic field measurements. The fiber is coated by a thick layer of a magnetostrictive composite consisting of particles of Terfenol-D dispersed in a polymeric matrix. Among the different compositions for the coating that were tested, the best magnetostrictive response was obtained using an epoxy resin as binder and a 30% volume fraction of Terfenol-D particles with sizes ranging from 212 to 300 µm. The effect of a compressive preload in the sensor was also investigated. The achieved resolution was 0.4 mT without a preload or 0.3 mT with a compressive pre-stress of 8.6 MPa. The sensor was tested at magnetic fields of up to 750 mT under static conditions. Dynamic measurements were conducted with a magnetic unbalanced four-pole rotor Full article
(This article belongs to the Special Issue Advanced Embedded Sensors)
Figures

Open AccessCommunication A Novel Sensing Method and Sensing Algorithm Development for a Ubiquitous Network
Sensors 2010, 10(9), 8129-8142; doi:10.3390/s100908129
Received: 15 July 2010 / Revised: 30 July 2010 / Accepted: 15 August 2010 / Published: 30 August 2010
Cited by 6 | PDF Full-text (1018 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a novel technique which provides energy efficient circuit design for sensors networks. The overall system presented requires a minimum number of independently communicating sensors and sub-circuits which enable it to reduce the power consumption by setting unused sensors to idle.
[...] Read more.
This paper proposes a novel technique which provides energy efficient circuit design for sensors networks. The overall system presented requires a minimum number of independently communicating sensors and sub-circuits which enable it to reduce the power consumption by setting unused sensors to idle. This technique reduces hardware requirements, time and interconnection problems with a supervisory control. Our proposed algorithm, which hands over the controls to two software mangers for the sensing and moving subsystems can greatly improve the overall system performance. Based on the experimental results, we observed that our system, which is using sensing and moving managers, the four sensors required only 3.4 mW power consumption when a robot arm is moved a total distance of 17 cm. This system is designed for robot applications but could be implemented to many other human environments such as “ubiquitous cities”, “smart homes”, etc. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle The Structure of Ca2+ Sensor Case16 Reveals the Mechanism of Reaction to Low Ca2+ Concentrations
Sensors 2010, 10(9), 8143-8160; doi:10.3390/s100908143
Received: 25 June 2010 / Revised: 28 July 2010 / Accepted: 12 August 2010 / Published: 30 August 2010
Cited by 9 | PDF Full-text (1175 KB) | HTML Full-text | XML Full-text
Abstract
Here we report the first crystal structure of a high-contrast genetically encoded circularly permuted green fluorescent protein (cpGFP)-based Ca2+ sensor, Case16, in the presence of a low Ca2+ concentration. The structure reveals the positioning of the chromophore within Case16 at the
[...] Read more.
Here we report the first crystal structure of a high-contrast genetically encoded circularly permuted green fluorescent protein (cpGFP)-based Ca2+ sensor, Case16, in the presence of a low Ca2+ concentration. The structure reveals the positioning of the chromophore within Case16 at the first stage of the Ca2+-dependent response when only two out of four Ca2+-binding pockets of calmodulin (CaM) are occupied with Ca2+ ions. In such a “half Ca2+-bound state”, Case16 is characterized by an incomplete interaction between its CaM-/M13-domains. We also report the crystal structure of the related Ca2+ sensor Case12 at saturating Ca2+ concentration. Based on this structure, we postulate that cpGFP-based Ca2+ sensors can form non-functional homodimers where the CaM-domain of one sensor molecule binds symmetrically to the M13-peptide of the partner sensor molecule. Case12 and Case16 behavior upon addition of high concentrations of free CaM or M13-peptide reveals that the latter effectively blocks the fluorescent response of the sensor. We speculate that the demonstrated intermolecular interaction with endogenous substrates and homodimerization can impede proper functioning of this type of Ca2+ sensors in living cells. Full article
(This article belongs to the Section Biosensors)
Figures

Open AccessArticle Applications of Ferro-Nanofluid on a Micro-Transformer
Sensors 2010, 10(9), 8161-8172; doi:10.3390/s100908161
Received: 8 June 2010 / Revised: 20 August 2010 / Accepted: 20 August 2010 / Published: 31 August 2010
Cited by 20 | PDF Full-text (1333 KB) | HTML Full-text | XML Full-text
Abstract
An on-chip transformer with a ferrofluid magnetic core has been developed and tested. The transformer consists of solenoid-type coil and a magnetic core of ferrofluid, with the former fabricated by MEMS technology and the latter by a chemical co-precipitation method. The performance of
[...] Read more.
An on-chip transformer with a ferrofluid magnetic core has been developed and tested. The transformer consists of solenoid-type coil and a magnetic core of ferrofluid, with the former fabricated by MEMS technology and the latter by a chemical co-precipitation method. The performance of the MEMS transformer with a ferrofluid magnetic core was measured and simulated with frequencies ranging from 100 kHz to 100 MHz. Experimental results reveal that the presence of the ferrofluid increases the inductance of coils and the coupling coefficient of transformer; however, it also increases the resistance owing to the lag between the external magnetic field and the magnetization of the material. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Micro Cantilever Movement Detection with an Amorphous Silicon Array of Position Sensitive Detectors
Sensors 2010, 10(9), 8173-8184; doi:10.3390/s100908173
Received: 23 June 2010 / Revised: 30 July 2010 / Accepted: 30 August 2010 / Published: 1 September 2010
Cited by 6 | PDF Full-text (669 KB) | HTML Full-text | XML Full-text
Abstract
The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform
[...] Read more.
The movement of a micro cantilever was detected via a self constructed portable data acquisition prototype system which integrates a linear array of 32 1D amorphous silicon position sensitive detectors (PSD). The system was mounted on a microscope using a metal structure platform and the movement of the 30  µm wide by 400  µm long cantilever was tracked by analyzing the signals acquired by the 32 sensor array electronic readout system and the relevant data algorithm. The obtained results show a linear behavior of the photocurrent relating X and Y movement, with a non-linearity of about 3%, a spatial resolution of less than 2 µm along the lateral dimension of the sensor as well as of less than 3 µm along the perpendicular dimension of the sensor, when detecting just the micro-cantilever, and a spatial resolution of less than 1 µm when detecting the holding structure. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessArticle Odours Influence Visually Induced Emotion: Behavior and Neuroimaging
Sensors 2010, 10(9), 8185-8197; doi:10.3390/s100908185
Received: 28 July 2010 / Revised: 26 August 2010 / Accepted: 31 August 2010 / Published: 1 September 2010
Cited by 8 | PDF Full-text (301 KB) | HTML Full-text | XML Full-text
Abstract
The present study was conducted to investigate the influence of olfaction on subjective valence intensity ratings of visual presentations. Pictures of five different categories (baby, flower, erotic, fear and disgust) were presented each being associated with five different odour conditions [no
[...] Read more.
The present study was conducted to investigate the influence of olfaction on subjective valence intensity ratings of visual presentations. Pictures of five different categories (baby, flower, erotic, fear and disgust) were presented each being associated with five different odour conditions [no odour, low and high concentrations of phenylethyl alcohol (positive odour) and low and high concentrations of hydrogen sulphide (negative odour)]. Study participants had to rate the emotional content of each picture with respect to valence and intensity while brain activities were recorded with a whole-cortex magnetoencephalograph (MEG). A significant interaction between odour condition and picture category with respect to rating performance was found. In particular, positive valence intensity ratings related to flowers were increased in positive and negative odour conditions. Negative valence intensity ratings related to disgusting pictures were also increased in positive and negative odour conditions. The only decrease was found in the baby category in the high concentration negative odour condition. No behavioural effects were found for the categories erotic and fear. Around 300 ms after stimulus onset odour-related brain activity effects were found for all picture categories. On the other hand, around 700 ms after stimulus onset odour-related brain activity effects occurred only in the flower, fear and disgust picture categories. We interpret that early information processing demonstrates more pronounced olfactory and visually induced emotion interaction than later information processing. Since the early time window more likely reflects subconscious information processing we interpret that interaction between olfaction and visually induced emotion mostly occurs below the level of consciousness. Later, rather conscious information processing, seems to be differently influenced by simultaneous olfaction depending on the kind of emotion elicited through the sense of vision. Full article
(This article belongs to the Special Issue Direct and Indirect Sensing of Odor and VOCs and Their Control)
Figures

Open AccessArticle Assessment of Relative Accuracy of AHN-2 Laser Scanning Data Using Planar Features
Sensors 2010, 10(9), 8198-8214; doi:10.3390/s100908198
Received: 20 July 2010 / Revised: 19 August 2010 / Accepted: 20 August 2010 / Published: 1 September 2010
Cited by 33 | PDF Full-text (1300 KB) | HTML Full-text | XML Full-text
Abstract
AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements, often points
[...] Read more.
AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip adjustment and accuracy assessment of AHN-2 data by using planar features. In the proposed approach a transformation is estimated between two overlapping strips by minimizing the distances between points in one strip and their corresponding planes in the other. The planes and the corresponding points are extracted in an automated segmentation process. The point-to-plane distances are used as observables in an estimation model, whereby the parameters of a transformation between the two strips and their associated quality measures are estimated. We demonstrate the performance of the method for the accuracy assessment of the AHN-2 dataset over Zeeland province of The Netherlands. The results show vertical offsets of up to 4 cm between the overlapping strips, and horizontal offsets ranging from 2 cm to 34 cm. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in The Netherlands)
Figures

Open AccessArticle Study of a QCM Dimethyl Methylphosphonate Sensor Based on a ZnO-Modified Nanowire-Structured Manganese Dioxide Film
Sensors 2010, 10(9), 8275-8290; doi:10.3390/s100908275
Received: 10 August 2010 / Revised: 20 August 2010 / Accepted: 31 August 2010 / Published: 2 September 2010
Cited by 17 | PDF Full-text (767 KB) | HTML Full-text | XML Full-text
Abstract
Sensitive, selective and fast detection of chemical warfare agents is necessary for anti-terrorism purposes. In our search for functional materials sensitive to dimethyl methylphosphonate (DMMP), a simulant of sarin and other toxic organophosphorus compounds, we found that zinc oxide (ZnO) modification potentially enhances
[...] Read more.
Sensitive, selective and fast detection of chemical warfare agents is necessary for anti-terrorism purposes. In our search for functional materials sensitive to dimethyl methylphosphonate (DMMP), a simulant of sarin and other toxic organophosphorus compounds, we found that zinc oxide (ZnO) modification potentially enhances the absorption of DMMP on a manganese dioxide (MnO2) surface. The adsorption behavior of DMMP was evaluated through the detection of tiny organophosphonate compounds with quartz crystal microbalance (QCM) sensors coated with ZnO-modified MnO2 nanofibers and pure MnO2 nanofibers. Experimental results indicated that the QCM sensor coated with ZnO-modified nanostructured MnO2 film exhibited much higher sensitivity and better selectivity in comparison with the one coated with pure MnO2 nanofiber film. Therefore, the DMMP sensor developed with this composite nanostructured material should possess excellent selectivity and reasonable sensitivity towards the tiny gaseous DMMP species. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
Open AccessArticle A Flexible Strain Sensor Based on a Conductive Polymer Composite for in situ Measurement of Parachute Canopy Deformation
Sensors 2010, 10(9), 8291-8303; doi:10.3390/s100908291
Received: 15 July 2010 / Revised: 5 August 2010 / Accepted: 25 August 2010 / Published: 2 September 2010
Cited by 21 | PDF Full-text (1177 KB) | HTML Full-text | XML Full-text
Abstract
A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000
[...] Read more.
A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Modeling and Experimental Study on Characterization of Micromachined Thermal Gas Inertial Sensors
Sensors 2010, 10(9), 8304-8315; doi:10.3390/s100908304
Received: 29 June 2010 / Revised: 26 July 2010 / Accepted: 1 September 2010 / Published: 2 September 2010
Cited by 7 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a
[...] Read more.
Micromachined thermal gas inertial sensors based on heat convection are novel devices that compared with conventional micromachined inertial sensors offer the advantages of simple structures, easy fabrication, high shock resistance and good reliability by virtue of using a gaseous medium instead of a mechanical proof mass as key moving and sensing elements. This paper presents an analytical modeling for a micromachined thermal gas gyroscope integrated with signal conditioning. A simplified spring-damping model is utilized to characterize the behavior of the sensor. The model relies on the use of the fluid mechanics and heat transfer fundamentals and is validated using experimental data obtained from a test-device and simulation. Furthermore, the nonideal issues of the sensor are addressed from both the theoretical and experimental points of view. The nonlinear behavior demonstrated in experimental measurements is analyzed based on the model. It is concluded that the sources of nonlinearity are mainly attributable to the variable stiffness of the sensor system and the structural asymmetry due to nonideal fabrication. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle FPGA-based Fused Smart Sensor for Real-Time Plant-Transpiration Dynamic Estimation
Sensors 2010, 10(9), 8316-8331; doi:10.3390/s100908316
Received: 21 July 2010 / Revised: 6 August 2010 / Accepted: 20 August 2010 / Published: 2 September 2010
Cited by 9 | PDF Full-text (593 KB) | HTML Full-text | XML Full-text
Abstract
Plant transpiration is considered one of the most important physiological functions because it constitutes the plants evolving adaptation to exchange moisture with a dry atmosphere which can dehydrate or eventually kill the plant. Due to the importance of transpiration, accurate measurement methods are
[...] Read more.
Plant transpiration is considered one of the most important physiological functions because it constitutes the plants evolving adaptation to exchange moisture with a dry atmosphere which can dehydrate or eventually kill the plant. Due to the importance of transpiration, accurate measurement methods are required; therefore, a smart sensor that fuses five primary sensors is proposed which can measure air temperature, leaf temperature, air relative humidity, plant out relative humidity and ambient light. A field programmable gate array based unit is used to perform signal processing algorithms as average decimation and infinite impulse response filters to the primary sensor readings in order to reduce the signal noise and improve its quality. Once the primary sensor readings are filtered, transpiration dynamics such as: transpiration, stomatal conductance, leaf-air-temperature-difference and vapor pressure deficit are calculated in real time by the smart sensor. This permits the user to observe different primary and calculated measurements at the same time and the relationship between these which is very useful in precision agriculture in the detection of abnormal conditions. Finally, transpiration related stress conditions can be detected in real time because of the use of online processing and embedded communications capabilities. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
Figures

Open AccessArticle Sturdy Positioning with High Sensitivity GPS Sensors Under Adverse Conditions
Sensors 2010, 10(9), 8332-8347; doi:10.3390/s100908332
Received: 8 July 2010 / Revised: 20 August 2010 / Accepted: 20 August 2010 / Published: 3 September 2010
Cited by 9 | PDF Full-text (556 KB) | HTML Full-text | XML Full-text
Abstract
High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously deemed unsuitable for satellite signal reception. Under adverse conditions the signals become attenuated and reflected. High sensitivity receivers achieve signal reception by using a large number of
[...] Read more.
High sensitivity GPS receivers have extended the use of GNSS navigation to environments which were previously deemed unsuitable for satellite signal reception. Under adverse conditions the signals become attenuated and reflected. High sensitivity receivers achieve signal reception by using a large number of correlators and an extended integration time. Processing the observation data in dynamic and rapidly changing conditions requires a careful and consistent treatment. Code-based autonomous solutions can cause major errors in the estimated position, due primarily to multipath effects. A custom procedure of autonomous GPS positioning has been developed, boosting the positioning performance through appropriate processing of code and Doppler observations. Besides the common positioning procedures, robust estimation methods have been used to minimise the effects of gross observation errors. In normal conditions, differential GNSS yields good results, however, under adverse conditions, it fails to improve significantly the receiver’s position. Therefore, a so-called conditional DGPS has been developed which determines the position differentially by using data from the strong signals only. These custom-developed procedures have been tested in different conditions in static and kinematic cases and the results have been compared to those processed by the receiver. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Minimum Expected Delay-Based Routing Protocol (MEDR) for Delay Tolerant Mobile Sensor Networks
Sensors 2010, 10(9), 8348-8362; doi:10.3390/s100908348
Received: 20 July 2010 / Revised: 10 August 2010 / Accepted: 20 August 2010 / Published: 3 September 2010
Cited by 10 | PDF Full-text (543 KB) | HTML Full-text | XML Full-text
Abstract
It is a challenging work to develop efficient routing protocols for Delay Tolerant Mobile Sensor Networks (DTMSNs), which have several unique characteristics such as sensor mobility, intermittent connectivity, energy limit, and delay tolerability. In this paper, we propose a new routing protocol called
[...] Read more.
It is a challenging work to develop efficient routing protocols for Delay Tolerant Mobile Sensor Networks (DTMSNs), which have several unique characteristics such as sensor mobility, intermittent connectivity, energy limit, and delay tolerability. In this paper, we propose a new routing protocol called Minimum Expected Delay-based Routing (MEDR) tailored for DTMSNs. MEDR achieves a good routing performance by finding and using the connected paths formed dynamically by mobile sensors. In MEDR, each sensor maintains two important parameters: Minimum Expected Delay (MED) and its expiration time. According to MED, messages will be delivered to the sensor that has at least a connected path with their hosting nodes, and has the shortest expected delay to communication directly with the sink node. Because of the changing network topology, the path is fragile and volatile, so we use the expiration time of MED to indicate the valid time of the path, and avoid wrong transmissions. Simulation results show that the proposed MEDR achieves a higher message delivery ratio with lower transmission overhead and data delivery delay than other DTMSN routing approaches. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle Color Regeneration from Reflective Color Sensor Using an Artificial Intelligent Technique
Sensors 2010, 10(9), 8363-8374; doi:10.3390/s100908363
Received: 20 July 2010 / Revised: 10 August 2010 / Accepted: 20 August 2010 / Published: 3 September 2010
Cited by 13 | PDF Full-text (508 KB) | HTML Full-text | XML Full-text
Abstract
A low-cost optical sensor based on reflective color sensing is presented. Artificial neural network models are used to improve the color regeneration from the sensor signals. Analog voltages of the sensor are successfully converted to RGB colors. The artificial intelligent models presented in
[...] Read more.
A low-cost optical sensor based on reflective color sensing is presented. Artificial neural network models are used to improve the color regeneration from the sensor signals. Analog voltages of the sensor are successfully converted to RGB colors. The artificial intelligent models presented in this work enable color regeneration from analog outputs of the color sensor. Besides, inverse modeling supported by an intelligent technique enables the sensor probe for use of a colorimetric sensor that relates color changes to analog voltages. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Figures

Open AccessArticle Data Collection Framework for Energy Efficient Privacy Preservation in Wireless Sensor Networks Having Many-to-Many Structures
Sensors 2010, 10(9), 8375-8397; doi:10.3390/s100908375
Received: 21 July 2010 / Revised: 3 August 2010 / Accepted: 3 August 2010 / Published: 8 September 2010
PDF Full-text (367 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks (WSNs) generally have a many-to-one structure so that event information flows from sensors to a unique sink. In recent WSN applications, many-to-many structures evolved due to the need for conveying collected event information to multiple sinks. Privacy preserved data collection
[...] Read more.
Wireless sensor networks (WSNs) generally have a many-to-one structure so that event information flows from sensors to a unique sink. In recent WSN applications, many-to-many structures evolved due to the need for conveying collected event information to multiple sinks. Privacy preserved data collection models in the literature do not solve the problems of WSN applications in which network has multiple un-trusted sinks with different level of privacy requirements. This study proposes a data collection framework bases on k-anonymity for preventing record disclosure of collected event information in WSNs. Proposed method takes the anonymity requirements of multiple sinks into consideration by providing different levels of privacy for each destination sink. Attributes, which may identify an event owner, are generalized or encrypted in order to meet the different anonymity requirements of sinks at the same anonymized output. If the same output is formed, it can be multicasted to all sinks. The other trivial solution is to produce different anonymized outputs for each sink and send them to related sinks. Multicasting is an energy efficient data sending alternative for some sensor nodes. Since minimization of energy consumption is an important design criteria for WSNs, multicasting the same event information to multiple sinks reduces the energy consumption of overall network. Full article
Open AccessArticle A Novel Electrochemical Sensor for Probing Doxepin Created on a Glassy Carbon Electrode Modified with Poly(4-Amino- benzoic Acid)/Multi-Walled Carbon Nanotubes Composite Film
Sensors 2010, 10(9), 8398-8410; doi:10.3390/s100908398
Received: 7 July 2010 / Revised: 31 July 2010 / Accepted: 7 September 2010 / Published: 8 September 2010
Cited by 5 | PDF Full-text (622 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid)/multi-walled carbon nanotubes composite film [poly(4-ABA)/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that
[...] Read more.
A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid)/multi-walled carbon nanotubes composite film [poly(4-ABA)/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA)/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 ´ 10−9 to 1.0 ´ 10−6 M, and the detection limit obtained was 1.0 × 10−10 M. The poly(4-ABA)/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay. Full article
Figures

Open AccessArticle Combined Simulation of a Micro Permanent Magnetic Linear Contactless Displacement Sensor
Sensors 2010, 10(9), 8424-8436; doi:10.3390/s100908424
Received: 11 June 2010 / Revised: 17 August 2010 / Accepted: 6 September 2010 / Published: 9 September 2010
Cited by 3 | PDF Full-text (459 KB) | HTML Full-text | XML Full-text
Abstract
The permanent magnetic linear contactless displacement (PLCD) sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be
[...] Read more.
The permanent magnetic linear contactless displacement (PLCD) sensor is a new type of displacement sensor operating on the magnetic inductive principle. It has many excellent properties and has already been used for many applications. In this article a Micro-PLCD sensor which can be used for microelectromechanical system (MEMS) measurements is designed and simulated with the CST EM STUDIO® software, including building a virtual model, magnetostatic calculations, low frequency calculations, steady current calculations and thermal calculations. The influence of some important parameters such as air gap dimension, working frequency, coil current and eddy currents etc. is studied in depth. Full article
Figures

Open AccessArticle A High-Sensitivity Hydraulic Load Cell for Small Kitchen Appliances
Sensors 2010, 10(9), 8452-8465; doi:10.3390/s100908452
Received: 13 July 2010 / Revised: 18 August 2010 / Accepted: 6 September 2010 / Published: 9 September 2010
Cited by 2 | PDF Full-text (949 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present a hydraulic load cell made from hydroformed metallic bellows. The load cell was designed for a small kitchen appliance with the weighing function integrated into the composite control and protection of the appliance. It is a simple, low-cost
[...] Read more.
In this paper we present a hydraulic load cell made from hydroformed metallic bellows. The load cell was designed for a small kitchen appliance with the weighing function integrated into the composite control and protection of the appliance. It is a simple, low-cost solution with small dimensions and represents an alternative to the existing hydraulic load cells in industrial use. A good non-linearity and a small hysteresis were achieved. The influence of temperature leads to an error of 7.5%, which can be compensated for by software to meet the requirements of the target application. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy
Sensors 2010, 10(9), 8466-8477; doi:10.3390/s100908466
Received: 10 August 2010 / Revised: 30 August 2010 / Accepted: 8 September 2010 / Published: 9 September 2010
Cited by 9 | PDF Full-text (474 KB) | HTML Full-text | XML Full-text
Abstract
Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system
[...] Read more.
Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sample gas that promote the radiationless de-excitation of the oxygen molecules. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Adaptive Control of a Vibratory Angle Measuring Gyroscope
Sensors 2010, 10(9), 8478-8490; doi:10.3390/s100908478
Received: 11 August 2010 / Revised: 20 August 2010 / Accepted: 3 September 2010 / Published: 9 September 2010
Cited by 10 | PDF Full-text (1088 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an adaptive control algorithm for realizing a vibratory angle measuring gyroscope so that rotation angle can be directly measured without integration of angular rate, thus eliminating the accumulation of numerical integration errors. The proposed control algorithm uses a trajectory following
[...] Read more.
This paper presents an adaptive control algorithm for realizing a vibratory angle measuring gyroscope so that rotation angle can be directly measured without integration of angular rate, thus eliminating the accumulation of numerical integration errors. The proposed control algorithm uses a trajectory following approach and the reference trajectory is generated by an ideal angle measuring gyroscope driven by the estimate of angular rate and the auxiliary sinusoidal input so that the persistent excitation condition is satisfied. The developed control algorithm can compensate for all types of fabrication imperfections such as coupled damping and stiffness, and mismatched stiffness and un-equal damping term in an on-line fashion. The simulation results show the feasibility and effectiveness of the developed control algorithm that is capable of directly measuring rotation angle without the integration of angular rate. Full article
(This article belongs to the Special Issue Adaptive Sensing)
Open AccessArticle Accurate Permittivity Measurements for Microwave Imaging via Ultra-Wideband Removal of Spurious Reflectors
Sensors 2010, 10(9), 8491-8503; doi:10.3390/s100908491
Received: 5 August 2010 / Revised: 31 August 2010 / Accepted: 1 September 2010 / Published: 10 September 2010
Cited by 2 | PDF Full-text (876 KB) | HTML Full-text | XML Full-text
Abstract
The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to
[...] Read more.
The use of microwave imaging is becoming more prevalent for detection of interior hidden defects in manufactured and packaged materials. In applications for detection of hidden moisture, microwave tomography can be used to image the material and then perform an inverse calculation to derive an estimate of the variability of the hidden material, such internal moisture, thereby alerting personnel to damaging levels of the hidden moisture before material degradation occurs. One impediment to this type of imaging occurs with nearby objects create strong reflections that create destructive and constructive interference, at the receiver, as the material is conveyed past the imaging antenna array. In an effort to remove the influence of the reflectors, such as metal bale ties, research was conducted to develop an algorithm for removal of the influence of the local proximity reflectors from the microwave images. This research effort produced a technique, based upon the use of ultra-wideband signals, for the removal of spurious reflections created by local proximity reflectors. This improvement enables accurate microwave measurements of moisture in such products as cotton bales, as well as other physical properties such as density or material composition. The proposed algorithm was shown to reduce errors by a 4:1 ratio and is an enabling technology for imaging applications in the presence of metal bale ties. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Sensor Networks in the Low Lands
Sensors 2010, 10(9), 8504-8525; doi:10.3390/s100908504
Received: 21 July 2010 / Revised: 15 August 2010 / Accepted: 30 August 2010 / Published: 10 September 2010
Cited by 5 | PDF Full-text (3217 KB) | HTML Full-text | XML Full-text
Abstract
This paper provides an overview of scientific and industrial developments of the last decade in the area of sensor networks in The Netherlands (Low Lands). The goal is to highlight areas in which the Netherlands has made most contributions and is currently a
[...] Read more.
This paper provides an overview of scientific and industrial developments of the last decade in the area of sensor networks in The Netherlands (Low Lands). The goal is to highlight areas in which the Netherlands has made most contributions and is currently a dominant player in the field of sensor networks. On the one hand, motivations, addressed topics, and initiatives taken in this period are presented, while on the other hand, special emphasis is given to identifying current and future trends and formulating a vision for the coming five to ten years. The presented overview and trend analysis clearly show that Dutch research and industrial efforts, in line with recent worldwide developments in the field of sensor technology, present a clear shift from sensor node platforms, operating systems, communication, networking, and data management aspects of the sensor networks to reasoning/cognition, control, and actuation. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in The Netherlands)
Figures

Open AccessArticle FLP/FRT Recombination from Yeast: Application of a Two Gene Cassette Scheme as an Inducible System in Plants
Sensors 2010, 10(9), 8526-8535; doi:10.3390/s100908526
Received: 17 July 2010 / Revised: 23 August 2010 / Accepted: 6 September 2010 / Published: 13 September 2010
Cited by 8 | PDF Full-text (303 KB) | HTML Full-text | XML Full-text
Abstract
Phytosensors are plants that are genetically engineered for sensing and reporting the presence of a specific contaminant, including agriculturally important biological agents. Phytosensors are constructed by transforming plants to contain specific biotic- or abiotic-inducible promoters fused to a reporter gene. When such transgenic
[...] Read more.
Phytosensors are plants that are genetically engineered for sensing and reporting the presence of a specific contaminant, including agriculturally important biological agents. Phytosensors are constructed by transforming plants to contain specific biotic- or abiotic-inducible promoters fused to a reporter gene. When such transgenic plants encounter the target biotic or abiotic agent, the specific inducible promoter is triggered and subsequently drives the expression of the reporter gene, which produces a signal for detection. However, several systems lack robustness, rapid induction and promoter strength. Here, we tested the FLP/FRT recombination system in a construct containing a two gene cassette organization and examined its potential in transgenic Arabidopsis and tobacco plants using a b-glucuronidase (GUS) reporter. In this model system, a heat-shock inducible promoter was employed to control the expression of the FLP recombinase gene. Upon heat induction and subsequent active FLP-mediated excision event, the GUS gene was placed in close proximity to the 35S promoter resulting in an active GUS reporter expression. Our results demonstrate that the two gene cassette scheme of inducible FLP/FRT recombination system is functional in tobacco and Arabidopsis, providing additional insights into its possible application in phytosensing such as creating strong readout capabilities. Full article
(This article belongs to the Section Biosensors)
Figures

Open AccessArticle Recovery of Agricultural Odors and Odorous Compounds from Polyvinyl Fluoride Film Bags
Sensors 2010, 10(9), 8536-8552; doi:10.3390/s100908536
Received: 7 July 2010 / Revised: 2 August 2010 / Accepted: 20 August 2010 / Published: 13 September 2010
Cited by 34 | PDF Full-text (320 KB) | HTML Full-text | XML Full-text
Abstract
Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human panelists
[...] Read more.
Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human panelists using dynamic triangular forced-choice olfactometry. The purpose of this research was to simultaneously quantify and compare recoveries of odor and odorous compounds from both commercial and homemade PVF sampling bags. A standard gas mixture consisting of p-cresol (40 µg m−3) and seven volatile fatty acids: acetic (2,311 µg m−3), propionic (15,800 µg m−3), isobutyric (1,686 µg m−3), butyric (1,049 µg m−3), isovaleric (1,236 µg m−3), valeric (643 µg m−3), and hexanoic (2,158 µg m−3) was placed in the PVF bags at times of 1 h, 1 d, 2 d, 3 d, and 7 d prior to compound and odor concentration analyses. Compound concentrations were quantified using sorbent tubes and gas chromatography/mass spectrometry. Odor concentration, intensity, and hedonic tone were measured using a panel of trained human subjects. Compound recoveries ranged from 2 to 40% after 1 h and 0 to 14% after 7 d. Between 1 h and 7 d, odor concentrations increased by 45% in commercial bags, and decreased by 39% in homemade bags. Minimal changes were observed in intensity and hedonic tone over the same time period. These results suggest that PVF bags can bias individual compound concentrations and odor as measured by dynamic triangular forced-choice olfactometry. Full article
(This article belongs to the Special Issue Direct and Indirect Sensing of Odor and VOCs and Their Control)
Figures

Open AccessArticle A Rigid Image Registration Based on the Nonsubsampled Contourlet Transform and Genetic Algorithms
Sensors 2010, 10(9), 8553-8571; doi:10.3390/s100908553
Received: 15 June 2010 / Revised: 5 September 2010 / Accepted: 8 September 2010 / Published: 14 September 2010
Cited by 4 | PDF Full-text (739 KB) | HTML Full-text | XML Full-text
Abstract
Image registration is a fundamental task used in image processing to match two or more images taken at different times, from different sensors or from different viewpoints. The objective is to find in a huge search space of geometric transformations, an acceptable
[...] Read more.
Image registration is a fundamental task used in image processing to match two or more images taken at different times, from different sensors or from different viewpoints. The objective is to find in a huge search space of geometric transformations, an acceptable accurate solution in a reasonable time to provide better registered images. Exhaustive search is computationally expensive and the computational cost increases exponentially with the number of transformation parameters and the size of the data set. In this work, we present an efficient image registration algorithm that uses genetic algorithms within a multi-resolution framework based on the Non-Subsampled Contourlet Transform (NSCT). An adaptable genetic algorithm for registration is adopted in order to minimize the search space. This approach is used within a hybrid scheme applying the two techniques fitness sharing and elitism. Two NSCT based methods are proposed for registration. A comparative study is established between these methods and a wavelet based one. Because the NSCT is a shift-invariant multidirectional transform, the second method is adopted for its search speeding up property. Simulation results clearly show that both proposed techniques are really promising methods for image registration compared to the wavelet approach, while the second technique has led to the best performance results of all. Moreover, to demonstrate the effectiveness of these methods, these registration techniques have been successfully applied to register SPOT, IKONOS and Synthetic Aperture Radar (SAR) images. The algorithm has been shown to work perfectly well for multi-temporal satellite images as well, even in the presence of noise. Full article
(This article belongs to the Special Issue Image Sensors)
Open AccessArticle Identification of Granite Varieties from Colour Spectrum Data
Sensors 2010, 10(9), 8572-8584; doi:10.3390/s100908572
Received: 30 July 2010 / Revised: 27 August 2010 / Accepted: 8 September 2010 / Published: 14 September 2010
Cited by 4 | PDF Full-text (345 KB) | HTML Full-text | XML Full-text
Abstract
The granite processing sector of the northwest of Spain handles many varieties of granite with specific technical and aesthetic properties that command different prices in the natural stone market. Hence, correct granite identification and classification from the outset of processing to the end-product
[...] Read more.
The granite processing sector of the northwest of Spain handles many varieties of granite with specific technical and aesthetic properties that command different prices in the natural stone market. Hence, correct granite identification and classification from the outset of processing to the end-product stage optimizes the management and control of stocks of granite slabs and tiles and facilitates the operation of traceability systems. We describe a methodology for automatically identifying granite varieties by processing spectral information captured by a spectrophotometer at various stages of processing using functional machine learning techniques. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessArticle Java Simulations of Embedded Control Systems
Sensors 2010, 10(9), 8585-8603; doi:10.3390/s100908585
Received: 1 July 2010 / Revised: 26 August 2010 / Accepted: 26 August 2010 / Published: 15 September 2010
Cited by 2 | PDF Full-text (318 KB) | HTML Full-text | XML Full-text
Abstract
This paper introduces a new Open Source Java library suited for the simulation of embedded control systems. The library is based on the ideas and architecture of TrueTime, a toolbox of Matlab devoted to this topic, and allows Java programmers to simulate the
[...] Read more.
This paper introduces a new Open Source Java library suited for the simulation of embedded control systems. The library is based on the ideas and architecture of TrueTime, a toolbox of Matlab devoted to this topic, and allows Java programmers to simulate the performance of control processes which run in a real time environment. Such simulations can improve considerably the learning and design of multitasking real-time systems. Thechoice of Java increases considerably the usability of our library, because many educators program already in this language. But also because the library can be easily used by Easy Java Simulations (EJS), a popular modeling and authoring tool that is increasingly used in the field of Control Education. EJS allows instructors, students, and researchers with less programming capabilities to create advanced interactive simulations in Java. The paper describes the ideas, implementation, and sample use of the new library both for pure Java programmers and for EJS users. The JTT library and some examples are online available on http://lab.dia.uned.es/jtt. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle Raman Microspectroscopy of Individual Algal Cells: Sensing Unsaturation of Storage Lipids in vivo
Sensors 2010, 10(9), 8635-8651; doi:10.3390/s100908635
Received: 30 July 2010 / Revised: 25 August 2010 / Accepted: 14 September 2010 / Published: 17 September 2010
Cited by 63 | PDF Full-text (1384 KB) | HTML Full-text | XML Full-text
Abstract
Algae are becoming a strategic source of fuels, food, feedstocks, and biologically active compounds. This potential has stimulated the development of innovative analytical methods focused on these microorganisms. Algal lipids are among the most promising potential products for fuels as well as for
[...] Read more.
Algae are becoming a strategic source of fuels, food, feedstocks, and biologically active compounds. This potential has stimulated the development of innovative analytical methods focused on these microorganisms. Algal lipids are among the most promising potential products for fuels as well as for nutrition. The crucial parameter characterizing the algal lipids is the degree of unsaturation of the constituent fatty acids quantified by the iodine value. Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. The Raman spectra were collected from three selected algal species immobilized in an agarose gel. Prior to immobilization, the algae were cultivated in the stationary phase inducing an overproduction of lipids. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm−1 (cis C=C stretching mode) and 1,445 cm−1 (CH2 scissoring mode) as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids. These spectral features were first quantified for pure fatty acids of known iodine value. The resultant calibration curve was then used to calculate the effective iodine value of storage lipids in the living algal cells from their Raman spectra. We demonstrated that the iodine value differs significantly for the three studied algal species. Our spectroscopic estimations of the iodine value were validated using GC-MS measurements and an excellent agreement was found for the Trachydiscus minutus species. A good agreement was also found with the earlier published data on Botryococcus braunii. Thus, we propose that Raman microspectroscopy can become technique of choice in the rapidly expanding field of algal biotechnology. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Predicting the Detectability of Thin Gaseous Plumes in Hyperspectral Images Using Basis Vectors
Sensors 2010, 10(9), 8652-8662; doi:10.3390/s100908652
Received: 17 July 2010 / Revised: 13 August 2010 / Accepted: 19 August 2010 / Published: 17 September 2010
PDF Full-text (558 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a new method for predicting the detectability of thin gaseous plumes in hyperspectral images. The novelty of this method is the use of basis vectors for each of the spectral channels of a collection instrument to calculate noise-equivalent concentration-pathlengths instead
[...] Read more.
This paper describes a new method for predicting the detectability of thin gaseous plumes in hyperspectral images. The novelty of this method is the use of basis vectors for each of the spectral channels of a collection instrument to calculate noise-equivalent concentration-pathlengths instead of matching scene pixels to absorbance spectra of gases in a library. This method provides insight into regions of the spectrum where gas detection will be relatively easier or harder, as influenced by ground emissivity, temperature contrast, and the atmosphere. Our results show that data collection planning could be influenced by information about when potential plumes are likely to be over background segments that are most conducive to detection. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle Automated Construction of Node Software Using Attributes in a Ubiquitous Sensor Network Environment
Sensors 2010, 10(9), 8663-8682; doi:10.3390/s100908663
Received: 30 July 2010 / Revised: 6 September 2010 / Accepted: 10 September 2010 / Published: 17 September 2010
Cited by 7 | PDF Full-text (437 KB) | HTML Full-text | XML Full-text
Abstract
In sensor networks, nodes must often operate in a demanding environment facing restrictions such as restricted computing resources, unreliable wireless communication and power shortages. Such factors make the development of ubiquitous sensor network (USN) applications challenging. To help developers construct a large amount
[...] Read more.
In sensor networks, nodes must often operate in a demanding environment facing restrictions such as restricted computing resources, unreliable wireless communication and power shortages. Such factors make the development of ubiquitous sensor network (USN) applications challenging. To help developers construct a large amount of node software for sensor network applications easily and rapidly, this paper proposes an approach to the automated construction of node software for USN applications using attributes. In the proposed technique, application construction proceeds by first developing a model for the sensor network and then designing node software by setting the values of the predefined attributes. After that, the sensor network model and the design of node software are verified. The final source codes of the node software are automatically generated from the sensor network model. We illustrate the efficiency of the proposed technique by using a gas/light monitoring application through a case study of a Gas and Light Monitoring System based on the Nano-Qplus operating system. We evaluate the technique using a quantitative metric—the memory size of execution code for node software. Using the proposed approach, developers are able to easily construct sensor network applications and rapidly generate a large number of node softwares at a time in a ubiquitous sensor network environment. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessArticle Broadcast Authentication for Wireless Sensor Networks Using Nested Hashing and the Chinese Remainder Theorem
Sensors 2010, 10(9), 8683-8695; doi:10.3390/s100908683
Received: 23 July 2010 / Revised: 23 August 2010 / Accepted: 6 September 2010 / Published: 17 September 2010
Cited by 11 | PDF Full-text (173 KB) | HTML Full-text | XML Full-text
Abstract
Secure broadcasting is an essential feature for critical operations in wireless sensor network (WSNs). However, due to the limited resources of sensor networks, verifying the authenticity for broadcasted messages is a very difficult issue. μTESLA is a broadcast authentication protocol, which uses network-wide
[...] Read more.
Secure broadcasting is an essential feature for critical operations in wireless sensor network (WSNs). However, due to the limited resources of sensor networks, verifying the authenticity for broadcasted messages is a very difficult issue. μTESLA is a broadcast authentication protocol, which uses network-wide loose time synchronization with one-way hashed keys to provide the authenticity verification. However, it suffers from several flaws considering the delay tolerance, and the chain length restriction. In this paper, we propose a protocol which provides broadcast authentication for wireless sensor networks. This protocol uses a nested hash chain of two different hash functions and the Chinese Remainder Theorem (CRT). The two different nested hash functions are employed for the seed updating and the key generation. Each sensor node is challenged independently with a common broadcasting message using the CRT. Our algorithm provides forward and non-restricted key generation, and in addition, no time synchronization is required. Furthermore, receivers can instantly authenticate packets in real time. Moreover, the comprehensive analysis shows that this scheme is efficient and practical, and can achieve better performance than the μTESLA system. Full article
Open AccessArticle Inverse Problem in Nondestructive Testing Using Arrayed Eddy Current Sensors
Sensors 2010, 10(9), 8696-8704; doi:10.3390/s100908696
Received: 3 August 2010 / Revised: 30 August 2010 / Accepted: 15 September 2010 / Published: 20 September 2010
Cited by 6 | PDF Full-text (324 KB) | HTML Full-text | XML Full-text
Abstract
A fast crack profile reconstitution model in nondestructive testing is developed using an arrayed eddy current sensor. The inverse problem is based on an iterative solving of the direct problem using genetic algorithms. In the direct problem, assuming a current excitation, the incident
[...] Read more.
A fast crack profile reconstitution model in nondestructive testing is developed using an arrayed eddy current sensor. The inverse problem is based on an iterative solving of the direct problem using genetic algorithms. In the direct problem, assuming a current excitation, the incident field produced by all the coils of the arrayed sensor is obtained by the translation and superposition of the 2D axisymmetric finite element results obtained for one coil; the impedance variation of each coil, due to the crack, is obtained by the reciprocity principle involving the dyadic Green’s function. For the inverse problem, the surface of the crack is subdivided into rectangular cells, and the objective function is expressed only in terms of the depth of each cell. The evaluation of the dyadic Green’s function matrix is made independently of the iterative procedure, making the inversion very fast. Full article
Open AccessArticle Assessment of Human Ambulatory Speed by Measuring Near-Body Air Flow
Sensors 2010, 10(9), 8705-8718; doi:10.3390/s100908705
Received: 1 July 2010 / Revised: 2 September 2010 / Accepted: 17 September 2010 / Published: 20 September 2010
Cited by 4 | PDF Full-text (378 KB) | HTML Full-text | XML Full-text
Abstract
Accurate measurements of physical activity are important for the diagnosis of the exacerbation of chronic diseases. Accelerometers have been widely employed in clinical research for measuring activity intensity and investigating the association between physical activity and adverse health conditions. However, the ability of
[...] Read more.
Accurate measurements of physical activity are important for the diagnosis of the exacerbation of chronic diseases. Accelerometers have been widely employed in clinical research for measuring activity intensity and investigating the association between physical activity and adverse health conditions. However, the ability of accelerometers in assessing physical activity intensity such as walking speed has been constrained by the inter-individual variability in sensor output and by the necessity of developing unobtrusive low-power monitoring systems. This paper will present a study aimed at investigating the accuracy of a wearable measuring system of near-body air flow to determine ambulatory speed in the field. Full article
Open AccessArticle A Signal Normalization Technique for Illumination-Based Synchronization of 1,000-fps Real-Time Vision Sensors in Dynamic Scenes
Sensors 2010, 10(9), 8719-8739; doi:10.3390/s100908719
Received: 9 August 2010 / Revised: 9 September 2010 / Accepted: 10 September 2010 / Published: 20 September 2010
Cited by 3 | PDF Full-text (10768 KB) | HTML Full-text | XML Full-text
Abstract
To acquire images of dynamic scenes from multiple points of view simultaneously, the acquisition time of vision sensors should be synchronized. In this paper, an illumination-based synchronization derived from the phase-locked loop (PLL) mechanism based on the signal normalization method is proposed and evaluated. To eliminate the
[...] Read more.
To acquire images of dynamic scenes from multiple points of view simultaneously, the acquisition time of vision sensors should be synchronized. In this paper, an illumination-based synchronization derived from the phase-locked loop (PLL) mechanism based on the signal normalization method is proposed and evaluated. To eliminate the system dependency due to the amplitude fluctuation of the reference illumination, which may be caused by the moving objects or relative positional distance change between the light source and the observed objects, the fluctuant amplitude of the reference signal is normalized framely by the estimated maximum amplitude between the reference signal and its quadrature counterpart to generate a stable synchronization in highly dynamic scenes. Both simulated results and real world experimental results demonstrated successful synchronization result that 1,000-Hz frame rate vision sensors can be successfully synchronized to a LED illumination or its reflected light with satisfactory stability and only 28-μs jitters. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Design and Analysis of MEMS Based PVDF Ultrasonic Transducers for Vascular Imaging
Sensors 2010, 10(9), 8740-8750; doi:10.3390/s100908740
Received: 29 July 2010 / Revised: 9 September 2010 / Accepted: 13 September 2010 / Published: 21 September 2010
Cited by 7 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
Polyvinilidene fluoride (PVDF) single-element transducers for high-frequency (> 30 MHz) ultrasound imaging applications have been developed using MEMS (Micro-electro-Mechanical Systems) compatible techniques. Performance of these transducers has been investigated by analyzing the sources and effects of on-chip parasitic capacitances on the insertion-loss of
[...] Read more.
Polyvinilidene fluoride (PVDF) single-element transducers for high-frequency (> 30 MHz) ultrasound imaging applications have been developed using MEMS (Micro-electro-Mechanical Systems) compatible techniques. Performance of these transducers has been investigated by analyzing the sources and effects of on-chip parasitic capacitances on the insertion-loss of the transducers. Modeling and experimental studies showed that on-chip parasitic capacitances degraded the performance of the transducers and an improved method of fabrication was suggested and new devices were built. New devices developed with minimal parasitic effects were shown to improve the performance significantly. A 1-mm aperture PVDF device developed with minimal parasitic effects has resulted in a reduction of insertion loss of 21 dB compared with devices fabricated using a previous method. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Characteristics of Metal Enhanced Evanescent-Wave Microcavities
Sensors 2010, 10(9), 8751-8760; doi:10.3390/s100908751
Received: 27 July 2010 / Revised: 9 September 2010 / Accepted: 10 September 2010 / Published: 21 September 2010
Cited by 3 | PDF Full-text (473 KB) | HTML Full-text | XML Full-text
Abstract
This article presents the concept of storing optical energy using a metallic air gap microcavity. Evanescent waves are stored in the air gap of a dielectric/metal/air gap/metal planar microcavity. For an air gap with a micron scale distance between the two metals, incident
[...] Read more.
This article presents the concept of storing optical energy using a metallic air gap microcavity. Evanescent waves are stored in the air gap of a dielectric/metal/air gap/metal planar microcavity. For an air gap with a micron scale distance between the two metals, incident light excites the optical interface modes on the two metal-air interfaces simultaneously, being accompanied by enhanced evanescent fields. Numerical simulations show that the reflected light depends remarkably upon distributions of the enhanced electric fields in the air-gap at the optical mode excitations. The metallic microcavities have a Q value on the order of 102, as determined from calculations. Experimentally, a small mechanical variation of the air-gap distance exhibited a change of reflectivity. Full article
(This article belongs to the Special Issue Optical Resonant Microsensors)
Open AccessArticle Load-Adaptive Practical Multi-Channel Communications in Wireless Sensor Networks
Sensors 2010, 10(9), 8761-8781; doi:10.3390/s100908761
Received: 19 August 2010 / Revised: 14 September 2010 / Accepted: 15 September 2010 / Published: 21 September 2010
Cited by 1 | PDF Full-text (523 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs). In this paper, we present
[...] Read more.
In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs). In this paper, we present a multi-channel communications system for WSNs that is referred to as load-adaptive practical multi-channel communications (LPMC). LPMC estimates the active load of a channel at the sink since it has a more comprehensive view of the network behavior, and dynamically adds or removes channels based on the estimated load. LPMC updates the routing path to balance the loads of the channels. The nodes in a path use the same channel; therefore, they do not need to switch channels to receive or forward packets. LPMC has been evaluated through extensive simulations, and the results demonstrate that it can effectively increase the delivery ratio, network throughput, and channel utilization, and that it can decrease the end-to-end delay and energy consumption. Full article
Figures

Review

Jump to: Research

Open AccessReview Recent Trends in Monitoring of European Water Framework Directive Priority Substances Using Micro-Sensors: A 2007–2009 Review
Sensors 2010, 10(9), 7947-7978; doi:10.3390/s100907947
Received: 12 June 2010 / Revised: 21 July 2010 / Accepted: 9 August 2010 / Published: 26 August 2010
Cited by 17 | PDF Full-text (255 KB) | HTML Full-text | XML Full-text
Abstract
This review discusses from a critical perspective the development of new sensors for the measurement of priority pollutants targeted in the E.U. Water Framework Directive. Significant advances are reported in the paper and their advantages and limitations are also discussed. Future perspectives in
[...] Read more.
This review discusses from a critical perspective the development of new sensors for the measurement of priority pollutants targeted in the E.U. Water Framework Directive. Significant advances are reported in the paper and their advantages and limitations are also discussed. Future perspectives in this area are also pointed out in the conclusions. This review covers publications appeared since December 2006 (the publication date of the Swift report). Among priority substances, sensors for monitoring the four WFD metals represent 81% of published papers. None of analyzed publications present a micro-sensor totally validated in laboratory, ready for tests under real conditions in the field. The researches are mainly focused on the sensing part of the micro-sensors. Nevertheless, the main factor limiting micro-sensor applications in the environment is the ruggedness of the receptor towards environmental conditions. This point constitutes the first technological obstacle to be overcome for any long-term field tests. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessReview Sensors and Clinical Mastitis—The Quest for the Perfect Alert
Sensors 2010, 10(9), 7991-8009; doi:10.3390/s100907991
Received: 13 July 2010 / Revised: 9 August 2010 / Accepted: 20 August 2010 / Published: 27 August 2010
Cited by 39 | PDF Full-text (140 KB) | HTML Full-text | XML Full-text
Abstract
When cows on dairy farms are milked with an automatic milking system or in high capacity milking parlors, clinical mastitis (CM) cannot be adequately detected without sensors. The objective of this paper is to describe the performance demands of sensor systems to detect
[...] Read more.
When cows on dairy farms are milked with an automatic milking system or in high capacity milking parlors, clinical mastitis (CM) cannot be adequately detected without sensors. The objective of this paper is to describe the performance demands of sensor systems to detect CM and evaluats the current performance of these sensor systems. Several detection models based on different sensors were studied in the past. When evaluating these models, three factors are important: performance (in terms of sensitivity and specificity), the time window and the similarity of the study data with real farm data. A CM detection system should offer at least a sensitivity of 80% and a specificity of 99%. The time window should not be longer than 48 hours and study circumstances should be as similar to practical farm circumstances as possible. The study design should comprise more than one farm for data collection. Since 1992, 16 peer-reviewed papers have been published with a description and evaluation of CM detection models. There is a large variation in the use of sensors and algorithms. All this makes these results not very comparable. There is a also large difference in performance between the detection models and also a large variation in time windows used and little similarity between study data. Therefore, it is difficult to compare the overall performance of the different CM detection models. The sensitivity and specificity found in the different studies could, for a large part, be explained in differences in the used time window. None of the described studies satisfied the demands for CM detection models. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in The Netherlands)
Open AccessReview The Coverage Problem in Video-Based Wireless Sensor Networks: A Survey
Sensors 2010, 10(9), 8215-8247; doi:10.3390/s100908215
Received: 10 July 2010 / Revised: 20 July 2010 / Accepted: 15 August 2010 / Published: 2 September 2010
Cited by 56 | PDF Full-text (632 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks typically consist of a great number of tiny low-cost electronic devices with limited sensing and computing capabilities which cooperatively communicate to collect some kind of information from an area of interest. When wireless nodes of such networks are equipped with
[...] Read more.
Wireless sensor networks typically consist of a great number of tiny low-cost electronic devices with limited sensing and computing capabilities which cooperatively communicate to collect some kind of information from an area of interest. When wireless nodes of such networks are equipped with a low-power camera, visual data can be retrieved, facilitating a new set of novel applications. The nature of video-based wireless sensor networks demands new algorithms and solutions, since traditional wireless sensor networks approaches are not feasible or even efficient for that specialized communication scenario. The coverage problem is a crucial issue of wireless sensor networks, requiring specific solutions when video-based sensors are employed. In this paper, it is surveyed the state of the art of this particular issue, regarding strategies, algorithms and general computational solutions. Open research areas are also discussed, envisaging promising investigation considering coverage in video-based wireless sensor networks. Full article
(This article belongs to the Section Chemical Sensors)
Figures

Open AccessReview Electrochemical Glucose Sensors—Developments Using Electrostatic Assembly and Carbon Nanotubes for Biosensor Construction
Sensors 2010, 10(9), 8248-8274; doi:10.3390/s100908248
Received: 5 July 2010 / Revised: 9 August 2010 / Accepted: 10 August 2010 / Published: 2 September 2010
Cited by 46 | PDF Full-text (321 KB) | HTML Full-text | XML Full-text
Abstract
In 1962, Clark and Lyons proposed incorporating the enzyme glucose oxidase in the construction of an electrochemical sensor for glucose in blood plasma. In their application, Clark and Lyons describe an electrode in which a membrane permeable to glucose traps a small volume
[...] Read more.
In 1962, Clark and Lyons proposed incorporating the enzyme glucose oxidase in the construction of an electrochemical sensor for glucose in blood plasma. In their application, Clark and Lyons describe an electrode in which a membrane permeable to glucose traps a small volume of solution containing the enzyme adjacent to a pH electrode, and the presence of glucose is detected by the change in the electrode potential that occurs when glucose reacts with the enzyme in this volume of solution. Although described nearly 50 years ago, this seminal development provides the general structure for constructing electrochemical glucose sensors that is still used today. Despite the maturity of the field, new developments that explore solutions to the fundamental limitations of electrochemical glucose sensors continue to emerge. Here we discuss two developments of the last 15 years; confining the enzyme and a redox mediator to a very thin molecular films at electrode surfaces by electrostatic assembly, and the use of electrodes modified by carbon nanotubes (CNTs) to leverage the electrocatalytic effect of the CNTs to reduce the oxidation overpotential of the electrode reaction or for the direct electron transport to the enzyme. Full article
(This article belongs to the Special Issue Glucose Sensors)
Open AccessReview Novel Ultra-Sensitive Detectors in the 10–50 μm Wavelength Range
Sensors 2010, 10(9), 8411-8423; doi:10.3390/s100908411
Received: 29 July 2010 / Revised: 13 August 2010 / Accepted: 31 August 2010 / Published: 8 September 2010
Cited by 11 | PDF Full-text (698 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We have developed novel single-photon detectors in the 10–50 μm wavelength region. The detectors are charge-sensitive infrared phototransistors (CSIPs) fabricated in GaAs/AlGaAs double quantum well (QW) structures, in which a photo-generated hole (+e) in the floating gate (upper QW) modulates the conductance of
[...] Read more.
We have developed novel single-photon detectors in the 10–50 μm wavelength region. The detectors are charge-sensitive infrared phototransistors (CSIPs) fabricated in GaAs/AlGaAs double quantum well (QW) structures, in which a photo-generated hole (+e) in the floating gate (upper QW) modulates the conductance of a capacitively-coupled channel located underneath (lower QW). The excellent noise equivalent power (NEP = 8.3 × 10−19 W/Hz1/2) and specific detectivity (D* = 8 × 1014 cm Hz1/2/W) are demonstrated for 15 micron detection up to 23 K, which are by a few orders of magnitude better than those of other state-of-the-art high-sensitivity detectors. The dynamic range exceeds 106 (~aW to pW) by repeatedly resetting the accumulated holes in the upper QW. Simple device structure makes the detectors feasible for array fabrication: Furthermore, monolithic integration with reading circuits will be possible. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Figures

Open AccessReview Automated Three-Dimensional Microbial Sensing and Recognition Using Digital Holography and Statistical Sampling
Sensors 2010, 10(9), 8437-8451; doi:10.3390/s100908437
Received: 18 June 2010 / Revised: 30 August 2010 / Accepted: 3 September 2010 / Published: 9 September 2010
Cited by 5 | PDF Full-text (852 KB) | HTML Full-text | XML Full-text
Abstract
We overview an approach to providing automated three-dimensional (3D) sensing and recognition of biological micro/nanoorganisms integrating Gabor digital holographic microscopy and statistical sampling methods. For 3D data acquisition of biological specimens, a coherent beam propagates through the specimen and its transversely and longitudinally
[...] Read more.
We overview an approach to providing automated three-dimensional (3D) sensing and recognition of biological micro/nanoorganisms integrating Gabor digital holographic microscopy and statistical sampling methods. For 3D data acquisition of biological specimens, a coherent beam propagates through the specimen and its transversely and longitudinally magnified diffraction pattern observed by the microscope objective is optically recorded with an image sensor array interfaced with a computer. 3D visualization of the biological specimen from the magnified diffraction pattern is accomplished by using the computational Fresnel propagation algorithm. For 3D recognition of the biological specimen, a watershed image segmentation algorithm is applied to automatically remove the unnecessary background parts in the reconstructed holographic image. Statistical estimation and inference algorithms are developed to the automatically segmented holographic image. Overviews of preliminary experimental results illustrate how the holographic image reconstructed from the Gabor digital hologram of biological specimen contains important information for microbial recognition. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessReview ZnO-Based Ultraviolet Photodetectors
Sensors 2010, 10(9), 8604-8634; doi:10.3390/s100908604
Received: 30 July 2010 / Revised: 25 August 2010 / Accepted: 10 September 2010 / Published: 17 September 2010
Cited by 173 | PDF Full-text (5743 KB) | HTML Full-text | XML Full-text
Abstract
Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one
[...] Read more.
Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Figures

Journal Contact

MDPI AG
Sensors Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
sensors@mdpi.com
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Sensors
Back to Top