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Sensors, Volume 11, Issue 12 (December 2011), Pages 11036-11920

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Research

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Open AccessArticle Earthworm (Eisenia andrei) Avoidance of Soils Treated with Cypermethrin
Sensors 2011, 11(12), 11056-11063; doi:10.3390/s111211056
Received: 11 October 2011 / Revised: 11 November 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 5 | PDF Full-text (181 KB) | HTML Full-text | XML Full-text
Abstract
The pyrethroid insecticide cypermethrin is used for agricultural and public health campaigns. Its residues may contaminate soils and the beneficial soil organisms, like the earthworms, that may ingest the contaminated soil particles. Due to its ecological relevance, earthworms Eisenia andrei/fetida have been used in different ecotoxicological tests. The avoidance of soils treated with cypermethrin by compost worms Eisenia andrei was studied here as a bioindicator of the influence of treatment dosage and the pesticide formulation in three different agricultural soils indicated by the Brazilian environmental authorities for ecotoxicological tests. This earthworms’ behavior was studied here as a first attempt to propose the test for regulation purposes. The two-compartment test systems, where the earthworms were placed for a two-day exposure period, contained samples of untreated soil alone or together with soil treated with technical grade or wettable powder formulation of cypermethrin. After 48 h, there was no mortality, but the avoidance was clear because all earthworms were found in the untreated section of each type of soil (p < 0.05). No differences were found by the Fisher’s exact test (p ≤ 1.000) for each soil and treatment, demonstrating that the different soil characteristics, the cypermethrin concentrations and formulation, as well as the smaller amounts of soil and earthworms did not influence the avoidance behavior of the earthworms to cypermethrin. The number and range of treatments used in this study do not allow a detailed recommendation of the conditions applied here, but to the best of our knowledge, this is the first reported attempt to identify the avoidance of pesticide treated tropical soils by earthworms. Full article
(This article belongs to the Special Issue Sensing of Organic Pollution in Soil, Air, Water and Food)
Open AccessArticle Serological Thymidine Kinase 1 is a Biomarker for Early Detection of Tumours—A Health Screening Study on 35,365 People, Using a Sensitive Chemiluminescent Dot Blot Assay
Sensors 2011, 11(12), 11064-11080; doi:10.3390/s111211064
Received: 30 September 2011 / Revised: 30 October 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 13 | PDF Full-text (240 KB) | HTML Full-text | XML Full-text
Abstract
Serological thymidine kinase 1 (STK1) is a reliable proliferation marker for prognosis, monitoring tumour therapy, and relapse. Here we investigated the use of STK1 in health screening for early detection of pre-malignant and malignant diseases. The investigation was based on 35,365 participants in four independent health screening studies in China between 2005–2011. All participants were clinically examined. The concentration of STK1 was determined by a sensitive chemiluminescent dot blot ECL assay. The ROCvalue of the STK1 assay was 0.96. At a cut-off STK1 value of 2.0 pM, the likelihood (+) value was 236.5, and the sensitivity and the specificity were 0.78 and 0.99, respectively. The relative number of city-dwelling people with elevated STK1 values (≥2.0 pM) was 0.8% (198/26,484), while the corresponding value for the group of oil-field workers was 5.8% (514/8,355). The latter group expressed significantly higher frequency of refractory anaemia, fatty liver, and obesity, compared to the city dwellers, but no cases of breast hyperplasia or prostate hyperplasia. Furthermore, people working in oil drilling/oil transportation showed higher STK1 values and higher frequency of pre-malignancies and benign diseases than people working in the oil-field administration. In the STK1 elevated group of the city-dwelling people, a statistically significantly higher number of people were found to have malignancies, pre-malignancies of all types, moderate/severe type of hyperplasia of breast or prostate, or refractory anaemia, or to be at high risk for hepatitis B, compared to people with normal STK1 values (< 2.0 pM). No malignancies were found in the normal STK1 group. In the elevated STK1 group 85.4% showed diseases linked to a higher risk for pre-/early cancerous progression, compared to 52.4% of those with normal STK1 values. Among participants with elevated STK1 values, 8.8% developed new malignancies or progress in their pre-malignancies within 5 to 72 months, compared to 0.2% among people with normal STK1 values. People who showed elevated STK1 values were at about three to five times higher risk to develop malignancies compared to a calculated risk based on a cancer incidence rate of 0.2–0.3%. We conclude that serological TK1 protein concentration is a reliable marker for risk assessment of pre/early cancerous progression. Full article
(This article belongs to the Special Issue Biomarkers and Nanosensors: New Approaches for Biology and Medicine)
Open AccessArticle Magnetic Field Measurements Based on Terfenol Coated Photonic Crystal Fibers
Sensors 2011, 11(12), 11103-11111; doi:10.3390/s111211103
Received: 25 October 2011 / Revised: 21 November 2011 / Accepted: 23 November 2011 / Published: 28 November 2011
Cited by 14 | PDF Full-text (384 KB) | HTML Full-text | XML Full-text
Abstract
A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the [...] Read more.
A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the HiBi fiber. Changes in the cavity length as well as the effective refractive index are induced by exposing the sensor head to magnetic fields. The magnetic field sensor has a sensitivity of 0.006 (nm/mT) over a range from 0 to 300 mT with a resolution about ±1 mT. A fiber Bragg grating magnetic field sensor is also fabricated and employed to characterize the response of Terfenol composite to the magnetic field. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
Open AccessArticle A Zinc Oxide Nanorod Ammonia Microsensor Integrated with a Readout Circuit on-a-Chip
Sensors 2011, 11(12), 11112-11121; doi:10.3390/s111211112
Received: 13 October 2011 / Revised: 22 November 2011 / Accepted: 23 November 2011 / Published: 28 November 2011
Cited by 13 | PDF Full-text (1054 KB) | HTML Full-text | XML Full-text
Abstract
A zinc oxide nanorod ammonia microsensor integrated with a readout circuit on-a-chip fabricated using the commercial 0.35 mm complementary metal oxide semiconductor (CMOS) process was investigated. The structure of the ammonia sensor is composed of a sensitive film and polysilicon electrodes. The [...] Read more.
A zinc oxide nanorod ammonia microsensor integrated with a readout circuit on-a-chip fabricated using the commercial 0.35 mm complementary metal oxide semiconductor (CMOS) process was investigated. The structure of the ammonia sensor is composed of a sensitive film and polysilicon electrodes. The ammonia sensor requires a post-process to etch the sacrificial layer, and to coat the sensitive film on the polysilicon electrodes. The sensitive film that is prepared by a hydrothermal method is made of zinc oxide. The sensor resistance changes when the sensitive film adsorbs or desorbs ammonia gas. The readout circuit is used to convert the sensor resistance into the voltage output. Experiments show that the ammonia sensor has a sensitivity of about 1.5 mV/ppm at room temperature. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2011)
Open AccessArticle A New MANET Wormhole Detection Algorithm Based on Traversal Time and Hop Count Analysis
Sensors 2011, 11(12), 11122-11140; doi:10.3390/s111211122
Received: 27 September 2011 / Revised: 21 November 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 4 | PDF Full-text (517 KB) | HTML Full-text | XML Full-text
Abstract
As demand increases for ubiquitous network facilities, infrastructure-less and self-configuring systems like Mobile Ad hoc Networks (MANET) are gaining popularity. MANET routing security however, is one of the most significant challenges to wide scale adoption, with wormhole attacks being an especially severe [...] Read more.
As demand increases for ubiquitous network facilities, infrastructure-less and self-configuring systems like Mobile Ad hoc Networks (MANET) are gaining popularity. MANET routing security however, is one of the most significant challenges to wide scale adoption, with wormhole attacks being an especially severe MANET routing threat. This is because wormholes are able to disrupt a major component of network traffic, while concomitantly being extremely difficult to detect. This paper introduces a new wormhole detection paradigm based upon Traversal Time and Hop Count Analysis (TTHCA), which in comparison to existing algorithms, consistently affords superior detection performance, allied with low false positive rates for all wormhole variants. Simulation results confirm that the TTHCA model exhibits robust wormhole route detection in various network scenarios, while incurring only a small network overhead. This feature makes TTHCA an attractive choice for MANET environments which generally comprise devices, such as wireless sensors, which possess a limited processing capability. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Gaussian Multiscale Aggregation Applied to Segmentation in Hand Biometrics
Sensors 2011, 11(12), 11141-11156; doi:10.3390/s111211141
Received: 14 October 2011 / Revised: 7 November 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 1 | PDF Full-text (4075 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an image segmentation algorithm based on Gaussian multiscale aggregation oriented to hand biometric applications. The method is able to isolate the hand from a wide variety of background textures such as carpets, fabric, glass, grass, soil or stones. The [...] Read more.
This paper presents an image segmentation algorithm based on Gaussian multiscale aggregation oriented to hand biometric applications. The method is able to isolate the hand from a wide variety of background textures such as carpets, fabric, glass, grass, soil or stones. The evaluation was carried out by using a publicly available synthetic database with 408,000 hand images in different backgrounds, comparing the performance in terms of accuracy and computational cost to two competitive segmentation methods existing in literature, namely Lossy Data Compression (LDC) and Normalized Cuts (NCuts). The results highlight that the proposed method outperforms current competitive segmentation methods with regard to computational cost, time performance, accuracy and memory usage. Full article
(This article belongs to the Special Issue Hand-Based Biometrics Sensors and Systems)
Open AccessArticle Design and Implementation of a Biomimetic Turtle Hydrofoil for an Autonomous Underwater Vehicle
Sensors 2011, 11(12), 11168-11187; doi:10.3390/s111211168
Received: 20 October 2011 / Revised: 16 November 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 2 | PDF Full-text (1923 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the design and implementation of a turtle hydrofoil for an Autonomous Underwater Vehicle (AUV). The final design of the AUV must have navigation performance like a turtle, which has also been the biomimetic inspiration for the design of the [...] Read more.
This paper presents the design and implementation of a turtle hydrofoil for an Autonomous Underwater Vehicle (AUV). The final design of the AUV must have navigation performance like a turtle, which has also been the biomimetic inspiration for the design of the hydrofoil and propulsion system. The hydrofoil design is based on a National Advisory Committee for Aeronautics (NACA) 0014 hydrodynamic profile. During the design stage, four different propulsion systems were compared in terms of propulsion path, compactness, sealing and required power. The final implementation is based on a ball-and-socket mechanism because it is very compact and provides three degrees of freedom (DoF) to the hydrofoil with very few restrictions on the propulsion path. The propulsion obtained with the final implementation of the hydrofoil has been empirically evaluated in a water channel comparing different motion strategies. The results obtained have confirmed that the proposed turtle hydrofoil controlled with a mechanism with three DoF generates can be used in the future implementation of the planned AUV. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Modeling the Behavior of an Underwater Acoustic Relative Positioning System Based on Complementary Set of Sequences
Sensors 2011, 11(12), 11188-11205; doi:10.3390/s111211188
Received: 17 October 2011 / Revised: 1 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 5 | PDF Full-text (631 KB) | HTML Full-text | XML Full-text
Abstract
The great variability usually found in underwater media makes modeling a challenging task, but helpful for better understanding or predicting the performance of future deployed systems. In this work, an underwater acoustic propagation model is presented. This model obtains the multipath structure [...] Read more.
The great variability usually found in underwater media makes modeling a challenging task, but helpful for better understanding or predicting the performance of future deployed systems. In this work, an underwater acoustic propagation model is presented. This model obtains the multipath structure by means of the ray tracing technique. Using this model, the behavior of a relative positioning system is presented. One of the main advantages of relative positioning systems is that only the distances between all the buoys are needed to obtain their positions. In order to obtain the distances, the propagation times of acoustic signals coded by Complementary Set of Sequences (CSS) are used. In this case, the arrival instants are obtained by means of correlation processes. The distances are then used to obtain the position of the buoys by means of the Multidimensional Scaling Technique (MDS). As an early example of an application using this relative positioning system, a tracking of the position of the buoys at different times is performed. With this tracking, the surface current of a particular region could be studied. The performance of the system is evaluated in terms of the distance from the real position to the estimated one. Full article
(This article belongs to the Special Issue Sensorial Systems Applied to Intelligent Spaces)
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Open AccessArticle Design, Fabrication and Levitation Experiments of a Micromachined Electrostatically Suspended Six-Axis Accelerometer
Sensors 2011, 11(12), 11206-11234; doi:10.3390/s111211206
Received: 22 October 2011 / Revised: 16 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 10 | PDF Full-text (1672 KB) | HTML Full-text | XML Full-text
Abstract
A micromachined electrostatically suspended six-axis accelerometer, with a square plate as proof mass housed by a top stator and bottom stator, is presented. The device structure and related techniques concerning its operating principles, such as calculation of capacitances and electrostatic forces/moments, detection [...] Read more.
A micromachined electrostatically suspended six-axis accelerometer, with a square plate as proof mass housed by a top stator and bottom stator, is presented. The device structure and related techniques concerning its operating principles, such as calculation of capacitances and electrostatic forces/moments, detection and levitation control of the proof mass, acceleration measurement, and structural parameters design, are described. Hybrid MEMS manufacturing techniques, including surface micromachining fabrication of thin film electrodes and interconnections, integration fabrication of thick nickel structures about 500 μm using UV-LIGA by successful removal of SU-8 photoresist mold, DRIE of silicon proof mass in thickness of 450 μm, microassembly and solder bonding, were employed to fabricate this prototype microdevice. A levitation experiment system for the fabricated microaccelerometer chip is introduced, and levitation results show that fast initial levitation within 10 ms and stable full suspension of the proof mass have been successfully demonstrated. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Design of Sensor Data Processing Steps in an Air Pollution Monitoring System
Sensors 2011, 11(12), 11235-11250; doi:10.3390/s111211235
Received: 27 September 2011 / Revised: 14 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 6 | PDF Full-text (2597 KB) | HTML Full-text | XML Full-text
Abstract
Environmental monitoring is required to understand the effects of various kinds of phenomena such as a flood, a typhoon, or a forest fire. To detect the environmental conditions in remote places, monitoring applications employ the sensor networks to detect conditions, context models [...] Read more.
Environmental monitoring is required to understand the effects of various kinds of phenomena such as a flood, a typhoon, or a forest fire. To detect the environmental conditions in remote places, monitoring applications employ the sensor networks to detect conditions, context models to understand phenomena, and computing technology to process the large volumes of data. In this paper, we present an air pollution monitoring system to provide alarm messages about potentially dangerous areas with sensor data analysis. We design the data analysis steps to understand the detected air pollution regions and levels. The analyzed data is used to track the pollution and to give an alarm. This implemented monitoring system is used to mitigate the damages caused by air pollution. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle The New Pelagic Operational Observatory of the Catalan Sea (OOCS) for the Multisensor Coordinated Measurement of Atmospheric and Oceanographic Conditions
Sensors 2011, 11(12), 11251-11272; doi:10.3390/s111211251
Received: 8 October 2011 / Revised: 7 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 5 | PDF Full-text (1854 KB) | HTML Full-text | XML Full-text
Abstract
The new pelagic Operational Observatory of the Catalan Sea (OOCS) for the coordinated multisensor measurement of atmospheric and oceanographic conditions has been recently installed (2009) in the Catalan Sea (41°39'N, 2°54'E; Western Mediterranean) and continuously operated (with minor maintenance gaps) until today. [...] Read more.
The new pelagic Operational Observatory of the Catalan Sea (OOCS) for the coordinated multisensor measurement of atmospheric and oceanographic conditions has been recently installed (2009) in the Catalan Sea (41°39'N, 2°54'E; Western Mediterranean) and continuously operated (with minor maintenance gaps) until today. This multiparametric platform is moored at 192 m depth, 9.3 km off Blanes harbour (Girona, Spain). It is composed of a buoy holding atmospheric sensors and a set of oceanographic sensors measuring the water conditions over the upper 100 m depth. The station is located close to the head of the Blanes submarine canyon where an important multispecies pelagic and demersal fishery gives the station ecological and economic relevance. The OOCS provides important records on atmospheric and oceanographic conditions, the latter through the measurement of hydrological and biogeochemical parameters, at depths with a time resolution never attained before for this area of the Mediterranean. Twenty four moored sensors and probes operating in a coordinated fashion provide important data on Essential Ocean Variables (EOVs; UNESCO) such as temperature, salinity, pressure, dissolved oxygen, chlorophyll fluorescence, and turbidity. In comparison with other pelagic observatories presently operating in other world areas, OOCS also measures photosynthetic available radiation (PAR) from above the sea surface and at different depths in the upper 50 m. Data are recorded each 30 min and transmitted in real-time to a ground station via GPRS. This time series is published and automatically updated at the frequency of data collection on the official OOCS website (http://www.ceab.csic.es/~oceans). Under development are embedded automated routines for the in situ data treatment and assimilation into numerical models, in order to provide a reliable local marine processing forecast. In this work, our goal is to detail the OOCS multisensor architecture in relation to the coordinated capability for the remote, continuous and prolonged monitoring of atmospheric and oceanographic conditions, including data communication and storage. Accordingly, time series of measurements for a number of biological parameters will be presented for the summer months of 2011. Marine hindcast outputs from the numerical models implemented for simulating the conditions over the study area are shown. The strong changes of atmospheric conditions recorded in the last years over the area have altered the marine conditions of living organisms, but the dimension of the impact remains unclear. The OOCS multisensor coordinated monitoring has been specifically designed to address this issue, thus contributing to better understand the present environmental fluctuations and to provide a sound basis for a more accurate marine forecast system. Full article
(This article belongs to the Special Issue Collaborative Sensors)
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Open AccessArticle Modeling and Analysis of an Energy-Efficient Mobility Management Scheme in IP-Based Wireless Networks
Sensors 2011, 11(12), 11273-11294; doi:10.3390/s111211273
Received: 11 October 2011 / Revised: 7 November 2011 / Accepted: 21 November 2011 / Published: 28 November 2011
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Abstract
An energy-efficient mobility management scheme in IP-based wireless networks is proposed to reduce the battery power consumption of mobile hosts (MHs). The proposed scheme manages seven MH states, including transmitting, receiving, attention/cell-connected, attention/paging area(PA)-connected, idle, off/attached, and detached states, to efficiently manage [...] Read more.
An energy-efficient mobility management scheme in IP-based wireless networks is proposed to reduce the battery power consumption of mobile hosts (MHs). The proposed scheme manages seven MH states, including transmitting, receiving, attention/cell-connected, attention/paging area(PA)-connected, idle, off/attached, and detached states, to efficiently manage battery power, radio resources, and network load. We derive the stationary probabilities and steady state probabilities of the seven MH states for the proposed scheme in IP-based wireless networks in compact form. The effects of various input parameters on MH steady state probabilities and power consumption are investigated in the proposed scheme compared to the conventional scheme. Network costs such as cell updates, PA updates, binding-lifetime-based registrations, and paging messages are analyzed in the proposed and conventional schemes. The optimal values of PA size and registration interval are derived to minimize the network cost of the proposed scheme. The combined network and power costs are investigated for the proposed and conventional schemes. The results provide guidelines to select the proper system parameters in IP-based wireless networks. Full article
(This article belongs to the Special Issue Selected Papers from FGIT 2010)
Open AccessArticle Protein Binding Detection Using On-Chip Silicon Gratings
Sensors 2011, 11(12), 11295-11304; doi:10.3390/s111211295
Received: 18 October 2011 / Revised: 15 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 4 | PDF Full-text (1053 KB) | HTML Full-text | XML Full-text
Abstract
We demonstrate a silicon gratings-based biosensor to detect functionalized protein binding on its surface. The designed silicon gratings have sensitivities up to 197 nm/RIU in detecting refractive index change and 1.61 nm per nanometer of thickness change of bio-material on the surface [...] Read more.
We demonstrate a silicon gratings-based biosensor to detect functionalized protein binding on its surface. The designed silicon gratings have sensitivities up to 197 nm/RIU in detecting refractive index change and 1.61 nm per nanometer of thickness change of bio-material on the surface of silicon gratings. Functionalizing proteins on gratings surface by eliminating unspecific binding makes this device more selective and efficient. Streptavidin at a concentration of 0.016 µmol/mL was functionalized on silicon substrate and biotin of 12 µmol/mL concentration was used as a target molecule in our detection experiments. Normal transmission measurements of gratings are made in air at different stages of immobilization, bare silicon grating, after attaching streptavidin and after trapping biotin. Total shifts in resonant peak wavelength of ~15 nm in normal transmission were observed after immobilizing biotin with ~7 nm of shift in resonant peak wavelength after functionalizing streptavidin to silicon substrate. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle On the Biomimetic Design of Agile-Robot Legs
Sensors 2011, 11(12), 11305-11334; doi:10.3390/s111211305
Received: 3 November 2011 / Revised: 24 November 2011 / Accepted: 24 November 2011 / Published: 28 November 2011
Cited by 8 | PDF Full-text (26810 KB) | HTML Full-text | XML Full-text
Abstract
The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for [...] Read more.
The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented. Full article
(This article belongs to the Special Issue Biomimetic Sensors, Actuators and Integrated Systems)
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Open AccessArticle Time-Resolved Fluorescence Immunoassay for C-Reactive Protein Using Colloidal Semiconducting Nanoparticles
Sensors 2011, 11(12), 11335-11342; doi:10.3390/s111211335
Received: 24 August 2011 / Revised: 18 October 2011 / Accepted: 14 November 2011 / Published: 28 November 2011
Cited by 5 | PDF Full-text (207 KB) | HTML Full-text | XML Full-text
Abstract
Besides the typical short-lived fluorescence with decay times in the nanosecond range, colloidal II/VI semiconductor nanoparticles dispersed in buffer also possess a long-lived fluorescence component with decay times in the microsecond range. Here, the signal intensity of the long-lived luminescence at microsecond [...] Read more.
Besides the typical short-lived fluorescence with decay times in the nanosecond range, colloidal II/VI semiconductor nanoparticles dispersed in buffer also possess a long-lived fluorescence component with decay times in the microsecond range. Here, the signal intensity of the long-lived luminescence at microsecond range is shown to increase 1,000-fold for CdTe nanoparticles in PBS buffer. This long-lived fluorescence can be conveniently employed for time-gated fluorescence detection, which allows for improved signal-to-noise ratio and thus the use of low concentrations of nanoparticles. The detection principle is demonstrated with a time-resolved fluorescence immunoassay for the detection of C-reactive protein (CRP) using CdSe-ZnS nanoparticles and green light excitation. Full article
(This article belongs to the Special Issue Sensing with Quantum Dots)
Open AccessArticle A Hierarchical Communication Architecture for Oceanic Surveillance Applications
Sensors 2011, 11(12), 11343-11356; doi:10.3390/s111211343
Received: 18 October 2011 / Revised: 18 November 2011 / Accepted: 27 November 2011 / Published: 30 November 2011
Cited by 5 | PDF Full-text (790 KB) | HTML Full-text | XML Full-text
Abstract
The interest in monitoring applications using underwater sensor networks has been growing in recent years. The severe communication restrictions imposed by underwater channels make that efficient monitoring be a challenging task. Though a lot of research has been conducted on underwater sensor [...] Read more.
The interest in monitoring applications using underwater sensor networks has been growing in recent years. The severe communication restrictions imposed by underwater channels make that efficient monitoring be a challenging task. Though a lot of research has been conducted on underwater sensor networks, there are only few concrete applications to a real-world case study. In this work, hence, we propose a general three tier architecture leveraging low cost wireless technologies for acoustic communications between underwater sensors and standard technologies, Zigbee and Wireless Fidelity (WiFi), for water surface communications. We have selected a suitable Medium Access Control (MAC) layer, after making a comparison with some common MAC protocols. Thus the performance of the overall system in terms of Signals Discarding Rate (SDR), signalling delay at the surface gateway as well as the percentage of true detection have been evaluated by simulation, pointing out good results which give evidence in applicability’s favour. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
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Open AccessArticle Finger Vein Recognition Using Local Line Binary Pattern
Sensors 2011, 11(12), 11357-11371; doi:10.3390/s111211357
Received: 1 November 2011 / Revised: 28 November 2011 / Accepted: 29 November 2011 / Published: 30 November 2011
Cited by 44 | PDF Full-text (6283 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a personal verification method using finger vein is presented. Finger vein can be considered more secured compared to other hands based biometric traits such as fingerprint and palm print because the features are inside the human body. In the [...] Read more.
In this paper, a personal verification method using finger vein is presented. Finger vein can be considered more secured compared to other hands based biometric traits such as fingerprint and palm print because the features are inside the human body. In the proposed method, a new texture descriptor called local line binary pattern (LLBP) is utilized as feature extraction technique. The neighbourhood shape in LLBP is a straight line, unlike in local binary pattern (LBP) which is a square shape. Experimental results show that the proposed method using LLBP has better performance than the previous methods using LBP and local derivative pattern (LDP). Full article
(This article belongs to the Special Issue Hand-Based Biometrics Sensors and Systems)
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Open AccessArticle Improving Social Odometry Robot Networks with Distributed Reputation Systems for Collaborative Purposes
Sensors 2011, 11(12), 11372-11389; doi:10.3390/s111211372
Received: 31 October 2011 / Revised: 21 November 2011 / Accepted: 22 November 2011 / Published: 30 November 2011
Cited by 2 | PDF Full-text (314 KB) | HTML Full-text | XML Full-text
Abstract
The improvement of odometry systems in collaborative robotics remains an important challenge for several applications. Social odometry is a social technique which confers the robots the possibility to learn from the others. This paper analyzes social odometry and proposes and follows a [...] Read more.
The improvement of odometry systems in collaborative robotics remains an important challenge for several applications. Social odometry is a social technique which confers the robots the possibility to learn from the others. This paper analyzes social odometry and proposes and follows a methodology to improve its behavior based on cooperative reputation systems. We also provide a reference implementation that allows us to compare the performance of the proposed solution in highly dynamic environments with the performance of standard social odometry techniques. Simulation results quantitatively show the benefits of this collaborative approach that allows us to achieve better performances than social odometry. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle Use of Earth’s Magnetic Field for Mitigating Gyroscope Errors Regardless of Magnetic Perturbation
Sensors 2011, 11(12), 11390-11414; doi:10.3390/s111211390
Received: 15 October 2011 / Revised: 21 November 2011 / Accepted: 22 November 2011 / Published: 30 November 2011
Cited by 33 | PDF Full-text (2329 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
Most portable systems like smart-phones are equipped with low cost consumer grade sensors, making them useful as Pedestrian Navigation Systems (PNS). Measurements of these sensors are severely contaminated by errors caused due to instrumentation and environmental issues rendering the unaided navigation solution [...] Read more.
Most portable systems like smart-phones are equipped with low cost consumer grade sensors, making them useful as Pedestrian Navigation Systems (PNS). Measurements of these sensors are severely contaminated by errors caused due to instrumentation and environmental issues rendering the unaided navigation solution with these sensors of limited use. The overall navigation error budget associated with pedestrian navigation can be categorized into position/displacement errors and attitude/orientation errors. Most of the research is conducted for tackling and reducing the displacement errors, which either utilize Pedestrian Dead Reckoning (PDR) or special constraints like Zero velocity UPdaTes (ZUPT) and Zero Angular Rate Updates (ZARU). This article targets the orientation/attitude errors encountered in pedestrian navigation and develops a novel sensor fusion technique to utilize the Earth’s magnetic field, even perturbed, for attitude and rate gyroscope error estimation in pedestrian navigation environments where it is assumed that Global Navigation Satellite System (GNSS) navigation is denied. As the Earth’s magnetic field undergoes severe degradations in pedestrian navigation environments, a novel Quasi-Static magnetic Field (QSF) based attitude and angular rate error estimation technique is developed to effectively use magnetic measurements in highly perturbed environments. The QSF scheme is then used for generating the desired measurements for the proposed Extended Kalman Filter (EKF) based attitude estimator. Results indicate that the QSF measurements are capable of effectively estimating attitude and gyroscope errors, reducing the overall navigation error budget by over 80% in urban canyon environment. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle On Mobility Management in Multi-Sink Sensor Networks for Geocasting of Queries
Sensors 2011, 11(12), 11415-11446; doi:10.3390/s111211415
Received: 1 November 2011 / Revised: 21 November 2011 / Accepted: 28 November 2011 / Published: 1 December 2011
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Abstract
In order to efficiently deal with location dependent messages in multi-sink wireless sensor networks (WSNs), it is key that the network informs sinks what geographical area is covered by which sink. The sinks are then able to efficiently route messages which are [...] Read more.
In order to efficiently deal with location dependent messages in multi-sink wireless sensor networks (WSNs), it is key that the network informs sinks what geographical area is covered by which sink. The sinks are then able to efficiently route messages which are only valid in particular regions of the deployment. In our previous work (see the 5th and 6th cited documents), we proposed a combined coverage area reporting and geographical routing protocol for location dependent messages, for example, queries that are injected by sinks. In this paper, we study the case where we have static sinks and mobile sensor nodes in the network. To provide up-to-date coverage areas to sinks, we focus on handling node mobility in the network. We discuss what is a better method for updating the routing structure (i.e., routing trees and coverage areas) to handle mobility efficiently: periodic global updates initiated from sinks or local updates triggered by mobile sensors. Simulation results show that local updating perform very well in terms of query delivery ratio. Local updating has a better scalability to increasing network size. It is also more energy efficient than ourpreviously proposed approach, where global updating in networks have medium mobility rate and speed. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle An Approach to Improve the Quality of Infrared Images of Vein-Patterns
Sensors 2011, 11(12), 11447-11463; doi:10.3390/s111211447
Received: 30 September 2011 / Revised: 23 November 2011 / Accepted: 29 November 2011 / Published: 1 December 2011
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Abstract
This study develops an approach to improve the quality of infrared (IR) images of vein-patterns, which usually have noise, low contrast, low brightness and small objects of interest, thus requiring preprocessing to improve their quality. The main characteristics of the proposed approach [...] Read more.
This study develops an approach to improve the quality of infrared (IR) images of vein-patterns, which usually have noise, low contrast, low brightness and small objects of interest, thus requiring preprocessing to improve their quality. The main characteristics of the proposed approach are that no prior knowledge about the IR image is necessary and no parameters must be preset. Two main goals are sought: impulse noise reduction and adaptive contrast enhancement technologies. In our study, a fast median-based filter (FMBF) is developed as a noise reduction method. It is based on an IR imaging mechanism to detect the noisy pixels and on a modified median-based filter to remove the noisy pixels in IR images. FMBF has the advantage of a low computation load. In addition, FMBF can retain reasonably good edges and texture information when the size of the filter window increases. The most important advantage is that the peak signal-to-noise ratio (PSNR) caused by FMBF is higher than the PSNR caused by the median filter. A hybrid cumulative histogram equalization (HCHE) is proposed for adaptive contrast enhancement. HCHE can automatically generate a hybrid cumulative histogram (HCH) based on two different pieces of information about the image histogram. HCHE can improve the enhancement effect on hot objects rather than background. The experimental results are addressed and demonstrate that the proposed approach is feasible for use as an effective and adaptive process for enhancing the quality of IR vein-pattern images. Full article
(This article belongs to the Special Issue Hand-Based Biometrics Sensors and Systems)
Open AccessArticle Ultrasonic Array for Obstacle Detection Based on CDMA with Kasami Codes
Sensors 2011, 11(12), 11464-11475; doi:10.3390/s111211464
Received: 20 October 2011 / Revised: 21 November 2011 / Accepted: 21 November 2011 / Published: 2 December 2011
Cited by 9 | PDF Full-text (529 KB) | HTML Full-text | XML Full-text
Abstract
This paper raises the design of an ultrasonic array for obstacle detection based on Phased Array (PA) techniques, which steers the acoustic beam through the environment by electronics rather than mechanical means. The transmission of every element in the array has been [...] Read more.
This paper raises the design of an ultrasonic array for obstacle detection based on Phased Array (PA) techniques, which steers the acoustic beam through the environment by electronics rather than mechanical means. The transmission of every element in the array has been encoded, according to Code Division for Multiple Access (CDMA), which allows multiple beams to be transmitted simultaneously. All these features together enable a parallel scanning system which does not only improve the image rate but also achieves longer inspection distances in comparison with conventional PA techniques. Full article
(This article belongs to the Special Issue Sensorial Systems Applied to Intelligent Spaces)
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Open AccessArticle Development of a 3D Parallel Mechanism Robot Arm with Three Vertical-Axial Pneumatic Actuators Combined with a Stereo Vision System
Sensors 2011, 11(12), 11476-11494; doi:10.3390/s111211476
Received: 15 October 2011 / Revised: 28 November 2011 / Accepted: 29 November 2011 / Published: 5 December 2011
Cited by 5 | PDF Full-text (1496 KB) | HTML Full-text | XML Full-text
Abstract
This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D [...] Read more.
This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot’s end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle Design of a Lightweight, Cost Effective Thimble-Like Sensor for Haptic Applications Based on Contact Force Sensors
Sensors 2011, 11(12), 11495-11509; doi:10.3390/s111211495
Received: 25 October 2011 / Revised: 1 December 2011 / Accepted: 5 December 2011 / Published: 6 December 2011
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Abstract
This paper describes the design and calibration of a thimble that measures the forces applied by a user during manipulation of virtual and real objects. Haptic devices benefit from force measurement capabilities at their end-point. However, the heavy weight and cost of [...] Read more.
This paper describes the design and calibration of a thimble that measures the forces applied by a user during manipulation of virtual and real objects. Haptic devices benefit from force measurement capabilities at their end-point. However, the heavy weight and cost of force sensors prevent their widespread incorporation in these applications. The design of a lightweight, user-adaptable, and cost-effective thimble with four contact force sensors is described in this paper. The sensors are calibrated before being placed in the thimble to provide normal and tangential forces. Normal forces are exerted directly by the fingertip and thus can be properly measured. Tangential forces are estimated by sensors strategically placed in the thimble sides. Two applications are provided in order to facilitate an evaluation of sensorized thimble performance. These applications focus on: (i) force signal edge detection, which determines task segmentation of virtual object manipulation, and (ii) the development of complex object manipulation models, wherein the mechanical features of a real object are obtained and these features are then reproduced for training by means of virtual object manipulation. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene
Sensors 2011, 11(12), 11510-11515; doi:10.3390/s111211510
Received: 17 November 2011 / Revised: 1 December 2011 / Accepted: 5 December 2011 / Published: 8 December 2011
Cited by 2 | PDF Full-text (748 KB) | HTML Full-text | XML Full-text
Abstract
Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. [...] Read more.
Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering. Full article
(This article belongs to the Special Issue Sensing of Organic Pollution in Soil, Air, Water and Food)
Open AccessArticle An Integrated Testbed for Cooperative Perception with Heterogeneous Mobile and Static Sensors
Sensors 2011, 11(12), 11516-11543; doi:10.3390/s111211516
Received: 12 November 2011 / Revised: 28 November 2011 / Accepted: 28 November 2011 / Published: 9 December 2011
Cited by 22 | PDF Full-text (3482 KB) | HTML Full-text | XML Full-text
Abstract
Cooperation among devices with different sensing, computing and communication capabilities provides interesting possibilities in a growing number of problems and applications including domotics (domestic robotics), environmental monitoring or intelligent cities, among others. Despite the increasing interest in academic and industrial communities, experimental [...] Read more.
Cooperation among devices with different sensing, computing and communication capabilities provides interesting possibilities in a growing number of problems and applications including domotics (domestic robotics), environmental monitoring or intelligent cities, among others. Despite the increasing interest in academic and industrial communities, experimental tools for evaluation and comparison of cooperative algorithms for such heterogeneous technologies are still very scarce. This paper presents a remote testbed with mobile robots and Wireless Sensor Networks (WSN) equipped with a set of low-cost off-the-shelf sensors, commonly used in cooperative perception research and applications, that present high degree of heterogeneity in their technology, sensed magnitudes, features, output bandwidth, interfaces and power consumption, among others. Its open and modular architecture allows tight integration and interoperability between mobile robots and WSN through a bidirectional protocol that enables full interaction. Moreover, the integration of standard tools and interfaces increases usability, allowing an easy extension to new hardware and software components and the reuse of code. Different levels of decentralization are considered, supporting from totally distributed to centralized approaches. Developed for the EU-funded Cooperating Objects Network of Excellence (CONET) and currently available at the School of Engineering of Seville (Spain), the testbed provides full remote control through the Internet. Numerous experiments have been performed, some of which are described in the paper. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle Heterogeneous Collaborative Sensor Network for Electrical Management of an Automated House with PV Energy
Sensors 2011, 11(12), 11544-11559; doi:10.3390/s111211544
Received: 20 October 2011 / Revised: 28 November 2011 / Accepted: 5 December 2011 / Published: 9 December 2011
Cited by 6 | PDF Full-text (2909 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we present a heterogeneous collaborative sensor network for electrical management in the residential sector. Improving demand-side management is very important in distributed energy generation applications. Sensing and control are the foundations of the “Smart Grid” which is the future [...] Read more.
In this paper we present a heterogeneous collaborative sensor network for electrical management in the residential sector. Improving demand-side management is very important in distributed energy generation applications. Sensing and control are the foundations of the “Smart Grid” which is the future of large-scale energy management. The system presented in this paper has been developed on a self-sufficient solar house called “MagicBox” equipped with grid connection, PV generation, lead-acid batteries, controllable appliances and smart metering. Therefore, there is a large number of energy variables to be monitored that allow us to precisely manage the energy performance of the house by means of collaborative sensors. The experimental results, performed on a real house, demonstrate the feasibility of the proposed collaborative system to reduce the consumption of electrical power and to increase energy efficiency. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle ATLAS: A Traffic Load Aware Sensor MAC Design for Collaborative Body Area Sensor Networks
Sensors 2011, 11(12), 11560-11580; doi:10.3390/s111211560
Received: 20 October 2011 / Revised: 20 November 2011 / Accepted: 9 December 2011 / Published: 12 December 2011
Cited by 11 | PDF Full-text (458 KB) | HTML Full-text | XML Full-text
Abstract
In collaborative body sensor networks, namely wireless body area networks(WBANs), each of the physical sensor applications is used to collaboratively monitor thehealth status of the human body. The applications of WBANs comprise diverse and dynamictraffic loads such as very low-rate periodic monitoring [...] Read more.
In collaborative body sensor networks, namely wireless body area networks(WBANs), each of the physical sensor applications is used to collaboratively monitor thehealth status of the human body. The applications of WBANs comprise diverse and dynamictraffic loads such as very low-rate periodic monitoring (i.e., observation) data and high-ratetraffic including event-triggered bursts. Therefore, in designing a medium access control(MAC) protocol for WBANs, energy conservation should be the primary concern duringlow-traffic periods, whereas a balance between satisfying high-throughput demand andefficient energy usage is necessary during high-traffic times. In this paper, we design atraffic load-aware innovative MAC solution for WBANs, called ATLAS. The design exploitsthe superframe structure of the IEEE 802.15.4 standard, and it adaptively uses the contentionaccess period (CAP), contention free period (CFP) and inactive period (IP) of the superframebased on estimated traffic load, by applying a dynamic “wh” (whenever which is required)approach. Unlike earlier work, the proposed MAC design includes load estimation fornetwork load-status awareness and a multi-hop communication pattern in order to preventenergy loss associated with long range transmission. Finally, ATLAS is evaluated throughextensive simulations in ns-2 and the results demonstrate the effectiveness of the protocol. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle Towards Smart Homes Using Low Level Sensory Data
Sensors 2011, 11(12), 11581-11604; doi:10.3390/s111211581
Received: 26 October 2011 / Revised: 28 November 2011 / Accepted: 7 December 2011 / Published: 12 December 2011
Cited by 11 | PDF Full-text (934 KB) | HTML Full-text | XML Full-text
Abstract
Ubiquitous Life Care (u-Life care) is receiving attention because it provides high quality and low cost care services. To provide spontaneous and robust healthcare services, knowledge of a patient’s real-time daily life activities is required. Context information with real-time daily life activities [...] Read more.
Ubiquitous Life Care (u-Life care) is receiving attention because it provides high quality and low cost care services. To provide spontaneous and robust healthcare services, knowledge of a patient’s real-time daily life activities is required. Context information with real-time daily life activities can help to provide better services and to improve healthcare delivery. The performance and accuracy of existing life care systems is not reliable, even with a limited number of services. This paper presents a Human Activity Recognition Engine (HARE) that monitors human health as well as activities using heterogeneous sensor technology and processes these activities intelligently on a Cloud platform for providing improved care at low cost. We focus on activity recognition using video-based, wearable sensor-based, and location-based activity recognition engines and then use intelligent processing to analyze the context of the activities performed. The experimental results of all the components showed good accuracy against existing techniques. The system is deployed on Cloud for Alzheimer’s disease patients (as a case study) with four activity recognition engines to identify low level activity from the raw data captured by sensors. These are then manipulated using ontology to infer higher level activities and make decisions about a patient’s activity using patient profile information and customized rules. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Dynamic Sensing Performance of a Point-Wise Fiber Bragg Grating Displacement Measurement System Integrated in an Active Structural Control System
Sensors 2011, 11(12), 11605-11628; doi:10.3390/s111211605
Received: 17 October 2011 / Revised: 28 November 2011 / Accepted: 3 December 2011 / Published: 13 December 2011
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Abstract
In this work, a fiber Bragg grating (FBG) sensing system which can measure the transient response of out-of-plane point-wise displacement responses is set up on a smart cantilever beam and the feasibility of its use as a feedback sensor in an active [...] Read more.
In this work, a fiber Bragg grating (FBG) sensing system which can measure the transient response of out-of-plane point-wise displacement responses is set up on a smart cantilever beam and the feasibility of its use as a feedback sensor in an active structural control system is studied experimentally. An FBG filter is employed in the proposed fiber sensing system to dynamically demodulate the responses obtained by the FBG displacement sensor with high sensitivity. For comparison, a laser Doppler vibrometer (LDV) is utilized simultaneously to verify displacement detection ability of the FBG sensing system. An optical full-field measurement technique called amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to provide full-field vibration mode shapes and resonant frequencies. To verify the dynamic demodulation performance of the FBG filter, a traditional FBG strain sensor calibrated with a strain gauge is first employed to measure the dynamic strain of impact-induced vibrations. Then, system identification of the smart cantilever beam is performed by FBG strain and displacement sensors. Finally, by employing a velocity feedback control algorithm, the feasibility of integrating the proposed FBG displacement sensing system in a collocated feedback system is investigated and excellent dynamic feedback performance is demonstrated. In conclusion, our experiments show that the FBG sensor is capable of performing dynamic displacement feedback and/or strain measurements with high sensitivity and resolution. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
Open AccessArticle Development of a Multisensor-Based Bio-Botanic Robot and Its Implementation Using a Self-Designed Embedded Board
Sensors 2011, 11(12), 11629-11648; doi:10.3390/s111211629
Received: 1 November 2011 / Revised: 25 November 2011 / Accepted: 5 December 2011 / Published: 13 December 2011
Cited by 1 | PDF Full-text (1583 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This paper presents the design concept of a bio-botanic robot which demonstrates its behavior based on plant growth. Besides, it can reflect the different phases of plant growth depending on the proportional amounts of light, temperature and water. The mechanism design is [...] Read more.
This paper presents the design concept of a bio-botanic robot which demonstrates its behavior based on plant growth. Besides, it can reflect the different phases of plant growth depending on the proportional amounts of light, temperature and water. The mechanism design is made up of a processed aluminum base, spring, polydimethylsiloxane (PDMS) and actuator to constitute the plant base and plant body. The control system consists of two micro-controllers and a self-designed embedded development board where the main controller transmits the values of the environmental sensing module within the embedded board to a sub-controller. The sub-controller determines the growth stage, growth height, and time and transmits its decision value to the main controller. Finally, based on the data transmitted by the sub-controller, the main controller controls the growth phase of the bio-botanic robot using a servo motor and leaf actuator. The research result not only helps children realize the variation of plant growth but also is entertainment-educational through its demonstration of the growth process of the bio-botanic robot in a short time. Full article
(This article belongs to the Special Issue Control Systems and Robotics in Bioengineering)
Open AccessArticle Pressure-Sensitive Paint: Effect of Substrate
Sensors 2011, 11(12), 11649-11663; doi:10.3390/s111211649
Received: 28 October 2011 / Revised: 6 December 2011 / Accepted: 7 December 2011 / Published: 14 December 2011
Cited by 13 | PDF Full-text (1598 KB) | HTML Full-text | XML Full-text
Abstract
There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One [...] Read more.
There are numerous ways in which pressure-sensitive paint can be applied to a surface. The choice of substrate and application method can greatly affect the results obtained. The current study examines the different methods of applying pressure-sensitive paint to a surface. One polymer-based and two porous substrates (anodized aluminum and thin-layer chromatography plates) are investigated and compared for luminescent output, pressure sensitivity, temperature sensitivity and photodegradation. Two luminophores [tris-Bathophenanthroline Ruthenium(II) Perchlorate and Platinum-tetrakis (pentafluorophenyl) Porphyrin] will also be compared in all three of the substrates. The results show the applicability of the different substrates and luminophores to different testing environments. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Amperometric Immunosensor Based on a Protein A/Deposited Gold Nanocrystals Modified Electrode for Carbofuran Detection
Sensors 2011, 11(12), 11679-11691; doi:10.3390/s111211679
Received: 10 November 2011 / Revised: 5 December 2011 / Accepted: 13 December 2011 / Published: 15 December 2011
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Abstract
In this paper, an amperometric immunosensor modified with protein A/deposited gold nanocrystals (DpAu) was developed for the ultrasensitive detection of carbofuran residues. First, DpAu were electrodeposited onto the Au electrode surface to absorb protein A (PA) and improve the electrode conductivity. Then [...] Read more.
In this paper, an amperometric immunosensor modified with protein A/deposited gold nanocrystals (DpAu) was developed for the ultrasensitive detection of carbofuran residues. First, DpAu were electrodeposited onto the Au electrode surface to absorb protein A (PA) and improve the electrode conductivity. Then PA was dropped onto the surface of DpAu film, used for binding antibody Fc fragments. Next, anti-carbofuran monoclonal antibody was immobilized on the PA modified electrode. Finally, bovine serum albumin (BSA) was employed to block the possible remaining active sites avoiding any nonspecific adsorption. The fabrication procedure of the immunosensor was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. With the excellent electroconductivity of DpAu and the PA’s oriented immobilization of antibodies, a highly efficient immuno-reaction and detection sensitivity could be achieved. The influences of the electrodeposition time of DpAu, pH of the detection solution and incubation time on the current response of the fabricated immunosensor were investigated. Under optimized conditions, the current response was proportional to the concentration of carbofuran which ranged from 1 to 100 ng/mL and 100 ng/mL to 100 μg/mL. The detection limit was 0.1924 ng/mL. The proposed carbofuran immnuosensor exhibited high specificity, reproducibility, stability and regeneration performance, which may open a new door for ultrasensitive detection of carbofuran residues in vegetables and fruits. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle A Cost Effective Block Framing Scheme for Underwater Communication
Sensors 2011, 11(12), 11717-11735; doi:10.3390/s111211717
Received: 16 November 2011 / Revised: 13 December 2011 / Accepted: 13 December 2011 / Published: 16 December 2011
Cited by 3 | PDF Full-text (638 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the Selective Multiple Acknowledgement (SMA) method, based on Multiple Acknowledgement (MA), is proposed to efficiently reduce the amount of data transmission by redesigning the transmission frame structure and taking into consideration underwater transmission characteristics. The method is suited to [...] Read more.
In this paper, the Selective Multiple Acknowledgement (SMA) method, based on Multiple Acknowledgement (MA), is proposed to efficiently reduce the amount of data transmission by redesigning the transmission frame structure and taking into consideration underwater transmission characteristics. The method is suited to integrated underwater system models, as the proposed method can handle the same amount of data in a much more compact frame structure without any appreciable loss of reliability. Herein, the performance of the proposed SMA method was analyzed and compared to those of the conventional Automatic Repeat-reQuest (ARQ), Block Acknowledgement (BA), block response, and MA methods. The efficiency of the underwater sensor network, which forms a large cluster and mostly contains uplink data, is expected to be improved by the proposed method. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
Open AccessArticle Low Cost Sensors Based on SPR in a Plastic Optical Fiber for Biosensor Implementation
Sensors 2011, 11(12), 11752-11760; doi:10.3390/s111211752
Received: 5 October 2011 / Revised: 8 December 2011 / Accepted: 15 December 2011 / Published: 16 December 2011
Cited by 38 | PDF Full-text (248 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports the fabrication and testing of two configurations of optical sensor systems based on Surface Plasmon Resonance (SPR) at the interface of a liquid sample and sandwiched structures realized starting from the exposed core of a Plastic Optical Fiber (POF). [...] Read more.
This paper reports the fabrication and testing of two configurations of optical sensor systems based on Surface Plasmon Resonance (SPR) at the interface of a liquid sample and sandwiched structures realized starting from the exposed core of a Plastic Optical Fiber (POF). The proposed geometries have proven to be suitable for measuring the refractive indexes of liquids whose refractive index falls around 1.35. Furthermore, the proposed sensing head, being low cost and relatively easy to realize, may be very attractive for biosensor implementation. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Force to Rebalance Control of HRG and Suppression of Its Errors on the Basis of FPGA
Sensors 2011, 11(12), 11761-11773; doi:10.3390/s111211761
Received: 8 November 2011 / Revised: 8 December 2011 / Accepted: 15 December 2011 / Published: 16 December 2011
Cited by 10 | PDF Full-text (780 KB) | HTML Full-text | XML Full-text
Abstract
A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode [...] Read more.
A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability. Full article
(This article belongs to the Special Issue Collaborative Sensors)
Open AccessArticle Surface Acoustic Wave (SAW) Vibration Sensors
Sensors 2011, 11(12), 11809-11832; doi:10.3390/s111211809
Received: 5 November 2011 / Revised: 5 December 2011 / Accepted: 15 December 2011 / Published: 19 December 2011
Cited by 8 | PDF Full-text (676 KB) | HTML Full-text | XML Full-text
Abstract
In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of [...] Read more.
In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit. Full article
(This article belongs to the Special Issue Emerging Acoustic Wave-Based Sensors)
Open AccessArticle A Query Result Merging Scheme for Providing Energy Efficiency in Underwater Sensor Networks
Sensors 2011, 11(12), 11833-11855; doi:10.3390/s111211833
Received: 26 November 2011 / Revised: 7 December 2011 / Accepted: 15 December 2011 / Published: 20 December 2011
Cited by 3 | PDF Full-text (1948 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Underwater sensor networks are emerging as a promising distributed data management system for various applications in underwater environments, despite their limited accessibility and restricted energy capacity. With the aid of recent developments in ubiquitous data computing, an increasing number of users are [...] Read more.
Underwater sensor networks are emerging as a promising distributed data management system for various applications in underwater environments, despite their limited accessibility and restricted energy capacity. With the aid of recent developments in ubiquitous data computing, an increasing number of users are expected to overcome low accessibility by applying queries to underwater sensor networks. However, when multiple users send queries to an underwater sensor network in a disorganized manner, it may incur lethal energy waste and problematic network traffic. The current query management mechanisms cannot effectively deal with this matter due to their limited applicability and unrealistic assumptions. In this paper, a novel query management scheme involving query result merging is proposed for underwater sensor networks. The mechanism is based on a relational database model and is adjusted to the practical restrictions affecting underwater communication environments. Network simulations will prove that the scheme becomes more efficient with a greater number of queries and a smaller period range. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
Open AccessArticle Characterization of a Low-Cost Optical Flow Sensor When Using an External Laser as a Direct Illumination Source
Sensors 2011, 11(12), 11856-11870; doi:10.3390/s111211856
Received: 21 November 2011 / Revised: 16 December 2011 / Accepted: 17 December 2011 / Published: 20 December 2011
Cited by 4 | PDF Full-text (871 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a low cost optical flow sensor is combined with an external laser device to measure surface displacements and mechanical oscillations. The measurement system is based on applying coherent light to a diffuser surface and using an optical flow sensor [...] Read more.
In this paper, a low cost optical flow sensor is combined with an external laser device to measure surface displacements and mechanical oscillations. The measurement system is based on applying coherent light to a diffuser surface and using an optical flow sensor to analyze the reflected and transferred light to estimate the displacement of the surface or the laser spot. This work is focused on the characterization of this measurement system, which can have the optical flow sensor placed at different angles and distances from the diffuser surface. The results have shown that the displacement of the diffuser surface is badly estimated when the optical mouse sensor is placed in front of the diffuser surface (angular orientation >150°) while the highest sensitivity is obtained when the sensor is located behind the diffuser surface and on the axis of the laser source (angular orientation 0°). In this case, the coefficient of determination of the measured displacement, R2, was very high (>0.99) with a relative error of less than 1.29%. Increasing the distance between the surface and the sensor also increased the sensitivity which increases linearly, R2 = 0.99. Finally, this measurement setup was proposed to measure very low frequency mechanical oscillations applied to the laser device, up to 0.01 Hz in this work. The results have shown that increasing the distance between the surface and the optical flow sensor also increases the sensitivity and the measurement range. Full article
(This article belongs to the Special Issue Ultra-Small Sensor Systems and Components)
Figures

Open AccessArticle Advances in SAW Gas Sensors Based on the Condensate-Adsorption Effect
Sensors 2011, 11(12), 11871-11884; doi:10.3390/s111211871
Received: 27 September 2011 / Revised: 24 November 2011 / Accepted: 19 December 2011 / Published: 20 December 2011
Cited by 11 | PDF Full-text (633 KB) | HTML Full-text | XML Full-text
Abstract
A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator [...] Read more.
A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Robust and Cooperative Image-Based Visual Servoing System Using a Redundant Architecture
Sensors 2011, 11(12), 11885-11900; doi:10.3390/s111211885
Received: 19 October 2011 / Revised: 13 December 2011 / Accepted: 15 December 2011 / Published: 20 December 2011
Cited by 4 | PDF Full-text (17483 KB) | HTML Full-text | XML Full-text
Abstract
The reliability and robustness of image-based visual servoing systems is still unsolved by the moment. In order to address this issue, a redundant and cooperative 2D visual servoing system based on the information provided by two cameras in eye-in-hand/eye-to-hand configurations is proposed. [...] Read more.
The reliability and robustness of image-based visual servoing systems is still unsolved by the moment. In order to address this issue, a redundant and cooperative 2D visual servoing system based on the information provided by two cameras in eye-in-hand/eye-to-hand configurations is proposed. Its control law has been defined to assure that the whole system is stable if each subsystem is stable and to allow avoiding typical problems of image-based visual servoing systems like task singularities, features extraction errors, disappearance of image features, local minima, etc. Experimental results with an industrial robot manipulator based on Schunk modular motors to demonstrate the stability, performance and robustness of the proposed system are presented. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Contamination of Runoff Water at Gdańsk Airport (Poland) by Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs)
Sensors 2011, 11(12), 11901-11920; doi:10.3390/s111211901
Received: 4 November 2011 / Revised: 29 November 2011 / Accepted: 9 December 2011 / Published: 20 December 2011
Cited by 4 | PDF Full-text (421 KB) | HTML Full-text | XML Full-text
Abstract
Airport runoff can contain high concentrations of various pollutants, in particular polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), the environmental levels of which have to be monitored. Airport runoff water samples, collected at the Gdańsk-Rębiechowo Airport from 2008 to 2009, [...] Read more.
Airport runoff can contain high concentrations of various pollutants, in particular polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), the environmental levels of which have to be monitored. Airport runoff water samples, collected at the Gdańsk-Rębiechowo Airport from 2008 to 2009, were analysed for PAHs and PCBs by gas chromatography. The aromatic fractions were separated by liquid-liquid extraction and analysed by GC/MS. Total PAH concentrations were 295–6,758 ng/L in 2008 and 180–1,924 ng/L in 2009, while total PCB levels in 2008 ranged from 0.14 to 0.44 µg/L and in 2009 from 0.06 to 0.23 µg/L. The PAH and PCB compositions in airport runoff waters were examined over a range of spatial and temporal scales to determine distributions, trends and possible sources. This pollution is mainly pyrolytic and related to anthropogenic activity. There were significant differences between the samples collected in the two seasons. An understanding of the magnitude of contamination due to airport runoff water is important for the effective management of airport infrastructure. Full article
(This article belongs to the Special Issue Sensing of Organic Pollution in Soil, Air, Water and Food)

Review

Jump to: Research

Open AccessReview Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals
Sensors 2011, 11(12), 11036-11055; doi:10.3390/s111211036
Received: 12 October 2011 / Revised: 21 November 2011 / Accepted: 22 November 2011 / Published: 28 November 2011
Cited by 57 | PDF Full-text (908 KB) | HTML Full-text | XML Full-text
Abstract
Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to [...] Read more.
Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands. Full article
(This article belongs to the Special Issue Sensing with Quantum Dots)
Open AccessReview Luminescence Sensors Applied to Water Analysis of Organic Pollutants—An Update
Sensors 2011, 11(12), 11081-11102; doi:10.3390/s111211081
Received: 27 September 2011 / Revised: 9 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 13 | PDF Full-text (409 KB) | HTML Full-text | XML Full-text
Abstract
The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted [...] Read more.
The development of chemical sensors for environmental analysis based on fluorescence, phosphorescence and chemiluminescence signals continues to be a dynamic topic within the sensor field. This review covers the fundamentals of this type of sensors, and an update on recent works devoted to quantifying organic pollutants in environmental waters, focusing on advances since about 2005. Among the wide variety of these contaminants, special attention has been paid polycyclic aromatic hydrocarbons, pesticides, explosives and emerging organic pollutants. The potential of coupling optical sensors with multivariate calibration methods in order to improve the selectivity is also discussed. Full article
(This article belongs to the Special Issue Sensing of Organic Pollution in Soil, Air, Water and Food)
Open AccessReview Earthworms and Soil Pollutants
Sensors 2011, 11(12), 11157-11167; doi:10.3390/s111211157
Received: 12 October 2011 / Revised: 1 November 2011 / Accepted: 18 November 2011 / Published: 28 November 2011
Cited by 6 | PDF Full-text (596 KB) | HTML Full-text | XML Full-text
Abstract
Although the toxicity of metal contaminated soils has been assessed with various bioassays, more information is needed about the biochemical responses, which may help to elucidate the mechanisms involved in metal toxicity. We previously reported that the earthworm, Eisenia fetida, accumulates [...] Read more.
Although the toxicity of metal contaminated soils has been assessed with various bioassays, more information is needed about the biochemical responses, which may help to elucidate the mechanisms involved in metal toxicity. We previously reported that the earthworm, Eisenia fetida, accumulates cadmium in its seminal vesicles. The bio-accumulative ability of earthworms is well known, and thus the earthworm could be a useful living organism for the bio-monitoring of soil pollution. In this short review, we describe recent studies concerning the relationship between earthworms and soil pollutants, and discuss the possibility of using the earthworm as a bio-monitoring organism for soil pollution. Full article
(This article belongs to the Special Issue Sensing of Toxic and Hazardous Metals in Various Environmental Media)
Open AccessReview CdTe and CdSe Quantum Dots Cytotoxicity: A Comparative Study on Microorganisms
Sensors 2011, 11(12), 11664-11678; doi:10.3390/s111211664
Received: 27 October 2011 / Revised: 26 November 2011 / Accepted: 9 December 2011 / Published: 15 December 2011
Cited by 17 | PDF Full-text (1649 KB) | HTML Full-text | XML Full-text
Abstract
Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe) or [...] Read more.
Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe) or cadmium selenium (CdSe) forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus. Full article
(This article belongs to the Special Issue Sensing with Quantum Dots)
Open AccessReview The Need and Potential of Biosensors to Detect Dioxins and Dioxin-Like Polychlorinated Biphenyls along the Milk, Eggs and Meat Food Chain
Sensors 2011, 11(12), 11692-11716; doi:10.3390/s111211692
Received: 17 October 2011 / Revised: 2 December 2011 / Accepted: 14 December 2011 / Published: 15 December 2011
Cited by 10 | PDF Full-text (258 KB) | HTML Full-text | XML Full-text
Abstract
Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are hazardous toxic, ubiquitous and persistent chemical compounds, which can enter the food chain and accumulate up to higher trophic levels. Their determination requires sophisticated methods, expensive facilities and instruments, well-trained personnel and expensive chemical reagents. [...] Read more.
Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are hazardous toxic, ubiquitous and persistent chemical compounds, which can enter the food chain and accumulate up to higher trophic levels. Their determination requires sophisticated methods, expensive facilities and instruments, well-trained personnel and expensive chemical reagents. Ideally, real-time monitoring using rapid detection methods should be applied to detect possible contamination along the food chain in order to prevent human exposure. Sensor technology may be promising in this respect. This review gives the state of the art for detecting possible contamination with dioxins and DL-PCBs along the food chain of animal-source foods. The main detection methods applied (i.e., high resolution gas-chromatography combined with high resolution mass-spectrometry (HRGC/HRMS) and the chemical activated luciferase gene expression method (CALUX bioassay)), each have their limitations. Biosensors for detecting dioxins and related compounds, although still under development, show potential to overcome these limitations. Immunosensors and biomimetic-based biosensors potentially offer increased selectivity and sensitivity for dioxin and DL-PCB detection, while whole cell-based biosensors present interpretable biological results. The main shortcoming of current biosensors, however, is their detection level: this may be insufficient as limits for dioxins and DL-PCBs for food and feedstuffs are in pg per gram level. In addition, these contaminants are normally present in fat, a difficult matrix for biosensor detection. Therefore, simple and efficient extraction and clean-up procedures are required which may enable biosensors to detect dioxins and DL-PCBs contamination along the food chain. Full article
(This article belongs to the Special Issue Sensing of Organic Pollution in Soil, Air, Water and Food)
Open AccessReview Semiconductor Quantum Dots for Biomedicial Applications
Sensors 2011, 11(12), 11736-11751; doi:10.3390/s111211736
Received: 2 November 2011 / Revised: 6 December 2011 / Accepted: 13 December 2011 / Published: 16 December 2011
Cited by 56 | PDF Full-text (457 KB) | HTML Full-text | XML Full-text
Abstract
Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed [...] Read more.
Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can be used as labels for the electrochemical detection of DNA or proteins. This article reviews the synthesis and toxicity of QDs and their optical and electrochemical bioanalytical applications. Especially the application of QDs in biomedicine such as delivering, cell targeting and imaging for cancer research, and in vivo photodynamic therapy (PDT) of cancer are briefly discussed. Full article
(This article belongs to the Special Issue Sensing with Quantum Dots)
Open AccessReview Electromagnetic Imaging Methods for Nondestructive Evaluation Applications
Sensors 2011, 11(12), 11774-11808; doi:10.3390/s111211774
Received: 29 August 2011 / Revised: 8 December 2011 / Accepted: 8 December 2011 / Published: 19 December 2011
Cited by 20 | PDF Full-text (6714 KB) | HTML Full-text | XML Full-text
Abstract
Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the [...] Read more.
Electromagnetic nondestructive tests are important and widely used within the field of nondestructive evaluation (NDE). The recent advances in sensing technology, hardware and software development dedicated to imaging and image processing, and material sciences have greatly expanded the application fields, sophisticated the systems design and made the potential of electromagnetic NDE imaging seemingly unlimited. This review provides a comprehensive summary of research works on electromagnetic imaging methods for NDE applications, followed by the summary and discussions on future directions. Full article
(This article belongs to the Section Physical Sensors)

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