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Sensors, Volume 10, Issue 10 (October 2010), Pages 8782-9540

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Open AccessArticle Improved Classification of Orthosiphon stamineus by Data Fusion of Electronic Nose and Tongue Sensors
Sensors 2010, 10(10), 8782-8796; doi:10.3390/s101008782
Received: 31 July 2010 / Revised: 22 August 2010 / Accepted: 2 September 2010 / Published: 28 September 2010
Cited by 18 | PDF Full-text (252 KB) | HTML Full-text | XML Full-text
Abstract
An improved classification of Orthosiphon stamineus using a data fusion technique is presented. Five different commercial sources along with freshly prepared samples were discriminated using an electronic nose (e-nose) and an electronic tongue (e-tongue). Samples from the different commercial brands were evaluated by
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An improved classification of Orthosiphon stamineus using a data fusion technique is presented. Five different commercial sources along with freshly prepared samples were discriminated using an electronic nose (e-nose) and an electronic tongue (e-tongue). Samples from the different commercial brands were evaluated by the e-tongue and then followed by the e-nose. Applying Principal Component Analysis (PCA) separately on the respective e-tongue and e-nose data, only five distinct groups were projected. However, by employing a low level data fusion technique, six distinct groupings were achieved. Hence, this technique can enhance the ability of PCA to analyze the complex samples of Orthosiphon stamineus. Linear Discriminant Analysis (LDA) was then used to further validate and classify the samples. It was found that the LDA performance was also improved when the responses from the e-nose and e-tongue were fused together. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Wireless Intelligent Sensors Management Application Protocol-WISMAP
Sensors 2010, 10(10), 8827-8849; doi:10.3390/s101008827
Received: 10 August 2010 / Revised: 13 September 2010 / Accepted: 15 September 2010 / Published: 28 September 2010
Cited by 9 | PDF Full-text (603 KB) | HTML Full-text | XML Full-text
Abstract
Although many recent studies have focused on the development of new applications for wireless sensor networks, less attention has been paid to knowledge-based sensor nodes. The objective of this work is the development in a real network of a new distributed system in
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Although many recent studies have focused on the development of new applications for wireless sensor networks, less attention has been paid to knowledge-based sensor nodes. The objective of this work is the development in a real network of a new distributed system in which every sensor node can execute a set of applications, such as fuzzy ruled-base systems, measures, and actions. The sensor software is based on a multi-agent structure that is composed of three components: management, application control, and communication agents; a service interface, which provides applications the abstraction of sensor hardware and other components; and an application layer protocol. The results show the effectiveness of the communication protocol and that the proposed system is suitable for a wide range of applications. As real world applications, this work presents an example of a fuzzy rule-based system and a noise pollution monitoring application that obtains a fuzzy noise indicator. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations
Sensors 2010, 10(10), 8850-8864; doi:10.3390/s101008850
Received: 8 July 2010 / Revised: 14 September 2010 / Accepted: 19 September 2010 / Published: 28 September 2010
Cited by 16 | PDF Full-text (356 KB) | HTML Full-text | XML Full-text
Abstract
Two manganese(III) porphyrins: manganese(III) tetraphenylporphyrin chloride and manganese(III)-tetrakis(3-hydroxyphenyl)porphyrin chloride were tested as ionophores for the construction of new diclofenac−selective electrodes. The electroactive material was incorporated either in PVC or a sol−gel matrix. The effect of different plasticizers and additives (anionic and cationic) on
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Two manganese(III) porphyrins: manganese(III) tetraphenylporphyrin chloride and manganese(III)-tetrakis(3-hydroxyphenyl)porphyrin chloride were tested as ionophores for the construction of new diclofenac−selective electrodes. The electroactive material was incorporated either in PVC or a sol−gel matrix. The effect of different plasticizers and additives (anionic and cationic) on the potentiometric response was studied. The best results were obtained for the PVC membrane plasticized with dioctylphtalate and having sodium tetraphenylborate as a lipophilic anionic additive incorporated. The sensor response was linear in the concentration range 3 × 10−6 – 1 × 10−2 M with a slope of −59.7 mV/dec diclofenac, a detection limit of 1.5 × 10−6 M and very good selectivity coefficients. It was used for the determination of diclofenac in pharmaceutical preparations, by direct potentiometry. The results were compared with those obtained by the HPLC reference method and a good agreement was found between the two methods. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Stereo Vision Tracking of Multiple Objects in Complex Indoor Environments
Sensors 2010, 10(10), 8865-8887; doi:10.3390/s101008865
Received: 31 August 2010 / Revised: 7 September 2010 / Accepted: 25 September 2010 / Published: 28 September 2010
Cited by 11 | PDF Full-text (1070 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This paper presents a novel system capable of solving the problem of tracking multiple targets in a crowded, complex and dynamic indoor environment, like those typical of mobile robot applications. The proposed solution is based on a stereo vision set in the acquisition
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This paper presents a novel system capable of solving the problem of tracking multiple targets in a crowded, complex and dynamic indoor environment, like those typical of mobile robot applications. The proposed solution is based on a stereo vision set in the acquisition step and a probabilistic algorithm in the obstacles position estimation process. The system obtains 3D position and speed information related to each object in the robot’s environment; then it achieves a classification between building elements (ceiling, walls, columns and so on) and the rest of items in robot surroundings. All objects in robot surroundings, both dynamic and static, are considered to be obstacles but the structure of the environment itself. A combination of a Bayesian algorithm and a deterministic clustering process is used in order to obtain a multimodal representation of speed and position of detected obstacles. Performance of the final system has been tested against state of the art proposals; test results validate the authors’ proposal. The designed algorithms and procedures provide a solution to those applications where similar multimodal data structures are found. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle A Bankruptcy Problem Approach to Load-shedding in Multiagent-based Microgrid Operation
Sensors 2010, 10(10), 8888-8898; doi:10.3390/s101008888
Received: 24 August 2010 / Revised: 19 September 2010 / Accepted: 26 September 2010 / Published: 28 September 2010
Cited by 17 | PDF Full-text (549 KB) | HTML Full-text | XML Full-text
Abstract
A microgrid is composed of distributed power generation systems (DGs), distributed energy storage devices (DSs), and loads. To maintain a specific frequency in the islanded mode as an important requirement,  the control of DGs’ output and charge action of DSs are used in
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A microgrid is composed of distributed power generation systems (DGs), distributed energy storage devices (DSs), and loads. To maintain a specific frequency in the islanded mode as an important requirement,  the control of DGs’ output and charge action of DSs are used in supply surplus conditions and load-shedding and discharge action of DSs are used in supply shortage conditions. Recently, multiagent systems for autonomous microgrid operation have been studied. Especially, load-shedding, which is intentional reduction of electricity use, is a critical problem in islanded microgrid operation based on the multiagent system. Therefore, effective schemes for load-shedding are required. Meanwhile, the bankruptcy problem deals with dividing short resources among multiple agents. In order to solve the bankruptcy problem, division rules, such as the constrained equal awards rule (CEA), the constrained equal losses rule (CEL), and the random arrival rule (RA), have been used. In this paper, we approach load-shedding as a bankruptcy problem. We compare load-shedding results by above-mentioned rules in islanded microgrid operation based on wireless sensor network (WSN) as the communication link for an agent’s interactions. Full article
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Open AccessArticle Multitemporal Observations of Sugarcane by TerraSAR-X Images
Sensors 2010, 10(10), 8899-8919; doi:10.3390/s101008899
Received: 21 July 2010 / Revised: 14 September 2010 / Accepted: 19 September 2010 / Published: 28 September 2010
Cited by 21 | PDF Full-text (527 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV)
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The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired less than two or three months after the cut. The radar signal decreases about 5dB for images acquired some days after the cut and 3 dB for data acquired two month after the cut (VV-37°). The difference in radar signal becomes negligible ( Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
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Open AccessArticle ZERO: Probabilistic Routing for Deploy and Forget Wireless Sensor Networks
Sensors 2010, 10(10), 8920-8937; doi:10.3390/s101008920
Received: 10 August 2010 / Revised: 18 September 2010 / Accepted: 20 September 2010 / Published: 29 September 2010
Cited by 6 | PDF Full-text (586 KB) | HTML Full-text | XML Full-text
Abstract
As Wireless Sensor Networks are being adopted by industry and agriculture for large-scale and unattended deployments, the need for reliable and energy-conservative protocols become critical. Physical and Link layer efforts for energy conservation are not mostly considered by routing protocols that put their
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As Wireless Sensor Networks are being adopted by industry and agriculture for large-scale and unattended deployments, the need for reliable and energy-conservative protocols become critical. Physical and Link layer efforts for energy conservation are not mostly considered by routing protocols that put their efforts on maintaining reliability and throughput. Gradient-based routing protocols route data through most reliable links aiming to ensure 99% packet delivery. However, they suffer from the so-called ”hot spot” problem. Most reliable routes waste their energy fast, thus partitioning the network and reducing the area monitored. To cope with this ”hot spot” problem we propose ZERO a combined approach at Network and Link layers to increase network lifespan while conserving reliability levels by means of probabilistic load balancing techniques. Full article
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Open AccessArticle Optical Sensing Properties of Dithiocarbamate-Functionalized Microspheres, Using a Polyvinylpyridine-Polyvinylbenzyl Chloride Copolymer
Sensors 2010, 10(10), 8953-8962; doi:10.3390/s101008953
Received: 12 August 2010 / Revised: 20 September 2010 / Accepted: 25 September 2010 / Published: 8 October 2010
Cited by 1 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a new modified optical chemical sensor based on swellable polymer microspheres is developed using a 5% copolymer of polyvinylpyridine-polyvinyl -benzyl chloride microspheres functionalized as the corresponding dithiocarbamate. This sensor demonstrated significant enhancements in sensitivity, dynamic range and response time. These
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In this study, a new modified optical chemical sensor based on swellable polymer microspheres is developed using a 5% copolymer of polyvinylpyridine-polyvinyl -benzyl chloride microspheres functionalized as the corresponding dithiocarbamate. This sensor demonstrated significant enhancements in sensitivity, dynamic range and response time. These improvements are related to the presence of pyridine in the polymer backbone, which is believed to increase the space between the groups, thus decreasing steric hindrance, and hence increasing substitution of the dithiocarbamate group. The hydrophilicity of pyridine also allows free movement of the solvent and analyte to and from the inside of the microspheres. These dithiocarbamate-derivatized polymer microspheres were embedded in a hydrogel matrix of polyvinylalcohol cross-linked with glutaraldehyde. This sensor responded selectively to Hg2+ solutions of different concentrations (1 × 10−5 M to 0.1 M). The observed turbidity measured as absorbance varied between 1.05 and 1.75 units at a wavelength of 700 nm. The response is based on the interaction between the metal cations with the negative charges of the deprotonated dithiocarbamate functional group, which led to neutratization of the charges and thus to polymer shrinking. As a result, an increase in the turbidity of the sensing element due to a change in the refractive index between the hydrogel and the polymer microspheres occured. The changes in the turbidity of the sensing element were measured as absorbance using a conventional spectrophotometer. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Monitoring System for Vegetable Greenhouses based on a Wireless Sensor Network
Sensors 2010, 10(10), 8963-8980; doi:10.3390/s101008963
Received: 28 July 2010 / Revised: 25 September 2010 / Accepted: 27 September 2010 / Published: 8 October 2010
Cited by 15 | PDF Full-text (658 KB) | HTML Full-text | XML Full-text
Abstract
A wireless sensor network-based automatic monitoring system is designed for monitoring the life conditions of greenhouse vegetatables. The complete system architecture includes a group of sensor nodes, a base station, and an internet data center. For the design of wireless sensor node, the
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A wireless sensor network-based automatic monitoring system is designed for monitoring the life conditions of greenhouse vegetatables. The complete system architecture includes a group of sensor nodes, a base station, and an internet data center. For the design of wireless sensor node, the JN5139 micro-processor is adopted as the core component and the Zigbee protocol is used for wireless communication between nodes. With an ARM7 microprocessor and embedded ZKOS operating system, a proprietary gateway node is developed to achieve data influx, screen display, system configuration and GPRS based remote data forwarding. Through a Client/Server mode the management software for remote data center achieves real-time data distribution and time-series analysis. Besides, a GSM-short-message-based interface is developed for sending real-time environmental measurements, and for alarming when a measurement is beyond some pre-defined threshold. The whole system has been tested for over one year and satisfactory results have been observed, which indicate that this system is very useful for greenhouse environment monitoring. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Study and Evaluation of a PCB-MEMS Liquid Microflow Sensor
Sensors 2010, 10(10), 8981-9001; doi:10.3390/s101008981
Received: 26 July 2010 / Revised: 1 September 2010 / Accepted: 1 September 2010 / Published: 8 October 2010
Cited by 4 | PDF Full-text (1259 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the evaluation of a miniature liquid microflow sensor, directly integrated on a PCB. The sensor operation is based on the convective heat transfer principle. The heating and sensing elements are thin Pt resistors which are in direct electrical contact with
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This paper presents the evaluation of a miniature liquid microflow sensor, directly integrated on a PCB. The sensor operation is based on the convective heat transfer principle. The heating and sensing elements are thin Pt resistors which are in direct electrical contact with the external copper tracks of the printed circuit board. Due to the low thermal conductivity of the substrate material, a high degree of thermal isolation is obtained which improves the operating characteristics of the device. The sensor is able to operate under both the hot-wire and the calorimetric principle. In order to fully exploit the temperature distribution in the flowing liquid, multiple sensing elements are positioned in various distances from the heater. A special housing was developed which allowed implementation of the sensor into tubes of various cross sectional areas. The sensor sensitivity and measurement range as a function of the sensing element distance were quantified. A minimum resolution of 3 μL/min and a measurement flow range up to 500 μL/min were achieved. Full article
Open AccessArticle Experimental Method for Characterizing Electrical Steel Sheets in the Normal Direction
Sensors 2010, 10(10), 9053-9064; doi:10.3390/s101009053
Received: 2 September 2010 / Revised: 15 September 2010 / Accepted: 25 September 2010 / Published: 8 October 2010
Cited by 7 | PDF Full-text (1555 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an experimental method to characterise magnetic laminations in the direction normal to the sheet plane. The principle, which is based on a static excitation to avoid planar eddy currents, is explained and specific test benches are proposed. Measurements of the
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This paper proposes an experimental method to characterise magnetic laminations in the direction normal to the sheet plane. The principle, which is based on a static excitation to avoid planar eddy currents, is explained and specific test benches are proposed. Measurements of the flux density are made with a sensor moving in and out of an air-gap. A simple analytical model is derived in order to determine the permeability in the normal direction. The experimental results for grain oriented steel sheets are presented and a comparison is provided with values obtained from literature. Full article
Open AccessArticle A Data Compression Algorithm for Wireless Sensor Networks Based on an Optimal Order Estimation Model and Distributed Coding
Sensors 2010, 10(10), 9065-9083; doi:10.3390/s101009065
Received: 23 July 2010 / Revised: 10 September 2010 / Accepted: 16 September 2010 / Published: 11 October 2010
Cited by 2 | PDF Full-text (307 KB) | HTML Full-text | XML Full-text
Abstract
In many wireless sensor network applications, the possibility of exceptions occurring is relatively small, so in a normal situation, data obtained at sequential time points by the same node are time correlated, while, spatial correlation may exist in data obtained at the same
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In many wireless sensor network applications, the possibility of exceptions occurring is relatively small, so in a normal situation, data obtained at sequential time points by the same node are time correlated, while, spatial correlation may exist in data obtained at the same time by adjacent nodes. A great deal of node energy will be wasted if data which include time and space correlation is transmitted. Therefore, this paper proposes a data compression algorithm for wireless sensor networks based on optimal order estimation and distributed coding. Sinks can obtain correlation parameters based on optimal order estimation by exploring time and space redundancy included in data which is obtained by sensors. Then the sink restores all data based on time and space correlation parameters and only a little necessary data needs to be transmitted by nodes. Because of the decrease of redundancy, the average energy cost per node will be reduced and the life of the wireless sensor network will obviously be extended as a result. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Sensor Network Data Compression Algorithm Based on Suboptimal Clustering and Virtual Landmark Routing Within Clusters
Sensors 2010, 10(10), 9084-9101; doi:10.3390/s101009084
Received: 9 August 2010 / Revised: 27 August 2010 / Accepted: 27 September 2010 / Published: 11 October 2010
Cited by 1 | PDF Full-text (327 KB) | HTML Full-text | XML Full-text
Abstract
A kind of data compression algorithm for sensor networks based on suboptimal clustering and virtual landmark routing within clusters is proposed in this paper. Firstly, temporal redundancy existing in data obtained by the same node in sequential instants can be eliminated. Then sensor
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A kind of data compression algorithm for sensor networks based on suboptimal clustering and virtual landmark routing within clusters is proposed in this paper. Firstly, temporal redundancy existing in data obtained by the same node in sequential instants can be eliminated. Then sensor networks nodes will be clustered. Virtual node landmarks in clusters can be established based on cluster heads. Routing in clusters can be realized by combining a greedy algorithm and a flooding algorithm. Thirdly, a global structure tree based on cluster heads will be established. During the course of data transmissions from nodes to cluster heads and from cluster heads to sink, the spatial redundancy existing in the data will be eliminated. Only part of the raw data needs to be transmitted from nodes to sink, and all raw data can be recovered in the sink based on a compression code and part of the raw data. Consequently, node energy can be saved, largely because transmission of redundant data can be avoided. As a result the overall performance of the sensor network can obviously be improved. Full article
(This article belongs to the Special Issue Advanced Sensing Technology for Nondestructive Evaluation)
Open AccessArticle Electro‐Quasistatic Analysis of an Electrostatic Induction Micromotor Using the Cell Method
Sensors 2010, 10(10), 9102-9117; doi:10.3390/s101009102
Received: 16 August 2010 / Revised: 29 September 2010 / Accepted: 30 September 2010 / Published: 11 October 2010
PDF Full-text (750 KB) | HTML Full-text | XML Full-text
Abstract
An electro-quasistatic analysis of an induction micromotor has been realized by using the Cell Method. We employed the direct Finite Formulation (FF) of the electromagnetic laws, hence, avoiding a further discretization. The Cell Method (CM) is used for solving the field equations at
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An electro-quasistatic analysis of an induction micromotor has been realized by using the Cell Method. We employed the direct Finite Formulation (FF) of the electromagnetic laws, hence, avoiding a further discretization. The Cell Method (CM) is used for solving the field equations at the entire domain (2D space) of the micromotor. We have reformulated the field laws in a direct FF and analyzed physical quantities to make explicit the relationship between magnitudes and laws. We applied a primal-dual barycentric discretization of the 2D space. The electric potential has been calculated on each node of the primal mesh using CM. For verification purpose, an analytical electric potential equation is introduced as reference. In frequency domain, results demonstrate the error in calculating potential quantity is neglected ( Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Characterization of a Photodiode Coupled with a Si Nanowire-FET on a Plastic Substrate
Sensors 2010, 10(10), 9118-9126; doi:10.3390/s101009118
Received: 29 July 2010 / Revised: 8 September 2010 / Accepted: 19 September 2010 / Published: 12 October 2010
PDF Full-text (689 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, a laterally coupled device composed of a photodiode and a Si nanowires-field-effect transistor (NWs-FET) is constructed on a plastic substrate and the coupled device is characterized. The photodiode is made of p-type Si NWs and an n-type ZnO
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In this study, a laterally coupled device composed of a photodiode and a Si nanowires-field-effect transistor (NWs-FET) is constructed on a plastic substrate and the coupled device is characterized. The photodiode is made of p-type Si NWs and an n-type ZnO film. The Si NWs-FET is connected electrically to the photodiode in order to enhance the latter’s photocurrent efficiency by adjusting the gate voltage of the FET. When the FET is switched on by biasing a gate voltage of −9 V, the photocurrent efficiency of the photodiode is three times higher than that when the FET is switched off by biasing a gate voltage of 0 V. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
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Open AccessArticle Electronic Nose Breathprints Are Independent of Acute Changes in Airway Caliber in Asthma
Sensors 2010, 10(10), 9127-9138; doi:10.3390/s101009127
Received: 10 August 2010 / Revised: 15 September 2010 / Accepted: 25 September 2010 / Published: 12 October 2010
Cited by 18 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
Molecular profiling of exhaled volatile organic compounds (VOC) by electronic nose technology provides breathprints that discriminate between patients with different inflammatory airway diseases, such as asthma and COPD. However, it is unknown whether this is determined by differences in airway caliber. We hypothesized
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Molecular profiling of exhaled volatile organic compounds (VOC) by electronic nose technology provides breathprints that discriminate between patients with different inflammatory airway diseases, such as asthma and COPD. However, it is unknown whether this is determined by differences in airway caliber. We hypothesized that breathprints obtained by electronic nose are independent of acute changes in airway caliber in asthma. Ten patients with stable asthma underwent methacholine provocation (Visit 1) and sham challenge with isotonic saline (Visit 2). At Visit 1, exhaled air was repetitively collected pre-challenge, after reaching the provocative concentration (PC20) causing 20% fall in forced expiratory volume in 1 second (FEV1) and after subsequent salbutamol inhalation. At Visit 2, breath was collected pre-challenge, post-saline and post-salbutamol. At each occasion, an expiratory vital capacity was collected after 5 min of tidal breathing through an inspiratory VOC-filter in a Tedlar bag and sampled by electronic nose (Cyranose 320). Breathprints were analyzed with principal component analysis and individual factors were compared with mixed model analysis followed by pairwise comparisons. Inhalation of methacholine led to a 30.8 ± 3.3% fall in FEV1 and was followed by a significant change in breathprint (p = 0.04). Saline inhalation did not induce a significant change in FEV1, but altered the breathprint (p = 0.01). However, the breathprint obtained after the methacholine provocation was not significantly different from that after saline challenge (p = 0.27). The molecular profile of exhaled air in patients with asthma is altered by nebulized aerosols, but is not affected by acute changes in airway caliber. Our data demonstrate that breathprints by electronic nose are not confounded by the level of airway obstruction. Full article
(This article belongs to the Special Issue Direct and Indirect Sensing of Odor and VOCs and Their Control)
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Open AccessArticle Column-Parallel Correlated Multiple Sampling Circuits for CMOS Image Sensors and Their Noise Reduction Effects
Sensors 2010, 10(10), 9139-9154; doi:10.3390/s101009139
Received: 21 July 2010 / Revised: 3 September 2010 / Accepted: 27 September 2010 / Published: 12 October 2010
Cited by 20 | PDF Full-text (1188 KB) | HTML Full-text | XML Full-text
Abstract
For low-noise complementary metal-oxide-semiconductor (CMOS) image sensors, the reduction of pixel source follower noises is becoming very important. Column-parallel high-gain readout circuits are useful for low-noise CMOS image sensors. This paper presents column-parallel high-gain signal readout circuits, correlated multiple sampling (CMS) circuits and
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For low-noise complementary metal-oxide-semiconductor (CMOS) image sensors, the reduction of pixel source follower noises is becoming very important. Column-parallel high-gain readout circuits are useful for low-noise CMOS image sensors. This paper presents column-parallel high-gain signal readout circuits, correlated multiple sampling (CMS) circuits and their noise reduction effects. In the CMS, the gain of the noise cancelling is controlled by the number of samplings. It has a similar effect to that of an amplified CDS for the thermal noise but is a little more effective for 1/f and RTS noises. Two types of the CMS with simple integration and folding integration are proposed. In the folding integration, the output signal swing is suppressed by a negative feedback using a comparator and one-bit D-to-A converter. The CMS circuit using the folding integration technique allows to realize a very low-noise level while maintaining a wide dynamic range. The noise reduction effects of their circuits have been investigated with a noise analysis and an implementation of a 1Mpixel pinned photodiode CMOS image sensor. Using 16 samplings, dynamic range of 59.4 dB and noise level of 1.9 e- for the simple integration CMS and 75 dB and 2.2 e- for the folding integration CMS, respectively, are obtained. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Method for Direct Measurement of the First-Order Mass Moments of Human Body Segments
Sensors 2010, 10(10), 9155-9162; doi:10.3390/s101009155
Received: 7 July 2010 / Revised: 2 September 2010 / Accepted: 28 September 2010 / Published: 12 October 2010
PDF Full-text (188 KB) | HTML Full-text | XML Full-text
Abstract
We propose a simple and direct method for measuring the first-order mass moment of a human body segment. With the proposed method, the first-order mass moment of the body segment can be directly measured by using only one precision scale and one digital
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We propose a simple and direct method for measuring the first-order mass moment of a human body segment. With the proposed method, the first-order mass moment of the body segment can be directly measured by using only one precision scale and one digital camera. In the dummy mass experiment, the relative standard uncertainty of a single set of measurements of the first-order mass moment is estimated to be 1.7%. The measured value will be useful as a reference for evaluating the uncertainty of the body segment inertial parameters (BSPs) estimated using an indirect method. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessArticle A Zero Velocity Detection Algorithm Using Inertial Sensors for Pedestrian Navigation Systems
Sensors 2010, 10(10), 9163-9178; doi:10.3390/s101009163
Received: 20 August 2010 / Revised: 20 September 2010 / Accepted: 28 September 2010 / Published: 13 October 2010
Cited by 46 | PDF Full-text (727 KB) | HTML Full-text | XML Full-text
Abstract
In pedestrian navigation systems, the position of a pedestrian is computed using an inertial navigation algorithm. In the algorithm, the zero velocity updating plays an important role, where zero velocity intervals are detected and the velocity error is reset. To use the zero
[...] Read more.
In pedestrian navigation systems, the position of a pedestrian is computed using an inertial navigation algorithm. In the algorithm, the zero velocity updating plays an important role, where zero velocity intervals are detected and the velocity error is reset. To use the zero velocity updating, it is necessary to detect zero velocity intervals reliably. A new zero detection algorithm is proposed in the paper, where only one gyroscope value is used. A Markov model is constructed using segmentation of gyroscope outputs instead of using gyroscope outputs directly, which makes the zero velocity detection more reliable. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Development of a Portable Electronic Nose System for the Detection and Classification of Fruity Odors
Sensors 2010, 10(10), 9179-9193; doi:10.3390/s101009179
Received: 12 August 2010 / Revised: 29 September 2010 / Accepted: 8 October 2010 / Published: 15 October 2010
Cited by 26 | PDF Full-text (1221 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we have developed a prototype of a portable electronic nose (E-Nose) comprising a sensor array of eight commercially available sensors, a data acquisition interface PCB, and a microprocessor. Verification software was developed to verify system functions. Experimental results indicate that
[...] Read more.
In this study, we have developed a prototype of a portable electronic nose (E-Nose) comprising a sensor array of eight commercially available sensors, a data acquisition interface PCB, and a microprocessor. Verification software was developed to verify system functions. Experimental results indicate that the proposed system prototype is able to identify the fragrance of three fruits, namely lemon, banana, and litchi. Full article
(This article belongs to the Special Issue Direct and Indirect Sensing of Odor and VOCs and Their Control)
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Open AccessArticle Design of Belief Propagation Based on FPGA for the Multistereo CAFADIS Camera
Sensors 2010, 10(10), 9194-9210; doi:10.3390/s101009194
Received: 18 August 2010 / Revised: 20 September 2010 / Accepted: 29 September 2010 / Published: 15 October 2010
Cited by 5 | PDF Full-text (617 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we describe a fast, specialized hardware implementation of the belief propagation algorithm for the CAFADIS camera, a new plenoptic sensor patented by the University of La Laguna. This camera captures the lightfield of the scene and can be used to
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In this paper we describe a fast, specialized hardware implementation of the belief propagation algorithm for the CAFADIS camera, a new plenoptic sensor patented by the University of La Laguna. This camera captures the lightfield of the scene and can be used to find out at which depth each pixel is in focus. The algorithm has been designed for FPGA devices using VHDL. We propose a parallel and pipeline architecture to implement the algorithm without external memory. Although the BRAM resources of the device increase considerably, we can maintain real-time restrictions by using extremely high-performance signal processing capability through parallelism and by accessing several memories simultaneously. The quantifying results with 16 bit precision have shown that performances are really close to the original Matlab programmed algorithm. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle The Rover Environmental Monitoring Station Ground Temperature Sensor: A Pyrometer for Measuring Ground Temperature on Mars
Sensors 2010, 10(10), 9211-9231; doi:10.3390/s101009211
Received: 27 August 2010 / Revised: 14 September 2010 / Accepted: 25 September 2010 / Published: 15 October 2010
Cited by 8 | PDF Full-text (820 KB) | HTML Full-text | XML Full-text
Abstract
We describe the parameters that drive the design and modeling of the Rover Environmental Monitoring Station (REMS) Ground Temperature Sensor (GTS), an instrument aboard NASA’s Mars Science Laboratory, and report preliminary test results. REMS GTS is a lightweight, low-power, and low cost pyrometer
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We describe the parameters that drive the design and modeling of the Rover Environmental Monitoring Station (REMS) Ground Temperature Sensor (GTS), an instrument aboard NASA’s Mars Science Laboratory, and report preliminary test results. REMS GTS is a lightweight, low-power, and low cost pyrometer for measuring the Martian surface kinematic temperature. The sensor’s main feature is its innovative design, based on a simple mechanical structure with no moving parts. It includes an in-flight calibration system that permits sensor recalibration when sensor sensitivity has been degraded by deposition of dust over the optics. This paper provides the first results of a GTS engineering model working in a Martian-like, extreme environment. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle An Intelligent Architecture Based on Field Programmable Gate Arrays Designed to Detect Moving Objects by Using Principal Component Analysis
Sensors 2010, 10(10), 9232-9251; doi:10.3390/s101009232
Received: 2 September 2010 / Revised: 1 October 2010 / Accepted: 10 October 2010 / Published: 15 October 2010
Cited by 11 | PDF Full-text (518 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a complete implementation of the Principal Component Analysis (PCA) algorithm in Field Programmable Gate Array (FPGA) devices applied to high rate background segmentation of images. The classical sequential execution of different parts of the PCA algorithm has been parallelized. This
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This paper presents a complete implementation of the Principal Component Analysis (PCA) algorithm in Field Programmable Gate Array (FPGA) devices applied to high rate background segmentation of images. The classical sequential execution of different parts of the PCA algorithm has been parallelized. This parallelization has led to the specific development and implementation in hardware of the different stages of PCA, such as computation of the correlation matrix, matrix diagonalization using the Jacobi method and subspace projections of images. On the application side, the paper presents a motion detection algorithm, also entirely implemented on the FPGA, and based on the developed PCA core. This consists of dynamically thresholding the differences between the input image and the one obtained by expressing the input image using the PCA linear subspace previously obtained as a background model. The proposal achieves a high ratio of processed images (up to 120 frames per second) and high quality segmentation results, with a completely embedded and reliable hardware architecture based on commercial CMOS sensors and FPGA devices. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Open AccessArticle Intelligent Sensor Positioning and Orientation Through Constructive Neural Network-Embedded INS/GPS Integration Algorithms
Sensors 2010, 10(10), 9252-9285; doi:10.3390/s101009252
Received: 6 September 2010 / Revised: 30 September 2010 / Accepted: 14 October 2010 / Published: 15 October 2010
Cited by 10 | PDF Full-text (1683 KB) | HTML Full-text | XML Full-text
Abstract
Mobile mapping systems have been widely applied for acquiring spatial information in applications such as spatial information systems and 3D city models. Nowadays the most common technologies used for positioning and orientation of a mobile mapping system include a Global Positioning System (GPS)
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Mobile mapping systems have been widely applied for acquiring spatial information in applications such as spatial information systems and 3D city models. Nowadays the most common technologies used for positioning and orientation of a mobile mapping system include a Global Positioning System (GPS) as the major positioning sensor and an Inertial Navigation System (INS) as the major orientation sensor. In the classical approach, the limitations of the Kalman Filter (KF) method and the overall price of multi-sensor systems have limited the popularization of most land-based mobile mapping applications. Although intelligent sensor positioning and orientation schemes consisting of Multi-layer Feed-forward Neural Networks (MFNNs), one of the most famous Artificial Neural Networks (ANNs), and KF/smoothers, have been proposed in order to enhance the performance of low cost Micro Electro Mechanical System (MEMS) INS/GPS integrated systems, the automation of the MFNN applied has not proven as easy as initially expected. Therefore, this study not only addresses the problems of insufficient automation in the conventional methodology that has been applied in MFNN-KF/smoother algorithms for INS/GPS integrated systems proposed in previous studies, but also exploits and analyzes the idea of developing alternative intelligent sensor positioning and orientation schemes that integrate various sensors in more automatic ways. The proposed schemes are implemented using one of the most famous constructive neural networks––the Cascade Correlation Neural Network (CCNNs)––to overcome the limitations of conventional techniques based on KF/smoother algorithms as well as previously developed MFNN-smoother schemes. The CCNNs applied also have the advantage of a more flexible topology compared to MFNNs. Based on the experimental data utilized the preliminary results presented in this article illustrate the effectiveness of the proposed schemes compared to smoother algorithms as well as the MFNN-smoother schemes. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle Bioconjugation Strategies for Microtoroidal Optical Resonators
Sensors 2010, 10(10), 9317-9336; doi:10.3390/s101009317
Received: 14 September 2010 / Revised: 8 October 2010 / Accepted: 14 October 2010 / Published: 18 October 2010
Cited by 58 | PDF Full-text (1158 KB) | HTML Full-text | XML Full-text
Abstract
The development of label-free biosensors with high sensitivity and specificity is of significant interest for medical diagnostics and environmental monitoring, where rapid and real-time detection of antigens, bacteria, viruses, etc., is necessary. Optical resonant devices, which have very high sensitivity resulting from
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The development of label-free biosensors with high sensitivity and specificity is of significant interest for medical diagnostics and environmental monitoring, where rapid and real-time detection of antigens, bacteria, viruses, etc., is necessary. Optical resonant devices, which have very high sensitivity resulting from their low optical loss, are uniquely suited to sensing applications. However, previous research efforts in this area have focused on the development of the sensor itself. While device sensitivity is an important feature of a sensor, specificity is an equally, if not more, important performance parameter. Therefore, it is crucial to develop a covalent surface functionalization process, which also maintains the device’s sensing capabilities or optical qualities. Here, we demonstrate a facile method to impart specificity to optical microcavities, without adversely impacting their optical performance. In this approach, we selectively functionalize the surface of the silica microtoroids with biotin, using amine-terminated silane coupling agents as linkers. The surface chemistry of these devices is demonstrated using X-ray photoelectron spectroscopy, and fluorescent and optical microscopy. The quality factors of the surface functionalized devices are also characterized to determine the impact of the chemistry methods on the device sensitivity. The resulting devices show uniform surface coverage, with no microstructural damage. This work represents one of the first examples of non-physisorption-based bioconjugation of microtoroidal optical resonators. Full article
(This article belongs to the Special Issue Optical Resonant Microsensors)
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Open AccessArticle Design of a Horizontal Penetrometer for Measuring On‑the‑Go Soil Resistance
Sensors 2010, 10(10), 9337-9348; doi:10.3390/s101009337
Received: 1 September 2010 / Revised: 11 October 2010 / Accepted: 13 October 2010 / Published: 18 October 2010
Cited by 6 | PDF Full-text (807 KB) | HTML Full-text | XML Full-text
Abstract
Soil compaction is one of the main negative factors that limits plant growth and crop yield. Therefore, it is important to determine the soil resistance level and map it for the field to find solutions for the negative effects of the compaction. Nowadays,
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Soil compaction is one of the main negative factors that limits plant growth and crop yield. Therefore, it is important to determine the soil resistance level and map it for the field to find solutions for the negative effects of the compaction. Nowadays, high powered communication technology and computers help us on this issue within the approach of precision agriculture applications. This study is focused on the design of a penetrometer, which can make instantaneous soil resistance measurements in the soil horizontally and data acquisition software based on the GPS (Global Positioning System). The penetrometer was designed using commercial 3D parametric solid modelling design software. The data acquisition software was developed in Microsoft Visual Basic.NET programming language. After the design of the system, manufacturing and assembly of the system was completed and then a field experiment was carried out. According to the data from GPS and penetration resistance values which are collected in Microsoft SQL Server database, a Kriging method by ArcGIS was used and soil resistance was mapped in the field for a soil depth of 40 cm. During operation, no faults, either in mechanical and software parts, were seen. As a result, soil resistance values of 0.2 MPa and 3 MPa were obtained as minimum and maximum values, respectively. In conclusion, the experimental results showed that the designed system works quite well in the field and the horizontal penetrometer is a practical tool for providing on‑line soil resistance measurements. This study contributes to further research for the development of on-line soil resistance measurements and mapping within the precision agriculture applications. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle A Reliable Data Delivery Mechanism for Grid Power Quality Using Neural Networks in Wireless Sensor Networks
Sensors 2010, 10(10), 9349-9358; doi:10.3390/s101009349
Received: 23 August 2010 / Revised: 24 September 2010 / Accepted: 30 September 2010 / Published: 18 October 2010
Cited by 4 | PDF Full-text (433 KB) | HTML Full-text | XML Full-text
Abstract
Power grids deal with the business of generation, transmission, and distribution of electric power. Current systems monitor basic electrical quantities such as voltage and current from major pole transformers using their temperature. We improve the current systems in order to gather and deliver
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Power grids deal with the business of generation, transmission, and distribution of electric power. Current systems monitor basic electrical quantities such as voltage and current from major pole transformers using their temperature. We improve the current systems in order to gather and deliver the information of power qualities such as harmonics, voltage sags, and voltage swells. In the system, data delivery is not guaranteed for the case that a node is lost or the network is congested, because the system has in-line and multi-hop architecture. In this paper, we propose a reliable data delivery mechanism by modeling an optimal data delivery function by employing the neural network concept. Full article
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Open AccessArticle A Sulfur Hexafluoride Sensor Using Quantum Cascade and CO2 Laser-Based Photoacoustic Spectroscopy
Sensors 2010, 10(10), 9359-9368; doi:10.3390/s101009359
Received: 30 August 2010 / Revised: 29 September 2010 / Accepted: 3 October 2010 / Published: 18 October 2010
Cited by 4 | PDF Full-text (223 KB) | HTML Full-text | XML Full-text
Abstract
The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas
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The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m2. This work compares two photoacoustic spectrometers, one coupled to a CO2 laser and another one coupled to a Quantum Cascade (QC) laser, for the detection of SF6. The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO2 laser and 50 ppbv for quantum cascade laser were obtained. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
Open AccessArticle Sensor Data Fusion for Accurate Cloud Presence Prediction Using Dempster-Shafer Evidence Theory
Sensors 2010, 10(10), 9384-9396; doi:10.3390/s101009384
Received: 30 August 2010 / Revised: 15 September 2010 / Accepted: 25 September 2010 / Published: 18 October 2010
Cited by 10 | PDF Full-text (260 KB) | HTML Full-text | XML Full-text
Abstract
Sensor data fusion technology can be used to best extract useful information from multiple sensor observations. It has been widely applied in various applications such as target tracking, surveillance, robot navigation, signal and image processing. This paper introduces a novel data fusion approach
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Sensor data fusion technology can be used to best extract useful information from multiple sensor observations. It has been widely applied in various applications such as target tracking, surveillance, robot navigation, signal and image processing. This paper introduces a novel data fusion approach in a multiple radiation sensor environment using Dempster-Shafer evidence theory. The methodology is used to predict cloud presence based on the inputs of radiation sensors. Different radiation data have been used for the cloud prediction. The potential application areas of the algorithm include renewable power for virtual power station where the prediction of cloud presence is the most challenging issue for its photovoltaic output. The algorithm is validated by comparing the predicted cloud presence with the corresponding sunshine occurrence data that were recorded as the benchmark. Our experiments have indicated that comparing to the approaches using individual sensors, the proposed data fusion approach can increase correct rate of cloud prediction by ten percent, and decrease unknown rate of cloud prediction by twenty three percent. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle E-Beam Patterned Gold Nanodot Arrays on Optical Fiber Tips for Localized Surface Plasmon Resonance Biochemical Sensing
Sensors 2010, 10(10), 9397-9406; doi:10.3390/s101009397
Received: 1 September 2010 / Revised: 30 September 2010 / Accepted: 9 October 2010 / Published: 20 October 2010
Cited by 52 | PDF Full-text (424 KB) | HTML Full-text | XML Full-text
Abstract
Electron beam lithography (EBL) was used to directly pattern periodic gold nanodot arrays on optical fiber tips. Localized surface plasmon resonance of the E-beam patterned gold nanodot arrays on optical fiber tips was utilized for biochemical sensing. The advantage of the optical fiber
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Electron beam lithography (EBL) was used to directly pattern periodic gold nanodot arrays on optical fiber tips. Localized surface plasmon resonance of the E-beam patterned gold nanodot arrays on optical fiber tips was utilized for biochemical sensing. The advantage of the optical fiber based localized surface plasmon resonance (LSPR) sensors is the convenience to work with and work in harsh environments. An optical fiber tip LSPR refractive index sensor of 196 nm per refractive index unit (RIU) sensitivity has been demonstrated. The affinity sensing property of the fiber tip sensor was demonstrated using biotin/streptavidin as the receptor/analyte. The detection limit for streptavidin was determined to be 6 pM. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Fiber Bragg Grating Sensor for Fault Detection in Radial and Network Transmission Lines
Sensors 2010, 10(10), 9407-9423; doi:10.3390/s101009407
Received: 5 September 2010 / Revised: 1 October 2010 / Accepted: 8 October 2010 / Published: 20 October 2010
Cited by 4 | PDF Full-text (348 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated
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In this paper, a fiber optic based sensor capable of fault detection in both radial and network overhead transmission power line systems is investigated. Bragg wavelength shift is used to measure the fault current and detect fault in power systems. Magnetic fields generated by currents in the overhead transmission lines cause a strain in magnetostrictive material which is then detected by Fiber Bragg Grating (FBG). The Fiber Bragg interrogator senses the reflected FBG signals, and the Bragg wavelength shift is calculated and the signals are processed. A broadband light source in the control room scans the shift in the reflected signal. Any surge in the magnetic field relates to an increased fault current at a certain location. Also, fault location can be precisely defined with an artificial neural network (ANN) algorithm. This algorithm can be easily coordinated with other protective devices. It is shown that the faults in the overhead transmission line cause a detectable wavelength shift on the reflected signal of FBG and can be used to detect and classify different kind of faults. The proposed method has been extensively tested by simulation and results confirm that the proposed scheme is able to detect different kinds of fault in both radial and network system. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle An Integration of GPS with INS Sensors for Precise Long-Baseline Kinematic Positioning
Sensors 2010, 10(10), 9424-9438; doi:10.3390/s101009424
Received: 3 September 2010 / Revised: 8 October 2010 / Accepted: 19 October 2010 / Published: 20 October 2010
Cited by 6 | PDF Full-text (720 KB) | HTML Full-text | XML Full-text
Abstract
Integrating the precise GPS carrier phases and INS sensor technologies is a methodology that has been applied indispensably in those application fields requiring accurate and reliable position, velocity, and attitude information. However, conventional integration approaches with a single GPS reference station may not
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Integrating the precise GPS carrier phases and INS sensor technologies is a methodology that has been applied indispensably in those application fields requiring accurate and reliable position, velocity, and attitude information. However, conventional integration approaches with a single GPS reference station may not fulfil the demanding performance requirements, especially in the position component, when the baseline length between the reference station and mobile user’s GPS receiver is greater than a few tens of kilometres. This is because their positioning performance is primarily dependent on the common mode of errors of GPS measurements. To address this constraint, a novel GPS/INS integration scheme using multiple GPS reference stations is proposed here that can improve its positioning accuracy by modelling the baseline-dependent errors. In this paper, the technical issues concerned with implementing the proposed scheme are described, including the GPS network correction modelling and integrated GPS/INS filtering. In addition, the results from the processing of the simulated measurements are presented to characterise the system performance. As a result, it has been established that the integration of GPS/INS with multiple reference stations would make it possible to ensure centimetre-level positioning accuracy, even if the baseline length reaches about 100 km. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Development of an Electrochemical Biosensor for the Detection of Aflatoxin M1 in Milk
Sensors 2010, 10(10), 9439-9448; doi:10.3390/s101009439
Received: 9 September 2010 / Revised: 30 September 2010 / Accepted: 10 October 2010 / Published: 20 October 2010
Cited by 31 | PDF Full-text (482 KB) | HTML Full-text | XML Full-text
Abstract
We have developed an electrochemical immunosensor for the detection of ultratrace amounts of aflatoxin M1 (AFM1) in food products. The sensor was based on a competitive immunoassay using horseradish peroxidase (HRP) as a tag. Magnetic nanoparticles coated with antibody (anti-AFM
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We have developed an electrochemical immunosensor for the detection of ultratrace amounts of aflatoxin M1 (AFM1) in food products. The sensor was based on a competitive immunoassay using horseradish peroxidase (HRP) as a tag. Magnetic nanoparticles coated with antibody (anti-AFM1) were used to separate the bound and unbound fractions. The samples containing AFM1 were incubated with a fixed amount of antibody and tracer [AFM1 linked to HRP (conjugate)] until the system reached equilibrium. Competition occurs between the antigen (AFM1) and the conjugate for the antibody. Then, the mixture was deposited on the surface of screen-printed carbon electrodes, and the mediator [5-methylphenazinium methyl sulphate (MPMS)] was added. The enzymatic response was measured amperometrically. A standard range (0, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.3, 0.4 and 0.5 ppb) of AFM1-contaminated milk from the ELISA kit was used to obtain a standard curve for AFM1. To test the detection sensitivity of our sensor, samples of commercial milk were supplemented at 0.01, 0.025, 0.05 or 0.1 ppb with AFM1. Our immunosensor has a low detection limit (0.01 ppb), which is under the recommended level of AFM1 [0.05 µg L-1 (ppb)], and has good reproducibility. Full article
(This article belongs to the Special Issue Bio-devices and Materials)
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Open AccessArticle Determination of Anthracene on Ag-Au Alloy Nanoparticles/Overoxidized-Polypyrrole Composite Modified Glassy Carbon Electrodes
Sensors 2010, 10(10), 9449-9465; doi:10.3390/s101009449
Received: 16 July 2010 / Revised: 31 August 2010 / Accepted: 10 September 2010 / Published: 20 October 2010
Cited by 14 | PDF Full-text (545 KB) | HTML Full-text | XML Full-text
Abstract
A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by
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A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by its overoxidation in 0.1 M NaOH. Ag-Au bimetallic nanoparticles were chemically prepared by the reduction of AgNO3 and HAuCl4 using C6H5O7Na3 as the reducing agent as well as the capping agent and then immobilized on the surface of the PPyox/GCE. The nanoparticles were characterized by UV-visible spectroscopy technique which confirmed the homogeneous formation of the bimetallic alloy nanoparticles. Transmission electron microscopy showed that the synthesized bimetallic nanoparticles were in the range of 20–50 nm. The electrochemical behaviour of anthracene at the PPyox/Ag-AuNPs/GCE with Ag: Au atomic ratio 25:75 (1:3) exhibited a higher electrocatalytic effect compared to that observed when GCE was modified with each constituent of the composite (i.e., PPyox, Ag-AuNPs) and bare GCE. A linear relationship between anodic current and anthracene concentration was attained over the range of 3.0 × 10−6 to 3.56 × 10−4 M with a detection limit of 1.69 × 10−7 M. The proposed method was simple, less time consuming and showed a high sensitivity. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Schedule-based Multi-channel MAC Protocol for Wireless Sensor Networks
Sensors 2010, 10(10), 9466-9480; doi:10.3390/s101009466
Received: 10 September 2010 / Revised: 13 October 2010 / Accepted: 14 October 2010 / Published: 21 October 2010
Cited by 2 | PDF Full-text (345 KB) | HTML Full-text | XML Full-text
Abstract
Due to the half-duplex property of the sensor radio and the broadcast nature of wireless medium, limited bandwidth remains a pressing issue for wireless sensor networks (WSNs). The design of multi-channel MAC protocols has attracted the interest of many researchers as a cost
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Due to the half-duplex property of the sensor radio and the broadcast nature of wireless medium, limited bandwidth remains a pressing issue for wireless sensor networks (WSNs). The design of multi-channel MAC protocols has attracted the interest of many researchers as a cost effective solution to meet the higher bandwidth demand for the limited bandwidth in WSN. In this paper, we present a scheduled-based multi-channel MAC protocol to improve network performance. In our protocol, each receiving node selects (schedules) some timeslot(s), in which it may receive data from the intending sender(s). The timeslot selection is done in a conflict free manner, where a node avoids the slots that are already selected by others in its interference range. To minimize the conflicts during timeslot selection, we propose a unique solution by splitting the neighboring nodes into different groups, where nodes of a group may select the slots allocated to that group only. We demonstrate the effectiveness of our approach thorough simulations in terms of performance parameters such as aggregate throughput, packet delivery ratio, end-to-end delay, and energy consumption. Full article
Open AccessArticle Study on a Luminol-based Electrochemiluminescent Sensor for Label-Free DNA Sensing
Sensors 2010, 10(10), 9481-9492; doi:10.3390/s101009481
Received: 18 August 2010 / Revised: 25 September 2010 / Accepted: 8 October 2010 / Published: 21 October 2010
Cited by 5 | PDF Full-text (331 KB) | HTML Full-text | XML Full-text
Abstract
Automatic, inexpensive, simple and sensitive methods for DNA sensing and quantification are highly desirable for biomedical research. The rapid development of both the fundamentals and applications of electrochemiluminescence (ECL) over the past years has demonstrated its potential for analytical and bio-analytical chemistry. This
[...] Read more.
Automatic, inexpensive, simple and sensitive methods for DNA sensing and quantification are highly desirable for biomedical research. The rapid development of both the fundamentals and applications of electrochemiluminescence (ECL) over the past years has demonstrated its potential for analytical and bio-analytical chemistry. This paper reports the quenching effect of DNA on the ECL of luminol and the further development of a DNA sensing device. With the pre-functionalization by a composite of carbon nano-tubes (CNTs) and Au nanoparticles (AuNPs), the sensor provides a novel and valuable label-free approach for DNA sensing. Here the ECL intensity was remarkably decreased when more than 1.0 × 10−12 molar of DNA were adsorbed on the sensor. Linearity of the DNA amount with the reciprocal of ECL intensity was observed. A saturated sensor caused a 92.8% quenching effect. The research also proposes the mechanism for the quenching effect which could be attributed to the interaction between luminol and DNA and the elimination of reactive oxygen species (ROSs) by DNA. Full article
Open AccessArticle A Distance-Based Energy Aware Routing Algorithm for Wireless Sensor Networks
Sensors 2010, 10(10), 9493-9511; doi:10.3390/s101009493
Received: 4 August 2010 / Revised: 20 September 2010 / Accepted: 19 October 2010 / Published: 21 October 2010
Cited by 12 | PDF Full-text (389 KB) | HTML Full-text | XML Full-text
Abstract
Energy efficiency and balancing is one of the primary challenges for wireless sensor networks (WSNs) since the tiny sensor nodes cannot be easily recharged once they are deployed. Up to now, many energy efficient routing algorithms or protocols have been proposed with techniques
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Energy efficiency and balancing is one of the primary challenges for wireless sensor networks (WSNs) since the tiny sensor nodes cannot be easily recharged once they are deployed. Up to now, many energy efficient routing algorithms or protocols have been proposed with techniques like clustering, data aggregation and location tracking etc. However, many of them aim to minimize parameters like total energy consumption, latency etc., which cause hotspot nodes and partitioned network due to the overuse of certain nodes. In this paper, a Distance-based Energy Aware Routing (DEAR) algorithm is proposed to ensure energy efficiency and energy balancing based on theoretical analysis of different energy and traffic models. During the routing process, we consider individual distance as the primary parameter in order to adjust and equalize the energy consumption among involved sensors. The residual energy is also considered as a secondary factor. In this way, all the intermediate nodes will consume their energy at similar rate, which maximizes network lifetime. Simulation results show that the DEAR algorithm can reduce and balance the energy consumption for all sensor nodes so network lifetime is greatly prolonged compared to other routing algorithms. Full article
Open AccessArticle Image Reconstruction of a Charge Coupled Device Based Optical Tomographic Instrumentation System for Particle Sizing
Sensors 2010, 10(10), 9512-9528; doi:10.3390/s101009512
Received: 5 September 2010 / Revised: 5 October 2010 / Accepted: 15 October 2010 / Published: 22 October 2010
Cited by 5 | PDF Full-text (275 KB) | HTML Full-text | XML Full-text
Abstract
This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. The measurement system, consisting of four CCD linear image sensors are configured around an octagonal shaped flow pipe
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This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. The measurement system, consisting of four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system is explained. The four linear image sensors provide 2,048 pixel imaging with a pixel size of 14 micron × 14 micron, hence constituting a high-resolution system. Image reconstruction for a four-projection optical tomography system is also discussed, where a simple optical model is used to relate attenuation due to variations in optical density, [R], within the measurement section. Expressed in matrix form this represents the forward problem in tomography [S] [R] = [M]. In practice, measurements [M] are used to estimate the optical density distribution by solving the inverse problem [R] = [S]−1[M]. Direct inversion of the sensitivity matrix, [S], is not possible and two approximations are considered and compared—the transpose and the pseudo inverse sensitivity matrices. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Feedback-Based Secure Path Approach for Wireless Sensor Network Data Collection
Sensors 2010, 10(10), 9529-9540; doi:10.3390/s101009529
Received: 16 August 2010 / Revised: 13 September 2010 / Accepted: 19 October 2010 / Published: 22 October 2010
Cited by 3 | PDF Full-text (517 KB) | HTML Full-text | XML Full-text
Abstract
The unattended nature of wireless sensor networks makes them very vulnerable to malicious attacks. Therefore, how to preserve secure data collection is an important issue to wireless sensor networks. In this paper, we propose a novel approach of secure data collection for wireless
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The unattended nature of wireless sensor networks makes them very vulnerable to malicious attacks. Therefore, how to preserve secure data collection is an important issue to wireless sensor networks. In this paper, we propose a novel approach of secure data collection for wireless sensor networks. We explore secret sharing and multipath routing to achieve secure data collection in wireless sensor network with compromised nodes. We present a novel tracing-feedback mechanism, which makes full use of the routing functionality of wireless sensor networks, to improve the quality of data collection. The major advantage of the approach is that the secure paths are constructed as a by-product of data collection. The process of secure routing causes little overhead to the sensor nodes in the network. Compared with existing works, the algorithms of the proposed approach are easy to implement and execute in resource-constrained wireless sensor networks. According to the result of a simulation experiment, the performance of the approach is better than the recent approaches with a similar purpose. Full article

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Open AccessReview Metal-Insulator-Semiconductor Photodetectors
Sensors 2010, 10(10), 8797-8826; doi:10.3390/s101008797
Received: 5 August 2010 / Revised: 7 September 2010 / Accepted: 14 September 2010 / Published: 28 September 2010
Cited by 54 | PDF Full-text (970 KB) | HTML Full-text | XML Full-text
Abstract
The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark
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The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessReview A Smart Checkpointing Scheme for Improving the Reliability of Clustering Routing Protocols
Sensors 2010, 10(10), 8938-8952; doi:10.3390/s101008938
Received: 22 July 2010 / Revised: 13 September 2010 / Accepted: 28 September 2010 / Published: 29 September 2010
Cited by 3 | PDF Full-text (639 KB) | HTML Full-text | XML Full-text
Abstract
In wireless sensor networks, system architectures and applications are designed to consider both resource constraints and scalability, because such networks are composed of numerous sensor nodes with various sensors and actuators, small memories, low-power microprocessors, radio modules, and batteries. Clustering routing protocols based
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In wireless sensor networks, system architectures and applications are designed to consider both resource constraints and scalability, because such networks are composed of numerous sensor nodes with various sensors and actuators, small memories, low-power microprocessors, radio modules, and batteries. Clustering routing protocols based on data aggregation schemes aimed at minimizing packet numbers have been proposed to meet these requirements. In clustering routing protocols, the cluster head plays an important role. The cluster head collects data from its member nodes and aggregates the collected data. To improve reliability and reduce recovery latency, we propose a checkpointing scheme for the cluster head. In the proposed scheme, backup nodes monitor and checkpoint the current state of the cluster head periodically. We also derive the checkpointing interval that maximizes reliability while using the same amount of energy consumed by clustering routing protocols that operate without checkpointing. Experimental comparisons with existing non-checkpointing schemes show that our scheme reduces both energy consumption and recovery latency. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessReview Glucose Sensing Neurons in the Ventromedial Hypothalamus
Sensors 2010, 10(10), 9002-9025; doi:10.3390/s101009002
Received: 10 August 2010 / Revised: 15 September 2010 / Accepted: 18 September 2010 / Published: 8 October 2010
Cited by 31 | PDF Full-text (155 KB) | HTML Full-text | XML Full-text
Abstract
Neurons whose activity is regulated by glucose are found in a number of brain regions. Glucose-excited (GE) neurons increase while glucose-inhibited (GI) neurons decrease their action potential frequency as interstitial brain glucose levels increase. We hypothesize that these neurons evolved to sense and
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Neurons whose activity is regulated by glucose are found in a number of brain regions. Glucose-excited (GE) neurons increase while glucose-inhibited (GI) neurons decrease their action potential frequency as interstitial brain glucose levels increase. We hypothesize that these neurons evolved to sense and respond to severe energy deficit (e.g., fasting) that threatens the brains glucose supply. During modern times, they are also important for the restoration of blood glucose levels following insulin-induced hypoglycemia. Our data suggest that impaired glucose sensing by hypothalamic glucose sensing neurons may contribute to the syndrome known as hypoglycemia-associated autonomic failure in which the mechanisms which restore euglycemia following hypoglycemia become impaired. On the other hand, increased responses of glucose sensing neurons to glucose deficit may play a role in the development of Type 2 Diabetes Mellitus and obesity. This review will discuss the mechanisms by which glucose sensing neurons sense changes in interstitial glucose and explore the roles of these specialized glucose sensors in glucose and energy homeostasis. Full article
(This article belongs to the Special Issue Glucose Sensors)
Open AccessReview Wearable Systems for Monitoring Mobility-Related Activities in Chronic Disease: A Systematic Review
Sensors 2010, 10(10), 9026-9052; doi:10.3390/s101009026
Received: 15 August 2010 / Revised: 2 September 2010 / Accepted: 20 September 2010 / Published: 8 October 2010
Cited by 27 | PDF Full-text (207 KB) | HTML Full-text | XML Full-text
Abstract
The use of wearable motion sensing technology offers important advantages over conventional methods for obtaining measures of physical activity and/or physical functioning in individuals with chronic diseases. This review aims to identify the actual state of applying wearable systems for monitoring mobility-related activity
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The use of wearable motion sensing technology offers important advantages over conventional methods for obtaining measures of physical activity and/or physical functioning in individuals with chronic diseases. This review aims to identify the actual state of applying wearable systems for monitoring mobility-related activity in individuals with chronic disease conditions. In this review we focus on technologies and applications, feasibility and adherence aspects, and clinical relevance of wearable motion sensing technology. PubMed (Medline since 1990), PEdro, and reference lists of all relevant articles were searched. Two authors independently reviewed randomised trials systematically. The quality of selected articles was scored and study results were summarised and discussed. 163 abstracts were considered. After application of inclusion criteria and full text reading, 25 articles were taken into account in a full text review. Twelve of these papers evaluated walking with pedometers, seven used uniaxial accelerometers to assess physical activity, six used multiaxial accelerometers, and two papers used a combination approach of a pedometer and a multiaxial accelerometer for obtaining overall activity and energy expenditure measures. Seven studies mentioned feasibility and/or adherence aspects. The number of studies that use movement sensors for monitoring of activity patterns in chronic disease (postural transitions, time spent in certain positions or activities) is nonexistent on the RCT level of study design. Although feasible methods for monitoring human mobility are available, evidence-based clinical applications of these methods in individuals with chronic diseases are in need of further development. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
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Open AccessReview Optical Oxygen Sensors for Applications in Microfluidic Cell Culture
Sensors 2010, 10(10), 9286-9316; doi:10.3390/s101009286
Received: 16 August 2010 / Revised: 17 September 2010 / Accepted: 10 October 2010 / Published: 15 October 2010
Cited by 56 | PDF Full-text (2436 KB) | HTML Full-text | XML Full-text
Abstract
The presence and concentration of oxygen in biological systems has a large impact on the behavior and viability of many types of cells, including the differentiation of stem cells or the growth of tumor cells. As a result, the integration of oxygen sensors
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The presence and concentration of oxygen in biological systems has a large impact on the behavior and viability of many types of cells, including the differentiation of stem cells or the growth of tumor cells. As a result, the integration of oxygen sensors within cell culture environments presents a powerful tool for quantifying the effects of oxygen concentrations on cell behavior, cell viability, and drug effectiveness. Because microfluidic cell culture environments are a promising alternative to traditional cell culture platforms, there is recent interest in integrating oxygen-sensing mechanisms with microfluidics for cell culture applications. Optical, luminescence-based oxygen sensors, in particular, show great promise in their ability to be integrated with microfluidics and cell culture systems. These sensors can be highly sensitive and do not consume oxygen or generate toxic byproducts in their sensing process. This paper presents a review of previously proposed optical oxygen sensor types, materials and formats most applicable to microfluidic cell culture, and analyzes their suitability for this and other in vitro applications. Full article
(This article belongs to the Special Issue Bio-devices and Materials)
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Open AccessReview Biomedical Use of Isothermal Microcalorimeters
Sensors 2010, 10(10), 9369-9383; doi:10.3390/s101009369
Received: 29 July 2010 / Revised: 23 August 2010 / Accepted: 30 September 2010 / Published: 18 October 2010
Cited by 27 | PDF Full-text (306 KB) | HTML Full-text | XML Full-text
Abstract
Isothermal microcalorimetry is becoming widely used for monitoring biological activities in vitro. Microcalorimeters are now able to measure heat production rates of less than a microwatt. As a result, metabolism and growth of relatively small numbers of cultured bacteria, protozoans, human cells
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Isothermal microcalorimetry is becoming widely used for monitoring biological activities in vitro. Microcalorimeters are now able to measure heat production rates of less than a microwatt. As a result, metabolism and growth of relatively small numbers of cultured bacteria, protozoans, human cells and even small animals can be monitored continuously and extremely accurately at any chosen temperature. Dynamic effects on these organisms of changes in the culture environment—or of additions to it—are easily assessed over periods from hours to days. In addition microcalorimetry is a non-destructive method that does not require much sample preparation. It is also completely passive and thus allows subsequent evaluations of any kind on the undisturbed sample. In this review, we present a basic description of current microcalorimetry instruments and an overview of their use for various biomedical applications. These include detecting infections, evaluating effects of pharmaceutical or antimicrobial agents on cells, monitoring growth of cells harvested for tissue eingineering, and assessing medical and surgical device material physico-chemical stability and cellular biocompatibility. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)

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