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Sensors, Volume 10, Issue 4 (April 2010), Pages 2460-4179

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Open AccessArticle Estimation of Biological Oxygen Demand and Chemical Oxygen Demand for Combined Sewer Systems Using Synchronous Fluorescence Spectra
Sensors 2010, 10(4), 2460-2471; doi:10.3390/s100402460
Received: 21 January 2010 / Revised: 1 March 2010 / Accepted: 6 March 2010 / Published: 24 March 2010
Cited by 22 | PDF Full-text (222 KB) | HTML Full-text | XML Full-text
Abstract
Real-time monitoring of water quality for sewer system is required for efficient sewer network design because it provides information on the precise loading of pollutant to wastewater treatment facilities and the impact of loading on receiving water. In this study, synchronous fluorescence spectra
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Real-time monitoring of water quality for sewer system is required for efficient sewer network design because it provides information on the precise loading of pollutant to wastewater treatment facilities and the impact of loading on receiving water. In this study, synchronous fluorescence spectra and its first derivatives were investigated using a number of wastewater samples collected in sewer systems in urban and non-urban areas, and the optimum fluorescence feature was explored for the estimation of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations of sewer samples. The temporal variations in BOD and COD showed a regular pattern for urban areas whereas they were relatively irregular for non-urban areas. Irrespective of the sewer pipes and the types of the areas, two distinct peaks were identified from the synchronous fluorescence spectra, which correspond to protein-like fluorescence (PLF) and humic-like fluorescence (HLF), respectively. HLF in sewer samples appears to be associated with fluorescent whitening agents. Five fluorescence characteristics were selected from the synchronous spectra and the first-derivatives. Among the selected fluorescence indices, a peak in the PLF region (i.e., Index I) showed the highest correlation coefficient with both BOD and COD. A multiple regression approach based on suspended solid (SS) and Index I used to compensate for the contribution of SS to BOD and COD revealed an improvement in the estimation capability, showing good correlation coefficients of 0.92 and 0.94 for BOD and COD, respectively. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle Development of a Low-Cost Attitude and Heading Reference System Using a Three-Axis Rotating Platform
Sensors 2010, 10(4), 2472-2491; doi:10.3390/s100402472
Received: 12 January 2010 / Revised: 3 March 2010 / Accepted: 19 March 2010 / Published: 24 March 2010
Cited by 39 | PDF Full-text (390 KB) | HTML Full-text | XML Full-text
Abstract
A development procedure for a low-cost attitude and heading reference system (AHRS) with a self-developed three-axis rotating platform has been proposed. The AHRS consists of one 3-axis accelerometer, three single-axis gyroscopes, and one 3-axis digital compass. Both the accelerometer and gyroscope triads are
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A development procedure for a low-cost attitude and heading reference system (AHRS) with a self-developed three-axis rotating platform has been proposed. The AHRS consists of one 3-axis accelerometer, three single-axis gyroscopes, and one 3-axis digital compass. Both the accelerometer and gyroscope triads are based on micro electro-mechanical system (MEMS) technology, and the digital compass is based on anisotropic-magnetoresistive (AMR) technology. The calibrations for each sensor triad are readily accomplished by using the scalar calibration and the least squares methods. The platform is suitable for the calibration and validation of the low-cost AHRS and it is affordable for most laboratories. With the calibrated parameters and data fusion algorithm for the orientation estimation, the self-developed AHRS demonstrates the capabilities of compensating for the sensor errors and outputting the estimated orientation in real-time. The validation results show that the estimated orientations of the developed AHRS are within the acceptable region. This verifies the practicability of the proposed development procedure. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle The Comparison of Environmental Effects on Michelson and Fabry-Perot Interferometers Utilized for the Displacement Measurement
Sensors 2010, 10(4), 2577-2586; doi:10.3390/s100402577
Received: 29 January 2010 / Revised: 10 March 2010 / Accepted: 16 March 2010 / Published: 24 March 2010
Cited by 11 | PDF Full-text (388 KB) | HTML Full-text | XML Full-text
Abstract
The optical structure of general commercial interferometers, e.g., the Michelson interferometers, is based on a non-common optical path. Such interferometers suffer from environmental effects because of the different phase changes induced in different optical paths and consequently the measurement precision will be significantly
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The optical structure of general commercial interferometers, e.g., the Michelson interferometers, is based on a non-common optical path. Such interferometers suffer from environmental effects because of the different phase changes induced in different optical paths and consequently the measurement precision will be significantly influenced by tiny variations of the environmental conditions. Fabry-Perot interferometers, which feature common optical paths, are insensitive to environmental disturbances. That would be advantageous for precision displacement measurements under ordinary environmental conditions. To verify and analyze this influence, displacement measurements with the two types of interferometers, i.e., a self-fabricated Fabry-Perot interferometer and a commercial Michelson interferometer, have been performed and compared under various environmental disturbance scenarios. Under several test conditions, the self-fabricated Fabry-Perot interferometer was obviously less sensitive to environmental disturbances than a commercial Michelson interferometer. Experimental results have shown that induced errors from environmental disturbances in a Fabry-Perot interferometer are one fifth of those in a Michelson interferometer. This has proved that an interferometer with the common optical path structure will be much more independent of environmental disturbances than those with a non-common optical path structure. It would be beneficial for the solution of interferometers utilized for precision displacement measurements in ordinary measurement environments. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle A Multi-Point Sensor Based on Optical Fiber for the Measurement of Electrolyte Density in Lead-Acid Batteries
Sensors 2010, 10(4), 2587-2608; doi:10.3390/s100402587
Received: 26 January 2010 / Revised: 10 March 2010 / Accepted: 16 March 2010 / Published: 25 March 2010
Cited by 15 | PDF Full-text (742 KB) | HTML Full-text | XML Full-text
Abstract
This article describes a multi-point optical fiber-based sensor for the measurement of electrolyte density in lead-acid batteries. It is known that the battery charging process creates stratification, due to the different densities of sulphuric acid and water. In order to study this process,
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This article describes a multi-point optical fiber-based sensor for the measurement of electrolyte density in lead-acid batteries. It is known that the battery charging process creates stratification, due to the different densities of sulphuric acid and water. In order to study this process, density measurements should be obtained at different depths. The sensor we describe in this paper, unlike traditional sensors, consists of several measurement points, allowing density measurements at different depths inside the battery. The obtained set of measurements helps in determining the charge (SoC) and state of health (SoH) of the battery. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Vertical Guidance Performance Analysis of the L1-L5 Dual-Frequency GPS/WAAS User Avionics Sensor
Sensors 2010, 10(4), 2609-2625; doi:10.3390/s100402609
Received: 12 January 2010 / Revised: 13 February 2010 / Accepted: 27 February 2010 / Published: 25 March 2010
Cited by 4 | PDF Full-text (658 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates the potential vertical guidance performance of global positioning system (GPS)/wide area augmentation system (WAAS) user avionics sensor when the modernized GPS and Galileo are available. This paper will first investigate the airborne receiver code noise and multipath (CNMP) confidence (
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This paper investigates the potential vertical guidance performance of global positioning system (GPS)/wide area augmentation system (WAAS) user avionics sensor when the modernized GPS and Galileo are available. This paper will first investigate the airborne receiver code noise and multipath (CNMP) confidence (σair). The σair will be the dominant factor in the availability analysis of an L1-L5 dual-frequency GPS/WAAS user avionics sensor. This paper uses the MATLAB Algorithm Availability Simulation Tool (MAAST) to determine the required values for the σair, so that an L1-L5 dual-frequency GPS/WAAS user avionics sensor can meet the vertical guidance requirements of APproach with Vertical guidance (APV) II and CATegory (CAT) I over conterminous United States (CONUS). A modified MAAST that includes the Galileo satellite constellation is used to determine under what user configurations WAAS could be an APV II system or a CAT I system over CONUS. Furthermore, this paper examines the combinations of possible improvements in signal models and the addition of Galileo to determine if GPS/WAAS user avionics sensor could achieve 10 m Vertical Alert Limit (VAL) within the service volume. Finally, this paper presents the future vertical guidance performance of GPS user avionics sensor for the United States’ WAAS, Japanese MTSAT-based satellite augmentation system (MSAS) and European geostationary navigation overlay service (EGNOS). Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Following Enzyme Activity with Infrared Spectroscopy
Sensors 2010, 10(4), 2626-2637; doi:10.3390/s100402626
Received: 24 January 2010 / Revised: 20 February 2010 / Accepted: 6 March 2010 / Published: 25 March 2010
Cited by 21 | PDF Full-text (175 KB) | HTML Full-text | XML Full-text
Abstract
Fourier transform infrared (FTIR) spectroscopy provides a direct, "on-line" monitor of enzymatic reactions. Measurement of enzymatic activity is based on the fact that the infrared spectra of reactants and products of an enzymatic reaction are usually different. Several examples are given using the
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Fourier transform infrared (FTIR) spectroscopy provides a direct, "on-line" monitor of enzymatic reactions. Measurement of enzymatic activity is based on the fact that the infrared spectra of reactants and products of an enzymatic reaction are usually different. Several examples are given using the enzymes pyruvate kinase, fumarase and alcohol dehydrogenase. The main advantage of the infrared method is that it observes the reaction of interest directly, i.e.,no activity assay is required to convert the progress of the reaction into an observable quantity. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessArticle Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy
Sensors 2010, 10(4), 2675-2693; doi:10.3390/s100402675
Received: 13 January 2010 / Revised: 28 January 2010 / Accepted: 2 March 2010 / Published: 25 March 2010
Cited by 8 | PDF Full-text (673 KB) | HTML Full-text | XML Full-text
Abstract
This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke
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This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Infrared Spectroscopy on Smoke Produced by Cauterization of Animal Tissue
Sensors 2010, 10(4), 2694-2708; doi:10.3390/s100402694
Received: 24 January 2010 / Revised: 20 February 2010 / Accepted: 19 March 2010 / Published: 26 March 2010
Cited by 11 | PDF Full-text (7238 KB) | HTML Full-text | XML Full-text
Abstract
In view of in vivo surgical smoke studies a difference-frequency-generation (DFG) laser spectrometer (spectral range 2900–3144 cm-1) and a Fourier-transform infrared (FTIR) spectrometer were employed for infrared absorption spectroscopy. The chemical composition of smoke produced in vitro with an electroknife by
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In view of in vivo surgical smoke studies a difference-frequency-generation (DFG) laser spectrometer (spectral range 2900–3144 cm-1) and a Fourier-transform infrared (FTIR) spectrometer were employed for infrared absorption spectroscopy. The chemical composition of smoke produced in vitro with an electroknife by cauterization of different animal tissues in different atmospheres was investigated. Average concentrations derived are: water vapor (0.87%), methane (20 ppm), ethane (4.8 ppm), ethene (17 ppm), carbon monoxide (190 ppm), nitric oxide (25 ppm), nitrous oxide (40 ppm), ethyne (50 ppm) and hydrogen cyanide (25 ppm). No correlation between smoke composition and the atmosphere or the kind of cauterized tissue was found. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle In/Out Status Monitoring in Mobile Asset Tracking with Wireless Sensor Networks
Sensors 2010, 10(4), 2709-2730; doi:10.3390/s100402709
Received: 28 January 2010 / Revised: 20 February 2010 / Accepted: 8 March 2010 / Published: 26 March 2010
Cited by 2 | PDF Full-text (535 KB) | HTML Full-text | XML Full-text
Abstract
A mobile asset with a sensor node in a mobile asset tracking system moves around a monitoring area, leaves it, and then returns to the region repeatedly. The system monitors the in/out status of the mobile asset. Due to the continuous movement of
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A mobile asset with a sensor node in a mobile asset tracking system moves around a monitoring area, leaves it, and then returns to the region repeatedly. The system monitors the in/out status of the mobile asset. Due to the continuous movement of the mobile asset, the system may generate an error for the in/out status of the mobile asset. When the mobile asset is inside the region, the system might determine that it is outside, or vice versa. In this paper, we propose a method to detect and correct the incorrect in/out status of the mobile asset. To solve this problem, our approach uses data about the connection state transition and the battery lifetime of the mobile node attached to the mobile asset. The connection state transition is used to classify the mobile node as normal or abnormal. The battery lifetime is used to predict a valid working period for the mobile node. We evaluate our method using real data generated by a medical asset tracking system. The experimental results show that our method, by using the estimated battery life time or by using the invalid connection state, can detect and correct most cases of incorrect in/out statuses generated by the conventional approach. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks
Sensors 2010, 10(4), 2752-2769; doi:10.3390/s100402752
Received: 27 January 2010 / Revised: 12 February 2010 / Accepted: 15 March 2010 / Published: 26 March 2010
Cited by 4 | PDF Full-text (188 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time
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This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme. Full article
Open AccessArticle Acquiring Authentic Data in Unattended Wireless Sensor Networks
Sensors 2010, 10(4), 2770-2792; doi:10.3390/s100402770
Received: 10 February 2010 / Revised: 25 February 2010 / Accepted: 16 March 2010 / Published: 26 March 2010
Cited by 9 | PDF Full-text (830 KB) | HTML Full-text | XML Full-text
Abstract
An Unattended Wireless Sensor Network (UWSN) can be used in many applications to collect valuable data. Nevertheless, due to the unattended nature, the sensors could be compromised and the sensor readings would be maliciously altered so that the sink accepts the falsified sensor
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An Unattended Wireless Sensor Network (UWSN) can be used in many applications to collect valuable data. Nevertheless, due to the unattended nature, the sensors could be compromised and the sensor readings would be maliciously altered so that the sink accepts the falsified sensor readings. Unfortunately, few attentions have been given to this authentication problem. Moreover, existing methods suffer from different kinds of DoS attacks such as Path-Based DoS (PDoS) and False Endorsement-based DoS (FEDoS) attacks. In this paper, a scheme, called AAD, is proposed to Acquire Authentic Data in UWSNs. We exploit the collaboration among sensors to address the authentication problem. With the proper design of the collaboration mechanism, AAD has superior resilience against sensor compromises, PDoS attack, and FEDoS attack. In addition, compared with prior works, AAD also has relatively low energy consumption. In particular, according to our simulation, in a network with 1, 000 sensors, the energy consumed by AAD is lower than 30% of that consumed by the existing method, ExCo. The analysis and simulation are also conducted to demonstrate the superiority of the proposed AAD scheme over the existing methods. Full article
Open AccessArticle DRDT: Distributed and Reliable Data Transmission with Cooperative Nodes for LossyWireless Sensor Networks
Sensors 2010, 10(4), 2793-2811; doi:10.3390/s100402793
Received: 11 February 2010 / Revised: 10 March 2010 / Accepted: 16 March 2010 / Published: 29 March 2010
Cited by 9 | PDF Full-text (1881 KB) | HTML Full-text | XML Full-text
Abstract
Recent studies have shown that in realistic wireless sensor network environments links are extremely unreliable. To recover from corrupted packets, most routing schemes with an assumption of ideal radio environments use a retransmission mechanism, which may cause unnecessary retransmissions. Therefore, guaranteeing energy-efficient reliable
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Recent studies have shown that in realistic wireless sensor network environments links are extremely unreliable. To recover from corrupted packets, most routing schemes with an assumption of ideal radio environments use a retransmission mechanism, which may cause unnecessary retransmissions. Therefore, guaranteeing energy-efficient reliable data transmission is a fundamental routing issue in wireless sensor networks. However, it is not encouraged to propose a new reliable routing scheme in the sense that every existing routing scheme cannot be replaced with the new one. This paper proposes a Distributed and Reliable Data Transmission (DRDT) scheme with a goal to efficiently guarantee reliable data transmission. In particular, this is based on a pluggable modular approach so that it can be extended to existing routing schemes. DRDT offers reliable data transmission using neighbor nodes, i.e., helper nodes. A helper node is selected among the neighbor nodes of the receiver node which overhear the data packet in a distributed manner. DRDT effectively reduces the number of retransmissions by delegating the retransmission task from the sender node to the helper node that has higher link quality to the receiver node when the data packet reception fails due to the low link quality between the sender and the receiver nodes. Comprehensive simulation results show that DRDT improves end-to-end transmission cost by up to about 45% and reduces its delay by about 40% compared to existing schemes. Full article
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Open AccessArticle Development of a Chemiresistor Sensor Based on Polymers-Dye Blend for Detection of Ethanol Vapor
Sensors 2010, 10(4), 2812-2820; doi:10.3390/s100402812
Received: 15 January 2010 / Revised: 3 February 2010 / Accepted: 1 March 2010 / Published: 29 March 2010
Cited by 10 | PDF Full-text (336 KB) | HTML Full-text | XML Full-text
Abstract
The conductive blend of the poly (3,4-ethylene dioxythiophene) and polystyrene sulfonated acid (PEDOT-PSS) polymers were doped with Methyl Red (MR) dye in the acid form and were used as the basis for a chemiresistor sensor for detection of ethanol vapor. This Au│Polymers-dye blend│Au
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The conductive blend of the poly (3,4-ethylene dioxythiophene) and polystyrene sulfonated acid (PEDOT-PSS) polymers were doped with Methyl Red (MR) dye in the acid form and were used as the basis for a chemiresistor sensor for detection of ethanol vapor. This Au│Polymers-dye blend│Au device was manufactured by chemical vapor deposition and spin-coating, the first for deposition of the metal electrodes onto a glass substrate, and the second for preparation of the organic thin film forming ~1.0 mm2 of active area. The results obtained are the following: (i) electrical resistance dependence with atmospheres containing ethanol vapor carried by nitrogen gas and humidity; (ii) sensitivity at 1.15 for limit detection of 26.25 ppm analyte and an operating temperature of 25 °C; and (iii) the sensing process is quickly reversible and shows very a low power consumption of 20 μW. The thin film morphology of ~200 nm thickness was analyzed by Atomic Force Microscopy (AFM), where it was observed to have a peculiarly granulometric surface favorable to adsorption. This work indicates that PEDOT-PSS doped with MR dye to compose blend film shows good performance like resistive sensor. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Performance Analysis and Improvement of WPAN MAC for Home Networks
Sensors 2010, 10(4), 2821-2842; doi:10.3390/s100402821
Received: 18 January 2010 / Revised: 3 February 2010 / Accepted: 18 March 2010 / Published: 29 March 2010
Cited by 1 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed to coordinate the access to the wireless medium among the competing devices, especially for
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The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed to coordinate the access to the wireless medium among the competing devices, especially for short range and high data rate applications in home networks. In this paper we use analytical modeling to study the performance analysis of WPAN (IEEE 802.15.3) MAC in terms of throughput, efficient bandwidth utilization, and delay with various ACK policies under error channel condition. This allows us to introduce a K-Dly-ACK-AGG policy, payload size adjustment mechanism, and Improved Backoff algorithm to improve the performance of the WPAN MAC. Performance evaluation results demonstrate the impact of our improvements on network capacity. Moreover, these results can be very useful to WPAN application designers and protocol architects to easily and correctly implement WPAN for home networking. Full article
Open AccessCommunication Active Ground Optical Remote Sensing for Improved Monitoring of Seedling Stress in Nurseries
Sensors 2010, 10(4), 2843-2850; doi:10.3390/s100402843
Received: 5 February 2010 / Revised: 11 March 2010 / Accepted: 24 March 2010 / Published: 29 March 2010
Cited by 20 | PDF Full-text (247 KB) | HTML Full-text | XML Full-text
Abstract
Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and do not require
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Active ground optical remote sensing (AGORS) devices mounted on overhead irrigation booms could help to improve seedling quality by autonomously monitoring seedling stress. In contrast to traditionally used passive optical sensors, AGORS devices operate independently of ambient light conditions and do not require spectral reference readings. Besides measuring red (590–670 nm) and near-infrared (>760 nm) reflectance AGORS devices have recently become available that also measure red-edge (730 nm) reflectance. We tested the hypothesis that the additional availability of red-edge reflectance information would improve AGORS of plant stress induced chlorophyll breakdown in Scots pine (Pinus sylvestris). Our results showed that the availability of red-edge reflectance information improved AGORS estimates of stress induced variation in chlorophyll concentration (r2 > 0.73, RMSE < 1.69) when compared to those without (r2 = 0.57, RMSE = 2.11). Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Galvanostatic Entrapment of Penicillinase into Polytyramine Films and its Utilization for the Potentiometric Determination of Penicillin
Sensors 2010, 10(4), 2851-2868; doi:10.3390/s100402851
Received: 2 January 2010 / Revised: 16 March 2010 / Accepted: 24 March 2010 / Published: 29 March 2010
Cited by 3 | PDF Full-text (740 KB) | HTML Full-text | XML Full-text
Abstract
A sensitive and reliable potentiometric biosensor for determination of penicillin has been developed by exploiting the self-limiting growth of the non-conducting polymer, polytyramine. Optimum polytyramine-penicillinase (PTy-PNCnase) films for potentiometric detection of penicillin were accomplished with monomer solutions which contained 0.03 M tyramine, 37
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A sensitive and reliable potentiometric biosensor for determination of penicillin has been developed by exploiting the self-limiting growth of the non-conducting polymer, polytyramine. Optimum polytyramine-penicillinase (PTy-PNCnase) films for potentiometric detection of penicillin were accomplished with monomer solutions which contained 0.03 M tyramine, 37 U/mL penicillinase, 0.01 M KNO3,and 3 mM penicillin with an applied current density of 0.8 mA/cm2 and an electropolymerisation time of 40 seconds. The potentiometric biosensor gave a linear concentration range of 3–283 µM for penicillin and achieved a minimum detectable concentration of 0.3 µM. The biosensor was successfully utilized for the detection of Amoxycillin and gave an average percentage recovery of 102 ± 6%. Satisfactory recoveries of penicillin G were also achieved in milk samples with the potentiometric biosensor when concentrations are ≥20 ppm. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Discriminant Analysis of Raman Spectra for Body Fluid Identification for Forensic Purposes
Sensors 2010, 10(4), 2869-2884; doi:10.3390/s100402869
Received: 11 February 2010 / Revised: 13 March 2010 / Accepted: 23 March 2010 / Published: 29 March 2010
Cited by 52 | PDF Full-text (880 KB) | HTML Full-text | XML Full-text
Abstract
Detection and identification of blood, semen and saliva stains, the most common body fluids encountered at a crime scene, are very important aspects of forensic science today. This study targets the development of a nondestructive, confirmatory method for body fluid identification based on
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Detection and identification of blood, semen and saliva stains, the most common body fluids encountered at a crime scene, are very important aspects of forensic science today. This study targets the development of a nondestructive, confirmatory method for body fluid identification based on Raman spectroscopy coupled with advanced statistical analysis. Dry traces of blood, semen and saliva obtained from multiple donors were probed using a confocal Raman microscope with a 785-nm excitation wavelength under controlled laboratory conditions. Results demonstrated the capability of Raman spectroscopy to identify an unknown substance to be semen, blood or saliva with high confidence. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle Real-Time Occlusion Handling in Augmented Reality Based on an Object Tracking Approach
Sensors 2010, 10(4), 2885-2900; doi:10.3390/s100402885
Received: 28 January 2010 / Revised: 2 March 2010 / Accepted: 14 March 2010 / Published: 29 March 2010
Cited by 16 | PDF Full-text (435 KB) | HTML Full-text | XML Full-text
Abstract
To produce a realistic augmentation in Augmented Reality, the correct relative positions of real objects and virtual objects are very important. In this paper, we propose a novel real-time occlusion handling method based on an object tracking approach. Our method is divided into
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To produce a realistic augmentation in Augmented Reality, the correct relative positions of real objects and virtual objects are very important. In this paper, we propose a novel real-time occlusion handling method based on an object tracking approach. Our method is divided into three steps: selection of the occluding object, object tracking and occlusion handling. The user selects the occluding object using an interactive segmentation method. The contour of the selected object is then tracked in the subsequent frames in real-time. In the occlusion handling step, all the pixels on the tracked object are redrawn on the unprocessed augmented image to produce a new synthesized image in which the relative position between the real and virtual object is correct. The proposed method has several advantages. First, it is robust and stable, since it remains effective when the camera is moved through large changes of viewing angles and volumes or when the object and the background have similar colors. Second, it is fast, since the real object can be tracked in real-time. Last, a smoothing technique provides seamless merging between the augmented and virtual object. Several experiments are provided to validate the performance of the proposed method. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Investigation on Reliability and Scalability of an FBG-Based Hierarchical AOFSN
Sensors 2010, 10(4), 2901-2918; doi:10.3390/s100402901
Received: 1 February 2010 / Revised: 25 February 2010 / Accepted: 10 March 2010 / Published: 29 March 2010
Cited by 6 | PDF Full-text (498 KB) | HTML Full-text | XML Full-text
Abstract
The reliability and scalability of large-scale based optical fiber sensor networks (AOFSN) are considered in this paper. The AOFSN network consists of three-level hierarchical sensor network architectures. The first two levels consist of active interrogation and remote nodes (RNs) and the third level,
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The reliability and scalability of large-scale based optical fiber sensor networks (AOFSN) are considered in this paper. The AOFSN network consists of three-level hierarchical sensor network architectures. The first two levels consist of active interrogation and remote nodes (RNs) and the third level, called the sensor subnet (SSN), consists of passive Fiber Bragg Gratings (FBGs) and a few switches. The switch architectures in the RN and various SSNs to improve the reliability and scalability of AOFSN are studied. Two SSNs with a regular topology are proposed to support simple routing and scalability in AOFSN: square-based sensor cells (SSC) and pentagon-based sensor cells (PSC). The reliability and scalability are evaluated in terms of the available sensing coverage in the case of one or multiple link failures. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Adaptive-Compression Based Congestion Control Technique for Wireless Sensor Networks
Sensors 2010, 10(4), 2919-2945; doi:10.3390/s100402919
Received: 27 January 2010 / Revised: 22 February 2010 / Accepted: 16 March 2010 / Published: 29 March 2010
Cited by 23 | PDF Full-text (1186 KB) | HTML Full-text | XML Full-text
Abstract
Congestion in a wireless sensor network causes an increase in the amount of data loss and delays in data transmission. In this paper, we propose a new congestion control technique (ACT, Adaptive Compression-based congestion control Technique) based on an adaptive compression scheme for
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Congestion in a wireless sensor network causes an increase in the amount of data loss and delays in data transmission. In this paper, we propose a new congestion control technique (ACT, Adaptive Compression-based congestion control Technique) based on an adaptive compression scheme for packet reduction in case of congestion. The compression techniques used in the ACT are Discrete Wavelet Transform (DWT), Adaptive Differential Pulse Code Modulation (ADPCM), and Run-Length Coding (RLC). The ACT first transforms the data from the time domain to the frequency domain, reduces the range of data by using ADPCM, and then reduces the number of packets with the help of RLC before transferring the data to the source node. It introduces the DWT for priority-based congestion control because the DWT classifies the data into four groups with different frequencies. The ACT assigns priorities to these data groups in an inverse proportion to the respective frequencies of the data groups and defines the quantization step size of ADPCM in an inverse proportion to the priorities. RLC generates a smaller number of packets for a data group with a low priority. In the relaying node, the ACT reduces the amount of packets by increasing the quantization step size of ADPCM in case of congestion. Moreover, in order to facilitate the back pressure, the queue is controlled adaptively according to the congestion state. We experimentally demonstrate that the ACT increases the network efficiency and guarantees fairness to sensor nodes, as compared with the existing methods. Moreover, it exhibits a very high ratio of the available data in the sink. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems
Sensors 2010, 10(4), 2946-2956; doi:10.3390/s100402946
Received: 1 January 2010 / Revised: 23 February 2010 / Accepted: 9 March 2010 / Published: 29 March 2010
Cited by 20 | PDF Full-text (1252 KB) | HTML Full-text | XML Full-text
Abstract
We have developed a hydraulic displacement amplification mechanism (HDAM) and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS) membranes. The geometry with input and
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We have developed a hydraulic displacement amplification mechanism (HDAM) and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS) membranes. The geometry with input and output surfaces having different cross-sectional areas creates amplification. By combining the HDAM with micro-actuators, we can amplify the input displacement generated by the actuators, which is useful for applications requiring large deformation, such as tactile displays. We achieved a mechanism offering up to 18-fold displacement amplification for static actuation and 12-fold for 55 Hz dynamic actuation. Full article
(This article belongs to the Special Issue Advances in Actuators)
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Open AccessArticle Development of an Indoor Location Based Service Test Bed and Geographic Information System with a Wireless Sensor Network
Sensors 2010, 10(4), 2957-2974; doi:10.3390/s100402957
Received: 28 January 2010 / Revised: 2 March 2010 / Accepted: 11 March 2010 / Published: 30 March 2010
Cited by 13 | PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
In order to provide the seamless navigation and positioning services for indoor environments, an indoor location based service (LBS) test bed is developed to integrate the indoor positioning system and the indoor three-dimensional (3D) geographic information system (GIS). A wireless sensor network (WSN)
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In order to provide the seamless navigation and positioning services for indoor environments, an indoor location based service (LBS) test bed is developed to integrate the indoor positioning system and the indoor three-dimensional (3D) geographic information system (GIS). A wireless sensor network (WSN) is used in the developed indoor positioning system. Considering the power consumption, in this paper the ZigBee radio is used as the wireless protocol, and the received signal strength (RSS) fingerprinting positioning method is applied as the primary indoor positioning algorithm. The matching processes of the user location include the nearest neighbor (NN) algorithm, the K-weighted nearest neighbors (KWNN) algorithm, and the probabilistic approach. To enhance the positioning accuracy for the dynamic user, the particle filter is used to improve the positioning performance. As part of this research, a 3D indoor GIS is developed to be used with the indoor positioning system. This involved using the computer-aided design (CAD) software and the virtual reality markup language (VRML) to implement a prototype indoor LBS test bed. Thus, a rapid and practical procedure for constructing a 3D indoor GIS is proposed, and this GIS is easy to update and maintenance for users. The building of the Department of Aeronautics and Astronautics at National Cheng Kung University in Taiwan is used as an example to assess the performance of various algorithms for the indoor positioning system. Full article
Open AccessArticle Optical Flow in a Smart Sensor Based on Hybrid Analog-Digital Architecture
Sensors 2010, 10(4), 2975-2994; doi:10.3390/s100402975
Received: 20 January 2010 / Revised: 5 March 2010 / Accepted: 17 March 2010 / Published: 30 March 2010
Cited by 4 | PDF Full-text (1002 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of this study is to develop a motion sensor (delivering optical flow estimations) using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single
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The purpose of this study is to develop a motion sensor (delivering optical flow estimations) using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single device as a SoC (System-on-a-Chip). Optical flow is the 2-D projection into the camera plane of the 3-D motion information presented at the world scenario. This motion representation is widespread well-known and applied in the science community to solve a wide variety of problems. Most applications based on motion estimation require work in real-time; hence, this restriction must be taken into account. In this paper, we show an efficient approach to estimate the motion velocity vectors with an architecture based on a focal plane processor combined on-chip with a 32 bits NIOS II processor. Our approach relies on the simplification of the original optical flow model and its efficient implementation in a platform that combines an analog (focal-plane) and digital (NIOS II) processor. The system is fully functional and is organized in different stages where the early processing (focal plane) stage is mainly focus to pre-process the input image stream to reduce the computational cost in the post-processing (NIOS II) stage. We present the employed co-design techniques and analyze this novel architecture. We evaluate the system’s performance and accuracy with respect to the different proposed approaches described in the literature. We also discuss the advantages of the proposed approach as well as the degree of efficiency which can be obtained from the focal plane processing capabilities of the system. The final outcome is a low cost smart sensor for optical flow computation with real-time performance and reduced power consumption that can be used for very diverse application domains. Full article
(This article belongs to the Special Issue Motion Detectors)
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Open AccessArticle Implementation and Evaluation of the WADGPS System in the Taipei Flight Information Region
Sensors 2010, 10(4), 2995-3022; doi:10.3390/s100402995
Received: 11 January 2010 / Revised: 9 February 2010 / Accepted: 14 March 2010 / Published: 30 March 2010
Cited by 4 | PDF Full-text (3997 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the implementation of the Wide Area Differential Global Positioning System (WADGPS) system in order to evaluate the operational performance of a satellite based aviation navigation system within Taipei Flight Information Region (FIR). The main objective of the WADGPS is to
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This paper describes the implementation of the Wide Area Differential Global Positioning System (WADGPS) system in order to evaluate the operational performance of a satellite based aviation navigation system within Taipei Flight Information Region (FIR). The main objective of the WADGPS is to provide real time integrity information regarding the use of GPS for civil aviation applications. This paper uses the e-GPS observation stations operated by the Taiwan Ministry of Interior (MOI) as the WADGPS reference stations to collect the L1-L2 dual-frequency GPS measurements. A WADGPS master station is also implemented to process all GPS measurements sent from each reference station, and then generate the vector corrections. These vector corrections consist of the satellite ephemeris and clock errors, and a grid of ionospheric delays. The data stream also includes confidence bounds for the corrections and “Use/Do Not Use” messages to provide integrity. These messages are then passed to the WADGPS user through the Internet. This paper discusses the WADGPS system architecture and the system performance analysis. A five-day operation performance in Taipei Flight Information Region (FIR) is presented in this paper. The results show that the WADGPS can improve the accuracy performance of GPS positioning and fulfill the integrity performance required by Non-Precision Approach (NPA) defined by the International Civil Aviation Organization (ICAO). Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Data Centric Storage Technologies: Analysis and Enhancement
Sensors 2010, 10(4), 3023-3056; doi:10.3390/s100403023
Received: 28 January 2010 / Revised: 20 February 2010 / Accepted: 13 March 2010 / Published: 30 March 2010
Cited by 9 | PDF Full-text (908 KB) | HTML Full-text | XML Full-text
Abstract
This paper surveys the most relevant works of Data Centric Storage (DCS) for Wireless Sensor Networks. DCS is a research area that covers data dissemination and storage inside an ad-hoc sensor network. In addition, we present a Quadratic Adaptive Replication (QAR) scheme for
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This paper surveys the most relevant works of Data Centric Storage (DCS) for Wireless Sensor Networks. DCS is a research area that covers data dissemination and storage inside an ad-hoc sensor network. In addition, we present a Quadratic Adaptive Replication (QAR) scheme for DCS, which is a more adaptive multi-replication DCS system and outperforms previous proposals in the literature by reducing the overall network traffic that has a direct impact on energy consumption. Finally, we discuss the open research challenges for DCS. Full article
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Open AccessArticle The Assessment for Sensitivity of a NO2 Gas Sensor with ZnGa2O4/ZnO Core-Shell Nanowires—a Novel Approach
Sensors 2010, 10(4), 3057-3072; doi:10.3390/s100403057
Received: 15 March 2010 / Revised: 23 March 2010 / Accepted: 24 March 2010 / Published: 30 March 2010
Cited by 19 | PDF Full-text (698 KB) | HTML Full-text | XML Full-text
Abstract
The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on
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The application of novel core-shell nanowires composed of ZnGa2O4/ZnO to improve the sensitivity of NO2 gas sensors is demonstrated in this study. The growth of ZnGa2O4/ZnO core-shell nanowires is performed by reactive evaporation on patterned ZnO:Ga/SiO2/Si templates at 600 °C. This is to form the homogeneous structure of the sensors investigated in this report to assess their sensitivity in terms of NO2 detection. These novel NO2 gas sensors were evaluated at working temperatures of 25 °C and at 250 °C, respectively. The result reveals the ZnGa2O4/ZnO core-shell nanowires present a good linear relationship (R2 > 0.99) between sensitivity and NO2 concentration at both working temperatures. These core-shell nanowire sensors also possess the highest response (<90 s) and recovery (<120 s) values with greater repeatability seen for NO2 sensors at room temperature, unlike traditional sensors that only work effectively at much higher temperatures. The data in this study indicates the newly-developed ZnGa2O4/ZnO core-shell nanowire based sensors are highly promising for industrial applications. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Evaluation of Performance and Uncertainty of Infrared Tympanic Thermometers
Sensors 2010, 10(4), 3073-3089; doi:10.3390/s100403073
Received: 21 February 2010 / Revised: 13 March 2010 / Accepted: 23 March 2010 / Published: 31 March 2010
Cited by 6 | PDF Full-text (260 KB) | HTML Full-text | XML Full-text
Abstract
Infrared tympanic thermometers (ITTs) are easy to use and have a quick response time. They are widely used for temperature measurement of the human body. The accuracy and uncertainty of measurement is the importance performance indicator for these meters. The performance of two
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Infrared tympanic thermometers (ITTs) are easy to use and have a quick response time. They are widely used for temperature measurement of the human body. The accuracy and uncertainty of measurement is the importance performance indicator for these meters. The performance of two infrared tympanic thermometers, Braun THT-3020 and OMRON MC-510, were evaluated in this study. The cell of a temperature calibrator was modified to serve as the standard temperature of the blackbody. The errors of measurement for the two meters were reduced by the calibration equation. The predictive values could meet the requirements of the ASTM standard. The sources of uncertainty include the standard deviations of replication at fixed temperature or the predicted values of calibration equation, reference standard values and resolution. The uncertainty analysis shows that the uncertainty of calibration equation is the main source for combined uncertainty. Ambient temperature did not have the significant effects on the measured performance. The calibration equations could improve the accuracy of ITTs. However, these equations did not improve the uncertainty of ITTs. Full article
Open AccessArticle Design and Instrumentation of a Measurement and Calibration System for an Acoustic Telemetry System
Sensors 2010, 10(4), 3090-3099; doi:10.3390/s100403090
Received: 31 January 2010 / Revised: 20 February 2010 / Accepted: 23 March 2010 / Published: 31 March 2010
Cited by 22 | PDF Full-text (332 KB) | HTML Full-text | XML Full-text
Abstract
The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is used primarily for evaluating behavior and survival of juvenile salmonids migrating through the
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The Juvenile Salmon Acoustic Telemetry System (JSATS) is an active sensing technology developed by the U.S. Army Corps of Engineers, Portland District, for detecting and tracking small fish. It is used primarily for evaluating behavior and survival of juvenile salmonids migrating through the Federal Columbia River Power System to the Pacific Ocean. It provides critical data for salmon protection and development of more “fish-friendly” hydroelectric facilities. The objective of this study was to design and build a Measurement and Calibration System (MCS) for evaluating the JSATS components, because the JSATS requires comprehensive acceptance and performance testing in a controlled environment before it is deployed in the field. The MCS consists of a reference transducer, a water test tank lined with anechoic material, a motion control unit, a reference receiver, a signal conditioner and amplifier unit, a data acquisition board, MATLAB control and analysis interface, and a computer. The fully integrated MCS has been evaluated successfully at various simulated distances and using different encoded signals at frequencies within the bandwidth of the JSATS transmitter. The MCS provides accurate acoustic mapping capability in a controlled environment and automates the process that allows real-time measurements and evaluation of the piezoelectric transducers, sensors, or the acoustic fields. The MCS has been in use since 2009 for acceptance and performance testing of, and further improvements to, the JSATS. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Energy-aware Scheduling of Surveillance in Wireless Multimedia Sensor Networks
Sensors 2010, 10(4), 3100-3125; doi:10.3390/s100403100
Received: 3 February 2010 / Revised: 8 March 2010 / Accepted: 24 March 2010 / Published: 31 March 2010
Cited by 6 | PDF Full-text (362 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks involve a large number of sensor nodes with limited energy supply, which impacts the behavior of their application. In wireless multimedia sensor networks, sensor nodes are equipped with audio and visual information collection modules. Multimedia contents are ubiquitously retrieved in
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Wireless sensor networks involve a large number of sensor nodes with limited energy supply, which impacts the behavior of their application. In wireless multimedia sensor networks, sensor nodes are equipped with audio and visual information collection modules. Multimedia contents are ubiquitously retrieved in surveillance applications. To solve the energy problems during target surveillance with wireless multimedia sensor networks, an energy-aware sensor scheduling method is proposed in this paper. Sensor nodes which acquire acoustic signals are deployed randomly in the sensing fields. Target localization is based on the signal energy feature provided by multiple sensor nodes, employing particle swarm optimization (PSO). During the target surveillance procedure, sensor nodes are adaptively grouped in a totally distributed manner. Specially, the target motion information is extracted by a forecasting algorithm, which is based on the hidden Markov model (HMM). The forecasting results are utilized to awaken sensor node in the vicinity of future target position. According to the two properties, signal energy feature and residual energy, the sensor nodes decide whether to participate in target detection separately with a fuzzy control approach. Meanwhile, the local routing scheme of data transmission towards the observer is discussed. Experimental results demonstrate the efficiency of energy-aware scheduling of surveillance in wireless multimedia sensor network, where significant energy saving is achieved by the sensor awakening approach and data transmission paths are calculated with low computational complexity. Full article
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Open AccessArticle A Method for Clustering and Cooperation in Wireless Multimedia Sensor Networks
Sensors 2010, 10(4), 3145-3169; doi:10.3390/s100403145
Received: 21 January 2010 / Revised: 23 February 2010 / Accepted: 12 March 2010 / Published: 31 March 2010
Cited by 11 | PDF Full-text (378 KB) | HTML Full-text | XML Full-text
Abstract
Wireless multimedia sensor nodes sense areas that are uncorrelated to the areas covered by radio neighbouring sensors. Thus, node clustering for coordinating multimedia sensing and processing cannot be based on classical sensor clustering algorithms. This paper presents a clustering mechanism for Wireless Multimedia
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Wireless multimedia sensor nodes sense areas that are uncorrelated to the areas covered by radio neighbouring sensors. Thus, node clustering for coordinating multimedia sensing and processing cannot be based on classical sensor clustering algorithms. This paper presents a clustering mechanism for Wireless Multimedia Sensor Networks (WMSNs) based on overlapped Field of View (FoV) areas. Overlapping FoVs in dense networks cause the wasting of power due to redundant area sensing. The main aim of the proposed clustering method is energy conservation and network lifetime prolongation. This objective is achieved through coordination of nodes belonging to the same cluster to perform assigned tasks in a cooperative manner avoiding redundant sensing or processing. A paradigm in this concept, a cooperative scheduling scheme for object detection, is presented based on the proposed clustering method. Full article
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Open AccessArticle Novel Anti Co-Channel Interference Scheme for Sensor Networks
Sensors 2010, 10(4), 3170-3179; doi:10.3390/s100403170
Received: 5 January 2010 / Revised: 8 March 2010 / Accepted: 15 March 2010 / Published: 31 March 2010
Cited by 6 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
With improvement of the automation level, wireless sensors are widely used, but various kinds of interference lead to problems in the application. In order to deal with co-channel interference, a throughput efficient scheme based on Extended Binary Phase Shift Keying (EBPSK) modulation is
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With improvement of the automation level, wireless sensors are widely used, but various kinds of interference lead to problems in the application. In order to deal with co-channel interference, a throughput efficient scheme based on Extended Binary Phase Shift Keying (EBPSK) modulation is introduced in physical layer. On this basis, the corresponding transmission scheme and the important impacting filter are presented. Effects of co-channel interference on the EBPSK waveform in different cases are analyzed. Simulation results illustrate the excellent anti-interference performance of the EBPSK system itself, when the initial phase of the co-channel interference is small. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A New Myohaptic Instrument to Assess Wrist Motion Dynamically
Sensors 2010, 10(4), 3180-3194; doi:10.3390/s100403180
Received: 19 January 2010 / Revised: 11 February 2010 / Accepted: 24 March 2010 / Published: 1 April 2010
Cited by 6 | PDF Full-text (534 KB) | HTML Full-text | XML Full-text
Abstract
The pathophysiological assessment of joint properties and voluntary motion in neurological patients remains a challenge. This is typically the case in cerebellar patients, who exhibit dysmetric movements due to the dysfunction of cerebellar circuitry. Several tools have been developed, but so far most
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The pathophysiological assessment of joint properties and voluntary motion in neurological patients remains a challenge. This is typically the case in cerebellar patients, who exhibit dysmetric movements due to the dysfunction of cerebellar circuitry. Several tools have been developed, but so far most of these tools have remained confined to laboratories, with a lack of standardization. We report on a new device which combines the use of electromyographic (EMG) sensors with haptic technology for the dynamic investigation of wrist properties. The instrument is composed of a drivetrain, a haptic controller and a signal acquisition unit. Angular accuracy is 0.00611 rad, nominal torque is 6 N·m, maximal rotation velocity is 34.907 rad/sec, with a range of motion of –1.0472 to +1.0472 rad. The inertia of the motor and handgrip is 0.004 kg·m². This is the first standardized myohaptic instrument allowing the dynamic characterization of wrist properties, including under the condition of artificial damping. We show that cerebellar patients are unable to adapt EMG activities when faced with an increase in damping while performing fast reversal movements. The instrument allows the extraction of an electrophysiological signature of a cerebellar deficit. Full article
Open AccessArticle Evaluation of Tunable Data Compression in Energy-Aware Wireless Sensor Networks
Sensors 2010, 10(4), 3195-3217; doi:10.3390/s100403195
Received: 30 November 2009 / Revised: 26 January 2010 / Accepted: 16 March 2010 / Published: 1 April 2010
Cited by 2 | PDF Full-text (232 KB) | HTML Full-text | XML Full-text
Abstract
Energy is an important consideration in wireless sensor networks. In the current compression evaluations, traditional indices are still used, while energy efficiency is probably neglected. Moreover, various evaluation biases significantly affect the final results. All these factors lead to a subjective evaluation. In
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Energy is an important consideration in wireless sensor networks. In the current compression evaluations, traditional indices are still used, while energy efficiency is probably neglected. Moreover, various evaluation biases significantly affect the final results. All these factors lead to a subjective evaluation. In this paper, a new criterion is proposed and a series of tunable compression algorithms are reevaluated. The results show that the new criterion makes the evaluation more objective. Additionally it indicates the situations when compression is unnecessary. A new adaptive compression arbitration system is proposed based on the evaluation results, which improves the performance of compression algorithms. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Wireless Health Data Exchange for Home Healthcare Monitoring Systems
Sensors 2010, 10(4), 3243-3260; doi:10.3390/s100403243
Received: 28 January 2010 / Revised: 4 March 2010 / Accepted: 15 March 2010 / Published: 1 April 2010
Cited by 19 | PDF Full-text (817 KB) | HTML Full-text | XML Full-text
Abstract
Ubiquitous home healthcare systems have been playing an increasingly significant role in the treatment and management of chronic diseases, such as diabetes and hypertension, but progress has been hampered by the lack of standardization in the exchange of medical health care information. In
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Ubiquitous home healthcare systems have been playing an increasingly significant role in the treatment and management of chronic diseases, such as diabetes and hypertension, but progress has been hampered by the lack of standardization in the exchange of medical health care information. In an effort to establish standardization, this paper proposes a home healthcare monitoring system data exchange scheme between the HL7 standard and the IEEE1451 standard. IEEE1451 is a standard for special sensor networks, such as industrial control and smart homes, and defines a suite of interfaces that communicate among heterogeneous networks. HL7 is the standard for medical information exchange among medical organizations and medical personnel. While it provides a flexible data exchange in health care domains, it does not provide for data exchange with sensors. Thus, it is necessary to develop a data exchange schema to convert data between the HL7 and the IEEE1451 standard. This paper proposes a schema that can exchange data between HL7 devices and the monitoring device, and conforms to the IEEE 1451 standard. The experimental results and conclusions of this approach are presented and show the feasibility of the proposed exchange schema. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Multi-Camera Sensor System for 3D Segmentation and Localization of Multiple Mobile Robots
Sensors 2010, 10(4), 3261-3279; doi:10.3390/s100403261
Received: 5 February 2010 / Revised: 23 March 2010 / Accepted: 26 March 2010 / Published: 1 April 2010
Cited by 17 | PDF Full-text (739 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a method for obtaining the motion segmentation and 3D localization of multiple mobile robots in an intelligent space using a multi-camera sensor system. The set of calibrated and synchronized cameras are placed in fixed positions within the environment (intelligent space).
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This paper presents a method for obtaining the motion segmentation and 3D localization of multiple mobile robots in an intelligent space using a multi-camera sensor system. The set of calibrated and synchronized cameras are placed in fixed positions within the environment (intelligent space). The proposed algorithm for motion segmentation and 3D localization is based on the minimization of an objective function. This function includes information from all the cameras, and it does not rely on previous knowledge or invasive landmarks on board the robots. The proposed objective function depends on three groups of variables: the segmentation boundaries, the motion parameters and the depth. For the objective function minimization, we use a greedy iterative algorithm with three steps that, after initialization of segmentation boundaries and depth, are repeated until convergence. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle GFZ Wireless Seismic Array (GFZ-WISE), a Wireless Mesh Network of Seismic Sensors: New Perspectives for Seismic Noise Array Investigations and Site Monitoring
Sensors 2010, 10(4), 3280-3304; doi:10.3390/s100403280
Received: 4 February 2010 / Revised: 12 March 2010 / Accepted: 15 March 2010 / Published: 1 April 2010
Cited by 19 | PDF Full-text (1506 KB) | HTML Full-text | XML Full-text
Abstract
Over the last few years, the analysis of seismic noise recorded by two dimensional arrays has been confirmed to be capable of deriving the subsoil shear-wave velocity structure down to several hundred meters depth. In fact, using just a few minutes of seismic
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Over the last few years, the analysis of seismic noise recorded by two dimensional arrays has been confirmed to be capable of deriving the subsoil shear-wave velocity structure down to several hundred meters depth. In fact, using just a few minutes of seismic noise recordings and combining this with the well known horizontal-to-vertical method, it has also been shown that it is possible to investigate the average one dimensional velocity structure below an array of stations in urban areas with a sufficient resolution to depths that would be prohibitive with active source array surveys, while in addition reducing the number of boreholes required to be drilled for site-effect analysis. However, the high cost of standard seismological instrumentation limits the number of sensors generally available for two-dimensional array measurements (i.e., of the order of 10), limiting the resolution in the estimated shear-wave velocity profiles. Therefore, new themes in site-effect estimation research by two-dimensional arrays involve the development and application of low-cost instrumentation, which potentially allows the performance of dense-array measurements, and the development of dedicated signal-analysis procedures for rapid and robust estimation of shear-wave velocity profiles. In this work, we present novel low-cost wireless instrumentation for dense two-dimensional ambient seismic noise array measurements that allows the real–time analysis of the surface-wavefield and the rapid estimation of the local shear-wave velocity structure for site response studies. We first introduce the general philosophy of the new system, as well as the hardware and software that forms the novel instrument, which we have tested in laboratory and field studies. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessCommunication Laser Photoacoustic Detection of CO2 in Old Disc Tree-Rings
Sensors 2010, 10(4), 3305-3313; doi:10.3390/s100403305
Received: 29 December 2009 / Revised: 16 February 2010 / Accepted: 6 March 2010 / Published: 4 April 2010
Cited by 7 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
A homemade CO2–laser photoacoustic spectrometer has been used for monitoring CO2 in gas samples extracted under vacuum from the wood of old spruce disc tree-rings for a ~60 year series. The experimental results show that (1) the CO2 concentration
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A homemade CO2–laser photoacoustic spectrometer has been used for monitoring CO2 in gas samples extracted under vacuum from the wood of old spruce disc tree-rings for a ~60 year series. The experimental results show that (1) the CO2 concentration exhibits annual trends correlated with an increase in atmospheric CO2 in a number of cases; (2) at the time when the annual CO2 trend changes from positive to negative, the annual tree-ring stable carbon isotope ratios (δ13C) of CO2 change as well; (3) the disc tree-ring widths are observed to decrease in most cases where the annual CO2 increased; (4) simultaneously with the annual CO2 variation, annual H2O distribution was detected in gas samples of the wood tree-rings of one spruce disc. The observed patterns of the annual CO2 distribution in the disc tree-rings are assumed to be the evidence of the impact of the atmospheric CO2 increase. In other words, a change in the concentration gradient between the stem and the atmospheric CO2 may lead to a gradual CO2 accumulation in the stem because of a decrease in the diffusion rate and to a change in the tree parameters. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle A FDR Sensor for Measuring Complex Soil Dielectric Permittivity in the 10–500 MHz Frequency Range
Sensors 2010, 10(4), 3314-3329; doi:10.3390/s100403314
Received: 3 February 2010 / Revised: 5 March 2010 / Accepted: 19 March 2010 / Published: 5 April 2010
Cited by 40 | PDF Full-text (1704 KB) | HTML Full-text | XML Full-text
Abstract
Mechanical details as well as electrical models of FDR (frequency domain reflectometry) sensors for the measurement of the complex dielectric permittivity of porous materials are presented. The sensors are formed from two stainless steel parallel waveguides of various lengths. Using the data from
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Mechanical details as well as electrical models of FDR (frequency domain reflectometry) sensors for the measurement of the complex dielectric permittivity of porous materials are presented. The sensors are formed from two stainless steel parallel waveguides of various lengths. Using the data from VNA (vector network analyzer) with the connected FDR sensor and selected models of the applied sensor it was possible obtain the frequency spectrum of dielectric permittivity from 10 to 500 MHz of reference liquids and soil samples of various moisture and salinity. The performance of the analyzed sensors were compared with TDR (time domain reflectometry) ones of similar mechanical construction. Full article
Open AccessArticle Optimal Filters with Multiple Packet Losses and its Application in Wireless Sensor Networks
Sensors 2010, 10(4), 3330-3350; doi:10.3390/s100403330
Received: 28 January 2010 / Revised: 16 March 2010 / Accepted: 25 March 2010 / Published: 6 April 2010
Cited by 6 | PDF Full-text (343 KB) | HTML Full-text | XML Full-text
Abstract
This paper is concerned with the filtering problem for both discrete-time stochastic linear (DTSL) systems and discrete-time stochastic nonlinear (DTSN) systems. In DTSL systems, an linear optimal filter with multiple packet losses is designed based on the orthogonal principle analysis approach over unreliable
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This paper is concerned with the filtering problem for both discrete-time stochastic linear (DTSL) systems and discrete-time stochastic nonlinear (DTSN) systems. In DTSL systems, an linear optimal filter with multiple packet losses is designed based on the orthogonal principle analysis approach over unreliable wireless sensor networks (WSNs), and the experience result verifies feasibility and effectiveness of the proposed linear filter; in DTSN systems, an extended minimum variance filter with multiple packet losses is derived, and the filter is extended to the nonlinear case by the first order Taylor series approximation, which is successfully applied to unreliable WSNs. An application example is given and the corresponding simulation results show that, compared with extended Kalman filter (EKF), the proposed extended minimum variance filter is feasible and effective in WSNs. Full article
Open AccessArticle Multiplexed Electrochemical Detection of Yersinia Pestis and Staphylococcal Enterotoxin B using an Antibody Microarray
Sensors 2010, 10(4), 3351-3362; doi:10.3390/s100403351
Received: 8 February 2010 / Revised: 28 February 2010 / Accepted: 26 March 2010 / Published: 6 April 2010
Cited by 15 | PDF Full-text (411 KB) | HTML Full-text | XML Full-text
Abstract
The CombiMatrix antibody microarray is a versatile, sensitive detection platform based on the generation and transduction of electrochemical signals following antigen binding to surface antibodies. The sensor chip described herein is comprised of microelectrodes coupled to an adjacent bio-friendly matrix coated with antibodies
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The CombiMatrix antibody microarray is a versatile, sensitive detection platform based on the generation and transduction of electrochemical signals following antigen binding to surface antibodies. The sensor chip described herein is comprised of microelectrodes coupled to an adjacent bio-friendly matrix coated with antibodies to the biological pathogens Yersinia pestis and Bacillus anthracis, and the bacterial toxin staphylococcal enterotoxin B (SEB). Using this system, we were able to detect SEB and inactivated Y. pestis individually as well as in two-plex assays at concentrations as low as 5 pg/mL and 106 CFU/mL, respectively. We also introduce super avidin-biotin system (SABS) as a viable and effective means to enhance assay signal responses and lower detection limits. Together these technologies represent substantial advances in point-of-care and point-of-use detection applications. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle Sensor Fabrication Method for in Situ Temperature and Humidity Monitoring of Light Emitting Diodes
Sensors 2010, 10(4), 3363-3372; doi:10.3390/s100403363
Received: 8 February 2010 / Accepted: 20 March 2010 / Published: 7 April 2010
Cited by 6 | PDF Full-text (1544 KB) | HTML Full-text | XML Full-text
Abstract
In this work micro temperature and humidity sensors are fabricated to measure the junction temperature and humidity of light emitting diodes (LED). The junction temperature is frequently measured using thermal resistance measurement technology. The weakness of this method is that the timing of
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In this work micro temperature and humidity sensors are fabricated to measure the junction temperature and humidity of light emitting diodes (LED). The junction temperature is frequently measured using thermal resistance measurement technology. The weakness of this method is that the timing of data capture is not regulated by any standard. This investigation develops a device that can stably and continually measure temperature and humidity. The device is light-weight and can monitor junction temperature and humidity in real time. Using micro-electro-mechanical systems (MEMS), this study minimizes the size of the micro temperature and humidity sensors, which are constructed on a stainless steel foil substrate (40 μm-thick SS-304). The micro temperature and humidity sensors can be fixed between the LED chip and frame. The sensitivities of the micro temperature and humidity sensors are 0.06 ± 0.005 (Ω/°C) and 0.033 pF/%RH, respectively. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle FPGA-Based Fused Smart-Sensor for Tool-Wear Area Quantitative Estimation in CNC Machine Inserts
Sensors 2010, 10(4), 3373-3388; doi:10.3390/s100403373
Received: 10 February 2010 / Accepted: 29 March 2010 / Published: 7 April 2010
Cited by 20 | PDF Full-text (1084 KB) | HTML Full-text | XML Full-text
Abstract
Manufacturing processes are of great relevance nowadays, when there is a constant claim for better productivity with high quality at low cost. The contribution of this work is the development of a fused smart-sensor, based on FPGA to improve the online quantitative estimation
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Manufacturing processes are of great relevance nowadays, when there is a constant claim for better productivity with high quality at low cost. The contribution of this work is the development of a fused smart-sensor, based on FPGA to improve the online quantitative estimation of flank-wear area in CNC machine inserts from the information provided by two primary sensors: the monitoring current output of a servoamplifier, and a 3-axis accelerometer. Results from experimentation show that the fusion of both parameters makes it possible to obtain three times better accuracy when compared with the accuracy obtained from current and vibration signals, individually used. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Speedy Routing Recovery Protocol for Large Failure Tolerance in Wireless Sensor Networks
Sensors 2010, 10(4), 3389-3410; doi:10.3390/s100403389
Received: 3 March 2010 / Revised: 25 March 2010 / Accepted: 26 March 2010 / Published: 7 April 2010
Cited by 14 | PDF Full-text (2986 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks are expected to play an increasingly important role in data collection in hazardous areas. However, the physical fragility of a sensor node makes reliable routing in hazardous areas a challenging problem. Because several sensor nodes in a hazardous area could
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Wireless sensor networks are expected to play an increasingly important role in data collection in hazardous areas. However, the physical fragility of a sensor node makes reliable routing in hazardous areas a challenging problem. Because several sensor nodes in a hazardous area could be damaged simultaneously, the network should be able to recover routing after node failures over large areas. Many routing protocols take single-node failure recovery into account, but it is difficult for these protocols to recover the routing after large-scale failures. In this paper, we propose a routing protocol, referred to as ARF (Adaptive routing protocol for fast Recovery from large-scale Failure), to recover a network quickly after failures over large areas. ARF detects failures by counting the packet losses from parent nodes, and upon failure detection, it decreases the routing interval to notify the neighbor nodes of the failure. Our experimental results indicate that ARF could provide recovery from large-area failures quickly with less packets and energy consumption than previous protocols. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Information Warfare-Worthy Jamming Attack Detection Mechanism for Wireless Sensor Networks Using a Fuzzy Inference System
Sensors 2010, 10(4), 3444-3479; doi:10.3390/s100403444
Received: 8 February 2010 / Revised: 18 February 2010 / Accepted: 24 March 2010 / Published: 8 April 2010
Cited by 19 | PDF Full-text (687 KB) | HTML Full-text | XML Full-text
Abstract
The proposed mechanism for jamming attack detection for wireless sensor networks is novel in three respects: firstly, it upgrades the jammer to include versatile military jammers; secondly, it graduates from the existing node-centric detection system to the network-centric system making it robust and
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The proposed mechanism for jamming attack detection for wireless sensor networks is novel in three respects: firstly, it upgrades the jammer to include versatile military jammers; secondly, it graduates from the existing node-centric detection system to the network-centric system making it robust and economical at the nodes, and thirdly, it tackles the problem through fuzzy inference system, as the decision regarding intensity of jamming is seldom crisp. The system with its high robustness, ability to grade nodes with jamming indices, and its true-detection rate as high as 99.8%, is worthy of consideration for information warfare defense purposes. Full article
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Open AccessArticle Webcams for Bird Detection and Monitoring: A Demonstration Study
Sensors 2010, 10(4), 3480-3503; doi:10.3390/s100403480
Received: 8 February 2010 / Revised: 17 March 2010 / Accepted: 25 March 2010 / Published: 8 April 2010
Cited by 13 | PDF Full-text (834 KB) | HTML Full-text | XML Full-text
Abstract
Better insights into bird migration can be a tool for assessing the spread of avian borne infections or ecological/climatologic issues reflected in deviating migration patterns. This paper evaluates whether low budget permanent cameras such as webcams can offer a valuable contribution to the
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Better insights into bird migration can be a tool for assessing the spread of avian borne infections or ecological/climatologic issues reflected in deviating migration patterns. This paper evaluates whether low budget permanent cameras such as webcams can offer a valuable contribution to the reporting of migratory birds. An experimental design was set up to study the detection capability using objects of different size, color and velocity. The results of the experiment revealed the minimum size, maximum velocity and contrast of the objects required for detection by a standard webcam. Furthermore, a modular processing scheme was proposed to track and follow migratory birds in webcam recordings. Techniques such as motion detection by background subtraction, stereo vision and lens distortion were combined to form the foundation of the bird tracking algorithm. Additional research to integrate webcam networks, however, is needed and future research should enforce the potential of the processing scheme by exploring and testing alternatives of each individual module or processing step. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)
Sensors 2010, 10(4), 3504-3518; doi:10.3390/s100403504
Received: 20 January 2010 / Revised: 15 March 2010 / Accepted: 23 March 2010 / Published: 8 April 2010
Cited by 7 | PDF Full-text (2309 KB) | HTML Full-text | XML Full-text
Abstract
The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition,
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The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. Full article
(This article belongs to the Section Remote Sensors)
Open AccessArticle Plasma Plume Oscillations Monitoring during Laser Welding of Stainless Steel by Discrete Wavelet Transform Application
Sensors 2010, 10(4), 3549-3561; doi:10.3390/s100403549
Received: 13 January 2010 / Revised: 27 January 2010 / Accepted: 12 March 2010 / Published: 8 April 2010
Cited by 10 | PDF Full-text (808 KB) | HTML Full-text | XML Full-text
Abstract
The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT) has been used to decompose the optical signal into various discrete
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The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT) has been used to decompose the optical signal into various discrete series of sequences over different frequency bands. The results show that changes of the process settings may yield different signal features in the range of frequencies between 200 Hz and 30 kHz. Potential applications of this method to monitor in real time the laser welding processes are also discussed. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Optical Fiber LSPR Biosensor Prepared by Gold Nanoparticle Assembly on Polyelectrolyte Multilayer
Sensors 2010, 10(4), 3585-3596; doi:10.3390/s100403585
Received: 27 January 2010 / Revised: 26 February 2010 / Accepted: 8 March 2010 / Published: 8 April 2010
Cited by 38 | PDF Full-text (773 KB) | HTML Full-text | XML Full-text
Abstract
This article provides a novel method of constructing an optical fiber localized surface plasmon resonance (LSPR) biosensor. A gold nanoparticle (NP) assembled film as the sensing layer was built on the polyelectrolyte (PE) multilayer modified sidewall of an unclad optical fiber. By using
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This article provides a novel method of constructing an optical fiber localized surface plasmon resonance (LSPR) biosensor. A gold nanoparticle (NP) assembled film as the sensing layer was built on the polyelectrolyte (PE) multilayer modified sidewall of an unclad optical fiber. By using a trilayer PE structure, we obtained a monodisperse gold NP assembled film. The preparation procedure for this LSPR sensor is simple and time saving. The optical fiber LSPR sensor has higher sensitivity and outstanding reproducibility. The higher anti-interference ability for response to an antibody makes it a promising method in application as a portable immuno-sensor. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Flexible Temperature Sensor Array Based on a Graphite-Polydimethylsiloxane Composite
Sensors 2010, 10(4), 3597-3610; doi:10.3390/s100403597
Received: 12 January 2010 / Revised: 12 March 2010 / Accepted: 20 March 2010 / Published: 9 April 2010
Cited by 40 | PDF Full-text (677 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a novel method to fabricate temperature sensor arrays by dispensing a graphite-polydimethylsiloxane composite on flexible polyimide films. The fabricated temperature sensor array has 64 sensing cells in a 4 × 4 cm2 area. The sensor array can be used
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This paper presents a novel method to fabricate temperature sensor arrays by dispensing a graphite-polydimethylsiloxane composite on flexible polyimide films. The fabricated temperature sensor array has 64 sensing cells in a 4 × 4 cm2 area. The sensor array can be used as humanoid artificial skin for sensation system of robots. Interdigitated copper electrodes were patterned on the flexible polyimide substrate for determining the resistivity change of the composites subjected to ambient temperature variations. Polydimethylsiloxane was used as the matrix. Composites of different graphite volume fractions for large dynamic range from 30 ºC to 110 ºC have been investigated. Our experiments showed that graphite powder provided the composite high temperature sensitivity. The fabricated temperature sensor array has been tested. The detected temperature contours are in good agreement with the shapes and magnitudes of different heat sources. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Relaxation Time Estimation from Complex Magnetic Resonance Images
Sensors 2010, 10(4), 3611-3625; doi:10.3390/s100403611
Received: 20 December 2009 / Revised: 23 February 2010 / Accepted: 24 March 2010 / Published: 9 April 2010
Cited by 20 | PDF Full-text (454 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic Resonance (MR) imaging techniques are used to measure biophysical properties of tissues. As clinical diagnoses are mainly based on the evaluation of contrast in MR images, relaxation times assume a fundamental role providing a major source of contrast. Moreover, they can give
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Magnetic Resonance (MR) imaging techniques are used to measure biophysical properties of tissues. As clinical diagnoses are mainly based on the evaluation of contrast in MR images, relaxation times assume a fundamental role providing a major source of contrast. Moreover, they can give useful information in cancer diagnostic. In this paper we present a statistical technique to estimate relaxation times exploiting complex-valued MR images. Working in the complex domain instead of the amplitude one allows us to consider the data bivariate Gaussian distributed, and thus to implement a simple Least Square (LS) estimator on the available complex data. The proposed estimator results to be simple, accurate and unbiased. Full article
(This article belongs to the Special Issue Image Sensors)
Open AccessArticle DMP: Detouring Using Multiple Paths against Jamming Attack for Ubiquitous Networking System
Sensors 2010, 10(4), 3626-3640; doi:10.3390/s100403626
Received: 9 February 2010 / Revised: 11 March 2010 / Accepted: 18 March 2010 / Published: 12 April 2010
Cited by 4 | PDF Full-text (787 KB) | HTML Full-text | XML Full-text
Abstract
To successfully realize the ubiquitous network environment including home automation or industrial control systems, it is important to be able to resist a jamming attack. This has recently been considered as an extremely threatening attack because it can collapse the entire network, despite
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To successfully realize the ubiquitous network environment including home automation or industrial control systems, it is important to be able to resist a jamming attack. This has recently been considered as an extremely threatening attack because it can collapse the entire network, despite the existence of basic security protocols such as encryption and authentication. In this paper, we present a method of jamming attack tolerant routing using multiple paths based on zones. The proposed scheme divides the network into zones, and manages the candidate forward nodes of neighbor zones. After detecting an attack, detour nodes decide zones for rerouting, and detour packets destined for victim nodes through forward nodes in the decided zones. Simulation results show that our scheme increases the PDR (Packet Delivery Ratio) and decreases the delay significantly in comparison with rerouting by a general routing protocol on sensor networks, AODV (Ad hoc On Demand Distance Vector), and a conventional JAM (Jammed Area Mapping) service with one reroute. Full article
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Open AccessArticle A Miniature System for Separating Aerosol Particles and Measuring Mass Concentrations
Sensors 2010, 10(4), 3641-3654; doi:10.3390/s100403641
Received: 3 February 2010 / Revised: 6 April 2010 / Accepted: 7 April 2010 / Published: 12 April 2010
Cited by 10 | PDF Full-text (636 KB) | HTML Full-text | XML Full-text
Abstract
We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different
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We designed and fabricated a new sensing system which consists of two virtual impactors and two quartz-crystal microbalance (QCM) sensors for measuring particle mass concentration and size distribution. The virtual impactors utilized different inertial forces of particles in air flow to classify different particle sizes. They were designed to classify particle diameter, d, into three different ranges: d < 2.28 μm, 2.28 μm ≤ d ≤ 3.20 μm, d > 3.20 μm. The QCM sensors were coated with a hydrogel, which was found to be a reliable adhesive for capturing aerosol particles. The QCM sensor coated with hydrogel was used to measure the mass loading of particles by utilizing its characteristic of resonant frequency shift. An integrated system has been demonstrated. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Localization of Mobile Robots Using Odometry and an External Vision Sensor
Sensors 2010, 10(4), 3655-3680; doi:10.3390/s100403655
Received: 15 January 2010 / Revised: 3 March 2010 / Accepted: 31 March 2010 / Published: 13 April 2010
Cited by 15 | PDF Full-text (3085 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a sensor system for robot localization based on the information obtained from a single camera attached in a fixed place external to the robot. Our approach firstly obtains the 3D geometrical model of the robot based on the projection of
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This paper presents a sensor system for robot localization based on the information obtained from a single camera attached in a fixed place external to the robot. Our approach firstly obtains the 3D geometrical model of the robot based on the projection of its natural appearance in the camera while the robot performs an initialization trajectory. This paper proposes a structure-from-motion solution that uses the odometry sensors inside the robot as a metric reference. Secondly, an online localization method based on a sequential Bayesian inference is proposed, which uses the geometrical model of the robot as a link between image measurements and pose estimation. The online approach is resistant to hard occlusions and the experimental setup proposed in this paper shows its effectiveness in real situations. The proposed approach has many applications in both the industrial and service robot fields. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle A New Automatic System for Angular Measurement and Calibration in Radiometric Instruments
Sensors 2010, 10(4), 3703-3717; doi:10.3390/s100403703
Received: 1 February 2010 / Revised: 19 March 2010 / Accepted: 30 March 2010 / Published: 13 April 2010
Cited by 3 | PDF Full-text (371 KB) | HTML Full-text | XML Full-text
Abstract
This paper puts forward the design, construction and testing of a new automatic system for angular-response measurement and calibration in radiometric instruments. Its main characteristics include precision, speed, resolution, noise immunity, easy programming and operation. The developed system calculates the cosine error of
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This paper puts forward the design, construction and testing of a new automatic system for angular-response measurement and calibration in radiometric instruments. Its main characteristics include precision, speed, resolution, noise immunity, easy programming and operation. The developed system calculates the cosine error of the radiometer under test by means of a virtual instrument, from the measures it takes and through a mathematical procedure, thus allowing correcting the radiometer with the aim of preventing cosine error in its measurements. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Authentication and Key Establishment in Dynamic Wireless Sensor Networks
Sensors 2010, 10(4), 3718-3731; doi:10.3390/s100403718
Received: 8 March 2010 / Revised: 6 April 2010 / Accepted: 6 April 2010 / Published: 13 April 2010
Cited by 21 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text
Abstract
When a sensor node roams within a very large and distributed wireless sensor network, which consists of numerous sensor nodes, its routing path and neighborhood keep changing. In order to provide a high level of security in this environment, the moving sensor node
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When a sensor node roams within a very large and distributed wireless sensor network, which consists of numerous sensor nodes, its routing path and neighborhood keep changing. In order to provide a high level of security in this environment, the moving sensor node needs to be authenticated to new neighboring nodes and a key established for secure communication. The paper proposes an efficient and scalable protocol to establish and update the authentication key in a dynamic wireless sensor network environment. The protocol guarantees that two sensor nodes share at least one key with probability 1 (100%) with less memory and energy cost, while not causing considerable communication overhead. Full article
Open AccessArticle A Multiwell Electrochemical Biosensor for Real-Time Monitoring of the Behavioural Changes of Cells in Vitro
Sensors 2010, 10(4), 3732-3740; doi:10.3390/s100403732
Received: 2 March 2010 / Revised: 1 April 2010 / Accepted: 6 April 2010 / Published: 13 April 2010
Cited by 4 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
We report the development of a multiwell biosensor for detecting changes in the electrochemical open circuit potential (OCP) generated by viable human cells in vitro. The instrument features eight culture wells; each containing three gold sensors around a common silver/silver chloride reference
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We report the development of a multiwell biosensor for detecting changes in the electrochemical open circuit potential (OCP) generated by viable human cells in vitro. The instrument features eight culture wells; each containing three gold sensors around a common silver/silver chloride reference electrode, prepared using screen-printed conductive inks. The potential applications of the device were demonstrated by monitoring rheumatoid synovial fibroblasts (RSF) and HepG2 hepatocarcinoma cells in response to chemical and biological treatments. This technology could provide an alternative to conventional end-point assays used in the fields of chemotherapy, toxicology and drug discovery. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
Open AccessArticle Error Analysis in a Stereo Vision-Based Pedestrian Detection Sensor for Collision Avoidance Applications
Sensors 2010, 10(4), 3741-3758; doi:10.3390/s100403741
Received: 25 January 2010 / Revised: 18 March 2010 / Accepted: 23 March 2010 / Published: 13 April 2010
Cited by 20 | PDF Full-text (910 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an analytical study of the depth estimation error of a stereo vision-based pedestrian detection sensor for automotive applications such as pedestrian collision avoidance and/or mitigation. The sensor comprises two synchronized and calibrated low-cost cameras. Pedestrians are detected by combining a
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This paper presents an analytical study of the depth estimation error of a stereo vision-based pedestrian detection sensor for automotive applications such as pedestrian collision avoidance and/or mitigation. The sensor comprises two synchronized and calibrated low-cost cameras. Pedestrians are detected by combining a 3D clustering method with Support Vector Machine-based (SVM) classification. The influence of the sensor parameters in the stereo quantization errors is analyzed in detail providing a point of reference for choosing the sensor setup according to the application requirements. The sensor is then validated in real experiments. Collision avoidance maneuvers by steering are carried out by manual driving. A real time kinematic differential global positioning system (RTK-DGPS) is used to provide ground truth data corresponding to both the pedestrian and the host vehicle locations. The performed field test provided encouraging results and proved the validity of the proposed sensor for being used in the automotive sector towards applications such as autonomous pedestrian collision avoidance. Full article
Open AccessCommunication Development of an Emergency Locking Unit for a Belt-In-Seat (BIS) System Using a MEMS Acceleration Sensor
Sensors 2010, 10(4), 3759-3770; doi:10.3390/s100403759
Received: 1 February 2010 / Revised: 7 April 2010 / Accepted: 8 April 2010 / Published: 14 April 2010
PDF Full-text (1261 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an emergency locking unit (ELU) for a seat belt retractor which is mounted on the back frame of a vehicle seat. The proposed unit uses a recliner sensor based on a MEMS acceleration sensor and solenoid mechanism. The seat has
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This paper proposes an emergency locking unit (ELU) for a seat belt retractor which is mounted on the back frame of a vehicle seat. The proposed unit uses a recliner sensor based on a MEMS acceleration sensor and solenoid mechanism. The seat has an upper frame supported to tilt on a lower frame. The retractor in belt in seat (BIS) system is supported by the upper frame. The proposed recliner sensor based on a MEMS acceleration sensor comprises orientation means for maintaining a predetermined orientation of emergency relative to the lower frame independently of the force of gravity when the upper frame tilts on the lower frame. Experimental results show that the developed recliner sensor unit operates effectively with respect to rollover angles. Thus, the developed unit will have a considerable potential to offer a new design concept in BIS system. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Alternative Sensor System and MLP Neural Network for Vehicle Pedal Activity Estimation
Sensors 2010, 10(4), 3798-3814; doi:10.3390/s100403798
Received: 19 January 2010 / Revised: 21 February 2010 / Accepted: 22 March 2010 / Published: 14 April 2010
Cited by 6 | PDF Full-text (562 KB) | HTML Full-text | XML Full-text
Abstract
It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver’s behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless
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It is accepted that the activity of the vehicle pedals (i.e., throttle, brake, clutch) reflects the driver’s behavior, which is at least partially related to the fuel consumption and vehicle pollutant emissions. This paper presents a solution to estimate the driver activity regardless of the type, model, and year of fabrication of the vehicle. The solution is based on an alternative sensor system (regime engine, vehicle speed, frontal inclination and linear acceleration) that reflects the activity of the pedals in an indirect way, to estimate that activity by means of a multilayer perceptron neural network with a single hidden layer. Full article
Open AccessArticle Optical Sensor for Characterizing the Phase Transition in Salted Solutions
Sensors 2010, 10(4), 3815-3823; doi:10.3390/s100403815
Received: 11 February 2010 / Revised: 27 February 2010 / Accepted: 17 March 2010 / Published: 14 April 2010
Cited by 9 | PDF Full-text (1779 KB) | HTML Full-text | XML Full-text
Abstract
We propose a new optical sensor to characterize the solid-liquid phase transition in salted solutions. The probe mainly consists of a Raman spectrometer that extracts the vibrational properties from the light scattered by the salty medium. The spectrum of the O-H stretching band
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We propose a new optical sensor to characterize the solid-liquid phase transition in salted solutions. The probe mainly consists of a Raman spectrometer that extracts the vibrational properties from the light scattered by the salty medium. The spectrum of the O-H stretching band was shown to be strongly affected by the introduction of NaCl and the temperature change as well. A parameter SD defined as the ratio of the integrated intensities of two parts of this band allows to study the temperature and concentration dependences of the phase transition. Then, an easy and efficient signal processing and the exploitation of a modified Boltzmann equation give information on the phase transition. Validations were done on solutions with varying concentration of NaCl. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle On BER Performance of EBPSK-MODEM in AWGN Channel
Sensors 2010, 10(4), 3824-3834; doi:10.3390/s100403824
Received: 25 February 2010 / Revised: 30 March 2010 / Accepted: 1 April 2010 / Published: 14 April 2010
Cited by 34 | PDF Full-text (153 KB) | HTML Full-text | XML Full-text
Abstract
In order to satisfy the higher and higher demand for communication systems, an Extended Binary Phase Shift Keying (EBPSK) system with very high spectra efficiency has been proposed. During the research, a special kind of filters was found, which can amplify the signal
[...] Read more.
In order to satisfy the higher and higher demand for communication systems, an Extended Binary Phase Shift Keying (EBPSK) system with very high spectra efficiency has been proposed. During the research, a special kind of filters was found, which can amplify the signal characteristics and remove utmost noise, i.e., at the point of the phase jumping corresponding to code “1”, produce the amplitude impulse much higher than code “0”, therefore, the aim of our study was to analyze the BER performance of the impacting filter assisted EBPSK-MODEM. Considering the receiver filtered “0” and “1”signal with Rice amplitude distribution, just having different mean values, so the BER performance of EBPSK is deduced based on the classic detection theory, and compared with the traditional BPSK modulation both in spectra efficiency and in BER performance, which lays the theoretical foundation for the feasibility of Ultra Narrow Band communications based on EBPSK modulation. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Design, Fabrication, and Testing of a Bulk Micromachined Inertial Measurement Unit
Sensors 2010, 10(4), 3835-3856; doi:10.3390/s100403835
Received: 22 February 2010 / Revised: 17 March 2010 / Accepted: 6 April 2010 / Published: 14 April 2010
Cited by 5 | PDF Full-text (582 KB) | HTML Full-text | XML Full-text
Abstract
A bulk micromachined inertial measurement unit (MIMU) is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global
[...] Read more.
A bulk micromachined inertial measurement unit (MIMU) is presented in this paper. Three single-axis accelerometers and three single-axis gyroscopes were simultaneously fabricated on a silicon wafer using a bulk micromachining process; the wafer is smaller than one square centimeter. In particular, a global area optimization method based on the relationship between the sensitivity and layout area was proposed to determine the layout configuration of the six sensors. The scale factors of the X/Y-axis accelerometer and Z-axis accelerometer are about 213.3 mV/g and 226.9 mV/g, respectively. The scale factors of the X/Y-axis gyroscope and Z-axis gyroscope are about 2.2 mV/o/s and 10.8 mV/o/s, respectively. The bias stability of the X/Y-axis gyroscope and the Z-axis gyroscope are about 2135 deg/h and 80 deg/h, respectively. Finally, the resolutions of X/Y-axis accelerometers, Z-axis accelerometers, X/Y-axis gyroscopes, and Z-axis gyroscopes are 0.0012 g/ √Hz, 0.0011 g/ √Hz, 0.314 °/s/ √Hz, and 0.008 °/s/ √Hz, respectively. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle Carbon Nanotube Integration with a CMOS Process
Sensors 2010, 10(4), 3857-3867; doi:10.3390/s100403857
Received: 27 January 2010 / Revised: 6 April 2010 / Accepted: 9 April 2010 / Published: 15 April 2010
Cited by 2 | PDF Full-text (1111 KB) | HTML Full-text | XML Full-text
Abstract
This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs
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This work shows the integration of a sensor based on carbon nanotubes using CMOS technology. A chip sensor (CS) was designed and manufactured using a 0.30 μm CMOS process, leaving a free window on the passivation layer that allowed the deposition of SWCNTs over the electrodes. We successfully investigated with the CS the effect of humidity and temperature on the electrical transport properties of SWCNTs. The possibility of a large scale integration of SWCNTs with CMOS process opens a new route in the design of more efficient, low cost sensors with high reproducibility in their manufacture. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Spectroscopic Interpretation of PAH-Spectra in Minerals and Its Possible Application to Soil Monitoring
Sensors 2010, 10(4), 3868-3881; doi:10.3390/s100403868
Received: 3 February 2010 / Revised: 6 April 2010 / Accepted: 7 April 2010 / Published: 15 April 2010
Cited by 4 | PDF Full-text (597 KB) | HTML Full-text | XML Full-text
Abstract
In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants,
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In order to properly assess the feasibility of using Laser-Induced Fluorescence (LIF) spectroscopy for soil monitoring, the variation of fluorescence intensity due to the heterogeneity and complexity of soil media was investigated. Different soil minerals showed fluorescence spectral structures distinguishable from the contaminants, implying dissimilar interactions or the binding of contaminants on mineral surfaces. More interestingly, solvent and water addition showed different responses in the fluorescence spectral structure showing their effect on the interactions between contaminants and minerals. These results support the claim that the spectral structure contains information on contaminant-mineral interactions; therefore contaminants can be used as a fluorescence probe for these interactions. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessArticle BARI+: A Biometric Based Distributed Key Management Approach for Wireless Body Area Networks
Sensors 2010, 10(4), 3911-3933; doi:10.3390/s100403911
Received: 6 February 2010 / Revised: 6 March 2010 / Accepted: 7 April 2010 / Published: 16 April 2010
Cited by 20 | PDF Full-text (472 KB) | HTML Full-text | XML Full-text
Abstract
Wireless body area networks (WBAN) consist of resource constrained sensing devices just like other wireless sensor networks (WSN). However, they differ from WSN in topology, scale and security requirements. Due to these differences, key management schemes designed for WSN are inefficient and unnecessarily
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Wireless body area networks (WBAN) consist of resource constrained sensing devices just like other wireless sensor networks (WSN). However, they differ from WSN in topology, scale and security requirements. Due to these differences, key management schemes designed for WSN are inefficient and unnecessarily complex when applied to WBAN. Considering the key management issue, WBAN are also different from WPAN because WBAN can use random biometric measurements as keys. We highlight the differences between WSN and WBAN and propose an efficient key management scheme, which makes use of biometrics and is specifically designed for WBAN domain. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Monitoring and Advisory System for Diabetes Patient Management Using a Rule-Based Method and KNN
Sensors 2010, 10(4), 3934-3953; doi:10.3390/s100403934
Received: 25 January 2010 / Revised: 17 March 2010 / Accepted: 30 March 2010 / Published: 19 April 2010
PDF Full-text (936 KB) | HTML Full-text | XML Full-text
Abstract
Diabetes is difficult to control and it is important to manage the diabetic’s blood sugar level and prevent the associated complications by appropriate diabetic treatment. This paper proposes a system that can provide appropriate management for diabetes patients, according to their blood sugar
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Diabetes is difficult to control and it is important to manage the diabetic’s blood sugar level and prevent the associated complications by appropriate diabetic treatment. This paper proposes a system that can provide appropriate management for diabetes patients, according to their blood sugar level. The system is designed to send the information about the blood sugar levels, blood pressure, food consumption, exercise, etc., of diabetes patients, and manage the treatment by recommending and monitoring food consumption, physical activity, insulin dosage, etc., so that the patient can better manage their condition. The system is based on rules and the K Nearest Neighbor (KNN) classifier algorithm, to obtain the optimum treatment recommendation. Also, a monitoring system for diabetes patients is implemented using Web Services and Personal Digital Assistant (PDA) programming. Full article
Open AccessArticle Greatly Improved Small Inductance Measurement Using Quartz Crystal Parasitic Capacitance Compensation
Sensors 2010, 10(4), 3954-3960; doi:10.3390/s100403954
Received: 3 February 2010 / Revised: 23 March 2010 / Accepted: 23 March 2010 / Published: 20 April 2010
Cited by 9 | PDF Full-text (145 KB) | HTML Full-text | XML Full-text
Abstract
Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequencypullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working
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Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequencypullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working near the antiresonance frequency is selected. By modifying its equivalent circuit with load inductance and series tuning capacitance, the magnetic sensing of the circuit can be highly improved. The experimental results show that the new approach using the quartz crystal stray capacitance compensation method increases the frequency pulling range (from ≅ 2 kHz/mH to ≅ 600 kHz/mH) by × 300 depending on the type of oscillator, making possible the measurement of nano-magnetic changes. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessArticle Spectral Identification of Lighting Type and Character
Sensors 2010, 10(4), 3961-3988; doi:10.3390/s100403961
Received: 22 February 2010 / Revised: 12 March 2010 / Accepted: 6 April 2010 / Published: 20 April 2010
Cited by 66 | PDF Full-text (1626 KB) | HTML Full-text | XML Full-text
Abstract
We investigated the optimal spectral bands for the identification of lighting types and the estimation of four major indices used to measure the efficiency or character of lighting. To accomplish these objectives we collected high-resolution emission spectra (350 to 2,500 nm) for forty-three
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We investigated the optimal spectral bands for the identification of lighting types and the estimation of four major indices used to measure the efficiency or character of lighting. To accomplish these objectives we collected high-resolution emission spectra (350 to 2,500 nm) for forty-three different lamps, encompassing nine of the major types of lamps used worldwide. The narrow band emission spectra were used to simulate radiances in eight spectral bands including the human eye photoreceptor bands (photopic, scotopic, and “meltopic”) plus five spectral bands in the visible and near-infrared modeled on bands flown on the Landsat Thematic Mapper (TM). The high-resolution continuous spectra are superior to the broad band combinations for the identification of lighting type and are the standard for calculation of Luminous Efficacy of Radiation (LER), Correlated Color Temperature (CCT) and Color Rendering Index (CRI). Given the high cost that would be associated with building and flying a hyperspectral sensor with detection limits low enough to observe nighttime lights we conclude that it would be more feasible to fly an instrument with a limited number of broad spectral bands in the visible to near infrared. The best set of broad spectral bands among those tested is blue, green, red and NIR bands modeled on the band set flown on the Landsat Thematic Mapper. This set provides low errors on the identification of lighting types and reasonable estimates of LER and CCT when compared to the other broad band set tested. None of the broad band sets tested could make reasonable estimates of Luminous Efficacy (LE) or CRI. The photopic band proved useful for the estimation of LER. However, the three photoreceptor bands performed poorly in the identification of lighting types when compared to the bands modeled on the Landsat Thematic Mapper. Our conclusion is that it is feasible to identify lighting type and make reasonable estimates of LER and CCT using four or more spectral bands with minimal spectral overlap spanning the 0.4 to 1.0 um region. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle In Situ Roughness Measurements for the Solar Cell Industry Using an Atomic Force Microscope
Sensors 2010, 10(4), 4002-4009; doi:10.3390/s100404002
Received: 13 January 2010 / Revised: 20 February 2010 / Accepted: 7 April 2010 / Published: 20 April 2010
Cited by 4 | PDF Full-text (762 KB) | HTML Full-text | XML Full-text
Abstract
Areal roughness parameters always need to be under control in the thin film solar cell industry because of their close relationship with the electrical efficiency of the cells. In this work, these parameters are evaluated for measurements carried out in a typical fabrication
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Areal roughness parameters always need to be under control in the thin film solar cell industry because of their close relationship with the electrical efficiency of the cells. In this work, these parameters are evaluated for measurements carried out in a typical fabrication area for this industry. Measurements are made using a portable atomic force microscope on the CNC diamond cutting machine where an initial sample of transparent conductive oxide is cut into four pieces. The method is validated by making a comparison between the parameters obtained in this process and in the laboratory under optimal conditions. Areal roughness parameters and Fourier Spectral Analysis of the data show good compatibility and open the possibility to use this type of measurement instrument to perform in situ quality control. This procedure gives a sample for evaluation without destroying any of the transparent conductive oxide; in this way 100% of the production can be tested, so improving the measurement time and rate of production. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Design and Analysis of Impedance Pumps Utilizing Electromagnetic Actuation
Sensors 2010, 10(4), 4040-4052; doi:10.3390/s100404040
Received: 25 February 2010 / Revised: 19 March 2010 / Accepted: 9 April 2010 / Published: 21 April 2010
Cited by 17 | PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS
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This study designs and analyzes an impedance pump utilizing an electromagnetic actuator. The pump is designed to have three major components, namely a lower glass substrate patterned with a copper micro-coil, a microchannel, and an upper glass cover plate attached a magnetic PDMS diaphragm. When a current is passed through the micro-coil, an electromagnetic force is established between the coil and the magnetic diaphragm. The resulting deflection of the PDMS diaphragm creates an acoustic impedance mismatch within the microchannel, which results in a net flow. In performing the analysis, simulated models of the magnetic field, the diaphragm displacement and the flow rate are developed using Ansoft/Maxwell3D, ANSYS FEA and FLUENT 6.3 CFD software, respectively. Overall, the simulated results reveal that a net flow rate of 52.8 μL/min can be obtained using a diaphragm displacement of 31.5 μm induced by a micro-coil input current of 0.5 A. The impedance pump proposed in this study provides a valuable contribution to the ongoing development of Lab-on-Chips (LoCs) systems. Full article
(This article belongs to the Special Issue Advances in Actuators)
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Open AccessArticle Fluorescence-Based Comparative Binding Studies of the Supramolecular Host Properties of PAMAM Dendrimers Using Anilinonaphthalene Sulfonates: Unusual Host-Dependent Fluorescence Titration Behavior
Sensors 2010, 10(4), 4053-4070; doi:10.3390/s100404053
Received: 4 March 2010 / Revised: 31 March 2010 / Accepted: 13 April 2010 / Published: 21 April 2010
Cited by 6 | PDF Full-text (362 KB) | HTML Full-text | XML Full-text
Abstract
This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies,
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This work describes the fluorescence enhancement of the anilinonaphthalene sulfonate probes 1,8-ANS, 2,6-ANS, and 2,6-TNS via complexation with PAMAM dendrimer hosts of Generation 4, 5 and 6. The use of this set of three very closely related probes allows for comparative binding studies, with specific pairs of probes differing only in shape (1,8-ANS and 2,6-ANS), or in the presence of a methyl substituent (2,6-TNS vs. 2,6-ANS). The fluorescence of all three probes was significantly enhanced upon binding with PAMAM dendrimers, however in all cases except one, a very unusual spike was consistently observed in the host fluorescence titration plots (fluorescence enhancement vs. host concentration) at low dendrimer concentration. This unprecedented fluorescence titration curve shape makes fitting the data to a simple model such as 1:1 or 2:1 host: guest complexation very difficult; thus only qualitative comparisons of the relative binding of the three guests could be made based on host titrations. In the case of G4 and G5 dendrimers, the order of binding strength was qualitatively determined to be 1,8-ANS < 2,6-ANS indicating that the more streamlined 2,6-substituted probes are a better match for the dendrimer cavity shape than the bulkier 1,8-substituted probe. This order of binding strength was also indicated by double fluorometric titration experiments, involving both host and guest titrations. Further double fluorometric titration experiments on 2,6-ANS in G4 dendrimer revealed a host concentration-dependent change in the nature of the host: guest complexation, with multiple guests complexed per host molecule at very low host concentrations, but less than one guest per host at higher concentrations. Full article
(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)
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Open AccessArticle Towards Fully Integrated Wireless Impedimetric Sensors
Sensors 2010, 10(4), 4071-4082; doi:10.3390/s100404071
Received: 21 February 2010 / Revised: 10 March 2010 / Accepted: 13 April 2010 / Published: 21 April 2010
Cited by 10 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and
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We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and a metal coil and circuits for inductive power and data transfer. The electrodes have been formed with a polycrystalline silicon layer of the technology by a simple post-process that does not require additional deposition or lithography steps, but just etching steps. A linear response to both conductivity and permittivity of solutions has been obtained. Wireless communication of the sensor chip with a readout unit has been demonstrated. The design of the chip was prepared for individual block characterization and not for full system characterization. The integration of chemical transducers within monolithic wireless platforms will lead to smaller, cheaper, and more reliable chemical microsensors, and will open up the door to numerous new applications where liquid mediums that are enclosed in sealed receptacles have to be measured. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Ultra-High-Speed Image Signal Accumulation Sensor
Sensors 2010, 10(4), 4100-4113; doi:10.3390/s100404100
Received: 24 March 2010 / Revised: 8 April 2010 / Accepted: 16 April 2010 / Published: 23 April 2010
Cited by 7 | PDF Full-text (1901 KB) | HTML Full-text | XML Full-text
Abstract
Averaging of accumulated data is a standard technique applied to processing data with low signal-to-noise ratios (SNR), such as image signals captured in ultra-high-speed imaging. The authors propose an architecture layout of an ultra-high-speed image sensor capable of on-chip signal accumulation. The very
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Averaging of accumulated data is a standard technique applied to processing data with low signal-to-noise ratios (SNR), such as image signals captured in ultra-high-speed imaging. The authors propose an architecture layout of an ultra-high-speed image sensor capable of on-chip signal accumulation. The very high frame rate is enabled by employing an image sensor structure with a multi-folded CCD in each pixel, which serves as an in situ image signal storage. The signal accumulation function is achieved by direct connection of the first and the last storage elements of the in situ storage CCD. It has been thought that the multi-folding is achievable only by driving electrodes with complicated and impractical layouts. Simple configurations of the driving electrodes to overcome the difficulty are presented for two-phase and four-phase transfer CCD systems. The in situ storage image sensor with the signal accumulation function is named Image Signal Accumulation Sensor (ISAS). Full article
(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)
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Open AccessArticle FPGA-Based Fused Smart Sensor for Dynamic and Vibration Parameter Extraction in Industrial Robot Links
Sensors 2010, 10(4), 4114-4129; doi:10.3390/s100404114
Received: 2 March 2010 / Revised: 20 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 18 | PDF Full-text (3738 KB) | HTML Full-text | XML Full-text
Abstract
Intelligent robotics demands the integration of smart sensors that allow the controller to efficiently measure physical quantities. Industrial manipulator robots require a constant monitoring of several parameters such as motion dynamics, inclination, and vibration. This work presents a novel smart sensor to estimate
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Intelligent robotics demands the integration of smart sensors that allow the controller to efficiently measure physical quantities. Industrial manipulator robots require a constant monitoring of several parameters such as motion dynamics, inclination, and vibration. This work presents a novel smart sensor to estimate motion dynamics, inclination, and vibration parameters on industrial manipulator robot links based on two primary sensors: an encoder and a triaxial accelerometer. The proposed smart sensor implements a new methodology based on an oversampling technique, averaging decimation filters, FIR filters, finite differences and linear interpolation to estimate the interest parameters, which are computed online utilizing digital hardware signal processing based on field programmable gate arrays (FPGA). Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Design and Simulation of a MEMS Control Moment Gyroscope for the Sub-Kilogram Spacecraft
Sensors 2010, 10(4), 4130-4144; doi:10.3390/s100404130
Received: 8 March 2010 / Revised: 19 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 5 | PDF Full-text (465 KB) | HTML Full-text | XML Full-text
Abstract
A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor
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A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10-6 N∙m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal; the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10-8 N∙m. The element with four MCMGs could generate a torque of 5 × 10-8 N∙m. The torque output could reach a magnitude of 10-6 N∙m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96s. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Corrosion Sensor for Monitoring the Service Condition of Chloride-Contaminated Cement Mortar
Sensors 2010, 10(4), 4145-4158; doi:10.3390/s100404145
Received: 4 March 2010 / Revised: 13 April 2010 / Accepted: 19 April 2010 / Published: 26 April 2010
Cited by 7 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text
Abstract
A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear
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A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Non-Linearity Analysis of Depth and Angular Indexes for Optimal Stereo SLAM
Sensors 2010, 10(4), 4159-4179; doi:10.3390/s100404159
Received: 22 March 2010 / Revised: 19 April 2010 / Accepted: 20 April 2010 / Published: 26 April 2010
Cited by 4 | PDF Full-text (607 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3–5 km/h. We present the
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In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3–5 km/h. We present the basis for a vision-based system that would assist the navigation of the visually impaired by either providing information about their current position and orientation or guiding them to their destination through different sensing modalities. Our sensor combines two different types of feature parametrization: inverse depth and 3D in order to provide orientation and depth information at the same time. Natural landmarks are extracted from the image and are stored as 3D or inverse depth points, depending on a depth threshold. This depth threshold is used for switching between both parametrizations and it is computed by means of a non-linearity analysis of the stereo sensor. Main steps of our system approach are presented as well as an analysis about the optimal way to calculate the depth threshold. At the moment each landmark is initialized, the normal of the patch surface is computed using the information of the stereo pair. In order to improve long-term tracking, a patch warping is done considering the normal vector information. Some experimental results under indoor environments and conclusions are presented. Full article
(This article belongs to the Special Issue Motion Detectors)

Review

Jump to: Research

Open AccessReview DFB Lasers Between 760 nm and 16 µm for Sensing Applications
Sensors 2010, 10(4), 2492-2510; doi:10.3390/s100402492
Received: 20 January 2010 / Revised: 22 February 2010 / Accepted: 6 March 2010 / Published: 24 March 2010
Cited by 63 | PDF Full-text (764 KB) | HTML Full-text | XML Full-text
Abstract
Recent years have shown the importance of tunable semiconductor lasers in optical sensing. We describe the status quo concerning DFB laser diodes between 760 nm and 3,000 nm as well as new developments aiming for up to 80 nm tuning range in this
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Recent years have shown the importance of tunable semiconductor lasers in optical sensing. We describe the status quo concerning DFB laser diodes between 760 nm and 3,000 nm as well as new developments aiming for up to 80 nm tuning range in this spectral region. Furthermore we report on QCL between 3 µm and 16 µm and present new developments. An overview of the most interesting applications using such devices is given at the end of this paper. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
Open AccessReview State-of-the-Art of (Bio)Chemical Sensor Developments in Analytical Spanish Groups
Sensors 2010, 10(4), 2511-2576; doi:10.3390/s100402511
Received: 23 December 2009 / Revised: 3 February 2010 / Accepted: 28 February 2010 / Published: 24 March 2010
Cited by 15 | PDF Full-text (341 KB) | HTML Full-text | XML Full-text
Abstract
(Bio)chemical sensors are one of the most exciting fields in analytical chemistry today. The development of these analytical devices simplifies and miniaturizes the whole analytical process. Although the initial expectation of the massive incorporation of sensors in routine analytical work has been truncated
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(Bio)chemical sensors are one of the most exciting fields in analytical chemistry today. The development of these analytical devices simplifies and miniaturizes the whole analytical process. Although the initial expectation of the massive incorporation of sensors in routine analytical work has been truncated to some extent, in many other cases analytical methods based on sensor technology have solved important analytical problems. Many research groups are working in this field world-wide, reporting interesting results so far. Modestly, Spanish researchers have contributed to these recent developments. In this review, we summarize the more representative achievements carried out for these groups. They cover a wide variety of sensors, including optical, electrochemical, piezoelectric or electro-mechanical devices, used for laboratory or field analyses. The capabilities to be used in different applied areas are also critically discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain)
Open AccessReview Sensing and Tactile Artificial Muscles from Reactive Materials
Sensors 2010, 10(4), 2638-2674; doi:10.3390/s100402638
Received: 22 January 2010 / Revised: 17 February 2010 / Accepted: 2 March 2010 / Published: 25 March 2010
Cited by 47 | PDF Full-text (1098 KB) | HTML Full-text | XML Full-text
Abstract
Films of conducting polymers can be oxidized and reduced in a reversible way. Any intermediate oxidation state determines an electrochemical equilibrium. Chemical or physical variables acting on the film may modify the equilibrium potential, so that the film acts as a sensor of
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Films of conducting polymers can be oxidized and reduced in a reversible way. Any intermediate oxidation state determines an electrochemical equilibrium. Chemical or physical variables acting on the film may modify the equilibrium potential, so that the film acts as a sensor of the variable. The working potential of polypyrrole/DBSA (Dodecylbenzenesulfonic acid) films, oxidized or reduced under constant currents, changes as a function of the working conditions: electrolyte concentration, temperature or mechanical stress. During oxidation, the reactive material is a sensor of the ambient, the consumed electrical energy being the sensing magnitude. Devices based on any of the electrochemical properties of conducting polymers must act simultaneously as sensors of the working conditions. Artificial muscles, as electrochemical actuators constituted by reactive materials, respond to the ambient conditions during actuation. In this way, they can be used as actuators, sensing the surrounding conditions during actuation. Actuating and sensing signals are simultaneously included by the same two connecting wires. Full article
(This article belongs to the Special Issue Advances in Actuators)
Open AccessReview Oxidant Sensing by Protein Kinases A and G Enables Integration of Cell Redox State with Phosphoregulation
Sensors 2010, 10(4), 2731-2751; doi:10.3390/s100402731
Received: 11 January 2010 / Revised: 19 March 2010 / Accepted: 22 March 2010 / Published: 26 March 2010
Cited by 6 | PDF Full-text (3567 KB) | HTML Full-text | XML Full-text
Abstract
The control of vascular smooth muscle contractility enables regulation of blood pressure, which is paramount in physiological adaptation to environmental challenges. Maintenance of stable blood pressure is crucial for health as deregulation (caused by high or low blood pressure) leads to disease progression.
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The control of vascular smooth muscle contractility enables regulation of blood pressure, which is paramount in physiological adaptation to environmental challenges. Maintenance of stable blood pressure is crucial for health as deregulation (caused by high or low blood pressure) leads to disease progression. Vasotone is principally controlled by the cyclic nucleotide dependent protein kinases A and G, which regulate intracellular calcium and contractile protein calcium sensitivity. The classical pathways for activation of these two kinases are well established and involve the formation and activation by specific cyclic nucleotide second messengers. Recently we reported that both PKA and PKG can be regulated independently of their respective cyclic nucleotides via a mechanism whereby the kinases sense cellular oxidant production using redox active thiols. This novel redox regulation of these kinases is potentially of physiological importance, and may synergise with the classical regulatory mechanisms. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in the UK)
Open AccessReview Environmentally Sensitive Fluorescent Sensors Based on Synthetic Peptides
Sensors 2010, 10(4), 3126-3144; doi:10.3390/s100403126
Received: 6 January 2010 / Revised: 27 February 2010 / Accepted: 24 March 2010 / Published: 31 March 2010
Cited by 9 | PDF Full-text (293 KB) | HTML Full-text | XML Full-text
Abstract
Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes,
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Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, based on peptidic receptors labeled with environmentally sensitive fluorophores. Fluorescent indicators based on synthetic peptides are highly interesting alternatives to protein-based sensors, since they can be synthesized chemically, are stable, and can be easily modified in a site-specific manner for fluorophore coupling and for immobilization on solid supports. Full article
(This article belongs to the Special Issue Fluorescent Chemosensors)
Open AccessReview Visual Pathways Serving Motion Detection in the Mammalian Brain
Sensors 2010, 10(4), 3218-3242; doi:10.3390/s100403218
Received: 5 February 2010 / Revised: 16 March 2010 / Accepted: 17 March 2010 / Published: 1 April 2010
Cited by 4 | PDF Full-text (449 KB) | HTML Full-text | XML Full-text
Abstract
Motion perception is the process through which one gathers information on the dynamic visual world, in terms of the speed and movement direction of its elements. Motion sensation takes place from the retinal light sensitive elements, through the visual thalamus, the primary and
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Motion perception is the process through which one gathers information on the dynamic visual world, in terms of the speed and movement direction of its elements. Motion sensation takes place from the retinal light sensitive elements, through the visual thalamus, the primary and higher visual cortices. In the present review we aim to focus on the extrageniculo-extrastriate cortical and subcortical visual structures of the feline and macaque brain and discuss their functional role in visual motion perception. Special attention is paid to the ascending tectofugal system that may serve for detection of the visual environment during self-motion. Full article
(This article belongs to the Special Issue Motion Detectors)
Open AccessReview Advanced Taste Sensors Based on Artificial Lipids with Global Selectivity to Basic Taste Qualities and High Correlation to Sensory Scores
Sensors 2010, 10(4), 3411-3443; doi:10.3390/s100403411
Received: 28 January 2010 / Revised: 29 March 2010 / Accepted: 30 March 2010 / Published: 8 April 2010
Cited by 128 | PDF Full-text (500 KB) | HTML Full-text | XML Full-text
Abstract
Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These
[...] Read more.
Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These sensors respond similarly to similar basic tastes, which they quantify with high correlations to sensory score. Using these unique properties, these sensors can quantify the basic tastes of saltiness, sourness, bitterness, umami, astringency and richness without multivariate analysis or artificial neural networks. This review describes all aspects of these taste sensors based on artificial lipid, ranging from the response principle and optimal design methods to applications in the food, beverage, and pharmaceutical markets. Full article
(This article belongs to the Special Issue Advances in Transducers)
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Open AccessReview Structures and Encapsulation Motifs of Functional Molecules Probed by Laser Spectroscopic and Theoretical Methods
Sensors 2010, 10(4), 3519-3548; doi:10.3390/s100403519
Received: 29 January 2010 / Revised: 20 February 2010 / Accepted: 8 March 2010 / Published: 8 April 2010
Cited by 14 | PDF Full-text (1845 KB) | HTML Full-text | XML Full-text
Abstract
We report laser spectroscopic and computational studies of host/guest hydration interactions between functional molecules (hosts) and water (guest) in supersonic jets. The examined hosts include dibenzo-18-crown-6-ether (DB18C6), benzo-18-crown-6-ether (B18C6) and calix[4]arene (C4A). The gaseous complexes between the functional molecular hosts and water are
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We report laser spectroscopic and computational studies of host/guest hydration interactions between functional molecules (hosts) and water (guest) in supersonic jets. The examined hosts include dibenzo-18-crown-6-ether (DB18C6), benzo-18-crown-6-ether (B18C6) and calix[4]arene (C4A). The gaseous complexes between the functional molecular hosts and water are generated under jet-cooled conditions. Various laser spectroscopic methods are applied for these species: the electronic spectra are observed by laser-induced fluorescence (LIF), mass-selected resonance enhanced multiphoton ionization (REMPI) and ultraviolet-ultraviolet hole-burning (UV-UV HB) spectroscopy, whereas the vibrational spectra for each individual species are observed by infrared-ultraviolet double resonance (IR-UV DR) spectroscopy. The obained results are analyzed by first principles electronic structure calculations. We discuss the conformations of the host molecules, the structures of the complexes, and key interactions forming the specific complexes. Full article
(This article belongs to the Special Issue Laser Spectroscopy and Sensing)
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Open AccessReview Potential for Development of an Escherichia coli—Based Biosensor for Assessing Bioavailable Methionine: A Review
Sensors 2010, 10(4), 3562-3584; doi:10.3390/s100403562
Received: 8 February 2010 / Revised: 11 March 2010 / Accepted: 26 March 2010 / Published: 8 April 2010
Cited by 6 | PDF Full-text (395 KB) | HTML Full-text | XML Full-text
Abstract
Methionine is an essential amino acid for animals and is typically considered one of the first limiting amino acids in animal feed formulations. Methionine deficiency or excess in animal diets can lead to sub-optimal animal performance and increased environmental pollution, which necessitates its
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Methionine is an essential amino acid for animals and is typically considered one of the first limiting amino acids in animal feed formulations. Methionine deficiency or excess in animal diets can lead to sub-optimal animal performance and increased environmental pollution, which necessitates its accurate quantification and proper dosage in animal rations. Animal bioassays are the current industry standard to quantify methionine bioavailability. However, animal-based assays are not only time consuming, but expensive and are becoming more scrutinized by governmental regulations. In addition, a variety of artifacts can hinder the variability and time efficacy of these assays. Microbiological assays, which are based on a microbial response to external supplementation of a particular nutrient such as methionine, appear to be attractive potential alternatives to the already established standards. They are rapid and inexpensive in vitro assays which are characterized with relatively accurate and consistent estimation of digestible methionine in feeds and feed ingredients. The current review discusses the potential to develop Escherichia coli-based microbial biosensors for methionine bioavailability quantification. Methionine biosynthesis and regulation pathways are overviewed in relation to genetic manipulation required for the generation of a respective methionine auxotroph that could be practical for a routine bioassay. A prospective utilization of Escherichia coli methionine biosensor would allow for inexpensive and rapid methionine quantification and ultimately enable timely assessment of nutritional profiles of feedstuffs. Full article
(This article belongs to the Special Issue Microbial Sensors and Biosensors)
Open AccessReview Quantitative Modeling of Coupled Piezo-Elastodynamic Behavior of Piezoelectric Actuators Bonded to an Elastic Medium for Structural Health Monitoring: A Review
Sensors 2010, 10(4), 3681-3702; doi:10.3390/s100403681
Received: 6 January 2010 / Revised: 16 March 2010 / Accepted: 31 March 2010 / Published: 13 April 2010
Cited by 38 | PDF Full-text (947 KB) | HTML Full-text | XML Full-text
Abstract
Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to
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Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor network, have shown great potential for on-line health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials can function as both actuators and sensors in these applications due to wide bandwidth, quick response and low costs. One of the most fundamental issues surrounding the effective use of piezoelectric actuators is the quantitative evaluation of the resulting elastic wave propagation by considering the coupled piezo-elastodynamic behavior between the actuator and the host medium. Accurate characterization of the local interfacial stress distribution between the actuator and the host medium is the key issue for the problem. This paper presents a review of the development of analytical, numerical and hybrid approaches for modeling of the coupled piezo-elastodynamic behavior. The resulting elastic wave propagation for structural health monitoring is also summarized. Full article
(This article belongs to the Special Issue Advances in Actuators)
Open AccessReview Optoelectronic Capillary Sensors in Microfluidic and Point-of-Care Instrumentation
Sensors 2010, 10(4), 3771-3797; doi:10.3390/s100403771
Received: 15 February 2010 / Revised: 10 March 2010 / Accepted: 30 March 2010 / Published: 14 April 2010
Cited by 22 | PDF Full-text (489 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical
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This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical sensors, systematizing the various types of sensors from the point of view of the principles of their construction and operation. Unlike classical fiber-optic sensors which rely on changes in light propagation inside the fiber as affected by outside conditions, optical capillary sensors rely on changes of light transmission in capillaries filled with the analyzed liquid, which opens the possibility of interesting new applications, while raising specific issues relating to the construction, materials and instrumentation of those sensors. Full article
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Open AccessReview Metal Oxide Sensors for Electronic Noses and Their Application to Food Analysis
Sensors 2010, 10(4), 3882-3910; doi:10.3390/s100403882
Received: 11 March 2010 / Revised: 12 April 2010 / Accepted: 13 April 2010 / Published: 15 April 2010
Cited by 91 | PDF Full-text (394 KB) | HTML Full-text | XML Full-text
Abstract
Electronic noses (E-noses) use various types of electronic gas sensors that have partial specificity. This review focuses on commercial and experimental E-noses that use metal oxide semi-conductors. The review covers quality control applications to food and beverages, including determination of freshness and identification
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Electronic noses (E-noses) use various types of electronic gas sensors that have partial specificity. This review focuses on commercial and experimental E-noses that use metal oxide semi-conductors. The review covers quality control applications to food and beverages, including determination of freshness and identification of contaminants or adulteration. Applications of E-noses to a wide range of foods and beverages are considered, including: meat, fish, grains, alcoholic drinks, non-alcoholic drinks, fruits, milk and dairy products, olive oils, nuts, fresh vegetables and eggs. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)
Open AccessReview Challenges in the Assembly and Handling of Thin Film Capped MEMS Devices
Sensors 2010, 10(4), 3989-4001; doi:10.3390/s100403989
Received: 5 January 2010 / Revised: 8 March 2010 / Accepted: 22 March 2010 / Published: 20 April 2010
Cited by 6 | PDF Full-text (809 KB) | HTML Full-text | XML Full-text
Abstract
This paper discusses the assembly challenges considering the design and manufacturability of a Wafer Level Thin Film Package in MEMS applications. The assembly processes are discussed. The loads associated with these processes are illustrated and evaluated. Numerical calculations are combined with experimental observations
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This paper discusses the assembly challenges considering the design and manufacturability of a Wafer Level Thin Film Package in MEMS applications. The assembly processes are discussed. The loads associated with these processes are illustrated and evaluated. Numerical calculations are combined with experimental observations in order to estimate the assembly risks. Our results emphasize the need for concurrent design for assembly. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessReview Phototactic and Chemotactic Signal Transduction by Transmembrane Receptors and Transducers in Microorganisms
Sensors 2010, 10(4), 4010-4039; doi:10.3390/s100404010
Received: 28 January 2010 / Revised: 29 March 2010 / Accepted: 9 April 2010 / Published: 20 April 2010
Cited by 15 | PDF Full-text (732 KB) | HTML Full-text | XML Full-text
Abstract
Microorganisms show attractant and repellent responses to survive in the various environments in which they live. Those phototaxic (to light) and chemotaxic (to chemicals) responses are regulated by membrane-embedded receptors and transducers. This article reviews the following: (1) the signal relay mechanisms by
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Microorganisms show attractant and repellent responses to survive in the various environments in which they live. Those phototaxic (to light) and chemotaxic (to chemicals) responses are regulated by membrane-embedded receptors and transducers. This article reviews the following: (1) the signal relay mechanisms by two photoreceptors, Sensory Rhodopsin I (SRI) and Sensory Rhodopsin II (SRII) and their transducers (HtrI and HtrII) responsible for phototaxis in microorganisms; and (2) the signal relay mechanism of a chemoreceptor/transducer protein, Tar, responsible for chemotaxis in E. coli. Based on results mainly obtained by our group together with other findings, the possible molecular mechanisms for phototaxis and chemotaxis are discussed. Full article
(This article belongs to the Special Issue Advances in Transducers)
Open AccessReview One-Dimensional Oxide Nanostructures as Gas-Sensing Materials: Review and Issues
Sensors 2010, 10(4), 4083-4099; doi:10.3390/s100404083
Received: 3 March 2010 / Revised: 15 April 2010 / Accepted: 16 April 2010 / Published: 22 April 2010
Cited by 142 | PDF Full-text (4543 KB) | HTML Full-text | XML Full-text
Abstract
In this article, we review gas sensor application of one-dimensional (1D) metal-oxide nanostructures with major emphases on the types of device structure and issues for realizing practical sensors. One of the most important steps in fabricating 1D-nanostructure devices is manipulation and making electrical
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In this article, we review gas sensor application of one-dimensional (1D) metal-oxide nanostructures with major emphases on the types of device structure and issues for realizing practical sensors. One of the most important steps in fabricating 1D-nanostructure devices is manipulation and making electrical contacts of the nanostructures. Gas sensors based on individual 1D nanostructure, which were usually fabricated using electron-beam lithography, have been a platform technology for fundamental research. Recently, gas sensors with practical applicability were proposed, which were fabricated with an array of 1D nanostructures using scalable micro-fabrication tools. In the second part of the paper, some critical issues are pointed out including long-term stability, gas selectivity, and room-temperature operation of 1D-nanostructure-based metal-oxide gas sensors. Full article
(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)

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