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Sensors, Volume 10, Issue 12 (December 2010) , Pages 10506-11661

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Open AccessArticle Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring
Sensors 2010, 10(12), 11644-11661; https://doi.org/10.3390/s101211644
Received: 21 October 2010 / Revised: 8 December 2010 / Accepted: 14 December 2010 / Published: 21 December 2010
Cited by 41 | Viewed by 5658 | PDF Full-text (2328 KB) | HTML Full-text | XML Full-text
Abstract
The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage
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The electromechanical (EM) impedance technique using piezoelectric lead zirconate titanate (PZT) transducers for structural health monitoring (SHM) has attracted considerable attention in various engineering fields. In the conventional EM impedance technique, the EM admittance of a PZT transducer is used as a damage indicator. Statistical analysis methods such as root mean square deviation (RMSD) have been employed to associate the damage level with the changes in the EM admittance signatures, but it is difficult to determine the location of damage using such methods. This paper proposes a new approach by dividing the large frequency (30–400 kHz) range into sub-frequency intervals and calculating their respective RMSD values. The RMSD of the sub-frequency intervals (RMSD-S) will be used to study the severity and location of damage. An experiment is carried out on a real size concrete structure subjected to artificial damage. It is observed that damage close to the PZT changes the high frequency range RMSD-S significantly, while the damage far away from the PZT changes the RMSD-S in the low frequency range significantly. The relationship between the frequency range and the PZT sensing region is also presented. Finally, a damage identification scheme is proposed to estimate the location and severity of damage in concrete structures. Full article
(This article belongs to the Special Issue Advanced Sensing Technology for Nondestructive Evaluation)
Open AccessArticle Detection of Cartilage Oligomeric Matrix Protein Using a Quartz Crystal Microbalance
Sensors 2010, 10(12), 11633-11643; https://doi.org/10.3390/s101211633
Received: 26 October 2010 / Revised: 10 December 2010 / Accepted: 11 December 2010 / Published: 20 December 2010
Cited by 5 | Viewed by 5817 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
Current methods for diagnosing early stage osteoarthritis (OA) based on the magnetic resonance imaging and enzyme-linked immunosorbent assay methods are specific, but require specialized laboratory facilities and highly trained personal to obtain a definitive result. In this work, a user friendly and non-invasive
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Current methods for diagnosing early stage osteoarthritis (OA) based on the magnetic resonance imaging and enzyme-linked immunosorbent assay methods are specific, but require specialized laboratory facilities and highly trained personal to obtain a definitive result. In this work, a user friendly and non-invasive quartz crystal microbalance (QCM) immunosensor method has been developed to detect Cartilage Oligomeric Matrix Protein (COMP) for early stage OA diagnosis. This QCM immunosensor was fabricated to immobilize COMP antibodies utilizing the self-assembled monolayer technique. The surface properties of the immunosensor were characterized by its FTIR and electrochemical impedance spectra (EIS). The feasibility study was based on urine samples obtained from 41 volunteers. Experiments were carried out in a flow system and the reproducibility of the electrodes was evaluated by the impedance measured by EIS. Its potential dynamically monitored the immunoreaction processes and could increase the efficiency and sensitivity of COMP detection in laboratory-cultured preparations and clinical samples. The frequency responses of the QCM immunosensor changed from 6 kHz when testing 50 ng/mL COMP concentration. The linear regression equation of frequency shift and COMP concentration was determined as: y = 0.0872 x + 1.2138 (R2 = 0.9957). The COMP in urine was also determined by both QCM and EIS for comparison. A highly sensitive, user friendly and cost effective analytical method for the early stage OA diagnosis has thus been successfully developed. Full article
(This article belongs to the Special Issue Immunosensors)
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Open AccessArticle Performance Bound for Extended Target Tracking Using High Resolution Sensors
Sensors 2010, 10(12), 11618-11632; https://doi.org/10.3390/s101211618
Received: 3 December 2010 / Revised: 15 December 2010 / Accepted: 16 December 2010 / Published: 20 December 2010
Cited by 4 | Viewed by 5075 | PDF Full-text (313 KB) | HTML Full-text | XML Full-text
Abstract
This article concerns the problem of the estimation bound for tracking an extended target observed by a high resolution sensor. Two types of commonly used models for extended targets and the corresponding posterior Cramer-Rao lower bound (PCRLB) are discussed. The first type is
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This article concerns the problem of the estimation bound for tracking an extended target observed by a high resolution sensor. Two types of commonly used models for extended targets and the corresponding posterior Cramer-Rao lower bound (PCRLB) are discussed. The first type is the equation-extension model which extends the state space to include parameters such as target size and shape. Thus, the extended state vector can be estimated through the measurements obtained by a high resolution sensor. The measurement vector is also an expansion of the conventional one, and the additional measurements such as target extent can provide extra information for the estimation. The second model is based on multiple target measurements, each of which is an independent random draw from a spatial probability distribution. As the number of measurements per frame is unknown and random, the general form of the measurement contribution to the Fisher information matrix (FIM) conditional on the number of measurements is presented, and an extended information reduction factor (EIRF) approach is proposed to calculate the overall FIM and, therefore, the PCRLB. The bound of the second extended target model is also less than that of the point model, on condition that the average number of measurements is greater than one. Illustrative simulation examples of the two models are discussed and demonstrated. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell
Sensors 2010, 10(12), 11605-11617; https://doi.org/10.3390/s101211605
Received: 12 November 2010 / Revised: 9 December 2010 / Accepted: 14 December 2010 / Published: 20 December 2010
Cited by 4 | Viewed by 5182 | PDF Full-text (666 KB) | HTML Full-text | XML Full-text
Abstract
Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical
[...] Read more.
Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 μm-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Large Scale Application of Vibration Sensors for Fan Monitoring at Commercial Layer Hen Houses
Sensors 2010, 10(12), 11590-11604; https://doi.org/10.3390/s101211590
Received: 21 September 2010 / Revised: 16 November 2010 / Accepted: 26 November 2010 / Published: 16 December 2010
Cited by 6 | Viewed by 6237 | PDF Full-text (409 KB) | HTML Full-text | XML Full-text
Abstract
Continuously monitoring the operation of each individual fan can significantly improve the measurement quality of aerial pollutant emissions from animal buildings that have a large number of fans. To monitor the fan operation by detecting the fan vibration is a relatively new technique.
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Continuously monitoring the operation of each individual fan can significantly improve the measurement quality of aerial pollutant emissions from animal buildings that have a large number of fans. To monitor the fan operation by detecting the fan vibration is a relatively new technique. A low-cost electronic vibration sensor was developed and commercialized. However, its large scale application has not yet been evaluated. This paper presents long-term performance results of this vibration sensor at two large commercial layer houses. Vibration sensors were installed on 164 fans of 130 cm diameter to continuously monitor the fan on/off status for two years. The performance of the vibration sensors was compared with fan rotational speed (FRS) sensors. The vibration sensors exhibited quick response and high sensitivity to fan operations and therefore satisfied the general requirements of air quality research. The study proved that detecting fan vibration was an effective method to monitor the on/off status of a large number of single-speed fans. The vibration sensor itself was $2 more expensive than a magnetic proximity FRS sensor but the overall cost including installation and data acquisition hardware was $77 less expensive than the FRS sensor. A total of nine vibration sensors failed during the study and the failure rate was related to the batches of product. A few sensors also exhibited unsteady sensitivity. As a new product, the quality of the sensor should be improved to make it more reliable and acceptable. Full article
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Open AccessArticle A Wireless Sensor Network-Based Ubiquitous Paprika Growth Management System
Sensors 2010, 10(12), 11566-11589; https://doi.org/10.3390/s101211566
Received: 20 November 2010 / Revised: 9 December 2010 / Accepted: 14 December 2010 / Published: 16 December 2010
Cited by 20 | Viewed by 4952 | PDF Full-text (1311 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Network (WSN) technology can facilitate advances in productivity, safety and human quality of life through its applications in various industries. In particular, the application of WSN technology to the agricultural area, which is labor-intensive compared to other industries, and in addition
[...] Read more.
Wireless Sensor Network (WSN) technology can facilitate advances in productivity, safety and human quality of life through its applications in various industries. In particular, the application of WSN technology to the agricultural area, which is labor-intensive compared to other industries, and in addition is typically lacking in IT technology applications, adds value and can increase the agricultural productivity. This study attempts to establish a ubiquitous agricultural environment and improve the productivity of farms that grow paprika by suggesting a ‘Ubiquitous Paprika Greenhouse Management System’ using WSN technology. The proposed system can collect and monitor information related to the growth environment of crops outside and inside paprika greenhouses by installing WSN sensors and monitoring images captured by CCTV cameras. In addition, the system provides a paprika greenhouse environment control facility for manual and automatic control from a distance, improves the convenience and productivity of users, and facilitates an optimized environment to grow paprika based on the growth environment data acquired by operating the system. Full article
Open AccessReview The Use of Wearable Inertial Motion Sensors in Human Lower Limb Biomechanics Studies: A Systematic Review
Sensors 2010, 10(12), 11556-11565; https://doi.org/10.3390/s101211556
Received: 1 November 2010 / Revised: 1 December 2010 / Accepted: 14 December 2010 / Published: 16 December 2010
Cited by 89 | Viewed by 9135 | PDF Full-text (218 KB) | HTML Full-text | XML Full-text
Abstract
Wearable motion sensors consisting of accelerometers, gyroscopes and magnetic sensors are readily available nowadays. The small size and low production costs of motion sensors make them a very good tool for human motions analysis. However, data processing and accuracy of the collected data
[...] Read more.
Wearable motion sensors consisting of accelerometers, gyroscopes and magnetic sensors are readily available nowadays. The small size and low production costs of motion sensors make them a very good tool for human motions analysis. However, data processing and accuracy of the collected data are important issues for research purposes. In this paper, we aim to review the literature related to usage of inertial sensors in human lower limb biomechanics studies. A systematic search was done in the following search engines: ISI Web of Knowledge, Medline, SportDiscus and IEEE Xplore. Thirty nine full papers and conference abstracts with related topics were included in this review. The type of sensor involved, data collection methods, study design, validation methods and its applications were reviewed. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessReview Nitrite Biosensing via Selective Enzymes—A Long but Promising Route
Sensors 2010, 10(12), 11530-11555; https://doi.org/10.3390/s101211530
Received: 9 October 2010 / Revised: 19 November 2010 / Accepted: 6 December 2010 / Published: 15 December 2010
Cited by 24 | Viewed by 8299 | PDF Full-text (792 KB) | HTML Full-text | XML Full-text
Abstract
The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has
[...] Read more.
The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has recently implemented a number of rules to restrict its level in drinking waters and food products. Although several analytical protocols have been proposed for nitrite quantification, none of them enable a reliable and quick analysis of complex samples. An alternative approach relies on the construction of biosensing devices using stable enzymes, with both high activity and specificity for nitrite. In this paper we review the current state-of-the-art in the field of electrochemical and optical biosensors using nitrite reducing enzymes as biorecognition elements and discuss the opportunities and challenges in this emerging market. Full article
(This article belongs to the Special Issue Bio-devices and Materials)
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Open AccessArticle Characterization of Buoyant Fluorescent Particles for Field Observations of Water Flows
Sensors 2010, 10(12), 11512-11529; https://doi.org/10.3390/s101211512
Received: 9 October 2010 / Revised: 10 November 2010 / Accepted: 11 November 2010 / Published: 15 December 2010
Cited by 20 | Viewed by 8208 | PDF Full-text (2394 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres’ fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural
[...] Read more.
In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres’ fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural drainage networks. Experiments are conducted in a broad range of clay concentrations and particle immersion depths by using photoconductive cells and image-based sensing technologies. Results obtained with both methodologies exhibit comparable trends and show that the considered particles are fairly detectable in critically turbid water flows. Further information on performance and integration of the studied microspheres in low-cost measurement instrumentation for field observations is obtained through experiments conducted in a custom built miniature water channel. This experimental characterization provides a first assessment of the feasibility of commercially available buoyant fluorescent beads in the analysis of high turbidity surface water flows. The proposed technology may serve as a minimally invasive sensing system for hazardous events, such as pollutant diffusion in natural streams and flash flooding due to extreme rainfall. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
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Open AccessArticle A Combined Experimental and Theoretical Study on the Immunoassay of Human Immunoglobulin Using a Quartz Crystal Microbalance
Sensors 2010, 10(12), 11498-11511; https://doi.org/10.3390/s101211498
Received: 3 November 2010 / Revised: 29 November 2010 / Accepted: 6 December 2010 / Published: 15 December 2010
Cited by 5 | Viewed by 6117 | PDF Full-text (1201 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We investigate a immunoassay biosensor that employs a Quartz Crystal Microbalance (QCM) to detect the specific binding reaction of the (Human IgG1)-(Anti-Human IgG1) protein pair under physiological conditions. In addition to experiments, a three dimensional time domain finite element method (FEM) was used
[...] Read more.
We investigate a immunoassay biosensor that employs a Quartz Crystal Microbalance (QCM) to detect the specific binding reaction of the (Human IgG1)-(Anti-Human IgG1) protein pair under physiological conditions. In addition to experiments, a three dimensional time domain finite element method (FEM) was used to perform simulations for the biomolecular binding reaction in microfluidic channels. In particular, we discuss the unsteady convective diffusion in the transportation tube, which conveys the buffer solution containing the analyte molecules into the micro-channel where the QCM sensor lies. It is found that the distribution of the analyte concentration in the tube is strongly affected by the flow field, yielding large discrepancies between the simulations and experimental results. Our analysis shows that the conventional assumption of the analyte concentration in the inlet of the micro-channel being uniform and constant in time is inadequate. In addition, we also show that the commonly used procedure in kinetic analysis for estimating binding rate constants from the experimental data would underestimate these rate constants due to neglected diffusion processes from the inlet to the reaction surface. A calibration procedure is proposed to supplement the basic kinetic analysis, thus yielding better consistency with experiments. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle Map Building and Monte Carlo Localization Using Global Appearance of Omnidirectional Images
Sensors 2010, 10(12), 11468-11497; https://doi.org/10.3390/s101211468
Received: 30 September 2010 / Revised: 25 November 2010 / Accepted: 28 November 2010 / Published: 14 December 2010
Cited by 27 | Viewed by 7396 | PDF Full-text (11125 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we deal with the problem of map building and localization of a mobile robot in an environment using the information provided by an omnidirectional vision sensor that is mounted on the robot. Our main objective consists of studying the feasibility
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In this paper we deal with the problem of map building and localization of a mobile robot in an environment using the information provided by an omnidirectional vision sensor that is mounted on the robot. Our main objective consists of studying the feasibility of the techniques based in the global appearance of a set of omnidirectional images captured by this vision sensor to solve this problem. First, we study how to describe globally the visual information so that it represents correctly locations and the geometrical relationships between these locations. Then, we integrate this information using an approach based on a spring-mass-damper model, to create a topological map of the environment. Once the map is built, we propose the use of a Monte Carlo localization approach to estimate the most probable pose of the vision system and its trajectory within the map. We perform a comparison in terms of computational cost and error in localization. The experimental results we present have been obtained with real indoor omnidirectional images. Full article
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Open AccessArticle Pervasive Monitoring—An Intelligent Sensor Pod Approach for Standardised Measurement Infrastructures
Sensors 2010, 10(12), 11440-11467; https://doi.org/10.3390/s101211440
Received: 8 October 2010 / Revised: 19 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
Cited by 14 | Viewed by 5714 | PDF Full-text (1229 KB) | HTML Full-text | XML Full-text
Abstract
Geo-sensor networks have traditionally been built up in closed monolithic systems, thus limiting trans-domain usage of real-time measurements. This paper presents the technical infrastructure of a standardised embedded sensing device, which has been developed in the course of the Live Geography approach. The
[...] Read more.
Geo-sensor networks have traditionally been built up in closed monolithic systems, thus limiting trans-domain usage of real-time measurements. This paper presents the technical infrastructure of a standardised embedded sensing device, which has been developed in the course of the Live Geography approach. The sensor pod implements data provision standards of the Sensor Web Enablement initiative, including an event-based alerting mechanism and location-aware Complex Event Processing functionality for detection of threshold transgression and quality assurance. The goal of this research is that the resultant highly flexible sensing architecture will bring sensor network applications one step further towards the realisation of the vision of a “digital skin for planet earth”. The developed infrastructure can potentially have far-reaching impacts on sensor-based monitoring systems through the deployment of ubiquitous and fine-grained sensor networks. This in turn allows for the straight-forward use of live sensor data in existing spatial decision support systems to enable better-informed decision-making. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Myocardial Motion Analysis for Determination of Tei-Index of Human Heart
Sensors 2010, 10(12), 11428-11439; https://doi.org/10.3390/s101211428
Received: 4 November 2010 / Revised: 24 November 2010 / Accepted: 8 December 2010 / Published: 13 December 2010
Cited by 14 | Viewed by 4739 | PDF Full-text (675 KB) | HTML Full-text | XML Full-text
Abstract
The Tei index, an important indicator of heart function, lacks a direct method to compute because it is difficult to directly evaluate the isovolumic contraction time (ICT) and isovolumic relaxation time (IRT) from which the Tei index can be obtained. In this paper,
[...] Read more.
The Tei index, an important indicator of heart function, lacks a direct method to compute because it is difficult to directly evaluate the isovolumic contraction time (ICT) and isovolumic relaxation time (IRT) from which the Tei index can be obtained. In this paper, based on the proposed method of accurately measuring the cardiac cycle physical phase, a direct method of calculating the Tei index is presented. The experiments based on real heart medical images show the effectiveness of this method. Moreover, a new method of calculating left ventricular wall motion amplitude is proposed and the experiments show its satisfactory performance. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
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Open AccessArticle Direct Detection of the Biological Toxin in Acidic Environment by Electrochemical Impedimetric Immunosensor
Sensors 2010, 10(12), 11414-11427; https://doi.org/10.3390/s101211414
Received: 29 September 2010 / Revised: 27 October 2010 / Accepted: 22 November 2010 / Published: 13 December 2010
Cited by 11 | Viewed by 4628 | PDF Full-text (1031 KB) | HTML Full-text | XML Full-text
Abstract
This study describes the direct detection of the biological toxin (Ricin) in acidic environment without pH adjustment by hydrophobically modified electrochemical impedance immunosensor (EII). The nano-porous aluminum substrate for EII was hydrophobically modified via self-assembled monolayer (SAM) of APTES. Biosensor for the detection
[...] Read more.
This study describes the direct detection of the biological toxin (Ricin) in acidic environment without pH adjustment by hydrophobically modified electrochemical impedance immunosensor (EII). The nano-porous aluminum substrate for EII was hydrophobically modified via self-assembled monolayer (SAM) of APTES. Biosensor for the detection of the Ricin was fabricated by the covalent cross-linking of antibody (Ab) with APTES-SAM. The immunoreactions between the immobilized Ab and the biological toxin in several diagnostic solutions were monitored by the electrochemical impedance spectroscopy (EIS) under the polarization of EII versus reference electrode. EII could detect the presence of the biological toxin in acidic foods in 20 mins without pH adjustment. The negatively charged ions including hydroxides would be adsorbed on the hydrophobic body of APTES-SAMs by the polarization during EIS analysis, and offset the effect of acids on the immunological activity of the immobilized Ab. It suggested that the adsorption of negatively charged ions helped to keep the immunological activities of the immobilized Ab on EII in acidic environment. Proposed mechanism of the localized pH adjustment that makes possible immunoreaction occurrence in low pH sample matrix is briefly discussed. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle An Efficient Management System for Wireless Sensor Networks
Sensors 2010, 10(12), 11400-11413; https://doi.org/10.3390/s101211400
Received: 21 October 2010 / Revised: 16 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
Cited by 13 | Viewed by 6743 | PDF Full-text (903 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks have garnered considerable attention recently. Networks typically have many sensor nodes, and are used in commercial, medical, scientific, and military applications for sensing and monitoring the physical world. Many researchers have attempted to improve wireless sensor network management efficiency. A
[...] Read more.
Wireless sensor networks have garnered considerable attention recently. Networks typically have many sensor nodes, and are used in commercial, medical, scientific, and military applications for sensing and monitoring the physical world. Many researchers have attempted to improve wireless sensor network management efficiency. A Simple Network Management Protocol (SNMP)-based sensor network management system was developed that is a convenient and effective way for managers to monitor and control sensor network operations. This paper proposes a novel WSNManagement system that can show the connections stated of relationships among sensor nodes and can be used for monitoring, collecting, and analyzing information obtained by wireless sensor networks. The proposed network management system uses collected information for system configuration. The function of performance analysis facilitates convenient management of sensors. Experimental results show that the proposed method enhances the alive rate of an overall sensor node system, reduces the packet lost rate by roughly 5%, and reduces delay time by roughly 0.2 seconds. Performance analysis demonstrates that the proposed system is effective for wireless sensor network management. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Resolution Enhancement in Surface Plasmon Resonance Sensor Based on Waveguide Coupled Mode by Combining a Bimetallic Approach
Sensors 2010, 10(12), 11390-11399; https://doi.org/10.3390/s101211390
Received: 20 August 2010 / Revised: 23 November 2010 / Accepted: 7 December 2010 / Published: 13 December 2010
Cited by 70 | Viewed by 5180 | PDF Full-text (323 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we present and demonstrate a new route to a great enhancement in resolution of surface plasmon resonance sensors. Basically, our approach combines a waveguide coupled plasmonic mode and a kind of Au/Ag bimetallic enhancement concept. Theoretical modeling was carried out
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In this study, we present and demonstrate a new route to a great enhancement in resolution of surface plasmon resonance sensors. Basically, our approach combines a waveguide coupled plasmonic mode and a kind of Au/Ag bimetallic enhancement concept. Theoretical modeling was carried out by solving Fresnel equations for the multilayer stack of prism/Ag inner-metal layer/dielectric waveguide/Au outer-metal layer. The inner Ag layer couples incident light to a guided wave and makes more fields effectively concentrated on the outer Au surface. A substantial enhancement in resolution was experimentally verified for the model stack using a ZnS-SiO2 waveguide layer. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Reliable Location-Based Services from Radio Navigation Systems
Sensors 2010, 10(12), 11369-11389; https://doi.org/10.3390/s101211369
Received: 25 October 2010 / Revised: 16 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
Cited by 3 | Viewed by 5514 | PDF Full-text (605 KB) | HTML Full-text | XML Full-text
Abstract
Loran is a radio-based navigation system originally designed for naval applications. We show that Loran-C’s high-power and high repeatable accuracy are fantastic for security applications. First, we show how to derive a precise location tag—with a sensitivity of about 20 meters—that is difficult
[...] Read more.
Loran is a radio-based navigation system originally designed for naval applications. We show that Loran-C’s high-power and high repeatable accuracy are fantastic for security applications. First, we show how to derive a precise location tag—with a sensitivity of about 20 meters—that is difficult to project to an exact location. A device can use our location tag to block or allow certain actions, without knowing its precise location. To ensure that our tag is reproducible we make use of fuzzy extractors, a mechanism originally designed for biometric authentication. We build a fuzzy extractor specifically designed for radio-type errors and give experimental evidence to show its effectiveness. Second, we show that our location tag is difficult to predict from a distance. For example, an observer cannot predict the location tag inside a guarded data center from a few hundreds of meters away. As an application, consider a location-aware disk drive that will only work inside the data center. An attacker who steals the device and is capable of spoofing Loran-C signals, still cannot make the device work since he does not know what location tag to spoof. We provide experimental data supporting our unpredictability claim. Full article
(This article belongs to the Section Physical Sensors)
Open AccessReview Sensing-Applications of Surface-Based Single Vesicle Arrays
Sensors 2010, 10(12), 11352-11368; https://doi.org/10.3390/s101211352
Received: 23 October 2010 / Revised: 30 November 2010 / Accepted: 7 December 2010 / Published: 13 December 2010
Cited by 37 | Viewed by 8184 | PDF Full-text (1718 KB) | HTML Full-text | XML Full-text
Abstract
A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic “scaffold” (Ø ≥ 13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or
[...] Read more.
A single lipid vesicle can be regarded as an autonomous ultra-miniaturised 3D biomimetic “scaffold” (Ø ≥ 13 nm) ideally suited for reconstitution and interrogation of biochemical processes. The enclosing lipid bilayer membrane of a vesicle can be applied for studying binding (protein/lipid or receptor/ligand interactions) or transmembrane events (membrane permeability or ion channel activation) while the aqueous vesicle lumen can be used for confining few or single macromolecules and probe, e.g., protein folding, catalytic pathways of enzymes or more complex biochemical reactions, such as signal transduction cascades. Immobilisation (arraying) of single vesicles on a solid support is an extremely useful technique that allows detailed characterisation of vesicle preparations using surface sensitive techniques, in particular fluorescence microscopy. Surface-based single vesicle arrays allow a plethora of prototypic sensing applications in a high throughput format with high spatial and high temporal resolution. In this review we present a series of applications of single vesicle arrays for screening/sensing of: membrane curvature dependent protein-lipid interactions, bilayer tension, reactions triggered in the vesicle lumen, the activity of transmembrane protein channels and biological membrane fusion reactions. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
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Open AccessArticle Determination of Silver(I) by Differential Pulse Voltammetry Using a Glassy Carbon Electrode Modified with Synthesized N-(2-Aminoethyl)-4,4'-Bipyridine
Sensors 2010, 10(12), 11340-11351; https://doi.org/10.3390/s101211340
Received: 12 November 2010 / Revised: 1 December 2010 / Accepted: 2 December 2010 / Published: 13 December 2010
Cited by 19 | Viewed by 5612 | PDF Full-text (297 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A new modified glassy carbon electrode (GCE) based on a synthesized N-(2-aminoethyl)-4,4'-bipyridine (ABP) was developed for the determination of Ag(I) by differential pulse voltammetry (DPV). ABP was covalently immobilized on GC electrodes surface using 4-nitrobenzendiazonium (4-NBD) and glutaraldehyde (GA). The Ag(I) ions
[...] Read more.
A new modified glassy carbon electrode (GCE) based on a synthesized N-(2-aminoethyl)-4,4'-bipyridine (ABP) was developed for the determination of Ag(I) by differential pulse voltammetry (DPV). ABP was covalently immobilized on GC electrodes surface using 4-nitrobenzendiazonium (4-NBD) and glutaraldehyde (GA). The Ag(I) ions were preconcentrated by chemical interaction with bipyridine under a negative potential (−0.6 V); then the reduced ions were oxidized by differential pulse voltammetry and a peak was observed at 0.34 V. The calibration curve was linear in the concentration range from 0.05 μM to 1 μM Ag(I) with a detection limit of 0.025 μM and RSD = 3.6%, for 0.4 μM Ag(I). The presence of several common ions in more than 125-fold excess had no effect on the determination of Ag(I). The developed sensor was applied to the determination of Ag(I) in water samples using a standard addition method. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Bioinspired Electronic White Cane Implementation Based on a LIDAR, a Tri-Axial Accelerometer and a Tactile Belt
Sensors 2010, 10(12), 11322-11339; https://doi.org/10.3390/s101211322
Received: 23 October 2010 / Revised: 25 November 2010 / Accepted: 3 December 2010 / Published: 10 December 2010
Cited by 21 | Viewed by 5296 | PDF Full-text (379 KB) | HTML Full-text | XML Full-text
Abstract
This work proposes the creation of a bioinspired electronic white cane for blind people using the whiskers principle for short-range navigation and exploration. Whiskers are coarse hairs of an animal's face that tells the animal that it has touched something using the nerves
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This work proposes the creation of a bioinspired electronic white cane for blind people using the whiskers principle for short-range navigation and exploration. Whiskers are coarse hairs of an animal's face that tells the animal that it has touched something using the nerves of the skin. In this work the raw data acquired from a low-size terrestrial LIDAR and a tri-axial accelerometer is converted into tactile information using several electromagnetic devices configured as a tactile belt. The LIDAR and the accelerometer are attached to the user’s forearm and connected with a wire to the control unit placed on the belt. Early validation experiments carried out in the laboratory are promising in terms of usability and description of the environment. Full article
(This article belongs to the Special Issue Bioinspired Sensor Systems)
Open AccessArticle A Ferrocene-Quinoxaline Derivative as a Highly Selective Probe for Colorimetric and Redox Sensing of Toxic Mercury(II) Cations
Sensors 2010, 10(12), 11311-11321; https://doi.org/10.3390/s101211311
Received: 20 October 2010 / Revised: 15 November 2010 / Accepted: 26 November 2010 / Published: 10 December 2010
Cited by 27 | Viewed by 5701 | PDF Full-text (331 KB) | HTML Full-text | XML Full-text
Abstract
A new chemosensor molecule 3 based on a ferrocene-quinoxaline dyad recognizes mercury (II) cations in acetonitrile solution. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red-shift (Δλ = 140 nm) of the low-energy band, are observed in its
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A new chemosensor molecule 3 based on a ferrocene-quinoxaline dyad recognizes mercury (II) cations in acetonitrile solution. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red-shift (Δλ = 140 nm) of the low-energy band, are observed in its absorption spectrum. This change in the absorption spectrum is accompanied by a colour change from orange to deep green, which can be used for a “naked-eye” detection of this metal cation. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride
Sensors 2010, 10(12), 11301-11310; https://doi.org/10.3390/s101211301
Received: 8 November 2010 / Revised: 6 December 2010 / Accepted: 9 December 2010 / Published: 10 December 2010
Cited by 22 | Viewed by 5477 | PDF Full-text (413 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents a novel pressure sensor based on a silicon nitride (SiNx) nanocoated long-period grating (LPG). The high-temperature, radio-frequency plasma-enhanced chemical-vapor-deposited (RF PECVD) SiNx nanocoating was applied to tune the sensitivity of the LPG to the external refractive index.
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The paper presents a novel pressure sensor based on a silicon nitride (SiNx) nanocoated long-period grating (LPG). The high-temperature, radio-frequency plasma-enhanced chemical-vapor-deposited (RF PECVD) SiNx nanocoating was applied to tune the sensitivity of the LPG to the external refractive index. The technique allows for deposition of good quality, hard and wear-resistant nanofilms as required for optical sensors. Thanks to the SiNx nanocoating it is possible to overcome a limitation of working in the external-refractive-index range, which for a bare fiber cannot be close to that of the cladding. The nanocoated LPG-based sensing structure we developed is functional in high-refractive-index liquids (nD > 1.46) such as oil or gasoline, with pressure sensitivity as high as when water is used as a working liquid. The nanocoating developed for this experiment not only has the highest refractive index ever achieved in LPGs (n > 2.2 at λ = 1,550 nm), but is also the thinnest ( Full article
(This article belongs to the Section Physical Sensors)
Open AccessReview Ca2+-Regulated Photoproteins: Effective Immunoassay Reporters
Sensors 2010, 10(12), 11287-11300; https://doi.org/10.3390/s101211287
Received: 29 October 2010 / Revised: 24 November 2010 / Accepted: 3 December 2010 / Published: 10 December 2010
Cited by 19 | Viewed by 4590 | PDF Full-text (326 KB) | HTML Full-text | XML Full-text
Abstract
Ca2+-regulated photoproteins of luminous marine coelenterates are of interest and a challenge for researchers as a unique bioluminescent system and as a promising analytical instrument for both in vivo and in vitro applications. The proteins are comprehensively studied as to biochemical
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Ca2+-regulated photoproteins of luminous marine coelenterates are of interest and a challenge for researchers as a unique bioluminescent system and as a promising analytical instrument for both in vivo and in vitro applications. The proteins are comprehensively studied as to biochemical properties, tertiary structures, bioluminescence mechanism, etc. This knowledge, along with available recombinant proteins serves the basis for development of unique bioluminescent detection systems that are “self-contained”, triggerable, fast, highly sensitive, and non-hazardous. In the paper, we focus on the use of photoproteins as reporters in binding assays based on immunological recognition element—bioluminescent immunoassay and hybridization immunoassay, their advantages and prospects. Full article
(This article belongs to the Special Issue Immunosensors)
Open AccessArticle A High-Throughput Enzyme Assay for Organophosphate Residues in Milk
Sensors 2010, 10(12), 11274-11286; https://doi.org/10.3390/s101211274
Received: 17 September 2010 / Revised: 15 November 2010 / Accepted: 7 December 2010 / Published: 9 December 2010
Cited by 9 | Viewed by 4277 | PDF Full-text (306 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A rapid, high-sensitivity, chemiluminescence (CL) enzyme assay for the determination of organophosphate (OP) residues in milk is presented. The assay for quantification of OP residues in milk is based on the inhibition of enzyme butyrylcholinesterase (BuChE). BuChE was stabilized and preloaded in 384
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A rapid, high-sensitivity, chemiluminescence (CL) enzyme assay for the determination of organophosphate (OP) residues in milk is presented. The assay for quantification of OP residues in milk is based on the inhibition of enzyme butyrylcholinesterase (BuChE). BuChE was stabilized and preloaded in 384 well plates at 30 °C. The assay permits rapid determination of OPs in milk within 12 min including an incubation step. The enzyme assay was tested for individual and mixtures of OPs such as methyl paraoxon (MPOx), methyl parathion (MP) and malathion (MT) in milk to evaluate their synergistic effect on BuChE inhibition. Good linearity was obtained in the range 0.005–50 µg·L−1 for MPOx and 0.5–1,000 µg·L−1 for MP as well as MT in milk. Mean recovery of 93.2%–98.6% was obtained for MPOx spiked milk samples with 0.99%–1.67% reproducibility (RSD). The proposed method facilitated rapid screening of milk samples in 384 well plate formats with further miniaturization presented in 1,536 well plates. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Approximate Nearest Neighbor Search by Residual Vector Quantization
Sensors 2010, 10(12), 11259-11273; https://doi.org/10.3390/s101211259
Received: 9 October 2010 / Revised: 20 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 42 | Viewed by 6182 | PDF Full-text (172 KB) | HTML Full-text | XML Full-text
Abstract
A recently proposed product quantization method is efficient for large scale approximate nearest neighbor search, however, its performance on unstructured vectors is limited. This paper introduces residual vector quantization based approaches that are appropriate for unstructured vectors. Database vectors are quantized by residual
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A recently proposed product quantization method is efficient for large scale approximate nearest neighbor search, however, its performance on unstructured vectors is limited. This paper introduces residual vector quantization based approaches that are appropriate for unstructured vectors. Database vectors are quantized by residual vector quantizer. The reproductions are represented by short codes composed of their quantization indices. Euclidean distance between query vector and database vector is approximated by asymmetric distance, i.e., the distance between the query vector and the reproduction of the database vector. An efficient exhaustive search approach is proposed by fast computing the asymmetric distance. A straight forward non-exhaustive search approach is proposed for large scale search. Our approaches are compared to two state-of-the-art methods, spectral hashing and product quantization, on both structured and unstructured datasets. Results show that our approaches obtain the best results in terms of the trade-off between search quality and memory usage. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Ultrasonic Sensitivity of Strain-Insensitive Fiber Bragg Grating Sensors and Evaluation of Ultrasound-Induced Strain
Sensors 2010, 10(12), 11248-11258; https://doi.org/10.3390/s101211248
Received: 19 October 2010 / Revised: 22 November 2010 / Accepted: 26 November 2010 / Published: 8 December 2010
Cited by 36 | Viewed by 5514 | PDF Full-text (256 KB) | HTML Full-text | XML Full-text
Abstract
In conventional ultrasound detection in structures, a fiber Bragg grating (FBG) is glued on or embedded in the structure. However, application of strain to the structure can influence the sensitivity of the FBG toward ultrasound and can prevent its effective detection. An FBG
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In conventional ultrasound detection in structures, a fiber Bragg grating (FBG) is glued on or embedded in the structure. However, application of strain to the structure can influence the sensitivity of the FBG toward ultrasound and can prevent its effective detection. An FBG can work as a strain-insensitive ultrasound sensor when it is not directly glued to the monitored structure, but is instead applied to a small thin plate to form a mobile sensor. Another possible configuration is to affix an FBG-inscribed optical fiber without the grating section attached to the monitored structure. In the present study, sensitivity to ultrasound propagated through an aluminum plate was compared for a strain-insensitive FBG sensor and an FBG sensor installed in a conventional manner. Strains induced by ultrasound from a piezoelectric transducer and by quasi-acoustic emission of a pencil lead break were also quantitatively evaluated from the response amplitude of the FBG sensor. Experimental results showed that the reduction in the signal-to-noise ratio for ultrasound detection with strain-insensitive FBG sensors, relative to traditionally-installed FBG sensors, was only 6 dB, and the ultrasound-induced strain varied within a range of sub-micron strains. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Sensor Architecture and Task Classification for Agricultural Vehicles and Environments
Sensors 2010, 10(12), 11226-11247; https://doi.org/10.3390/s101211226
Received: 20 October 2010 / Revised: 26 November 2010 / Accepted: 1 December 2010 / Published: 8 December 2010
Cited by 19 | Viewed by 6892 | PDF Full-text (1176 KB) | HTML Full-text | XML Full-text
Abstract
The long time wish of endowing agricultural vehicles with an increasing degree of autonomy is becoming a reality thanks to two crucial facts: the broad diffusion of global positioning satellite systems and the inexorable progress of computers and electronics. Agricultural vehicles are currently
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The long time wish of endowing agricultural vehicles with an increasing degree of autonomy is becoming a reality thanks to two crucial facts: the broad diffusion of global positioning satellite systems and the inexorable progress of computers and electronics. Agricultural vehicles are currently the only self-propelled ground machines commonly integrating commercial automatic navigation systems. Farm equipment manufacturers and satellite-based navigation system providers, in a joint effort, have pushed this technology to unprecedented heights; yet there are many unresolved issues and an unlimited potential still to uncover. The complexity inherent to intelligent vehicles is rooted in the selection and coordination of the optimum sensors, the computer reasoning techniques to process the acquired data, and the resulting control strategies for automatic actuators. The advantageous design of the network of onboard sensors is necessary for the future deployment of advanced agricultural vehicles. This article analyzes a variety of typical environments and situations encountered in agricultural fields, and proposes a sensor architecture especially adapted to cope with them. The strategy proposed groups sensors into four specific subsystems: global localization, feedback control and vehicle pose, non-visual monitoring, and local perception. The designed architecture responds to vital vehicle tasks classified within three layers devoted to safety, operative information, and automatic actuation. The success of this architecture, implemented and tested in various agricultural vehicles over the last decade, rests on its capacity to integrate redundancy and incorporate new technologies in a practical way. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
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Open AccessArticle Design of a Pressure Sensor Based on Optical Fiber Bragg Grating Lateral Deformation
Sensors 2010, 10(12), 11212-11225; https://doi.org/10.3390/s101211212
Received: 7 September 2010 / Revised: 15 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 30 | Viewed by 5338 | PDF Full-text (595 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes steps involved in the design and realization of a new type of pressure sensor based on the optical fiber Bragg grating. A traditional pressure sensor has very limited usage in heavy industrial environments, particularly in explosive or electromagnetically noisy environments.
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This paper describes steps involved in the design and realization of a new type of pressure sensor based on the optical fiber Bragg grating. A traditional pressure sensor has very limited usage in heavy industrial environments, particularly in explosive or electromagnetically noisy environments. Utilization of optics in these environments eliminates all surrounding influences. An initial motivation for our development was the research, experimental validation, and realization of a complex smart pressure sensor based on the optical principle. The main benefit of this solution consists of increasing sensitivity, resistance to electromagnetic interference, dimensions, and potential increased accuracy. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Study on an Agricultural Environment Monitoring Server System using Wireless Sensor Networks
Sensors 2010, 10(12), 11189-11211; https://doi.org/10.3390/s101211189
Received: 2 November 2010 / Revised: 18 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 82 | Viewed by 5766 | PDF Full-text (1127 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an agricultural environment monitoring server system for monitoring information concerning an outdoors agricultural production environment utilizing Wireless Sensor Network (WSN) technology. The proposed agricultural environment monitoring server system collects environmental and soil information on the outdoors through WSN-based environmental and
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This paper proposes an agricultural environment monitoring server system for monitoring information concerning an outdoors agricultural production environment utilizing Wireless Sensor Network (WSN) technology. The proposed agricultural environment monitoring server system collects environmental and soil information on the outdoors through WSN-based environmental and soil sensors, collects image information through CCTVs, and collects location information using GPS modules. This collected information is converted into a database through the agricultural environment monitoring server consisting of a sensor manager, which manages information collected from the WSN sensors, an image information manager, which manages image information collected from CCTVs, and a GPS manager, which processes location information of the agricultural environment monitoring server system, and provides it to producers. In addition, a solar cell-based power supply is implemented for the server system so that it could be used in agricultural environments with insufficient power infrastructure. This agricultural environment monitoring server system could even monitor the environmental information on the outdoors remotely, and it could be expected that the use of such a system could contribute to increasing crop yields and improving quality in the agricultural field by supporting the decision making of crop producers through analysis of the collected information. Full article
Open AccessArticle An Optical Fiber Viscometer Based on Long-Period Fiber Grating Technology and Capillary Tube Mechanism
Sensors 2010, 10(12), 11174-11188; https://doi.org/10.3390/s101211174
Received: 12 October 2010 / Revised: 18 November 2010 / Accepted: 6 December 2010 / Published: 8 December 2010
Cited by 9 | Viewed by 6996 | PDF Full-text (456 KB) | HTML Full-text | XML Full-text
Abstract
This work addresses the development and assessment of a fiber optical viscometer using a simple and low-cost long-period fiber grating (LPFG) level sensor and a capillary tube mechanism. Previous studies of optical viscosity sensors were conducted by using different optical sensing methods. The
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This work addresses the development and assessment of a fiber optical viscometer using a simple and low-cost long-period fiber grating (LPFG) level sensor and a capillary tube mechanism. Previous studies of optical viscosity sensors were conducted by using different optical sensing methods. The proposed optical viscometer consists of an LPFG sensor, a temperature-controlled chamber, and a cone-shaped reservoir where gravitational force could cause fluid to flow through the capillary tube. We focused on the use of LPFGs as level sensors and the wavelength shifts were not used to quantify the viscosity values of asphalt binders. When the LPFG sensor was immersed in the constant volume (100 mL) AC-20 asphalt binder, a wavelength shift was observed and acquired using LabVIEW software and GPIB controller. The time spent between empty and 100 mL was calculated to determine the discharge time. We simultaneously measured the LPFG-induced discharge time and the transmission spectra both in hot air and AC-20 asphalt binder at five different temperatures, 60, 80, 100, 135, and 170 Celsius. An electromechanical rotational viscometer was also used to measure the viscosities, 0.15–213.80 Pa·s, of the same asphalt binder at the above five temperatures. A non-linear regression analysis was performed to convert LPFG-induced discharge time into viscosities. Comparative analysis shows that the LPFG-induced discharge time agreed well with the viscosities obtained from the rotational viscometer. Full article
(This article belongs to the Section Physical Sensors)
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